JPH0719359B2 - Magnetic recording medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic recording medium. More specifically, it relates to a coating type magnetic recording medium having an undercoat layer provided between a non-magnetic support and a magnetic layer.

[Conventional technology and its problems]

In recent years, magnetic recording media are required to have a higher recording density. For the purpose of increasing the recording density, improvement of the magnetic layer such as atomization and high packing of the magnetic material and thinning of the magnetic layer is being studied. Has been done. However, when the above-mentioned magnetic layer is improved,
The adhesion of the magnetic layer to the support, the strength of the coating film, etc. tend to decrease, and the durability tends to deteriorate. In order to improve this, conventionally, a method of applying an undercoat liquid obtained by dissolving a polyester resin, a polyurethane resin or the like in an organic solvent onto a substrate has been performed.

However, in the conventionally used undercoating liquid, when the magnetic paint is applied on the undercoating layer formed after coating and drying, the undercoating layer swells or dissolves due to the organic solvent contained in the magnetic paint, so that the magnetic layer and the undercoating layer are not dissolved. The smoothness of the interface of the coating layer is impaired,
Further, this may cause deterioration of the smoothness of the magnetic layer surface. As a result, problems such as a decrease in output and an increase in output fluctuation occur. Therefore, a method in which a polyisocyanate compound is added to the undercoat liquid to crosslink the resin contained in the undercoat liquid to suppress swelling or dissolution by a solvent is used, but it cannot be said that a sufficient effect is obtained yet.

[Means for solving problems]

In view of the present situation, the present inventors have made various investigations, and as a component forming the undercoat layer, a specific resin having a hydroxyl group, a polyisocyanate compound and nitrification cotton, or other than these, an organic metal If one or more compounds selected from the group consisting of compounds and tertiary amine compounds are used, swelling or dissolution of the magnetic paint in a solvent can be sufficiently suppressed, and good surface properties and durability can be obtained. The present invention has been completed by finding that an excellent magnetic recording medium can be obtained.

That is, the present invention provides a magnetic recording medium in which an undercoat layer is provided between a non-magnetic support and a magnetic layer, wherein the undercoat layer comprises the following components (1), (2) and (3): Or (1),
The present invention relates to a magnetic recording medium containing the components (2), (3) and (4).

(1) One or two or more resins selected from the group consisting of a polyester resin having a hydroxyl group and a polyurethane resin having a hydroxyl group (2) Polyisocyanate compound (3) Nitrified cotton (4) Organometallic compound and tertiary One or more compounds selected from the group consisting of amine compounds The polyester resin and polyurethane resin used in the present invention are not particularly limited as long as they have a hydroxyl group at the terminal or branched chain of the molecule, and for example, in the case of commercially available polyester resins Byron 103, Byron 200, Byron 200, Byron 280, Byron 290, Byron 300, Byron 500, Unitika Ltd. Unitika Elitel UE-3200, Unitika Elitel UE-3201, Unitika Elitel UE-3300 Therefore, Unitika Elitel UE-3400 can be used.

Further, as a commercially available polyurethane resin, Nippon Polyurethane Industry Co., Ltd.'s Nippon Run 5032, Nippon Run 5033, Nippon Run 2301 and the like can be used.

The polyisocyanate compound used in the present invention is a compound having two or three or more isocyanate groups in one molecule, which may be aromatic, aliphatic, or cycloaliphatic, and is a commercially available product. For example, Nippon Polyurethane Industry Co., Ltd. Coronate L, Coronate HL, Coronate EH, Sumitomo Bayer Urethane Co., Ltd. Sumidule L, Sumidule IL, Desmodur HL, Sumidule N, Sumidule H
T, Sumidule W and the like.

In the present invention, the total amount of the polyester resin or polyurethane resin having a hydroxyl group or a mixture thereof is 10
It is preferably 0 part by weight, and the polyisocyanate compound is preferably used in an amount of 2 to 40 parts by weight. If the amount of the polyisocyanate compound is less than 2 parts by weight, the crosslinking reaction is not sufficient, and if it exceeds 40 parts by weight, it takes a long time until the reaction of the isocyanate group of the polyisocyanate compound is completed, which is disadvantageous. is there. Further, when the unreacted polyisocyanate compound remains, the blocking property of the undercoat layer becomes high, which causes troubles such as sticking to the roll during the process of applying the magnetic coating material.

The nitrification cotton used in the present invention is called industrial nitrocellulose according to JIS K6703, and has a nitrogen content of 10.7-1.
2.2%. Among them, those with a year of 2 to 1/64 second are preferable. Examples of commercially available products are Cellnova BTH1 / 2, Cellnova HIG1 / 16, Cellnova LIG1 / 4, Cellline FM-200, Cellline, manufactured by Daicel Chemical Industries, Ltd., manufactured by Asahi Kasei Corporation.
FM-400, cell line FM-1600, etc. can be mentioned.
This nitrified cotton is used in a total amount of 10% of polyester resin or polyurethane resin having hydroxyl group or mixture thereof.
5 to 50 parts by weight is preferable with respect to 0 parts by weight. If the amount of nitrified cotton used is less than the above range, the swelling or solubility by the solvent is too large, and if it exceeds the above range, the adhesiveness to the base film decreases, which is not preferable.

Examples of the organometallic compound used in the present invention include trisacetylastonatoiron (III) [Fe (C ₅ H
₇ O ₂ ) ₃ ], trisacetylacetonatomanganese (III)
[Mn (C ₅ H ₇ O ₂ ) ₃ ], dibutyltin dioctate, dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, tin octenoate, tin oleate, lead naphthenate, lead oleate, tetraisopropyl titanate, Tetra n-butyl titanate etc. are mentioned.

Further, as the tertiary amine compound used in the present invention,
For example triethylenediamine, triethylamine, Etc.

In the present invention, when using one or two or more compounds selected from the group consisting of the above-mentioned organometallic acid compounds and tertiary amine compounds, the amount used is preferably 0.001 to 8 parts by weight. If it exceeds 8 parts by weight, adverse effects such as blooming on the surface of the undercoat layer occur, and if it is less than 0.001 parts by weight, the effect is insufficient.

In the present invention, the undercoat layer is a gravure undercoat solution prepared by dissolving each of the components (1) to (3) or (1) to (4) in an organic solvent such as acetone, methyl ethyl ketone, cyclohexanone, or ethyl acetate. Coating method, reverse coating method,
It is formed by coating on a non-magnetic support by another method and drying it. An inorganic pigment such as carbon black or titanium oxide may be added to the undercoating liquid for the purpose of preventing electrification or improving light-shielding properties.

The components of the magnetic coating material forming the magnetic layer of the magnetic recording medium of the present invention are not particularly limited, and those normally used may be used as they are. For example, as the magnetic powder, γ-iron oxide, γ-iron oxide containing Co, reduced iron powder, and ferromagnetic powder such as alloy powder of iron / cobalt / nickel can be used. Further, as the binder, polyvinyl chloride, vinyl chloride vinyl acetate copolymer and its partially saponified product, polyvinyl butyral, phenoxy resin, epoxy resin, polyester resin, polyacrylonitrile, polyurethane, polyacrylic acid ester, polymethacrylic acid ester Polyvinylidene chloride, cellulose acetate butyrate, nitrified cotton, and other synthetic or semi-synthetic polymer compounds may be used alone or in admixture of two or more. Also, if necessary, plasticizers such as dibutyl phthalate and dioctyl phthalate, curing agents such as polyisocyanate compounds, α-iron oxide, aluminum oxide, abrasives such as chromium oxide, fatty acid esters,
Lubricants such as fatty acids, antistatic agents such as carbon black and quaternary ammonium salts, and dispersants such as lecithin and alkyl phosphates may be added.

As the non-magnetic support used in the present invention, a polyethylene terephthalate film is preferable.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 80 parts by weight of Byron 200 (polyester resin manufactured by Toyobo Co., Ltd.) Coronate L 18 (polyisocyanate compound manufactured by Nippon Polyurethane Industry Co., Ltd.) Cellline FM-200 20 (nitrified cotton manufactured by Daicel Chemical Industries, Ltd.) ) Methyl ethyl ketone 700 Cyclohexanone 200 A solution having the above mixing ratio was applied on a polyethylene terephthalate base film having a thickness of 75 μm so that the dry film thickness was 0.5 μm, and dried to form an undercoat layer. on the other hand,
After thoroughly kneading and dispersing a mixture having the following composition in a ball mill,
A magnetic paint was prepared by mixing 10 parts by weight of Coronate L as a polyisocyanate compound. The prepared magnetic coating is applied on both surfaces of the above-mentioned undercoat layer so that the dry film thickness will be 1.0 μm, dried, calendered at 70 ° C and linear pressure of 250 kg / cm, and postcured at 50 ° C for 2 days. Then, it was punched out into a 5.25-inch disk to make a magnetic disk. The produced magnetic disk was surface-treated with a polishing tape and loaded into a jacket for evaluation of the magnetic disk.

(Magnetic coating composition) Co-containing γ-iron oxide powder 100 parts by weight Lecithin 2 S-REC A 20 (Vinyl chloride / vinyl acetate / vinyl alcohol copolymer manufactured by Sekisui Chemical Co., Ltd.) Nipporan 2304 20 (Nippon Polyurethane Industry Co., Ltd.) Polyurethane resin manufactured by Condak Tex 975 4 (carbon black manufactured by Colombian Carbon Co., Ltd.) α-iron oxide 10 butyl stearate 5 methyl ethyl ketone 100 toluene 100 cyclohexanone 100 Example 2 Condak Tex 975 30 parts by weight Emulgen 910 1 (Kao) Nonionic surfactant manufactured by Byron Co., Ltd. Byron 200 40 Nipporan 2301 30 (Polyurethane resin manufactured by Nippon Polyurethane Industry Co., Ltd.) Coronate EH 10 (Polyisocyanate compound manufactured by Nippon Polyurethane Industry Co., Ltd.) Cellline FM-400 30 ( Daicel Chemical Industries Ltd. nitrification cotton) Methyl ethyl Tons 1100 Cyclohexanone 600 The above mixture was kneaded and dispersed in a ball mill to make a magnetic disk except that the undercoating liquid in the same manner as in Example 1.

Example 3 Nipporan 2301 100 parts by weight Sumidule W 30 (polyisocyanate compound manufactured by Sumitomo Bayer Urethane Co., Ltd.) Cernova BTH1 / 2 10 (nitrified cotton manufactured by Asahi Kasei Corporation) Methyl ethyl ketone 600 Cyclohexanone 300 The above mixed liquid is a base coating solution. A magnetic disk was manufactured in the same manner as in Example 1 except that the above was adopted.

Example 4 Unitika Elitel UE-3200 90 parts by weight (polyester resin manufactured by Unitika) Sumidule IL5 (polyisocyanate compound manufactured by Sumitomo Bayer Urethane Co., Ltd.) Cellline FM-200 10 Trisacetylacetonato iron ( III) 0.05 Methyl ethyl ketone 700 Cyclohexanone 100 Methyl isobutyl ketone 200 A magnetic disk was prepared in exactly the same manner as in Example 1 except that the above mixed solution was used as the undercoating solution.

Example 5 A magnetic disk was prepared in the same manner as in Example 4 except that 0.5 part by weight of dibutyltin dilaurate was used instead of 0.05 part by weight of iron (III) trisacetylacetonato.

Example 6 A magnetic disk was prepared in the same manner as in Example 4 except that 1 part by weight of triethylenediamine was used instead of 0.05 part by weight of iron (III) trisacetylacetonato.

Comparative Example 1 100 parts by weight of Byron 200 Coronate L 15 methylethylketone 600 cyclohexanone 300 A magnetic disk was prepared in the same manner as in Example 1 except that the above mixture was used as the undercoating liquid.

Comparative Example 2 Condak Tex 975 30 parts by weight Emulgen 910 1 Byron 200 100 Nipolan 2301 100 Coronate EH 10 Triethylenediamine 1 Methyl ethyl ketone 900 Cyclohexanone 500 A magnetic disk was prepared in the same manner as in Example 2 except that the above mixture was used as the undercoating liquid. It was

Comparative Example 3 Nipolan 2301 100 parts by weight Sumidule W 20 Dibutyltin dilaurate 0.2 Methyl ethyl ketone 600 Cyclohexanone 300 A magnetic disk was prepared in the same manner as in Example 3 except that the above mixture was used as the undercoating liquid.

Comparative Example 4 Nipporan 2301 100 parts by weight Trisacetylacetonato iron (III) 0.2 parts by weight Methyl ethyl ketone 600 Cyclohexanone 300 A magnetic disk was prepared in the same manner as in Example 3 except that the above mixed solution was used as the undercoating solution.

Comparative Example 5 A magnetic disk was produced in exactly the same manner as in Example 1 except that the above mixture was used as the undercoating liquid.

Comparative Example 6 A magnetic disk was produced in exactly the same manner as in Example 1 except that the above mixture was used as the undercoating liquid.

Comparative Example 7 A magnetic disk was produced in exactly the same manner as in Example 1 except that the above mixture was used as the undercoating liquid.

Comparative Example 8 A magnetic disk was produced in exactly the same manner as in Example 1 except that the above mixture was used as the undercoating liquid.

Using commercially available floppy disk drives for the magnetic disks prepared in Examples 1 to 6 and Comparative Examples 1 to 8,
The output voltage and output fluctuation at 125 KHz were measured. Here, the output fluctuation is represented by the following equation.

Here, A: About 20 including the maximum output voltage in one track.
00 Flux reversal average output voltage B: Approximately 2000 flux reversal average output voltage including minimum output voltage in one track of the track. Table 1 shows magnetic disks of Examples 1 to 6 and Comparative Examples 1 to 8.
The results of the output voltage at 125 KHz (reference is taken as Comparative Example 1) and the output fluctuation are shown. Since the magnetic recording medium of the present invention has a rapid improvement in the solvent resistance of the undercoat layer and the undercoat layer is provided. It can be seen that the output voltage is excellent and there is no increase in output fluctuation.

Claims (2)

[Claims] 1. A magnetic recording medium having an undercoat layer provided between a non-magnetic support and a magnetic layer, wherein the undercoat layer has the following components: (1) a polyester resin having a hydroxyl group and a hydroxyl group. A magnetic recording medium comprising one or more resins selected from the group consisting of polyurethane resins, (2) a polyisocyanate compound, and (3) nitrification cotton. 2. A magnetic recording medium having an undercoat layer provided between a non-magnetic support and a magnetic layer, wherein the undercoat layer has the following components: (1) a polyester resin having a hydroxyl group and a hydroxyl group. One or more resins selected from the group consisting of polyurethane resins, (2) polyisocyanate compounds, (3) nitrification cotton, and (4) selected from the group consisting of organometallic compounds and tertiary amine compounds. A magnetic recording medium containing one or more compounds.