JPS59218630A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve dispersibility of magnetic powder and durability of a coated film layer by incorporating the magnetic powder coated with the resultant product of reaction between a specific amide compd. and a specific isocyanate compc. into said film. CONSTITUTION:The resultant product of reaction between an amide compd. having an amide bond and having at least one of a hydroxyl group or amino group and a compd. selected from a polyisocyanate group having 2 or >=3 isocyanate groups and an isocyanate compd. having a hydrolyzable alkoxysilane and 1 or >=2 isocyanate groups is used. The amide compd. is obtainable from an acid, acid halide or acid anhydride selected from a fatty acid or acid halide, monobasic or polybasic oxy acid or acid halide thereof, alkenyl or alkyl succinic acid, acid halide or the anhydride anhydride thereof and an amine compd. selected from alkylene diamine, the polyalkylane polyamine expresses by the formula, alkyl or alkenyl amine and alkanol amine.

Description

[Detailed description of the invention] The present invention relates to modified magnetic recording media.

More specifically, the present invention relates to a magnetic recording medium that has excellent magnetic properties and durability and is manufactured using a magnetic paint that has improved dispersibility of magnetic powder and improved adhesion between the magnetic powder and a binder.

Magnetic powder in magnetic recording media such as magnetic tapes and magnetic disks is required to have a high degree of dispersibility.

Magnetic recording media are generally manufactured by kneading magnetic powder, binder, various additives, and solvents, then uniformly applying a magnetic paint onto a plastic film or sheet substrate, drying it, and then finishing the magnetic layer with a mirror finish. However, unless the magnetic powder in the magnetic paint is sufficiently dispersed and peptized to remove aggregated particles, it is not possible to create a uniform and smooth magnetic layer with a high packing density.

Non-uniformity in the magnetic layer due to agglomerated particles of magnetic powder has a serious adverse effect on the electromagnetic conversion characteristics and magnetic properties of the magnetic tape.

In other words, it causes a decrease in output, an increase in noise, and a dropout.

Also, if the adhesive force between the magnetic powder and the binder is weak,
When a magnetic recording medium and a recording head or a reproducing head slide, magnetic powder tends to peel off from the magnetic coating layer (so-called "one powder drop"), which roughens the coating surface and reduces the durability of the magnetic recording medium. sexuality is impaired. Magnetic recording media may be exposed to high temperature or high humidity environments when used in recording and reproducing devices or during storage, but even under such conditions, It is desired that there is little decrease in adhesive strength and that deterioration in strength and physical properties is as small as possible.

In reality, conventional magnetic recording media have been put into practical use with insufficient durability.

As described above, the dispersibility of the magnetic powder in the magnetic paint and the adhesion with the binder are very important in improving the performance of the magnetic recording medium.

Improvements in the dispersibility of magnetic powder have been studied from various viewpoints, and it has been proposed to improve the dispersibility by adding a suitable surfactant to the magnetic paint formulation. Examples of such surfactants include those using an alkyl igudacylin compound (Japanese Patent Application Laid-Open No. 54-32304), and those using an alkylpolyoxyethylene phosphate neutralized with an alkyladine (Japanese Patent Application Laid-Open No. 53-78810). , using a long-chain alkyl phosphate ester (JP-A-54-147507.
As shown in Japanese Patent Application No. 53-49629) 5-, amines and their derivatives, phosphoric acid esters, polyoxyethylene phosphoric esters, etc. are often used. In addition, there is a proposal that dispersibility is improved by surface-treating magnetic powder and then turning it into a paint, using an alkyl polyoxyethylene phosphate ester (+?? 1986-94308, 1983-49769). , which treats metal powder with a titanium coupling agent to measure dispersion stability and at the same time prevent the deterioration of the magnetic coating film over time (Japanese Patent Application Laid-Open No. 5F1-
88471). One way to improve the durability of magnetic coatings by improving the adhesion between magnetic powder and binder is to use a silane coupling agent with a functional group reactive with the binder (Japanese Patent Laid-Open Publication No. 54-7310),
The reaction products of aminofunctional silane coupling agents, isocyanate compounds, and epoxy compounds (Japanese Patent Application Laid-open No. 143333/1983), double bonds in the binder and unsaturated bonds capable of radical polymerization are A method for treating magnetic powder with a titanium coupling agent containing at least 4
A compound that uses as a binder a compound having radiation-sensitive acrylic double bonds (Japanese Patent Application Laid-Open No. 57-40744
)and so on. As described above, although much research has been carried out on improving the dispersibility of magnetic powder in magnetic coatings and the durability of magnetic coatings, no satisfactory improvement has yet been reached.

In view of the above-mentioned problems of magnetic recording media, the present inventors, as a result of Eido's research, aimed at obtaining a magnetic recording medium with excellent dispersibility of magnetic powder and durability of the coating layer. Contains magnetic powder coated with a reaction product of a specific isocyanate compound and an adendo compound having a do bond and at least one of a hydroxyl group and an adeno group. We have completed the present invention by discovering that the magnetic recording medium has good dispersibility of magnetic powder, excellent durability of the coating layer, and little deterioration in strength and physical properties even when exposed to high temperature and humidity. That is, the present invention provides an and compound having a molecular weight of 100 or more and having an ado bond in the molecule and having at least one of a hydroxyl group and an adeno group, and the following (1) and (II), ( ■) A polyisocyanate compound with a molecular weight of 100 to 1000 having two or more isocyanate groups in one molecule (■) A hydrolyzable alkoxysilane group and one
Molecule 1t1 having 2 or more incyanato groups
The present invention provides a magnetic recording medium containing magnetic powder coated with a reaction product with one or more inocyanate compounds selected from the group consisting of 40 to 1,500 isocyanate compounds.

Isocyanate compounds belonging to the group consisting of (1) and (n) above according to the present invention include toluene diisocyanate, methylene bisphenylene diisocyanate, hexamethylene diisocyanate, trimethylolpropane 1 mol toluene diisocyanate. Reaction product with 3 mol, OCN-(CHm)s-NHCONH(CHt)
s8i(OCHs)s.

OCN(XCHs÷NHCO-8-(CHs)m-81
(OCH嘗) 1, CH.

etc. can be mentioned.

The and compound according to the present invention has an ad bond in the molecule and has a hydroxyl group or an As long as it is an and compound having a molecular weight of 100 or more and having at least one of the groups, its molecular structure and manufacturing method are not limited, but typical and compounds include the following (1) to (3). group A, A
Group (1) Fatty acids or acid halides having 6 to 22 carbon atoms (2) Monobasic or polybasic ox-9-enoic acids having 2 to 22 carbon atoms, or acid halides thereof (3) Number of carbon meters (t)
o to 26 alkenyl or haalkyl succinic acids, acid halides, or anhydrides thereof; one or more acids, acid halides, or amorphous hydrates; and the following (4) to (7). Group B, Group B (4) Alkylene chain having 2 to 20 carbon atoms (5)
Polyalkylene represented by the general formula R HEN CnHmn (NCnHan) x NH* (wherein, n is an integer of 2 to 10, R is hydrogen or an alkyl group having 1 to 4 carbon atoms, and X is an integer of 1 to 10) Boriaon (6) Alkyl or alkanyl group having 6 to 22 carbon atoms (7) Obtained from one or more and compounds selected from alkanol groups having 2 to 2 carbon atoms, containing a hydroxyl group or an alkyl group. Amide compounds having at least one of the following groups are listed below.

Furthermore, compounds belonging to the above-mentioned group A are illustrated.

(1) As fatty acids having 6 to 22 carbon atoms, lauric acid,
Examples include saturated fatty acids such as balmitic acid, stearic acid, and behenic acid, unsaturated fatty acids such as oleic acid, linoleic acid, and erucic acid, and acid halides obtained from these acids.

(2) Monobasic or polybasic oxyacids having 2 to 2 carbon atoms include glycolic acid, lactic acid, hydroacrylic acid, oxybutyric acid, hydroxystearic acid, hydroxypalmitic acid, hydroxynonacabucanoic acid, ricinoleic acid, ricylic acid, Aliphatic oxyacids such as ricinoelaidic acid, glyceric acid, tartronic acid, malic acid, tartaric acid, citric acid 1, etc., aromatic oxyacids such as salicylic acid, oxybenzoic acid, gallic acid, mandelic acid, trobic acid, etc. acid halides obtained from the acids of

(3) Examples of alkenyl or alkyl succinic acids having to to 26 carbon atoms, acid halides, or their anhydrides include decenyl succinic acid or its anhydride, dodecenyl and succinic acid or its anhydride, and octadecyl succinic acid or its anhydride. Examples include dodecylsuccinic acid or its anhydride, acid halides obtained from these succinic acids, and the like.

Further, amine compounds belonging to the above group B are illustrated below.

(As alkylene diamines with 41 carbons i2 to 20,
Examples include ethylene cyanide, propylene diamine, hexamethylene diamine, octamethylene diamine, dodecylamine, nonamethylene diamine, dodecamethylene diamine, octadecamethylene diamine, and the like.

(5) General formula % Formula % (In the formula, n is an integer of 2 to 10, R is hydrogen or carbon number 1 to
Examples of polyalkylene polyamines represented by the alkyl group of 4 and X represents an integer of 1 to 10 include diethylenetriane, triethylenetetraone, tetraethylenepentamine, dipropylenetriane, tributylenetetramine, and dibutylenetriane. Examples include fon, tributylenetetramine, bis(3-aminoethyl)amino, 1,3-bis(3'-aζnobropylanno)propane, and the like.

(6) As the alkyl or alkenylamine having 6 to 22 carbon atoms, hexylamino, octylamino, decylthymine, dodecylamine, tetradecylamine, hexamethylene di, octadecylamine, undecenylamine,
Oleylamine, etc. can be mentioned.

13- (7) As the alkanolamine having 2 to 20 carbon atoms,
Mention may be made of 2-aminoethanol, 1-aminepentan-5-ol, 2-af/hexane-1-ol, N-(2-oxyethyl)ethylenecyamino, and cape.

From these compounds belonging to group A and compounds belonging to group B,
An amide compound can be easily obtained by a known method.

The magnetic powder according to the present invention includes needle-shaped fine r-F.
Gold M like e嘗Os, Fe5Oa @ crol
l! r-Fa compound, and processed r-Fa such as Co-coated r-Pesos and Co-doped r-Pesos.
mes Iron metal powder, barium ferrite in the form of microplates, and some of its ve atoms are 'ri, CO, Zfl, V
, magnetic powder substituted with one or more types such as Nb, C
Examples include ultrafine powders of metals or alloys such as 0, Fe-C0, and Fe-N1. Among these, iron metal powder is #I
Because of its poor chemical stability, small amounts of XL-) Kel, cobalt, titanium, silicon, aluminum 14-, etc., in the form of metal atoms, salts, and oxides may be added or surface treated to improve this property. You can also use In order to stabilize iron metal powder, a thin oxide film may be formed on the surface in a weakly oxidizing atmosphere, and metal powder treated in this way can also be used.

The size of these magnetic powders is from 1μ to 0.15μ on the long axis.
It is preferable that the minor axis is 0.15μ to 0.015μ.

If the length of the long sleeve is larger than 1 μm, dispersion becomes easier, but recording of short wavelengths becomes disadvantageous and noise increases, which is not preferable. When the long axis is smaller than 0.15μ, even the magnetic recording medium of the present invention cannot be said to have sufficient dispersibility.

In the present invention, the method for obtaining the magnetic powder coated with the reaction product of the amide compound and the isocyanate compound is not particularly limited, and the following methods may be exemplified.

b) A method in which the magnetic powder (1) is first heat-treated with the incyanate compound (11) in an inert organic solvent, and then the amide compound (muscle) is heat-treated.

(1), (11) and (II) in an inert organic solvent.
A method in which D is mixed all at once and heat treated.

C) A method of first reacting the above (11) and (music) in an inert organic solvent, and then adding (1) and heat-treating the magnetic recording medium of the present invention. It can be obtained by adding a binder, a solvent, and if necessary a hardening agent to the powder to make it into a paint, and then applying it to a polyester film, etc. For details, please refer to the examples as well as the method for processing the magnetic powder. explain.

The amount of the isocyanate compounds (1) and (If) used in the present invention is about 0.1 to 7% by weight, preferably 0.3 to 3% by weight, based on the magnetic powder. The amount of the amide compound to be used is such that stoichiometrically, there is no unreacted product, and at least one isocyanate group remains in the polyisocyanate compound. It is preferable that Furthermore, it is needless to say that it is preferable to set reaction conditions such as reaction temperature and reaction time so as to maximize the reaction rate.

Examples of inert solvents that can be used in the treatment of magnetic powder include methyl ethyl ketone, methyl imbutyl ketone, diethyl ketone, Schiff-tetrahexanone, benzene, xylene, and toluene.

The binder used when turning the treated powder into a paint is a resin binder that is soluble in organic solvents, and is used to bind the above magnetic powder onto a substrate and fix the magnetic powder to each other with the necessary strength to form a magnetic layer. It is sufficient that it fulfills its role in as small a quantity as possible, and even those that are concerned about deteriorating the dispersibility of magnetic powder in conventional paints can be used in normal paint-forming methods. Examples of these resin binders are polyurethane,
Polyester, polyvinyl chloride, vinyl chloride vinyl acetate copolymer, polyacrylonitrile, nitrile rubber, epoxy resin, alkyd resin, polyand, polyacrylic acid varnish, polymethacrylate ester, polyvinyl acetate, polyvinyl butyral, chloride Vinylidene, vinylidene chloride copolymer, nitrified cotton, ethyl cellulose, etc. may be used alone, but two or more types are usually used as a mixture. Further, in order to adjust the hardness of the resin, a plasticizer or a hardening agent may be added.

Further, the amount of the binder blended is generally 15 to 60 parts by weight per 100 parts by weight of the magnetic powder. Even if the binder has the highest binding strength, if it is less than 15 parts by weight, the strength of the magnetic coating will be weak and the adhesive strength between the substrate and the magnetic m-film will be insufficient.

If the amount is more than 60 parts by weight, the concentration of magnetic powder in the magnetic coating film becomes small, which is disadvantageous because the reproduction output decreases, and the properties of the coating film may also deteriorate.

It is desirable that the solvent used for forming the coating has a dissolving power for the binder used and a boiling point between 50 tr and 150 C. If the boiling point is too low, the magnetic powder will dry after coating before being oriented in the magnetic field, making this treatment impossible. The binder is selected from the above viewpoints depending on the type of binder, but it goes without saying that it should be selected in consideration of toxicity and environmental issues.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

(Example 1) 4 tube flasks with condensing tubes, major axis diameter 0.35 μm, 1 axis ratio 1
/10 CO deposited r-Fagot 1 B Of, methyl ethyl ketone 400 f, isocyanate compound? The mixture was stirred at 90C for 1 hour. Thereafter, the magnetic powder was washed with dehydrated methyl ethyl ketone. Next, the magnetic powder was mixed with hydrococonium-containing amide compound 2.5F obtained by reaction of 2 moles of ricinoleic acid and 1 mole of diethylene triaine, and methyl ethyl ketone 3.
Add 00g, 80-90? ? The mixture was stirred for 1 hour to obtain treated magnetic powder.

The treated magnetic powder was then washed with a large amount of methyl ethyl ketone. l+1 of the treated magnetic powder, a vinyl chloride-vinyl acetate copolymer (VAGH manufactured by Union Carbide Co., Ltd., USA) and a polyurethane resin (Niraporan 2304 manufactured by Nippon Polyurethane Industries, Ltd.) as a binder.
(weight ratio) of 25% by weight based on the magnetic powder and 1% of methyl ethyl ketone and cyclohexanone as a solvent.
;l (weight ratio) mixture 160? After mixing and kneading in a ball oil for 24 hours, a curing agent (Coronate L from Nippon Polyurethane Industry ■) 12. ! A magnetic paint was obtained by adding 5f and stirring until the system became homogeneous.

Further, this magnetic coating material was applied onto a polyester film using a 30#m applicator, subjected to magnetic field orientation, hot air drying, and then calendered to smooth the coating film to obtain a magnetic recording medium. Next, the magnetic recording medium was measured for the corner ratio, which is a measure of evaluating the dispersibility of the magnetic powder, and the wear loss, which is used to evaluate the durability of the magnetic recording medium. Abrasion loss is when left for 24 hours in an environment with a temperature of 20C and relative humidity of 50C (appropriate temperature and humidity).
, and when left for 24 hours in an environment of temperature 40C, relative humidity 90C (high temperature and high humidity).

Abrasion loss was measured by rubbing a magnetic recording medium with a width of 3 pieces and a length of 50 crn against a TO-1000 emery paper under a constant load for 30 minutes when the temperature was appropriate and for 10 minutes when the temperature was high and humid. I went.

These results are shown in Table-1.

(Example 2) In place of the amide compound used in Example 1, except for using hydroxyl group-containing amide compound 1.5F obtained by the reaction of 1 mol of 12-hydroxystearic acid and 1 mol of 2-annoethanol, In the same manner as in Example 1, treated magnetic powder, 21-magnetic paint, and magnetic recording medium were obtained. The magnetic recording medium was numbered, and the squareness ratio and abrasion loss were measured according to the method of Example 1. These results are shown in Table-1.

(Example 3) Instead of the amide compound used in Example 1, an amide compound containing a human xyl group obtained by reacting 1 mole of oleic acid chloride with 1-1 nyl of N-(2-oxyethyl)ethylenecyain. Example 1 except that 1.5t was used.
In the same manner as above, treated magnetic powder, magnetic paint, and magnetic recording medium were obtained. The squareness ratio and abrasion loss of the magnetic recording medium were measured according to the method of Example 1. These results are shown in Table-1.

(Example 4) Instead of the amide compound used in Example 1, 1.5f of an amide group-containing amide compound obtained by the reaction of 1 mol of stearic acid and 1 mol of hexamethylenecyanate was used. A treated magnetic powder, a magnetic paint, and a magnetic recording medium were obtained in the same manner as in Example 1, except that the following was used. The squareness ratio and abrasion loss of the magnetic recording medium were measured according to the method ζ of Example 1. These results are shown in Table 1.
Shown below.

(Example 4) Instead of the isocyanate compound used in Example 1, 0
CN-(CHs)@NHcONH(CH leak)m81(O
Isocyanate compound represented by CgHs) 2. O
Further, in place of the amide compound used in Example 1, an anno group-containing aado compound 2.i obtained by reacting 1 mol of dodecenylsuccinic anhydride with 1 mol of ethylene cyanocarbon was prepared. A treated magnetic powder, a magnetic paint, and a magnetic recording medium were obtained in the same manner as in Example 1 except that Ot was used.

The squareness ratio and abrasion loss of the magnetic recording medium were measured according to the method of Example 1. These results are shown in Table-1.

23- (Example 5) Instead of the amide compound used in Example 1, malic acid 1
A treated magnetic powder, a magnetic paint, and a magnetic recording medium were obtained in the same manner as in Example 1, except that the hydroxyl group-containing and compound 1.5y- obtained by reacting 1 mole of dodecylamine with 1 mole of dodecylamine was used. The squareness ratio and abrasion loss of the magnetic recording medium were measured according to the method of Example 1.

These results are shown in Table-1.

(Example 6) The procedure was carried out in the same manner as in Example 1, except that 1.51 mol of a hydroxyl group-containing and compound obtained by the reaction of 1 mol of tartaric acid and 2 mol of octylamine was used instead of the amide compound used in Example 1. 1. A treated magnetic powder, a magnetic paint, and a magnetic recording medium were obtained. Example 1 for the magnetic recording medium
Squareness ratio and wear loss were measured according to the method described in . These results are shown in Table-1.

24- (Example 7) Instead of the incyanato compound used in Example 1, 4
．． 4'-diphenylmethane diisocyanate) 1.5
f, and in place of the amide compound used in Example 1, an amine group-containing amide compound 2.3F obtained by reacting 1 mole of behenic acid with 1 mole of ethylene cyanide.
A treated magnetic powder, a magnetic coating material, and a magnetic recording medium were obtained in the same manner as in Example 1 except that the following was used. The squareness ratio and abrasion loss of the magnetic recording medium were measured according to the method of Example 1. These results are shown in Table-1.

(Large axis diameter 0.35 μm and 1 axis ratio 1/10 used in Comparative Example 1)
To the CO-adhered r-Fe*On 150 P, 4.5 FF of soybean oil lecithin was added as a dispersant, and the magnetic powder was made magnetic in the same manner as in Example 1 without surface treatment. Paint and magnetic recording media were obtained. The squareness ratio and abrasion loss of the magnetic recording medium were measured according to the method of Example 1.

These results are shown in Table-1.

(Comparative Example 2) A magnetic paint and a magnetic recording medium were obtained in the same manner as in Comparative Example 1, except that octyl phosphate (4.59-) was used in place of the soybean oil lecithin used in Comparative Example 1. The squareness ratio and abrasion loss of the magnetic recording medium were measured according to the method of Example 1. These results are shown in Table-1.

=261 Table-1 Patent applicant: Kao Soap Co., Ltd. Agent Mochizuki Keibu 27-1

Claims (1)

[Scope of Claims] 1. - having an amide bond in the molecule and having at least one of a human tetraxyl group or an adeno group, with a molecular weight of 10
0 or more adendo compounds and the following (1) and (I), (1) a polyisocyanate compound with a molecular weight of Zoo to 1000 having 2 or 3 or more incyanato groups in one molecule, (■) Hydrolyzable alkoxysilane group and 1 molecule in one molecule
having a molecular weight of 14 or more isocyanate groups
1. A magnetic recording medium comprising magnetic powder coated with a reaction product with one or more isocyanate compounds selected from the group consisting of 0 to 1,500 inocyanate compounds. 2. An amide compound with a molecular weight of 100 or more is one of the following (1) to
Group A consisting of (3); Group A (1) fatty acids or acid NOSOgen compounds having 6 to 22 carbon atoms; (2) monobasic or polybasic oxyacids having 2 to 22 carbon atoms; Compound (3) Alkenyl or alkyl having 10 to 26 carbon atoms and one or more acids, acid % tetragenides or acid anhydrides selected from acids, acid halides or anhydrides thereof. , Group B consisting of the following (4) to (7), Group B (4) Alkylenethia having 2 to 20 carbon atoms, (5) General formula (wherein, n is an integer of 2 to 10, and R is Hydrogen or carbon number 1~
(6) Alkyl or alkylarane having 6 to 22 carbon atoms (7) Alkanol having 2 to 20 carbon atoms The magnetic recording according to claim 1, which is an amide compound obtained from one or more amine compounds selected from the group consisting of amine compounds and having at least one of a hydrosil group and an amine group. Medium.