JPS6063544A - Manufacture of electrophotographic toner - Google Patents

Abstract

PURPOSE:To obtain a toner contg. a pigment and magnetic particles uniformly dispersed in the inside and having excellent developability and fixability by mixing a pigment treated with acid halide with a polymerizable memomer and polymerizing the monomer through aq. suspension polymn. to form toner particles. CONSTITUTION:A pigment or magnetic powder, such as TiO12, SiO2, Fe, Co, Ni, Fe2O3, or carbon black, is dispersed into a benzene soln. of an acid halide having >5C, treated, when needed, in the presence of a tertiary amine, such as pyridine or quinoline, at room temp. for several min, filtered, and dried to remove the solvent. These treated pigment and the magnetic powder are mixed with a monomer, and when needed, an electrostatic charge stabilizer, etc. are added, and suspension polymn. is carried out in an aq. medium dissolving a dispersion stabilizer, or a mixture of the monomer and said aic halide, and when needed, a necessary amt. of tertiary amine may be suspension-polymerized. As a result, the toner thus obtained contains the pigment and the magnetic powder uniformly in the inside of the toner particles, and it has excellent electric and magnetic characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a toner for developing electrostatic latent images in electrophotography.

As a manufacturing method for electrophotographic toner, Hiro has conventionally added pigments such as carbon black or magnetic powder to a binder resin made of natural or synthetic polymeric substances, and if necessary, dyes for charge control. , after pre-mixing in a mixer, melt-kneading in a heated mixer such as a hot roll or extruder,
Pigment in resin.

A method is used in which the dye is dispersed, cooled, coarsely pulverized, then finely pulverized, and then classified to obtain particles of the target particle size. However, this manufacturing method has complicated steps;
Moreover, in order to improve the dispersibility of the pigment in the resin, it is necessary to cross-wire at high temperature for a long time, but it is not possible to fully satisfy the uniform dispersion, and the electrical and magnetic properties are non-uniform. It is difficult to obtain a toner with good shallow soakability.

Furthermore, since the particles obtained by pulverization are amorphous, they have poor fluidity as toner particles, resulting in clogging in the developing unit.
This is undesirable because it not only causes problems but also tends to cause unevenness in the five images.

On the other hand, as a method to obtain toner directly without including the crushing process,
Pigments and dyes are added to certain polymerizable monomers and then emulsion or suspension polymerized.

A method has been proposed in which fine resin particles containing pigments, etc. are formed, and the resulting fine particles are washed and dried (for example, Japanese Patent Publication No. 56-10231, Japanese Patent Publication No. 43-10799,
(Special Publication No. 51-14895).

This method has the advantage that the toner particles produced are spherical and have excellent fluidity, the manufacturing process is simple, and the cost is low. However, in this method, pigments, especially magnetic powders with hydrophilic surface properties, have poor wettability with monomers, making it difficult to uniformly disperse them in the monomers and even in the product particles. Most of the magnetic powder adheres to the toner, which often results in toner with poor electrical properties.

Therefore, various proposals have been made for the purpose of improving the above-mentioned non-uniform dispersion of magnetic powder. For example, a method of adding a small amount of a polar solvent such as alcohol (Japanese Unexamined Patent Publication No. 56-66858), and a method of adding a silane coupling agent (Japanese Unexamined Patent Publication No. 54-847)
No. 31), titanium-based coupling agent (JP-A-57-81)
No. 271).

Furthermore, there are improved methods for copolymerizing vinyl monomers containing polar groups (JP-A-54-115236, JP-A-55-90509, JP-A-55-11218, JP-A-56-64348). However, although these methods tend to slightly improve the dispersibility of the magnetic powder in the monomer, the magnetic powder is not uniformly dispersed in the resin particles after one polymerization. Otherwise, the magnetic powder is liberated, resulting in unstable electrical and magnetic properties, and it is currently impossible to obtain a toner with excellent developability that can be put to practical use.

The present invention has been made in order to overcome the various drawbacks of toners produced by the above-mentioned pulverization method and polymerization method.
The object of the present invention is to provide a new and simple electrophotographic toner in which pigments such as magnetic powder are uniformly encapsulated in binder resin particles, and therefore have good electrical and magnetic properties and good developability. According to the present invention, the above object is achieved by aqueous polymerization of a polymerizable monomer in the presence of a pigment surface-treated with an acid halide, followed by dehydration and drying.

The treatment of the pigment with the acid halide used in the present invention during II&li production of the pigment surface-treated with the acid halide does not require particularly high temperatures, and can be performed at a temperature as low as room temperature in a short time, so it is simple. Various methods are effective as treatment methods.

For example, by dissolving the acid halide in advance in a solvent such as benzene, toluene, hexane, etc., adding and dispersing the pigment therein, and stirring at room temperature in the presence of a tertiary amine such as pyridine or quinoline as necessary. After a few minutes, the pigment is uniformly dispersed in the solvent and the treatment is complete. Thereafter, the solvent is removed by means such as air drying or vacuum drying to obtain an acid halide treated pigment. Alternatively, an acid halide is directly added to a monomerizable monomer, a pigment is dispersed therein, and the mixture is stirred at room temperature in the presence of a tertiary amine such as pyridine or quinoline if necessary.

It is also possible to add a polymerization initiator to this and then perform aqueous polymerization.1 Pigments used in the present invention include titanium oxide, silicon dioxide, zinc mide, carbon black, iron, cobalt, nickel, iron sesquioxide, Examples include magnetic powders of iron trioxide, iron manganese oxide, iron zinc oxide, and iron nickel oxide. When using magnetic powder to obtain toner particles of about 2 to 50 microns, it is desirable to use magnetic powder with a particle size of 1 micron or less. In the case of carbon black, the amount is usually 5 to 20 parts by weight (based on 100 parts by weight of the resulting polymer as a binder resin).

In addition, in the case of magnetic powder used in magnetic toner, the amount thereof is relatively large, 50 to 500 parts by weight, preferably 90 parts by weight.
~200 parts by weight.

In the present invention, when using a pigment whose surface has been previously treated with an acid halide, it is not necessarily necessary to add this pigment to the polymerization system at the initial stage of polymerization, and the total amount or amount can be added as desired. A portion of the pigment can be added during the polymerization. However, it is generally better to add the pigment before the polymerization conversion rate is 30, preferably before 20, so that the pigment can be evenly distributed in the polymer.
Desirable in terms of inclusion.

The acid halide used in the present invention has the general formula Rcox (
R is a saturated or unsaturated alkyl group or aryl group, and the number of carbon atoms in R is preferably 5 or more. Also X
is a halogen) and is not particularly limited.
are caproyl chloride, lauroyl chloride, myristoyl 6-chloride, balmitoyl chloride, stearoyl chloride, oleoyl chloride, eloidyl chloride, lyluoyl chloride, 2-bromolauroyl chloride, 2-promono(lumitoyl chloride, benzoyl chloride) , 2-furomocaproyl bromide,
Preferred substances include 2-promoenanthylbromide. The amount of the acid halide added is 5% to 10% by weight, preferably 0% to the pigment used.
．． 1 to 5% by weight. Any polymerizable monomer can be used to provide the polymer used as the binder resin in the present invention, but
Among them, vinyl monomers are typical, such as styrene monomers such as styrene, vinyltoluene, and α-methylstyrene; acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and acrylic. Acrylic or methacrylic acids such as 2-ethylhexyl methacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, acrylonitrile, acrylamide, etc. Conductor: Ethylenically unsaturated monoolefins such as ethylene, propylene and butylene; Diolefins such as butadiene, isoprene and piperylene; Vinyl halides such as vinyl chloride, vinylidene chloride and vinyl fluoride: Vinyl acetate.

Vinyl esters such as vinyl propionate; nohinyl ethers such as vinyl methyl ether and vinyl ethyl ether;
Examples include vinyl ketones such as vinyl methyl ketone and methyl isoprohenyl ketone; nitrogen-containing vinyl compounds such as 2-vinylpyridine, 4-vinylpyridine, and N-vinylpyrrolidone. These vinyl monomers may be used alone, or a plurality of monomers may be used in combination and copolymerized. In addition, along with these monomers, any arbitrary frame m
agents, such as aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene and their derivatives; diethylenically unsaturated carboxylic acid esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; divinyl compounds such as N, N-divinylaniline and divinyl ether; And compounds having three or more vinyl groups can be used alone or in combination of two or more.

The aqueous polymerization in the present invention may be either suspension polymerization or emulsion polymerization, but the particle size required for toner is generally about 2 to 50 μm, and in order to form particles with a particle size in this range, suspension polymerization is necessary. Polymerization method is preferred. However, it is difficult to form particles with a particle size within the above-mentioned range in normal suspension polymerization, so it is necessary to apply stirring shear force at the time of dispersing the monomer phase in the aqueous dispersed phase and during the subsequent progress of polymerization, and to control the size of the particles. It is necessary to control particle size during the selection of dispersion stabilizers to prevent agglomeration.

In particular, the particle size and particle size distribution of the final polymer are determined by the shearing method and shear force used when dispersing the monomer phase into the dispersed phase. It is necessary to choose appropriately.

In suspension polymerization, water-soluble polymer substances such as gelatin, starch, polyvinyl alcohol, and alkyl cellulose, as well as barium sulfate, calcium sulfate, barium carbonate, and calcium carbonate are used as dispersants to enhance the dispersion stability of particles during polymerization. .

It is necessary to use an inorganic compound powder that is poorly soluble in water, such as calcium phosphate. Further, as a surfactant, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium alkylnaphthalenesulfonate, dialkylsulfosuccinate, polyoxyethylene alkyl ether, etc. are used as necessary. These may be used alone or in combination. Furthermore, sulfuric acid)
It may also be effective to use a salting-out agent such as Uram, sodium chloride, calcium chloride, etc. in combination. Examples of the polymerization initiator include oil-soluble azo compounds such as lauryl peroxide, benzoyl peroxide, azobisisobutyronitrile, and azobisisovaleronitrile.

On the other hand, in the case of emulsion polymerization, surfactants include anionic substances such as sodium alkylbenzene sulfonate, sodium salts of higher alcohol sulfates, sodium salts or potassium salts of higher fatty acids, and nonionic substances such as polyethylene glycol ether. Pillar soaps and cationic pillar soaps such as dodecylamine hydrochloride are used.

In addition, water-soluble polymerization initiators are generally used, such as persulfates such as potassium persulfate, hydroperoxides such as cumene hydroperoxide and para-menthane hydroperoxide, and redox-based initiators. can be mentioned.

Further, as the additive for adjusting the molecular weight which has an important influence on the thermal characteristics of the resulting toner, a usual molecular weight adjusting agent can be used, and examples thereof include t-butyl mercaptan, dodecyl mercaptan and the like.

Furthermore, any dye can be used as needed to control the charge of the toner. Examples include nigrosin pace, aniline iku, calco oil blue, chrome yellow, ultramarine blue, orient oil red, phthalocyanine blue, and malachite green offsalate.

After the polymerization is completed, an electrophotographic toner is obtained by washing if desired, followed by dehydration and drying by a conventional method.

Thus, according to the method of the present invention, the powder is substantially spherical and has good fluidity, there is no trouble such as cracking in the developing unit, and pigments such as magnetic powder are uniformly encapsulated in the particles. High quality toner with excellent uniformity and good electrical and magnetic properties can be provided by a simplified manufacturing process.

Examples of the present invention will be described below, but the present invention is not limited to these. In addition, the volume resistivity value in the examples is the conductance value obtained by measuring the distance of the powder molded to a thickness of 2 ym at room temperature under a load of 10 tons of total pressure using a dielectric loss measuring machine under the conditions of j730C and frequency I KHl. This is a very well-calculated figure.

Example 1 A magnetite (111μ) 200) whose surface was washed with methanol and thoroughly dried was placed in a 2J airtight container, the atmosphere was replaced with nitrogen, and a benzene solution containing 0.5% by weight of balmitoyl chloride was added to the container (80% by weight). mouth? was added gradually and the mixture was stirred at room temperature for 10 minutes.

After several minutes of stirring, a uniform dispersion in which magnetite was well dispersed was obtained. Then remove the benzene.

Furthermore, unreacted balmitoyl chloride was washed with a large amount of benzene, and benzene was completely removed by vacuum drying to obtain 1 surface-treated magnetite.

The above-mentioned surface-treated magnetite was subjected to 1FT-R with untreated magnetite, and as a result of analysis by difference spectroscopy, absorption of carbonyl ester groups was detected. It was confirmed that fatty acids were chemically bonded to the simagnetite surface by the He removal/reaction.

Next, 70 parts by weight of styrene, 50 parts by weight of butyl methacrylate, 100 parts by weight of valmitoyl chloride-treated magnetite prepared above, and 5 parts by weight of nigromine were mixed at room temperature, and the mixture was further dispersed with stirring for 5 hours until it became viscous. A uniform dispersion liquid was obtained. Thereafter, 2 parts by weight of azobisinbutyronitrile and 2 parts by weight of t-butyl mercaptan were dissolved in this to prepare a dispersion. This dispersion was attached to a baffle containing 800 parts by weight of a 0.75% by weight methyl cellulose aqueous solution. 0.05 parts by weight of sodium dodecylbenzenesulfonate was added to the reaction vessel under stirring, and the mixture was stirred at room temperature using a rotor-stator type high-shear stirrer.
Stirred for 10 minutes at 0 rpm. The particle size range of the dispersed particles after stirring was 4-7 microns. Afterwards, the inside of the reaction vessel was degassed and replaced with nitrogen, and the temperature of the system was raised to 70C.
When polymerization was carried out for 6 hours with normal stirring under nitrogen pressure,
A homogeneous polymer slurry was obtained with a conversion rate of 97% to polymer. Thereafter, the remaining seven-layer tube was removed, and after cooling, centrifugal dehydration, washing with water were repeated several times, and the particles were collected by fluidized drying and hot air drying.

The particles thus obtained had an average particle size of 9 microns, and when observed under an electron microscope, it was confirmed that the sphericity was extremely high and magnetite was uniformly encapsulated inside the particles. Furthermore, the degree of agglomeration of the powder was small and the powder fluidity was extremely good. In addition, this product has a high volume resistivity value of 5 x 1010 ohms and good electrical properties.An electrostatic latent image formed on a selenium photoreceptor by ordinary electrophotography is developed using a developing device. When it was transferred to plain paper by corona discharge and fixed, a clear image with no capri or unevenness was obtained.

Example 2 Particles were obtained in the same manner as in Example 1, except that lauroyl chloride was used instead of valmitoyl chloride used in the treatment of Magnetai F in Example 1 ◇The conversion rate to polymer by polymerization was After drying, the particles had an average particle size of 8 microns, were spherical, and had extremely good powder fluidity. The magnetite was completely encapsulated within the particles and was evenly dispersed.

Furthermore, the volume resistivity of the particles was as high as 7×10 10 Ω·1, and when copying was performed in the same manner as in Example 1, fogging occurred.

A clear image without unevenness was obtained.

Example 3 Particles were obtained in the same manner as in Example 1 except that stearoyl chloride was used in place of the balmitoyl chloride used in the treatment of magnetite in Example 1. The conversion rate to polymer by polymerization was 98%, the particles after drying had an average particle size of 10 microns, were spherical, and had extremely good powder fluidity. 9. Magnetite is completely encapsulated within the particles. Moreover, it was in a uniformly dispersed state. In addition, the volume resistivity of the particles is as high as 8 x 10" Ω, and even after continuous copying of 50,000 sheets, there was no clumping in the developing unit, and there was no fog.

A clear image with no unevenness was obtained.

Comparative Example 1 Particles were obtained in the same manner as in Example 1, except that magnetite without surface treatment was used. The conversion rate to polymer by polymerization was 97%, but free magnetite was found in the slurry after polymerization, and after drying, the particles did not contain any magnetite inside, but had magnetite attached only to one surface. It was bad. Further, the volume resistivity value of the particles was as low as 5×10@Ω·1, and the image obtained by the copying machine had low density, unevenness, and many capris, and was not suitable for practical use.

Comparative Example 2 Magnetite 200 whose surface was washed with methanol and thoroughly dried? was placed in a sealed container of No. 21, and the atmosphere was purged with nitrogen. Then, a benzene solution of 5 parts by weight of vinyl-tris(β-methoxyethoxy)silane a was gradually added thereto, and the mixture was stirred at 6°C for 30 minutes to form magnetite. Dispersed in solution. Thereafter, after removing benzene, drying and heat treatment were further performed at 100C for 2 hours to obtain 1 surface-treated magnetite.

Next, particles were prepared in the same manner as in Example 1 except that this surface-treated magnetite was used.

The average particle size of the toner particles after drying was 12 microns. Some of the individual particles contained a small amount of magnetite, but most of the particles only had magnetite attached to their surfaces, and their volume resistivity was as low as 7X10a.
The image obtained by the copying machine was unclear.

Example 4 80 parts by weight of styrene, 20 parts by weight of butyl acrylate, 100 parts by weight of magnetite, 3 parts by weight of stearoyl chloride, 0.5 parts by weight of pyridine, and 5 parts by weight of nib 1 fufu were placed in a reaction vessel from which water had been sufficiently removed. 0.5 at room temperature
After stirring for a period of time, a viscous homogeneous dispersion was obtained. A part of this dispersion was sampled and analyzed by differential spectroscopy in the same manner as in Example 1, and it was found that the carbonyl ester group
i yield was detected.

Next, 2 parts by weight of azobisisovaleronitrile and 2 parts by weight of t-butylmercaptan were dissolved in the dispersion.

After dispersion, 800 parts by weight of a 60% by weight tricalcium phosphate aqueous solution and 0.10 parts by weight of sodium sulfosuccinate were added, followed by ultrasonication for 5 minutes using an ultrasonic disperser at room temperature. Ultrasonic treatment 18- The dispersion state after treatment is good, and the particle size range of the dispersed particles is 6 to 8.
Nine microns. Thereafter, the inside of the reaction vessel was degassed and replaced with nitrogen, and the temperature of the system was raised to 60C while stirring normally. Polymerization was carried out for 7 hours under nitrogen pressure, and the conversion rate to polymer was 96%. Ta. Thereafter, residual monomers were removed, and after cooling, acid was added, washed with water several times, and dried in a spray dryer at an inlet temperature of 150 C, an outlet temperature of 55 C, and an atomizer rotation speed of 5500 rpm, and the particles were recovered. The particles after drying had an average particle size of 8 microns, had an extremely low degree of aggregation, and had good fluidity.

When this particle was observed under an electron microscope, it was confirmed that magnetite was uniformly encapsulated inside each spherical particle. The volume resistivity of this particle is 8X101
I was able to get a clear image with a high resistance of 0 ohms and no unevenness.

Example 5 A uniform dispersion was obtained by stirring 90 parts by weight of styrene, 10 parts by weight of butadiene, 150 parts by weight of magnetite, 3 parts by weight of oleoyl chloride, and parts by weight of Nigrone Sft at room temperature for 0.5 hour.

2 parts by weight of lauryl peroxide and 2 parts by weight of t-dodecyl mercaptan
Added parts by weight. Next, this dispersion was mixed with 800 parts by weight of a 0.75% by weight polyvinyl alcohol aqueous solution and 005% by weight.
After charging into a reaction vessel containing part by weight of sodium sulfosuccinate and adjusting the P'H of the ammonia water system to 8.0,
Closed rotor stator type high shear stirrer #) 30
The mixture was stirred at 00 rpm for 10 minutes. Next, polymerization was carried out at 70C for 6 hours to remove residual monomers, and after cooling, centrifugal dehydration and water washing were repeated several times, and particles were recovered by fluidized drying and hot air drying. The average particle size of the particles after drying was 12 microns.

In addition, this particle is spherical, magnetite is completely and uniformly dispersed inside the particle, and the volume resistivity value is 5X1.
The resistance was as high as 0.010 Ω·1, and even after 50,000 sheets were continuously copied, there was no sagging in the developing unit, and clear images were obtained that did not change over time due to copying.

Example 6 70 parts by weight of acrylonitrile as a monomer component.

An experiment similar to Example 4 was conducted except that 30 parts by weight of methyl acrylate was used, and the conversion rate to polymer after 6 hours was 98%, and the average particle size of the particles after drying was 9 microns. The degree of aggregation was extremely small and the fluidity was good. Furthermore, when we observed these particles using an electron microscope, we found that
It was confirmed that magnetite was evenly encapsulated inside the spherical particles. Further, the volume resistivity of these particles was as high as 7×10 10 Ω, and a clear image with no capri or unevenness was obtained.

Example 7 An experiment similar to Example 4 was conducted except that 10 parts by weight of carbon black was used as a substitute for the magnetite used in Example 4, and the conversion rate to polymer after 7 hours was 96%. , the particles after drying have an average particle size of 12 microns,
The degree of agglomeration was extremely small and the fluidity was good.
The carbon black is uniformly dispersed inside the spherical particles, and the volume resistivity is 5×1011Ω·1. A high-quality, clear image was obtained.

Example Day An experiment similar to Example 1 was conducted, except that the entire amount of balmitoyl chloride-treated magnetite used in Example 1 was added to the polymerization system when the polymerization conversion rate reached 10%. Particles with a particle size of 11 microns were obtained, and when observed with an electron microscope, it was confirmed that magnetite was uniformly encapsulated inside each spherical particle. Furthermore, the degree of agglomeration of the powder was extremely small and the fluidity was good. Moreover, the volume resistivity value of this product was as high as <1×10 10 Ω·min, and clear images without Capri and unevenness were obtained.

From the above examples, it can be seen that the particles obtained by the present invention are extremely useful for electrophotography.

Patent applicant: Zeon Corporation 99-

Claims (1)

[Claims] A method for producing an electrophotographic toner, which comprises aqueous polymerizing a polymerizable monomer in the presence of a pigment treated with an acid halide, and dehydrating and drying the resulting particles.