JPH03216815A - Magnetic coating material and magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent dropout of magnetic layer without using a base coating material by incorporating silane coupling agent and a surface modifier for the supporting body into the magnetic coating material. CONSTITUTION:The magnetic coating material to form a magnetic layer on a supporting body contains at least one kind of silane coupling agent and one kind of surface modifier for the supporting body respectively. By coating this magnetic coating material on the supporting body, wettability for the supporting body can be improved and the dried magnetic layer has higher adhesion property. Moreover, bonding strength of the binder and magnetic powder in the magnetic layer can be increased to raise the strength of the layer. Thereby, dropout of the layer can be prevented and the layer can be formed at low cost since no base coating material is used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention particularly relates to a magnetic recording medium in which falling off of a magnetic layer from a support is reduced.

BACKGROUND OF THE INVENTION Magnetic recording media such as magnetic tapes and magnetic disks are widely used in the video field, audio field, computer field, and the like. Coating-type magnetic recording media, in which a magnetic coating consisting of magnetic powder, resin, solvent, dispersant, and other additives is applied to a support and dried to form a magnetic coating, are also used as such magnetic recording media. ing.

In recent years, magnetic recording media have been required to have higher recording densities as well as higher reliability, and for this reason, magnetic layers have been formed by fine-graining magnetic powder and filling it with high density. Efforts have been made to make the magnetic layer thinner and to improve the running properties of the magnetic layer.

However, when such improvements are made to the magnetic layer, the adhesion of the magnetic layer to the support, the strength of the magnetic layer, etc. decrease, and the magnetic layer tends to fall off when used as a magnetic recording medium. . Specifically, when used as a magnetic tape, for example, the magnetic layer peels off from the support due to being rubbed by a magnetic head, etc., causing deterioration of the characteristics of the magnetic tape such as increased dropout.
vinegar. In addition, the flakes may land on the magnetic head and cause damage to it. In order to prevent these problems, conventionally, an undercoat consisting of a resin solution made by dissolving polyester resin, polyurethane resin, etc. in an organic solvent is applied onto the support, and a magnetic paint is applied on top of the coating film to form a magnetic layer. It is also being formed.

[Problem to be solved by the invention]

However, when applying the above-mentioned primer to a support and applying magnetic paint on the dried paint film, the organic solvent contained in the magnetic paint causes the paint film to swell. As a result, the smoothness of the interface between the magnetic layer and the primer coating is impaired, and this may cause a decrease in the smoothness of the magnetic layer surface. As a result, problems such as a decrease in output and an increase in output fluctuation occur.

At this time, a polyisocyanate compound etc. is added to the primer,
Another method has been used to crosslink the resin in the primer coating and apply magnetic paint on top of it to prevent it from getting wet or dissolved by solvents, but this method has not yet been shown to be sufficiently effective. In addition, providing a coat of primer in this way increases the number of production lines and increases material costs, resulting in high costs and, for example, the market price is low, as in the case of magnetic tape. This is not desirable at present.

An object of the present invention is to provide an inexpensive magnetic recording medium that prevents the magnetic layer from falling off without using an undercoat.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention includes a silane coupling agent and an interface modifier for the support to which the magnetic paint is applied, in a magnetic paint for forming a magnetic layer on a support. The object of the present invention is to provide a magnetic paint characterized by containing at least one type of each, and a magnetic recording medium using the same. At this time, the silane coupling agent and the surfactant are each added in an amount of 0.1 to 5 parts per 100 parts by weight of the magnetic powder. O
It is preferable to combine them in a proportion of M parts.

Next, the present invention will be explained in detail.

When using a magnetic recording medium in which a magnetic layer is formed by coating and drying a magnetic paint on a support, the magnetic layer may fall off due to two reasons: ■ Decrease in the adhesion of the magnetic layer to the support, ■ Deterioration of the magnetic layer within the magnetic layer. This is a decrease in strength. Therefore, it is necessary to make improvements from these two points.

In view of the above point (2), the present invention adds an interface modifier for the support to a magnetic paint to improve wetting of the support when the magnetic paint is applied to the support. A ring agent is contained in the magnetic layer to strengthen the bond between the binder and the magnetic powder and improve its strength.

The silane coupling agents mentioned above include the following. CH2=CHSi (OCH'l)! (Vinyltrimethoxysilane coupling agent) Methoxysilane cassoubling agent) CH2 -C}IC}120c3H6si (OCH5
)3\/ (T~glycitoxobyltriethoxysilane linking agent) H2NC51{6Si (OC21{5)5 (γ-aminobutylic triethoxysilane linking agent) H2NCONFIC3F16Si (OC21{5) 3(
γ-2-aminoethyl)aminopropyltriethoxysilane casobling agent) HSC3H(,Si(OCH5)3 (γ-Mercaf0 topropyltrimethoxysilane coupling agent) Not limited to these, other silane coupling agents can also be used. However, these can be used singly or in a mixture of 2M or more.

Moreover, the following can be mentioned as the above-mentioned interface modifier.

(b) Amines Beef tallow diamine diolein N! salt Coconut diamine/diadibate, etc. These may be used alone or in combination.

These may be used alone or in combination.

(1) Phosphate esters Monoesters of the following general formula (1) (wherein R-0- is a phenol group, nonylphenol group, dinonylphenol group, tridecylphenol group, oleyl alcohol group, stearyl alcohol group, etc., n represents 2 to 15.) Diester of the following general formula (n) (wherein R'-0- and R2-Q- are the same or different phenol group, nonylphenol group, dinonylphenol group, tridecylphenol group, oleyl Alcohol group, stearyl alcohol group, etc., nSm is the same or different 2 to
Represents I5. ) These monoesters and diesters may be used alone or in combination.

(3) Soybean lecithin (2) Fatty acids Valmitic acid Stearic acid Other surface modifiers are also used, but two or more of these surface modifiers (1) to (2) may be mixed together. It is also used.

The above-mentioned silane coupling agent and interface modifier are each 0.05 to 10.0 parts by weight per 100 parts by weight of magnetic powder,
It is preferably used in an amount of 0.1 to 5.0 g parts.

If it is too small, the effect of preventing magnetic powder from falling off from the magnetic layer will be low, and if it is too large, blooming etc. will occur, which is not preferable.

Examples of the binder resin used in the magnetic recording medium of the present invention include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer-vinyl alcohol copolymer,
Vinyl chloride-vinylacetate-maleic acid copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic acid ester-acrylonitrile copolymer, acrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride Copolymer, methacrylic acid ester-styrene copolymer, thermoplastic polyurethane resin, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylic nitrile copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, polyamide Examples include resins such as synthetic rubbers such as resins, polyvinyl butyral, cellulose derivatives, styrene-butadiene copolymers, polyester resins, and polybutadiene.

Thermosetting resins are also used, such as phenolic resins, epoxy resins, thermosetting polyurethane resins, urea resins, melamine resins, alkynd resins, urea-formaldehyde resins, silicone resins, acrylic reaction resins, and epoxybolyamide resins. , nitrocellulose-melamine resins, mixtures of polymeric polyester resins and isocyanate brepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/polymer diols/triphenylmethane triisocyanates, polyamines Examples include resins and mixtures thereof, and among these, it is preferable to use a combination of resins that have good dispersibility in the ferromagnetic powder.

In addition, as magnetic powder, r-Fe203, 7-Fe2
Examples include crystals of 05 and Fe504, CrO2, r-Fe205 or Fe504 coated with cobalt. In addition, non-oxide magnetic powders such as metal magnetic powders, metal nitride magnetic powders, and metal carbide magnetic powders can also be used, and both can also be used in combination. In addition to the above-mentioned binder resin and magnetic powder, the magnetic paint also contains an organic solvent, and the magnetic paint further contains a dispersant, an abrasive, a filler, an antistatic agent, an antirust agent,
Each component such as a fungicide is appropriately selected and mixed. A known method is used as the manufacturing method.

This magnetic paint is applied to a support such as polyethylene terephthalate film (PET film) using a known coating method such as a doctor blade, reverse roll, gravure roll, or spinner coat, and the magnetic powder is oriented and dried depending on the application. Then, a magnetic recording medium is obtained by subjecting it to surface smoothing treatment.

[Effect]

When the magnetic layer contains a silane coupling agent, the binder of the magnetic layer and the magnetic powder are strongly bonded, and the strength inside the magnetic layer can be increased. Furthermore, since the magnetic paint contains an interface modifier, it is possible to improve the wetting of the paint when it is applied to the support, thereby increasing the adhesion between the magnetic layer and the support. [Example] [Example] Next, an example of the present invention will be described.

Example I Co-containing r-Fe203 100
Weight part (BET 45m/g, FIc=800 0e
), NH2C2H4NHC5H6Si(OCH5)!
o. s ii parts pure water
5.0 parts by weight of an aqueous solution was added, and the mixture was stirred and mixed using a Henschel mixer for 30 minutes. Then 100℃
It was dried for 1 hour. The following paints were manufactured using the surface-treated magnetic powder obtained.

Treated magnetic powder 100 parts by weight Nonylphenyl group-containing 0.5 parts Phosphate ester Vinyl chloride-vinyl acetate copolymer resin 10 parts by weight Polyurethane resin 10 parts by weight Carbon blank 3 parts by weight Alumina
5 parts by weight methyl ethyl ketone
100 parts by weight toluene 1
00 parts by weight Cyclohexanone 100 parts by weight The above mixture was mixed in a ball mill for 10 hours to form a 1 μm
After filtration with a filter, a magnetic paint was obtained.

This magnetic paint was applied onto a 11 μm corona discharge-treated PE film, oriented in a magnetic field, dried, and further calendered to produce a magnetic tape.

Adhesion tests and durability tests were conducted on this, and the results are shown in the table. The test method is as follows.

[Adhesion test]

A cellophane tape was attached to the magnetic layer side of a 3.81w wide magnetic tape, and a constant tension tensile tester was used to test it.
The peeling strength of the magnetic layer from the PET film was measured.

[Durability test]

Using a stationary deck, input the IOK}lz and OdB signals, repeat playback, and measure the number of times until the output drops by -1 dB or more.

Example 2 In Example 1, NH2C2H4NHC3H6Si
(OCJ) 3 to 3. Offile, phosphoric acid ester having nonylphenyl group3. A magnetic paint was prepared in the same manner except that an OM amount was used, and a magnetic tape was produced using this in the same manner as in Example 1. Example I
The results measured in the same manner as above are shown in the table.

Example 3 In Example 1, NH2C2,H4NHC5B(,S
i (OCH3)3 and pure water without treating the magnetic powder, N}12C2H4NtlC3H6Si(OCI{3)3
Magnetic paint was prepared in the same manner except that magnetic powder was directly blended with m.
A magnetic tape was produced in the same manner as in Example 1.

This was also measured in the same manner as in Example 1, and the results are shown in the table.

Example 4 In Example 1, NH2C2H4NHC3H6Si
(OCH5) Instead of 30.5 parts by weight, NH2C2H
A magnetic paint was prepared in the same manner as in Example 1, except that 30.5 parts by weight of 4NH (4H6Si (OC2H5) and 30.5 parts by weight of CHz=CHSi (OCH3) were used. was created.

This was also measured in the same manner as in Example 1, and the results are shown in the table.

Example 5 In Example 4, instead of 0.5 parts by weight of the phosphoric acid ester having a nonylphenyl group, 0.5 parts by weight of the phosphoric acid ester having a nonylphenyl group and 0.5 parts by weight of tallow diamine dioleate were used. A magnetic coating material was prepared in the same manner as in Example 1, except that the same amount was used, and a magnetic tape was produced using this in the same manner as in Example 1.

This was also measured in the same manner as in Example 1, and the results are shown in the table. Example 6 In Example 1, N}12C2}1aNHC5H(,
HSC3 instead of 30.5 parts by weight of Si (OCH3)
A magnetic paint was prepared in the same manner except that 0.5 parts by weight of H1,Si(OCJ)5 was used, and a magnetic tape was produced using this in the same manner as in Example 1. This was also measured in the same manner as in Example 1, and the results are shown in the table.

Comparative Example 1 In Example 1, NH2CZ84N}lc5H et al.
A magnetic paint was prepared in the same manner as in Example 1, except that untreated magnetic powder was used instead of the magnetic powder treated with i (QC}13)3 and pure water. We made magnetic tape. This was also measured in the same manner as in Example 1, and the results are shown in the table.

Comparative Example 2 A magnetic paint was prepared in the same manner as in Example 1, except that the phosphoric acid ester having a nonylphenyl group was not used, and a magnetic tape was produced using this in the same manner as in Example 1. This was also measured in the same manner as in Example 1, and the results are shown in the table.

Comparative Example 3 A magnetic paint was prepared in the same manner as in Comparative Example 1, except that the phosphoric acid ester having a nonylphenyl group was not used, and a magnetic tape was produced using this in the same manner as in Example 1. This was also measured in the same manner as in Example 1, and the results are shown in the table.

From the results in the table above, it can be seen that the examples have good adhesion.

〔Effect of the invention〕

According to the present invention, it is possible to provide a magnetic paint containing a silane casing agent and an interface modifier for the support, so that when this magnetic paint is applied to the support, wetting to the support is improved, and the drying property of the magnetic paint is improved. The adhesion of the magnetic layer can be improved, and the binding force between the binder and the magnetic powder inside the magnetic layer can be increased to increase its strength. This makes it possible to prevent the magnetic layer from falling off even when used as a magnetic recording medium, and since no primer is used, it is possible to provide an inexpensive magnetic recording medium.

January 23, 1990

Claims (3)

[Claims] (1) A magnetic paint for forming a magnetic layer on a support, characterized in that it contains at least one silane coupling agent and at least one interface modifier for the support to which the magnetic paint is applied. magnetic paint. (2) The magnetic paint according to claim 1, wherein the silane coupling agent and the interface modifier are each contained in a ratio of 0.1 to 5.0 parts by weight per 100 parts by weight of the magnetic powder. (3) A magnetic recording medium obtained using the magnetic paint according to claim 1 or 2.