JP3125107B2 - Composition for magnetic paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic coating composition for a magnetic recording medium such as a magnetic tape.

[0002]

2. Description of the Related Art A magnetic recording medium such as a magnetic tape, a magnetic card, a magnetic disk and the like is usually provided on a non-support such as a polyester film with a ferromagnetic powder, a binder, an organic solvent and, if necessary, another solvent. It is manufactured by applying a magnetic paint composed of additives and the like, curing and drying. In order to obtain excellent accuracy such as high sensitivity, high recording density, high S / N ratio and high reliability required for magnetic recording media, dispersibility of ferromagnetic powder in resin in magnetic paint, It must be excellent in properties such as smoothness, adhesion to a support, and mechanical strength.

[0003] Binders in magnetic coating materials used for magnetic recording media generally used in the past include, for example, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, and polyol. Polyurethane resins, bisphenol A-type phenoxy resins, isocyanates and the like, which are formed by the reaction of phenol and polyisocyanate, have been widely used. In recent years, in particular, in magnetic recording media for VTRs (video tape recorders) and the like, the fineness and the magnetic force of the magnetic powder have been increased, and the packing density of the magnetic powder in the magnetic layer has been increased. Accordingly, a method of obtaining a high reproduction output has been taken.

[0004] As a result, the specific surface area of the magnetic powder has been increased, and the cohesive force has been increased due to the high magnetization, so that the binder of the magnetic paint which has been conventionally used cannot obtain the dispersibility or the surface smoothness of the magnetic powder.

[0005]

According to the present invention, good dispersibility can be obtained even for magnetic powders of these magnetic paints,
An object of the present invention is to obtain a magnetic coating material having excellent compatibility with an isocyanate as a curing agent component and other binder resins when used in combination.

[0006]

The gist of the present invention is that a halogen content of a halogenated bisphenol, a bisphenol and an epihalohydrin is from 0.1 part by weight to 4 parts by weight.
0 parts by weight of the side chain of the halogen-containing phenoxy resin
It is a composition for magnetic paints characterized by containing rubonic acid , or it is preferable to add a phosphorus compound to a halogen-containing phenoxy resin. That is, in the present invention, in a magnetic recording medium such as a magnetic tape, the magnetic recording layer contains a halogen-containing phenoxy resin as a binder component to improve the dispersibility of the magnetic powder and the surface smoothness of the magnetic layer. The durability of the resulting magnetic recording medium,
It is intended to improve magnetic characteristics and the like.

The phenoxy resin used in the present invention can be produced, for example, from a halogenated bisphenol or a bisphenol and an epihalohydrin, or a halogenated bisphenol or an epoxy resin and a bisphenol and / or It is produced by addition polymerization reaction from bisphenols, addition polymerization reaction from bisphenols epoxy resin and halogenated bisphenols and / or bisphenols, or a combination thereof. The basic structure of the halogen-containing phenoxy resin used in the present invention is schematically represented by the following structural formula (1).

[0008]

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In the formula, Xi and Xi 'may be the same or different and are a halogen atom, that is, a chlorine atom, a bromine atom, an iodine atom or a fluorine atom, and R1 and R2 are

[0010]

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Or -CH2-, -SO2-, i,
i ′ represents an integer of 1 to 4, and n and m represent an integer of 1 or more.

The content of halogen atoms in the structural formula (1) has a significant effect on the dispersibility with magnetic powder, and requires a range of 0.1 to 40 parts by weight. The effect can be obtained even with a very small halogen content of 0.1 part by weight, but more preferably 0.5 to 30 parts by weight. When the amount is less than 0.1 part by weight, the dispersibility with the magnetic powder is inferior, and when the amount is more than 40 parts by weight, the compatibility with the polyurethane and the solubility with the organic solvent are inferior, which is not suitable for this purpose.

[0013] Of the halogenated bisphenols used as a raw material of the phenoxy resin, it is most effective that the halogen atom is bromine. Typically,
2,2 bis (4-hydroxy-2,3,5,6 tetrabromophenyl) propane, 2,2 bis (4-hydroxy-2,3,5,6 tetrabromophenyl) methane, 2,
2, bis (4-hydroxy-2,3,5,6 tetrabromophenyl) sulfide and the like. The halogenated bisphenols epoxy resin can be obtained from the above-mentioned bisphenols and epihalohydrin by a known method.

Bisphenols are typically 2,2bis (4-hydroxy) propane, 2,2bis (4-hydroxy) methane, 2,2bis (4-hydroxy) sulfide, 2,2bis (4-hydroxy) sulfone, 3,
4,5,6-dibenzo-1,2-oxaphosphane-2
-Oxide hydroquinone.

The bisphenol epoxy resin can be obtained from the above bisphenol and epihalohydrin by a known method. The halogen-containing phenoxy resin of the present invention includes the above-mentioned halogenated bisphenols, bisphenol-
It can be easily produced by a known method by adjusting the ratio of the number of moles of the reaction product and the epoxy resin or epihalohydrin.

In the present invention, when a carboxylic acid group is introduced as a hydrophilic polar group or a phosphorus compound is introduced into the above-mentioned phenoxy resin, the phenoxy resin exhibits a higher affinity for magnetic powder and exhibits a more effective effect. it can. In order to introduce these hydrophilic groups, a known method in the presence or absence of a catalyst in the presence of an organic solvent and a reagent having an active group that undergoes an addition reaction with a secondary hydroxyl group present in the side chain of the halogen-containing phenoxy resin of the present invention. Can be produced by a grafting reaction.

The reagent which reacts with the secondary hydroxyl group typically includes acid anhydrides. More specifically, maleic anhydride, succinic anhydride, terephthalic anhydride, trimellitic anhydride, and the like. It is effective that the ratio of the introduced group is in the range of 0.5% to 100% of the total hydroxyl groups in the molecule.

Further, a phosphorus compound is introduced into the main chain by copolymerization. Specifically, dihydroxyphosphoric acid monoester, 3,4,4
5,6-dibenzo-1,2-oxaphosphane-2-oxide hydroquinone. Alternatively, as a compound introduced by reacting a phosphorus compound with an epoxy group remaining at the terminal, typically, monohydroxyphosphoric diester, 3,4,5,
6-dibenzo-1,2-oxaphosphane-2-oxide and the like. Of course, the addition of the above-mentioned phosphorus compounds and other triphosphates can also be used. It is effective that the phosphorus compound is incorporated in an amount of 0.01 to 1 part by weight as phosphorus in the total amount of the resin.

The composition for a magnetic coating material according to the present invention is obtained by adding the above-mentioned halogen-containing phenoxy resin to another binder resin,
Components such as a hardening agent, magnetic powder, other additives (antistatic agent, lubricant, abrasive, etc.) and an organic solvent are added as required. Then, the composition for magnetic paint is applied on a magnetic recording medium to form a magnetic layer. Therefore,
As an example of the magnetic layer, a ferromagnetic powder prepared by dissolving a halogen-containing phenoxy resin of the present invention and isocyanate as a curing agent in an organic solvent is applied to the surface of a non-magnetic support of a polyester film. , Cured and dried.

Hereinafter, each component of the magnetic coating composition will be described. The halogen-containing phenoxy resin, which is a main part of the present invention, is characterized in that the polarizability of the halogen atom substituted by the aromatic skeleton improves the affinity with the magnetic powder, and furthermore, a part of the inner chain of the molecule is placed on the carboxylic acid group. Alternatively, by introducing a phosphorus compound into the molecule, the polarity can be increased, the crosslinking density by the curing reaction with isocyanate can be increased, and a durable coating film can be formed. In addition, since it has a hydroxyl group on the inner side of the molecule, it has adhesion to the non-support layer, and has an effect of dispersing the magnetic powder, and thus providing electromagnetic conversion characteristics and surface smoothness of the coating film. The halogen-containing phenoxy resin can be used in combination with another binder resin (for example, a polyurethane resin) in that it has a function as a binder.

As the curing agent component, an isocyanate which reacts with a hydroxyl group of a side chain of the halogen-containing phenoxy resin can be used. In order to accelerate the curing by the isocyanate, an organic tin or amine catalyst is used. Can also be used. The combined polyurethane resin can be synthesized by a reaction between a polyol and a polyisocyanate.

Examples of usable polyols include organic dibasic acids such as phthalic acid, adipic acid, dimerized linoleic acid, and maleic acid, and ethylene glycol, propylene glycol, butylene glycol, and diethylene glycol. Or polyvalent alcohols such as trimethylolpropane, hexatriol, glycerin, hexanetriol, trimethylolethane, pentaerythritol and the like, or these glycols and polyvalent alcohols. Polyester polyol synthesized by reaction with any two or more kinds of polyols selected from alcohols; or synthesized from caprolactams such as s-caprolactam and α-1-caprolactam Lactone-based polyester polyol; synthesized from ethylene oxide, propylene oxide, etc. That polyether - Teruporio - le, and the like. These polyols are reacted with isocyanate compounds such as tolylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, and meta-xylylene diisocyanate to form urethane-modified polyester. Polyurethane and polyether polyurethane are synthesized. It may be in the form of a urethane resin or a urethane prepolymer containing free isocyanate groups and / or hydroxyl groups, or may be one without these reactive end groups. Polyurethane, urethane prepolymer-urethane elastomer-
It is made by a known method. Of these, those containing free isocyanate also act as a curing agent for the halogen-containing phenoxy resin.

The ferromagnetic powder used for the magnetic layer includes ferromagnetic iron oxide particles, ferromagnetic chromium dioxide, ferromagnetic alloy powder,
Hexagonal barium ferrite fine particles, iron nitride, metal powder, and the like. Further, a dispersant, a lubricant, an abrasive, an antistatic agent, a rust inhibitor and the like may be added to the magnetic layer as other additives.

These constituent materials are adjusted by dissolving them in an organic solvent. Typically, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; methyl acetate, ethyl acetate, and glycol monoethyl ether; Esters, glycol ethers such as glycol dimethyl ether and dioxane, aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as hexane and hiptan, chlorinated hydrocarbons and the like. A mixed solvent is mentioned. The magnetic paint comprising the above components is used in an amount of 5 to 400 parts, preferably 10 to 200 parts by weight, of the binder resin component based on 100 parts of the magnetic powder.

As a method for applying the magnetic coating material of the present invention on a support, a general coating method for coating materials can be used. The applied magnetic layer is excellent in dispersibility with the magnetic powder using the magnetic paint of the present invention by subjecting the magnetic powder in the layer to a treatment for orienting the magnetic powder as necessary, and then curing and drying the formed magnetic layer. A magnetic recording medium having excellent surface smoothness and durability can be obtained.

(Function) The halogen-containing phenoxy resin, which is a binder in the magnetic coating composition of the present invention, contains a specific amount of a substituted halogen atom substituted in an aromatic skeleton.
By containing a hydroxyl group, a carboxylic acid group, a phosphorus compound or the like as a polar group in the molecule, the affinity for the magnetic powder is greatly improved, and the finely divided magnetic powder can be dispersed well. Further, since it has excellent compatibility with other binder components and curing agent components, the strength, surface smoothness and durability of the coating film after curing and crosslinking can be obtained.

[0027]

The present invention will be specifically described below with reference to examples.

Synthesis Example 1 191 parts of bisphenol A type epoxy resin YD-128 (manufactured by Toto Kasei) having an epoxy equivalent of 186.5 g / eq and tetrabromobisphenol A (hereinafter abbreviated as TBA) 17
0 parts and 39 parts of bisphenol A (hereinafter abbreviated as BPA) are dissolved in 200 parts of cyclohexanone, and the temperature is increased while stirring in a nitrogen atmosphere. After adding 0.1 part of trimethylammonium chloride as a catalyst and reacting at 160 ° C. for 5 hours, 200 parts of toluene was added and anhydrous maleic anhydride was added.
Acid is added in an amount of 1 mol% of the total hydroxyl groups and triethyl alcohol is added.
Min is added to the acid anhydride at 0.5% by weight,
After reacting for 4 hours, slowly add 200 parts of methyl ethyl ketone.
Diluted separately, bromine content 25% by weight, hydroxyl group 1 mol%
A maleic acid grafted resin was obtained.

Synthesis Example 2 In Synthesis Example 1, maleic anhydride was replaced with 10 moles of all hydroxyl groups.
The procedure was performed in the same manner as in Synthesis Example 1 except that the compound was added in an amount of 0.1%.
The obtained resin has a bromine content of 20% by weight and a hydroxyl group of 10 mol.
% Maleic acid grafted resin was obtained.

Synthesis Example 3 In Synthesis Example 1, maleic anhydride was replaced with succinic anhydride.
Except having changed, it implemented similarly to the synthesis example 1. Got
The resin has a bromine content of 25% by weight and a hydroxyl group of 1 mol%.
A citric acid grafted resin was obtained.

Synthesis Example 4 YD-128, 192 parts, TBA 170 parts, BPA3
5.8 parts and 200 parts of cyclohexanone were charged, Synthesis Example 1
After reacting for 5 hours, dilute with 200 parts of toluene
After cooling to 100 ° C., the phosphorus content is 13% by weight,
2.2 parts of monoisodecyl phosphate having an acid value of 430 were gradually added.
Was dropped. After further reacting for 2 hours, methyl ethyl
Diluted with 200 parts of ketone. The resulting resin contains bromine
The amount was 25 % by weight and the phosphorus content was 0.07% by weight.

Synthesis Example 5 YD-128, 207.7 parts, TBA 170 parts, BPA
79.3 parts, 3, 4, 5, 6- with a 9.5% by weight phosphorus content
Dibenzo-1,2-oxaphosphane-2-oxide
Hydroquinone 6 parts Cyclohexanone 200 parts Synthesis Example 1
Was synthesized in the same manner as described above. The resulting resin has a bromine content of 25
% And the phosphorus content was 0.14% by weight.

Synthesis Example 6 YD-128, 188.7 parts, TBA 170 parts, BPA
37.5 parts, cyclohexanone 200 parts charged, synthesis example
After reacting in the same manner as in 1, 3, 4, 5, 6-dibenzo
3.8 parts of -1,2-oxaphosphane-2-oxide
Was added, and the mixture was further reacted for 4 hours. Then toluene 20
0 parts and 200 parts of methyl ethyl ketone were added.
The obtained resin had a bromine content of 25% by weight and a phosphorus content of 0.1%.
It was 13% by weight.

Synthesis Example 7 YD-128, 238.8 parts, TBA 34 parts, BPA1
Except for 23.4 parts, it was synthesized in the same manner as in Synthesis Example 10. Profit
The resin obtained had a bromine content of 5% by weight and a phosphorus content of 0.13%.
% By weight.

Synthesis Example 8 YD-128, 240.3 parts, TBA 34 parts, BPA 1
After charging 24.3 parts and 200 parts of cyclohexanone and reacting for 5 hours in the same manner as in Synthesis Example 1, diluting with 200 parts of toluene and cooling to 100 ° C., the phosphorus content was 14.7.
% By weight , 1.4 parts of dibutyl phosphate having an acid value of 272
After dropwise addition and reaction at 100 ° C. for 2 hours, the mixture was diluted with 200 parts of methyl ethyl ketone. The resin was found to have a bromine content of 5 wt% was phosphorus content 0.0 5 wt%.

Synthesis Example 9 YD-128, 70.2 parts, YDB-400, 142.
Synthesized in the same manner as in Synthesis Example 1 , except for 1 part and 187.7 parts of TBA.
Thus, a resin having a bromine content of 45 % by weight was obtained.

[0037]

[0038]

[0039]

A magnetic paint using each binder resin according to the above synthesis example will be described together with a comparative example. The coating compositions of the examples and comparative examples were prepared as the following compositions. Magnetic powder (CO-γ-Fe ₂ O ₃ ) 80 parts Synthetic resin (resin of synthesis example and comparative example) 10 parts Polyurethane N-2304 (manufactured by Nippon Polyurethane) 10 parts Cyclohexanone 25 parts Toluene 50 parts Methyl ethyl ketone 75 parts

Each of the above compositions was applied to a paint conditioner.
For 4 hours, and uniformly mixed to prepare magnetic paints. This magnetic paint is applied to one side of a 15 μm-thick polyethylene terephthalate film by dry coating 10
It was applied to a thickness of μm. The sample thus obtained was dried at room temperature for 10 minutes and then at 60 ° C. for 24 hours, and the gloss of the obtained coating film was measured. The results are shown in Table 1.

[0042]

[Table 1]

The synthetic resins of Comparative Examples 1 to 3 in Table 1 are as follows. * 1 Synthetic resin of Comparative Example 1: vinyl chloride vinyl acetate resin (VACH: VAGH) * 2 Comparative Example 2 Synthetic resin: BPA-type phenoxy resin (Toto Kasei: YP-50) Comparative Example 3 Synthetic resin: Synthetic example 13 resin * 3 In the column of compatibility, a circle indicates compatibility and a cross indicates that they are not compatible.

[0044]

As described above, in the present invention, as the magnetic coating material, halogen-containing bisphenols, bisphenols and epihalohydrin having a halogen content of 0.1 to 40 parts by weight. By including a phenoxy resin, the dispersibility of the magnetic powder is improved, resulting in high sensitivity, high recording density, and high S / N.
The effect is that a magnetic recording medium having excellent accuracy such as ratio and high reliability can be obtained.

Continuation of the front page (56) References JP-A-61-57640 (JP, A) JP-A-7-216270 (JP, A) JP-A-4-93375 (JP, A) JP-A-2-253511 (JP) , A) JP-A-58-79060 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 171/10 C09D 5/23 G11B 5/702 CA (STN) CAOLD (STN) REGISTRY (STN) WPIDS (STN)

Claims (2)

(57) [Claims] 1. A halogen-containing phenoxy resin comprising a halogenated bisphenol, a bisphenol and an epihalohydrin having a halogen content of 0.1 to 40 parts by weight, wherein a carboxylic acid is contained in a side chain. Characteristic composition for magnetic paint. 2. The halogen content of halogenated bisphenols, bisphenols, epihalohydrin and phosphorus compounds is from 0.1 to 40 parts by weight, and the phosphorus compounds are copolymerized in the main chain by copolymerization. A composition for a magnetic coating material, comprising a halogen-containing phenoxy resin introduced into the composition.