JPH0677305B2 - Magnetic recording medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel magnetic recording medium using a cyanate ester-based specific thermosetting resin composition as a binding resin. The present invention provides a magnetic recording medium which is excellent in workability and wear resistance and has good workability and workability.

[Conventional method and its problems]

Conventionally, as binder resins for magnetic disks, magnetic tapes, etc., rubbers such as polyvinyl chloride, polyvinyl acetate, polyurethane, polybutadiene, etc., epoxy resins, phenoxy resins, acrylic resins, etc. and various modified products thereof have been used. .

However, in recent years, recording on magnetic disks, magnetic tapes, etc.
As the read-out speed becomes faster and the density becomes higher, the heat resistance and wear resistance of the binding resin are insufficient, and more excellent materials are required.

Although a method of using a polyimide resin as a method of satisfying this requirement has been studied, there are various practical problems such as adhesion with magnetic powder, dispersibility of magnetic powder, processability, and workability. There was a problem from the point of solution.

[Means for solving problems]

As a result of intensive studies to meet the above requirements, the inventors of the present invention used the cyanate ester thermosetting resin containing a low crystalline to amorphous thermoplastic saturated polyester resin to solve the above problems. The present invention has been completed by finding a product in which the points are solved, workability, workability, and storage stability are excellent, and the cured product has excellent heat resistance, wear resistance, and adhesion.

That is, the present invention provides a magnetic recording medium in which a magnetic coating material containing a binder and magnetic powder is coated on a substrate to form a magnetic layer, and the magnetic coating material has a cyanato group in the molecule (A). A thermosetting resin composition containing a polyfunctional cyanate ester compound having two or more
To 50 parts by weight and (B) 1 to 50 parts by weight of a low crystalline to amorphous thermoplastic saturated polyester resin,
A magnetic recording medium is characterized by using a thermosetting magnetic paint containing (C) magnetic powder and (D) a surfactant as essential components.

The present invention will be described below.

The cyanate ester resin composition (A) of the present invention comprises a polyfunctional cyanate ester represented by the following general formula (1) and its prepolymer as essential components, and is suitable as a polyfunctional cyanate ester. Is represented by the following general formula (1); R (OCN) m ... (1) (m in the formula is an integer of 2 or more and usually 5 or less, and R is an aromatic organic group, The cyanato group is a compound represented by the formula (1) bound to the aromatic ring of the organic group. To give a concrete example, 1,3-or
1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-, 1,4-, 1,6-, 1,8-, 2,6- or 2,7-dicyanatonaphthalene , 1,3,6-tricyanatonaphthalene 4,4'-dicyanatobiphenyl, bis (4-cyanatophenyl) methane,
2,2-bis (4-cyanatophenyl) propane, 2,2-bis (3,5-dichloro-4-cyanatophenyl) propane, 2,2-
Bis (3,5-dibromo-4-cyanatophenyl) propane,
Bis (4-cyanatophenyl) ether, bis (4-cyanatophenyl) thioether, bis (4-cyanatophenyl) sulfone, tris (4-cyanatophenyl) phosphite, tris (4-cyanatophenyl) phosphate , And cyanate ester obtained by reacting a terminal OH group-containing polycarbonate oligomer with cyanogen halide (USP-4026913), cyanate ester obtained by reacting novolak with cyanogen halide (USP-4022755, U
SP-344807) and so on. In addition to these
8, the same 43-18468, the same 44-4791, the same 45-11712, the same 46-41112,
47-26853, JP-A-51-63149, USP-3553244, 3755402,
Cyanate esters described in 3740348, 3595900, 3694410, and 4116946 can also be used.

Further, the above-mentioned polyfunctional cyanate ester is present or absent in the presence of mineral acid, Lewis acid, salts such as sodium carbonate or lithium chloride, phosphates such as tributylphosphine, organometallic salts such as zinc octylate. It is used as a prepolymer obtained by polymerizing below. These prepolymers generally have a sym-triazine ring formed in the molecule by trimerizing the cyan group in the cyanate ester.

Furthermore, the polyfunctional cyanates mentioned above can also be used in the form of prepolymers with amines. Examples of amines that can be preferably used include meta or para-phenylenediamine,
Meta or para-xylylenediamine, 1,4- or 1,3-cyclohexanediamine, hexahydroxylylenediamine, 4,4'-diaminobiphenyl, bis (4-aminophenyl) methane, bis (4-aminophenyl) ether , Bis (4-aminophenyl) sulfone, bis (4-amino-3)
-Methylphenyl) methane, bis (4-amino-3,5-dimethylphenyl) methane, bis (4-aminophenyl) cyclohexane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4 -Amino-3-methylphenyl) propane, 2,2-bis (4-amino-3-chlorophenyl) propane, bis (4-amino-3-chlorophenyl) methane, 2,
2-bis (4-amino-3,5-dibromophenyl) propane, bis (4-aminophenyl) phenylmethane, 3,4-diaminophenyl-4-aminophenylmethane, 1,1-bis (4-aminophenyl ) -1-Phenylethane and the like.

The above-mentioned polyfunctional cyanate esters, their prepolymers, and prepolymers with amines can be used alone or in the form of a mixture, and those having a number average molecular weight of 300 to 6,000, preferably 300 to 1,500 are usually used. .

The low crystalline to non-crystalline thermoplastic saturated polyester resin of the component (B) of the present invention is mainly composed of an aromatic or aliphatic dicarboxylic acid and an aliphatic or alicyclic diol or a prepolymer thereof. It is polycondensed and imparts particularly flexibility to the component (A).
In the present invention, the number average molecular weight calculated from the number of terminal functional groups is usually 1,500 to 25,000, preferably 5,000 to 22,0.
00 is more preferable because of compatibility and the like. Further, those having a hydroxyl value of 1 to 3 mg KOH / g are preferable. This is because when a free crystalline or non-crystalline thermoplastic saturated polyester resin has an excess of free hydroxyl groups or carboxyl groups, these groups and the cyanato group of the A component gradually react even at room temperature. However, the storage stability of the composition will be poor. In addition, the lower the crystallinity, the better, and the kind and ratio of the amount of the acid and alcohol components to be used are selected.

Examples of aromatic or aliphatic dicarboxylic acids include terephthalic acid, isophthalic acid, malonic acid, succinic acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, and their lower alkyl esters and acid anhydrides. , And a low molecular weight pyrolyzed product of a carboxyl group-terminated saturated polyester resin.

Aliphatic or alicyclic diols or prepolymers thereof include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-
Pentadiol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, polycaprolactone diol, 2,2-dimethylpropanediol, 2,2-bis (4- (Hydroxycyclohexyl) propane, 1,4-dihydroxymethylcyclohexane, trimethylol propane, 1,2,3-trihydroxy propane, tetramethylol methane and the like, which have a low molecular weight due to low crystallinity or non-crystallinity. It is better to use one.

As such a low crystalline to non-crystalline thermoplastic saturated polyester resin, those commercially available from Nippon Synthetic Chemical Industry Co., Ltd. under the trade name "Polyester" and from Toyobo Co., Ltd. under the trade name "Byron" are available. It is suitable.

The (C) component magnetic powder of the present invention is a known magnetic powder such as iron oxide, cobalt-adhered iron oxide, chromium dioxide, barium ferrite, or other fiber metal-based magnetic powder having a particle diameter of 0.007- 1 μm, preferably 0.01 to 0.5 μm spherical,
It has a needle-like shape and various other shapes.

As the surfactant (D) of the present invention, any type can be used, but a fluorine-based surfactant and a silicon-based surfactant are particularly preferable.

The magnetic coating material of the present invention is prepared by using the components (A) to (D) described above as essential components. First, the compounding ratio of the binder resin component containing (A) and (B) as essential components is usually
The component (A) is selected from the range of 99 to 50 parts by weight, preferably 98 to 60 parts by weight, and the component (B) is selected from the range of 1 to 50 parts by weight, preferably 2 to 40 parts by weight.

The amount of the component (C) is not particularly limited, but is usually
The total amount of components (A) and (B) is 30 to 95 parts by weight, preferably
The amount is 40 to 85 parts by weight, and the component (C) is used in an amount of 5 to 70 parts by weight, preferably 15 to 60 parts by weight.

Furthermore, the surface active agent (D) component is 0.
Used in an amount of about 005 to 0.1%.

The present invention uses the above components as essential components, but in order to further impart heat resistance, abrasion resistance, adhesion, flexibility, etc. to the components (A) and (B) used as a binder,
Alternatively, for the purpose of improving workability and processability, other thermosetting monomers or prepolymers, rubbers, thermoplastic resins and the like can be appropriately blended.

As these components, cyanate ester-maleimide resin (Japanese Patent Publication No. 54-30440 etc.), cyanate ester-maleimide-epoxy resin (Japanese Patent Publication No. 52-31279 etc.) and cyanate ester-epoxy resin (Japanese Patent Publication No. 46- No. 41112) and others known in the art, specifically, a single or multiple compound having one or more maleimide groups in a molecule such as bis (4-maleimidophenyl) methane or bis (4-maleimido-3-chlorophenyl) methane. Prepolymers of functional maleimides or amines with these; bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, halogenated bisphenol A type epoxy resin,
Epoxy resins such as halogenated phenol novolac type epoxy resins, polyglycol type epoxy resins, alicyclic epoxy resins; monofunctional or polyfunctional acrylates, methacrylates, allyl (meth) acrylates, acrylates such as epoxy (meth) acrylates And its prepolymers; polyallyl compounds such as diallyl phthalate, divinylbenzene, trialkenyl isocyanurate, trialkenyl-Sym-triazine and their prepolymers; dicyclopentadiene and its prepolymers; thermosetting resins such as phenolic resins:
Resins such as liquid to elastic rubbers such as polybutadiene, butadiene-acrylonitrile copolymer, polychloroprene, butadiene-styrene copolymer, polyisoprene, butyl rubber, and natural rubber, and their low molecular weight of several thousand or less. Materials: Thermoplastic polyurethane resins, vinyl acetate resins and other thermoplastic resins having reactive groups and low molecular weight materials having a molecular weight of about several thousand or less; engineering plastics such as polycarbonate, thermoplastic polyester, polyester carbonate, polyarylate and polyphenylene ether Low molecular weight oligomers with a molecular weight of several thousand or less; polyethylene, polypropylene,
A low molecular weight oligomer of polyolefin such as 4-methylpentene-1 having a molecular weight of several thousands or less; a molecular weight of a fluororesin such as polytetrafluoroethylene, polytetrafluoroethylene-propylene copolymer, perfluoroethylenepropylene copolymer, etc. Low molecular weight oligomers up to about a degree can be added.

Among these components, polyfunctional maleimides, opoxy resins, acrylates and the like are particularly preferably used in terms of heat resistance, abrasion resistance, improvement of adhesion and workability, and these are polyfunctional cyanates. It is preferably used in an amount of 100 parts by weight or less based on 100 parts by weight of the ester.

Although the magnetic coating material of the present invention is cured as it is, a curing catalyst or a curing agent is added in order to ease the curing conditions of the coating film and improve the curing speed. As such a compound, any known compound as a curing catalyst for a cyanate ester resin composition can be used, and amines, imidazoles, organic metal salts, inorganic metal salts, organic peroxides and the like can be used. It is illustrated. Among these catalysts, preferable ones include organic metal salts alone and combined use systems of organic metal salts and organic peroxides. As the organic metal salt, zinc naphthenate, lead stearate, lead naphthenate, zinc octylate, tin oleate, tin octylate, dibutyltin malate, manganese naphthenate, cobalt tethenate, acetylacetone manganese, organic acetylacetone, etc. As a peroxide,
Benzoyl peroxide, lauroyl peroxide, capryl peroxide, acetyl peroxide, parachlorobenzoyl peroxide, di-tert-butyl-di-
Examples include perphthalate. The amount of these curing catalysts used is sufficient within the range of the catalyst amount in the general sense,
For example, it is used in an amount of 10 wt% or less, particularly 5 wt% or less, based on the total resin composition.

Further, for the purpose of improving the storage stability of the composition, for example,
The combined use of chelating agents such as acetylacetone is a preferred embodiment.

Incidentally, in addition to the above-mentioned components, known additives such as dyes, pigments, thixotropic agents, coupling agents, etc. are appropriately added to the magnetic coating composition used in the magnetic recording medium of the present invention. can do.

The above components are mixed to prepare a magnetic coating material of the present invention, which is applied to a substrate such as a plastic film, a sheet, a laminated plate or a metal plate such as aluminum, and dried by heating and curing to obtain the magnetic recording of the present invention. Use as a medium.

The magnetic coating is prepared by a method of mixing without a solvent, which is appropriately used such as a method of using a solvent, but usually acetone, methyl ethyl ketone, tetrahydrofuran, chloroform, acrylonitrile, ethyl acetate, dioxane, methyl isobutyl ketone, methyl cellosolve, xylene, According to a method of preparing a magnetic powder-dispersed solution using an organic solvent such as toluene, dimethylformamide, diethylene glycol dimethyl ether, dimethyl sulfoxide, N-methylpyrrolidone, butyl cellosolve acetate, butyl carbitol acetate and dimethyl phthalate, alone or as a mixture.

The curing conditions naturally vary depending on the resin component used, the type and amount ratio of the curing agent and the catalyst, etc., but normally, the physical properties of the base material used from the range of 100 ° C to 300 ° C and the desired physical property requirements of the magnetic recording medium are required. Take into consideration and select appropriately.

〔Example〕

 Hereinafter, specific examples will be described.

Unless otherwise specified, the parts such as the examples are based on weight.

Example 1 2,2-bis (4-cyanatophenyl) propane at a temperature of 150 ° C.
20 minutes of prepolymer preliminarily reacted for 240 minutes, low crystalline to amorphous thermoplastic saturated polyester resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name; Polyester LP-35, calculated from the number of terminal functional groups Number average molecular weight 16,000, hydroxyl value 6 mgKOH / g) 4 parts and fluorine-based surfactant (Neos Co., Ltd., trade name; Ftergent200) 0.2 parts are dissolved in butyl carbitol acetate 150 parts, and further dissolved in this solution. γ-Fe ₂
76 parts of O ₃ was added and mixed uniformly.

Apply this mixed solution to a polished aluminum plate at 130 ° C
It was cured by heating for 30 minutes and further at 180 ° C. for 3 hours to obtain a good coating film.

The test results of this coating film are shown in Table 1 together with Comparative Example-1.

Comparative Example-1 In Example-1, as the resin component, an epoxy resin (Yukaka Shell Epoxy Co., Ltd., trade name; Epicoat 1001,
Epoxy equivalent 450-500) 20 parts, epoxy urethane resin (Asahi Denka Kogyo KK, trade name; ADEKA RESIN EPU-
6) The same except that 5 parts were used. The results are shown in Table 1.

In Table 1, adhesion is measured by a cross-cut test (cross-cut method), and friction loss is measured by reducing the amount of wear when a magnetic head of 3.0 kg is applied and running at a speed of 1 m / sec for 10 minutes. However, the relative value is shown with 100 in Comparative Example-1.

Example-2 11 parts of prepolymer prepared by pre-reacting 1,4-dicyanatobenzene at 150 ° C. for 4 hours, phenol novolac type epoxy resin (trade name; manufactured by Yuka Shell Epoxy Co., Ltd .; trade name: Epicoat 152, epoxy equivalent 172) 179) 1 part, 8 parts of the same low crystalline to non-crystalline thermoplastic saturated polyester resin as in Example-1, a fluorosurfactant (manufactured by 3M, trade name; Fluor
ad FC17) 0.04 parts, iron acetylacetone 0.01, di-t-
0.2 parts of butyl peroxide and 80 parts of γ-Fe ₂ O ₃ are added to methyl ethyl ketone / butyl carbitol acetate (= 2 /
It was mixed with 170 parts of the mixed solvent of 8).

This mixed solution was applied onto a polyester film so that the coating film thickness would be 10 μm, and heat-cured at 100 ° C. for 2 hours and further at 150 ° C. for 4 hours to obtain a good coating film.

The test results of this coating film are shown in Table 2 together with Comparative Example-2.

Comparative Example-2 In Example-2, an epoxy resin as a resin component (Yukaka Shell Epoxy Co., Ltd., trade name; Epicoat 1001,
Epoxy equivalent 450-500) 14 parts, epoxy urethane resin (Asahi Denka Kogyo KK, trade name; ADEKA RESIN EPU-
6) The same except that 5 parts were used. The results are shown in Table 1.

In Table 2, the adhesive tape test is a method of sticking a polyester film adhesive tape on the coating film, firmly adhering it, and then pulling the adhesive tape strongly to peel off the friction tape at a speed of 20 m / sec. The amount of wear was measured when adhesion and running were performed for 10 minutes, and the value was shown as a relative value with 100 in the case of Comparative Example-2.

[Operations and Effects of the Invention] As is apparent from the detailed description of the invention and Examples and Comparative Examples, the magnetic recording medium of the present invention has excellent heat resistance, abrasion resistance, adhesion to a substrate, and Utilizing the close contact or adhesiveness with the magnetic powder, and also excellent dispersibility of the magnetic powder, workability and safety, practically excellent heat resistance and abrasion resistance. It can be seen that a magnetic recording medium having excellent properties can be provided.

Claims (3)

[Claims] 1. A magnetic recording medium in which a magnetic coating material containing a binder and magnetic powder is coated on a substrate to form a magnetic layer. The magnetic coating material contains a cyanato group in the molecule (A). 99 to 50 parts by weight of a thermosetting resin composition containing a polyfunctional cyanate ester compound having two or more as an essential component, and (B) 1 to 50 parts by weight of a low crystalline to amorphous thermoplastic saturated polyester resin. A magnetic recording medium characterized by using a thermosetting magnetic coating material containing a binder consisting of (C), magnetic powder (D) and a surfactant (D) as essential components. 2. The magnetic recording medium according to claim 1, wherein the low-crystalline to non-crystalline thermoplastic saturated polyester resin (B) has an average molecular weight calculated from the number of terminal functional groups of 5,000 to 22,000. 3. The magnetic recording medium according to claim 1, wherein the low-crystalline to non-crystalline thermoplastic saturated polyester resin (B) has a hydroxyl value of 1 to 30 mg KOH / g.