JPS59157839A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording medium having good dispersibility of magnetic powder and having an excellent magnetic characteristic, durability, etc. without dislodging by providing a magnetic layer contg. trialkoxysilane contg. amide and carbonyl groups, a binder and magnetic powder. CONSTITUTION:Trialkoxysilane expressed by the formula (R1 is 1-3C alkyl, R2 is 1-3C alkylene, R3 is H, hydrocarbon such as 1-6C alkyl, phenyl, etc.) is dissolved in a solvent such as toluene, and ferromagnetic powder such as Co-contg. gamma-Fe2O3 or the like is dispersed and thereafter the magnetic powder is taken out and surface is cleaned and dried, by which the magnetic powder which is coated by trialkoxysilane on said is obtd. Diketene is blown into such magnetic powder dispersed in a binder resin soln. and after mixing and dispersing, a low mol.wt. isocyanate compd. is further added thereto to prepare a magnetic coating. The coating is applied on a base and is cured, by which a magnetic recording medium provided with uniform dispersibility by the trialkoxysilane having the amide group and the carbonyl group and having excellent wear resistance, a magnetic characteristic, etc. is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and its purpose is to provide a magnetic recording medium that has good dispersibility of magnetic powder, excellent magnetic properties, and is highly durable. .

Magnetic recording media are usually made by applying a magnetic paint consisting of magnetic powder, a binder component, an organic solvent, and other necessary components onto a substrate such as a polyester film, and drying the coating.
The magnetic powder is required to have good dispersibility, good magnetic properties, and excellent durability.

Therefore, attempts have been made to improve the dispersibility of magnetic powder by treating it with various dispersants, etc. to improve its magnetic properties, and also to improve its wear resistance, but these efforts are still not fully satisfactory. I haven't gotten what I could have.

In view of the current situation, the inventors have carried out various secret strategies, and as a result, they have incorporated a trialkoxysilane containing an amine group into the magnetic paint, and injected or added diketene into the magnetic paint. When a trialkoxysilane containing an amide group and a carbonyl group produced by reacting with an alkoxysilane is contained in the magnetic layer, the dispersibility of the magnetic powder is sufficiently improved and the magnetic properties are further improved. Furthermore, it has been discovered that the use of a low molecular weight isocyanate compound as a binder component further improves the carving resistance of the magnetic layer, leading to the present invention.

In this invention, the trialkoxysilane containing an amide group and a carbonyl group contained in the magnetic layer is produced by reacting a trialkoxysilane containing an amino group with diketene in a magnetic paint, and is used here. The mtrialkoxysilane containing an amine group has the general formula 4% (wherein R1 is an alkyl group having 1 to 3 carbon atoms, R2 is an alkylene group having 1 to 3 carbon atoms, and R is H or a carbon number 1 to 6) are preferably used, and specific examples include those represented by the following structural formulas.

(C2H50)3St-0-CH2CH2-NH-C2
H5 (2-N-ethynogeminoethoxy-triethoxysilane) (CR30)3 Si-0-CH2CH2
-NH-C2H5 (2-N-ethylaminoethoxy-trimethoxysilane) (2-N-phenylaminoethoxytriethoxysilane) (2-N-phenylaminoethoxy-trimethoxysilane) (CH30) 3 Si
-0-CH 2Cl-1 2NH 2 (aminoethoxy-trimethoxysilane) This trialkoxysilane containing 7 amino groups of yuzu is a silane coupling, which forms a strong chemical bond between organic and inorganic substances. When it comes into contact with magnetic powder, it strongly reacts with the hydroxyl group in Table 1f11 of the powder particle, breaking the bond between the silicon atom and -(OR1)a, and the silicon atom connects to the surface of the magnetic powder via oxygen. It is strongly bonded to. Therefore, when this trialkoxysilane containing the amino group of yuzu is contained in a magnetic paint, it adheres firmly to the surface of the magnetic powder particles, and when diketene is then added to this magnetic paint, it adheres to the surface of the magnetic powder particles. The strongly adhered trialkoxysilane containing amide 7 groups reacts with diketene to produce trialkoxysilane containing amide groups and carbonyl groups, and a film made of this product is firmly coated on the surface of the magnetic powder particles. As a result, the dispersibility of the magnetic powder is sufficiently improved, and the magnetic properties are further improved. In addition, the affinity between the magnetic powder and the binder resin is improved, and the wear resistance is also improved, and these effects are especially remarkable when cyclohexanone is used as an organic solvent to dissolve the binder resin, further improving magnetic properties and durability. An excellent magnetic recording medium can be obtained.

Furthermore, when a low molecular weight incyanate compound is used as a binder component together with a trialkoxysilane containing an amide group and a carbonyl group produced by reacting a trialkoxysilane containing an amide group with diketene, this The resistance of the alpha layer is due to the fact that the incyanate groups of low molecular weight isocyanate compounds react with hydroxyl groups in resins such as cellulose resins and vinyl chloride-vinyl acetate copolymers used as binder components, resulting in crosslinking. Abrasion resistance is further improved.

Such trialkoxysilanes containing amide 7 groups can be removed by dissolving them in an appropriate solvent, and by this dissolution, the ion
Add this solution to the 7 core paint at the time of application, or immerse the magnetic powder during this melting process, perform surface uf1 treatment on the magnetic powder in advance, and use this magnetic powder. Ek
Contained in magnetic paint by methods such as making magnetic paint into a core,
By blowing or adding diketene in an equimolar amount to the trialkoxysilane containing an amino group into this core coating, a trialkoxysilane containing an amide group and a carbonyl group is produced and contained in the magnetic layer. The content of the thus produced multitrialkoxysilane containing an amide group and a carbonyl group in the pentagonal layer is in the range of 0.05 to 5% with respect to the magnetic powder in the magnetic layer. It is preferable that the content is less than 0.05% by weight, and the desired effect may not be obtained, and if it exceeds 5% by weight, there is a risk of bleed-out.

Examples of the magnetic powder used in this invention include r-F
e 203 powder, Fe50. Powder, Co-containing r-Fe2
In addition to 03 powder, Co-containing Fe 304 powder, and CrO2 powder, various conventionally known magnetic powders such as metal powders such as Fe powder, Co powder, and Fe-Ni powder are widely included.

In addition, as binder resins, conventionally widely used binder resins such as TIF fiber resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, polyurethane type a resin, and low-molecular binder resins (isocyanate compounds) are used. Both are used.

Examples of organic solvents include ketone solvents such as cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone.
Chu: Ester solvents such as Sou Ethyl, Nishi IE iV Shun Dibutyl, etc., benzene, toluene, xylene, etc. (D aromatic M hydrocarbon solvents, alcohol solvents such as isopropyl alcohol, acid amide solvents such as dimethylformamide, dimethyl sulfoxide, etc.) Solvents suitable for dissolving the trialkoxysilane and binder resin used, such as sulfoxide solvents, tetrahydrofuran, ether solvents such as dioxane, can be used alone or in combination of two or more without particular restrictions, Cyclohexanone is particularly preferably used.

In addition,#? The coating contains various oil additives commonly used in the coating, such as dispersants, detergents, abrasives, and antistatic agents.
(You may add or use as appropriate.)

Next, one embodiment of the present invention will be described.

Example 1 10 weight parts of trialkoxysilane represented by the structural formula % are dissolved in 990 weight parts of toluene, and Co-containing -Fe
200 parts by weight of 203 magnetic powder (washed after dispersion treatment,
After drying, 0.2'NcM% amyl/rod on the surface of the powder particles:
A magnetic powder containing trialkoxysilane was obtained. Using this magnetic powder, Co-containing r-Fe20
J powder 80 parts (Trialkoxysilane t
ff b f3t 0.2%) Nitrocellulose H1 (Nitrocellulose manufactured by Chuka 10μ Seisha) Bandex T-525010// (Manufactured by Dainippon Ink Co., Ltd., Urethane Nidistomer) Carbon blank 0.5〃Steariner-n -Butyl 8 Myristine 4 Cyclohexanone 100 Toluene
A mixture having a composition of 100% was mixed and dispersed in a ball mill for 72 hours, and then 45 parts by weight of diketene was added by blowing into the mixture, and the mixture was mixed and dispersed for 5 hours.
Furthermore, a solution of 5 parts of a trifunctional low molecular weight isocyanate compound manufactured by Bayer AG dissolved in a mixed solvent of 5 parts of hexanone and 5 parts of toluene was added and the mixture was further mixed for 1 hour. A magnetic paint was prepared by dispersing it.

This magnetic paint was applied onto a polyester base film with a thickness of 11 μm to a dry thickness of about 4 μm, dried, and after surface treatment, cut into a predetermined width to produce a magnetic tape.

Example 2 A magnetic tape was produced in the same manner as in Example 1, except that desmodule L was omitted and the amount of nitrocellulose H1 used was changed from 10 parts by weight to 15 parts by weight in the preparation of the magnetic paint in Example 1. Ta.

Example 3 In the preparation of the magnetic paint in Example 1, VAGH (U.S.) was used instead of nitrocellulose H1.

C, c company? Example 1 except that the same amount of m-vinyl acetate-vinyl alcohol copolymer) was used and the same amount of methyl isobutyl ketone was used in place of cyclohexanone.
I made magnetic tape in the same way.

Example 4 In the preparation of the magnetic paint in Example 3, Desmodur L was omitted and the amount of VAGH used was changed from 10 parts by weight to 15 parts by weight.
A magnetic tape was produced in the same manner as in Example 3 except that the parts by weight were changed.

Example 5 In the preparation of the magnetic coating material in Example 1, a Co-containing resin surface-treated with a trialkoxysilane containing 7 amino groups was used.
r-Fe, untreated C in place of 80 parts by weight of 03 magnetic powder
80 parts by weight of o-containing -F e 203 hri powder was used, and 5 parts by weight of trialkoxysilane expressed by the same formula 4 to q as used in Example 1 were newly added to the magnetic paint composition. A magnetic tape was produced in the same manner as in Example 1 except for the following.

Comparative Example A magnetic tape was prepared in the same manner as in Example 5, except that the trialkoxysilane containing amide 7 groups was omitted and the blowing addition of diketene was omitted in the preparation of the magnetic paint in Example 5.

Regarding the magnetic tapes obtained in each example and comparative example,
To measure the square shape (Br/Bm), and to check durability and gR, each 30 m long magnetic tape was installed in a cartridge, and the tape was run continuously for one hour in a testing machine to ensure that the magnetic powder in the cartridge fell off. The amount was observed. The amount of falling off was visually observed and evaluated as ◯ when no falling off, △ when slight falling off was observed, and × when a large amount of falling off was observed.

The table below shows the results.

As is clear from the table above, the magnetic tapes obtained according to the present invention (Examples 1 to 5) all have higher squareness than the conventional magnetic tapes (Comparative Examples), and the magnetic powder is less likely to fall off. The amount of magnetic particles is very small, not observed at all, or only a small amount is observed. Therefore, the magnetic recording medium obtained by the present invention has good dispersibility of magnetic powder, excellent magnetic properties, and durability. I can see that you are immersed in it.

Claims (1)

[Claims] 1. A magnetic recording medium having a magnetic layer comprising a magnetic powder, a trialkoxysilane containing an amide group and a carbonyl group, and a binder component. 2. A low molecular weight isocyanate compound as the binder component. The magnetic recording medium 3 according to claim 1, which contains magnetic powder, is contained in the magnetic layer in a state where the magnetic powder is coated with trialkoxysilane containing an amide group and a carbonyl group. The magnetic recording medium described in item 1 of the scope of