JPS60140532A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enable improvement in running property and durability by having specific aliphat. compds. in a back coat layer. CONSTITUTION:A back coat layer is formed by making combination use of the compd. expressed by the formula I , wherein R<1> and R<3> represent a >=10C aliphatic group, respectively; R<2> denotes (CX2)n; X represents a halogen atom or a hydrogen atom, n is an integer of 1-6; and the compds. expressed by the formulas II, III, IV. The compds. dissolved together with a high polymer binder in a solvent are coated on a base and are dried, by which good running property and durability are obtd. The high polymer compd. which can be used in combination is enumerated by a polyurethane resin, vinyl chloride/vinyl acetate copolymer resin, etc. An isocyanate curing agent is used in conjunction with such high polymer compd. The content of the compd. with respect to the high polymer binder is specified as 1-20wt% and the film thickness of the layer contg. the high polymer compd. is specified as 0.3-1.5mu. The running property and durability of the magnetic tape are improved and the damage such as edge breaking or the like is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to magnetic recording media, and in particular to improving the back coat layer of a magnetic tape having a magnetic layer on the surface of the support and a back coat layer on the back surface of the magnetic tape. This invention relates to a magnetic recording medium with improved runnability, durability, and tape edge folding.

BACKGROUND OF THE INVENTION Magnetic recording media such as magnetic tapes, magnetic sheets, and magnetic disks are widely used in the audio, video, and computer fields. Among these, for example, regarding magnetic tape in the video field, when recording and playing back images, the cassette is loaded into the video deck, and the tape is attached to a guide pole or guide roller. While being guided and traveling, the magnetic head rubs and scans the magnetic head. In order to record images on magnetic tape or reproduce them in this way, in order to improve the sensitivity, especially the output in the high frequency range, the sliding condition of the magnetic tape against the magnetic head should not fluctuate. The surface of the magnetic layer is finished smooth. When this magnetic tape is run on a video deck, the front and back sides of the magnetic tape are rubbed by the guide poles and guide rolls, so the magnetic layer on the front side has been designed to have good sliding properties against the guide poles and guide rolls. If the sliding part of the back side of the magnetic tape is not good against these, excessive tension will be applied to the running magnetic tape, and this will cause the magnetic layer to rub excessively against the magnetic head. So,
Not only does the magnetic layer become damaged and the magnetic powder in the magnetic layer peel off, but the tension at which the magnetic tape is wound fluctuates in strength and the winding pressure fluctuates, causing uneven running of the tape when it is reused. When these things occur, image or electromagnetic conversion characteristics such as skew, jitter, tracking deviation, and S/N deteriorate. Therefore, a bank coat layer is provided on the back side of the magnetic tape.

In particular, recently, video equipment such as VH3 video movies, β movies, etc. has become smaller and more dense, making it easier to carry. As video recording is increasingly being carried out under various circumstances, it is hoped that magnetic tape will also be compatible with these conditions. In other words, the miniaturization and higher density of video equipment requires higher recording density for magnetic tape, but it is necessary to increase the number of tape turns as much as possible for a given tape winding diameter. Along with the use of thinner supports, efforts have been focused on smoothing the magnetic layer, and as a result, supports with increasingly smooth surfaces have come to be used. However, the smoother the surface of the magnetic layer and the support on the opposite side, the worse the running properties and durability of the magnetic tape become. As the tape becomes more complicated, the tape comes into contact with guide poles, guide rolls, etc. more often, and is rubbed more frequently, which not only makes the situation worse, but also makes the tape more likely to be deformed and damaged.

Therefore, a back coat layer is provided on the back side of the magnetic tape, and as described above, this bank coat layer has been devised to improve its sliding properties against the guide poles and guide rolls. Some are contained in the resin layer. Mille is carbon black, titanium dioxide, calcium carbonate, alumina, graphite,
The surface of the bank coat layer is roughened by a coating layer of a liquid in which inorganic powder such as silicon dioxide is dissolved or dispersed in a polymer or a dispersant, thereby reducing the contact area with gaitol etc. and reducing the coefficient of friction. This is to prevent the edges of the tape from folding. For example, JP-A-57-13023
Publication No. 4, JP-A-58-161135, JP-A-Sho 5
No. 7-53825 and Makikai No. 58-2415 both show examples using inorganic powders, and many of these also show those with limited particle sizes.

However, even those using these inorganic powders not only do not provide sufficient slipperiness, but also the bonding force of the particles to the binder to resist when the bank coat layer containing them is rubbed is insufficient. Easy to fall,
Particularly when large particles are mixed in, powder falling is more likely to occur, and when the magnetic layer and back coat layer come into contact when the magnetic tape is wound, the convex parts of the back coat layer may damage the magnetic layer. In addition, the unevenness is also transferred to the magnetic layer, and when the magnetic layer is scanned to reproduce an image, it may impair electromagnetic conversion characteristics such as chroma S/N, which indicates the degree of color noise in the image. Furthermore, the back coat layer may peel off and stain the deck, and metal members such as guide poles that come into contact with the back coat layer of the tape may wear out.

For this reason, the running performance that satisfies recent demands,
It is desired to develop a magnetic recording medium having a durable back coat layer.

OBJECTS OF THE INVENTION An object of the present invention is to provide a magnetic recording medium capable of high-density recording that satisfies the above-mentioned recent demands such as maintaining runnability, excellent durability, and preventing edge breakage. be.

In addition, the coefficient of friction is small, and the S/N is improved by making the magnetic layer uneven.
An object of the present invention is to provide a magnetic recording medium having a back coat layer that does not reduce the magnetic field.

Structure of the Invention The object of the present invention is achieved by providing a back coat layer constituting a magnetic recording medium with a compound represented by the general formula below.

Therefore, the magnetic recording medium of the present invention has a magnetic layer on one side of the support and a bank coat layer on the other side of the support, and the back coat layer has the following general formula (2). It is characterized by having a compound shown in FIG.

General formula ■ R' C0NHR200CR3 Where, l? , R represents an aliphatic group having 10 or more carbon atoms,
R2 represents +CX2-)-, X represents a halogen atom or a hydrogen atom, and n represents an integer of 1 to 6.

Next, the present invention will be explained in detail.

R1 and R3 of the compound represented by the above general formula (■) have 1 carbon number
It is a saturated or unsaturated alkyl group or alkenyl group having 0 or more carbon atoms and preferably 25 or less carbon atoms. Also, R2 is ÷C
represents X2+, X is a halogen atom or 'η hydrogen atom, and n is preferably 1-6. Specific examples of these compounds include the following.

(11CK)121CONHCH2C11200CCI
OH21 (2), C14H C0NHCH2CH20
0CC141129(3) Cl4H29CONHCH
2CH200CC17H55 (41C14+))9CO
NHCH2C■2CH200CC14H29f51 C
17H55CONHCH2CH200CC17H35(
61CzH41CONIC+12CH200'CC2(
J[41(?) CC1BH35CONHCH200C
C1% These compounds can be used alone or in combination of two or more.

When the compound represented by the above general formula I is used in combination with the compounds represented by the following general formulas (1), (2), and (2), even better running properties and durability can be obtained.

General formula ■ □2C/\. □-6□20COR' 1 Here, R4 is a saturated or unsaturated alkyl group having 10 or more carbon atoms and preferably 30 or less carbon atoms.

Specifically, the following compounds are exemplified.

(1) ^ (2) (3) (4) (5) General 2■ Here, R5 represents a saturated or unsaturated alkyl group having 1 ρ or more and preferably 30 or less carbon atoms.

Specifically, the following are exemplified.

(1) (2) (3) (4) (5) General formula ■ Here, R6 has 7 to 21 carbon atoms? Indicates a saturated or unsaturated alkyl group.

Specifically, the following are exemplified.

(1) (2) The specific compounds represented by the general formulas (1) and (2) are commercially available as Emulbon S series manufactured by Toho Chemical.

In addition to the above, examples of lubricants include fatty acids, fatty acid esters, paraffin waxes, metal stones, higher alcohols, fatty acid amines, amide derivatives, fluorine compounds, and silicon compounds.

The above general formula I or this compound and the above general formula ■, ■,
In order to form a back coat layer using the compound shown in (2) in combination, it is usually enough to apply and dry the compound dissolved in a solvent together with a polymeric binder. Further, if these compounds are contained in a layer in which inorganic powder is dispersed in these polymeric binders, even better running properties and durability can be obtained.

Examples of polymer compounds that can be used in combination include polyurethane resins, vinyl chloride-vinyl acetate copolymer resins, cellulose resins, phenol resins, epoxy resins, phenoxy resins, acrylic resins, polyamide resins, nitrocellulose, etc. Polyurethane resins are preferred.

Further, it is preferable to use a commonly used isocyanate-based curing agent in combination with these polymer compounds.

Inorganic powders that can be used in combination include carbon black, graphite, alumina, titanium dioxide, calcium carbonate, calcium oxide, silicon dioxide, tungsten disulfide,
Molybdenum disulfide, boron nitride, iron oxide, manganese oxide,
Examples include zinc oxide.

When the compound represented by the above general formula (1) used in the present invention is used together with the compounds represented by the above general formulas (1), (2), (3) or other lubricants, the content of the mixture relative to the above polymer binder is 1 weight. % to 20% by weight is suitable; if the amount is too much, surface adhesion of the floors containing them will occur, and if it is less than this, the desired lubricity cannot be obtained.

When the compound represented by the above general formula I used in the present invention is used together with the compounds represented by the above general formulas (1), (2), (3) or other lubricants, the mixing ratio is 1:10 to 1.
A range of 0:1 is preferred.

The film thickness of the layer containing the compound represented by the above general formula (1) used in the present invention, or a mixture of this compound and the above general formula (1), (2), (2) or other lubricant, and the above polymer compound is 0.3 to 1.5μ is appropriate.

The film of the compound represented by the above general formula I used in the present invention or a mixture of this and the above general formulas (1), (2), (2) and other lubricants is formed by applying a paint, and this paint is used in the present invention. The amount by weight of the compound of the above general formula or the above mixture thereof is preferably in the range of 0.01% by weight to 1% by weight.

As the organic solvent for these, a single solvent such as toluene, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, etc. or a mixed solvent thereof is used.

To apply this paint, there is a dipping method where the paint is immersed in the paint, a reverse roll method where the paint is applied,
An extrusion method, a knife blade method, a doctor blade method, a gravure printing method, a spray method, etc. are used, and the coating film applied by these methods is dried by an appropriate means.

A ferromagnetic metal thin film and a coated type are used for the magnetic layer in the present invention, and the ferromagnetic metal thin film is Fe5CO%
Metals such as N1 or Fe-Co % Fe-Ni s
C.

-Ni Fe-Co-Ni, Fe-Rh, Fe-
Cu, Go-Cu, Co-Au.

Co-Y, Go-La, Co-Pr, Co-
Gd, Go-3m% Go-Pt.

Ni-Cu% Mn-B1s Mn-3b 5μm
-Al,re-CrsCo-Cr.

Ni-Cr, Fe-Co-Cr, Fe-Co-N
A ferromagnetic alloy such as i-Cr formed into a thin film by vacuum deposition, ion blating, sputtering, etc. is used. The thickness of this metal thin film is preferably about 0.02μ to 5.0μ.

In the case of a coating type TII layer, magnetic powder, binder,
It is composed of antistatic agents, abrasives, dispersants, etc., but the magnetic powder includes r-Fe203, Co-containing r-Fe203, Co-coated r-Pe20B, Fe3O4, Co-containing Co-containing Fe.
Oxide magnetic powder such as 50 Doo, CrO2: Fe, Ni,
Co, Fe-Ni-Co alloy, Fe-Mn-Zn alloy,
Fe-Ni-Zn gold, Fe-Co-Ni-Cr alloy, F
e-Go-Ni-P alloy, Co-Ni alloy etc. Fes N
Examples include various magnetic powders such as metal magnetic powder containing 1% Co as a main component. In addition, binders include thermoplastic resins such as acrylic resins, vinyl chloride-vinyl acetate resins, rubber polymers, thermosetting resins such as phenolic resins, epoxy resins, polyurethane resins, and melamine resins, and unsaturated resins. Examples include polymer type electron beam curable resins. The blending ratio of the magnetic powder and binder is 5 to 400 parts by weight of the binder to 100 parts by weight of the metallic magnetic powder.
Parts by weight, preferably 5 to 50 parts by weight.

The support on which the metal thin film or coated magnetic layer is formed may be a plastic base such as polyester, polyethylene terephthalate, polyimide, polyamide, polyamideimide, polyvinyl chloride, cellulose triacetate, polycarbonate, polyethylene naphthalate, or AllAJ alloy. , 71% TI alloy, or stainless steel.

If the compound of the general formula I and the compounds of the general formulas (■ to ■) used in the present invention are contained together with the binder resin in the back coat layer as described above, the lubricating action of the former and the mechanical properties of the latter can be synergistic. The effect further improves durability.

Note that the term "the back coat layer contains the compound of the above general formula" includes not only the case where the compound is contained within the layer but also the case where the compound is attached to the surface of the layer.

Effects of the Invention As explained above, in the present invention, since the back coat layer contains the compound represented by the above general formula, it is possible to improve the running properties and durability of the back coat layer, thereby improving the running properties of the magnetic tape. , durability can be improved, and damage such as edge bending can be reduced.

Furthermore, when the tape is wound, no traces of pressed particles are left on the magnetic layer, so that the S/N can be prevented from decreasing.

In this way, even when a smooth support is used, the running properties and durability of the magnetic recording medium can be improved, so that the recent demands for magnetic recording media for high-density recording can be met.

EXAMPLES Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 A magnetic tape having a magnetic layer on a polyethylene terephthalate film was prepared in advance.

Next, a coating solution having the composition shown below is coated on the back side of the above film using a lino-slow roll coater and dried to a thickness of 0.
A bank coat layer having a thickness of 8 μm was formed, and this was slotted to a width of 1/2 inch to prepare the magnetic tape of Example 1.

Nitrocellulose (product name: Cellline L-200J manufactured by Daicel) Polyurethane (product name: Nissan 5701 manufactured by J. Nodrich)
2g Polyisocyanate (product name: “Coronate L1” manufactured by Nippon Polyurethane Co., Ltd.) 5
g Exemplified compound (1) of general formula CI) 0.2 g Methyl ethyl ketone -60 g Toluene 100 g Examples 2 to 7 In Example 1, instead of using exemplary compound (1) of general formula Magnetic tapes 2 to 7 were prepared in the same manner as in Example 1 except that magnetic tapes 2 to 7 were used, respectively.

Comparative Example 1 A magnetic tape of Comparative Example 1 was prepared in the same manner as in Example 1 except that stearic acid was used in place of the exemplified compound of general formula (1) (11).

Comparative Example 2 A magnetic tape of Comparative Example 2 was prepared in the same manner as in Example 1 except that (Cs 170 )5P ═O was used in place of the exemplified compound (1) of the general formula (1).

The friction coefficients of the back coat layers of the magnetic tapes of Examples 1 to 7 and Comparative Examples 1 to 2 were measured, and the running properties and repeated durability were measured by actually putting them on a video deck.The results are shown in Table 1. Shown below.

Example 8 Same as Example 1 except that instead of the composition used in Example 1, a dispersion of the following composition containing the compound shown in the Example 8 column of Table 2 was sufficiently dispersed with a sand mill. A magnetic tape of Example 8 was prepared.

Nitrocellulose (product name: "Cellline L-200J" manufactured by Daicel Corporation) 2g Polyurethane (product name: "Nistan 5701" manufactured by J. Gutdrich) 2
g Polyisocyanate (trade name "Coronate LJB" manufactured by Honpolyurethane Co., Ltd.) 5 g Compound in the column of Example 8 in Table 2 0.2 g Calcium carbonate (trade name "Homocal D" manufactured by Shiraishi Kogyo Co., Ltd.) 0 g Methyl ethyl ketone 45 g Cyclohexanone 15 g Toluene 100 g In the table, the units of numbers for each compound indicate g.

Examples 9 to 16 In Example 8, the compounds shown in the respective columns of Examples 9 to 16 of this Table 2 were used instead of the compounds shown in the column of Example 8 of Table 2 in the composition. Magnetic tapes of Examples 9 to 16 were prepared in the same manner as Example 8, respectively.

Comparative Example 3 A magnetic tape of Comparative Example 3 was prepared in the same manner as in Example 8, except that stearic acid was used instead of the compound in the Example 8 column of Table 2.

The back coat layer of each of the magnetic tapes of Examples 8 to 16 and Comparative Example 3 had a friction coefficient similar to that of Examples 1 to 7.
The running properties and repeated durability were measured and the results are shown in Table 3.

(Left space on this page) Table 3 Here, the coefficient of friction is a comparison of the coefficient of dynamic friction and the coefficient of static friction. This friction coefficient was measured using a rotating drum type surface property measuring device manufactured by Shinto Kagaku Co., Ltd. with a load of 30
g, and the rotation speed was 66.9 rpm.

In addition, the running performance is NV-8200 manufactured by Matsushita Electric Co., Ltd.
The recording and playback conditions were visually observed using a camera, and the repetition durability was measured using an HR-7100 manufactured by Victor Company of Japan, by measuring the number of times the image was repeatedly played until the image disappeared.

Note that the above measurements were performed at a temperature of 20° C. and a relative humidity of 60%.

As can be seen from these results, the friction coefficient of the back coat layer containing the compound of general formula I used in the present invention,
The running properties and repeated durability are both better than those of the comparative examples, and it is possible that the running properties and repeated durability can be further improved by further using compounds of general formulas ① to ① and inorganic powder in addition to this compound. Recognize.

December 28, 1982

Claims (1)

[Claims] +11 In a magnetic recording medium having a magnetic layer on one side of the support and a back coat layer on the other side (Ill) of the support, the back coat layer is represented by the following general formula I. A magnetic recording medium characterized by having an alkali compound.General formula I R'C0NHR200CR' Here, R and R represent an aliphatic group having 10 or more carbon atoms, and R
2 represents 1,000Cx2+TI, X represents a halogen atom or a hydrogen atom, and n represents an integer from 1 to 6.