JP2515418B2 - Polymerizable magnetic fluid - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to polymerizable magnetic fluids.

Conventional technology Magnetic fluids in which magnetic particles are dispersed in a hydrocarbon solvent such as kerosene have been known for a long time (eg SS
papell: US pat. No 3215572 (1965) etc.). In these techniques, a long chain fatty acid or the like is used as a dispersant, but the dispersant described therein cannot disperse the magnetic particles in the polymerizable monomers, and even if temporary dispersion can be achieved. It is impossible to obtain a polymer in which particles are rapidly aggregated during the polymerization of the polymerizable monomer and the magnetic particles are uniformly dispersed.

A technique for dispersing magnetic particles in a polymer is described in JP-A-1-289883, but since it is a kneading method, it is extremely difficult to uniformly disperse ultrafine magnetic particles.

The Adhesion Society of Japan Vol.26, No.2 (1990) discloses a magnetic monomer obtained by reacting γ-Fe ₂ O ₃ with a silanol group by a chemical bond. It is not a decentralized technique, nor does it provide such teaching. It only shows a very specific magnetic compound.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to provide a polymerizable magnetic fluid. The polymerizable magnetic fluid has extremely high fluidity and can be freely moved to a desired portion by applying a magnetic force. It is possible to bond or fill hollow portions, fine pores, cracks, voids, etc. that could not be filled or bonded with an adhesive. It is also useful as a raw material for magnetic tape paints, magnetic head adhesives, plastic magnets, magnetic shield materials, magnetic paints, magnetic toners, magnetic inks, magnetic films or sheets, magnetic plastic particles, and the like. The present invention provides a technique of uniformly dispersing magnetic particles in a polymerizable monomer medium, which has been impossible in the past, to obtain a polymerizable magnetic fluid that does not cause precipitation separation of particles even during polymerization.

Means for Solving the Problems The present invention relates to a polymerizable magnetic fluid in which magnetic particles treated with a dispersant having an anionic and / or cationic residue and a polymerizable residue are dispersed in a polymerizable monomer medium.

The magnetic particles used in the present invention may be magnetic particles used in a conventional non-polymerizable magnetic fluid or magnetic particles produced by a method similar to the magnetic particles, and the particle size of the magnetic particles has stability and It may be selected according to the purpose of use. General paints, adhesives, fillers, magnetic inks,
It is preferable to use ultrafine particles of about 50 to 500Å for magnetic films, etc., and for magnetic tapes, etc., a particle size that forms a permanent magnet is required.For example, Fe-Co particles of about 100 to 500Å are suitable . Also, in the case of paints and adhesives that need to be stored for a relatively long period of time, it is desirable to use ultrafine particles of about 50 to 200Å from the viewpoint of long-term stability. Such ultrafine particles are preferably prepared at the time of producing the magnetic fluid, and the method thereof is described in detail in, for example, JP-A-58-89802.

Examples of magnetic particles include metal oxides such as magnetite (FeO · Fe ₂ O ₃ ), γ-hematite (γ-Fe ₂ O ₃ ), simple ferrite (MnO · Fe ₂ O ₃ , BaO · Fe ₂ O ₃ , CoO).・ Fe ₂ O ₃ , Ni
O ・ Fe ₂ O ₃ , CuO ・ Fe ₂ O ₃ , ZnO ・ Fe ₂ O _3, etc.), composite ferrite (MnO _(n)・ ZnO _(1-n)・ Fe ₂ O ₃ , ZnO _(n)・ FeO _{( 1-n)}・ Fe ₂
O ₃ , MnO _(n) , FeO _(1-n) , Fe ₂ O ₃ , MnO _(n) , CoO _(1-n) , Fe ₂
O ₃ , NiO _(n) , ZnO _(1-n) , Fe ₂ O ₃ , CoO _(n) , FeO _(1-n) , Fe ₂
O ₃ etc.); metal nitrides such as Fe _(3-4) N etc .; metals,
For example, Fe, Co, Ni, Fe-Ni, Fe-Co and the like are exemplified.

The magnetic particles are treated with a dispersant having an anionic and / or cationic residue and a polymerizable residue.

The anion and / or cationic residue means a phosphate group, a carboxyl group, a sulfonic acid group, a sulfate ester group,
A betaine-type amphoteric group and the like are preferable, and a phosphate group, a carboxyl group, and a betaine-type amphoteric group are particularly preferable.

The polymerizable residue, for example, a group having a polymerizable double bond,
Acrylic compounds, vinyl compounds and the like, represented by groups such as acryl, methacryl, itaconyl, maleyl and cinnamyl.

These polymerizable residue and anion and / or cationic residue are mediated by polyalkylene glycol, polylactone diol and other polyols such as ethylene glycol, propylene glycol, glycerin, polyglycerin and trimethylolpropane. It may be bonded, and particularly good results are obtained with a dispersant having polyalkylene glycol, polylactone diol, or the like.

Specific examples of the dispersant include: In the formula, x = 2, y = 1; x = 1, y = 2 [In the formula, n is an integer, particularly 1 to 20; R is hydrogen, an alkyl group; R
₁ is an alkylene group; R ₂ , R ₃ and R ₄ are alkyl groups; A is an oxyalkylene group (may be a mixed type), lactone diol, a lactone ring-opening residue; B is a lactone ring-opening residue, etc. [Shown] and the like are exemplified.

The polymerizable monomer medium in which the magnetic particles are dispersed is a monofunctional monomer such as a carboxyl group-containing monomer such as acrylic acid or methacrylic acid; alkyl acrylate or methacrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, n- Butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth)
Acrylate, lauryl, stearyl, etc .; Hydroxyl group-containing acrylate or methacrylate, such as 2-hydroxyethyl, 2-hydroxypropyl, ω-hydroxyhexanoyloxyethyl, etc .; Alkoxy-based acrylate or methacrylate, such as 2-methoxyethyl, 2- Ethoxyethyl,
2-butoxyethyl, 2-phenoxyethyl, nonylphenoxyethyl, nonylphenoxypropyl, ethylcarbitol, tetrahydrofurfuryl, etc .; glycol-based acrylates or methacrylates such as polyethylene glycol, polypropylene glycol, methoxypolyethylene, methyltriglycol, phenoxypolyethylene. Glycol, etc. Polymerizable amides, such as acrylic acid amide, methacrylic acid amide, Nn-butoxymethylmethacrylamide, N, N'-methylenebisacrylamide, etc. Nitrogen-containing alkyl acrylates or methacrylates, such as dimethylaminoethyl, diethylamino Ethyl, etc .; Aromatic or cycloaliphatic acrylates or methacrylates such as benzyl, cyclohexyl, phenyl Nylcarbitol, isobornyl, dicyclopentenyl, etc .; Vinyl derivatives such as ethylene, propylene, butadiene, isoprene, styrene, N-methylstyrene,
Vinyltoluene, vinyl chloride, vinylidene chloride, vinyl acetate, acrylonitrile, acrylaldehyde, N-vinyl-pyrrolidone, vinyl propionate, etc .; isocyanate type; phosphate type; glycerine type;
Others; and polyfunctional monomers such as diol acrylates or methacrylates such as 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth)
Acrylate, etc .; Glycol-based acrylates or methacrylates such as ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, PEG # 200 di (meth) acrylate, PEG # 400 di (meth) acrylate,
PEG # 600 di (meth) acrylate, neopentyl glycol di (meth) acrylate, α, ω-diacryloyl- (bisethylene glycol) phthalate, hydroxypivalic acid neopentyl glycol ester diacrylate, etc .; trimethylol or dimethylol acrylate Alternatively, methacrylates such as trimethylolpropane tri (meth) acrylate, dimethylolethanedi (meth) acrylate, trimethylolethanetri (meth) acrylate, α, ω-tetraacryloyl- (bistrimethylolpropane) -tetrahydrophthalate, etc .; erythritol. -Based acrylates or methacrylates such as pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, diester Pentaerythritol hexa (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, α, ω-hexaacryloyl-
(Bispentaerythritol) -adipate, dipentaerythritol hexa (meth) acrylate, and mixtures thereof; Bisphenol A or bisphenol S acrylates or methacrylates, such as bisphenol A di (meth) acrylate, bisphenol S di (meth) acrylate Etc .; ethylene oxide, propylene oxide or lactone addition acrylates or methacrylates; for example, bisphenol A ethylene oxide addition di (meth) acrylate, trimethylolpropane propylene oxide addition tri (meth) acrylate, bisphenol S ethylene oxide addition di (meth) acrylate, glycerin propylene Oxide-added tri (meth) acrylate,
Hydroxypivalic acid neopentyl glycol ester-caprolactone addition di (meth) acrylate, etc .; Isocyanate-based acrylates or methacrylates such as bis (acryloyloxyethyl) .hydroxyethyl isocyanate, tris (acryloyloxyethyl) isocyanate, tris (methacryloyl) Roxyethyl) isocyanate, etc .; vinyl group derivatives, such as divinylbenzene; and others, such as triallyl trimellitate, diallyl chlorendate, N-phenylmaleimide, and phosphates.

Two or more kinds of these polymerizable monomer media may be mixed and used. If the boiling point is too low, it is necessary to carry out the dispersion treatment in a closed system. A part of the polymerizable dispersant may be mixed with the polymerizable monomer.

Examples of particularly typical polymerizable monomers are styrene, methyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, vinyl acetate.

The magnetic particles may be previously treated with a dispersant having an anionic and / or cationic residue polymerizable residue and dispersed in a polymerizable monomer medium, or in a medium containing the dispersant and the polymerizable monomer medium. May be added. The former can generally obtain a uniform and stable magnetic fluid.

The amount of the dispersant used for treating the magnetic particles is usually 5 to 100 parts by weight, more preferably 20 to 70 parts by weight, based on 100 parts by weight of the magnetic particles. The content of magnetic particles in the magnetic fluid is 1 to 70% by weight, more preferably 2 to 60% by weight.

A typical method for producing a magnetic fluid is to gradually add an alkali such as NaOH to an aqueous solution of a water-soluble metal salt of a magnetic substance to form an oxide precipitate, which is washed with water to remove a by-product salt. If necessary, water is replaced with a solvent such as alcohol to prepare a solvent type slurry, and then a dispersant is added thereto and mixed sufficiently. A polymerizable monomer medium is further added to this, and a solvent such as alcohol is distilled off to obtain a magnetic fluid.

This magnetic fluid may contain a polymerization inhibitor, a plasticizer, a cross-linking agent, a coloring material, a fragrance, etc., if necessary. Further, in order to further improve the dispersibility of the magnetic particles, a surfactant may be used together.

The magnetic fluid of the present invention can be used for various purposes.
For example, adhesive, adhesive, magnetic shield material, magnetic toner, magnetic head adhesive, plastic magnet, magnetic paint,
It can be used for magnetic inks, fillers, magnetic tapes, magnetic films, magnetic fibers, pharmaceutical carriers and the like.

When used as an adhesive, it is advantageous because the adhesive can be guided by a magnetic force to a predetermined portion such as a narrow or deep crack that does not penetrate with a normal adhesive or a structure having a complicated crack or damage inside.

When it is used as an adhesive, for example, it can be used as a wallpaper, and a calendar or the like can be fastened with a magnet without using a push pin or the like.

When it is used as a magnetic head adhesive, the conventional mirror surface processing for reducing the surface roughness of the ferrite bonding surface is unnecessary, and the processing cost and man-hours can be reduced.

The polymerizable magnetic fluid of the present invention can be molded into a tile shape to be used as a ferrite electromagnetic wave absorber and as a floor or wall material in a computer shielded room.

It is also used as a filler to prevent magnetic flux leakage by filling and hardening the magnetic leakage portion.

By using the magnetic fluid of the present invention, a plastic magnet having uniform magnetism can be manufactured.

When used as a magnetic toner, the toner can be produced by simply mechanically dispersing and polymerizing in water without using a conventional manufacturing method such as pulverization or spray drying, and a toner having a uniform particle size and shape can be obtained.

When used as a magnetic paint, magnetic shielding can be easily performed.

The magnetic ink enables printing of a pattern corresponding to the magnetic pattern.

When used as a magnetic tape, it is possible to obtain a magnetic tape in which the binder is more uniformly dispersed than the conventional one.

When the affected part is in a difficult place to inject in the body, by blending the medicinal component in the magnetic fluid of the present invention, injected near the affected part, by transferring it to the affected part by magnetic force and polymerizing,
The affected part and the medicine can be contacted for a long period of time.

 Hereinafter, examples will be described.

Example 1 NaOH (granular) 835 g water 3420 in a conventional reactor with stirrer
Dissolve in ml. Apart from _{MnSO 4 · 4~5H 2 O396g, ZnSO} 4 · 7H 2 O
118 g and Fe ₂ (SO ₄ ) ₃ (active ingredient 41%) 2053 g in water 246
Dissolve in 0 ml to prepare a salt solution.

The salt solution is added to the NaOH solution by dropwise stirring for 15 to 20 minutes while maintaining the reaction temperature at 40 ° C or lower. 80 ~ reaction product
Heat to 85 ° C and age for about 10 minutes. The pH of the reaction system becomes about 12. After cooling, in order to remove the by-product salt in the reaction product, washing with water is repeated by decantation and filtration to remove the by-product salt.

Further, the water in the slurry is replaced with isopropyl alcohol by decantation and filtration using isopropyl alcohol.

163.8 g (purity) of isopropyl alcohol slurry of Mn / Zn / ferrite was charged into another ordinary reactor with a stirrer, and acid phosphooxypolyoxypropylene glycol monomethacrylate (trade name Phosmer PP, average molecular weight 430 to 467, Unichemical Co., Ltd.) 65.8 g above Mn
・ Mixed into Zn / ferrite slurry, 4-6hr at room temperature
While continuing aeration, stir to adsorb.

A solution of 0.05 g of hydroxymonomethyl ether, a polymerization inhibitor, dissolved in 98 g of n-butyl methacrylate was added to the suspension of the ferromagnetic ultrafine particles, and the mixture was heated to 75 to 82 ° C.
Distill off isopropyl alcohol while continuing aeration.

The obtained n-butyl methacrylate-based magnetic fluid is centrifuged (12500 g × 5 minutes) to obtain a magnetic fluid.

The physical properties of the product are as follows: Viscosity (20 ℃) 30-50cps Specific gravity (20 ℃) 1.30-1.40 Ash (%) 42.0 Magnetizing force (7040Oe) 400-440G Polymerization initiator benzoyl peroxide in 43g of the above monomer-based magnetic fluid (Nyper B, manufactured by NOF CORPORATION) 0.
Dissolving 3g, after turning N ₂ purge to a plastic container, 75 ° C.
As a result, polymerization was carried out for 2 to 3 hours while continuously heating. As a result, a resin composition of uniformly dispersed Mn.Zn.ferrite ultrafine particles was obtained.

Example 2 692 g of NaOH (granular) is dissolved in 3200 ml of water. Separately FeSO ₄
・ 7H ₂ O (industrial 95%) 685g and FeCl ₃ (effective 39%) 162
An iron salt solution is prepared by dissolving 6 g in about 2300 ml of water.

The iron salt solution was added dropwise to the NaOH solution over 30 minutes while maintaining the reaction temperature at 27 to 40 ° C. The reaction product is heated to 60 ° C. and aged for about 30 minutes. The pH of the reaction system becomes about 12.

After cooling, washing with water is repeated by decantation and filtration to remove by-product salts in the reaction product. Further, the water in the slurry is replaced with isopropyl alcohol by using isopropyl alcohol.

147 g of isopropyl alcohol slurry of the above magnetite in pure content was mixed with 47.3 g of acid phosphooxypolyoxyethylene glycol monomethacrylate (trade name Phosmer PE, average molecular weight 341 to 383, Unichemical Co., Ltd.) into the above magnetite slurry. At room temperature, agitate and adsorb while continuing aeration for 4 to 6 hours.

A solution of 0.05 g of hydroxymonomethyl ether, a polymerization inhibitor, in 100 g of n-butyl methacrylate was added to the suspension of the magnetite ultrafine particles, and the mixture was heated to 75 to 82 ° C and isopropyl alcohol was added while continuing aeration. Distill off.

The obtained n-butyl methacrylate magnetic fluid is centrifuged (12500 g × 5 minutes) to obtain a magnetic fluid.

The physical properties of the product are as follows: Viscosity (20 ℃) 20-30cps Specific gravity (20 ℃) 1.25-1.35 Ash (%) 39-41 Magnetizing force (7040Oe) 380-420G To improve the yield of monomer-based magnetic fluid The SP value (solubility parameter) may be adjusted in order to improve the compatibility between the dispersion medium and the polymerizable dispersant, and the theoretical formula of the Small method was adopted to select the SP value adjusting agent.

Example 3 60 g of octacarbonyldicobalt Co ₂ (CO) _{8 0} , 0.08 g of sodium salt of di-2-ethylhexyl sulfosuccinate and 17 g of n-butyl methacrylate are charged and dissolved in a usual reactor equipped with a stirrer.

The octacarbonyl solution is agitated while being heated and maintained at 100 ° C., and carbon monoxide in the decomposition gas is exhausted.

When the generation of carbon monoxide has stopped, 8.3 g of acid phosphooxypolyoxypropylene glycol monomethacrylate is added to the suspension of metallic cobalt, and stirring is continued at room temperature for 4 to 5 hours.

The obtained metal cobalt n-butyl methacrylate-based magnetic fluid was centrifuged (12500 g × 5 minutes) to remove the sediment, and then a magnetic fluid was obtained.

The physical properties of the product are as follows: Viscosity (20 ° C) 20-30cps Specific gravity (20 ° C) 1.25-1.35 Ash (%) 39-41 Magnetizing force (7040Oe) 700-900G Effect of the invention By polymerization of monomer-based magnetic fluid A composite composition having high magnetic permeability, superparamagnetism, and magnetic field sensitivity can be obtained by using a resin composition of uniformly dispersed ferromagnetic ultrafine particles.

Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area // C08F 2/44 MCP C10M 125: 10 (C10M 141/10 125: 04 125: 10 125: 20 125: 04 129: 26 125: 20 135: 08 129: 26 137: 04) 135: 08 C10N 10:04 137: 04) 10:14 C10N 10:04 10:16 10:14 20:06 A 10:16 Z 20: 06 40:14 H01F 1/28 40:14 1/34 S (72) Inventor Takashi Asari 2 1-3 Shibukawa-cho, Yao City, Osaka Prefecture Matsumoto Yushi-Seiyaku Co., Ltd. (56) Reference Japanese Patent Laid-Open No. 1 -207131 (JP, A) JP-A-63-175402 (JP, A) JP-A-63-166201 (JP, A)

Claims (5)

(57) [Claims] 1. A polymerizable magnetic fluid in which magnetic particles treated with a dispersant having an anionic and / or cationic residue and a polymerizable residue are dispersed in a polymerizable monomer medium. 2. The polymerizable magnetic fluid according to claim 1, wherein the anionic and / or cationic residue is selected from a phosphate group, a carboxyl group, a sulfonic acid group, a sulfate group, and a betaine-type amphoteric group. 3. The polymerizable magnetic fluid according to claim 1, wherein the polymerizable residue of the dispersant has a polymerizable double bond. 4. The particle size of magnetic particles is 50 to 500Å and the content of magnetic particles in the magnetic fluid is 2 to 60% by weight.
The polymerizable magnetic fluid described. 5. The polymerizable magnetic fluid according to claim 1, wherein the polymerizable monomer medium is a monomer having a polymerizable double bond.