JPS61133027A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the adhesive property of the titled medium to a magnetic layer, to strengthen a topcoat layer, and to improve the abrasion resistance and durability by forming the topcoat layer incorporated with a monomeric compd. having a specified polar group in the molecule and a curing agent on the magnetic layer. CONSTITUTION:A monomeric compd. having, in the molecule, >=2 kinds of polar groups selected from -PO(OM)2, -OPO(OM)2, -SO3M, -OSO3M, -COOM -NH2, -OH, and -CONH- (where M is H, Li, Na, K, NH2, or NH4) is used as the monomeric compd. to be used in a topcoat layer. The >=2 kinds of polar groups are excellently adsorbed on the surface of a magnetic layer, and suffi ciently cross-linked with a curing agent. For example, monomeric compds. shown by formulas I, II, III, IV, and V [where R is a 8-22C hydrocarbonic group, and (n) is a 3-12 integer] and a monomeric compd. expressed by formula VI are preferably used as the above-mentioned monomeric compd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording medium in which a top coat layer is further provided on a magnetic layer formed on a substrate, and more specifically relates to a magnetic recording medium having excellent durability. Regarding recording media.

[Conventional technology]

In general, magnetic recording media are made by fixing magnetic powder together with a binder component on a base film, or by depositing ferromagnetic metals or their alloys on a base film by vacuum deposition, etc. The magnetic layer is easily abraded due to violent sliding contact with the head, etc., so a material with good abrasion resistance and excellent durability is required.

For this reason, various efforts have been made to improve durability by providing various types of coating layers on the magnetic layer.
No. 0609), a top coat layer is provided by coating a cellulose derivative, an epoxy resin, or a polyamide resin (Japanese Patent Publication No. 5B-9489).

[Problem that the invention seeks to solve]

However, with repeated use of top coat layers formed using low molecular weight compounds such as fatty acids, the top coat layer detaches from the surface of the magnetic layer, deteriorating wear resistance, and causing stains and clogging of the magnetic head. However, products using polymeric compounds such as synthetic resins,
It has poor adhesion to the magnetic layer and does not adhere firmly to the surface of the magnetic layer, resulting in poor abrasion resistance and the formation of stains and clogging of the magnetic head, similar to when the low molecular weight compound described above is used. There is.

[Means for solving problems]

This invention was made as a result of various studies in view of the current situation, and contains -PO(OM)2, -OPO
(0M) 2, - S 03 M, OSo3M, -
COOM, -NH2, -OH, -C0NH- (However, M
is H% L L% N a ,, Ks N H,2
Or NH4. ) By forming on the magnetic layer a top coat layer containing a monomer compound having two or more polar groups selected from the following in combination with a curing agent, the adhesion to the magnetic layer can be sufficiently improved. In addition to firmly adhering to the magnetic layer, the top coat layer is strengthened by sufficient cross-linking with the hardening agent, improving wear resistance and preventing staining or clogging of the magnetic head, making it durable. It has sufficiently improved characteristics.

In this invention, the monomer compound used for the top coat layer has -PO(OM)2, OPO(O
M)2, SO3M, 0503M, -COOM,
-NH2, -OH, -CONH- (where M is H,,L
L Nas K% NH2 or NH4. ) A monomeric compound having two or more polar groups selected from
These two or more types of polar groups are well adsorbed to the surface of the magnetic layer and also cross-linked with the curing agent. Therefore, this type of monomer compound is used together with the curing agent to be included in the top coat layer. When one polar group is adsorbed to the magnetic layer surface, the other polar group is hardened due to the difference in the adsorption property of these two or more types of polar groups to the magnetic layer surface and the crosslinking property with the hardening agent. When one polar group crosslinks with the curing agent, the other polar group adsorbs to the surface of the magnetic layer, sufficiently improving the adhesion of the top coat layer to the magnetic layer. , a strong top coat layer is formed, and a magnetic recording medium with good wear resistance and excellent durability can be obtained.

In such a molecule, P O (OM) x , -0
PO(OM)2,-3O3M, 0303M.

As a monomer compound having two or more polar groups selected from C00M, NH2, OH, -CONH (where M is H-, L1-, Na%K%NH2 or NH4), , for example, general formula % formula %) RCH(CH2)ncooH (9)l 03Na RCH(CH2) n p OOH α0)( H (However, R is a hydrocarbon group having 8 to 22 carbon atoms, and n is 3 to
It is an integer of 12. ) A monomer compound represented by the formula % and a monomer compound represented by the structural formula % are preferably used.

Monomeric compounds having two or more types of polar groups as described above are usually obtained by a method similar to the method for manufacturing surfactants in general, and these two or more types of polar groups introduced in this way are It adsorbs well to the surface of the magnetic layer and also cross-links well with the curing agent.

Therefore, when a monomer compound having two or more of these polar groups is used in combination with a curing agent in the top coat layer, the adsorption property of these two or more polar groups to the magnetic layer surface and the crosslinking property with the curing agent. Due to the difference in Since these two or more types of polar groups are adsorbed to the surface of the magnetic layer, the adhesion of the top coat layer to the magnetic layer is sufficiently improved, and a tough top coat layer is formed to improve the wear resistance of the top coat layer. A magnetic recording medium that is sufficiently improved and has excellent durability can be obtained.

Curing agents used in combination with such monomeric compounds having two or more types of polar groups in the molecule include - cross-linking agents such as two or more isocyanate groups, epoxy groups, or ethyleneimine rings in the molecule; Isocyanate compounds, epoxy compounds, and ethyleneimine compounds having a functional group are preferably used, and specific examples include Coronae) L (manufactured by Nippon Polyurethane Industries Co., Ltd., 3).
Functional Image Molecular Weight Isocyanate Compound), Epicron 8
00 (manufactured by Dainippon Ink & Chemicals Co., Ltd., a bifunctional bisphenol type epoxy resin), PAZ-33 (manufactured by Nippon Shokubai Kagaku Co., Ltd., a trifunctional modified tyrene imine compound), and the like. When these curing agents are used in combination with the monomer compounds having two or more types of polar groups in their molecules, they form a good cross-linking bond with the remaining polar groups of the monomer compounds that are not adsorbed to the surface of the magnetic layer. Therefore, a tough top coat layer is formed and wear resistance is sufficiently improved. Therefore, the adhesion of the top coat layer to the magnetic layer is sufficiently improved, and the abrasion resistance of the top coat layer is also sufficiently improved.
A magnetic recording medium with excellent durability can be obtained. When these curing agents are used together with the above-mentioned monomer compounds having an acidic polar group such as -303H1-COOH as a crosslinking polar group, the curing agents having an ethyleneimine ring are particularly difficult to use. It is preferable to use a curing agent having an ethyleneimine ring in order to react well with the monomer compound and form a crosslinking bond, and the curing agent has a polar group exhibiting basicity such as -Nl2 or -CONH- as a polar group for crosslinking. When used in combination with the above-mentioned monomer compounds, it is recommended to use curing agents such as isocyanate compounds and epoxy resins, as curing agents having isocyanate groups and epoxy groups crosslink well with these monomer compounds. is preferable, and when used in combination with the above-mentioned monomer compound having 10H group as a crosslinking polar group, both curing agents are preferably used because they crosslink well. In this case, the top coat layer solution.

It is preferably used because of its good stability. It is preferable to use such a curing agent within the range of 1 to 40% by weight based on the total amount of the top coat agent. If it is too small, the desired effect will not be obtained, and if it is too large, the viscosity of the top coat layer solution will be reduced. The increase becomes significant.

Such a topcoat layer usually contains 2 in the molecules mentioned above.
A monomer compound having one or more polar groups is used in combination with other synthetic resins if necessary, mixed and dispersed with a curing agent, an organic solvent, etc. to prepare a top coat layer solution, and this is applied in advance to a polyester film, etc. The magnetic layer is formed on the magnetic layer formed on the surface of the substrate by coating or spraying and drying, or by dipping the magnetic layer in S or the above-mentioned top coat layer solution. The thickness of such a top coat layer is 0.
If it is thinner than 0.01μ, the desired effect will not be obtained, and if it is thicker than 5μ, the spacing loss will be too large and the electromagnetic conversion characteristics may deteriorate, so it is preferable to keep it within the range of 0.01 to 5μ. More preferably, the thickness is within the range of O,OS to 1μ.

Here, the synthetic resins used in combination when necessary include vinyl chloride resins, vinylidene chloride resins, vinyl acecool resins, cellulose resins, and polyurethane resins, which are generally used as binder resins for magnetic recording media. , polyester resin, acrylonitrile-butadiene copolymer, polyethylene resin, polyamide resin, epoxy resin, polyether resin, acrylic resin, etc. are used in combination.

Organic solvents such as methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, toluene, ethyl acetate, tetrahydrofuran, dioxane, dimethyl formamide, etc. are commonly used to dissolve monomeric compounds and binder resins used in combination if necessary. Each of the organic solvents may be used alone or in combination of two or more.

The magnetic layer formed on the substrate is made of T-Fe2Q3 powder, F
e3O4 powder, Co-containing r-Fe203 powder, Co-containing Fe3O4 powder, Fe powder, C.

Co., Ltd., Co. Ni, Fe, Go-
It is formed by depositing a ferromagnetic material such as NiSCo-Cr, Co-P-, Co-Ni-P, etc. on a substrate by means such as vacuum evaporation, ion blasting, sputtering, or plating.

〔Example〕

Next, embodiments of the invention will be described.

Example Co-containing Fe203 powder 80 parts by weight VAGH
(Manufactured by U, C, C, vinyl chloride 10-vinyl acetate-vinyl alcohol copolymer) Bandex T5201 (Dainippon 8, manufactured by Ink Chemical Industry Co., Ltd., urethane elastomer) Coronate (Nippon Polyurethane 2, manufactured by Kogyo Co., Ltd.) ,
Trifunctional low molecular weight isocyanate compound) Methyl isobutyl ketone 50〃Toluene
50 This composition was mixed and dispersed in a ball mill for 70 hours to prepare a magnetic paint. This magnetic paint was applied to the surface of a 75 μm thick polyester film to a dry thickness of about 1 μm, dried, and surface treated to form a magnetic layer.

Next, on the magnetic layer formed on the surface of this polyester film, a top coat layer solution consisting of the following composition prepared using a monomer compound represented by general formula (1) where n is 3 is applied. Then, it was dried to form a top coat layer, which was then cut into a predetermined width to form a magnetic tape.The thickness of the top coat layer at this time was 0.1 .mu.m.

Top coat layer solution monomer compound 10 parts by weight Coronate 10 〃Methyl isobutyl ketone 500〃Toluene
500 Example 2 In the composition of the top coat layer solution in Example 1,
Magnetic properties were obtained in the same manner as in Example 1, except that the monomer compound represented by general formula (1) was replaced with the same amount of the monomer compound represented by general formula (2), where n was 9. A magnetic tape was formed by forming a layer and a topcoat layer.

Example 3 In the composition of the top coat layer solution in Example 1,
A magnetic layer and a top coat were prepared in the same manner as in Example 1, except that the same amount of the monomer compound represented by Structural Formula (11) was used in place of the monomer compound represented by General Formula (1). By forming layers, a magnetic tape was made.

Example 4 In the composition of the top coat layer hot liquid in Example 1,
Except that the monomer compound represented by general formula (8), where R is an alkyl group having 22 carbon atoms and n is 12, was used in the same amount instead of the monomer compound represented by general formula (1). A magnetic layer and a top coat layer were formed in the same manner as in Example 1 to produce a magnetic tape.

Example 5 In the composition of the top coat layer solution in Example 1,
In place of the monomer compound represented by general formula (1), the same amount of the monomer compound represented by structural formula (11) was used, and in place of Coronate, Epiclon 800 (Dainippon Ink Chemical Co., Ltd. A magnetic layer and a topcoat layer were formed in the same manner as in Example 1, except that the same amount of difunctional bisphenol type epoxy resin was used, and a magnetic tape was produced.

Example 6 A polyester film with a thickness of 12 μm was loaded into a vacuum evaporation apparatus, and cobalt was heated and evaporated under a vacuum of 5×10 −5 Torr to form a ferromagnetic metal thin film layer of cobalt with a thickness of 0.2 μm on the polyester film. Formed. Next, on this ferromagnetic metal thin film layer, in the composition of the hot top coat layer in Example 1, instead of the monomer compound represented by the general formula (1), a compound represented by the general formula α field, n A top coat layer was formed in the same manner as in Example 1, except that the same amount of the monomer compound having 6 was used, and a magnetic tape was produced. The thickness of the top coat layer at this time was 0.1 μm.

Comparative Example 1 A magnetic layer and a top coat layer were formed in the same manner as in Example 1, except that a top coat layer solution having the following composition was used in place of the top coat layer solution in Example 1, and a magnetic tape was produced. . The thickness of the top coat layer at this time was 1 μm.

Top coat layer warm liquid nitrocellulose 7 parts by weight epoxy resin 2 Polyamide resin
1 〃Methyl ethyl ketone 7
00〃Xylene 300〃Comparative Example 2 In the composition of the top coat layer solution in Example 6,
A magnetic layer and a top coat layer were formed in the same manner as in Example 6, except that 1 part by weight of palmitic acid was used instead of the monomer compound represented by general formula (1), and a magnetic tape was produced. . The thickness of the top coat layer at this time is 0.1μ
Met.

Comparative Example 3 A magnetic tape was produced in the same manner as in Example 1 except that the formation of the top coat layer was omitted.

Comparative Example 4 A magnetic tape was produced in the same manner as in Example 6 except that the formation of the top coat layer was omitted.

The durability of the magnetic tapes obtained in each Example and Comparative Example was tested by measuring the number of times the magnetic head passed through the magnetic tape until wear of the magnetic layer, dirt on the magnetic head, and the resulting drop in output became significant. did.

The table below shows the results.

〔Effect of the invention〕

As is clear from the above table, the magnetic tapes obtained in Examples 1 to 6 all had better durability than the magnetic tapes obtained in Comparative Examples 1 to 4, and therefore, the present invention It can be seen that the resulting magnetic recording medium has good adhesion of the top coat layer to the magnetic layer, sufficiently improved abrasion resistance, and excellent durability.

Claims (1)

[Claims] 1. In the molecule: -PO(OM)_2, -OPO(OM)_2, -SO_
3M, -OSO_3M, -COOM, -NH_2, -O
H, -CONH- (However, M is H, Li, Na, K, NH_2 or NH
It is _4. ) A top coat layer comprising a monomer compound having two or more types of polar groups selected from the following and a curing agent that crosslinks with this monomer compound is provided on the magnetic layer. magnetic recording medium