JPH01112527A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the travelling performance and durability of a magnetic recording medium having a magnetic layer on the surface of the substrate by incorporating a fluorine-contg. ester compd. into the front and/or rear side of the medium. CONSTITUTION:A fluorine-contg. ester compd. represented by formula I, II or III (where each of a, b and c is an integer of 0-100, X is H or F and each of n and m is an integer of 0-50) is incorporated into the front and/or rear side of a magnetic recording medium having a magnetic layer on the surface of the substrate. The resulting magnetic recording medium has smaller jitter and longer still life than the conventional magnetic recording medium and the top of the magnetic layer is hardly scratched, so the resulting magnetic recording medium has superior travelling performance and durability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium, and more particularly, to a magnetic recording medium with excellent running properties and durability.

[Conventional technology]

In general, magnetic recording media are made by binding magnetic powder together with a binder component onto a base film, or by depositing ferromagnetic metals or their alloys on a base film by vacuum deposition, etc. The magnetic layer is likely to be worn out due to violent sliding contact with the magnetic head and the like. In addition, in recent years, base films with extremely good smoothness have been used for the purpose of improving recording density, and therefore the coefficient of friction with guide rolls and the like is large and running tends to become unstable.

For this reason, for example, a lubricant layer made of a lubricant such as higher fatty acid, fatty acid ester, paraffin, or silicone oil is provided on the surface of the magnetic layer or the back surface of the substrate to improve running performance and durability. There is. (JP-A-58-80132, JP-A-62-1119, JP-A-61-104318) [Problems to be solved by the invention] However, these higher fatty acids, fatty acid esters, paraffin, silicone oil, etc. Although the use of lubricants improves running performance and durability, fully satisfactory results have not yet been obtained.

(Means for Solving the Problems) This invention was made as a result of various studies in view of the current situation, and is based on the formula % (where a, b and C are integers from 0 to 100,
is H or F, and n and m are integers from 0 to 50. ) By including a fluorine-containing ester compound represented by the formula on the front or back surface, or both the front and back surfaces of a magnetic recording medium having a magnetic layer on the surface, the coefficient of friction against the magnetic head or guide pin, etc. is lowered, and the running performance and It has sufficiently improved durability. In addition, aliphatic lubricants, fluorine-based lubricants, silicone-based lubricants,
By using at least one kind of lubricant selected from hydrocarbon-based lubricants in combination with a fluorine-containing ester compound, running properties and durability are further improved.

The fluorine-containing ester compound used in this invention has an excellent lubricating effect, and the contained fluorine can form a low-energy surface, so it can be used to form a protective layer on the magnetic layer. As a result, the excellent lubricating effect of these fluorine-containing ester compounds is fully exhibited, blocking can be well suppressed, and the coefficient of friction on the surface of the magnetic layer is sufficiently reduced, improving running performance and durability. sufficiently improved.

In addition, a Barafco-1 layer may be formed directly on the back surface of the substrate on which a magnetic layer has been formed using the above-mentioned fluorine-containing ester compound, or this type of layer may be further formed on the back coat layer already formed on the back surface of the substrate. When the back coat layer is formed using the fluorine-containing ester compound, the friction coefficient of the back coat layer is sufficiently reduced, blocking is also suppressed, and running properties and durability are sufficiently improved.

As such fluorine-containing ester compounds, those represented by the formula (%) are preferable, used alone or in combination
Used in combination with more than one species. a, b in these formulas
and C are integers from 0 to 100, n and m are preferably integers from 0 to 50, and a, b, and C are thicker than 100 (if n and m are larger than 50, sharpness will occur; if n and m are larger than 50, The coefficient of friction increases.

Specific examples of such fluorine-containing ester compounds include CH3(CH,)lICoo(CFri?CF3cF, (
cF, ), coO(CFz)tcF3CFz(CFz)
t(CHz)zCOO(CHz)1□CH.

Examples include.

Furthermore, lubricants such as aliphatic lubricants, fluorine-based lubricants, silicone-based lubricants, and hydrocarbon-based lubricants have excellent lubrication functions and are highly compatible with the above-mentioned fluorine-containing ester compounds. Therefore, when these lubricants are used in combination with the above-mentioned fluorine-containing ester compound, the lubricating effects of both are sufficiently exhibited, the coefficient of friction is sufficiently reduced, and running properties and durability are further improved.

Such aliphatic lubricants, fluorine-based lubricants, silicone-based lubricants, and hydrocarbon-based lubricants include fatty acids such as lauric acid, myristic acid, valmitic acid, and stearic acid;
Metal salts of fatty acids such as zinc stearate and cobalt stearate; fatty acid esters such as n-butyl stearate and octyl myristate; aliphatic alcohols such as stearyl alcohol and myristyl alcohol; perfluoropolyethers and perfluoroalkylbories. Suitable examples include fluorine-based lubricants such as '-chill, silicone-based lubricants such as silicone oil and modified silicone oil, and hydrocarbon-based lubricants such as paraffin, squalane and wax. Used in combination with fluorine-containing ester compounds.

As described above, when these lubricants are used in combination with the above-mentioned fluorine-containing ester compound, the weight ratio of both lubricants to fluorine-containing ester compounds is 0.01:1 to 1:0.01. It is preferable to keep it within the range of .

Such a fluorine-containing ester compound is dissolved in a suitable solvent such as Freon, and the resulting solution contains a magnetic layer formed on the substrate, the back surface of the substrate, and a back coat layer formed on the back surface of the substrate. , by dipping a protective layer formed on the magnetic layer on the substrate, or by coating or spraying the solution on the surface of the magnetic layer, the back surface of the substrate, the back coat layer, the protective layer, etc. It is deposited on the magnetic layer, the back surface of the substrate, the back coat layer, and the protective layer. When applied, it is preferable that the dry thickness of the coating is within the range of 10 to 200 mm (thinner than this, the desired effect will not be obtained, and if it is too thick, it will cause a decrease in output or dropout). Furthermore, when a fluorine-containing ester compound and the above-mentioned lubricant are used together, both are dissolved in a suitable solvent such as Freon, and coated on the magnetic layer, the back surface of the substrate, the back coat layer, and the protective layer in the same manner as above. It will be worn.

When applied, the total coating thickness for both is 10 to 10% in dry thickness.
It is preferable that the thickness is within the range of 200 people.If it is thinner than this, the desired effect cannot be obtained, and if it is too thick, it may cause a decrease in output or dropout.

The magnetic layer formed on the substrate is made of 7 FezO3 powder,
Fe, O, powder, Co containing 7 Fezes powder, Co
A magnetic paint is prepared by mixing and dispersing magnetic powders such as FexO4 powder, Cr (H powder, Fe powder, Co powder, Fe-Ni powder, etc.) together with a binder resin and an organic solvent, and this magnetic paint is applied onto a substrate. , dry or C
o, Ni5Fe, Co-Ni, Co-Cr, Co-PS
It is formed by depositing a ferromagnetic material such as Co--Ni--P on a substrate by means such as vacuum evaporation, ion blating, sputtering, plating, or the like.

In addition, for the bank coat i formed on the back surface of the substrate, a paint for the back coat layer is prepared by mixing and dispersing fillers such as red iron, barium sulfate, calcium carbonate, and carbon black together with a binder resin and an organic solvent. This back coat layer coating material is applied to the back surface of a substrate on which a magnetic layer is formed, and then dried.

Magnetic recording media include various types of structures that come into sliding contact with a magnetic head, such as magnetic tapes having synthetic resin films such as polyester films as bases, magnetic disks and magnetic drums having disks or drums as bases.

〔Example〕

Next, embodiments of the invention will be described.

Examples 1 to 3 A 12 μm thick polyester film was loaded into a vacuum evaporation device, and cobalt was heated and evaporated under a vacuum of 5×10 −’ Torr to form a 0.2 μm thick ferromagnetic metal thin film made of cobalt on the polyester film. formed a layer.

Next, on the back side of the polyester film on which the ferromagnetic metal thin film layer was formed, the following paint for a back coat layer was applied and dried to form a bank coat layer with a thickness of 1.0 μm.

Back coat layer paint Carbon black 300 parts by weight Nitrocellulose 100 Polyurethane resin
70 Trifunctional low molecular weight isocyanate-3
0 Compound cyclohexanone 750 Toluene
750 Next, a 0.5% by weight Freon solution of a fluorine-containing ester compound shown in Table 1 below was applied onto the ferromagnetic metal thin film layer and the back coat layer so that the dry thickness of both was 80%. After drying, a protective layer and a back coat layer made of a fluorine-containing ester compound were formed on the magnetic layer and the previously formed lower back coat layer, and the tape was cut to a predetermined width to produce a magnetic tape.

Examples 4 to 6 Fe magnetic powder 80 parts by weight Vinyl chloride-vinyl acetate-vinyl 16 alcohol copolymer polyurethane resin 1 Trifunctional low molecular weight isocyanate 1 Compound lubricant 1 Methyl isobutyl ketone 60 Toluene
60 This composition was mixed and dispersed in a ball mill for 72 hours to prepare a magnetic paint.
The magnetic layer was coated on a polyester film having a dry thickness of 6 μm and dried to form a magnetic layer.

Next, a back coat layer was formed on the back side of the polyester film on which the magnetic layer was formed in the same manner as in Example 1,
Furthermore, a protective layer and an upper back coat layer each made of a fluorine-containing ester compound having a dry thickness of 80 mm were formed on the magnetic layer and back coat layer in the same manner as in Example 1, and then cut to a predetermined width. and created magnetic tape.

Examples 7 to 9 CO content 7 FezOz 60 parts by weight Vinyl chloride-vinyl acetate-vinyl to L alcohol copolymer polyurethane resin 4 Trifunctional low molecular weight isocyanate 1 Compound lubricant 1 Methyl isobutyl ketone 60 Toluene
60〃This composition was mixed and dispersed in a ball mill for 72 hours to prepare a magnetic paint.
A magnetic layer was formed by coating and drying on a .mu.m polyester film to a dry thickness of 6 .mu.m.

Next, a back coat i was formed on the back side of the polyester film on which the magnetic layer was formed in the same manner as in Example 1,
Furthermore, a protective layer and an upper back coat layer each made of a fluorine-containing ester compound having a dry thickness of 80 mm were formed on the magnetic layer and back coat layer in the same manner as in Example 1, and then cut to a predetermined width. and created magnetic tape.

Example 10 In forming the protective layer and back coat layer in Example 1, a 0.25 wt% Freon solution of Fomblin Z25 (perfluoropolyether manufactured by Montefluos) was added to the 0.5 it% Freon solution of the fluorine-containing ester compound. This mixed solution is applied onto the magnetic layer and the lower back coat layer to a dry thickness of 80 mm, and dried to form a protective layer consisting of a fluorine-containing ester compound and Fomblin Z25. A magnetic tape was prepared in the same manner as in Example 1, except that the magnetic layer and the back coat layer were formed on the magnetic layer and the previously formed lower back coat layer.

Example 11 A magnetic tape was produced in the same manner as in Example 1, except that the formation of the upper back coat layer made of a fluorine-containing ester compound on the back coat layer was omitted.

Example 12 A magnetic tape was produced in the same manner as in Example 2, except that the formation of the upper back coat layer made of a fluorine-containing ester compound on the back coat layer was omitted.

Example 13 A magnetic tape was produced in the same manner as in Example 3, except that the formation of the upper back coat layer made of a fluorine-containing ester compound on the back coat layer was omitted.

Example 14 A magnetic tape was produced in the same manner as in Example 4, except that the formation of the upper back coat layer made of a fluorine-containing ester compound on the back coat layer was omitted.

Example 15 A magnetic tape was produced in the same manner as in Example 5, except that the formation of the upper back coat layer made of a fluorine-containing ester compound on the back coat layer was omitted.

Example 16 A magnetic tape was produced in the same manner as in Example 6, except that the formation of the upper back coat layer made of a fluorine-containing ester compound on the back coat layer was omitted.

Example 17 A magnetic tape was produced in the same manner as in Example 7, except that the formation of the upper back coat layer made of a fluorine-containing ester compound on the back coat layer was omitted.

Example 18 A magnetic tape was produced in the same manner as in Example 8, except that the formation of the upper back coat layer made of a fluorine-containing ester compound on the back coat layer was omitted.

Example 19 A magnetic tape was produced in the same manner as in Example 9, except that the formation of the upper back coat layer made of a fluorine-containing ester compound on the back coat layer was omitted.

Example 20 A magnetic tape was produced in the same manner as in Example 10, except that the formation of the upper back coat layer made of a fluorine-containing ester compound on the back coat layer was omitted.

Comparative Example 1 In the formation of the protective layer and the upper back coat layer in Example 1, n-amyl stearate shown in Table 1 below was used instead of the 0.5% by weight Freon solution of the fluorine-containing ester compound. The same procedure as in Example 1 was used except that a 0.5% by weight methyl ethyl ketone solution was used to obtain
A protective layer and an upper back coat layer were formed, and a magnetic tape was attached.

Comparative Example 2 In the formation of the protective layer and the upper Barafco-1 layer in Example 4, n-amyl stearate shown in Table 1 below was used instead of the 0.5% by weight Freon solution of the fluorine-containing ester compound. The same procedure as in Example 4 was used except that a 0.5% by weight methyl ethyl ketone solution was used.
A protective layer and an upper back coat layer were formed to produce a magnetic tape.

Comparative Example 3 In the formation of the protective layer and the upper back coat layer in Example 7, 0.5% by weight freon solution of the fluorine-containing ester compound was replaced with 0% n-amyl stearate shown in Table 1 below. A thickness of 80 mm was prepared in the same manner as in Example 7 except that a .5% by weight methyl ethyl ketone solution was used.
A protective layer and an upper back coat layer were formed to create a magnetic tape.

Comparative Example 4 In Comparative Example 1, stearic acid n on the back coat layer
- A magnetic tape was produced in the same manner as in Comparative Example 1, except that the formation of the upper back coat layer made of amyl was omitted.

Comparative Example 5 In Comparative Example 2, stearic acid n on the back coat layer
- A magnetic tape was produced in the same manner as Comparative Example 2 except that the formation of the upper back coat layer made of amyl was omitted.

Comparative Example 6 In Comparative Example 3, stearic acid n on the back coat layer
- A magnetic tape was produced in the same manner as in Comparative Example 3, except that the formation of the upper bank coat layer made of amyl was omitted.

Table 1 Regarding the magnetic tapes obtained in each example and comparative example,
Jitter characteristics and durability were tested.

In the jitter characteristic test, the obtained magnetic tape was loaded into a video deck, a video signal was recorded and played back, and the interval between 15.75 KHz horizontal synchronization signals of the playback signal was read.
This was done by measuring the shift in the interval of horizontal synchronization signals for 1 second after 100 days. In addition, in the durability test, the obtained magnetic tape was loaded into a video deck, video signals were recorded and played back under the conditions of 20°C, 150% RH, and the time until the output decreased by 3 dB, that is, the still life was measured. I went. Furthermore, the scratches on the surface of the magnetic layer after the durability test were visually observed, and the case where no scratches were observed was evaluated as (A), and the case where even slight scratches were observed was evaluated as (B).

Table 2 below shows the results.

Table 2 [Effects of the Invention] As is clear from Table 2 above, all of the magnetic tapes obtained by the present invention (Examples 1 to 20) are comparable to conventional magnetic tapes (Comparative Examples 1 to 6). However, the jitter characteristics are small, the still life is long (and there are fewer scratches on the magnetic layer surface,
This shows that the magnetic recording medium obtained by the present invention has further improved running properties and durability.

Patent applicant: Hitachi Maxell, Ltd. ４　’　−−−＋　1 L, l+, , −’+−

Claims (1)

[Scope of the Claims] 1. A magnetic recording medium having a magnetic layer on the surface of the substrate, characterized in that a fluorine-containing ester compound is contained on the front or back surface or both the front and back surfaces of the magnetic recording medium. 2. The fluorine-containing ester compound has the formula CF_2XC_nF_2_n(CH_2)_aCOO(
CH_2)_cCH_3 or CF_2XC_nF_2_n(CH_2)_aCOO(
CH_2)_bC_mF_2_mCF_2X or CH_3(CH_2)_cCOO(CH_2)_bC_
nF_2_nCF_2X (however, a, b and c are integers from 0 to 100, X is H or F, n and m are 0
is an integer between and 50. ) The magnetic recording medium 3 according to claim 1, which is a fluorine-containing ester compound represented by At least one selected from silicone lubricants and hydrocarbon lubricants
The magnetic recording medium according to claims 1 and 2, which contains one or more lubricants.