JPH0594046A - Production of magnetic particle and production of toner - Google Patents

Abstract

PURPOSE:To obtain a magnetic toner excellent in moisture resistance in which the use amt. of a suspension stabilizer is reduced. CONSTITUTION:The production method of magnetic particles and toner includes the following processes. A process to emulsify and granulate a resin compsn. containing a magnetic powder, radial polymerizable monomers, polymn. initiator and oil-soluble condensation polymn. material in a water solvent, a process to and a water-soluble condensation polymn. material which can react with the oil-soluble condensation polymn. material to the water solvent to effect the reaction, and a process to polymerize the radial polymerizable monomers. The polymn. initiator used is expressed by the formula, R<1>-N=N-R<2>. In the formula, R<1> and R<2> are different substituents from each other. By using this polymn. initiator, no nitrogen gas is produced during polymn. of monomers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing binder type magnetic particles obtained by a suspension polymerization method and a method for producing a toner. More specifically, the present invention relates to a binder type carrier used in an electrostatic charge developing developer. And a method for producing a toner for electrostatic charge development.

[0002]

2. Description of the Related Art As a method for producing this type of binder type magnetic particles, for example, JP-A-61-212058 discloses a radical polymerizable monomer such as vinyl acetate, a polymerization disclosure agent, magnetic powder, diisocyanate and the like. A resin composition containing an oil-soluble polycondensation material and a suspension stabilizer is subjected to suspension granulation in an aqueous medium, and then a water-soluble polycondensation material capable of reacting with the oil-soluble polycondensation material such as a diamine is prepared. A method has been proposed in which, by adding it to an aqueous medium, it reacts with an oil-soluble polycondensation material to form a film on the surface of droplets, and then the above polymerizable monomer is polymerized.

In such a method, since a film is formed on the surface of the droplets suspended in the aqueous medium in the step before the polymerization of the polymerizable monomer, the droplets are prevented from coagulating with each other, Therefore, it is said that the amount of the suspension stabilizer used is small and magnetic particles having excellent moisture resistance can be obtained.

However, the above method has the following drawbacks. Therefore, theoretically, magnetic particles having excellent moisture resistance can be obtained as shown in the publication, but such magnetic particles are actually used. You can't get it.

That is, the polymerization initiator used above (V-65 is used in the examples) is an azo type, which is safer than the peroxide polymerization initiator. It is used because of its excellent properties, but when the polymerizable monomer is polymerized using this azo-based polymerization initiator as described above, nitrogen, which is a decomposition product of the polymerization initiator, is used. There is a drawback in that the film formed on the surface of the droplet may be expanded and destroyed due to the generation of gas in the droplet.

Further, even when a toner is manufactured by the method according to the above publication, the same drawbacks as those described above are observed when an azo type polymerization initiator is used as the polymerization initiator, and JP-A-59-59. As disclosed in Japanese Patent Laid-Open No. 162562/162, when a peroxide-based polymerization initiator is intentionally used, the radicals generated at the time of polymerization in carbon black as a toner component disappear, so that the polymerization reaction is completed. There was a drawback that it didn't.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to reduce the amount of suspension stabilizer used and to provide excellent moisture resistance. It is an object of the present invention to provide a method for producing magnetic particles and a method for producing toner, in which magnetic particles and toner are obtained and the coating film of the droplets thereof is not destroyed during the polymerization of the polymerizable monomer.

[0008]

The method for producing magnetic particles of the present invention comprises a magnetic powder, a radical-polymerizable monomer, an asymmetric azo-based polymerization initiator represented by the following general formula (1), and an oil-soluble one. A step of suspending and granulating a resin composition containing a polycondensation material in an aqueous medium, wherein the water-soluble polycondensation material capable of reacting with the oil-soluble polycondensation material is added to the aqueous medium. It includes a step of reacting with a soluble polycondensation material, and a step of polymerizing a radical-polymerizable monomer, whereby the above object is achieved.

R ¹ -N = N-R ² (1) In the formula, R ¹ and R ² represent different substituents.

Further, the method for producing a toner of the present invention is a resin composition containing carbon black, a radical-polymerizable monomer, an azo polymerization initiator represented by the above formula (1), and an oil-soluble polycondensation material. Suspension granulation of the product in an aqueous medium, a water-soluble polycondensation material capable of reacting with the oil-soluble polycondensation material is added to the aqueous medium to react with the oil-soluble polycondensation material And a step of polymerizing a radically polymerizable monomer, whereby the above object is achieved.

Examples of the radically polymerizable monomer contained in the resin composition used in the method for producing magnetic particles and the method for producing toner of the present invention include styrenes such as styrene, chlorostyrene and vinylstyrene; ethylene. , Mono-olefins such as propylene, butylene, isobutylene; vinyl esters such as vinyl acetate, propylene vinyl, vinyl benzoate, vinyl butyrate; methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, acrylic acid Esters of α-methylene aliphatic monocarboxylic acids such as phenyl, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether. Vinyl methyl ketone, vinyl hexyl ketone, and the like ketones such as vinyl isopropenyl ketone. These compounds may be used alone or in combination of two or more.

The above resin composition may contain a known thermoplastic resin in addition to the above monomers. For example, polystyrene, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer,
Examples thereof include styrene-maleic anhydride ester copolymer, polyethylene, polypropylene and the like. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin and waxes can be used. These compounds may be used alone or in combination of two or more.

When magnetic particles such as carriers are produced according to the method of the present invention, the resin content is preferably 20 to 80% by weight based on the magnetic particles.

The general formula (1) contained in the above resin composition
In the asymmetric azo polymerization initiator represented by the formula,
R ¹ and R ² may each be a substituent except hydrogen, for example, an alkyl group which may have another substituent (eg, cyan, etc.), a phenyl group which may have another substituent. ,
Examples thereof include a cycloalkyl group which may have another substituent and a carbamoyl group. Specifically, the following equation (2)
1-[(1-cyano-1-methylethyl) azo] formamide represented by the formula and 2-phenylazo-4-methoxy-formula represented by the formula (3)
Examples include 2,4-dimethylvaleronitrile.

[0015]

[Chemical 1]

[0016]

[Chemical 2]

The oil-soluble polycondensation material contained in the resin composition is an oil-soluble compound having two or more functional groups (for example, isocyanate group, diglycidyl group, carboxyl group, amino group, hydroxyl group, etc.). Preferably used are diisocyanates, epoxy compounds and the like.

As the water-soluble polycondensation material capable of reacting with the oil-soluble polycondensation material, a water-soluble compound having two or more functional groups (eg, amino group, carboxyl group, hydroxyl group, etc.) is preferable. Used are diamine, polyhydric alcohol and the like.

In the method for producing magnetic particles, the magnetic powder contained in the resin composition may be any substance that is extremely strongly magnetized in that direction by a magnetic field.
Metals such as iron, cobalt, nickel; alloys or compounds containing ferromagnetism elements such as ferrite, magnetite, hematite, etc., such as iron, cobalt, nickel; An alloy exhibiting ferromagnetism, for example, manganese-
Heusler alloys containing manganese such as copper-aluminum or manganese-copper-tin and copper are listed.
These compounds may be used alone or in combination of two or more.

The content of the above magnetic powder is preferably 20 to 80% by weight based on the magnetic particles. When the content of the magnetic powder is less than 20% by weight, for example, when magnetic particles are used as a carrier, the magnetic attraction force of the developing sleeve is weakened, the carrier adheres to the photoconductor, and the developer spills from the developing machine. Occurs. On the other hand, when the content of the magnetic powder exceeds 80% by weight, the binding effect of the resin cannot be sufficiently obtained and the carrier is cracked. In addition, the dispersion of the contained particles such as magnetic powder becomes poor, and a homogeneous resin carrier cannot be obtained. The particle size of the magnetic powder is preferably 15 μm or less.

In the method for producing a toner, the resin composition contains carbon black as a colorant, and may further contain other colorants, charge control agents, offset preventing agents and other additives as required.

Examples of the colorant include aniline blue, chalco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green, lamp black and rose bengal. These colorants may be used alone or 2
You may use together 1 or more types.

The charge control agent is a charge control agent known per se in order to adjust the charging property of the toner, for example, naphthenic acid, salicylic acid, octylic acid, sulfonic acid, higher fatty acid, manganese of resin acid, iron. A metal soap which is a metal salt of cobalt, nickel, lead, zinc, cerium, calcium, sodium or the like; a metal-containing azo dye; a pyrimidine compound; a metal chelate of alkylsalicylic acid is used.

Examples of the offset preventing agent include, for example,
Various waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and paraffin wax; olefin polymers having 4 or more carbon atoms; fatty acid amide; silicone oil and the like.

Also in the production of magnetic particles, the above resin composition may contain these additives.

In order to produce magnetic particles, first, a resin composition containing the magnetic powder, a radical-polymerizable monomer, an asymmetric azo polymerization initiator, and an oil-soluble polycondensation material is suspended in an aqueous medium. Granulate. The particle diameter of the resin composition droplets formed in this step is preferably 30 to 150 μm. Next, a water-soluble polycondensation material is added to the aqueous medium in which the large number of droplets have been formed, and reacted with the oil-soluble polycondensation material. The aqueous medium is usually water to which a small amount of suspension stabilizer is added, and alcohol or the like may be added. As the suspension stabilizer, known ones such as a surfactant such as sodium dodecylbenzenesulfonate and a water-soluble polymer such as polyvinyl alcohol are used.

By reacting the oil-soluble polycondensation material and the water-soluble polycondensation material contained in the resin composition, a film which is a polycondensation product is formed on the surface of the droplet. This step is performed at a temperature not higher than the decomposition temperature of the polymerization initiator contained in the resin composition, and is performed at a relatively low temperature. Next, the temperature of the aqueous medium containing the droplets is raised to decompose the polymerization initiator to polymerize the radical polymerizable monomer. The temperature in this process is 50 ℃
-100 degreeC is preferable. Then, the polymer is filtered and washed with water to obtain magnetic particles.

When the toner is manufactured, it can be carried out in the same manner as the above-mentioned magnetic particles except that carbon black is used. Toner particle size is 3 ~ 15μm
Is preferred.

[0029]

[Function] The reaction between the oil-soluble polycondensation material present in the droplets formed by suspension granulation and the water-soluble polycondensation material added to the aqueous medium is caused by the radical polymerization present in the droplets. By conducting a condensation reaction prior to the reaction of the volatile monomer,
A coating is formed on the surface of the droplets, thus preventing the droplets from agglomerating with each other.

After that, when the polymerizable monomer begins to polymerize with the azo-based polymerization initiator, nitrogen gas is not generated for the following reason, so that the above-mentioned coating is not destroyed and spherical magnetic Particles or toners are obtained. That is, in the azo type polymerization initiator, R
^{Since 1} and R ² are different, the bond energies of R ¹ -N and NR ² are different. Therefore, N = N part is R
^Since it remains in the droplet in a state of being bonded to either one side of ¹ or R ² , it is not generated as nitrogen gas during the polymerization.

[0031]

EXAMPLES The present invention will be specifically described below based on examples.

Example 1 A resin composition was obtained by mixing the following carrier materials.

Next, the above resin composition was added to a dispersion obtained by adding 0.8 parts by weight of sodium dodecylbenzenesulfonate to 600 parts by weight of distilled water, and using TK Homomixer (manufactured by Tokushu Kika Kogyo) for high viscosity. The mixture was stirred for 12 minutes at a rotation speed of 6000 rpm using a mixer with modified legs.

The obtained suspension was transferred to a separable flask, and under a nitrogen atmosphere, the temperature was 40 ° C. and the rotation speed was 250 rp.
While stirring at m, an aqueous solution prepared by dissolving 10 parts by weight of xylenediamine in 30 parts by weight of distilled water was added dropwise over 30 minutes.

Then, the temperature was raised to 85 ° C. and the reaction was carried out for 12 hours to complete the polymerization. After the completion of the polymerization reaction, the polymer was filtered, washed with water and dried to obtain a carrier.

[Carrier Material] Styrene 70 parts by weight Butyl methacrylate 20 parts by weight Divinylbenzene 2 parts by weight Diethylene glycol glycol methacrylate 8 parts by weight Iron trioxide (BL-100 made by Titanium Industry) 100 parts by weight Iron trioxide (BL-200) 100 parts by weight Titanate coupling agent (KR-TTS manufactured by Ajinomoto) 0.5 parts by weight Diphenylmethane-4,4-diisocyanate 10 parts by weight 1-[(1-cyano-1-methyl-ethyl) azo] formamid 5 parts by weight of Example 2 In Example 1, 2-phenylazo-4 was used instead of 1-[(1-cyano-1-methyl-ethyl) azo "] formamide.
A carrier was obtained in the same manner as in Example 1 except that -methoxy-2,4-dimethylvaleronitrile was used.

Comparative Example 1 In Example 1, 2,2'-azobis- was used instead of 1-[(1-cyano-1-methyl-ethyl) azo "] formamide.
Other than using (2,4-dimethylvaleronitrile),
A carrier was obtained by the same operation as in Example 1.

In Comparative Example 1, nitrogen gas was generated from the droplets as the polymerization reaction proceeded after the temperature was raised, and the film expanded,
The coating cracked. The obtained polymer was made into a carrier by the same procedure as in the example.

[Evaluation Method] Each of the above-obtained carriers was mixed with a toner for DC-2585 (manufactured by Mita Kogyo Co., Ltd.) to prepare a developer having a toner / developer ratio of 8%.
C-2585 (manufactured by Mita Kogyo Co., Ltd.) was used to measure the amount of blow-off charge at the initial stage of printing at room temperature and normal humidity, and the formed image was observed to blow-off charge after printing 10,000 sheets at normal temperature and normal humidity. The amount was measured and the image was observed. The results are shown in Table 1.

[0040]

[Table 1]

Example 3 A toner composition was obtained by mixing the following toner materials.

Next, the above toner composition was added to a dispersion obtained by dissolving 1.0 part by weight of sodium dodecylbenzenesulfonate in 600 parts by weight of distilled water, and using a TK homomixer (made by Tokushu Kika Kogyo). 12 at 11,000 rpm
Stir for minutes.

The obtained suspension was transferred to a separable flask, and under a nitrogen atmosphere, the temperature was 40 ° C. and the rotation speed was 120 rp.
While stirring at m, an aqueous solution prepared by dissolving 10 parts by weight of hexamethylenediamine in 30 parts by weight of distilled water was added dropwise over 30 minutes.

Then, the temperature was raised to 85 ° C. and the reaction was carried out for 12 hours to complete the polymerization. After the completion of the polymerization reaction, the polymer was filtered, washed with water and dried to obtain a toner. The obtained toner was mixed with 0.2% by weight of hydrophobic silica fine powder and surface-treated.

[Toner material] Styrene 82 parts by weight 2-Ethylhexyl methacrylate 18 parts by weight Divinylbenzene 0.2 parts by weight Diethylene glycol methacrylate 1.5 parts by weight Carbon black 5 parts by weight Charge control dye 0.8 parts by weight Charge controllability Resin 2 parts by weight Terephthalic acid chloride 20 parts by weight 1-[(1-cyano-1-methyl-ethyl) azo] formamide 5 parts by weight Example 4 In Example 3, 1-[(1-cyano-1-methyl- 2-phenylazo-4 instead of ethyl) azo "] formamide
A toner was obtained in the same manner as in Example 2, except that -methoxy-2,4-dimethylvaleronitrile was used. The particle size of the droplets of the monomer after suspension granulation was 10.8 μm.

The obtained toner was mixed with 0.2% by weight of a fine powder of hydrophobic silica and surface-treated.

Comparative Example 2 In Example 3, instead of 1-[(1-cyano-1-methyl-ethyl) azo "] formamide, 2,2'-azobis-
Other than using (2,4-dimethylvaleronitrile),
Toner was obtained in the same manner as in Example 3. The particle size of the droplets of the monomer after suspension granulation was 10.6 μm. Got a career.

In Comparative Example 2, nitrogen gas was generated from the droplets as the polymerization reaction proceeded after the temperature was raised, and the coating film expanded,
The coating cracked. The obtained toner was mixed with 0.2% by weight of hydrophobic silica fine powder and surface-treated.

[Evaluation Method] Next, each of the toners obtained above was mixed with a carrier for DC-2585 (manufactured by Mita Kogyo Co., Ltd.) to prepare a developer having a toner / developer ratio of 4%. Machine DC-2585 (manufactured by Mita Kogyo Co., Ltd.) is used to measure the amount of blow-off charge at the beginning of printing at room temperature and normal humidity, observe the formed image, and blow-off after printing 10,000 sheets at room temperature and normal humidity. The amount of charge was measured and the image was observed. The results are shown in Table 2.

[0050]

[Table 2]

[0051]

According to the present invention, the amount of suspension stabilizer used can be reduced to obtain magnetic particles and toner having excellent moisture resistance, and in addition, a coating film on the surface of droplets formed during polymerization. Fluidity, surface hardness,
Magnetic particles and toner having excellent chargeability and moisture resistance can be obtained. Therefore, it is possible to obtain a developer having improved chargeability, rising of charge, durability, and environment resistance.

Claims (2)

[Claims] 1. A magnetic powder, a radical-polymerizable monomer, an asymmetric azo polymerization initiator represented by the following general formula (1),
And a step of suspending and granulating a resin composition containing an oil-soluble polycondensation material in an aqueous medium, and adding a water-soluble polycondensation material capable of reacting with the oil-soluble polycondensation material to the aqueous medium And a step of reacting with the oil-soluble polycondensation material, and a step of polymerizing a radical-polymerizable monomer. R ¹ -N = N-R ² (1) In the formula, R ¹ and R ² represent different substituents. 2. A step of suspending and granulating a resin composition containing carbon black, a radically polymerizable monomer, the azo polymerization initiator according to claim 1, and an oil-soluble polycondensation material in an aqueous medium, In the aqueous medium, a step of adding a water-soluble polycondensation material capable of reacting with the oil-soluble polycondensation material to react with the oil-soluble polycondensation material, and a step of polymerizing a radical-polymerizable monomer, A method of making a toner that includes.