JPS6059524A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording medium having excellent durability by using an electron ray curable binder consisting of specific branched polyurethane, monomer or oligomer having >=3 acrylic groups in one molecule and specific vinyl chloride polymer for forming a magnetic layer. CONSTITUTION:A magnetic layer formed by dispersing magnetic powder into an electron ray curable binder contg. the three components; branched polyurethane of 10,000-50,000 number average mol.wt. contg. at least straight chain polyester diol having about 500-3,000mol.wt. and polyester triol or ether triol having about 400-3,000 average mol.wt. and diisocyanate compd. (component 1), a monomer or oligomer having >=3 acrylic groups in one molecule (component 2) and a copolymer consisting of vinyl chloride, vinyl acetate, OH group-contg. vinyl monomer, etc. having 10,000-50,000 number average mol.wt. is formed on a base. The magnetic recording medium having good adhesion between the base and the magnetic layer and having excellent durability is thus obtd.

Description

[Detailed description of the invention] Technical field The present invention relates to magnetic recording media, and more particularly.

The present invention relates to a magnetic recording medium using a specific electron beam curable resin as an inder in a magnetic layer.

Prior Art Magnetic recording media, represented by magnetic tapes, floppy disks, etc., mainly contain magnetic particles (for example, γ-F 101) and an electron beam curable binder on a non-magnetic support such as a plastic film. It is known that a material is provided with an a-type layer. This type of magnetic recording medium is produced by applying a V&-type paint 't' containing the above binder onto a support, and then irradiating the surface with an electron beam to cure the paint film.

The manufacturing method of magnetic recording media that uses such an electron beam curable binder to form the magnetic layer has advantages such as preventing the solid content in the magnetic paint from coagulating, improving the pot life, simplifying the manufacturing process, and saving energy. Generally considered to be advantageous.

However, conventional electron beam curable magnetic recording media manufactured in this manner have the characteristics required for the magnetic layer, especially abrasion resistance, dispersibility and adhesion of magnetic powder to the binder, support and magnetic layer. Adhesion is not sufficient. Therefore, the actual situation is that a product satisfying the durability obtained as a result of combining these factors has not been obtained.

Purpose An object of the present invention is to eliminate the above-mentioned drawbacks of conventional electron beam curable magnetic recording media and to provide a magnetic recording medium with excellent durability.

Structure The present invention provides a magnetic recording medium in which a magnetic layer containing magnetic powder and a binder as main components is provided on a non-magnetic support. The inder consists of the following ■~■ and is hardened by irradiation with electron beams.'t'1
This invention relates to a magnetic recording medium.

■ At least molecular weight of about 500 to aoo.

linear I-lyester diol with an average molecular weight of 400-.
3,000 polyester triol and/or IT polyether triol and a diisocyanate compound with a number average molecular weight of 10,000 to 60,000 minutes/9 urethane ■ A monomer having acrylic groups or more in one molecule and/ Or oligomer ■ Nyl chloride polymer with a number average molecular weight of 10,000 to 10,000 S. The molecular weight of ■ is about 500 to 30,000. Linear polyester diols include 7-talic acid, isophthalic acid, and terephthalic acid.
Acids, maleic acid, maleic acid derivatives, succinic acid, saturated polybasic acids such as adipic acid and ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1
．． Examples of polyester triols and/or polyether triols having an average molecular weight of about 400 to 3,000 include those obtained by condensation with dihydric alcohols such as 3-butanediol and 1,4-butanediol. Ace YT-651, YT-650,
YTIOI (polyester triols manufactured by Jiryuka Kogyo Co., Ltd., etc., San-X TP-400, GL-ill O
0G.

Examples include polyether triols such as GP-3000 (manufactured by Sanyo Chemical Industries, Ltd.), and examples of diincyanate compounds include tolylene diisocyanate, isophorone diincyanate, hexamethylene diisocyanate, and methylene bis(4-phenyl isocyanate). etc.

In addition to these, 2-hydroxyethyl (
meth)acrylate, 2-hydroxyzorobyl(meth)
It is possible to add monohydric alcohols such as acrylates, dihydric alcohols such as 1,4-butanediol, etc.

5- ■ As a monomer having three or more acrylic groups in one molecule, (CH! = CHCOOCHI +s CR (in the formula,
R is -C! H,CHs, -CH,OH.

-CH, CH, 0H1-CHCH. )OH can be used. Further, as the oligomer, an oligoester acrylate (trifunctional or higher) represented by (wherein ^ represents acrylic acid, X represents polyvalent aluminum, and 7 companies polybasic acid) can be used. As this oligo i-, M-7100, M-8080, M-80 manufactured by Toagosei Chemical Industry Co., Ltd.
110, M-8100, etc.

As the vinyl chloride polymer having a number average molecular weight of 10,000 to 10,000, a copolymer of vinyl chloride, vinyl acetate, and -oitityl monomer is used. -〇H group-containing vinyl monomer and J vinyl alcohol, vinyl carboxylic acid, etc. :6 copolymer) and YMCA (vinyl chloride;
Vinyl acetate = dibasic FII 81!17:20 copolymer) and the like.

The mixing ratio of ■, ■, and ■ in the above binder is 1
．． ? In 100 parts by weight of Inder, 40 to 90 parts by weight of polyurethane, 5 to 301 parts of monomer and/or oligomer, and 5 to 30 parts of vinyl chloride polymer.
It is desirable that the amount is 1 t parts.

The above electron beam curable binder has a magnetic powder of 100%
Usually, about 10 to 70 parts by weight are used.

Magnetic powders include γ-Few Oa and cO-containing r-Fe.
103, F@@04, Cr0g, or F., Co.

Hayabusa magnetic metal powder such as N1 or F.-Co.

Fa-N1. Fe-Co-Nl, CO-NI
Examples include magnetic alloy powder such as MnB. These magnetic powder valinates; fatty acid amides, silane-based, titanium-based or aluminum-based coupling agents: or SiO! ,
It may also be surface-treated with a pigment such as Ti01.

In addition to the above-mentioned materials, additives known in this field, such as dispersants, antistatic agents, lubricants, and abrasives, can be used in the magnetic layer.

Dispersants include caprylic acid, capric acid, lauric acid,
Fatty acids having 12 to 18 carbon atoms such as stearic acid (n,
C0OH, R1 is an alkyl or alkyl group having 11 to 17 carbon atoms); an alkali metal of the above fatty acid (Li,
Na.

K, etc.) or alkaline earth metals (Mg, Ca.

(Bi, etc.): A fluorine-containing compound of the above-mentioned fatty acid ester: An amide of the above-mentioned fatty acid, d-realkylene oxide alkyl phosphate, lecithin, etc. are used. These dispersants are added in an amount of 2 to 5 parts by weight per 100 weight parts of the magnetic particles.

Carbon black, graphite,
A conductive fine powder such as carbon fiber graft polymer is used. When these antistatic agents are added, they are added in an amount of 3 to 10 parts by weight per 100 parts by weight of magnetic powder.

In addition, silicone oil, graphite,
Molybdenum disulfide, fatty acid esters consisting of a basic fatty acid having 12 to 16 carbon atoms and a partial alcohol having 3 to 12 carbon atoms, and the like are used. When these lubricants are added, the amount is 3 to 10 parts by weight per 100 parts by weight of the magnetic powder.

As the abrasive, molten aluminum, silicon carbide, chromium oxide, corundum, etc. can be added.

Examples of the non-magnetic support used in the present invention include polyesters such as polyethylene terephthalate, polyethylene,
Polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate, -liquor 5lZ4-), film sheets such as polyvinyl chloride, jellyoid, paper, synthetic paper, alumina plastic, etc. It is possible. Further, the surface of these supports may be treated with corona discharge, radiation, ultraviolet light, etc., or may be precoated with a suitable resin.

In particular, when using a polyester film, it is preferable to pre-soot it with a mixed composition of a thermoplastic polyester resin and a polyisocyanate compound and heat-treat it before use.

To make the magnetic recording medium of the present invention, the above materials are dispersed in a solvent such as acetone, toluene, methyl ethyl ketone, or cyclohexanone to form a magnetic paint, and this is applied as a final film on a non-magnetic support such as a plastic film or synthetic paper. Thickness is 2~
Doctor blade, wire) e-
It may be applied by a coating means such as, etc., and after heating and drying, the surface of the coating film may be irradiated with an electron beam to be cured.

-l〇 - Electron beam irradiation is carried out using an electron beam accelerator with an accelerating voltage of ioo to 750 KV, preferably 150 to 200 KV, so that the absorbed dose is 2 to 15 Mrad. in this case,
Since the presence of oxygen inhibits the curing reaction, it is desirable to remove it as much as possible.

Effects The present invention has excellent durability by using the above-mentioned specific electron beam curable binder. Mainly, the above-mentioned polyurethane contributes to improving elasticity, the above-mentioned monomer and/or oligomer contributes to improving cohesive force and adhesiveness, and the above-mentioned vinyl chloride polymer contributes to improving compatibility and adhesiveness. .

Examples of synthesizing polyurethanes according to the present invention will be shown below, and the effects of the present invention will be specifically illustrated by examples using these polyurethanes.

All parts are parts by weight.

Synthetic Leather Example 1 After reacting 12, Of 11 in methyl ethyl ketone solvent for 3 hours, di-n-decyltin dilaurate 2 cups toluene solution "Y"
5 dlfI: was added, and the reaction was further continued for 10 hours. The polyurethane produced had a number average molecular weight of about 43,000.

Synthesis Example 2 San-X TP-4008,3t Adeka New Ace Y4-310 10022.4-)
A polyurethane having a number average molecular weight of about 25,000 was synthesized in exactly the same manner as in Synthesis Example 1, except that lylene diisocyaner) 8.7# was used.

Example 1 A mixture consisting of CO-rF@lo, 100 parts lauric acid, 4 parts silicone oil, 6 parts, and 3 parts of abrasive ($0 for A) was dispersed for 15 hours in a V&-R slurry. Next, 7 parts of VAGH (manufactured by Union Carbide) and 23 parts of the polyurethane of Synthesis Example 1 (CH* -CHCooCHs +, CCH Tomi OH5) were added to this dispersion.
7 parts and 50 parts of 1flS force-I black dispersion liquid were added and dispersed in an I-rule for about 15 hours to obtain a magnetic layer forming liquid.

This viscous dispersion (magnetic layer forming liquid) was spread over one kilometer of ethylene tele-7 tallate film (thickness II to 100j11) using a t-2-3 doctor blade.
~1. After drying at IO °C to remove the solvent, the accelerating voltage 8
o.

KV, f-mul [flow 10~1! imA ) to 8 I(
Electron beam irradiation was performed using an electron beam accelerator (curtain type) at an absorbed dose in the range of 3 to 19 Mrad,
/? A magnetic recording medium was prepared by under-hardening to form a magnetic layer with a thickness of about 6#. CCHloHK fee, tte(cH,
A magnetic brass medium was prepared in the same manner as in Example 1, except that 8 parts of mCH000CHa+g COHe CHs was used.

14- Example 3 20 parts of the polyurethane of Synthesis Example 1, (CH yo; CHCOO
A magnetic recording medium was produced in the same manner as in Example 1, except that 8 parts of M80BQ (manufactured by Toagosei Kagaku Kogyo Co., Ltd.) was used in place of CH, -3-, CCH TomiOH.

Comparative example 1 (CHI −CHCOOCHI +, (ICH,OH
A magnetic recording medium was produced in the same manner as in Example 1, except that 13 parts of ICH, 錛CHCOOCH, CH, and OH were used instead.

Comparative Example 2 25 parts by weight of the polyurethane of Synthesis Example 2 and (CHI-C
HCOOCHg +* ICHI instead of CC horse CH,
A magnetic recording medium was produced in the same manner as in Example 2 except that -CHCOOC horse CHsB part was used and VAGHt was omitted.Comparative example 3 Diene I-leum 19-4 was used in place of the polyurethane in Synthesis example 1.
Except that 23 parts of 827 (urethane acrylate manufactured by 7Liman Chemical Co.) was used.

A magnetic recording medium was produced in the same manner as in Example 1.

The magnetic recording media of the above Examples and Comparative Examples were shaped into disks and held in a commercially available Teno 1 set scratch tester (manufactured by Toyo Seiki Co., Ltd.) to relatively evaluate the degree of wear on each magnetic recording medium. Durability was evaluated with a low rating of t○ and a high rating of YX. The results were as shown in the table belowQ

Claims (1)

[Scope of Claims] 1. A magnetic recording medium in which a magnetic layer containing magnetic powder and a binder as main components is provided on a non-magnetic support, wherein the binder consists of the following (1) to (3), and the magnetic layer is irradiated with an electron beam. A magnetic recording medium characterized by being hardened by. ■ At least a linear polyester diol with a molecular weight of about soo~300°, a polyester triol and/or a polyether triol with an average molecular weight of about 400~3000, a diisocyanate compound, and a number average molecular weight of 10,000~50,000. Branched polyurethane■ Monomer and/or oligomer having three or more acrylic fundamental sounds in one molecule■ Chlorinated hydrogen-based polymer with a number average molecular weight of 10,000 to 50,000