JPH0125208B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic material and a method for manufacturing the same. Surfactants conventionally used to improve the dispersibility of powdered magnetic substances in the production of magnetic materials include fatty amine soaps, polyhydric alcohols, fatty acid esters, polyoxyethylene alkyl ether phosphates, Polyoxyethylene alkyl phenyl ether phosphates and the like are known, and among them, specific polyoxyethylene alkyl phosphates and polyoxyethylene alkyl phenyl phosphates are known to be desirable. However, as the demand for improving the performance of magnetic materials has increased in recent years, there has been a strong desire to develop surfactants that are particularly suitable for this purpose. As a result of various studies in response to such demands, the present inventors found that the compound represented by the general formula below is particularly suitable for improving the dispersibility of powdered magnetic substances, and has excellent thermal stability during high-temperature processing. The present invention was based on the findings that it is excellent in terms of low foaming properties and low foaming properties, and that it can improve the magnetic properties of magnetic recording media. In other words, the first principle of the present application is the general formula (However, R is a nonylphenyl group, an octylphenyl group, an oleyl group, or an alkyl group having 12 to 16 carbon atoms, R' is an alkylene group, and (R'O) _o is
A mixed polyoxyalkylene group of C ₂ H ₄ O and C ₃ H ₆ O groups, with 2 to 7 moles of C ₂ H ₄ O groups and 2 moles of C ₃ H ₆ O groups.
It is a mixed polyoxyalkylene group containing ~7 mol and in which the C ₂ H ₄ O group and the C ₃ H ₆ O group are randomly addition-polymerized. phosphoric acid monoester compound represented by (n is an integer from 4 to 14 and represents the number of added moles),
A magnetic material characterized by containing at least one of a phosphoric acid diester compound and a derivative thereof. Moreover, the second invention of the present application is based on the general formula (However, R is a nonylphenyl group, an octylphenyl group, an oleyl group, or an alkyl group having 12 to 16 carbon atoms, R' is an alkylene group, and (R'O) _o is
A mixed polyoxyalkylene group of C ₂ H ₄ O and C ₃ H ₆ O groups, with 2 to 7 moles of C ₂ H ₄ O groups and 2 moles of C ₃ H ₆ O groups.
It is a mixed polyoxyalkylene group containing ~7 mol and in which the C ₂ H ₄ O group and the C ₃ H ₆ O group are randomly addition-polymerized. phosphoric acid monoester compound represented by (n is an integer from 4 to 14 and represents the number of added moles),
This method of producing a magnetic material is characterized by immersing a powdered magnetic substance in an aqueous solution containing at least one of a phosphoric acid diester compound and a derivative thereof, and then filtering and drying the powdered magnetic substance. Furthermore, the third invention of the present application is based on the general formula (However, R is a nonylphenyl group, an octylphenyl group, an oleyl group, or an alkyl group having 12 to 16 carbon atoms, R' is an alkylene group, and (R'O) _o is
A mixed polyoxyalkylene group of C ₂ H ₄ O and C ₃ H ₆ O groups, with 2 to 7 moles of C ₂ H ₄ O groups and 2 moles of C ₃ H ₆ O groups.
It is a mixed polyoxyalkylene group containing ~7 mol and in which the C ₂ H ₄ O group and the C ₃ H ₆ O group are randomly addition-polymerized. phosphoric acid monoester compound represented by (n is an integer from 4 to 14 and represents the number of added moles),
This is a method for producing a magnetic material, which comprises blending at least one of a phosphoric acid diester compound and a derivative thereof into a magnetic paint and processing the mixture. In the compounds represented by the general formulas (1) and (2) according to the present invention, R in the general formula is a nonylphenyl group, an octylphenyl group, an oleyl group, or an alkyl group having 12 to 16 carbon atoms. If R is another alkyl group or alkylphenyl group, the desired dispersibility effect may not be obtained. (R′O) _o is a mixed polyoxyalkylene group,
Particularly preferred is a mixture of C ₂ H ₄ O and C ₃ H ₆ O groups in substantially equimolar amounts. When the amount of C ₂ H ₄ O groups is less than the above range or the amount of C ₃ H ₆ O groups is more than the above range, aqueous treatment becomes difficult and the desired effect cannot be obtained. Furthermore, as the number of C ₂ H ₄ O groups increases or the number of C ₃ H ₆ O groups decreases, the dispersibility improving effect of the present invention becomes smaller. n is an integer of 4 to 14 and represents the number of moles added, but is preferably 6 to 10 from the viewpoint of effectiveness. The compounds according to the present invention include alkylphenols such as nonylphenyl groups and octylphenyl groups, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, oleyl alcohol, and carbon atoms having 12 to 15 carbon atoms by the oxo method. It is produced by a known method (random addition) in which a basic catalyst or an acidic catalyst is added to an alcohol such as a mixed synthetic alcohol, and ethylene oxide and propylene oxide are simultaneously introduced and added at a high temperature. Generally, ethylene oxide and propylene oxide are mixed uniformly in a liquefied state in advance and reacted, but a method is adopted in which they are each introduced separately and continuously at the same time at a flow rate that corresponds to the ratio of the amount added. There is no problem. The thus obtained polyoxyalkylenated alkylphenol and polyoxyalkylenated alcohol are phosphoric acid esterified by a known method using a known phosphorylating agent such as phosphorous oxychloride or phosphorus pentoxide, thereby producing the compound of the present invention. is obtained. Further, the phosphoric acid ester compound thus obtained is usually a mixture containing a phosphoric acid monoester compound and a phosphoric acid diester compound as main components, but a phosphoric acid triester compound may be partially included. In addition, as a derivative of the compound of the above general formula,
Examples thereof include alkali metal or alkaline earth metal salts, ammonium salts, and amine salts. Powdered magnetic substances used in the production of the magnetic material of the present invention include r-Fe ₂ O ₃ , magnetite (Fe ₂ O ₄ ), and bertholed iron oxide (FeOx, 1.33
<X<1.5), those modified with cobalt, manganese, nickel, iron, zinc, chromium, etc., powders of metallic iron and its alloys, and ferromagnetic chromium dioxide. They can be used alone or in appropriate combinations. In order to produce a magnetic material containing a compound (surfactant) represented by the above general formula in the method of the present invention, (1) an aqueous solution in which the surfactant is dissolved or suspended in water, toluene, kerosene, (2) A method of adsorbing a surfactant to the particle surface of the magnetic powder by immersing a powdered magnetic substance in a non-aqueous liquid dissolved or suspended in an organic solvent such as methyl ethyl ketone, chloroform, ethanol, or ethyl acetate; (2) the above-mentioned (1) ), a method in which an aqueous or non-aqueous liquid is sprayed onto a powdered magnetic material and a surfactant is attached to the particle surface of the powdered magnetic material; (3) a method in which the powdered magnetic material is dispersed in a resin binder to create a magnetic This can be done by adding a surfactant when producing a paint. Among these methods, the method of immersing a powdered magnetic material in an aqueous solution of a surfactant is more effective in terms of uniformly adsorbing the surfactant onto the particle surface of the powdered magnetic material and in terms of processing operations. This is the preferred method. In the present invention, the added amount of the surfactant related to the above general formula is:
Preferably 0.05-8% based on the weight of powdered magnetic material
It is 0.1-5%. If the amount added is too small than the above range, the desired effect cannot be obtained, and if it is too large, the strength of the magnetic coating may be impaired, or the surfactant may bleed onto the coating surface, causing various defects. This is not desirable. Examples of the resin binder used in the present invention include various resins such as vinyl, cellulose, urethane, epoxy, phenoxy, and acrylic resins. According to the present invention, as is clear from the Examples and Comparative Examples described later, the compatibility of the powdered magnetic substance with the resin binder is particularly improved and dispersed compared to magnetic materials using phosphate ester compounds other than the present invention. A magnetic recording medium with improved magnetic properties can be obtained. Furthermore, the surfactant of the present invention can be used, for example, at a concentration of 200
It is extremely stable without decomposition even when treated at high temperatures around ℃, so it can provide the desired dispersibility, and also exhibits excellent effects such as less foaming during immersion treatment in aqueous systems. . Examples and Comparative Examples (1) Production A of surfactants according to the present invention 1 mole of nonylphenol (880 parts) and caustic potash (5 parts) were charged in an autoclave reactor,
After dehydration under reduced pressure, alkylene oxide (2040 parts), which is a mixture of 5 moles of ethylene oxide (880 parts) and 5 moles of propylene oxide (1160 parts) in a liquefied state, was introduced at 120 to 145°C, and the mixture was heated to a pressure of 5 kg/cm ² or less. Addition polymerization (hereinafter referred to as random addition) is carried out under the following conditions to obtain poly(5)oxyethylene/poly(5)oxypropylene nonyl phenyl ether (ethylene oxide/propylene oxide = 5/5 molar ratio, random addition product). Furthermore, the obtained poly(5)oxyethylene/poly
(5) Oxypropylene nonyl phenyl ether 1
0.4 mole (227 parts) of phosphorus pentoxide in mole (2920 parts)
A liquid substance containing 60% phosphoric acid monoester and 34% phosphoric diester was obtained. It is referred to as surfactant A according to the present invention. B Using the same equipment and method as surfactant A, a mixture of 3 moles of ethylene oxide and 3 moles of propylene oxide is randomly added to 1 mole of nonylphenol, and then 0.5 mole of phosphorus pentoxide is added to 1 mole of the resulting adduct. A viscous liquid substance containing 65% phosphoric acid monoester and 31% phosphoric diester was obtained. It is referred to as surfactant B according to the present invention. C Using the same apparatus and method as surfactant A, a mixture of 5 moles of ethylene oxide and 5 moles of propylene oxide was randomly added to 1 mole of oleyl alcohol, and then 0.8 mole of phosphorus oxychloride was added to 1 mole of the resulting adduct. were reacted, hydrolyzed, washed with water and dehydrated to obtain an oily substance containing 71% phosphoric acid monoester and 24% phosphoric diester.
It is referred to as surfactant C according to the present invention. D Using the same apparatus and method as surfactant A, a mixture of 3 moles of ethylene oxide and 3 moles of propylene oxide was randomly added to 1 mole of tridecyl alcohol, and then 0.4 phosphorus pentoxide was added to 1 mole of the resulting adduct. The moles were reacted to obtain an oily substance containing 70% phosphoric acid monoester content and 25% phosphoric acid diester content. It is referred to as surfactant D according to the present invention. E Using the same equipment and method as surfactant A, 2 moles of propylene oxide were added to 1 mole of tridecyl alcohol, and then a mixture of 4 moles of ethylene oxide and 4 moles of propylene oxide was randomly added. 0.4 phosphorus pentoxide per mole of the obtained adduct
59% phosphoric acid monoester content,
An oil containing 33% phosphodiester content was obtained. It is referred to as surfactant E according to the present invention. F Using the same apparatus and method as surfactant A, a mixture of 3 moles of ethylene oxide and 3 moles of propylene oxide is randomly added to 1 mole of octylphenol, and then 0.4 mole of phosphorus pentoxide is added to 1 mole of the obtained adduct. were reacted to obtain a liquid material containing 65% phosphoric acid monoester and 30% phosphoric diester. Surfactant F according to the present invention
shall be. G Using the same equipment and method as surfactant A, a mixture of 5 moles of ethylene oxide and 5 moles of propylene oxide was randomly added to 1 mole of tridecyl alcohol, and then 0.4 phosphorus pentoxide was added to 1 mole of the resulting adduct. The moles were reacted to obtain an oil containing 60% phosphoric acid monoester and 33% phosphoric diester. It is referred to as surfactant G according to the present invention. H Using the same equipment and method as surfactant A, a mixture of 3 moles of ethylene oxide and 3 moles of propylene oxide is randomly added to 1 mole of lauryl alcohol, and then 0.4 mole of phosphorus pentoxide is added to 1 mole of the resulting adduct. were reacted to obtain a liquid material containing 67% phosphoric acid monoester and 28% phosphoric diester. Surfactant H according to the present invention
shall be. I Using the same apparatus and method as for surfactant A, a mixture of 5 moles of ethylene oxide and 5 moles of propylene oxide was randomly added to 1 mole of myristyl alcohol, and then 0.4 mole of phosphorus pentoxide was added to 1 mole of the resulting adduct. A liquid material containing 60% phosphoric acid monoester and 32% phosphoric diester was obtained. It is referred to as surfactant I according to the present invention. J Using the same equipment and method as surfactant A, a mixture of 5 moles of ethylene oxide and 5 moles of propylene oxide was randomly added to 1 mole of cetyl alcohol, and then 0.4 mole of phosphorus pentoxide was added to 1 mole of the resulting adduct. A viscous liquid substance containing 58% phosphoric acid monoester and 34% phosphoric diester was obtained. It is referred to as surfactant J according to the present invention. K Using the same equipment and method as surfactant A, Dovanol 23 (C ₁₂ min 43%, C ₁₃ min 56%) manufactured by Mitsubishi Yuka was used.
%, C ₁₄ min A mixture of 3 moles of ethylene oxide and 3 moles of propylene oxide is randomly added to 1 mole of synthetic alcohol containing 1%, and then 0.4 mole of phosphorus pentoxide is added to 1 mole of the resulting adduct. An oily substance containing 67% phosphoric acid monoester and 28% phosphoric diester was obtained. It is referred to as surfactant K according to the present invention. (2) Manufacture of comparative surfactant L Add 9 moles of ethylene oxide to 1 mole of tridecyl alcohol, and react 0.4 moles of phosphorus pentoxide with 1 mole of the obtained adduct to obtain a phosphoric acid monoester content of 62%, phosphorus A liquid material containing 32% acid diester content was obtained. This is a comparative surfactant L according to the present invention. M 9 moles of ethylene oxide were added to 1 mole of tridecyl alcohol, and then 2 moles of propylene oxide were added (block addition). Obtained adduct 1
By reacting 0.4 mol of phosphorus pentoxide with mol, the phosphoric acid monoester content is 59% and the phosphoric acid diester content is 35%.
A liquid substance containing . This is a comparative surfactant M according to the present invention. N 1 mole of nonylphenol to 6 propylene oxide
mol and then 2 moles of ethylene oxide (block addition). One mole of the obtained adduct was reacted with 0.4 mole of phosphorus pentoxide to obtain an oily substance containing 61% phosphoric acid monoester and 35% phosphoric diester. It is referred to as comparative surfactant N according to the present invention. (3) Treatment of powdered magnetic substances R-
Fe ₂ O ₃ powder (coercive force 365 oersted, saturation magnetization
73emu/g, average major axis diameter approximately 0.4μm, axial ratio approximately 7:
1) 10 g was added, stirred for 1 hour, filtered, and the resulting filtrate was dried at 110° C. for 24 hours to obtain magnetic powder for magnetic recording media. (The processing amount of surfactant is r-
(1% by weight and 4% by weight based on Fe ₂ O ₃ ) When preparing an aqueous liquid, almost no foaming was observed when using the surfactant according to the present invention, but especially when using the comparative surfactant N. In this case, a uniform aqueous liquid could not be obtained and the r-Fe ₂ O ₃ powder could not be processed. (4) Manufacture of magnetic paint and magnetic recording medium The magnetic powder obtained in the previous item (3) and untreated r-Fe ₂ O ₃ powder that has not been treated with a surfactant are used and blended in the following proportions. A magnetic coating material was prepared by sufficiently kneading it in a ball mill, and this was applied to a polyester film in a conventional manner, oriented, and dried to obtain a magnetic recording medium with a magnetic coating film approximately 8 μ thick. (1% treatment) (4% treatment) Magnetic powder...101 parts by weight 104 parts by weight PVC chloride-vinyl acetate copolymer...15 〃 15 〃 Dioctyl phthalate...5 〃 5 〃 Toluene...122 〃 122 〃 Methyl ethyl ketone...110 〃 110 〃 ( 5) Characteristics of magnetic recording medium For the magnetic recording medium obtained in the previous section (4), the coercive force (Hc), residual magnetic flux density (Br), saturation magnetic flux density (Bm), and squareness ratio (Br/Bm) were measured using the usual methods. ) and orientation (OR) were measured, and the results shown in Table 1 were obtained.

[Table] Example 2 and Comparative Example ₂ In Example ₁ , iron oxide (coercive force 645 oersted, saturation magnetization
78emu/g average major axis diameter approx. 0.4μm, axial ratio approx. 10:1)
using surfactant B according to the present invention.
A magnetic recording medium was obtained in the same manner except that it was treated with 4% by weight of each of Comparative Surfactant L and the magnetic properties of this medium were measured, and the following results were obtained.

[Table] Example 3 and Comparative Example 3 In Example 1, the r-Fe ₂ O ₃ powder was added to the surfactant B according to the present invention and the comparative surfactant L.
A magnetic recording medium was obtained in the same manner except that it was treated with a 0.1% aqueous solution and then dried at 200°C for 24 hours.
When the magnetic properties of this material were measured, the following results were obtained.

[Table] Example 4 and Comparative Example 4 Surfactant G according to the present invention or comparative surfactant L was blended in the following proportions and sufficiently kneaded in a ball mill to obtain a magnetic paint. A magnetic paint containing no surfactant was also obtained. The r-Fe ₂ O ₃ used here has a coercive force of 360 oersted, a saturation magnetization of 71 emu/g, an average major axis diameter of approximately 0.4 μm, and an axial ratio of approximately
It was 10:1. Furthermore, a magnetic paint was produced in the same manner as in the above example using surfactants H, I, J and K according to the present invention as the surfactants in the above example, and the same procedure as in the above example was carried out. When the magnetic properties were measured, almost the same tendency as in the case of Surfactant G was observed in each case. r-Fe ₂ O ₃ powder...100 parts by weight PVC-vinyl acetate copolymer...15 Dioctyl phthalate...4 Surfactant of the present invention or comparative surfactant...1 or 4 Toluene...122 〃 Methyl ethyl ketone...110 〃 The above magnetic paint was applied to a polyester film in a conventional manner, oriented and dried to obtain a magnetic recording medium on which a magnetic coating film with a thickness of about 8 μm was formed. The magnetic properties of these were measured in the same manner as in Example 1, and the results shown in Table 4 were obtained.

[Table] Example 5 A magnetic recording medium was obtained in the same manner as in Example 1 except that the production of the magnetic paint was changed as shown below, and when the magnetic properties of this medium were measured, the results were almost the same as in Example 1. I got it. r-Fe ₂ O ₃ powder treated with 1% surfactant B according to the present invention...100 parts by weight PVC-vinyl acetate copolymer...17.5 Polyurethane resin...7.5 Methyl ethyl ketone...100 Cyclohexanone...100

Claims (1)

[Claims] 1. General formula (However, R is a nonylphenyl group, an octylphenyl group, an oleyl group, or an alkyl group having 12 to 16 carbon atoms, R' is an alkylene group, and (R'O) _o is
A mixed polyoxyalkylene group of C ₂ H ₄ O and C ₃ H ₆ O groups, with 2 to 7 moles of C ₂ H ₄ O groups and 2 moles of C ₃ H ₆ O groups.
It is a mixed polyoxyalkylene group containing ~7 mol and in which the C ₂ H ₄ O group and the C ₃ H ₆ O group are randomly addition-polymerized. phosphoric acid monoester compound represented by (n is an integer from 4 to 14 and represents the number of added moles),
A magnetic material characterized by containing at least one of a phosphoric acid diester compound and a derivative thereof. 2 General formula (However, R is a nonylphenyl group, an octylphenyl group, an oleyl group, or an alkyl group having 12 to 16 carbon atoms, R' is an alkylene group, and (R'O) _o is
A mixed polyoxyalkylene group of C ₂ H ₄ O and C ₃ H ₆ O groups, containing 2 to 7 moles of C ₂ H ₄ O groups, 2 to 7 moles of C 3 H 6 O groups, and containing C ₂ H 4 O groups and 2 to 7 moles of C ₃ H ₆ O groups. The H ₄ O group and the C ₃ H ₆ O group are mixed polyoxyalkylene groups that are randomly addition-polymerized. (n is an integer from 4 to 14 and represents the number of moles added) A powdered magnetic material is immersed in an aqueous liquid containing at least one of a phosphoric acid monoester compound, a phosphoric acid diester compound, and their derivatives shown in , a method for producing a magnetic material, characterized by drying. 3 General formula (However, R is a nonylphenyl group, an octylphenyl group, an oleyl group, or an alkyl group having 12 to 16 carbon atoms, R' is an alkylene group, and (R'O) _o is
A mixed polyoxyalkylene group of C ₂ H ₄ O and C ₃ H ₆ O groups, with 2 to 7 moles of C ₂ H ₄ O groups and 2 moles of C ₃ H ₆ O groups.
It is a mixed polyoxyalkylene group containing ~7 mol and in which the C ₂ H ₄ O group and the C ₃ H ₆ O group are randomly addition-polymerized. (n is an integer from 4 to 14 and represents the number of moles added) Method of manufacturing the material.