JPH02265013A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the recording medium having the good durability of a magnetic layer by using a vinyl chloride resin having -SO3M (where M: alkali metal) and epoxy group as a binder component and oxyacid ester as a lubricant. CONSTITUTION:This magnetic recording medium is formed by applying the magnetic layer formed of magnetic metallic powder, binder and lubricant on a nonmagnetic base. The vinyl chloride resin having the -SO3M (where M: alkali metal) and the epoxy group in the molecular chain, for example, a polyurethane resin, is used as the binder for this magnetic metallic powder, by which the dispersibility of the magnetic metallic powder is improved and the self- decomposing property of the binder is lowered. Further, the oxyacid ester is used as the lubricant. Since this lubricant is smaller in the effect as the plasticizer of the magnetic layer as compared to the conventional lubricant composed of a fatty acid and fatty acid ester, the degradation in the strength of the coated film of the magnetic layer is lowered and the durability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media, and more particularly to improvements in the binders and lubricants of No. 7.

[Conventional technology]

Conventionally, magnetic recording media using metal magnetic powder.

As a binder, mainly vinyl chloride-vinyl acetate copolymer,
@Fatty acids or fatty acid esters are mainly used as lubricants.

Recently, with the increase in recording density of magnetic recording media.

In the above-mentioned conventional binder system and 114 lubricant system, the dispersion of the metal magnetic powder is insufficient. The i-film strength is low, and in video tapes and the like, there are frequent drawbacks such as inferior durability such as steel durability, or clogging of the magnetic head or staining of the magnetic head, causing dropout.

[Problem that the invention seeks to solve]

The object of the present invention is to solve the drawback of the above-mentioned conventional products, such as peeling of the coating film of the magnetically friendly layer, and thereby provide a highly durable and robust magnetic recording medium.

[Means to solve the problem]

By using a molecular binder iC-805M, a hawkified vinyl co-electrolyte containing an epoxy group, and a polyurethane resin as a binder for metal magnetic powder.

As a 6° Ic lubricant that improves the dispersibility of metal magnetic powder and reduces the self-degradability of the binder, the general formula % formula % (R and R are straight carbon atoms with 11 to 17 carbon atoms, and 9 has a branch) It was found that saturated or unsaturated hydrocarbon groups).

As a vinyl chloride-based coelectrolyte containing -805M and an epoxy group used in the present invention, r! :6 Commercial product manufactured by Nippon Seon Co., Ltd. Examples include MR, 11O, A4R120.

-8Osbli and epoxy groups have extremely high affinity with metal magnetic powder compared to conventionally used resins having hydroxyl groups. Therefore, the dispersibility of the magnetic powder is sufficiently improved, and the magnetic powder is firmly bonded. Furthermore, the epoxy group easily binds to chlorine ions, which are thought to act as catalysts during the self-decomposition of PVC-based copolymer, and removes chlorine ions from the system, thereby suppressing the self-decomposition of the binder. I believe.

In addition, when an oxyacid ester is used as a lubricant, the effect as a plasticizer for the magnetic layer is smaller than when the conventional fatty acid and fatty acid ester are used as a lubricant, so there is less decrease in the strength of the coating film of the magnetic layer. , its durability is excellent.

〔Example〕

Example (C) of the present invention will be described below.

Example 1 Ferromagnetic metal powder (coercive force 16000@, SRET=5
0g/g) 80 parts by weight-8
OsK and epoxy-containing PVC resin (MRIIO manufactured by Nippon Zeon Co., Ltd.) 10 parts by weight Polyurethane resin 6 parts by weight Trifunctional low molecular weight incyanate compound 4 parts by weight Carbon black 4 parts by weight Arunna 6 parts by weight Benzoguanamine 1 part by weight HO (CH2) u
C00(CHx) 13 CHI 4 i[f
fi part cyclohexycine 120 weight parts toluene 120 weight parts Above:
A magnetic paint was prepared by mixing and dispersing the M composition in a sand mill, and this was coated on a polyethylene terephthalate film (V-) with a thickness of about 10 μm. After drying.

A magnetic tape was produced by calendering and cutting into 811JE width.

Example 2 In Example 1, -8OsK and epoxy group-containing PVC resin were replaced. -8OaNaOJ: Vc as in Example 1 except that the same amount of epoxy group-containing PVC resin was used.
A magnetic tape was produced.

Example 3 Actual Example 3.1 FI Oite, f(0(CH2) 18
COO (CHz) Ill VCHO (instead of CHs)
A magnetic tape was produced in the same manner as in Example 1, except that CH2) rcOo(CIllz) 11CII3 was used for Dokeidan.

Comparative Example 1 In Example 11/C, the same amount of chloride, vinegar, and vinyl alcohol copolymer (manufactured by UCC, VAGH) was used in place of -8OaK and epoxy group-containing PVC resin, and the same as in Example 1 except for the following. A magnetic tape was produced using the following method.

Comparative example 2 Actual flow example 1 iC Oite HO (CH Mayuzumi) 13COO (C
Instead of HI ) xscHs, CI(s (CHz
) ucOOH4 direct weight part and CHs (CHI) 1
Using 1.5 parts by weight of 6COOC4Hs, a magnetic tape was prepared in the same manner as in Example 1, except for the following: t0 The squareness ratio and still durability of the magnetic tapes obtained in each Example and Comparative Example were measured.

The squareness ratio is C measured using VSM, and the still durability is measured using an 8-fight video camera, and the playback output is 1 to 1. Measure the time it takes for the temperature to drop by 6dB.

The squareness ratio is a characteristic that is regarded as an index of the dispersibility of magnetic powder.

〔Effect of the invention〕

As explained above, a magnetic recording medium using 1805M and Evoquin group-containing vinyl chloride resin as a binder component and an oxyacid ester as a lubricant has a good dispersion of metal-derived powder. It is clear that the durability of the magnetic layer is improved in both cases.

Applicant: Hitachi Maxell, Ltd. Representative Atsushi Mizu

Claims (3)

[Claims] (1) In a magnetic recording medium in which a magnetic layer consisting mainly of metal magnetic powder, a binder, and a lubricant is coated on a nonmagnetic support, the binder component is -SO_3M (M is an alkali metal) and an epoxy group. A magnetic recording medium characterized in that a vinyl chloride resin having the following properties is used, and an oxyacid ester is used as a lubricant. (2) The oxyacid ester has the general formula HO-R-COOR (R and R^1 are linear or branched saturated or unsaturated hydrocarbon groups having 12 to 18 carbon atoms). The magnetic recording medium according to claim 1, wherein the magnetic recording medium is an aliphatic oxyacid ester represented by the following formula. (3) Metal magnetic powder has a BET specific surface area of 40 m^2/g
The magnetic recording medium according to claim 1, wherein the magnetic recording medium is a metal magnetic powder having a coercive force of 1000 Oe or more.