JP3775125B2 - Method for producing color toner for electrophotography - Google Patents

Description

【００６９】
キャリア
ポリエステル樹脂（バイロン２００；東洋紡社製）をトルエン、イソプロパノールの混合溶媒に溶解し、平均径４０μｍの焼成フェライト粉（Ｆ３００；パウダーテック社製）にスピラコータ（岡田精工社製）で塗布、乾燥した。オーブン中１４０℃、２時間焼成後、解砕、フルイを行い、平均径４２μｍのポリエステル樹脂コートのフェライトキャリアを調製した。
【００７０】
【発明の効果】
本発明により、トナーの帯電立ち上がり性および帯電安定性が向上し、画像濃度の低下、キメの悪化およびカブリの発生を長期にわたって防止できるという優れた効果が得られる。
【図面の簡単な説明】
【図１】 帯電量の測定に用いた帯電量測定装置の概略構成図を示す。
【符号の説明】
１：円筒電極、２：導電性スリーブ、３：磁性ロール、４：バイアス電源、５：測定用コンデンサ、６：現像剤、７：分離トナー。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic color toner and a method for producing the same.
[0002]
[Prior art]
As color electrophotographic copying machines and printers are widely spread, high quality images having graininess (texture) and resolution close to that of photographic printing are required, and the diameter of toner has been reduced in recent years. However, generally, the smaller the toner diameter, the higher the charge amount per unit weight and the worse the developability, so it is difficult to maintain and reproduce a stable image for a long period of time. For this reason, in designing the developer, it is necessary to control the charge amount level according to the toner composition, the particle shape, etc., and to devise a sharp charge amount distribution.
[0003]
As a toner manufacturing method, a so-called pulverization method is generally used in which a resin, a pigment, or the like is mechanically kneaded and then pulverized. However, the smaller the particle size of the toner obtained by the pulverization method, the more complicated the equipment steps for obtaining the desired toner, and the higher the cost, as well as the irregular shape due to pulverization, and When the toner surface has a lot of irregularities and is subjected to mechanical stress, it has a drawback that toner fine particles are easily generated. In the case of a small diameter toner having an average particle diameter of 10 μm or less, there are many toner fine powders of several μm, and since the fine powder has strong adhesive force, it adheres to the concave portions of the carrier and the charge imparting member, causing fluctuations in the charge amount of the toner, There was a problem that the image quality deteriorated. In particular, in the production of color toners using soft resins with low molecular weight to give gloss, from the viewpoint of durability, toner fine particles and the components contained therein fall off due to mechanical stress in the developing device, and carrier and It is required to prevent the transfer to a charging member or the like.
[0004]
On the other hand, as a method for producing a toner suitable for reducing the diameter, an oily phase obtained by dissolving and dispersing a binder resin or a monomer capable of forming the binder resin, a colorant, and a desired additive such as a charge control agent is added to the aqueous phase. Many methods such as an emulsification dispersion method, an emulsion polymerization method, a suspension polymerization method, and the like, which are added to the mixture and granulated have been proposed. However, although toners produced by these wet methods can suppress the generation of fine powders, they are generally difficult to be frictionally charged due to their spherical shape, and have a drawback of poor charge rise. In addition, it is necessary to reduce the drop-out / transfer of the charge control agent that easily causes fluctuations in the charge amount when the toner component is contaminated. In view of the above, in a color toner having a small diameter by a wet method, there is a problem of how to disperse the charge control agent on the toner surface without dropping off from the viewpoint of charging performance and contamination resistance. However, when a charge control agent is added internally together with other toner components before granulation as conventionally performed in both the pulverization method and the wet method, it is difficult to make the charge control agent effectively exist on the toner surface.
[0005]
In order to overcome the above problems, the following studies have been made. In JP-A-7-199535, charging is performed by adding and granulating an oily phase containing a polymerizable monomer, a polymerization initiator and a colorant in an aqueous phase in which a charge control agent is dispersed in a polymerization toner forming method. Attempts have been made to improve the charging performance by uniformly fixing the control agent on the surface of the toner particles. The toner thus obtained has excellent chargeability at the initial stage because a charge control agent is present on the surface. However, the metal complex charge control agent used here is difficult to finely disperse in the aqueous phase, and the particle size of the charge control agent present on the toner surface is larger than those obtained by the pulverization method or the conventional oil phase addition method. Therefore, it tends to fall off in the developing device, contaminates the carrier and the charge imparting member, and tends to lower the charging performance during durability. When the charging performance is lowered, the image density is changed, the texture is deteriorated on the obtained image, or the fog is generated. On the other hand, when a charge control agent that is easily dispersed in an aqueous phase is used, there is a problem that the amount of charge fluctuation in a high and low humidity environment increases.
[0006]
JP-A-6-234863 discloses a technique in which solid particles of a toner granulated by a wet method and charge control agent fine particles are dispersed in water or a water / alcohol mixed solvent, and the fine particles are fixed to the toner surface by mechanical shearing. Has been reported. However, the charge control agents that can be finely dispersed by the solvent used here are limited, and most of them can be dissolved. As a result, even if mechanical shear is applied, the particle size of the charge control agent particles present on the surface is large, which is not preferable from the viewpoint of a decrease in charging performance due to contamination of the carrier and the charge imparting member. Further, since a surface modification step is required, the manufacturing cost is increased.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and provides an electrophotographic color toner that is excellent in charge rise property and charge stability, and prevents deterioration of image density, deterioration of texture, and fogging over a long period of time, and a method for producing the same. The purpose is to provide.
[0008]
[Means for Solving the Problems]
  The present inventionForming liquid particles composed of an oily phase formed by dissolving and dispersing at least a binder resin and a colorant in an organic solvent capable of dissolving a charge control agent in the aqueous phase, and then removing the organic solvent from the liquid particles. A method for producing a color toner for electrophotography comprising: adding a charge control agent to a dispersion after forming liquid particles comprising an oily phase in an aqueous phase and before completing the removal of the organic solvent. Method for producing electrophotographic color tonerAbout.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
In the electrophotographic color toner of the present invention, the charge control agent has an average particle size of 0.15 μm or less, preferably 0.10 μm or less, more preferably 0.08 μm or less on the surface of toner particles comprising at least a binder resin and a colorant. It exists in. In the present invention, the charge control agent is present on the surface of the toner particles with such a small particle size, and the fall of the charge control agent is suppressed, so that the charge rising property and charge stability are improved, the image density is reduced, It is possible to effectively prevent the deterioration of texture and the occurrence of fogging over a long period of time. If the average particle size of the charge control agent present on the toner particle surface exceeds 0.15 μm, the charge control agent will fall off significantly during repeated copying. This causes problems such as deterioration of fog and occurrence of fog.
[0011]
The amount of the charge control agent present on the toner particle surface is generally 0.02 to 1 part by weight, preferably 0.05 to 0.5 part by weight, based on 100 parts by weight of the binder resin.
[0012]
In the present invention, the charge control agent is preferably fixed to the toner particle surface. The sticking further suppresses the dropping of the charge control agent, so that the charging stability is further improved. More preferably, the charge control agent is fixed to the toner particles at a depth (embedding depth in the toner particles) of 1/4 to 4/4, preferably 2/4 to 3/4, of the particle size of the charge control agent. ing. The fixing means that at least a part of the charge control agent particles are buried in the toner particles and the charge control agent is fixed to the toner particles.
[0013]
In the present specification, the average particle size of the charge control agent present on the toner particle surface is the average value of the charge control agent particle size (maximum length) measured by observing the particle surface with an electron microscope (magnification 150,000 times). Is used. When the charge control agent is fixed to the surface of the toner particles, the average particle diameter refers to the apparent average particle diameter of the charge control agent. The apparent average particle diameter of the charge control agent refers to the average value of the diameter (maximum length) of the contour indicated by the non-buried portion of the charge control agent when the charge control agent partially buried is viewed from the front. .
[0014]
The color toner of the present invention is a wet process that does not include a polymerization process, or a wet process that includes a polymerization process. In any wet process, at least a binder resin or a monomer that can form a binder resin, and a colorant are charged. After the liquid particles composed of the oily phase formed by dissolving and dispersing in the organic solvent capable of dissolving the agent are formed in the aqueous phase, before the removal of the organic solvent is completed, the charge control agent is dispersed in the liquid particles. It can be obtained by adding to the dispersion. In this way, an organic solvent capable of dissolving the charge control agent is added to the oily phase containing the toner component in the wet method, and the oily phase is mixed and stirred in the aqueous phase containing the dispersant. After the formation of the liquid particles (emulsion) and before the removal of the organic solvent is completed, the charge control agent is added to the dispersion system in which the liquid particles are dispersed, so that the charge control agent is reduced on the toner particle surfaces. Toner present in particle size can be obtained.
[0015]
The color toner of the present invention that can be manufactured by such a wet method can suppress the generation of fine powder and can be manufactured at a low cost even with a small particle size. In addition, since the toner particles obtained by the wet method have a substantially spherical shape and there are few irregularities on the surface of the particles, generation of toner fines due to mechanical stress in the actual machine can be avoided.
[0016]
Preferably, a wet method that does not include a polymerization process, for example, an emulsion dispersion method is employed. When the emulsification dispersion method is employed, the color toner of the present invention specifically includes liquid particles comprising an oily phase obtained by dissolving and dispersing at least a binder resin and a colorant in an organic solvent capable of dissolving a charge control agent. A method for producing a color toner for electrophotography, which comprises removing an organic solvent from a dispersion in which liquid particles are dispersed, wherein the liquid particles are dispersed in an aqueous phase. After being formed therein, before the removal of the organic solvent is completed, it can be produced by a method for producing a color toner for electrophotography, which is added to a dispersion composed of liquid particles in an aqueous phase.
[0017]
Specifically, first, at least a binder resin and a colorant are dissolved and dispersed in an organic solvent capable of dissolving a charge control agent to prepare an oily phase.
[0018]
As the binder resin, any known resin that can be used in the field of color toner for electrophotography can be used. For example, polyester resin, styrene resin, (meth) acrylic resin, styrene- (meth) acrylic resin Examples thereof include a copolymer resin, an olefin resin, a polyamide resin, a polycarbonate resin, a polyether resin, a polyvinyl acetate resin, a polysulfone resin, an epoxy resin, a polyurethane resin, and a urea resin. One or more of the above resins may be used. A polyester resin is preferably used as the main component resin from the standpoint of fixing properties as a binder resin for color toners.
[0019]
Any known pigment / dye can be used as the colorant.
Examples of the black pigment include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, magnetic ferrite, and magnetite.
Examples of the yellow pigment include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, minerfast yellow, nickel titanium yellow, and benzidine yellow G.
Examples of the orange pigment include red chrome yellow, molybdenum orange, permanent orange GTR, parazolone orange, and vulcan orange.
[0020]
Examples of red pigments include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, lysole red, pyrazolone red, watch red, calcium salt, lake red C, lake red D, and brilliant carmine 6B. Can be mentioned.
Examples of blue pigments include bitumen, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, and phthalocyanine blue.
Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white.
These colorants can be used alone or in combination.
[0021]
The colorant is usually used in an amount of 1 to 20 parts by weight, preferably 2 to 15 parts by weight, based on 100 parts by weight of the binder resin. When using in combination of 2 or more types, the total amount should just be in the said range.
[0022]
If desired, a known toner component other than the charge control agent, for example, a release material, magnetic powder or the like may be dissolved or dispersed in the oil phase.
[0023]
As the release material, known release materials can be used. For example, olefin wax such as polyethylene and polypropylene, montan wax such as ester, acid, and montan wax, plant wax such as carnauba, wax, and jojoba, and fat. Aliphatic alcohols, fatty acids, aliphatic metal salts, silicone compounds and the like. The release material is usually used in an amount of 1 to 15 parts by weight, preferably 2 to 10 parts by weight, based on 100 parts by weight of the binder resin.
[0024]
As the magnetic powder, known magnetic powder can be used, and examples thereof include alloys such as iron, nickel, and copper, oxides, ferrite, and magnetite. The magnetic powder is usually used in an amount of 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the binder resin.
[0025]
In the present invention, an organic solvent capable of dissolving a charge control agent used in a later step is used as the organic solvent in which the toner component as described above is dissolved or dispersed. Such an organic solvent depends on the charge control agent used in the subsequent step, and examples thereof include known aromatic solvents, ester solvents, ketone solvents, alcohol solvents, and halogen solvents. Specific examples of these aromatic solvents include toluene and xylene. Examples of the ester solvent include ethyl acetate and butyl acetate. Examples of the ketone solvent include acetone and methyl ethyl ketone. Examples of the alcohol solvent include isopropyl alcohol, n-butanol, ethanol and the like. Examples of the halogen solvent include chloroform and carbon tetrachloride. You may use the said organic solvent individually or in combination of 2 or more types. The amount of the organic solvent used is not particularly limited as long as it does not adversely affect the dispersibility of the oily phase in the aqueous phase, and is generally preferably 50 to 95% by weight based on the total weight of the oily phase.
[0026]
In this specification, “an organic solvent capable of dissolving a charge control agent” means that the charge control agent used is 100 g (25 ° C.) of an organic solvent (a mixed organic solvent when used in combination of two or more). It means that 3 g or more, preferably 9 g or more can be dissolved. When the amount of the charge control agent dissolved in the organic solvent is small, a toner in which the charge control agent is finely dispersed on the toner surface as described above cannot be obtained.
[0027]
Next, the obtained oily phase is dispersed in the aqueous phase to prepare a dispersion system (O / W emulsion) in which liquid particles comprising the oily phase are dispersed in the aqueous phase.
[0028]
The aqueous phase is formed by adding additives such as a dispersant and / or a dispersion aid to water. As the dispersant, those that become a hydrophilic colloid in an aqueous dispersant are preferable. In particular, gelatin, gum arabic, agar, cellulose derivatives (eg, hydroxymethylcellulose, hydroxyethylcellulose, etc.), synthetic polymers (eg, polyvinyl alcohol, polyvinylpyrrolidone). , Polyacrylates (sodium polyacrylate, etc.), polymethacrylates, etc.), sparingly soluble inorganic salts (eg, calcium phosphate, etc.), hydrophilic silica and the like.
[0029]
As the dispersion aid, a surfactant is usually used, and a natural surfactant such as aponin, a nonionic surfactant such as alkylene oxide, glycerin or glycidol, carboxylic acid, sulfonic acid, phosphoric acid, sulfate ester An anionic surfactant containing an acidic group such as a group or a phosphate group.
[0030]
The concentration of the dispersant and the dispersion aid in the aqueous phase is not particularly limited and is selected within a range that can be employed in a known emulsification dispersion method, and is generally 0.1 to 10% by weight and 0.001 to 2% by weight, respectively. Is preferred.
[0031]
In dispersing the oily phase in the aqueous phase, it is preferable to control the diameter of the liquid particles in the oily phase by stirring so that the toner particles obtained have a desired particle size. The mixing volume ratio between the oily phase and the aqueous phase (oily phase / aqueous phase) is not particularly limited as long as the liquid particles composed of the oily phase can be dispersed in the aqueous phase, but from the viewpoint of ease of formation of the liquid particles and their stability. (Normal) 1 or less is preferable.
[0032]
After preparing the dispersion, a charge control agent is added to the dispersion before the removal of the organic solvent is completed. That is, the charge control agent may be added to the system immediately after the dispersion is prepared, or may be added to the system after the dispersion is prepared and during the removal of the organic solvent. For example, in the case where the organic solvent is removed over 20 hours from immediately after preparation of the dispersion, the charge control agent is preferably added within 15 hours from immediately after preparation of the dispersion, and more preferably, preparation of the dispersion. It is added immediately after 10 hours and more preferably immediately after the preparation of the dispersion and 5 hours.
[0033]
After the dispersion system is prepared, that is, after forming the oily phase liquid particles in the aqueous phase and before the removal of the organic solvent is completed, the charge control agent is brought into contact with the liquid particles when added to the system. When adsorbed on the liquid particles and dissolved on the particle surface by the organic solvent in the liquid particles, the charge control agent is uniformly distributed on the toner particle surface when the solvent is removed from the dispersion and the particles are solidified. It is thought that it precipitates in a finely dispersed state. If the charge control agent is added to the aqueous phase before the preparation of the dispersion, the charge control agent is taken into the liquid particles composed of the oil phase during the preparation of the dispersion and is not dissolved on the surface of the liquid particles. However, the charge control agent hardly deposits on the toner particle surface. On the other hand, if the charge control agent is added after the removal of the organic solvent is completed, the charge control agent is not dissolved on the surface of the liquid particles, so that a toner in which the charge control agent is uniformly finely dispersed on the surface cannot be obtained.
[0034]
The average particle size after the deposition of the charge control agent is determined by appropriately selecting various conditions such as the solubility of the charge control agent in the organic solvent, the removal rate of the organic solvent, and the addition timing of the charge control agent. It can be controlled along with the size of the particles. That is, the larger the solubility of the charge control agent in the organic solvent, the smaller the average particle diameter of the charge control agent. This is because the higher the solubility, the easier the charge control agent dissolves on the surface of the liquid particles, and therefore, the probability that the large-size charge control agent remaining undissolved on the surface of the obtained toner particles is reduced. The average particle size of the charge control agent is smaller as the organic solvent removal rate is larger. This is because crystal nuclei for crystal growth are generally difficult to form as the removal rate of the organic solvent increases. Further, the earlier the timing of addition of the charge control agent to the dispersion within the above range, the smaller the average particle size of the charge control agent. This is because the charge control agent is sufficiently dissolved in the organic solvent in the liquid particles, and the probability that there is a large-diameter charge control agent remaining undissolved on the surface of the obtained toner particles is reduced.
[0035]
Further, by appropriately selecting the timing of addition of the charge control agent to the dispersion within the above range, the charge control agent existing depth from the toner surface (embedding depth in the toner particles) and its amount can be controlled. Can do. The solidification by removing the organic solvent from the liquid particles in the oil phase occurs from the inside of the liquid particles, so the earlier the addition timing, the greater the depth of the charge control agent, and the charge control agent adheres more firmly to the toner particles. At the same time, the toner content increases.
[0036]
The charge control agent (CCA) used in the present invention is not particularly limited as long as it can be dissolved in the organic solvent used in the oily phase, and is positive or negative due to frictional charging conventionally used in the field of electrophotography. Any known negative charge control agent and positive charge control agent capable of providing the following charge can be used. Further, from the viewpoint of colorization, a transparent to white charge control agent that does not impair the color tone of the color toner is preferable, and in the present invention, in order to suppress fluctuations in the charge amount of the toner under high and low humidity environments as much as possible. A charge control agent that hardly adsorbs and desorbs moisture, that is, hardly soluble in water, is more preferable.
[0037]
Examples of the negative charge control agent include metal-containing complex salts Bontron E81 and E84 (manufactured by Orient Chemical), LR147 (manufactured by Nippon Carlit), thioindigo pigment, calixarene compound Bontron E89 (manufactured by Orient Chemical), and fluorine-containing compounds. Compound copy charge NX VP434 (made by Hoechst), FT-310 (made by Neos), etc. are mentioned. Examples of the positive charge control agent include quaternary ammonium salt P-51 (manufactured by Orient Chemical Co.), copy charge PX VP435 (manufactured by Hoechst), and the like. One or more of these may be used.
[0038]
The charge control agent is preferably used after being pulverized to an average particle size of 100 μm or less, preferably 50 μm or less, from the viewpoint of ease of dissolution in the organic solvent in the oily phase.
[0039]
The amount of the charge control agent added to the dispersion is not particularly limited, but is preferably 0.1 to 4 parts by weight with respect to 100 parts by weight of the aqueous phase used previously.
[0040]
The removal of the organic solvent is carried out by heating or depressurizing and evaporating the dispersion. In general, it is preferable to remove the organic solvent in the liquid particles dispersed in the aqueous phase below the glass transition point of the binder resin in the oily phase so that the particles do not aggregate. The heating time and the degree of reduced pressure can be appropriately selected depending on the type of organic solvent (boiling point, etc.), the amount of organic solvent used, and the like. Specifically, for example, when 360 g of toluene / methyl ethyl ketone (8/2) is used as an organic solvent to remove the organic solvent at normal pressure, the organic solvent is removed at 35 to 55 ° C. over 10 to 70 hours. It is preferable to remove.
[0041]
After the removal of the organic solvent is completed, the toner of the present invention can be obtained by cooling, repeating filtration / washing several times, drying and crushing.
[0042]
The color toner of the present invention may be obtained by employing a wet method including a polymerization process, for example, a suspension polymerization method, an emulsion polymerization method, an emulsion polymerization aggregation method, a seed polymerization method, an interfacial polymerization method and the like. Hereinafter, the case where the suspension polymerization method is employed to obtain the color toner of the present invention will be described. However, unless otherwise specified, the same method as in the case where the above emulsion dispersion method is employed is used.
[0043]
In the case of employing the suspension polymerization method, the color toner of the present invention is more specifically an oily material obtained by dissolving and dispersing at least a monomer capable of forming a binder resin and a colorant in an organic solvent capable of dissolving a charge control agent. A method for producing a color toner for electrophotography comprising forming liquid particles comprising a phase in an aqueous phase, then polymerizing a monomer and removing an organic solvent from the liquid particles, wherein the charge control agent is applied from the oily phase. After the liquid particles to be formed in the aqueous phase are added to the dispersion before the removal of the organic solvent is completed, the liquid particles can be produced by a method for producing an electrophotographic color toner.
[0044]
Specifically, first, an oily phase is prepared by dissolving and dispersing at least a monomer capable of forming a binder resin and a colorant in an organic solvent capable of dissolving a charge control agent.
[0045]
Examples of monomers that can form a binder resin include all monomers that can be used as raw materials for the styrene resin, (meth) acrylic resin, styrene- (meth) acrylic copolymer resin, and the like, such as vinyl monomers. Can be used.
[0046]
The oily phase preferably contains a known radical polymerization initiator such as an azo compound polymerization initiator, a hydroperoxide polymerization initiator, or a redox polymerization initiator.
If desired, a known toner component other than the charge control agent, for example, a release material, magnetic powder or the like may be dissolved or dispersed in the oil phase.
[0047]
The organic solvent capable of dissolving the charge control agent is desirably 5% by weight or more based on the total weight of the oily phase as long as it does not adversely affect the dispersibility of the oily phase in the aqueous phase and the polymerization of the monomer.
[0048]
Next, the obtained oily phase is dispersed in the aqueous phase to prepare a dispersion system in which liquid particles composed of the oily phase are dispersed in the aqueous phase. After preparing the dispersion, a charge control agent is added to the dispersion before the removal of the organic solvent is completed. That is, the charge control agent may be added to the system immediately after the dispersion is prepared, or after the dispersion is prepared and added to the system while the monomer is polymerized and the organic solvent is removed. May be.
[0049]
The organic solvent is removed by heating the dispersion. After the removal of the organic solvent is completed, the toner of the present invention can be obtained by cooling, repeating filtration / washing several times, drying and crushing.
[0050]
In the case of employing the suspension polymerization method, the organic solvent may not be used as long as the charge control agent can be dissolved in the monomer. At this time, the amount of charge control agent dissolved in the monomer (100 g, 25 ° C.) may be within the range of the amount of charge control agent dissolved in the organic solvent.
[0051]
At this time, in detail, the color toner of the present invention specifically polymerizes the monomer after forming in the aqueous phase liquid particles composed of an oily phase formed by mixing at least a monomer capable of forming a binder resin and a colorant. A method for producing a color toner for electrophotography, comprising: adding a charge control agent to a dispersion after forming liquid particles composed of an oily phase in an aqueous phase and before completing the polymerization of monomers. It can be manufactured by a method for manufacturing a color toner for electrophotography. The charge control agent may be added to the system immediately after the oily phase is dispersed in the aqueous phase, or may be added to the system during the polymerization of the monomer after the oily phase is dispersed in the aqueous phase. May be.
[0052]
Further, when the color toner of the present invention is obtained by adopting a “wet method including a polymerization process” other than the suspension polymerization method, the oily phase contains an organic solvent capable of dissolving the charge control agent, If the addition to the system is carried out after the preparation of the dispersion and before the removal of the organic solvent is completed, each known wet method is followed. Note that the case where the charge control agent can be dissolved in the monomer corresponds to the case where the charge control agent in the case of employing the above suspension polymerization method can be dissolved in the monomer.
[0053]
The color toner of the present invention that can be produced by the above production method is desirably controlled to have a volume average particle size of 10 μm or less, preferably 4 to 9 μm.
[0054]
The color toner of the present invention is preferably surface-treated with fine particles from the viewpoint of improving fluidity, chargeability, heat resistance and the like. As the fine particle material, conventionally known fine particle materials externally added to toner in the field of electrophotography can be used, and examples thereof include metal oxides, intermetallic compounds, and resins. Specific examples of the metal oxide include silica, titanium oxide, alumina, and zirconia. Examples of the intermetallic compound include strontium titanate, silicon carbide, silicon nitride, and the like. Examples of the resin include a polymer fluoride, a silicone compound, an acrylic resin, and the like.
[0055]
The toner of the present invention can be used as a two-component developing toner used with a carrier or as a one-component developing toner not using a carrier.
[0056]
As the carrier used with the color toner of the present invention, a known carrier can be used. For example, a carrier made of magnetic particles such as iron powder and ferrite, and a coated type in which the surface of the magnetic particles is coated with a coating agent such as a resin. Either a carrier or a dispersion type carrier in which magnetic fine powder is dispersed in a binder resin can be used.
Hereinafter, the present invention will be described in more detail with reference to examples.
[0057]
【Example】
(Example 1)
After 100 g of a polyester resin (NE-382; manufactured by Kao Corporation) was dissolved in 360 g of a mixed solvent of toluene / methyl ethyl ketone (8/2), the obtained resin solution was placed in a 2 liter plastic bottle together with 5 g of phthalocyanine pigment, and Ultra Turrax (IKA). For 30 minutes to obtain a homogeneous mixed oily phase. Next, 10 g of sodium alkyldiphenyl ether disulfonate is added to 1000 g of a 3.5 wt% sodium polyacrylate aqueous solution to form an aqueous phase, which is mixed into the oily phase. The rotation speed of K auto homomixer (made by Tokushu Kika Kogyo Co., Ltd.) was set to 3500 rpm, and the mixture was stirred for 10 minutes for emulsification. Immediately after, 10 g of LR147 (manufactured by Nippon Carlit Co., Ltd.) was added as a charge control agent to the emulsion, and the mixture was further stirred for 1 minute. Thereafter, the mixture was stirred with a three-one motor in a thermostatic bath at 50 ° C. to 55 ° C. for 20 hours while adding water as appropriate to remove toluene / methyl ethyl ketone, and after cooling, filtration / washing was repeated several times. The washed toner cake is transferred to a stainless steel vat, dried at 35 ° C. for 48 hours in a constant temperature dryer, crushed using a ball mill, sieved with a 90 μm mesh, and toner particles having an average diameter of 7.2 μm are obtained. Obtained. As a result of observation with an electron microscope (150,000 times), the average particle diameter of the charge control agent particles deposited on the surface of the toner particles was about 0.05 μm. It was confirmed by detecting the metal contained in the charge control agent with an X-ray microanalyzer that the particles were a charge control agent. The amount of the charge control agent dissolved in toluene / methyl ethyl ketone (8/2) (100 g, 25 ° C.) was about 10 g.
[0058]
(Example 2)
In the same manner as in Example 1, the aqueous phase was mixed into the oily phase and emulsified. Next, the emulsion was stirred for 10 hours with a three-one motor in a thermostatic bath at 50 ° C. to 55 ° C. while appropriately adding water, and then 10 g of LR147 (manufactured by Nippon Carlit) was added to the emulsion as a charge control agent. Toluene / methyl ethyl ketone was removed by stirring for 10 hours while adding water appropriately. Thereafter, in the same manner as in Example 1, cooling, washing, drying and crushing were performed to obtain toner particles having an average diameter of 7.5 μm. When the surface of the toner particle was observed with an electron microscope and analyzed in the same manner as in Example 1, the average particle diameter of the charge control agent particles deposited on the toner surface was about 0.07 μm.
[0059]
(Example 3)
T.A. The rotation speed of the K auto homomixer was set to 4500 rpm, 20 g of metal-containing complex salt E84 (manufactured by Orient Chemical Co., Ltd.) was used instead of 10 g of LR147 as the charge control agent, and toluene solvent was used instead of the toluene / methyl ethyl ketone mixed solvent. Except for the use, toner particles having an average particle diameter of 5.4 μm were obtained in the same manner as in Example 1. When the surface of the toner particles was observed and analyzed in the same manner as in Example 1, the average particle size of the charge control agent particles deposited on the toner surface was about 0.08 μm. The amount of the charge control agent dissolved in toluene (100 g, 25 ° C.) was about 35 g.
[0060]
(Comparative Example 1)
In Example 1, after emulsification, the toluene / methyl ethyl ketone mixed solvent was dissolved without adding the charge control agent, and filtration / washing was performed. 50 g of the washed toner cake was added to 1000 g of a water / methanol (9/1) mixed solvent in which 10 g of the charge control agent LR147 used in Example 1 was dispersed. The surface of the toner surface was modified with a charge control agent by stirring for 5 minutes at a rotation speed of 7000 rpm of a K auto homomixer. Thereafter, filtration, drying and crushing were performed to obtain toner particles having an average particle diameter of 7.8 μm. When the surface of the toner particles was observed with an electron microscope and analyzed in the same manner as in Example 1, the average particle size of the charge control agent particles deposited on the toner surface was about 0.20 μm.
[0061]
(Comparative Example 2)
In Example 3, after emulsification, the toluene solvent was removed without adding the charge control agent, and the process up to filtration / washing was performed. 50 g of the toner cake after washing with water was added to 1000 g of a water / isopropyl alcohol (9/1) mixed solvent in which 20 g of the charge control agent E84 used in Example 3 was dispersed. The surface of the toner surface was modified with a charge control agent by stirring for 5 minutes at a rotation speed of 7000 rpm of a K auto homomixer. Thereafter, filtration, drying and crushing were performed to obtain toner particles having an average particle diameter of 5.7 μm. When the surface of the toner particles was observed with an electron microscope and analyzed in the same manner as in Example 1, the average particle size of the charge control agent particles deposited on the toner surface was about 0.55 μm.
[0062]
(Comparative Example 3)
Toner particles having an average particle diameter of 7.5 μm were obtained in the same manner as in Example 1 except that a toluene solvent was used instead of the toluene / methyl ethyl ketone mixed solvent. When the surface of the toner particles was observed with an electron microscope and analyzed in the same manner as in Example 1, the average particle size of the charge control agent particles deposited on the toner surface was about 1.5 μm. The amount of the charge control agent dissolved in toluene (100 g, 25 ° C.) was about 1.5 g.
[0063]
1.2 parts by weight of silica fine particles (R972; manufactured by Nippon Aerosil Co., Ltd.) are added to 100 parts by weight of the toner particles obtained in the above Examples and Comparative Examples, and 30 m / s is added using a Henschel mixer (Mitsui Metal Mining Co., Ltd.). The toner was surface-treated by mixing at a speed for 3 minutes. This toner and the following carrier were mixed at a toner mixing ratio of 6 wt% to obtain a two-component non-magnetic developer, and the charge amount and image quality at the initial stage of the actual machine durability test and 10,000 copies were evaluated. The actual machine used was a full color electrophotographic copying machine CF900 (manufactured by Minolta).
[0064]
Charge measurement
In the electric field separation type charge amount measuring apparatus shown in FIG. 1, the developer 2g is coated on the sleeve 2, -2 kv is applied to the sleeve 2 by the bias power source 4, and the sleeve 2 is rotated at 1000 rpm for 1 minute to form the cylindrical electrode 1. Toner 7 was separated. The charge amount (μc / g) was calculated from the separated toner weight (g) and the charge amount (μc) flowing into the measuring capacitor 5 at the time of toner separation.
[0065]
Image quality evaluation
The transition of image density, graininess, and background fog was evaluated.
(Image density)
The density of arbitrary 10 points in the solid copy image with the maximum density by CF900 was measured with a Macbeth densitometer (manufactured by Macbeth Co.), and an average value x thereof was obtained and evaluated according to the following.
○: 1.0 <x <1.3
Δ: 0.8 <x ≦ 1.0 or 1.3 ≦ x <1.5
X: x ≦ 0.8 or 1.5 ≦ x
[0066]
(Granularity)
The copy image by CF900 was visually observed and evaluated according to the following ranking. Note that the granularity means the uniformity of a solid image with a low density (quality of texture).
○: Good, comparable to the manuscript;
Δ: Slightly inferior to the original, but no problem in practical use;
×: It is considerably inferior to the original and cannot be used practically.
[0067]
(Skin texture)
The copy image by CF900 was visually observed and evaluated according to the following ranking. The background fogging refers to a stain caused by toner generated by developing and transferring low-charge / reverse-charge toner on a copy sheet in addition to the original image portion.
○: Good with no difference from the color of the paper itself;
Δ: Although there is fog, there is no problem in practical use;
×: Fog is considerably generated and cannot be used practically.
[0068]
The evaluation results are shown below.
[Table 1]

[0069]
Career
A polyester resin (Byron 200; manufactured by Toyobo Co., Ltd.) was dissolved in a mixed solvent of toluene and isopropanol. After firing in an oven at 140 ° C. for 2 hours, crushing and sieving were carried out to prepare a polyester resin-coated ferrite carrier having an average diameter of 42 μm.
[0070]
【The invention's effect】
According to the present invention, it is possible to improve the charging start-up property and charging stability of the toner, and to obtain an excellent effect that it is possible to prevent deterioration of image density, deterioration of texture, and generation of fog over a long period of time.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a charge amount measuring apparatus used for measuring a charge amount.
[Explanation of symbols]
1: cylindrical electrode, 2: conductive sleeve, 3: magnetic roll, 4: bias power supply, 5: measuring capacitor, 6: developer, 7: separated toner.

Claims (3)

Forming liquid particles composed of an oily phase formed by dissolving and dispersing at least a binder resin and a colorant in an organic solvent capable of dissolving a charge control agent in the aqueous phase, and then removing the organic solvent from the liquid particles. A method for producing a color toner for electrophotography comprising: adding a charge control agent to a dispersion after forming liquid particles comprising an oily phase in an aqueous phase and before completing the removal of the organic solvent. A method for producing a color toner for electrophotography. The method for producing a color toner for electrophotography according to claim 1, wherein the binder resin is a polyester resin. The color toner for electrophotography in which the charge control agent is present on the surface of the toner particles containing at least a binder resin and a colorant with an average particle size of 0.15 μm or less is obtained. A method for producing a color toner for electrophotography .

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