JP2005092232A - Toner for electrophotography and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for electrophotography which provides an image of high resolution and high sharpness and has stable electrostatic chargeability. <P>SOLUTION: The toner for electrophotography consisting of at least a resin, a coloring agent and a charge control agent is prepared by sticking the charge control agent to the surface in liquid, wherein the absolute value of a saturation electrostatic charge quantity at the time of mixing the toner with a carrier coated with a silicon resin and agitating the mixture is from 10 to 40 μC/g and the degree of carrier contamination is ≤20%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic toner that gives a high-resolution and high-quality image and has stable chargeability, and a method for producing the same.

With the recent digitization of electrophotography, there is a demand for a developer that reproduces a higher quality and higher quality image. In addition, the frequency of outputting presentation materials, digital images created with computers, digital cameras, scanners, etc. is increasing, and the number of full-color copiers and full-color printers for creating hard copies of full-color images continues to increase. Yes. Furthermore, along with the personalization of computers in homes and offices, attempts are being made to reduce the size and cost of these devices, to reduce waste as much as possible, and to increase recyclability. . However, the more functional toner and developer that reproduce high-quality, high-quality images, the more reliable it is, that is, it is difficult to maintain image quality when copying for a long time. It is.

In general, as an electrophotographic toner for forming such an image, a resin lump in which a toner property imparting agent such as a colorant or a charge control agent is dispersed is pulverized in a high-speed air flow to form a fine particle, and then a required particle size is obtained. The manufacturing method which classifies and takes out only the part which has is used. When the resin lump, which is the raw material of the toner, is pulverized inside the pulverizer, the colorant is finely dispersed inside the resin. However, the charge control agent has a larger dispersion diameter than that of the resin, and also has an affinity for the resin. Since it is weak, it tends to be pulverized and separated from the interface between the charge control agent and the resin.

Therefore, contamination and adhesion due to the charge control agent inside the pulverizer may be observed. There is also a problem that such a free charge control agent adheres to the surface of the manufactured toner, and the manufacturability of the toner having a stable charge amount is impaired. The charge control agent on the surface of the toner particles thus pulverized is likely to be detached and peeled off. When a large amount of toner is consumed, contamination by the charge control agent such as the inside of the machine, the developing unit, and the carrier is severe. Image quality deteriorates after long-term running.

Since the toner charging performance is mainly attributed to the vicinity of the surface, the charge control agent inside the kneaded and pulverized toner has little effect on the performance and may be expensive, and should be limited to the surface as much as possible. There are also requests to use it.

As an attempt to improve such a defect, Patent Document 1 (Japanese Patent Laid-Open No. 55-28032) discloses that fine particles of a charge control agent are brought into contact with the surface of a magnetic toner by bringing them into contact with each other at a high temperature in an air stream. There is an attempt. In this case, not only the toners are united and fused by processing at a high temperature, but also the fine particles of the charge control agent do not always cover the toner particle surface evenly. Variation was likely to occur. In addition, the particle size of the charge control agent is smaller than that of the toner particle, but it is not always fixed on the surface, and it may be detached by mechanical external force. Met.

Further, Patent Document 2 (Japanese Patent Laid-Open No. 63-244056) attempted to immobilize the charge controllable particles by passing them through a narrow gap while impacting the surface of the colored particles. However, the dispersion of the coverage ratio among the particles is not controlled at all, and the charge controllable particles immobilized on the surface are caused by mechanical mixing with the carrier particles and friction with the charging blade and the layer thickness regulating blade. It would be detached.

On the other hand, in order to obtain a high-quality, high-quality image, improvements have been made by reducing the particle diameter of the toner or narrowing the particle size distribution. The shape is irregular, and the toner is further pulverized by contact stress with a layer thickness regulating blade or frictional charging blade when used as a one-component developer in the developing unit inside the machine or when it is used as a one-component developer. This causes a phenomenon that the image quality is deteriorated. Further, due to its shape, the fluidity as a powder is poor, a large amount of fluidity-imparting agent is required, and the filling rate into the toner bottle is low, which is an obstacle to downsizing.

Furthermore, in order to create full-color images, the process of transferring images formed from multicolor toners from the photoreceptor to transfer media and paper has become complicated, and poor transferability due to irregular shapes such as pulverized toner. As a result, there are problems such as the transfer of the transferred image and a large amount of toner consumption to compensate for it.

Accordingly, there is a growing demand for further improving transfer efficiency to reduce toner consumption to obtain a high-quality image with no image loss or to reduce running costs.

If the transfer efficiency is very good, there is no need for a cleaning unit for removing untransferred toner from the photoreceptor or transfer medium, which has the advantages of reducing the size and cost of the equipment and eliminating waste toner. Because. Various spherical toner manufacturing methods have been devised to compensate for the disadvantages of such irregular shape effects.

For example, there is an attempt to make a toner by so-called suspension polymerization in which oil droplets composed of a monomer and a toner property imparting agent such as a colorant are formed in water and polymerized into particles. According to this method, since the particles obtained have a true spherical shape, the disadvantage of the shape resulting from the irregular shape of the toner obtained by the above pulverization method can be improved to some extent. However, on the contrary, it is difficult to arbitrarily adjust the shape so that, for example, an intermediate shape between a spherical shape and an indeterminate shape that satisfies both transferability and cleaning property at the same time is difficult.

Furthermore, in the suspension polymerization, it is necessary to increase the conversion rate from the monomer to the polymer up to a high range in the polymerization step, and this requires a long polymerization time. In addition, when the partially moist particles separated from the water are dried, the monomers remaining inside the particles must be removed together with the water. Monomers remaining in the polymer are particularly difficult to remove. This is because, since toner particles usually melt at a temperature of 100 ° C. or lower, the drying temperature is limited. When drying at high temperature and normal pressure is difficult, vacuum drying at low temperature must be carried out, but it still requires long-time treatment. Therefore, the drying cost is also heavy. If the drying is inadequate, toner particles adhere to each other during storage at high temperatures, causing blocking, and even if blocking does not occur, the remaining monomer oozes out to the surface of the particles, resulting in chargeability. Thus, a toner that forms a high-quality image cannot be obtained.

Also, in general, unlike the usual suspension polymerization, when producing toner, the target particle size is very small, so the area of the interface is wide, and a large amount of dispersant (surfactant, inorganic fine particle dispersant, water-soluble Polymer protective colloid). For this reason, the dispersant tends to remain on the particle surface, and since it is the particle surface that dominates the triboelectric chargeability that is most important for the toner, the triboelectric chargeability under high humidity tends to be adversely affected. By washing the particles, we want to eliminate as much as possible the adverse effects of the dispersant, but this requires a large amount of washing water, and the wastewater treatment facility is enlarged, resulting in an increase in cost.

In addition, since suspension polymerization can be regarded as a microscopic bulk polymerization reaction, it is difficult to adjust the molecular weight of the produced polymer to be low or to narrow the molecular weight distribution. This is important when a full color toner is used. The smoothness and transparency of full-color images are important qualities. If the resin used in the toner has a very high molecular weight, the expected image smoothness and transparency can be obtained with the same energy required for fixing as a low molecular weight resin. Absent. Such a low molecular weight polyester having a good fixing property is difficult to be polycondensed in water and cannot be used for producing a suspension polymerization toner.

In addition, a colorant such as a pigment is difficult to finely disperse in a monomer without a dispersant, and if a dispersant is used to obtain good colorability, the chargeability of the manufactured toner has a considerable adverse effect. In addition, if the pigment has a strong hydrophilic property, the pigment moves to the particle interface during the polymerization, dispersibility is impaired, and good color developability and toner characteristics cannot be obtained. Thus, the toner obtained by suspension polymerization obtained in a spherical form also has many problems.

As another method for obtaining a spherical toner, there is a method for producing a spherical toner by forming a droplet of a solution containing the toner in an aqueous medium. In this method, toner property imparting agents such as resins and colorants are dissolved and dispersed in an organic solvent, emulsified to form droplets, and then water and the organic solvent are dried to obtain particles. According to this method, a spherical particle shape can be obtained, but it is difficult to arbitrarily adjust the shape so as to have an arbitrary shape, for example, between a spherical shape and an indefinite shape.

Further, the use of an organic solvent that dissolves in the resin leaves the same problem as the monomer in suspension polymerization. On the contrary, the organic solvent used does not decrease until it is dried and remains as it is, so that it is much more quantitative than removing the monomer. Therefore, the particles in the middle of drying are highly sticky, cause aggregation of the particles, and easily generate coarse particles. Even if a low boiling point solvent is used, a long drying process is required to remove it from the inside of the toner, and if the drying is insufficient, the storage stability and chargeability of the toner are seriously affected. In addition, voids that are traces of evaporation of the solvent are easily generated inside the particles, and the resulting toner is brittle and easily broken. The broken toner in the developing part generates fine particles and a good image cannot be obtained. In addition, since a large amount of solvent is used, it is essential to recover and reuse the solvent, which increases the number of processes and increases costs.

In addition, it is necessary to use a dispersant for stabilizing droplets in water, but this also causes the same problems as suspension polymerization toner, and the influence of the remaining dispersant and a large amount of washing water are required. It is. If a self-emulsifying resin is used as the toner resin, the dispersion stabilizer can be reduced as much as possible, or it can be eliminated in some cases, but the adverse effect on the charging property is manifested by the self-emulsifying resin that tends to be unevenly distributed on the particle surface. To do.

The types of resins that can be used in this method are not as narrow as those of suspension polymerization toners, but are limited to resins that can be dissolved in a water-insoluble organic solvent.

Dispersion of a colorant such as a pigment is often difficult to disperse in a resin solution without a dispersant. If the resin is adsorbed and stabilized by a pigment or the like in the solution, the resin can be dispersed well, but such a guarantee is not necessarily provided. When a dispersant is used, as in the case of the suspension polymerization toner, an adverse effect on the charging property occurs. Further, there is a drawback that only a spherical shape can be selected.

The present inventor disclosed in Japanese Patent Application Laid-Open No. 10-2142838 as an electrophotographic toner having a very small amount of a volatile organic component whose shape is adjusted and containing almost no free fluidizing agent. It has been found that the shape of the particles can be adjusted by heating the primary particles in a liquid that does not dissolve the resin in a very short time. Furthermore, according to this method, it has been proposed that the charge control agent is adhered to the particle surface in order to prevent the charge control agent existing and adhering to the particle surface from detaching and resulting in poor charging characteristics.

The present invention is further developed to prevent the charge control agent from detaching as much as possible and to prevent contamination in the carrier and the developing section.
JP-A-55-28032 Japanese Patent Laid-Open No. 63-244056 JP-A-10-2142838

  A first object of the present invention is to provide an electrophotographic toner having high charging stability over a long period of time.

A second object of the present invention is to provide an electrophotographic toner that does not have image fog or character transfer.

It is another object of the present invention to provide a manufacturing method capable of manufacturing such an electrophotographic toner at a low cost capable of a consistent continuous processing step.

  As a result of intensive studies, the present inventor has found that, when mixed and stirred with a carrier coated with a silicon resin, a) the absolute value of the saturated charge amount is 10 to 40 μC / g, and b) there is a charge control agent in the vicinity of the particle surface. And c) the present inventors have found that the above-mentioned problems can be solved by an electrophotographic toner having a carrier contamination degree of 20% or less, and have reached the present invention.

That is, the present invention is the following (1) and (2).

(1) In an electrophotographic toner comprising at least a resin, a colorant, and a charge control agent, the toner is a toner in which a charge control agent is adhered to the surface in a liquid and mixed and stirred with a carrier coated with a silicon resin. An electrophotographic toner having a saturation charge amount of 10 to 40 μC / g and a carrier contamination degree of 20% or less.

(2) The electrophotographic toner according to claim 1, which does not contain a charge control agent other than near the particle surface.

  That is, according to the present invention, it is possible to obtain a toner with long-term charging stability.

In the present invention, an effect on long-term charge stability, which is the first object of the present invention, is obtained by a toner having a charge control agent in the vicinity of the particle surface and having a low carrier contamination degree.

Specifically, when mixed and stirred with a carrier coated with a silicone resin, a) the absolute value of the saturation charge is 10 to 40 μC / g, b) a charge control agent is present near the particle surface, and c) the carrier. This is achieved with an electrophotographic toner having a contamination degree of 20% or less.

When the absolute value of the saturation charge is lower than 10 μC / g, a low-charge toner remains in the developing portion or a portion other than the latent image on the photosensitive member is developed to obtain a high-quality image corresponding to the latent image. I can't.

On the other hand, if it is larger than 40 μC / g, the amount of toner adhering to the latent image is small and a satisfactory image density cannot be obtained. In addition, the image reproducibility of subtle halftones and highlights is inferior.

Further, since the charge phenomenon occurs on the surface of the toner particle due to the presence of the charge control agent in the vicinity of the particle surface, the function can be sufficiently exerted with a small amount.

Usually, if a charge control agent is present near the toner surface, it tends to be detached, which is undesirable because it contaminates the carrier and the device in the developing unit. It is intended to provide a toner having no toner.

Whether or not the toner is in the vicinity of the toner is determined by using a characteristic element (for example, zinc, fluorine, chromium) of the charge control agent at the apex of one toner particle using micro EPMA (X-ray microanalysis method capable of analyzing a minute portion). Etc.).

When the carrier contamination degree is larger than 20%, the charging ability of the carrier is lowered, and the low-charged toner or the reversely-charged toner is increased.

The carrier contamination degree in the present invention can be measured by the following method.

Mix and stir the toner and carrier at a fixed ratio, periodically sample them, measure the charge amount with a blow-off device, and the time until the charge amount does not change even after mixing and stirring, that is, the time to reach the saturation charge amount Is measured in advance.

Here, “not changed” means that the difference between the previous measurement value and the current measurement value is within 20% of the previous measurement value. The measurement interval is preferably at least 10 minutes.

The blow-off device uses a Q meter and a precision balance to measure the amount of charge Q (coulomb) held by the separated toner and the weight (g) of the toner that has been separated. This is an apparatus for obtaining the charge amount Q / m (charge amount) per unit weight of toner.

Specifically, the same carrier is mixed with a new toner, and the blow-off measurement is repeated, and the difference between the initial charge amount and the charge amount when it is repeated five times is set to the initial charge amount as the carrier contamination degree. evaluate.

That is, the carrier contamination degree (%) representing the change of the charging ability of the carrier when the toner is consumed five times by the toner = 100 × | (Q / m (1) −Q / m (5) | / | Q / m (1) | Here, Q / m (1) represents the initial charge amount, and Q / m (5) represents the charge amount when the toner is consumed five times.

The ratio of the toner and the carrier is determined by the particle size and specific gravity of each toner, and the amount of toner necessary to coat the surface of the carrier is determined. Usually, 1 to 10% of the toner is used with respect to the weight of the carrier. Mixing and stirring are performed by putting each in a stainless steel pot and rotating on a ball mill stand.

The carrier is coated with a silicone resin such as polydimethylsiloxane obtained by crosslinking ferrite or magnetite core material. To optimize the amount of charge, an alkoxysilane monomer having a functional group such as an amino group or a carboxyl group is used. The absolute value of the saturation charge amount may be adjusted to 10 to 40 μC / g by using the modified silicon resin.

The average sphericity was determined by arbitrarily selecting the shape of a large number of toner particles observed with a scanning electron microscope, and using a commercially available image analyzer or flow-type particle image analyzer, for example, trade name: FPIA-1000 manufactured by Sysmex. It can be evaluated by the following formula and is given by

Average sphericity ^{= 100 · Σ (Li 2/} 4 · π · Si)) / N perimeter of a projected image here Li particle, Si is the projected area of the grain N represents the evaluated total particle number.

Specifically, it is evaluated by a flow type particle image analyzer FPIA-1000 manufactured by Sysmex.

This device captures thousands of particles in the liquid and performs image analysis and particle size analysis.

An image having a mean sphericity in the range of 100 to 120 is less susceptible to pulverization inside the developing device, has good fluidity, high transfer efficiency, and gives a high-quality image. It is possible to provide a toner for electrophotography that is free from fog and character transfer.

If the cleaning performance is poor because it is spherical and easy to slip through the blade, the shape may be adjusted to a slightly distorted shape from the true sphere.

When the average sphericity is 120 or less, an external additive is not required, and an effective fluidity can be provided with a very small amount. Furthermore, it is possible to obtain an image that is faithful to a manuscript having no character portion or line portion.

By not containing a charge control agent other than in the vicinity of the particle surface, it is possible to provide a toner for electrophotography that does not have a character portion transfer defect that is a second problem of the present invention. That is, it is possible to eliminate the adverse effect of the non-functional charge control agent, that is, the inhibition of the fixing property and the coloration of the charge control agent itself.

In particular, in the case of a full color toner, a colorless charge control agent must be used to avoid smearing the entire toner with the color of the charge control agent itself, but a small amount of a colored charge control agent with higher performance is placed on the surface. You can also

Further, since the amount of the charge control agent used is greatly reduced, there is an advantage that an inexpensive toner can be obtained.

In particular, a charge control agent (a) that gives an absolute value of the initial charge rate of 10 μC / g · min or more near the particle surface and a charge control agent (b) that has a charge stability coefficient of 50% or less are used. When used in the vicinity, an electrophotographic toner having a long-term stability in charging stability, which is a first problem of the present invention, and a good rise in initial charging can be obtained.

As described above, the charge stability coefficient is obtained by obtaining the charge amount after stirring for 3 hours and comparing the absolute value of the charge amount difference with the saturated charge amount with the saturated charge amount by the following equation.

Charging stability coefficient = 100 × (| saturated charge amount−after stirring for 3 hours |) / | saturated charge amount | This value is less than 50%. Toner is selected as the charge control agent used in the present invention. Of course, those that do not reach the saturation charge amount within 3 hours are excluded.

The charge control agent that gives an absolute value of the initial charging rate of 10 μC / g · min or more is preferably an aromatic organic acid metal salt or complex, such as an alkyl group such as a benzoic acid derivative or an aromatic dicarboxylic acid, or a hydroxy group. Metals such as Na, Mg, Al, K, Ca, Cr, Fe, Co, Ni, Cu, Zn, such as salicylic acid, isophthalic acid derivatives, terephthalic acid derivatives, phthalic acid derivatives, naphthoic acid derivatives, etc., into which functional groups have been introduced A salt or a complex is mentioned.

The charge control agent having a charge stability coefficient of 50% or less is preferably a quaternary ammonium salt having a perfluoroalkyl group, and specific examples thereof include the following.

In the above general formula, X ⁻ representing an organic or inorganic anion is, for example, Cl ⁻ , Br ⁻ , or I ⁻ and / or PF ₅ ⁻ , sulfate, phosphate, cyanate, thiocyanate, BF ₄ ⁻ , B (aryl) _4. ^- , For example, tetraphenylborate, p-chlorotetraphenylborate, p-methyltetraphenylborate, tetranaphthylborate and / or phenolate, nitrophenolate, zinc tetracyanate, zinc tetrathiocyanate, CH ₃ OSO ₃ ⁻ , saturated or unsaturated aliphatic, or aromatic carboxylate, or sulfonate, such as acetate, lactate, benzoate, salicylate, 2-hydroxy-3-naphthoate, 2-hydroxy-6-naphthoate, ethyl sulfonate, Feni A sulfosulfonate and / or a perfluorinated saturated or unsaturated aliphatic or aromatic carboxylate, or a sulfonate such as perfluoroacetate, perfluoroalkyl benzoate, perfluoroethyl sulfonate, or perfluoroalkyl benzoate can be selected.

Further, when the charge control agent (a) and the charge control agent (b) are each used in an amount of 1% by weight or less based on the total amount of toner for electrophotography, combined with the shape where any outermost surface of the toner can come into contact with the carrier, The probability of contact with the carrier is increased, and a long-term stable toner with stable charging, which is the first problem of the present invention, can be obtained.

Furthermore, when it exists in the particle surface vicinity, the usage-amount of the charge control agent (b) which has a particularly expensive perfluoro group can be reduced. In addition, if it is 1% by weight or less, it is effective for the image fogging and character portion transfer, which is the second problem of the present invention, and further, it is possible to improve the fixing property and to reduce the inhibition of the coloring property in the color toner as much as possible. It is in.

In the case of an ordinary kneading and pulverizing toner, these charge control agents are usually used in an amount of several weight% of the total toner, but in the present invention, an amount of 1 weight% or less is sufficient. More preferably, it is sufficient to use 0.5% by weight or less. If it is used in a large amount, the result is that the charge control agent is contaminated on the member in contact with the toner.

Hereinafter, materials constituting the toner according to the present invention will be described.

Examples of the colorant used in the toner of the present invention include carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, Examples thereof include lamp black, rose bengal, xanthene pigment, benzidine yellow organic pigment, quinacridone organic pigment, methine organic pigment, thioindigo organic pigment, azo lake organic pigment, a mixture thereof, and the like.

Other charge control agents used in the present invention include Nigrosine dye Bontron 03, quaternary ammonium salt Bontron P-51, metal-containing azo dye Bontron S-34, and oxynaphthoic acid metal complex E-82. , Salicylic acid metal complex E-84, phenol condensate E-89 (above, manufactured by Orient Chemical Industries), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.) Co., Ltd.), quaternary ammonium salt copy charge PSYVP2038, triphenylmethane derivative copy blue PR, quaternary ammonium salt copy charge NEG VP2036, copy charge NX VP434 (above, Hoechst), LRA-901 LR-147 (Nippon Carlit Co., Ltd.), a copper complex, which is a boron complex Examples include talocyanine, perylene, quinacridone, azo pigments, and other high molecular compounds having a functional group such as a sulfonic acid group, a carboxyl group, and a quaternary ammonium salt.

In order to impart releasability to the manufactured toner, it is preferable to include a wax in the manufactured toner. The wax has a melting point of 40 to 120 ° C., and preferably 50 to 110 ° C. When the melting point of the wax is excessive, the fixing property at a low temperature may be insufficient. On the other hand, when the melting point is excessively low, the offset resistance and durability may be decreased. The melting point of the wax can be obtained by differential scanning calorimetry (DSC). That is, the melting peak value when a sample of several mg is heated at a constant temperature increase rate, for example, (10 ° C./min) is defined as the melting point.

Examples of the wax that can be used in the present invention include solid paraffin wax, micro wax, rice wax, fatty acid amide wax, fatty acid wax, aliphatic monoketone, fatty acid metal salt wax, fatty acid ester wax, and partial kenne. And fatty acid ester wax, silicone varnish, higher alcohol, carnauba wax and the like. Also, polyolefins such as low molecular weight polyethylene and polypropylene can be used. Particularly, a polyolefin having a softening point of 70 to 150 ° C. by the ring and ball method is preferable, and a polyolefin having a softening point of 120 to 150 ° C. is more preferable.

As the fluidizing agent, inorganic fine particles can be preferably used. The primary particle diameter of the inorganic fine particles is preferably 5 mμ to 2 μm, particularly preferably 5 mμ to 500 mμ, and the specific surface area by the BET method is preferably 20 to 500 m ² / g. The proportion of the inorganic fine particles used is preferably 0.01 to 5% by weight of the toner, and particularly preferably 0.01 to 2.0% by weight. Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, oxidation Examples thereof include chromium, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

Such a fluidizing agent can be surface-treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. For example, a silane coupling agent, a silane coupling agent having a fluorinated alkyl group, an organic titanate coupling agent, an aluminum coupling agent and the like are preferable surface treatment agents.

Examples of the cleaning improver include fatty acid metal salts such as zinc stearate, calcium stearate and stearic acid, polymer fine particles produced by soap-free emulsion polymerization such as polymethyl methacrylate fine particles and polystyrene fine particles.

When the magnetic toner is used, the toner particles may contain magnetic fine particles. Such magnetic materials include ferrite, magnetite and other iron, nickel, cobalt and other metals or alloys exhibiting ferromagnetism, compounds containing these elements, and ferromagnetic elements that do not contain ferromagnetic elements but are subjected to appropriate heat treatment. Examples include alloys that exhibit magnetism, for example, a kind of alloy called Heusler alloy containing manganese and copper, such as manganese copper aluminum and manganese copper-tin, chromium dioxide, and the like. It is preferable that the magnetic material is contained in a uniformly dispersed form in the form of fine powder having an average particle size of 0.1 to 1 μm. The content of the magnetic material is preferably 10 to 70 parts by weight, particularly 20 to 50 parts by weight, based on 100 parts by weight of the obtained toner.

Anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, as dispersing agents for wetting and dispersing the primary particles in a liquid containing water, Cation of amine salt type such as polyamine fatty acid derivative, imidazoline, and quaternary ammonium salt type such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride Nonionic surfactants such as surfactants, fatty acid amide derivatives, polyhydric alcohol derivatives such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethyl Amphoteric surfactants such as Nmo betaine and the like.

Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [omega-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [omega-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkylcarboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-hydroxyethyl) -Fluorooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Is mentioned.

Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F-150 (manufactured by Neos).

Cationic surfactants include aliphatic primary, secondary or secondary amine acids having a fluoroalkyl group, aliphatic quaternary ammonium salts such as perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salts, benza Luconium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (Asahi Glass), Florard FC-135 (Sumitomo 3M), Unidyne DS-202 (Daikin Industries) Megafac F-150, F-824 (manufactured by Dainippon Ink, Inc.), Xtop EF-132 (manufactured by Tochem Products), and Footgent F-300 (manufactured by Neos).

Further, tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, hydroxyapatite and the like can be used as an inorganic compound dispersant which is hardly soluble in water.

Further, the primary particles may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride, or other (meth) acrylic simple substances containing hydroxyl groups Such as β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-acrylate Chloro-2-hydroxypropyl, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or esters of compounds containing vinyl alcohol and carboxyl groups Such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl imidazole, Homopolymers or copolymers such as those having a nitrogen atom such as ethyleneimine or its heterocyclic ring, polyoxyethylene, polyoxypropylene , Polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonyl Polyoxyethylenes such as phenyl esters, celluloses such as methyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose can be used.

The resin constituting the toner in the present invention is, for example, a heavy polymer that contains at least one selected from a styrene monomer, a (meth) acrylic monomer, and a (meth) acrylic acid ester monomer as an essential component. It is preferable that it is composed of coalescence. Examples of the styrene monomer that can be used include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,3-dimethylstyrene, 2, 4-dimethylstyrene, pn-butylstyrene, pt-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn -Dodecyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,4-dichloro styrene, etc. can be mentioned. These monomers may be used alone or in combination of two or more.

Examples of the acrylic ester or methacrylic ester that can be used include methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, propyl acrylate, octyl acrylate, dodecyl acrylate, lauryl acrylate, and acrylic acid. Acrylate esters such as 2-ethylhexyl, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate; for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate , Isobutyl methacrylate, octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, methacryl Dimethylaminoethyl methacrylate esters such as diethylaminoethyl methacrylate; and the like.

Further, a polyester resin, an epoxy resin, or a polyol resin may be used as a resin constituting the toner. The polyhydric alcohol constituting the polyester resin includes an ethylene oxide adduct of bisphenol A, a propylene oxide adduct of bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, Examples of 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol and trifunctional or higher alcohols include trimethylolpropane and pentaerythritol. Polyester acids constituting the polyester resin include terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylene dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, and suberin. Examples of the acid, azelaic acid, sebacic acid, dodecanedioic acid, and trifunctional or higher acid components include trimellitic acid and pyromellitic acid. If a trihydric or higher polyhydric alcohol or polyvalent carboxylic acid is used, the resin may be cross-linked, which may be advantageous for offset resistance.

Examples of the epoxy resin and polyol resin include resins made from bisphenol A and epichlorohydrin, polyol glycidyl ester type, and polyacid glycidyl ester type.

The toner of the present invention can be manufactured by any method, but can be manufactured at a low cost that enables a consistent continuous processing step, particularly by the following manufacturing method.

When the primary particles of the present invention are pulverized and manufactured without using a charge control agent, it is very advantageous as a raw material cost. In particular, the pulverization is performed when the charge control agent is an interface for particle division. It may become difficult and may require a long manufacturing time or large equipment.

In that case, the disadvantages can be avoided by dispersing the above-mentioned fluidizing agents, organic, inorganic pigments, and magnetic materials that do not affect the toner characteristics into primary particles as grinding aids in advance.

As another method, a composition containing a charge control agent is added, and the composition containing the charge control agent is fixed to the surface of the primary particles, so that the surface of the primary particles has a low physical strength due to mechanical agitation. The removed toner having an appropriate charging ability as an electrophotographic toner can be produced.

In the present invention, a conventionally known method, that is, preparing primary particles composed of at least a resin and a colorant, dispersed in a liquid that does not dissolve the resin, including a dispersant, and then heated and cooled, In a method for producing an electrophotographic toner by a washing step and a drying step as necessary, a composition containing a charge control agent is added before heating, during heating, after cooling, or after washing, and a composition containing the charge control agent is added. By adhering to the surface of the primary particles, it is possible to produce a toner having an appropriate charging ability as an electrophotographic toner having a low physical strength by mechanical stirring on the surface of the primary particles and from which protrusions are removed.

In this method, the transfer property is further improved by processing the toner by adjusting the shape by performing heating for 30 minutes or less at a softening point of the resin + 30 ° C. or less, and selecting the heating temperature and the heating time. An excellent image reproducible toner satisfying the cleaning property can be produced.

Furthermore, by adding an organic solvent that dissolves or swells the resin in a liquid that does not dissolve the resin, which contains a dispersant, the heat treatment temperature is lowered, and aggregation and adhesion between primary particles are suppressed, and a toner is obtained with high yield. be able to.

In particular, this is a very effective means for processing primary particles having a high melt viscosity in order to widen the fixing range, such as a monochrome toner.

By using a pulverized product in which at least a resin, a colorant, and a pulverization aid are kneaded and used as primary particles, the pulverizability is improved and a toner can be produced at low cost.

Usually, when pulverization is performed by adding a pulverization aid or the like, it becomes easy to break, but there is a disadvantage that it becomes brittle, but by performing the treatment according to the present invention, the adhesion between the resin and the pulverization aid is increased in the primary particles. It can be hard and mechanically strong.

Alternatively, by using primary particles to which a fluidizing agent having the same polarity as that of the base and the frictional charging property is attached, not only the fluidity of the obtained toner but also the one having excellent charging property can be obtained.

The reason for this is generally considered that the base and the oppositely charged fluidizing agent adhere more firmly to the base particles and favor the subsequent processing step. Even when the fluidizing agent is dispersed in the treatment medium, the primary particles are prevented from adhering or agglomerating without separating from the surface of the base particles, and the resulting toner is fixed on the surface of the base material. It has been found that it is possible to obtain an extremely excellent toner that has excellent fluidity, little reverse charge, no scattering, and little soiling.

That is, it is considered that the interaction between the fluidizing agent and the matrix is dominated by the van der Waals force regardless of the charge between the particles.

Or a) a zone in which primary particles comprising at least a resin and a colorant are dispersed in a liquid containing water; b) a zone in which the dispersion is heated while flowing; c) a charge control agent composition or a release agent composition. A zone for fixing an object to the particle surface, d) extremely efficient (by a low energy, compact manufacturing device) by making it a continuous process step with a zone for washing and drying the resulting particle dispersion. A low-cost toner can be manufactured.

According to the present invention, the shape in which the charge control agent is present in the vicinity of the surface where the excellent image quality is maintained for a long time and the charge control agent is prevented from being contaminated with little desorption is prevented. An electrophotographic toner can be obtained by an industrially feasible process.

Specifically, the toner is manufactured by the following procedure described in the continuous flow process of FIG.

1. Preparation of primary particles Although it is desirable that the primary particles are close to the average particle size and particle size distribution of the toner as the final product, the range is not particularly considered if the production method of the present invention is used. Absent.

The production method is not limited as long as a toner property imparting agent such as a colorant, a magnetic material, a charge control agent, and a release agent is dispersed in the resin.

When primary particles are produced by a pulverization method, the charge control agent is buried or detached from the particle surface in the subsequent process, and therefore it is preferable to produce primary particles without using a charge control agent.

In addition, the shape is preferably indefinite for adjusting the shape later, but may be spherical. Although the volatile organic component contained in the primary particles can be removed in a subsequent shape adjustment step, it is desirable to reduce the amount of the volatile organic component from the beginning if possible in consideration of the removal effort.

2. Mixing with a fluidizing agent Normally, after the form of toner particles is obtained, a fluidizing agent is obtained by mixing, for example, a powder obtained after kneading, pulverizing, and classifying a resin and a colorant, and a powder of the fluidizing agent. The fluidizing agent is adhered to the toner surface. In the present invention, it is preferable to prepare a material in which the fluidizing agent is adhered to the primary particles and perform the shape adjusting step.

By mixing with a fluidizing agent before the shape adjustment step, the fluidizing agent adhering to the primary particle surface during the shape adjustment step can be fixed, and the floating fluidizing agent detached from the primary particles can also be fixed. it can.

The fluidizing agent also plays an important role in preventing aggregation of primary particles during shape adjustment. The fluidizing agent exhibits its effect sufficiently at 2% by weight or less with respect to the primary particles.

The use of a large amount of fluidizing agent should be avoided because it is preferable to eliminate fluidizing agents other than those present on the toner surface. The charging polarity of the fluidizing agent is preferably the same as that of the base before mixing, and the charging characteristics of the toner that can be reversely charged become unstable, so that a high-quality image cannot be obtained.

3. Mixing with shape control medium (in the presence of dispersant)
If necessary, primary particles mixed with a fluidizing agent are mixed with a shape-controlling medium and dispersed. Here, the shape adjusting medium refers to a liquid that does not dissolve the resin that constitutes the primary particles, but may be a mixed liquid or emulsion with an organic solvent that swells or dissolves the resin that constitutes the primary particles.

Shape control media include water, alcohols such as methanol and ethanol that can be diluted infinitely with water, ketones such as acetone, aromatics such as benzene and toluene, paraffinic hydrocarbons such as n-hexane, and other halogens. Series hydrocarbons can also be used.

The shape of a toner that uses a resin with a high molecular weight with a cross-linking component or a weight average molecular weight of several hundred thousand or more when used as a mixed liquid or emulsion that swells or dissolves the resin constituting the primary particles. Adjustments can be made.

Using mixed liquids and emulsions with organic solvents that swell or dissolve the resin that constitutes the primary particles can make the primary particles easier to disperse and lower the heating temperature. Time and energy are required, resulting in high production costs.

In the shape adjusting medium, it is necessary for the primary particles to be wetted with the liquid, and for the primary particles to be present separately in the liquid, the dispersant should be present together. It is desirable that the dispersant is dissolved and dispersed in the shape adjusting medium in advance.

4). Shape adjustment (including aggregation)
The primary particles are added to the liquid containing the dispersant, and a mixing operation such as stirring is performed until the particles are completely wetted and dispersed.

Thereafter, the shape is adjusted by heating at a temperature near the softening point of the resin, preferably with gentle stirring so that the primary particles do not settle and float.

Heating is preferably performed for 5 minutes or more after reaching the target temperature.

The shape is determined by the heating time and the heating time, but even if the heating time is lengthened, the desired shape cannot be obtained if the set temperature is low.

If the primary particles contain a large amount of fine particles and are different from the desired particle size distribution, the fine particle components can be selected, destabilized and aggregated in the liquid, and then fused to adjust the particle size distribution.

For example, an appropriate temperature necessary for aggregation, mechanical energy, ionic force, swelling by a solvent, and the like can be used. According to such means, primary particles that do not require classification are used, which is advantageous for cost and process simplification.

5). Addition of charge control agent When the charge control agent is uniformly dispersed or adhered to the surface of the primary particles, the charge control agent moves to the inside of the toner particles by the particle shape adjustment treatment such as heating, Since the triboelectric chargeability is insufficient, the characteristics are exhibited by attaching and fixing a charge control agent to the toner surface.

For example, the following method can be used to adhere and fix the charge control agent on the toner surface.

(1) A method in which primary particles and a charge control agent are mixed in a dry manner to cause the charge control agent to adhere to the surface, and thereafter, a particle shape adjustment treatment is performed in the liquid to immobilize on the particle surface.

(2) A method in which primary particles are dispersed in a liquid containing water, or after heat treatment and mixed with a composition containing a charge control agent, and then fixed on the particle surface by performing subsequent steps.

In that case, the liquid which melt | dissolves or swells the resin which comprises a primary particle can exist, and also fixation can be advanced. The composition containing the charge control agent contains a liquid that dissolves the charge control agent that can be diluted by the shape adjusting medium, and precipitates when mixed with the primary particle dispersion, and is 1 micron or less, preferably 0.1. It is important to aim to reduce the particle size to less than a micron. Such a fine charge control agent adheres firmly to the vicinity of the particle surface by van der Waals force or electrostatic force, and can prevent contamination of carrier particles and the developing part when used as a toner.

Further, if the charge control agent is present at the time of adjusting the shape of the primary particles as described above, the surface resin is fused and fixed, and the effect can be further exhibited. In order to allow the finely charged charge control agent to stably exist in the liquid without aggregation, stabilizers, resins, inorganic, organic fine particles, and the like can be used at the same time.

6). Cooling (cooling below the softening point of the resin, preferably to room temperature)
By controlling the crystallization of the resin or wax according to the cooling rate, the fixability and storage stability can be adjusted.

7). Classification (Recycling of fine particles, re-kneading, aggregation toner)
When the particle size distribution of the primary particles is wide and the shape adjustment process is performed while maintaining the particle size distribution, the particle size distribution can be adjusted by classification into a desired particle size distribution.

In the classification operation, the fine particle portion can be removed in the liquid by a cyclone, a decanter, centrifugation, or the like. Of course, the classification operation may be performed after obtaining the powder after drying, but it is preferably performed in a liquid in terms of efficiency. The obtained unnecessary fine particles or coarse particles can be used again to form primary particles.

Further, when the primary particles are produced by kneading a resin and a pigment, fine particles or coarse particles can be kneaded at the same time. At that time, fine particles or coarse particles may be wet.

Then, the yield can be increased by changing the product particle size by a method in which only the separated fine particles are aggregated during shape adjustment.

8). The dispersant used for washing is preferably removed from the obtained dispersion as much as possible, but is preferably performed simultaneously with the classification operation described above.

In addition, the dispersant adhering to the obtained particles can be removed by an operation such as acid-alkali treatment or enzymatic decomposition.

9. Drying The toner according to the present invention can be processed by a normal drying apparatus in the form of a dispersion or in the form of a cake containing moisture.

Sufficient quality can be obtained with a short treatment such as spray dryer, belt dryer or rotary kiln.

10. The surface-treated dry toner powder is mixed with different kinds of particles such as release agent fine particles, charge control fine particles, fluidizing agent fine particles, and colorant fine particles, and mechanical impact force is applied to the mixed powder. As a result, it is possible to prevent the dissociation of the foreign particles from the surface of the composite particle obtained by immobilizing and fusing on the surface.

Specific means include a method of applying an impact force to the mixture by blades rotating at high speed, a method of injecting and accelerating the mixture in a high-speed air stream, and causing particles or composite particles to collide with an appropriate collision plate, etc. is there. As equipment, Ong mill (manufactured by Hosokawa Micron Co., Ltd.), I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) was modified to reduce the pulverization air pressure, hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron system (Made by Kawasaki Heavy Industries, Ltd.), automatic mortar and the like.

The process of the present invention is suitable for a continuous production process because each process is performed in a short time.

The prepared primary particles and the shape adjusting medium containing the dispersant are simultaneously supplied to the mixer and mixed and dispersed. The obtained dispersion is processed by passing through the shape adjustment zone by heating for a short time with a residence time of the order of minutes while flowing.

If the treatment is performed by adding the atomized charge control agent composition, the charge control agent can be firmly attached and fixed in the vicinity of the particle surface. Next, if necessary, classification treatment and washing treatment are performed at the same time, and a product is obtained through a drying treatment zone.

The charge control agent composition can be added immediately before the drying process after the cleaning process is completed. Fine particles and coarse particles removed by classification can be recycled to primary particles or commercialized through agglomeration treatment, pulverization treatment, and the like. Further, the shape adjusting medium after processing can be recycled.

In the toner of the present invention, the fluidizing agent or charge control agent adhering to the primary particles can be fixed to the toner particle surface so as not to be detached.

Floating fluidizers and charge control agents that are usually detached from the toner or not attached to the toner contaminate the photoconductor and carrier, damage the photoconductor, wear the cleaning blade, etc. Often.

Such a charge control agent or fluidizing agent that has been detached or floated can be easily confirmed by observation with a scanning electron microscope, but more accurately, the toner is dispersed in a liquid that does not dissolve the toner. Then, the toner and the liquid are separated, and the desorbed charge control agent and fluidizing agent contained in the liquid may be quantified.

The quantification includes a method of measuring the turbidity of the liquid, a method of detecting solid inorganic elements and organic elements contained in the liquid, and the like.

For example, when the toner is kneaded and then pulverized for production, a colorant, a magnetic material, a charge control agent, a release agent and the like are exposed on the pulverized particle surface. These toner constituent components may be detached from the particles and dropped by stirring inside the developing unit to contaminate the apparatus, the photoreceptor, the carrier, and the like. Further, according to the suspension polymerization or solution emulsification dispersion method in which particles are produced in water, the hydrophilic component moves to the water / particle interface and deteriorates the toner characteristics as described above. In the toner of the present invention, constituent components other than the resin existing on the outer surface of the primary particles are subjected to heat treatment under specific conditions to move from the outermost surface of the particles to the inside. It is intended to eliminate the adverse effects of desorption.

The internal state of the toner can be determined by embedding the toner in a resin, cutting out an ultrathin section, and observing with a transmission electron microscope, if necessary, by staining with osmium or ruthenium. Of course, if there is a void (cavity) inside the toner, its presence can be immediately known from the contrast difference.

Examples Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. Needless to say, this embodiment is only a part of the present invention, and is not limited to this embodiment.

Example 1
A polycondensation polyester resin (softening point: 70 ° C) of terephthalic acid and bisphenol A polyoxyethylene adduct is mixed with a powder consisting of 3 parts by weight of a copper phthalocyanine pigment, and heated and kneaded and dispersed by a three-roll kneader. After cooling, the kneaded product was coarsely pulverized. The obtained coarsely pulverized product was pulverized by a jet mill, fine particles were removed by an air classifier, and 100 parts by weight of the obtained powder and 0.8 parts by weight of hydrophobic silica R972 (manufactured by Nippon Aerosil Co., Ltd.). Were mixed with a mixer to obtain primary particles.

40 parts by weight of primary particles were added to 100 parts by weight of ion-exchanged water having a concentration of 0.1% by weight of sodium lauryl sulfate while stirring, and stirring was continued for 10 minutes.

After 10 minutes, it was visually confirmed that there was no powder floating and the primary particles were completely wetted with the aqueous solution, and it was also confirmed by an optical microscope that the primary particles were separated and dispersed.

The obtained dispersion was subjected to centrifugal sedimentation, supernatant removal, and redispersion with the same amount of ion-exchanged water as the removed supernatant. By repeating this operation three times, a purified dispersion of primary particles was obtained.

Separately, 0.3 parts by weight of zinc di-t-butylsalicylate was added to 20 parts by weight of methanol and dissolved. 20 parts by weight of ion exchange water was gradually added dropwise to this solution to prepare a finely dispersed dispersion of zinc di-t-butylsalicylate.

The obtained dispersion of zinc di-t-butylsalicylate was added to the previously obtained primary particle dispersion while stirring, further immersed in an ultrasonic probe, and dispersion was advanced by ultrasonic waves. Then, while stirring, the internal temperature was raised to 50 ° C. by heating with warm water from the outside of the container, maintained for 10 minutes as it was, and then cooled to 20 ° C. This was dried by a spray dryer GS31 (manufactured by Yamato Kagaku) to a hot air temperature of 80 ° C. and an outlet temperature of 50 ° C. to obtain a toner.

A developer is prepared by mixing 5 parts by weight of the toner with 100 parts by weight of a ferrite carrier having an average particle diameter of 50 μm coated with a silicon resin with an average thickness of 0.3 μm, and evaluating the chargeability and image. The results are summarized in a table.

In addition, the saturation charge amount of the base particles before mixing when making primary particles with this carrier is −8 μC / g, and the chargeability with the hydrophobic silica R972 alone is measured to be −125 μC / g and the same polarity as the base particles. Amount indicated.

In addition, the image evaluation and the running test of 10,000 sheets are Examples 1, 2-1, 2-2, 3-1, 3-2, 4-1, 4-2, and Comparative Examples 1, 2, and 3 are respectively Ricoh. Examples 6 and 7 and Comparative Examples 4 and 5 were evaluated by Ricoh's digital copier Imagio DA-250, using a full color copier pre-tail 550.

Among the following evaluation items, (1) saturation charge amount, (2) confirmation of the presence of the charge control agent near the particle surface, (3) carrier contamination degree, and (4) average sphericity have already been described. Therefore, the details are omitted.

(1) Saturation charge amount (2) Confirmation of presence of charge control agent near particle surface (3) Carrier contamination degree (4) Average sphericity (5) Long-term charge stability Charge amount at the initial stage of printing and 10,000 sheets If the absolute value of the difference from the charge amount after the running test is within 5 μC / g, it can be said that the charging stability is high.

(6) Image fogging (7) Any missing part of the character part image was visually determined using a magnifying glass.

Comparative Example 1
Powder comprising 100 parts by weight of the polyester resin used in Example 1, 3 parts by weight of copper phthalocyanine pigment, and 3 parts by weight of zinc di-t-butylsalicylate was mixed, heated and kneaded and dispersed by a three-roll kneader and cooled. Thereafter, the kneaded product was coarsely pulverized. The obtained coarsely pulverized product was pulverized by a jet mill.

The powder adhering to the inside of the pulverizer was sampled, and the zinc content was quantified by elemental analysis. As a result, the amount of zinc contained was about 50 times that of the powder obtained by pulverization.

That is, it was found that the ratio of the charge control agent present on the pulverized particle surface was high because the powder was preferentially pulverized from the interface where the charge control agent zinc di-t-butylsalicylate was present.

Thereafter, the fine particle portion was removed with an air classifier, and 100 parts by weight of the obtained powder and 0.8 part by weight of hydrophobic silica were mixed with a mixer to obtain a toner.

The developer was prepared in the same manner as in Example 1, and chargeability evaluation and image evaluation were performed and the results are summarized in a table.

In this toner, a charge control agent 10 times as much as the toner of Example 1 is used. This is because satisfactory charge characteristics cannot be obtained unless a charge control agent is used in such a large amount.

Example 2-1
The primary particles were obtained by kneading, pulverizing, and classifying with the same materials as in Example 1.

40 parts by weight of primary particles were added to 100 parts by weight of ion-exchanged water having a concentration of 0.1% by weight of sodium lauryl sulfate while stirring, and stirring was continued for 10 minutes. After 10 minutes, it was visually confirmed that there was no powder floating and the primary particles were completely wetted with the aqueous solution, and it was also confirmed by an optical microscope that the primary particles were separated and dispersed.

While stirring, the internal temperature was raised to 60 ° C. (this temperature is referred to as “treatment temperature”) by heating with warm water from the outside of the container, maintained for 10 minutes as it was, and then cooled to 20 ° C. The obtained dispersion was subjected to centrifugal sedimentation, supernatant removal, and redispersion with the same amount of ion-exchanged water as the removed supernatant.

By repeating this operation three times, a purified dispersion of primary particles was obtained.

Subsequent operations were performed in exactly the same manner as in Example 1, toner and developer were obtained, chargeability evaluation and image evaluation were performed, and the results are summarized in a table.

Example 2-2
A toner was obtained in the same manner as in Example 2-1, except that the treatment temperature was changed to 70 ° C. The developer was prepared in the same manner as in Example 1, and chargeability evaluation and image evaluation were performed and the results are summarized in a table.

Example 3-1.
The primary particles were obtained by kneading, pulverizing, and classifying with the same materials as in Example 1.

40 parts by weight of primary particles obtained were added to 100 parts by weight of ion-exchanged water having a concentration of 0.15% by weight of polyoxyethylene sorbitan monooleate (Tween 80), and stirring was continued for 10 minutes. After 10 minutes, it was visually confirmed that there was no powder floating and the primary particles were completely wetted with the aqueous solution, and it was also confirmed by an optical microscope that the primary particles were separated and dispersed.

While stirring, the treatment temperature was raised to 60 ° C. by heating with warm water from the outside of the container, and maintained for 10 minutes as it was, and then cooled to 20 ° C. The obtained dispersion was subjected to centrifugal sedimentation, supernatant removal, and redispersion with the same amount of ion-exchanged water as the removed supernatant. By repeating this operation three times, a purified dispersion of primary particles was obtained.

Separately, 0.2 part by weight of NX-VP434 (Hoechst), which is a quaternary ammonium salt having a perfluoro group, was added to 20 parts by weight of ethanol and dissolved. 20 parts by weight of ion exchange water was gradually added dropwise to this solution to prepare a finely dispersed dispersion.

The obtained dispersion of NX-VP434 was added to the previously obtained primary particle dispersion while stirring, and the ultrasonic probe was further immersed therein, followed by ultrasonic irradiation for 5 minutes to promote dispersion. Then, while stirring, the internal temperature was raised to 50 ° C. by heating with warm water from the outside of the container, maintained for 10 minutes as it was, and then cooled to 20 ° C. This was dried by a spray dryer GS31 (manufactured by Yamato Kagaku) at a hot air temperature of 80 ° C. and an outlet temperature of 50 ° C. to obtain a toner.

Similarly to Example 1, this toner was also mixed with 5 parts by weight of toner and 100 parts by weight of a ferrite carrier having an average particle diameter of 50 μm coated with silicon resin at an average thickness of 0.3 μm, and charged with toner. Sexuality evaluation and image evaluation were performed and the results were summarized in a table.

Example 3-2
A toner was obtained exactly as in Example 3-1, except that the treatment temperature was changed to 70 ° C. The developer was prepared in the same manner as in Example 1, and chargeability evaluation and image evaluation were performed and the results are summarized in a table.

Comparative Example 2
After mixing 100 parts by weight of the polyester resin used in Example 1, 3 parts by weight of a copper phthalocyanine pigment, and 2 parts by weight of NX-VP434, the mixture was heated and kneaded and dispersed by a three-roll kneader, and cooled. The kneaded product was coarsely pulverized. The obtained coarsely pulverized product was pulverized by a jet mill.

The powder adhering to the inside of the pulverizer was sampled, and the fluorine content was quantified by elemental analysis. As a result, the amount of fluorine contained was about 35 times that of the powder obtained by pulverization.

That is, since the particles are preferentially pulverized from the interface where the charge control agent NX-VP434 is present, the ratio of the charge control agent existing on the pulverized particle surface is high.

Thereafter, the fine particle portion was removed with an air classifier, and 100 parts by weight of the obtained powder and 0.8 part by weight of hydrophobic silica were mixed with a mixer to obtain a toner.

The developer was prepared in the same manner as in Example 1, and chargeability evaluation and image evaluation were performed and the results are summarized in a table.

In this toner, a charge control agent 10 times as much as the toner of Example 3 is used.

Example 4-1
The primary particles were obtained by kneading, pulverizing, and classifying with the same materials as in Example 1. 40 parts by weight of primary particles were added to 100 parts by weight of ion-exchanged water having a concentration of 0.1% by weight of sodium lauryl sulfate while stirring, and stirring was continued for 10 minutes.

After 10 minutes, it was visually confirmed that there was no powder floating and the primary particles were completely wetted with the aqueous solution, and it was also confirmed by an optical microscope that the primary particles were separated and dispersed.

While stirring, the internal temperature was raised to 60 ° C. by heating with warm water from the outside of the container, maintained for 10 minutes as it was, and then cooled to 20 ° C. The obtained dispersion was subjected to centrifugal sedimentation, supernatant removal, and redispersion with the same amount of ion-exchanged water as the removed supernatant. By repeating this operation three times, a purified primary particle dispersion was obtained.

Separately, 0.3 parts by weight of zinc di-t-butylsalicylate and 0.2 parts by weight of NX-VP434 were added to 20 parts by weight of methanol and dissolved. When 20 parts by weight of ion-exchanged water was gradually added dropwise to this solution, it became slightly cloudy, but particles could not be confirmed with an optical microscope. Therefore, it is thought that it is a submicron dispersion.

The obtained dispersion of zinc di-t-butylsalicylate and NX-VP434 was added to the previously obtained primary particle dispersion with stirring, and an ultrasonic probe was further immersed to disperse by ultrasonic waves. Then, while stirring, the internal temperature was raised to 50 ° C. by heating with warm water from the outside of the container, maintained for 10 minutes as it was, and then cooled to 20 ° C. This was dried by a spray dryer GS31 (manufactured by Yamato Kagaku) at a hot air temperature of 80 ° C. and an outlet temperature of 50 ° C. to obtain a toner.

Subsequent operations were performed in exactly the same manner as in Example 1, toner and developer were obtained, chargeability evaluation and image evaluation were performed, and the results are summarized in a table.

Example 4-2
A toner was obtained in the same manner as in Example 4-1, except that the treatment temperature was changed to 70 ° C. The developer was prepared in the same manner as in Example 1, and chargeability evaluation and image evaluation were performed and the results are summarized in a table.

Comparative Example 3
A three-roll kneader comprising mixing 100 parts by weight of polyester resin used in Example 1, 3 parts by weight of copper phthalocyanine pigment, 3 parts by weight of zinc di-t-butylsalicylate, and 2 parts by weight of NX-VP434. The mixture was heated and kneaded and dispersed by cooling, and after cooling, the kneaded product was roughly pulverized. The obtained coarsely pulverized product was pulverized by a jet mill.

Thereafter, the fine particle portion was removed with an air classifier, and 100 parts by weight of the obtained powder and 0.8 part by weight of hydrophobic silica were mixed with a mixer to obtain a toner.

The developer was prepared in the same manner as in Example 1, and chargeability evaluation and image evaluation were performed and the results are summarized in a table.

For this toner, a charge control agent 10 times as much as the toner of Example 4 is used.

Example 5
Two rolls prepared by mixing 100 parts by weight of partially crosslinked styrene-n-butyl methacrylate copolymer (softening point: 75 ° C.), 10 parts by weight of carbon black, and 5 parts by weight of low molecular weight polypropylene. After kneading and dispersing with a kneading apparatus and cooling, the kneaded product was coarsely pulverized. The obtained coarsely pulverized product is pulverized by a jet mill, the fine particle portion is removed by an air classifier, and 100 parts by weight of the obtained powder and 0.5 parts by weight of hydrophobic silica R972 are mixed with a mixer. As a result, primary particles were obtained.

25 parts by weight of primary particles were added to 100 parts by weight of ion-exchanged water having a concentration of 0.5% by weight of partially saponified polyvinyl alcohol while stirring, and stirring was continued for 10 minutes.

After 10 minutes, it was visually confirmed that the primary particles were completely wetted with the aqueous solution, and it was also confirmed by an optical microscope that the primary particles were separated and dispersed. Further, 20 parts by weight of a mixed solvent of ion exchange water and methyl ethyl ketone in a weight ratio of 4: 1 was gradually added with stirring.

Separately, 0.3 part by weight of Bontron S-34 (manufactured by Orient Chemical Co., Ltd.) was added to 20 parts by weight of methanol and dissolved. The solution was added to the primary particle dispersion described above and stirred, and heated with warm water from the outside of the container to increase the internal temperature to 80 ° C., maintained for 10 minutes, and then cooled to 20 ° C.

After the spheronization treatment, the dispersion was passed through a 400-mesh sieve and passed through the entire volume, and no agglomerates were found. The obtained dispersion is purified by repeating the operation of centrifugal sedimentation, removing the supernatant, and redispersing with the same amount of ion-exchanged water as the removed supernatant three times. After suction filtration, in an oven at 40 ° C. The drying process was carried out until a constant weight was reached. The toner of the present invention was obtained by crushing the obtained powder with a mixer.

Further, the developer was prepared in the same manner as in Example 1, and the chargeability evaluation and image evaluation were performed, and the results were summarized in a table. In addition, the saturation charge amount of the base particles before mixing when making the primary particles with the carrier used was −12 μC / g, and the chargeability with the hydrophobic silica R972 alone was measured. Polar charge amount was shown.

Comparative Example 4
All powders consisting of 100 parts by weight of the resin used in Example 5, 10 parts by weight of carbon black, 5 parts by weight of low molecular weight polypropylene and 3 parts by weight of Bontron S-34 (manufactured by Orient Chemical Industry Co., Ltd.) were mixed. After kneading and dispersing with a roll kneader and cooling, the kneaded product was coarsely pulverized.

The obtained coarsely pulverized product is pulverized by a jet mill, the fine particle portion is removed by an air classifier, and 100 parts by weight of the obtained powder and 0.5 part by weight of hydrophobic silica R972 are mixed by a mixer to obtain a toner. Obtained. Further, the developer was prepared in the same manner as in Example 1, and the chargeability evaluation and image evaluation were performed, and the results were summarized in a table.

This toner uses 10 times as much charge control agent as the toner of Example 5.

Example 6
When primary particles were produced, kneading treatment was performed in the same manner as in Example 5 except that 3 parts by weight of hydrophobized titanium oxide was added, followed by pulverization and classification. Primary particles were obtained by mixing 100 parts by weight of the obtained powder and 0.5 parts by weight of hydrophobic silica using a mixer. In Example 5 and Example 6 in the pulverization step, the supply rate of the coarsely pulverized product after kneading to give the same volume average particle size (the target pulverization size is 7.5 μm) was measured.

As a result, the result of Example 6 was about 2.5 times more than that of Example 5.

Using these primary particles, Example 5 and the subsequent treatment were carried out in exactly the same manner, toner and developer were obtained, chargeability evaluation and image evaluation were performed, and the results are summarized in a table.

Comparative Example 5
Primary particles were made in the same manner as in Example 5. However, as the primary particles, those whose surfaces were treated with an amino group-containing silane coupling agent as silica for mixing after pulverization classification were used. Subsequent steps were performed in exactly the same manner as in Example 5 to obtain a toner and a developer. However, when the dispersion was passed through a 400-mesh sieve after the spheronization treatment, unlike Example 5, clogging due to aggregates occurred, and the amount of aggregates reached 35% by weight with respect to the primary particles.

In addition, the chargeability of the carrier used and the hydrophobic silica alone treated with the amino group-containing silane coupling agent used in making the primary particles was measured, and the charge amount of the opposite polarity to the base particles was +65 μC / g. Indicated.

In addition, the image evaluation and the running test of 10,000 sheets are Examples 1, 2-1, 2-2, 3-1, 3-2, 4-1, 4-2, and Comparative Examples 1, 2, and 3 are respectively Ricoh. Examples 6 and 7 and Comparative Examples 4 and 5 were evaluated by Ricoh's digital copier Imagio DA-250, using a full color copier pre-tail 550.

It is a figure which shows the continuous flow process of the toner apparatus of this invention.

Claims (2)

In an electrophotographic toner comprising at least a resin, a colorant, and a charge control agent, the toner is a toner in which a charge control agent is adhered to the surface in a liquid and is saturated when mixed and stirred with a carrier coated with a silicon resin. An electrophotographic toner having an absolute charge amount of 10 to 40 μC / g and a carrier contamination degree of 20% or less. 2. The electrophotographic toner according to claim 1, wherein the toner does not contain a charge control agent other than in the vicinity of the particle surface.

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