JPS61156521A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium giving a stationary image with superior durability and having superior traveling stability and S/N by incorporating fatty acid and glycerol ester into a magnetic layer so as to improve the lubricity of the magnetic layer. CONSTITUTION:This magnetic recording medium has a magnetic layer contg. fatty acid and glycerol ester. The preferred weight ratio of glycerol ester:fatty acid is (1:10)-(3:1), especially (1:5)-(2:1). The magnetic recording medium has the magnetic layer 2 on one side of a support 1. A BC layer 3 may be formed on the other side.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to magnetic recording media such as magnetic tapes, magnetic sheets, and magnetic disks.

BACKGROUND OF THE INVENTION Generally, magnetic recording media such as magnetic tapes are manufactured by applying a magnetic paint made of magnetic powder, binder resin, etc. onto a support and drying it.

In the magnetic layer of such a magnetic recording medium, the inclusion of trihydric alcohol fatty acid ester together with an isocyanate compound in the binder resin was disclosed in Japanese Patent Publication No. 41-18.
This is shown in Publication No. 062, etc.

Esters of trihydric alcohols such as glycerin and fatty acids are used as lubricants in magnetic recording media of the type in which magnetic powder and binder resin are kneaded and coated on a support to form a magnetic layer. However, glycerin ester alone does not have sufficient lubricating effect. On the other hand, as higher density is required, especially for VH3 and β format videotapes and 8m videotapes, conventionally known lubricant systems such as basic fatty acids and fatty acid esters are used. (ester of -hydric alcohol and monobasic fatty acid) is no longer sufficient. In particular, still image durability and running stability such as jitter and skew characteristics were insufficient.

Object of the Invention An object of the invention is to provide a magnetic recording medium that has a magnetic layer with good lubricity, excellent still image durability, running stability, and S/N ratio.

20 Structure of the Invention and Its Effects That is, the present invention relates to a magnetic recording medium in which a magnetic layer contains a fatty acid and a glycerin ester.

According to the present invention, since a glycerin ester and a fatty acid are used together, while exhibiting the respective characteristics of both,
It is possible to improve the lubrication effect by offsetting the defects that occur when used alone, and to improve still image durability, running stability, S/N ratio, etc.

The blending ratio of these two components is glycerin ester: fatty acid = (1:10) to (3:1) (desirably, (
More preferably, the ratio is 1:5) to (2:1). If the fatty acid content is too low outside this range, the coefficient of static friction will increase,
Furthermore, if the amount of glycerin ester is too small, the coefficient of dynamic friction tends to increase. The amount of glycerin ester added is preferably o, oos to 2 parts by weight per 100 parts by weight of magnetic powder, and
Even better is 1 to 1 part by weight of 0O. If the amount of ester is outside this range and the amount of ester decreases, the effect of improving running performance will be poor, and if the amount increases, the ester will easily seep out and the output will decrease.

Preferably, the glycerin ester is represented by the following general formula.

Tongue H2-0-R' (However, at least one of R1, R2, and R3 is a monobasic fatty acid residue having 6 to 30 carbon atoms, and the others may be hydrogen atoms, and R1 ,,Rt,R3
may be the same or different. More preferably, at least one monobasic fatty acid residue of R1, Rg, and R3 has 10 to 22 carbon atoms. ) Specifically, the glycerin ester may be as follows.

(1) Ester of glycerin and palmitic acid (16 carbon atoms) (however, the ester may be a monoester, diester, or triester (the same applies hereinafter)) (2) Glycerin and stearic acid (carbon (3) Esters of glycerin and oleic acid (18 carbon atoms and containing 1 unsaturated carbon-carbon double bond) (4) Glycerin and linoleic acid (18 carbon atoms and containing 1 unsaturated carbon-carbon double bond) (5) Olive oil (a natural product, a mixture of various glycerin esters) (6) Ester of glycerin with lauric acid (10 carbon atoms) (7) Ester of glycerin and myristic acid (14 carbon atoms) (8) Ester of glycerin and valmitic acid (16 carbon atoms) (9) Glycerin and isostearic acid (18 carbon atoms)
) Ester of glycerin and behenic acid (22 carbon atoms) (11) 2-ethylhexanoic acid triglyceride (
12) Behenic acid monoglyceride (13) Oleic acid stearic acid monodiglyceride (14) Diacetyl capric acid glyceride (15) Diacetyl coconut fatty acid glyceride (16) Acetyl stearic acid glyceride (17) Diacetyl capric acid glyceride (18) Diacetyl coconut fatty acid glyceride ( 19) Caprylic acid monodiglyceride (20) Acetyl stearic acid glyceride (21) Caprylic acid triglyceride (22) Fatty acid (Cs, C+.) Triglyceride or more, even if it is two or more types of glycerin ester or dibasic good. Number of carbon atoms: 6 to 30, even 1
0-22 fatty acids are preferred.

Examples of fatty acids are as follows.

(1) Caproic acid (2) Caprylic acid (3) Capric acid (4) Lauric acid (5) Myristic acid (6) Valmitic acid (7) Stearic acid (8) Isostearic acid (9) Rilunic acid (10) Linoleic acid (11) Oleic acid (12) Elaidic acid (13) Behenic acid (14) Malonic acid (15) Succinic acid (16) Maleic acid (17) Glutaric acid (18) Adipic acid (19) Pimelic acid (20) Azelaic acid (21) Sebacic acid (22) 1,12-dodecanedicarboxylic acid (23)
Octane dicarboxylic acid In the present invention, in addition to the glycerin ester, esters of other polyhydric alcohols such as sorbitan may also be used in combination. Moreover, the -hydric alcohol and fat are as follows.

(1) Oleyl oleate (2) Isocetyl stearate (3) Dioleyl maleate (4) Butyl stearate (5) Butyl palmitate (6) Butyl myristate (7) Octyl myristate (8) Octyl palmitate ( 9) Amyl stearate (lO) amyl palmitate (11) isobutyl oleate (12) stearyl stearate (13) lauryl oleate (14) octyl oleate (15) isobutyl oleate (16) methyl oleate (17) isotridecy oleate (18) 2-ethylhexyl stearate (19)
Methyl stearate (20) 2-ethylhexyl palmitate (21)
Isopropyl palmitate (22) Isopropyl myristate (23) Methyl laurate (24) Cetyl-2-ethyl hexalate (25) Dioleyl adipate (26) Diethyl adipate (27) Diisobutyl adipate (28) Diisodecyl adipate Magnetism of the present invention At least polyurethane can be used as a binder resin for the magnetic layer in the recording medium, and this can be synthesized by reacting a polyol with a polyisocyanate. Polyols that can be used include phthalic acid,
Organic dibasic acids such as adipic acid, azelaic acid, dimerized sulfuric acid, and maleic acid; glycols such as ethylene glycol, propylene glycol, butylene glycol, and diethylene glycol; or trimethylolpropane, hexanetriol, glycerin, and trimethylolethane; Polyester polyol synthesized by reaction with polyhydric alcohols such as pentaerythritol or any two or more polyols selected from these glycols and polyhydric alcohols; or S-caprolactam, α-methyl - Lactone polyester polyols synthesized from lactams such as -1-caprolactam, S-methyl-3-caprolactam, and T-butyrolactam; or polyether polyols synthesized from ethylene oxide, propylene oxide, butylene oxide, etc. .

These polyols are reacted with isocyanate compounds such as tolylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, metaxylylene diisocyanate, etc., resulting in urethanized polyester polyurethanes, polyether polyurethanes, and polycarbonates carbonated with phosgene or diphenyl carbonate. Polyurethane is synthesized.

These polyurethanes are usually produced primarily by the reaction of polyisocyanates with polyols and are also in the form of urethane resins or urethane prepolymers containing free isocyanate groups and/or hydroxyl groups, or containing reactive end groups of these. (for example, in the form of a urethane elastomer).

Since the methods for producing polyurethane, urethane prepolymers, urethane elastomers, curing and crosslinking methods, etc. are well known, detailed explanation thereof will be omitted.

In addition, in the present invention, if a phenoxy resin and/or a vinyl chloride copolymer is contained in addition to the above-mentioned polyurethane as a binder resin, the dispersibility of the magnetic powder will be improved when applied to the magnetic layer, and its mechanical properties will be improved. Strength increases. However, if only the phenoxy resin and/or the vinyl chloride copolymer is used, the layer becomes too hard, but this can be prevented by containing polyurethane, and the adhesion to the support or base layer is improved.

The phenoxy resin that can be used is a polymer obtained by polymerizing bisphenol A and epichlorohydrin, and is represented by the following general formula.

(However, n-shiba 82-13) For example, PKHC manufactured by Union Carbide.

There are PKHHSPKHT, etc.

In addition, the vinyl chloride copolymers that can be used include the following! The molar ratio derived from and m is 95 to 50 mol% for the former unit and 5 to 50 mol% for the latter unit. Further, X represents a monomer residue copolymerizable with vinyl chloride, and represents at least one member selected from the group consisting of vinyl acetate, vinyl alcohol, maleic anhydride, and the like. The degree of polymerization expressed as (l+m) is preferably 100 to 600. If the degree of polymerization is less than 100, the magnetic layer etc. will tend to become sticky, and if it exceeds 6 (IQ), the dispersibility will deteriorate. The copolymer may be partially hydrolyzed.

As the vinyl chloride copolymer, preferably vinyl chloride-
Examples include copolymers containing vinyl acetate (hereinafter referred to as "vinyl chloride-vinyl acetate copolymers"). Examples of vinyl chloride-vinyl acetate copolymers include vinyl chloride-vinyl acetate-vinyl alcohol, vinyl chloride-vinyl acetate-maleic anhydride copolymers, and vinyl chloride-vinyl acetate copolymers. Among these, partially hydrolyzed copolymers are preferred. Specific examples of the above-mentioned vinyl chloride-vinyl acetate copolymers include rVAGHJ, rVYHHJ, and rVMcHJ manufactured by Union Carbide;
“S-LEC C”, “S-RESOC M”, “Denkabinir 100OGJ”, [Denkabinir 10
0OWJ etc. can be used.

In addition to the above, cellulose resins can also be used as binder resins, including cellulose ether,
Cellulose inorganic acid esters, cellulose organic acid esters, etc. can be used. As the cellulose ether, methyl cellulose, ethyl cellulose, etc. can be used. As the cellulose inorganic acid ester, nitrocellulose, cellulose sulfate, cellulose phosphate, etc. can be used. Further, as the cellulose organic acid ester, acetyl cellulose, propionyl cellulose, butyryl cellulose, etc. can be used. Among these cellulose resins, nitrocellulose is preferable.

In addition, regarding the entire binder composition, the ratio of the above-mentioned urethane resin to other resins (total amount of phenoxy resin, vinyl chloride copolymer, etc.) is 90/1 by weight.
Desirably 0 to 40/60, 85/15 to 45
155 has been found to be even more desirable. If the amount of urethane resin is outside this range, dispersion tends to be poor.
Also, if there is a large amount of other resins, surface properties tend to be poor.
In particular, when the concentration exceeds 60%, the physical properties of the coating film become less favorable overall. In the case of vinyl chloride-vinyl acetate,
It can be mixed with the urethane resin with a considerable degree of freedom, and preferably the urethane resin is 15 to 75% by weight.

In addition to the binder resins mentioned above, thermoplastic resins, thermosetting resins, reactive resins, and electron beam curable resins may be used as binder resins for the layers constituting the magnetic recording medium of the present invention.

The thermoplastic resin has a softening temperature of 150°C or less, an average molecular weight of 10.000 to 200,000, and a polymerization degree of about 2.
For example, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, acrylic ester-styrene copolymer, etc. are used.

The thermosetting resin or reactive resin has a molecular weight of 200,000 or less in the state of a coating liquid, and after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition. Moreover, among these resins, those which do not soften or melt before the resin is thermally decomposed are preferable. Specifically, for example, phenol resin, epoxy resin, urea resin,
These include melamine resin, alkyd resin, etc.

Examples of electron beam irradiation-curable resins include unsaturated prepolymers,
Examples include maleic anhydride type, urethane acrylic type, and polyester acrylic type.

In the magnetic recording medium of the present invention, carbon black may be further added to the magnetic layer. It is desirable that this carbon black has electrical conductivity, but carbon black with light-shielding properties may also be added. As such conductive carbon black, for example, Conductex 975 manufactured by Columbia Carbon Co., Ltd. (specific surface area 250 m/g) is used.
, particle size 24 mμ), Conductex 900 (specific surface area 12FM/g, particle size 27 mμ), Cabot Vulcan XC-72 (specific surface area 2
54n? /g, particle size 30 m, u), Raven 1040.
420, #44 made by Mitsubishi Kasei ■, etc. As the light-shielding carbon black, for example, Raben 2000 manufactured by Columbia Carbon Co., Ltd. (specific surface area 190 m/g, particle size 1B
m, 17), 2100.1170.1000, #100, #75, #40, #35, #3 manufactured by Mitsubishi Kasei ■
0 etc. can be used. Carbon black has an oil absorption of 90mj! (DBP)/100 g or more is desirable because it tends to form a strutted structure and exhibits higher conductivity.

The magnetic recording medium of the present invention has, for example, as shown in FIG.
A magnetic layer 2 is provided on a support 1. Further, a BC layer 3 is provided on the opposite side of the magnetic layer 2. Although this BC layer may be provided, it is not necessary to provide it. The magnetic powder used for the magnetic layer 2, especially the ferromagnetic powder, is rF
ex O3, Co containing r FezO= , Fe3O4
, iron oxide magnetic powder such as Go-containing Fe1o4; F e %
Ni,, CO% Fe-N1-CO alloy,
Fe-Mn-Zn alloy, Fe-Ni-Zn alloy, Fe-
Go-Ni-Cr alloy, Fe-Co-N1-P alloy, C
Examples include various ferromagnetic powders such as o-Ni alloys and other metal magnetic powders containing Fe, Ni, Co, etc. as main components. Among these, Co-containing iron oxide and metal magnetic powder are preferable. In addition, the BET value of magnetic powder is 25rd/g or more, and even 30n(/
When the amount is more than g, the effect of adding the glycerin ester and fatty acid of the present invention is significant. The magnetic layer 2 also contains other lubricants (
For example, silicone oil, graphite, molybdenum disulfide, tungsten disulfide, etc.), an abrasive (for example, fused alumina), an antistatic agent (for example, graphite), etc. may be added.

The non-magnetic powder contained in the BC layer 3 includes carbon blank, silicon oxide, titanium oxide, aluminum oxide, chromium oxide, silicon carbide, calcium carbide, zinc oxide,
α-F ex Os, talc, kaolin, calcium sulfate, boron nitrogen, zinc fluoride, molybdenum dioxide, calcium carbonate, etc., preferably carbon black (especially conductive carbon blank) and/or titanium oxide Things can be mentioned.

Further, as the non-magnetic powder, organic powder such as benzoguanamine resin, melamine resin, phthalocyanine pigment, etc. may be added.

Further, the magnetic recording medium shown in FIG. 1 may be provided with an undercoat layer (not shown) between the magnetic layer 2 and the support 1, or may not be provided with an undercoat layer (not shown). Same below). The support may also be subjected to corona discharge treatment. Also,
The 80 layer 3 may also contain the compound according to the present invention.

Further, as the material of the support body 1, plastics such as polyethylene terephthalate and polypropylene, Als Z
Metals such as n, glass, BN, Si carbide, ceramics such as porcelain, earthenware, etc. are used.

In addition, when coating and forming the above-mentioned magnetic layer, etc., it is desirable to add a predetermined amount of polyfunctional isocyanate as a crosslinking agent to the coating material in order to strengthen the magnetic layer. In addition to the polyfunctional polyisocyanates mentioned above, examples of such crosslinking agents include
Triphenylmethane triisocyanate, tris-(p
-isocyanate phenyl) thiophosphite, polymethylene polyphenylisocyanate, etc., methylene diisocyanate type and tolylene diisocyanate type are preferable. Note that when the magnetic layer is cured by electron beam irradiation or the like, the addition of the isocyanate compound may be omitted, but it may be added.

FIG. 2 shows other magnetic recording media.
A 00 layer 4 is provided on the magnetic layer 2 of the illustrated medium. This 00 layer 4 is provided to protect the magnetic layer 2 from damage, etc., and for this purpose, it needs to have sufficient slipperiness.

Therefore, as the binder resin for the 00 layer 4, the urethane resin used for the magnetic layer 2 described above is used (preferably in combination with a phenoxy resin and/or a vinyl chloride copolymer). The surface roughness of the 00 layer 4 is preferably Ra≦0.01 μm and Rmax≦0.13 μm, especially in relation to color S/N. In this case, the surface roughness of the support 1 is Ra≦0.
．． 01μmSRmax≦0.13. um, and it is desirable to use a smooth support 1.

FIG. 3 shows a magnetic recording medium configured as a magnetic disk, with magnetic layers 2.00 similar to those described above on both sides of the support 1.
Layers 4 are provided, and the 00 layer 4 may contain a binder resin containing the above-mentioned urethane resin as a main component.

E, Example Hereinafter, the present invention will be explained with reference to specific examples.

The components, proportions, order of operations, etc. shown below may be changed in various ways without departing from the spirit of the invention.

After dispersing the ingredients shown in Table 1, apply 1μ of this magnetic paint.
After filtration with an M filter, 5 parts of polyfunctional isocyanate was added, coated on a support to a thickness of 5 μm, supercalendered, and slit to a width of 172 inches to make a videotape (corresponding to each example and comparison number). And so. however,
The numbers after the second column in Table 1 represent parts by weight, and
"Actual" after 41i1 represents an example, and "ratio" represents a comparative example.

Table-1 The following measurements were made for each tape.

Chroma S/N: Color video noise meter
Measured using 925D/IJ.

Rumi S/N: Same as above.

Jitter value: Using a VTR jitter meter rMK-612AJ manufactured by Meguchi Electronics Co., Ltd., each jitter was measured after 0 and 100 runs at 30° C. and 80% RH under high temperature and humidity.

Still image lifespan: Shows the time in minutes for a still image to degrade by 2 dB.

The larger the value, the higher the durability and wear resistance of the magnetic recording medium.

The performance of each example videotape is shown in Table 2.

Margin below, continued on next page.

Table 2 However, for actual-1 and actual-2, the value of ratio-1 was set to 0, and for actual-3, the value of ratio-2 was set to 0.

The above results show that the tape performance is significantly improved by adding the glycerin ester and fatty acid of the present invention to the magnetic layer based on the present invention.

[Brief explanation of drawings]

The drawings illustrate embodiments of the invention, and FIGS. 1, 2, and 3 are enlarged cross-sectional views of a portion of a magnetic recording medium from each side. In addition, in the symbols used in the drawings, 2...
Magnetic layer 3: Back coat layer (BC layer) 4: Overcoat layer (QC layer). Agent: Patent Attorney Hiroshi AisakaFigure 1Figure 2Figure 3

Claims (1)

[Claims] 1. A magnetic recording medium in which a magnetic layer contains a fatty acid and a glycerin ester.