JP2005345975A - Positive charge type toner, positive charge type developer and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive charge type toner which gives a toner image having stable line width and image quality, even in an image forming apparatus having a large mode differences, such as a color high-speed machine, and which does not cause image deletion, even if abrasive particles are not added to the toner, and to provide a positive charge type developer and an image forming method. <P>SOLUTION: The positive charge type toner contains a resin, a release agent and colored particles, wherein the cationic surfactant concentration of surfaces of toner particles is higher than that of central portions of the toner particles. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a positively charged toner, a positively charged developer, and an image forming method.

  In an electrophotographic image forming method, an electrostatic latent image formed on a photosensitive member is developed with toner to form an image, and the toner is negatively charged for stable image formation over a long period of time. Thus, a method of forming an image is mainly employed. By the way, when the image is formed by negatively charging the toner, it is difficult to completely eliminate the problem of ozone generation. In particular, in recent years, the size of the apparatus has been reduced, and opportunities for using devices such as printers and facsimiles in small offices and general homes have increased. Ozone gas emits odors, so even if the generated amount is low level that does not adversely affect the human body, it is unpleasant for the user. In image forming apparatuses, ozone countermeasures have been actively implemented for a long time. It was. A representative ozone countermeasure technique is an ozone filter. This is intended to prevent ozone discharge into the atmosphere by collecting the exhaust of the charger or the entire apparatus in one place and collecting it with an ozone filter (or decomposing with a catalyst) (for example, Non-Patent Document 1). reference.).

  However, the ozone filter cannot avoid the problem that the cost of the filter itself is high and the recovery performance decreases with time, and the ozone problem cannot be solved.

  On the other hand, an image forming technique using a positively charged toner that does not raise concern about the problem of ozone generation when forming an electrostatic latent image has also attracted attention. Among them, a technology for forming an image by using a chemical toner formed by drying after forming toner particles in an aqueous medium typified by polymerized toner as a positively charged toner is effective. In addition to the effect of preventing ozone generation, Since the toner can be manufactured while controlling the toner particle size and particle size distribution, it is possible to obtain a toner having a small diameter and a uniform size that can accurately reproduce a dot image in a digital system.

  In chemical toners, toner particles can be formed by adding wax, fixing aids, etc. at the time of toner production, so they can be encapsulated and surface modified with a resin layer, achieving both fixability and storage stability. can do.

  In addition, since the shape of the chemical toner can be controlled relatively easily, for example, a toner having a shape with a high transfer rate is manufactured and applied to a cleaner-less process type device, or the toner is controlled to a specific range of shape. Can be applied to the blade cleaning process, and can be applied to a high-speed machine with a large print volume.

  Furthermore, it is easy to align the toner in a specific shape or sharpen the particle size distribution, so it can be applied to image forming methods with a high charging speed, and image formation with a one-component developer, especially non-magnetic It is suitable for image formation with a one-component developer.

  However, there are difficulties in producing a positively charged chemical toner. That is, in order to stably disperse the dispersant and the resin particles in the aqueous medium, it is necessary to use a polar monomer such as acrylic acid or methacrylic acid that promotes negative chargeability.

  In the prior art, in order to impart a positive charge to the toner, a compound that imparts positive chargeability such as an ammonium group is internally added to the toner as a positive charge control agent, or an external additive such as positively charged silica is added. For this reason, toner has been imparted with positive chargeability. However, these methods have problems in cost and stability (see, for example, Patent Document 1).

  Further, examples of the photoreceptor used for image formation using the positively chargeable toner include an amorphous silicon photoreceptor excellent in durability and an organic photoreceptor (OPC) having a stable latent image forming ability. However, in the positively charged image forming method, it is required to control the photosensitive layer provided in the vicinity of the surface of the photoconductor so that it is not worn out. Therefore, it is absolutely necessary to completely remove foreign matter adhering to the photoconductor surface. It was difficult to perform such cleaning. Therefore, it has been impossible to solve the problem of image flow caused by foreign matter adhering to the surface of the photoreceptor. In order to solve these problems, measures have been taken to incorporate abrasive fine particles of 300 to 1000 nm in the toner. However, the abrasive fine particles impair the fixability and reduce the gloss and transparency of the color image. (For example, refer to Patent Document 2).

Thus, positively charged image forming technology is insufficient for stable image formation, and development of positively charged toner that can produce high-quality toner images that accurately reproduce digital images is still underway. Was in the stage.
JP 2003-302787 A JP 2001166666 A Fundamentals and applications of electrophotography technology (see Electrophotographic Society edited by 1996.11.15 Corona, p. 238-241)

  The present invention has been made in view of the above problems. That is, the present invention provides a positively charged toner that can perform a comfortable image output without the influence of ozone gas during image formation, and can obtain uniform chargeability during charging, a positively charged developer using the positively charged toner, and an image forming method Is intended to provide.

  Another object of the present invention is to provide a positively charged toner having a fast charge rising speed during image formation and no image fluctuation due to a humidity difference, a positively charged developer using the positively charged toner, and an image forming method. It is.

  Furthermore, the present invention provides a positively charged toner, a positively charged developer using a positively charged toner, and an image forming method that do not generate image flow even if abrasive particles are not added to the electrophotographic photoreceptor. It is for the purpose.

  The present invention is achieved by taking the following configurations.

(Claim 1)
A positively charged toner comprising a resin, a release agent, and colored particles, wherein the concentration of a cationic surfactant on the surface of the toner particles is higher than that of a toner particle central portion.

(Claim 2)
The positively charged toner according to claim 1, wherein the concentration of the anionic surfactant in the central part of the toner particle is higher than that of the toner particle surface.

(Claim 3)
The positively charged toner according to claim 1, wherein the concentration of the negatively charged charge control agent in the central part of the toner particles is higher than that of the toner particle surface.

(Claim 4)
The positively charged toner according to claim 1, wherein an average value of the circularity of the toner particles is 0.954 to 0.986.

(Claim 5)
The positively charged toner according to claim 1, wherein the cationic surfactant is a quaternary ammonium salt having a linear or branched alkyl group having 13 to 25 carbon atoms. .

(Claim 6)
A positively charged developer comprising the positively charged toner according to claim 1 and a silicone resin-coated carrier.

(Claim 7)
6. A non-magnetic one-component image forming method, wherein an image is formed using the positively charged toner according to claim 1.

(Claim 8)
An image forming method comprising developing a digitally exposed amorphous silicon photoreceptor using the positively charged toner according to claim 1.

(Claim 9)
An image forming method comprising developing a positively charged organic photoconductor subjected to digital exposure using the positively charged toner according to claim 1.

  According to the present invention, by using the positively charged toner, a comfortable working environment free from the influence of ozone gas at the time of image formation is ensured, and it is possible to provide a printer and a copying machine for a narrow office or general household.

  Further, according to the present invention, a uniform charging performance can be obtained at the time of charging, a charging rising speed is high at the time of image formation, and a stable image can be obtained by a positively charged toner capable of maintaining a stable charging property for a long period of time. It has become possible to develop the formation over a long period of time. That is, it is possible to stably maintain image uniformity due to line width variation and mode difference during mass printing.

  Furthermore, in the present invention, it is possible to smoothly remove the residual toner and deposits on the photosensitive member without adding abrasive particles that impair the fixing property and the transparency of the image. Image formation is now possible.

  In general, when a positively charged toner is manufactured, a positively chargeable charge control agent is internally added to the toner, or positively chargeable silica or the like is externally added to ensure positively chargeability.

  The positively charged toner refers to a polar toner that can be reversely developed with respect to the positively charged photoreceptor. Here, the reversal development is a development method in which a toner charged with the same polarity as that of the latent image is attached to a region exposed to light of a photoreceptor to visualize the toner.

  In the present invention, a positively chargeable toner can be produced by using a toner having a higher concentration of cationic surfactant on the toner particle surface than in the toner particle inside (center portion). That is, a negatively charged toner particle is formed and then a cationic surfactant is present on the toner particle surface. By forming toner particles by such a method, it has become possible to stably hold a positive charge on the surface of the toner particles.

  Further, in the present invention, the addition of negatively chargeable silica as an external additive to such toner particles does not affect the positive chargeability of the toner, but rather the charge on the toner particle surface and the external additive. Since the electrostatic attractive force acts, the external additive is hardly separated from the toner particles. As a result, the amount of deposits on the surface of the photoreceptor due to the external additive is reduced, and image defects due to deposits are less likely to occur.

  Furthermore, in the toner of the present invention, it is estimated that a small amount of the cationic surfactant on the surface of the toner particles is transferred to the photoreceptor, but high temperature and high humidity (for example, without adding abrasive fine particles in the toner (for example, It has been found that a stable toner image can be obtained without causing image flow under an environment of 30 ° C. and 80% RH.

  In the present invention, the concentration of the cationic surfactant on the toner particle surface is made higher than that at the center of the toner particle by treating the surface of the toner particle with a cationic surfactant during the toner particle production process. .

  Examples of the cationic surfactant used in the present invention include compounds having the following structures.

(In the formula, R represents a substituted or branched alkyl group having 13 to 25 carbon atoms.)
Among these, stearyl trimethyl ammonium chloride and lauryl trimethyl ammonium chloride are preferable.

  For example, there are the following two methods for detecting the presence of a large amount of cationic surfactant on the toner particle surface.

(1) Method of measuring by separately dissolving the toner particle surface and the central cationic surfactant The toner particle surface is washed with ion-exchanged water or methanol, and the amount of the cationic surfactant on the surface is determined. . Next, the toner particles are dissolved in methyl ethyl ketone, the cationic surfactant contained in the toner particle central portion is extracted with a hydroalcoholic mixed solvent, and the amount thereof is quantified.

(2) Method for determining the amount of cationic surfactant by analyzing the cross-section of toner particles Generated from the cationic surfactant with an analytical instrument such as a “time-of-flight secondary ion mass spectrometer” (TOF-SIMS) The molecular fragment ions are analyzed to determine the presence distribution of the cationic surfactant on the toner particle surface and inside.

  In the toner embedding and scraping method, toner particles are sufficiently dispersed in a room temperature curable epoxy resin, and then cured at an ambient temperature of 40 ° C. for 2 days to obtain a cured product in which the toner particles are embedded. Using an ultramicrotome equipped with a diamond knife, the surface is smoothed and then the surface is smoothed.

  Next, the treatment of the toner particle surface with a cationic surfactant will be described.

  The positively charged toner of the present invention is obtained by treating the toner particle surface with a cationic surfactant.

  The cationic surfactant to be treated is preferably an aqueous solution having a cationic surfactant having a concentration of 0.1 to 10% by mass as an active ingredient (pure surfactant), and an aqueous solution of 0.5 to 3% by mass. More preferred.

  In the present invention, if necessary, a cationic surfactant and a nonionic surfactant may be used in combination.

  The treatment method of treating the surface of the toner particles with a cationic surfactant is to mix the above cationic surfactant aqueous solution into a solution in which the toner particles are dispersed, stir-treat, dehydrate, A method of washing with 40 times washing water is preferred. It has been confirmed that the charge amount of the positively charged toner obtained by this method is stabilized.

  The positively chargeable toner of the present invention can form a good image when used as a two-component developer in combination with a non-magnetic one-component developer or a carrier whose surface of magnetic particles is coated with a silicone resin. It has been confirmed.

  In the case of a two-component developer, when combined with a carrier coated with a silicone resin on the surface of magnetic particles, it is confirmed that the amount of charge does not fluctuate even in an environment where charging is fast and stirring is performed for a long time. Has been.

  In addition, when used as a non-magnetic one-component developer, it has been confirmed that the surface of the developing roller covered with a silicone resin forms a better image. The resin coated on the surface of the developing roller is preferably a combination of silicone resin and fluororesin.

  The toner according to the present invention is preferably used as a non-magnetic one-component developer as described above. However, the toner according to the present invention has a process in which a large load is applied to the toner during image formation. It has sufficient strength that it can be used for image formation of a one-component system. As described above, the reason why the toner according to the present invention is produced through the resin particle agglomeration process and can obtain such strength is not clear, but is probably due to the following reason. Is done.

  That is, since the resin particles are aggregated while fusing at the molecular level when the toner particles are produced, it is presumed that the individual particles are firmly aggregated to express such a high strength.

  Further, since the toner particles have a rounded shape with an average circularity of 0.954 to 0.986, as will be described later, even if stress is applied to the toner particles, this stress is released appropriately. It is also presumed that the toner particles are not destroyed.

  Next, the average value of the circularity of the toner particles will be described.

  The average value of the circularity of the toner particles used in the present invention is 0.954 to 0.986.

  By setting the average value of the circularity of the toner particles within the above range, it is possible to improve image uniformity due to line width variation and mode difference during mass printing.

  The average value of circularity is a value obtained from the following formula when 2000 or more toner particles having a particle diameter of 1 μm or more are measured.

Circularity = (perimeter of equivalent circle) / (perimeter of toner particle projection image)
= 2π × (particle projected area / π) ^1/2 / (periphery length of toner particle projected image)
Here, the equivalent circle is a circle having the same area as the toner particle projection image, and the equivalent circle diameter is the diameter of the equivalent circle.

  In addition, as a measuring method of the said circularity, it can measure by "FPIA-2000" (made by Sysmec). At this time, the average value of the equivalent circle diameter is defined by the following equation.

Average value of equivalent circle diameter = 2 × (projected area of particle / π) ^1/2
The method for producing a positively charged toner according to the present invention is produced through a step of treating the surface of toner particles with a cationic surfactant.

  The toner particles are preferably formed by a production method in which a polymerizable monomer is polymerized in an aqueous medium, but the monomer is contained in a liquid (in an aqueous medium) to which an emulsion of necessary additives is added. After preparing fine resin particles by a method such as an emulsification association method and adding charge controllable resin particles as necessary, agglomerating agents such as organic solvents and salts are added to agglomerate and melt the resin particles. It is manufactured by the method of wearing.

<Emulsion association method>
Further, as another method for producing the toner particles according to the present invention, an emulsion association method is preferable. That is, a method of agglomerating resin particles or resin solution droplets in an aqueous medium to form a single toner particle is preferable. Among them, a method of salting out and fusing is preferable. Examples of this method include the methods described in JP-A Nos. 5-265252, 6-329947, and 9-15904. That is, a method of salting out, agglomerating, and fusing a plurality of fine particles composed of resin particles and colorants, or a constituent material such as resin particles and a colorant, particularly in water using an emulsifier Then, a coagulant with a critical coagulation concentration or higher is added for salting out, and at the same time, the formed polymer is heated and fused at a temperature higher than the glass transition temperature of the polymer itself to gradually grow the particle size while forming fused particles. When the desired particle size is reached, a large amount of water is added to stop particle size growth, and the shape is controlled by smoothing the particle surface while heating and stirring, and the particles are heated in a fluidized state while containing water. By drying, the positively charged toner of the present invention can be formed. Here, a solvent that is infinitely soluble in water, such as alcohol, may be added simultaneously with the flocculant.

  In the method for producing toner particles according to the present invention, the composite resin fine particles and the colorant particles formed through the step of polymerizing the polymerizable monomer after the release agent is dissolved in the polymerizable monomer are salted out. / The method of fusing is preferably used. When the wax component is dissolved in the polymerizable monomer, the wax component may be dissolved and dissolved, or may be melted and dissolved.

  In addition, as a method for producing the positively charged toner of the present invention, a step of salting out / fusing composite resin fine particles and colorant particles obtained by a multistage polymerization method is preferably used.

  Here, the multistage polymerization method is a method in which the polymerization reaction is performed in multiple stages when producing composite resin particles, and the resulting resin particles form a molecular weight gradient from the center of the particles toward the surface layer. This is intended to be performed. For example, a method of forming a low molecular weight surface layer by first obtaining a high molecular weight resin particle dispersion and then newly adding a polymerizable monomer and a chain transfer agent is employed. According to this multi-stage polymerization method, the molecular weight distribution of the resin particles can be expanded in order to obtain toner particles in which offset generation is prevented. That is, phases having different molecular weight distributions are formed in one resin particle.

  Next, each step of producing toner particles by a multistage polymerization method and treating the toner particles with a cationic surfactant to produce a positively charged toner will be described.

1: Production process of resin particles (to be a raw material of toner particles) (multistage polymerization method)
2: A salting out / fusion process in which resin particles and colorant particles are salted out / fused to form a toner particle dispersion 3: toner particles are solid-liquid separated from the toner particle dispersion and separated from the toner particles Solid-liquid separation / washing process in which a toner cake is prepared by washing to remove unnecessary dispersants, etc. 4: After re-dispersing the washed toner cake in an aqueous medium, a cationic surfactant is added. Cationic surfactant treatment step to be treated 5: Step of washing excess cationic surfactant from toner particles with water and drying 6: Step of adding and mixing an external additive to the dried toner particles Each step will be described in detail.

1: Production process of resin particles (multistage polymerization method)
In the present invention, it is preferable to employ a multi-stage polymerization method of three-stage polymerization or more from the viewpoint of production stability and crushing strength of the resulting toner. Hereinafter, the two-stage polymerization method and the three-stage polymerization method, which are representative examples of the multistage polymerization method, will be described. The toner obtained by such a multistage polymerization reaction preferably has a low molecular weight surface layer from the viewpoint of crushing strength.

<Two-stage polymerization method>
The two-stage polymerization method is a method for producing composite resin particles composed of a central part (core) formed from a release agent and a resin and a surface (shell) formed from a molecular weight resin different from the central part. .

  This method will be described in detail. First, a release agent is dissolved in a monomer to prepare a monomer solution, and the monomer solution is dispersed in oil droplets in an aqueous medium. A dispersion of resin particles containing a release agent is prepared by polymerization treatment (first stage polymerization).

  Next, a polymerization initiator and a monomer for obtaining a molecular weight resin different from the first stage polymerization are added to the dispersion of the resin particles, and the monomer is polymerized in the presence of the resin particles (second In this method, a coating layer made of a resin (monomer polymer) having a molecular weight different from that of the central portion is formed on the surface of the resin particles by performing step polymerization.

<Three-stage polymerization method>
The three-stage polymerization method is a method for producing composite resin particles composed of a central part (core) formed from a resin, an intermediate layer containing a release agent, and a surface (shell) formed from a low molecular weight resin. is there. The positively charged toner of the present invention exists as the composite resin particles as described above.

  This method will be specifically described. First, a dispersion of resin particles obtained by a polymerization process (first-stage polymerization) according to a conventional method is added to an aqueous medium, and a mold release is performed in the aqueous medium. After the monomer solution in which the agent is dissolved in the monomer is dispersed in oil droplets, this system is polymerized (second-stage polymerization) to form a release agent on the surface of the resin particles (core particles). A coating layer (intermediate layer) made of a resin containing a monomer (monomer polymer) is formed to prepare a dispersion of composite resin particles (for example, high molecular weight resin-intermediate molecular weight resin).

  Next, a polymerization initiator and a monomer for obtaining a low molecular weight resin are added to the obtained dispersion of composite resin particles, and the monomer is polymerized in the presence of the composite resin particles (third-stage polymerization). ), A coating layer made of a low molecular weight resin (monomer polymer) is formed on the surface of the composite resin particles. In the above method, it is preferable to incorporate the intermediate layer so that the release agent can be finely and uniformly dispersed.

  The aqueous medium used in the present invention refers to an aqueous solution of a surfactant that may contain an organic solvent. Examples of the organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, tetrahydrofuran, and the like, and an alcohol-based organic solvent that does not dissolve the resulting resin is preferable.

  Moreover, it is preferable that the glass transition temperature (Tg) of a composite resin particle exists in the range of 44-64 degreeC, More preferably, it is 46-54 degreeC.

  The softening point of the composite resin particles is preferably in the range of 95 to 140 ° C.

  The positively charged toner of the present invention is obtained by fusing resin particles on the surface of the resin and colored particles by a salting-out / fusing method to form a resin layer. This will be described below. .

2: Salting / fusion process In this salting-out / fusion process, the composite resin particles and the colorant particles obtained by the multi-stage polymerization process are salted out / fused (salting out and fusion occur simultaneously). This is a step of obtaining irregular (non-spherical) toner particles.

  In the present invention, salting out / fusion means that salting out (aggregation of particles) and fusion (disappearance of the interface between particles) occur simultaneously or salting out and fusion occur simultaneously. . In order to perform salting-out and fusion at the same time, it is preferable to agglomerate particles (composite resin particles, colorant particles) under a temperature condition higher than the glass transition temperature (Tg) of the resin constituting the composite resin particles. . In the present invention, it is preferable to perform the salting-out / fusion process in the presence of an anionic surfactant.

  In this salting-out / fusion process, internal additive particles such as charge control agents (fine particles having a number average primary particle size of about 10 to 1000 nm) may be salted out / fused together with the composite resin particles and the colorant particles. Good.

  By controlling the temperature and time of the salting-out / fusion process, the average value of the circularity of the toner particles can be in a specific range.

3: Solid-liquid separation / washing process In this solid-liquid separation / washing process, the solid-liquid separation process for solid-liquid separation of the toner particles from the dispersion system of toner particles obtained in the above process, and the solid-liquid separated toner A cleaned toner cake is obtained by a cleaning step of removing deposits such as an anionic surfactant and a salting-out agent from the particles (toner cake). Here, the solid-liquid separation method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a solid-liquid separation method using a filter press or the like.

4: Cationic surfactant treatment step To the toner cake obtained by solid-liquid separation and washing, water is added to prepare a toner particle dispersion having a concentration that can be easily treated with the cationic surfactant. Specifically, the solid content concentration is preferably 5 to 40% by mass. A solution in which the cationic surfactant according to the present invention is dissolved is added to the toner particle dispersion, and the mixture is stirred for 10 minutes to 8 hours to adsorb or react the cationic surfactant on the surface of the toner particles.

  After the treatment is completed, the cationic surfactant-treated dispersion is subjected to solid-liquid separation and washing, and then removed from the excess cationic surfactant to obtain a cationic surfactant-treated toner cake.

5: Drying step This step is a step for drying the cationic surfactant-treated toner cake.

  Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like.

  The water content of the dried toner particles is preferably 5% by mass or less, and more preferably 2% by mass or less.

  In addition, when the toner particles that have been dried are aggregated due to weak interparticle attraction, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

  Next, each constituent factor used in the toner particle manufacturing process will be described in detail.

<Polymerizable monomer>
As a polymerizable monomer for producing the resin particles used in the present invention, a hydrophobic monomer is an essential constituent, and a crosslinkable monomer is used as necessary. Further, it is preferable to use a hydrophobic monomer that can form a copolymer of acrylic acid or methacrylic acid.

(1) Hydrophobic monomer The hydrophobic monomer is not particularly limited, and a conventionally known monomer can be used. In addition, one or more of acrylic acid or methacrylic acid can be used in combination so as to satisfy the required characteristics.

  Specifically, (meth) acrylic acid ester monomers, monovinyl aromatic monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, diolefin monomers , Halogenated olefin monomers and the like can be used.

  Examples of (meth) acrylic acid ester monomers include acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, Examples include ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. It is done.

  Examples of vinyl aromatic monomers include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples thereof include styrene monomers such as 4-dimethylstyrene and 3,4-dichlorostyrene and derivatives thereof.

  Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, vinyl benzoate, and examples of vinyl ether monomers include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether, and the like. It is done.

  Examples of monoolefin monomers include ethylene, propylene, isobutylene, 1-butene, 1-pentene, 4-methyl-1-pentene, and examples of diolefin monomers include butadiene, isoprene, Examples include chloroprene.

(2) Crosslinkable monomer A crosslinkable monomer may be added to improve the properties of the resin particles. Examples of the crosslinkable monomer include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.

(3) Monomer having an acidic polar group Examples of the monomer having an acidic polar group include (a) a polymerizable monomer having a carboxyl group (—COOH), and (b) a sulfone group (—SO ₃ ). Mention may be made of polymerizable monomers having H).

  Examples of the polymerizable monomer having a carboxyl group (a) include acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, maleic acid monooctyl ester, And metal salts such as Na and Zn.

  Examples of the polymerizable monomer having a sulfone group (b) include sulfonated styrene and its Na salt, allylsulfosuccinic acid, octyl allylsulfosuccinate, and Na salts thereof.

  In the present invention, the polymerizable monomer having a carboxyl group (a) is preferably used, and methacrylic acid and acrylic acid are particularly preferably used.

<Anionic surfactant>
In order to perform miniemulsion polymerization using the above-mentioned polymerizable monomer, it is preferable to disperse oil droplets in an aqueous medium using an anionic surfactant. The surfactant that can be used in this case is not particularly limited, and the following anionic surfactants can be mentioned as examples of suitable compounds.

  Examples of the anionic surfactant include sulfonate (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfone diphenylurea-4,4-diazo-bis-amino-8-naphthol. -6-sulfonate sodium, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sulfonate sodium, etc. ), Sulfate esters (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, stear) Potassium phosphate, calcium oleate and the like).

  In the present invention, the anionic surfactants represented by the following general formulas (1) and (2) are particularly preferably used.

General formula (1)
R ¹ (OR ² ) _n OSO ₃ M
General formula (2)
R ¹ (OR ² ) _n SO ₃ M
In the general formulas (1) and (2), R ¹ represents an alkyl group or arylalkyl group having 6 to 22 carbon atoms, preferably an alkyl group or arylalkyl group having 8 to 20 carbon atoms, more preferably It is a C9-16 alkyl group or arylalkyl group.

Examples of the alkyl group having 6 to 22 carbon atoms represented by R ¹ include n-hexyl group, n-heptyl group, n-octyl group, n-decyl group, n-undecyl group, n-hexadecyl group, cyclo propyl group, a cyclopentyl group, a cyclohexyl group, and examples of the arylalkyl group represented by R ^1, benzyl, diphenylmethyl group, cinnamyl group, a styryl group, a trityl group and a phenethyl group.

In the general formulas (1) and (2), R ² represents an alkylene group having 2 to 6 carbon atoms, preferably an alkylene group having 2 to 3 carbon atoms. Examples of the alkylene group having 2 to 6 carbon atoms represented by R ² include an ethylene group, a trimethylene group, a tetramethylene group, a propylene group, and an ethylethylene group.

  In general formula (1), (2), n is an integer of 1-11, Preferably it is 2-10, More preferably, it is 2-5, Most preferably, it is 2-3.

  In the general formulas (1) and (2), examples of the monovalent metal element represented by M include sodium, potassium, and lithium. Of these, sodium is preferably used.

  Specific examples of the surfactant represented by the general formulas (1) and (2) are shown below, but the present invention is not limited thereto.

Compound _{(101): C 10 H 21} (OCH 2 CH 2) 2 OSO 3 Na
Compound _{(102): C 10 H 21} (OCH 2 CH 2) 3 OSO 3 Na
Compound _{(103): C 10 H 21} (OCH 2 CH 2) 2 SO 3 Na
Compound _{(104): C 10 H 21} (OCH 2 CH 2) 3 SO 3 Na
Compound (105): C ₈ H ₁₇ (OCH ₂ CH (CH ₃ )) ₂ OSO ₃ Na
Compound (106): C ₁₈ H ₃₇ (OCH ₂ CH ₂ ) ₂ OSO ₃ Na
<Colorant>
The positively charged toner of the present invention is obtained by salting out / fusion-bonding the composite resin particles and the colorant particles. Examples of the colorant constituting the positively charged toner of the present invention (colorant particles used for salting out / fusion with composite resin particles) include various inorganic pigments and organic pigments. A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.

  Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

  These inorganic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

  When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, it is preferable to add 20 to 60% by mass in the toner from the viewpoint of imparting predetermined magnetic properties.

  A conventionally well-known thing can be used as an organic pigment, A preferable organic pigment is illustrated below.

  Examples of the magenta or red pigment include C.I. I. Pigment red 30, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 184, C.I. I. And CI Pigment Red 185.

  Examples of the pigment for orange or yellow include C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. And CI Pigment Yellow 156.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  These organic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably it is 3-15 mass%.

<Release agent>
A well-known thing can be used as a mold release agent used by this invention.

  In this way, the resin particles containing the release agent in the resin particles are salted out / fused in the aqueous medium with the colorant particles, whereby a toner in which the release agent is finely dispersed can be obtained.

  In the toner of the present invention, low molecular weight polypropylene (number average molecular weight = 1500 to 9000), low molecular weight polyethylene and the like are preferable as the substance having a releasing function, and ester compounds represented by the following formula are particularly preferable.

R _1- (OCO-R ₂ ) _n
In the formula, n is an integer of 1 to 4, preferably 2 to 4, more preferably 3 to 4, and particularly preferably 4. R ₁ and R ₂ each represents a hydrocarbon group that may have a substituent. R ₁ has 1 to 40 carbon atoms, preferably 1 to 20 carbon atoms, and more preferably 2 to 5 carbon atoms. R ₂ has 1 to 40 carbon atoms, preferably 16 to 30 carbon atoms, and more preferably 18 to 26 carbon atoms.

  Next, the example of a typical compound is shown below.

  In the present invention, crystalline polyester can also be used as a release agent. As the crystalline polyester, a polyester obtained by reacting an aliphatic diol and an aliphatic dicarboxylic acid (including an acid anhydride and an acid chloride) is preferable.

  The amount of the compound added is 1 to 30% by mass, preferably 2 to 20% by mass, and more preferably 3 to 15% by mass with respect to the whole toner.

6: External additive treatment process The cationic surfactant-treated toner particles obtained above may be used as a toner as it is, but the positive chargeability on the toner particles is stabilized, fluidity is improved and cleaning is performed. For the purpose of improving the properties, so-called external additives can be added to the toner particles and used. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used.

  As the inorganic fine particles that can be used as the external additive, negatively chargeable external additives can be preferably used. From the viewpoints of preventing release from the toner particles, stabilizing the chargeability, and preventing contamination of the photoreceptor and the transfer member, negatively chargeable silica is preferable.

  Specifically, silica fine particles, titanium fine particles, alumina fine particles and the like can be preferably used. These inorganic fine particles are preferably hydrophobic.

  Specific examples of the silica fine particles include commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., and commercially available products TS-720 manufactured by Cabot Corporation. TS-530, TS-610, H-5, MS-5 and the like.

  Specific examples of the titanium fine particles include, for example, commercial products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., and commercial products MT-100S, MT-100B, MT-500BS, MT-600, and MT manufactured by Teika Co., Ltd. -600SS, JA-1, commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd., commercial products IT-S, IT-OA manufactured by Idemitsu Kosan Co., Ltd. , IT-OB, IT-OC and the like.

  Specific examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd., and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

  Examples of the organic fine particles that can be used as the external additive include spherical fine particles having a number average primary particle diameter of about 10 to 2000 nm. Examples of the constituent material of the organic fine particles include polystyrene, polymethyl methacrylate, styrene-methyl methacrylate copolymer and the like.

  Examples of the lubricant that can be used as an external additive include metal salts of higher fatty acids. Specific examples of the metal salts of such higher fatty acids include zinc stearate, aluminum stearate, copper stearate, magnesium stearate, calcium stearate, and the like; zinc oleate, manganese oleate, iron oleate, olein Oleic acid metal salts such as acid copper and magnesium oleate; palmitate metal salts such as zinc palmitate, copper palmitate, magnesium palmitate and calcium palmitate; linoleic acid metal salts such as zinc linoleate and calcium linoleate; ricinol Examples include ricinoleic acid metal salts such as zinc acid and calcium ricinoleate.

  The addition amount of the external additive is preferably about 0.1 to 5% by mass with respect to the toner.

  Examples of the apparatus for mixing the external additive with the toner include various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer. Among these, a Henschel mixer is preferable.

  In the present invention, the external additive is added, but it is not necessary to add an external additive for the purpose of imparting abrasive particles.

  Next, the positively charged developer according to the present invention will be described.

  The positively charged toner of the present invention can also be used as a non-magnetic one-component developer and a two-component developer used by mixing with a carrier.

  Hereinafter, a positively charged two-component developer using a mixture of positively charged toner and carrier will be described.

  As the carrier, a carrier in which magnetic particles are coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin is preferably used. The resin for coating is not particularly limited, and known resins can be used. Specifically, olefin resins, styrene resins, styrene-acrylic resins, silicone resins, ester resins, or fluorine-containing resins can be used. Polymeric resins and the like are used, and among these, silicone resins are preferable.

  As the magnetic particles, known particles made of metals such as iron, ferrite and magnetite, alloys of these metals with metals such as aluminum and lead, and the like can be used, and among these, ferrite particles are preferable.

  The volume average particle size of the carrier is preferably 15 to 100 μm, more preferably 25 to 80 μm. The volume average particle diameter of the carrier can be measured by a laser diffraction particle size distribution measuring apparatus “Heros” (manufactured by Sympathic Co., Ltd.) equipped with a wet disperser.

  As the photoconductor according to the present invention, a positively charged organic photoconductor (OPC) or an amorphous silicon photoconductor is preferably used. When used in combination with the positively charged toner of the present invention and the positively charged developer according to the present invention, the photoconductor is long. An image stable for a period can be obtained.

  The positively charged organic photoreceptor generally has a multi-layer structure in which an undercoat layer (UCL) is provided on a conductive support, and a charge transport layer (CTL) and a charge generation layer (CGL) that are functionally separated thereon are provided in that order. preferable. However, a positively charged photoreceptor having a single layer structure may have a configuration in which a photosensitive layer (charge generation + charge transport) is provided on an undercoat layer (UCL) on a conductive support.

  An amorphous silicon photoconductor is a photoconductor having an amorphous silicon (sometimes referred to as a-Si) layer or an amorphous silicon layer, and disclosed in JP-A-54-83746 and JP-A-57-11556. Known amorphous silicon photoconductors can be used in JP-A-60-67951, JP-A-62-168161, JP-A-57-158650, and the like.

  The image forming method according to the present invention is preferably a method of forming an image by a positive charging method using the positively charged toner of the present invention in an image forming apparatus equipped with an amorphous silicon photosensitive member or a positively charged organic photosensitive member.

  As an example of the image forming system according to the present invention, an intermediate transfer belt type tandem color image forming apparatus will be described.

  FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention.

  The image forming apparatus shown in FIG. 1 can be used as a copying machine, a laser beam printer, or the like. The image forming apparatus shown in FIG. 1 includes units 10Y, 10M, 10C, and 10Bk, a belt-shaped intermediate transfer member 16, transfer rollers 17Y, 17M, 17C, and 17Bk, a recording paper transport roller 18, and a fixing device 2. It has. In the present invention, the belt-shaped intermediate transfer member 16 includes the belt-shaped intermediate transfer member according to the present invention as a belt material. In the present invention, a polyimide resin is used as a belt material for the intermediate transfer member 16 and an endless belt of the fixing device 2 described later. The polyimide resin used for the belt material used in the image forming apparatus according to the present invention will be described later.

  The units 10Y, 10M, 10C, and 10Bk can be rotated at predetermined peripheral speeds (process speeds) in the clockwise direction indicated by arrows, respectively, on the photosensitive drums 11Y, 11M, 11C, and 11Bk (not shown, but the photosensitive drums have flanges). It is fixed.) Around the photosensitive drums 11Y, 11M, 11C, and 11Bk, corotron chargers 12Y, 12M, 12C, and 12Bk, exposure units 13Y, 13M, 13C, and 13Bk, and color developing units (yellow developing unit 14Y and magenta developing unit) 14M, cyan developing device 14C, black developing device 14Bk) and photoreceptor cleaners 15Y, 15M, 15C, and 15Bk.

  Four units 10Y, 10M, 10C, and 10Bk are arranged in parallel to the intermediate transfer belt 16, but an appropriate order is set according to the image forming method, such as the order of the units 10Bk, 10Y, 10C, and 10M. can do.

  The intermediate transfer belt 16 can be rotated by the backup roller 30 and the support rollers 31, 32, 33 in the counterclockwise direction indicated by the arrow at the same peripheral speed as the photosensitive drums 11 </ b> Y, 11 </ b> M, 11 </ b> C, 11 </ b> Bk. , 33 is disposed so that a part thereof is in contact with the photosensitive drums 11Y, 11M, 11C, and 11Bk. The intermediate transfer belt 16 is provided with a belt cleaning device 34. The support roller 31 plays the role of a tension roller and is arranged to be movable in the direction of the surface of the intermediate transfer belt 16 so that the tension of the intermediate transfer belt 16 can be adjusted.

  The transfer rollers 17Y, 17M, 17C, and 17Bk are disposed inside the intermediate transfer belt 16 and at positions facing the portions where the intermediate transfer belt 16 and the photosensitive drums 11Y, 11M, 11C, and 11Bk are in contact with each other. The photosensitive drums 11Y, 11M, 11C, and 11Bk and a primary transfer portion (nip portion) for transferring the toner image to the intermediate transfer belt 16 are formed.

  The bias roller 35 is disposed on the surface side of the intermediate transfer belt 16 on which the toner image is carried so as to face the backup roller 30 with the intermediate transfer belt 16 interposed therebetween. The bias roller 35 and the backup roller 30 via the intermediate transfer belt 16 form a secondary transfer portion (nip portion). Further, the backup roller 30 includes an electrode roller 26 that rotates while being pressed against the backup roller 30.

  The fixing device 2 is disposed so that the recording sheet P can be conveyed after passing through the secondary transfer portion.

  In the image forming apparatus shown in FIG. 1, in the unit 10Y, the photosensitive drum 11Y is rotationally driven. In conjunction with this, the corotron charger 12Y is driven to uniformly charge the surface of the photosensitive drum 11Y to a predetermined polarity and potential. The photosensitive drum 11Y having a uniformly charged surface is then exposed imagewise by the exposure device 13Y, and an electrostatic latent image is formed on the surface.

  Subsequently, when the electrostatic latent image is developed by the yellow developing device 14Y, a toner image is formed on the surface of the photosensitive drum 11Y.

  When the toner image passes through the primary transfer portion (nip portion) between the photosensitive drum 11Y and the intermediate transfer belt 16, an intermediate transfer belt 16 is generated by an electric field formed by a transfer bias applied from the transfer roller 17Y. The primary transfer is sequentially performed on the outer peripheral surface.

  Thereafter, the toner remaining on the photoreceptor drum 11Y is cleaned and removed by the photoreceptor cleaner 15Y. Then, the photosensitive drum 11Y is subjected to the next transfer cycle.

  The above transfer cycle is similarly performed in the units 10M, 10C, and 10Bk, and a second color toner image, a third color toner image, and a fourth color toner image are sequentially formed and superimposed on the intermediate transfer belt 16. As a result, a full-color toner image is formed.

  The full-color toner image transferred to the intermediate transfer belt 16 reaches the secondary transfer portion (nip portion) where the bias roller 35 is installed by the rotation of the transfer belt 16.

  The recording sheet P is fed at a predetermined timing between the intermediate transfer belt 16 and the bias roller 35 in the secondary transfer portion. The toner image carried on the intermediate transfer belt 16 is transferred onto the recording sheet P by the pressure conveyance by the bias roller 35 and the backup roller 30 and the rotation of the intermediate transfer belt 16.

  The recording sheet P to which the toner image has been transferred is conveyed to the fixing device 2 and the toner image is fixed by pressure / heating treatment. After the transfer, the intermediate transfer belt 16 is prepared for the next transfer by removing residual toner by a belt cleaning device 34 provided downstream of the secondary transfer portion.

  Polyimide resin is preferably used as a belt material for the intermediate transfer belt of the image forming apparatus and the endless belt of the fixing apparatus according to the present invention.

  In the image forming apparatus shown in FIG. 1, a positively charged organic photoreceptor or amorphous silicon photoreceptor can be used as the photoreceptor, and a magnetic two-component developer type or a non-magnetic one-component type can be used as the developing device.

  FIG. 2 is a cross-sectional configuration diagram illustrating an example of a developing device used for a non-magnetic one-component developer.

  In FIG. 2, 11 is a photosensitive drum, 102 is a developing roller, 103 is a metal elastic blade, 104 is a non-magnetic one-component toner, 105 is a stirring blade, 106 is a recovery plate, and 107 is a silicone resin. The developing roller 102 has a surface coated with a silicone resin 107.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

Example 1
<Preparation of Toner 1-C>
1. 1. Production of toner particles (1) 1-1. Production of resin particles as raw material for toner particles (polymerizable monomer solution 1-1-1)
In a flask equipped with a stirrer, 96.0 g of a mold release agent (Exemplary Compound (19)) was added to a mixture of the following polymerizable monomers, heated to 80 ° C. and dissolved. This is designated as “polymerizable monomer solution 1-1-1.”

Styrene 172.9g
n-Butyl acrylate 55.0g
Methacrylic acid 23.1g
On the other hand, a surfactant solution was prepared by dissolving 2.5 g of anionic surfactant (101) in 1340 g of ion-exchanged water in a 5000 ml separable flask equipped with a stirrer, a temperature sensor, and a cooling tube. After heating the surfactant solution to 80 ° C., the “polymerizable monomer solution 1-1-1-” was obtained by a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. 1 "was mixed and dispersed for 2 hours to prepare an emulsified liquid (dispersed liquid) containing emulsified particles (oil droplets) having a dispersed particle diameter (482 nm).

  Next, after adding 1460 ml of ion-exchanged water, an initiator solution in which 7.5 g of a polymerization initiator (potassium persulfate: KPS) was dissolved in 142 ml of ion-exchanged water and 6.74 g of n-octanethiol were added, This system was heated and stirred at 80 ° C. for 3 hours to perform polymerization (first stage polymerization) to obtain resin particles (a dispersion of high molecular weight resin particles). This is referred to as “resin particles (1-1-1)”.

  To this was added an initiator solution in which 11.6 g of a polymerization initiator (KPS) was dissolved in 220 ml of ion-exchanged water, and then the following “polymerizable monomer solution 1-1” was performed at a temperature of 80 ° C. -2 "was added dropwise over 1 hour.

(Polymerizable monomer solution 1-1-2)
291.2 g of styrene
n-Butyl acrylate 132.2g
Methacrylic acid 42.9g
n-Octanethiol 7.51g
After completion of the dropwise addition, polymerization (second stage polymerization) was performed by heating and stirring for 2 hours, followed by cooling to 28 ° C. and using “resin particles (1-1-1)” as raw materials. -1-2) "was obtained.

1-2. Aggregation Step of Toner Particles (1) “Colorant Particle C” and “Resin Particles” were prepared using a dispersion of “Colorant Particle Dispersion C” and “Resin Particles (1-1-2)” shown below. (1-1-2) ".

(Preparation of colorant particle dispersion C)
59.0 g of the anionic surfactant (101) was dissolved in 1600 ml of ion-exchanged water with stirring, and the cyan pigment C.I. I. Pigment Blue 15: 1 280.0 g was gradually added, followed by dispersion treatment using “CLEARMIX” (manufactured by M Technique Co., Ltd.) to prepare “Colorant Particle Dispersion Liquid C”. The particle diameter of the colored particles in this dispersion was 93 nm.

<Aggregation process>
“Resin particles (1-1-2)” 259.3 g (in terms of solid content), 1120 g of ion-exchanged water, and 237 g of the above “colorant particle dispersion C” were mixed with a temperature sensor, a cooling tube, and a nitrogen introduction device. Then, the mixture was stirred in a four-necked flask equipped with a stirring device. After adjusting the temperature in the container to 30 ° C., the pH was adjusted to 10 by adding a 5 mol / liter sodium hydroxide aqueous solution.

  Next, an aqueous solution in which 55.3 g of magnesium chloride hexahydrate was dissolved in 55.3 ml of ion-exchanged water was added at 30 ° C. over 10 minutes with stirring. After standing for 3 minutes, the temperature was raised, and the temperature of the system was raised to 90 ° C. over 60 minutes to cause aggregation of “resin particles (1-1-2)” and “colorant particles C”.

  While continuing stirring and heating, the particle size of “toner particles (1)” was measured with “Coulter Counter TA-II” (manufactured by Beckman Coulter), and when the volume average particle size reached 5.5 μm. Then, an aqueous solution in which 15.3 g of sodium chloride was dissolved in 100 ml of ion-exchanged water was added to suppress particle growth to obtain “Dispersion of Toner Particles 1-C”.

2. Solid-liquid separation and washing process After applying “dispersion of toner particles 1-C” to a centrifugal dehydrator, washing is performed while sprinkling 50 times the amount of ion-exchanged water with respect to the solid content to obtain “toner cake 1-C”. Got.

3. Cationic Surfactant Treatment Step 20 parts by weight of “Toner Cake 1-C” is dispersed in 100 parts by weight of a 1% by weight aqueous solution in which the cationic surfactant stearyltrimethylammonium chloride is dissolved, and stirred for 1 hour. A dispersion 1-C of toner particles treated with a cationic surfactant was obtained.

4). Solid-liquid separation and drying process After applying the cationic surfactant-treated toner particle dispersion 1-C again to a centrifugal dehydrator, the solid content is washed while sprinkling 25 times the amount of ion-exchanged water. Thereafter, the toner particles were dried with hot air at 40 ° C. to obtain “Toner Particles 1-C”.

5). External additive mixing step To 100 parts by mass of the above “toner particles 1-C”, 0.8 part by mass of hydrophobic silica “R805” (manufactured by Nippon Aerosil Co., Ltd.) is added, and “Henschel mixer” (Mitsui Miike Chemical Co., Ltd.) is added. The peripheral speed of the rotary blade of (made) was set to 30 m / sec and mixed for 25 minutes. Thereafter, coarse particles were removed using a sieve having an opening of 45 μm to prepare “Toner 1-C” composed of “Toner Particles 1-C”.

<Preparation of Toner 1-M>
Cyan pigment used in the production of “Toner 1-C” I. Pigment Blue 15: 1, 280.0 g was added to magenta pigment C.I. I. “Toner 1-M” was prepared in the same manner except that it was changed to Pigment Red 184, 420 g.

<Preparation of Toner 1-Y>
Cyan pigment used in the production of “Toner 1-C” I. Pigment Blue 15: 1, 280.0 g was added to yellow pigment C.I. I. “Toner 1-Y” was prepared in the same manner except that it was changed to Pigment Yellow 74, 420 g.

<Preparation of Toner 1-Bk>
Cyan pigment used in the production of “Toner 1-C” I. “Toner 1-Bk” was prepared in the same manner except that Pigment Blue 15: 1, 280.0 g was changed to 420 g of neutral carbon black “Regal 660” (manufactured by Cabot).

  When the above toner was washed with methanol to extract the surfactant on the surface of the toner particles, a cationic surfactant was detected. Next, in order to extract the surfactant inside the toner particles, the toner was dissolved in methyl ethyl ketone, and the solution was extracted with ion-exchanged water. As a result, an anionic surfactant was detected.

Example 2
<Preparation of Toner 2-C>
Except that the 1.0 mass% aqueous solution of stearyltrimethylammonium chloride used in the cationic surfactant treatment step of “Toner 1-C” was changed to a 2.0 mass% aqueous solution of lauryltrimethylammonium chloride. Similarly, “Toner 2-C” was produced.

<Preparation of Toner 2-M>
Cyan pigment used in the production of “Toner 2-C” I. Pigment Blue 15: 1, 280.0 g was added to magenta pigment C.I. I. “Toner 2-M” was prepared in the same manner except that it was changed to Pigment Red 184, 420 g.

<Preparation of Toner 2-Y>
Cyan pigment used in the production of “Toner 2-C” I. Pigment Blue 15: 1, 280.0 g was added to yellow pigment C.I. I. “Toner 2-Y” was prepared in the same manner except that it was changed to Pigment Yellow 74, 420 g.

<Preparation of Toner 2-Bk>
Cyan pigment used in the production of “Toner 2-C” I. “Toner 2-Bk” was prepared in the same manner except that Pigment Blue 15: 1, 280.0 g was changed to 420 g of neutral carbon black “Regal 660” (manufactured by Cabot).

  When the above toner was washed with methanol to extract the surfactant on the surface of the toner particles, a cationic surfactant was detected. Next, in order to extract the surfactant inside the toner particles, the toner was dissolved in methyl ethyl ketone, and the solution was extracted with ion-exchanged water. As a result, an anionic surfactant was detected.

Example 3
<Preparation of Toner 3-C>
Except for changing the 1.0 mass% aqueous solution of stearyltrimethylammonium chloride used in the cationic surfactant treatment step of “Toner 1-C” to a 1.0 mass% aqueous solution of stearyldimethylamine hydrochloride. Produced “Toner 3-C” in the same manner. <Production of Toner 3-M>
Cyan pigment used in the production of “Toner 3-C” I. Pigment Blue 15: 1, 280.0 g was added to magenta pigment C.I. I. “Toner 3-M” was prepared in the same manner except that it was changed to Pigment Red 184, 420 g.

<Preparation of Toner 3-Y>
Cyan pigment C.I used in the production of “Toner 3-C”. I. Pigment Blue 15: 1, 280.0 g was added to yellow pigment C.I. I. “Toner 3-Y” was prepared in the same manner except that it was changed to Pigment Yellow 74, 420 g.

<Preparation of Toner 3-Bk>
Cyan pigment C.I used in the production of “Toner 3-C”. I. “Toner 3-Bk” was produced in the same manner except that Pigment Blue 15: 1, 280.0 g was changed to 420 g of neutral carbon black “Regal 660” (manufactured by Cabot).

  When the above toner was washed with methanol to extract the surfactant on the surface of the toner particles, a cationic surfactant was detected. Next, in order to extract the surfactant inside the toner particles, the toner was dissolved in methyl ethyl ketone, and the solution was extracted with ion-exchanged water. As a result, an anionic surfactant was detected.

Comparative Example 1
<Preparation of Toner 4-C>
In the production of “Toner 1-C”, “Toner 4-C” was prepared in the same manner except that the cationic surfactant treatment step (step of dispersing and stirring stearyltrimethylammonium chloride in a 1% by mass aqueous solution) was omitted. Was made.

<Preparation of Toner 4-M>
Cyan pigment used in the production of “Toner 4-C” I. Pigment Blue 15: 1 280.0 g was added to magenta pigment C.I. I. “Toner 4-M” was prepared in the same manner except that it was changed to Pigment Red 184, 420 g.

<Preparation of Toner 4-Y>
Cyan pigment used in the production of “Toner 4-C” I. Pigment Blue 15: 1 280.0 g was added to yellow pigment C.I. I. “Toner 4-Y” was prepared in the same manner except that the pigment yellow was changed to 74, 420 g.

<Preparation of Toner 4-Bk>
Cyan pigment used in the production of “Toner 4-C” I. “Toner 4-Bk” was prepared in the same manner except that 280.0 g of Pigment Blue 15: 1 was changed to 420 g of neutral carbon black “Regal 660” (manufactured by Cabot).

  The surfactant on the toner particle surface was extracted by washing the above toner with methanol, but no cationic surfactant was detected.

Comparative Example 2
<Preparation of Toner 5-C>
In the aggregation process of “Toner 1-C”, 259.3 g of “internal resin particles (2-1-2)” (in terms of solid content), 1120 g of ion-exchanged water, and 23.7 g of “colorant dispersion C” Then, 2.83 g of a dispersion of the following chemical formula (II) (solid content concentration 20% by mass) is added to the cationic surfactant treatment step (in a 1% by mass aqueous solution of stearyltrimethylammonium chloride). “Toner 5-C” was prepared in the same manner except that the step of dispersing and stirring was omitted.

<Preparation of Toner 5-M>
Cyan pigment used in the production of “Toner 5-C” I. Pigment Blue 15: 1, 280.0 g was added to magenta pigment C.I. I. “Toner 5-M” was prepared in the same manner except that it was changed to Pigment Red 184, 420 g.

<Preparation of Toner 5-Y>
Cyan pigment used in the production of “Toner 5-C” I. Pigment Blue 15: 1, 280.0 g was added to yellow pigment C.I. I. “Toner 5-Y” was prepared in the same manner except that it was changed to Pigment Yellow 74, 420 g.

<Preparation of Toner 5-Bk>
Cyan pigment used in the production of “Toner 5-C” I. “Toner 5-Bk” was prepared in the same manner except that Pigment Blue 15: 1, 280.0 g was changed to 420 g of neutral carbon black “Regal 330” (Cabot).

  The surfactant on the toner particle surface was extracted by washing the above toner with methanol, but no cationic surfactant was detected. Next, in order to extract the surfactant inside the toner particles, the toner was dissolved in methyl ethyl ketone, and the solution was extracted with ion-exchanged water. Both the cationic surfactant and the anionic surfactant were detected. .

  Table 1 shows the presence or absence of the cationic surfactant treatment, the compound and amount thereof, and the average value of the circularity of the toner particles.

<< Preparation of two-component developer >>
100 parts by mass of ferrite particles having a volume average particle size of 40 μm were immersed in a coating resin solution obtained by dissolving 1 part by mass of a condensation reaction type silicone resin in 50 parts by mass of xylene. Thereafter, xylene was removed by heating and stirring, and further heat treatment was performed at 200 ° C. for 3 hours to sinter, and then aggregates were sieved to prepare a carrier having a silicone resin coating layer.

  Each toner prepared above and the above carrier were mixed with a “V-type mixer” so that the toner concentration was 6% by mass to prepare each two-component developer.

<Evaluation>
Evaluation was performed using two kinds of evaluation machines.

<Evaluation machine 1>
Image formation by changing the photoconductor of the commercially available electrophotographic printer "EPSON 9500" (manufactured by Epson) to a positively charged organic photoconductor and the developing device to a non-magnetic one-component system using a developing roller coated with silicone resin The process was used by changing it so that an image can be formed with positive charging.

<Evaluation machine 2>
The photoconductor of a commercially available electrophotographic printer “Sitios 9331” (manufactured by Konica Minolta) was modified to an amorphous silicon photoconductor, and the image forming process was changed so as to form an image with positive charging.

  The evaluation was carried out for the following items by loading each toner and each developer prepared above in an evaluation machine and performing printing.

<Image stability-line width->
A line chart having a width of 100 μm was printed in four colors of C, M, Y, and Bk, and the line width was measured every 10,000 prints, and a total of 100,000 prints were printed continuously day and night.

Evaluation criteria ◎: Line width of each color is in the range of 100 ± 5 μm ○: Line width of each color is in the range of 100 ± 10 μm ×: Sample that does not fall in the range of 100 ± 10 μm even for any one color was there.

<Image stability-mode difference->
After 5000 full-color character / photograph mixed images were printed, the print cycle of printing 5000 black character images was repeated 5 times, and each color solid image (solid) was printed at the time of image switching, and the uniformity was visually evaluated.

Evaluation Criteria A: Excellent with only uniform images with no gloss unevenness and density unevenness ○: Gloss unevenness and density unevenness are detected in a very small part of the image, but good with no problem ×: Whitish portions such as density unevenness and missing transfer Occurrence or poor image quality.

<Image flow by photoconductor filming>
The surface of the photoreceptor after continuous printing of 300,000 sheets or 1 million sheets was visually observed, and the image flow due to filming (dirt adhesion on the photoreceptor) was visually evaluated.

  Image flow is an image failure that is printed as a continuous image for one day and then printed on the entire surface of the next morning with an 8-point character image and the outline of the character is blurred or toner is diffused around the character. It is.

Evaluation machine 1 (positively charged organic photoconductor—non-magnetic one-component developer) Evaluation standard ◎: Filming at the time of printing 300,000 sheets, no image blurring ○: Although slight filming is recognized at the time of printing 300,000 sheets No image flow occurred x: Filming occurred on the surface of the photoconductor with less than 300,000 prints, and image flow occurred frequently.

Evaluation machine 2 (amorphous silicon photoreceptor-2 component developer) Evaluation standard A: Filming at the time of printing 1 million sheets, no image flow occurred ○: Image flow was observed although slight filming was observed at the time of printing 1 million sheets No occurrence x: Filming occurs on the surface of the photosensitive member when printing is less than 1 million sheets, and image flow frequently occurs.

  Table 2 shows the evaluation results evaluated by the evaluator 1.

  Table 3 shows the evaluation results evaluated by the evaluator 2.

  From Table 2 and Table 3, it can be seen that Example “Toner 1-C to Toner 3-Bk” of the present invention is superior to Comparative Example “Toner 4-C to Toner 5-Bk” in all evaluation items. .

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present invention. It is a cross-sectional block diagram which shows an example of the developing device used for a nonmagnetic one-component developer.

Explanation of symbols

10Y, 10M, 10C, 10Bk Unit 11Y, 11M, 11C, 11Bk Photosensitive drum 12Y, 12M, 12C, 12Bk Corotron charger 13Y, 13M, 13C, 13Bk 15C, 15Bk Photoconductor cleaner 16 Intermediate transfer belt (intermediate transfer member)
17Y, 17M, 17C, 17Bk Transfer roller 30 Backup roller 31, 32, 33 Support roller 34 Belt cleaning device 35 Bias roller 36 Electrode roller P Recording sheet

Claims (9)

A positively charged toner comprising a resin, a release agent, and colored particles, wherein the concentration of a cationic surfactant on the surface of the toner particles is higher than that of a toner particle central portion. The positively charged toner according to claim 1, wherein the concentration of the anionic surfactant in the central part of the toner particle is higher than that of the toner particle surface. The positively charged toner according to claim 1, wherein the concentration of the negatively charged charge control agent in the central part of the toner particles is higher than that of the toner particle surface. The positively charged toner according to claim 1, wherein an average value of the circularity of the toner particles is 0.954 to 0.986. The positively charged toner according to claim 1, wherein the cationic surfactant is a quaternary ammonium salt having a linear or branched alkyl group having 13 to 25 carbon atoms. . A positively charged developer comprising the positively charged toner according to claim 1 and a silicone resin-coated carrier. 6. A non-magnetic one-component image forming method, wherein an image is formed using the positively charged toner according to claim 1. An image forming method comprising developing a digitally exposed amorphous silicon photoreceptor using the positively charged toner according to claim 1. An image forming method comprising developing a positively charged organic photoconductor subjected to digital exposure using the positively charged toner according to claim 1.

Images