JP2008281655A - Toner and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate filming and blocking caused by a release agent exposed on a toner surface, and to provide a toner which avoids hot offset and excels in cleaning property and a method for manufacturing the same. <P>SOLUTION: Toner particles 1a before elution treatment include at least a binder resin 2, a colorant (not shown) and a paraffinic wax 3a and an ester or carnauba wax 3b as a release agent, wherein the paraffinic wax 3a and the ester or carnauba wax 3b are dispersed in the binder resin 2 in a uniform dispersion diameter. When such toner particles 1a before elution treatment are subjected to elution treatment, the paraffinic wax 3a in the release agent exposed on the surfaces of the toner particles 1a is eluted into a solvent and removed and a toner 1b after elution treatment is obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a toner and a manufacturing method thereof.

  Along with the recent trend toward higher speed and energy saving, a low-temperature fixing toner having high sharp melt property is required as a toner used in an image forming apparatus. Since such toner has a high affinity with the fixing roller and tends to be offset to the fixing roller at the time of fixing, the toner is easily separated from the fixing roller by adding a release agent to the toner. In order to satisfy the releasability from the fixing roller, the amount of the release agent added to the toner tends to increase. However, as the amount of release agent added increases, in the toner manufacturing process using the kneading and pulverization method, there is a high probability that the release agent in the toner becomes the pulverization interface, and the distribution and dispersion state of the release agent is controlled to an optimum state. In addition, the wax commonly used as a release agent is exposed at a high concentration on the toner surface, and the powder flowability and thermal aggregation of the toner are deteriorated. Problems such as blocking, filming and fusion occur.

  In order to overcome the disadvantages of these release agent-containing toners, the release agent is encapsulated in the toner to reduce the proportion of low molecular weight components such as the release agent exposed on the toner surface, thereby blocking and filming. However, it is difficult to control the encapsulation process, and it is difficult to obtain a desired coating state.

  Also, in order to ensure low-temperature fixability of the toner having no release agent on the surface, it is necessary to lower the melting point of the release agent. In this case, a problem of high-temperature offset occurs, and a good fixing region (non-fixed area) The offset area) cannot be secured.

  In the first conventional technique, in the toner manufacturing method by suspension polymerization containing 10 to 40 parts by weight of the release agent with respect to 100 parts by weight of the polymerizable monomer, a surface modifying liquid is added after the polymerization process is completed. By removing the release agent on the toner surface, it is possible to obtain a toner whose durability is greatly improved mainly under high temperature and high humidity. The surface modifying liquid is a combination of a surfactant, an organic acid, an organic acid salt, an aliphatic amine derivative, a water-soluble organic solvent, potassium hydroxide, phosphoric acid, and pure water (see Patent Document 1).

  In the second conventional technique, by using at least one of a supercritical fluid and a subcritical fluid (preferably carbon dioxide having a low critical temperature), the release agent on the toner surface is removed, A toner that is excellent in releasability, blocking resistance, and the like and that has high durability under high temperature and high humidity can be obtained (see Patent Document 2).

JP-A-7-128908 JP 2005-266621 A

  In the first conventional technique, for a polymerized toner containing a large amount of low-melting wax as a release agent and having a wax abundance ratio of 5% by weight or more in the toner outermost surface layer, the release agent in the toner surface component Although the abundance ratio can be made less than 5% by weight and durability at high temperature and high humidity can be improved, the effect of improving the cleaning property by forming a recess on the toner surface accompanying the removal of the wax cannot be obtained. Also, since there is almost no release agent on the outermost surface layer of the toner, the melting point of the release agent must be lowered in order to ensure low temperature fixability, but there is a risk of high temperature offset, and a good fixing area over a wide range. (Non-offset area) cannot be secured.

  In the second conventional technique, a large-scale manufacturing apparatus is required for processing with a supercritical fluid or a subcritical fluid under heat and pressure, leading to an increase in cost. Further, since the release agent may be removed not only to the toner surface but also to the inside thereof, the toner fixing performance cannot be ensured.

  An object of the present invention is to solve the above-mentioned conventional problems by removing at least one of two or more types of release agents exposed on the toner surface, so that high temperature offset does not occur and cleaning is performed. An object of the present invention is to provide a toner having excellent properties and a method for producing the same.

The present invention is a toner including at least a binder resin, a colorant, and two or more release agents having different solubility in a solvent having a solubility parameter of 7.5 or less,
Of the release agents present in a region having a depth of 700 nm or less from the toner surface, the release agent having higher solubility in the solvent is removed by elution into the solvent. Toner.

In the present invention, the difference between the solubility parameter of the release agent having a higher solubility in the solvent and the solubility parameter of the solvent is 0.5 or less,
The difference between the solubility parameter of the release agent having the lower solubility in the solvent and the solubility parameter of the solvent is 1 or more.

  In addition, the present invention is characterized in that the solvent is one or more selected from n-hexane and n-heptane.

In the invention, it is preferable that an average circularity of the toner is 0.955 or more.
In the invention, it is preferable that the binder resin includes a polyester and a polyester-vinyl hybrid resin.

  The present invention is further characterized in that it includes a copolymer of an α-olefin-maleic anhydride copolymer and a maleic anhydride monoester as a dispersion aid for the release agent.

  In the invention, it is preferable that the mold release agent contains at least one selected from ester waxes and carnauba waxes, and paraffin wax.

  In the invention, it is preferable that the paraffin wax is present in an amount of 3 parts by weight or more in a region where the depth from the toner surface exceeds 700 nm.

  In the present invention, the melting point of the paraffin wax is 70 ° C. or less.

  In the present invention, the ester wax and the carnauba wax have a melting point of 80 ° C. or higher.

The present invention also provides a toner manufacturing method for manufacturing the toner,
At least a pre-mixing step of mixing two or more release agents having different solubility in a solvent having a binder resin, a colorant, and a solubility parameter of 7.5 or less;
A melt-kneading step of melt-kneading the mixture obtained by premixing,
A pulverization / classification step of pulverizing and classifying the melt-kneaded product obtained by melt-kneading;
A spheronization step of spheronizing the pulverized product obtained by pulverization and classification;
An elution step of treating the toner particles obtained by spheroidization in the solvent to elute the release agent having higher solubility in the solvent among the release agents contained in the toner particles;
A method for producing a toner, comprising:

  The present invention is characterized in that, in the elution step, the release agent having higher solubility in the solvent among the release agents contained in the toner particles is eluted by irradiating ultrasonic waves. .

  According to the present invention, in the elution step, 1 to 10 parts by weight of the toner particles are added to 100 parts by weight of the solvent, and the solubility of the release agent contained in the toner particles is high in the solvent. It is characterized by eluting the mold release agent.

  According to the present invention, the toner has at least a solubility in a binder resin, a colorant, and a solvent having a solubility parameter (hereinafter referred to as “SP value”, SP: Solubility Parameter) of 7.5 or less (hereinafter simply referred to as “solubility”). Among the release agents existing in a region having a depth of 700 nm or less from the toner surface (hereinafter sometimes referred to as “toner surface layer”), the solubility in a solvent is included. The higher release agent is removed by eluting into the solvent.

  When the release agent having higher solubility in the solvent among the release agents exposed on the surface of the toner before the release agent is eluted (hereinafter referred to as “toner particles”) is eluted from the surface of the toner particles. Since the release agent having a higher solubility in the solvent existing in a region having a depth of 700 nm or less (hereinafter sometimes referred to as “toner particle surface layer”) is removed, moderate irregularities are formed on the toner surface. Even a toner having a small particle size and high circularity does not cause cleaning failure. Further, since the external additive adhering to the carrier surface in the developing device can be scraped off by the concave and convex depressions, it is possible to prevent the charge imparting ability of the carrier from being reduced with respect to the toner.

  When the release agent having higher solubility in the solvent is eluted in the solvent, the content of the release agent in the toner is reduced. However, the release agent having lower solubility in the solvent is not present on the toner surface and the toner surface layer. In a region where the residual from the toner surface exceeds 700 nm (hereinafter sometimes referred to as “inner toner”), the release agent having a higher solubility in the solvent has a lower solubility in the solvent. Since the mold release agent remains without being removed, filming occurs to form a thin film of the mold release agent on the surface of the photosensitive member or intermediate transfer body while ensuring the release property to the heating roller for fixing to the recording medium. Can be suppressed. In addition, it is possible to prevent fusion of toner to the toner regulating blade, fusion of the photosensitive member to the cleaning blade, blocking of the toners, and the like, and the occurrence of high temperature offset can be suppressed. In the two-component development, the toner component is prevented from adhering to the carrier surface.

  According to the present invention, the difference between the SP value of the release agent having higher solubility in the solvent and the SP value of the solvent is 0.5 or less, and the SP value of the release agent having lower solubility in the solvent. And the SP value of the solvent is 1 or more. The SP value is an index indicating the polarity of a substance. The SP value is the square root of the cohesive energy density of the molecules, and represents the magnitude of the cohesive force between the molecules, and is an index of the affinity between the solvent and the release agent. That is, the closer the SP value of the solvent and the release agent, the higher the affinity. When the SP values of the solvent and the release agent are close and the difference is 0.5 or less, the solubility of the release agent in the solvent is increased. Therefore, among the two or more release agents present in the toner particle surface layer, The release agent having an SP value close to the SP value of the solvent is removed by elution in the solvent. On the contrary, when the SP values of the solvent and the release agent are separated and the difference is 1 or more, the solubility of the release agent in the solvent is low, so that the two or more types of release agents present in the toner particle surface layer portion. Among these, the release agent having an SP value far from the SP value of the solvent remains without being eluted in the solvent. Blocking due to the release agent exposed on the surface of the toner while maintaining the fixability of the toner after the elution treatment by combining the release agent having a high solubility in the solvent and the low release agent. The occurrence of filming, fusion, etc. can be prevented.

  For example, if two or more types of release agents exposed on the surface of the toner particles are all eluted, the release agent does not exist on the toner surface layer, so that the toner fixing property cannot be maintained. On the contrary, if all of the two or more types of release agents exposed on the toner particle surface remain, blocking, filming, fusing, etc. due to the release agent exposed on the toner surface may occur. End up.

  According to the invention, the solvent for eluting the release agent is one or more selected from n-hexane and n-heptane. By using n-hexane (SP value 7.3) and n-heptane (SP value 7.4), which are low polarity solvents having an SP value of 7.5 or less, a release agent having a small polarity can be eluted. In addition, the release agent on the surface layer of the toner particles can be efficiently removed.

  According to the invention, the average circularity of the toner is 0.955 or more. As a result, the shape of the toner surface becomes uniform, and the transfer efficiency of moving the toner developed on the photoreceptor onto the medium by electrostatic force is improved. If it is less than 0.955, the toner surface has non-uniform shape, so that the chargeability of the toner is deteriorated and the development accuracy is deteriorated.

  According to the invention, the binder resin includes polyester and a polyester-vinyl hybrid resin. By including the hybrid resin in the binder resin, the compatibility between the polyester and the release agent is improved through this, and the uniform dispersibility of the release agent in the binder resin is improved. Originally, the compatibility between the polyester and the release agent is poor, so it is difficult to uniformly disperse the release agent in the polyester. On the other hand, by using a hybrid resin containing a vinyl copolymer unit having a relatively high compatibility with a release agent and a polyester unit having a high compatibility with polyester as a binder resin for toner, The dispersibility of the release agent can be improved, and the release agent can be prevented from being exposed on the toner surface. In addition, a binder resin containing polyester and a hybrid resin has higher gloss, better color reproducibility, and excellent low-temperature fixability than when a hybrid resin is used alone. In addition, the binder resin containing polyester and hybrid resin is excellent in high temperature offset resistance and pulverization during production.

  In addition, according to the present invention, a copolymer of an α-olefin-maleic anhydride copolymer and a maleic anhydride monoester is further included as a dispersion aid for the release agent. As a toner raw material, it contains a dispersion aid to disperse the release agent in the binder resin, so the compatibility between the binder resin and the release agent is improved, and the amorphous resin particles are refined by the high-pressure homogenizer method. Thus, the release agent is finely dispersed in the binder resin of the resin-containing particles obtained.

  According to the invention, the release agent contains at least one selected from ester wax and carnauba wax and paraffin wax. The ester wax and the carnauba wax have good compatibility with the binder resin and have an SP value of 8.5 to 12, so that they are not easily eluted in a solvent having an SP value of 7.5 or less. On the other hand, paraffin wax is poorly compatible with the binder resin and further has an SP value of 6 to 8, so it elutes in a solvent having an SP value of 7.5 or less and does not remain on the toner surface layer. Since the paraffin wax does not remain on the toner surface layer, the occurrence of blocking, filming, fusing, and the like due to the release agent exposed on the toner surface is reduced. Further, since the ester wax or carnauba wax dispersed in the entire toner has a high melting point, the wax does not bleed out even at a high temperature. As a result, high temperature offset including micro offset can be prevented.

  According to the invention, the paraffin wax is present in an amount of 3 parts by weight or more in a region where the depth from the toner surface exceeds 700 nm. Even if the paraffinic wax on the toner surface layer is eluted with a solvent having an SP value of 7.5 or less, if 3 parts by weight or more of the paraffinic wax having a low melting point is present, the low-temperature fixability is improved and the low-temperature offset is prevented. be able to.

  According to the present invention, since the melting point of the paraffin wax is 70 ° C. or lower, the low-temperature fixability is good, the low-temperature offset can be prevented, and the non-low-temperature offset region can be expanded.

  According to the present invention, since the melting point of the ester wax and the carnauba wax is 80 ° C. or higher, the wax does not bleed even at a high temperature. As a result, high temperature offset including micro offset can be prevented, and the non-high temperature offset region can be expanded.

  According to the present invention, the toner having the above-described effect can be obtained by a production method including a premixing step, a melt-kneading step, a pulverizing / classifying step, a spheronizing step, and an elution step. In the premixing step, at least a binder resin, a colorant, and two or more release agents having different solubility in a solvent having a solubility parameter of 7.5 or less are mixed. In the melt kneading step, the mixture obtained in the premixing step is melt kneaded. In the pulverization / classification step, the solidified product of the melt-kneaded product obtained in the melt-kneading step is pulverized and classified to obtain a pulverized product. In the spheronization step, the pulverized product obtained in the pulverization / classification step is spheroidized to obtain toner particles. In the elution step, the toner particles obtained in the spheronization step are treated in a solvent, and among the release agents contained in the toner particles, the release agent having higher solubility in the solvent is eluted and removed, and the toner is removed. obtain.

  In the toner manufactured by the pulverization method, the release agent tends to become a pulverization interface during pulverization, and the release agent is easily exposed on the surface. Therefore, the effect of the release agent is easily obtained, but filming on the surface of the photoreceptor, fusion to the cleaning blade, reduction in storage stability of the toner, and contamination of the release agent on the carrier surface are likely to occur. By eluting the toner produced by the pulverization method, the release agent on the toner surface layer, which is the cause of such a problem, can be removed, and the above problems can be prevented while maintaining good releasability.

  According to the invention, the release agent contained in the toner particles is eluted by irradiating with ultrasonic waves in the elution step. The elution treatment with the solvent is performed on the toner particles not added externally. Since the toner particles not added externally have poor fluidity and are aggregated, they are difficult to disperse in the solvent. Therefore, by applying ultrasonic vibration, the aggregates of the toner particles are crushed and the dispersion is promoted, so that the release agent can be uniformly eluted in the solvent. Further, since the eluted release agent is diffused and released from the toner particles, the release agent does not remain on the toner surface layer.

  According to the invention, in the elution step, 1 to 10 parts by weight of toner particles are added to 100 parts by weight of the solvent to elute the release agent contained in the toner particles. The amount of the solvent must be sufficient to disperse the toner particles. If the toner particles are added in an amount of 1 to 10 parts by weight in 100 parts by weight of the solvent, they can be sufficiently dispersed by a stirrer or the like. It is. If the added amount of toner particles exceeds 10 parts by weight, a dispersion failure is likely to occur and the release agent cannot be removed efficiently. Conversely, if the amount of toner particles added is less than 1 part by weight, the toner particles are sufficiently dispersed, but the solvent becomes excessive and the efficiency is lowered, which is not preferable.

  The toner of the present invention includes at least a binder resin, a colorant, and two or more release agents having different solubility in a solvent having an SP value of 7.5 or less, and a depth from the toner surface of 700 nm or less ( The release agent having higher solubility in the solvent among the release agents present in the toner surface layer (hereinafter also referred to as “toner surface layer”) is removed by elution into the solvent.

  Of the release agents exposed on the surface of the toner particles, the release agent with the higher solubility in the solvent elutes in the solvent and is removed, so that moderate irregularities are formed on the toner surface, and the small particle size is circular. Even a high degree of toner does not cause poor cleaning. Further, since the external additive adhering to the carrier surface in the developing device can be scraped off by the concave and convex depressions, it is possible to prevent the charge imparting ability of the carrier from being reduced with respect to the toner.

  When the release agent having higher solubility in the solvent is eluted in the solvent, the content of the release agent in the toner is reduced. However, the release agent having lower solubility in the solvent is not present on the toner surface and the toner surface layer. It remains without being eluted, and the release agent having a higher solubility in the solvent and the release agent having a lower solubility in the solvent remain in the toner without being removed. It is possible to suppress the occurrence of filming that forms a thin film of a release agent on the surface of the photosensitive member or the intermediate transfer member while ensuring the releasability with respect to the roller. In addition, it is possible to prevent fusion of toner to the toner regulating blade, fusion of the photosensitive member to the cleaning blade, blocking of the toners, and the like, and the occurrence of high temperature offset can be suppressed. In the two-component development, the toner component is prevented from adhering to the carrier surface.

  FIG. 1 is a cross-sectional view schematically showing an example of the toner of the present invention. FIG. 1A shows the toner particles 1a before the elution process, and FIG. 1B shows the toner 1b of the present invention after the elution process. The toner particles 1a before the elution treatment include at least a binder resin 2, a colorant (not shown), and a paraffinic wax 3a and an ester-based or carnauba-based wax 3b as a releasing agent. Wax 3a and ester or carnauba wax 3b are dispersed with a uniform dispersion diameter. When the toner particles 1a before such elution processing are subjected to elution processing, the paraffin wax 3a out of the release agent exposed on the surface of the toner particles 1a is eluted and removed by the solvent, and the toner 1b after the elution processing is removed. can get.

  The paraffin wax 3a and the ester or carnauba wax 3b form a plurality of domains and are dispersed in the toner particles 1a before the elution treatment. The wax domains of the paraffinic wax 3a and the ester-based or carnauba-based wax 3b (hereinafter referred to as “wax domain”) refer to the matrix of the binder resin 2 in the continuous phase region where the ratio of the binder resin 2 is high. It is an island-like phase having a closed interface with a low ratio and a high ratio of the paraffinic wax 3a and the ester-based or carnauba-based wax 3b. Since the average longest diameter of the wax domain of the paraffinic wax 3a is 700 nm, the depth of the recess formed by elution and removal of the paraffinic wax 3a exposed on the surface of the toner particles 1a before the elution treatment is removed. The maximum depth from the surface of the toner 1b is 700 nm. That is, the paraffin wax 3a is removed from the release agent in the region having a depth of 700 nm or less from the surface of the toner particles 1a of the present invention.

  The solvent for eluting the paraffinic wax 3a contained in the toner particles 1a is preferably at least one selected from n-hexane and n-heptane. By using n-hexane (SP value 7.3) and n-heptane (SP value 7.4), which are low polar solvents having an SP value of 7.5 or less, paraffin wax 3a having a small polarity (SP value 6) -8) can be eluted, and the paraffin wax 3a on the surface layer of the toner particles 1a can be efficiently removed.

  Since the paraffin wax 3a has poor compatibility with the binder resin 2 and has an SP value of 6 to 8, it is eluted in a solvent having an SP value of 7.5 or less and does not remain on the surface of the toner 1b. On the other hand, the ester-based or carnauba-based wax 3b has good compatibility with the binder resin 2 and further has an SP value of 8.5 to 12, so that it is difficult to elute into a solvent having an SP value of 7.5 or less. Since the paraffin wax 3a does not remain on the surface of the toner 1b, the occurrence of blocking, filming, fusion, etc. due to the release agent exposed on the surface of the toner 1b is reduced. Further, since the stealth or carnauba wax 3b dispersed throughout the surface including the surface of the toner 1b has a high melting point, the wax does not bleed out even at a high temperature. As a result, high temperature offset including micro offset can be prevented.

  The binder resin 2 preferably includes a polyester and a polyester-vinyl hybrid resin. By including the hybrid resin in the binder resin, the compatibility between the polyester and the release agent is improved through this, and the uniform dispersibility of the release agent in the binder resin is improved. Originally, the compatibility between the polyester and the release agent is poor, so it is difficult to uniformly disperse the release agent in the polyester. On the other hand, by using a hybrid resin containing a vinyl copolymer unit having a relatively high compatibility with a release agent and a polyester unit having a high compatibility with polyester as a binder resin for toner, The dispersibility of the release agent can be improved, and the release agent can be prevented from being exposed on the toner surface. In addition, a binder resin containing polyester and a hybrid resin has higher gloss, better color reproducibility, and excellent low-temperature fixability than when a hybrid resin is used alone. In addition, the binder resin containing polyester and hybrid resin is excellent in high temperature offset resistance and pulverization during production.

  FIG. 2 is a process diagram showing a procedure of a toner manufacturing method according to an embodiment of the present invention. The toner manufacturing method in the present embodiment includes a pre-mixing step in step s1, a melt-kneading step in step s2, a pulverizing / classifying step in step s3, a spheronizing step in step s4, and an elution step in step s5. including.

<Pre-mixing process>
In the pre-mixing step of step s1, at least a binder resin, a colorant, and two or more release agents having different solubility in a solvent having a solubility parameter of 7.5 or less are mixed. The toner of the present invention contains two or more release agents having different solubility in a binder resin, a colorant, and a solvent having a solubility parameter of 7.5 or less as essential components, and further a dispersion aid for the release agent. And a toner additive such as a charge control agent.

  The binder resin used in the present invention preferably contains a polyester and a polyester-vinyl hybrid resin. The polyester-vinyl hybrid resin is a resin in which a polyester unit and a vinyl copolymer unit are chemically bonded. As the hybrid resin, any of a block copolymer and a graft copolymer can be used. The hybrid resin is produced by a polycondensation reaction and addition in the same reaction vessel in the presence of a polyester monomer, a vinyl monomer, and a bireactive monomer capable of reacting with both the polyester monomer and the vinyl monomer. A method of simultaneously performing the polymerization reaction or a method of independently performing the condensation polymerization reaction and the addition polymerization reaction can be mentioned, but a known method can be used without any particular limitation.

  Specifically, the polyester unit used in the present invention and the polyester unit in the hybrid resin can be synthesized from the following polyhydric alcohol and polyhydric carboxylic acid component. Examples of the polyhydric alcohol component include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, and 1,5-pentanediol. 1,6-hexanediol, neopentylene glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene And dihydric alcohols such as bisphenol A alkylene oxide adducts such as bisphenol A.

  In order to make the polymer non-linear, a trihydric or higher polyhydric alcohol can be used. Examples of the trivalent or higher alcohol component include glycerin, sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, pentaerythritol, 1,2,4-butanetriol, 1,2,5- Examples include pentanetriol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene.

  Examples of the polyvalent carboxylic acid component include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, malonic acid, succinic acid, Examples thereof include dibasic carboxylic acids such as adipic acid, sebacic acid, glutaric acid, alkyl succinic acid (for example, n-octyl succinic acid, n-dodecenyl succinic acid), acid anhydrides and alkyl esters thereof.

  In addition, as a vinyl copolymer unit in the hybrid resin, a conventionally known unit can be used. However, in consideration of grindability and charging characteristics, a styrene monomer, an acrylate monomer or a methacrylic acid ester monomer is formed. Preferably it is a unit. Styrene monomers include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, p-ethyl styrene, 2,4-dimethyl styrene, pn-butyl styrene, p-ter. -Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-dodecyl methylene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,4-dichloro styrene, etc. It is done. Examples of the acrylate monomer or methacrylate monomer include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, Alkyl ester of acrylic acid or methacrylic acid such as stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, stearyl methacrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate 2-hydroxyethyl methacrylate, glycidyl methacrylate, bisglycidyl methacrylate, polyethylene glycol dimethacrylate, etc. methacryloxyethyl phosphate. Of these, particularly preferred are ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate and the like.

  Examples of the both reactive monomers include fumaric acid, maleic acid, citraconic acid, itaconic acid, acrylic acid, and methacrylic acid esters. Of these, fumaric acid, maleic acid, citraconic acid and itaconic acid are also used as polyvalent carboxylic acid components of polyester and hybrid resins. Of these, methacrylic acid esters are also used as methacrylic acid ester monomers for hybrid resins.

  The ratio of polyester to hybrid resin in the binder resin is preferably 3: 1 to 10: 1. By setting the ratio of polyester to hybrid resin in the above range, gloss, color reproducibility and low-temperature fixability of polyester, compatibility with release agent of hybrid resin, high-temperature offset resistance, and grinding Sex can be achieved at the same time.

  As the colorant, organic dyes, organic pigments, inorganic dyes, inorganic pigments and the like commonly used in the electrophotographic field can be used.

  Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, magnetic ferrite, and magnetite.

  Examples of yellow colorants include chrome lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, and benzidine. Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, and the like.

  Examples of the orange colorant include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment orange 31, C.I. I. And CI Pigment Orange 43.

  Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risol red, pyrazolone red, watching red, calcium salt, lake red C, lake red D, and brilliant carmine 6B. Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, 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 178, C.I. I. And CI Pigment Red 222.

  Examples of purple colorants include manganese purple, fast violet B, and methyl violet lake.

  Examples of blue colorants include bitumen, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated products, first sky blue, induslen blue BC, 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. And CI Pigment Blue 60.

  Examples of the green colorant include chrome green, chromium oxide, pigment green B, micalite green lake, final yellow green G, C.I. I. And CI Pigment Green 7.

  Examples of the white colorant include compounds such as zinc white, titanium oxide, antimony white, and zinc sulfide.

  One colorant can be used alone, or two or more different colorants can be used in combination. Moreover, even if it is the same color, 2 or more types can be used together.

  The colorant is preferably used as a masterbatch. The master batch of the colorant can be produced by kneading the polyester resin and the colorant. The use ratio of the polyester resin and the colorant is not particularly limited, but is preferably 30 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the polyester resin. The master batch is used after being granulated to a particle size of, for example, about 2 to 3 mm.

  Although the content of the colorant in the toner base is not particularly limited, it is preferably 2% by weight or more and 8% by weight or less of the total amount of the toner particles. When a master batch is used, the content is not the master batch amount, but the amount of the colorant itself contained in the toner base. Therefore, when using a master batch, it is preferable to adjust the usage amount of the master batch so that the content of the colorant contained in the toner base is within the above range. The content of the colorant may be the same content for each color, or may be a different content for each color. By using the colorant in the above range, it is possible to form a good image having sufficient image density, high transparency and color developability and excellent image quality.

  Wax is used as the release agent, for example, paraffin wax and derivatives thereof, and petroleum wax such as microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, low molecular polypropylene wax and Derivatives thereof, and hydrocarbon synthetic waxes such as polyolefin polymer waxes and derivatives thereof, carnauba waxes and derivatives thereof, rice waxes and derivatives thereof, candelilla waxes and derivatives thereof, plant waxes such as wood wax, beeswax, whales Animal waxes such as waxes, oil-based synthetic waxes such as fatty acid amides and phenol fatty acid esters, long chain carboxylic acids and derivatives thereof, long chain alcohols and derivatives thereof, Recone polymer, such as higher fatty acids.

  In the present invention, two or more release agents having different solubility in a solvent having an SP value of 7.5 or less are used. As the release agent having a lower solubility in a solvent, ester wax, carnauba wax and the like are preferable. These waxes have an SP value of 8.5 to 12, and hardly dissolve in a solvent having an SP value of 7.5 or less. On the other hand, as the mold release agent having higher solubility in the solvent, paraffin wax is preferable. These waxes have an SP value of 6 to 8, and are well eluted in a solvent having an SP value of 7.5 or less. By using two or more release agents having different solubility in the solvent, only the wax having the higher solubility in the solvent is removed from the toner surface layer portion, so that it is exposed on the toner surface while maintaining the fixing property. Generation | occurrence | production of the blocking, filming, melt | fusion, etc. resulting from a mold release agent can be prevented.

  The difference between the SP value of the release agent having a higher solubility in the solvent and the SP value of the solvent is 0.5 or less, and the SP value of the release agent having the lower solubility in the solvent and the SP value of the solvent The difference is preferably 1 or more. When the SP values of the solvent and the release agent are close and the difference is 0.5 or less, the solubility of the release agent in the solvent is increased. Therefore, among the two or more release agents present in the toner particle surface layer, The release agent having an SP value close to the SP value of the solvent is removed by elution in the solvent. On the contrary, when the SP values of the solvent and the release agent are separated and the difference is 1 or more, the solubility of the release agent in the solvent is low, so that the two or more types of release agents present in the toner particle surface layer portion. Among these, the release agent having an SP value far from the SP value of the solvent remains without being eluted in the solvent. Blocking due to the release agent exposed on the surface of the toner while maintaining the fixability of the toner after the elution treatment by combining the release agent having a high solubility in the solvent and the low release agent. The occurrence of filming, fusion, etc. can be prevented.

  For example, if two or more types of release agents exposed on the surface of the toner particles are all eluted, the release agent does not exist on the toner surface layer, so that the toner fixing property cannot be maintained. On the contrary, if all of the two or more types of release agents exposed on the toner particle surface remain, blocking, filming, fusing, etc. due to the release agent exposed on the toner surface may occur. End up.

  In addition, as the melting point of the release agent having higher solubility in the solvent, the peak temperature of the endothermic peak derived from the melting of the release agent is preferably in the range of 60 ° C. to 70 ° C. in differential scanning calorimetry (DSC). . When the melting point of the release agent having a higher solubility in the solvent is within the above range, the release agent oozes out at a low temperature, thereby preventing a low temperature offset and lowering the fixable temperature.

  The melting point of the release agent having a lower solubility in the solvent is preferably such that the peak temperature of the endothermic peak derived from the melting of the release agent is in the range of 80 ° C. to 100 ° C. in differential scanning calorimetry (DSC). . If the melting point of the release agent with lower solubility in the solvent is in the above range, the release agent does not bleed out in the low temperature range, but bleeds out efficiently in the high temperature range, so high temperature offset including micro offset is unlikely to occur even at high temperatures. can do.

  When the melting point of the release agent having a lower solubility in the solvent and the melting point of the release agent having a higher solubility in the solvent are within the above ranges, the non-offset region can be expanded.

  The amount of the release agent having the lower solubility in the solvent is not particularly limited and can be appropriately selected from a wide range, but is preferably contained in a ratio of 2 wt% to 7 wt% of the total amount of toner particles. If the release agent having a lower solubility in the solvent is less than 2% by weight, the release property to the heating roller used as the fixing unit cannot be exhibited, and a high temperature offset occurs in which the toner adheres to the heating roller. There is a fear. If the release agent having a lower solubility in the solvent exceeds 7% by weight, filming that forms a thin film of the release agent having a lower solubility in the solvent on the surface of the photoreceptor may occur. By setting the release agent having the lower solubility in the solvent to 2% by weight or more and 7% by weight or less of the total amount of the toner particles, it is possible to prevent the occurrence of filming and high temperature offset.

  The amount of the release agent having higher solubility in the solvent is not particularly limited and can be appropriately selected from a wide range, but is preferably contained in a proportion of 1% by weight to 5% by weight of the total amount of toner particles. If the release agent having a higher solubility in the solvent is less than 1% by weight, the releasability of the heating roller used as the fixing unit cannot be exhibited, and a high temperature offset that causes toner to adhere to the heating roller occurs. There is a fear. If the release agent having a higher solubility in the solvent exceeds 5% by weight, filming that forms a thin film of the release agent having a higher solubility in the solvent on the photoreceptor surface may occur. By setting the release agent having a higher solubility in the solvent to 1% by weight or more and 5% by weight or less of the total amount of the toner particles, it is possible to prevent filming and occurrence of high temperature offset.

  In addition to the binder resin, the colorant, and the release agent, the toner raw material may contain additives such as a dispersion aid for the release agent and a charge control agent.

  It is preferable that the dispersion aid for the release agent is compatible with both the binder resin and the release agent. Examples of such a dispersion aid include a copolymer having a portion excellent in compatibility with wax and a portion excellent in compatibility with binder resin.

  Examples of the copolymer having a portion having excellent compatibility with the wax and a portion having excellent compatibility with the binder resin include, for example, a polyolefin portion such as polyethylene having excellent compatibility with the wax and the binder resin. A copolymer with a vinyl polymer moiety such as polystyrene and styrene-acrylic resin having excellent compatibility can be used as a dispersion aid for the release agent. Examples of such copolymers include styrene-ethylene-butadiene block copolymers, styrene-methyl methacrylate block copolymers, ethylene-styrene graft copolymers, maleic anhydride-modified polypropylene, styrene-maleic anhydride copolymers. A polymer etc. are mentioned.

  A commercially available product can be used as a dispersion aid for the release agent. Examples of commercially available dispersion aids include Ceramer 1608 (trade name, manufactured by Toyo Petrolite Co., Ltd.), Ceramer 1251 (trade name, manufactured by Toyo Petrolite Co., Ltd.), and the like. Ceramer 1608 and ceramer 1251 are both copolymers of an α-olefin-maleic anhydride copolymer and a maleic anhydride monoester.

  The dispersing aid for the release agent is preferably contained in the toner raw material at a ratio of 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the binder resin. More preferably, it is contained. By including the dispersion aid in such a ratio, it is possible to uniformly disperse the release agent in the binder resin by exhibiting compatibility with both the binder resin and the release agent. . When the proportion of the dispersion aid is less than 1 part by weight with respect to 100 parts by weight of the binder resin, the content of the dispersion aid is relative to the amount of the binder resin and the release agent to be dispersed in the binder resin. Therefore, it is difficult to make the binder resin and the release agent compatible with each other, and the release agent may not be sufficiently dispersed in the binder resin. If the proportion of the dispersion aid exceeds 10 parts by weight with respect to 100 parts by weight of the binder resin, the original properties of the binder resin may be changed.

  Further, the dispersion aid for the release agent is contained in the toner raw material in the above-mentioned preferred ratio, and more preferably in the ratio of 0.1 parts by weight or more and 10 parts by weight or less with respect to 1 part by weight of the release agent. . When the proportion of the dispersion aid is less than 0.1 parts by weight with respect to 1 part by weight of the release agent, the content of the dispersion aid is small compared to the content of the release agent, and aggregation of the release agent is prevented. It may not be possible. When the proportion of the dispersion aid exceeds 10 parts by weight with respect to 1 part by weight of the release agent, the release agent may be excessively dispersed in the binder resin. If the release agent is too dispersed in the binder resin, the dispersed particle size of the release agent becomes too small, and there is a possibility that sufficient offset resistance cannot be exhibited.

  As the charge control agent, a known charge control agent for positive charge control or negative charge control can be used. By adding the charge control agent, the triboelectric charge amount of the toner can be made suitable. Examples of the charge control agent for controlling positive charge include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof, and triphenylmethane. Examples thereof include derivatives, guanidine salts, and amidine salts. Examples of the charge control agent for controlling the negative charge include oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, naphthenic acid metal salts, metal complexes and metal salts of salicylic acid and its derivatives ( Examples of the metal include chromium, zinc, zirconium, etc.), boron compounds, fatty acid soaps, long-chain alkyl carboxylates, and resin acid soaps. One charge control agent can be used alone, or two or more charge control agents can be used in combination. The amount of the charge control agent used is not particularly limited and can be appropriately selected from a wide range, but it is preferably 0.1 wt% or more and 3 wt% or less of the total amount of toner particles.

  In the pre-mixing step of step s1, the binder resin as described above, the colorant, two or more release agents having different solubility in a solvent having a solubility parameter of 7.5 or less, and a release agent used as necessary. The mold dispersion aid and charge control agent are dry-mixed using a mixer.

  Known mixers can be used, such as Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), super mixer (trade name, manufactured by Kawata Co., Ltd.), Mechano Mill (trade name, manufactured by Okada Seiko Co., Ltd.), etc. Henschel type mixing apparatus, ongmill (trade name, manufactured by Hosokawa Micron Corporation), hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo system (trade name, manufactured by Kawasaki Heavy Industries, Ltd.), and the like. When the toner raw materials are sufficiently mixed by the mixer, the process proceeds to the melt-kneading step of step s2.

<Melting and kneading process>
In the melt-kneading process of step s2, the mixture obtained in the pre-mixing process of step s1 is melt-kneaded by heating to a temperature not lower than the softening point of the binder resin and lower than the thermal decomposition temperature. As a result, the binder resin is softened, and a colorant, a release agent, and the like are dispersed in the binder resin. The specific heating temperature at the time of melt kneading is, for example, about 80 ° C. to 200 ° C., preferably about 100 ° C. to 150 ° C.

  For the melt-kneading, a kneader such as a kneader, a twin-screw extruder, a two-roll mill, a three-roll mill, or a lab blast mill can be used. As such a kneader, for example, TEM-100B (trade name, 1-axis or 2-axis extruder, such as PCM-65 / 87 and PCM-30 (all are trade names, manufactured by Ikegai Co., Ltd.), Needex (trade names, manufactured by Mitsui Mining Co., Ltd.) And an open roll type kneader. The melt kneading may be performed using a plurality of kneaders. When the kneading target is sufficiently melt-kneaded, the process proceeds to the pulverization / classification step of step s3.

<Crushing and classification process>
In the pulverization / classification process of step s3, the solidified product of the melt-kneaded product obtained in the melt-kneading process of step s2 is pulverized to obtain a pulverized product. The melt-kneaded material is cooled and solidified, for example. The solidified product of the melt-kneaded product is pulverized into a coarsely pulverized product having a particle size of about 100 μm to 5 mm by a hammer mill or a cutter mill, and then the coarsely pulverized product is used, for example, using a supersonic jet stream. Melt using a jet-type pulverizer that pulverizes the product, or an impact-type pulverizer that introduces and pulverizes coarsely pulverized material into the space formed between the rotor (rotor) and stator (liner) that rotate at high speed. The solidified product of the kneaded product is pulverized to a desired particle size to obtain a pulverized product.

  In addition, after pulverization by a pulverizer, classification is performed in order to remove fine powder from the pulverized product. The removed fine powder is used as a preliminary kneaded material in the above-described step s2.

  The pulverization and classification are performed so that the volume average particle size of the pulverized product is 3 μm or more and 15 μm or less. In particular, in order to obtain a high-quality image, it is preferable that the volume average particle size of the pulverized product is 3 μm or more and 9 μm or less. In order to further improve the image quality, the volume average particle size of the pulverized product is 5 μm or more and 8 μm or less. It is preferable that If the volume average particle size of the pulverized product is less than 3 μm, the particle size of the toner becomes too small, and there is a possibility that high charge and low fluidity may occur. When this high charging and low fluidization occur, it becomes impossible to stably supply the toner to the photoreceptor, and there is a possibility that background fogging and a decrease in image density may occur. When the volume average particle size of the pulverized product exceeds 15 μm, the toner has a large particle size, so that a high-definition image cannot be obtained. Further, as the toner particle size increases, the specific surface area decreases and the charge amount of the toner decreases. When the charge amount of the toner is small, the toner is not stably supplied to the photoconductor, and there is a possibility that in-machine contamination due to toner scattering occurs. When a pulverized product is obtained in the pulverization / classification process, the process proceeds to the spheronization process in step s4.

<Spheronization process>
In the spheronization process in step s4, the pulverized product obtained in the pulverization / classification process in step s3 is spheroidized to obtain toner particles. Examples of the spheronization treatment in the spheronization step include a method of spheroidizing the pulverized product with a mechanical impact force, a method of sphering the pulverized product with hot air, and the like. Either method may be used to obtain the toner of the present invention.

In the spheronization step, the spheronization process is performed so that the average circularity of the toner particles is 0.955 or more. The circularity (ai) of the toner particles is defined by the following formula (1). The circularity (ai) as defined in the formula (1) is measured by using, for example, a flow type particle image analyzer “FPIA-3000” manufactured by Sysmex Corporation. Further, the sum of the respective circularities (ai) measured for m toner particles is obtained, and the arithmetic average value obtained by Expression (2) for dividing the sum by the number of toner particles m is used as the average circularity (a) of the toner particles. It is defined as
Circularity (ai) = (perimeter of a circle having the same projected area as the particle image)
/ (Peripheral length of projected image of particles) (1)

As a spheroidizing apparatus, a known dry surface modification apparatus can be used. For example, a hybridization system (manufactured by Nara Machinery Co., Ltd.), a Cosmo system (manufactured by Kawasaki Heavy Industries, Ltd.), a mechanofusion (stock of Hosokawa Micron) Company), Mechanomyl (Okada Seiko Co., Ltd.) and the like.

  By spheroidizing the pulverized material in this way, the fluidity can be improved compared to a toner having a non-spherical surface and the toner is prevented from having a low charge amount. can do. As a result, the transferability of the toner to the recording medium can be improved, and the amount of toner consumption can be reduced.

<Elution process>
In the elution process of step s5, the toner particles obtained in the spheronization process are put in a solvent, and the release agent contained in the toner particles is eluted in the solvent. The toner of the present invention is obtained by removing the release agent in this way and then drying at room temperature.

  FIG. 3 is a schematic diagram illustrating the elution process. For example, a solvent 5 having a solubility parameter of 7.5 or less and a stirrer 6 such as n-hexane or n-heptane are placed in the container 4. Then, the paraffin wax 3a which is a release agent exposed on the surface of the toner particles 1a is removed. Thereafter, the dispersion liquid is subjected to suction filtration with a filtration suction device 7, and the precipitate 9 remaining on the filtration filter 8 is dried to obtain toner 1 b.

  As the solvent 5 for eluting the release agent, a solvent having a solubility parameter of 7.5 or less is used.

  The solvent is preferably at least one selected from n-hexane and n-heptane. By using n-hexane (SP value 7.3) and n-heptane (SP value 7.4), which are low polar solvents having an SP value of 7.5 or less, paraffin wax having a small polarity can be eluted. In addition, the paraffinic wax on the surface of the toner particles can be efficiently removed. For example, n-hexane or n-heptane may be used alone as a solvent, or a mixed solvent of n-hexane and n-heptane may be used.

  In the elution step, it is preferable to elute the release agent contained in the toner particles by irradiating ultrasonic waves. The elution treatment with the solvent is performed on the toner particles not added externally. Since the toner particles not added externally have poor fluidity and are aggregated, they are difficult to disperse in the solvent. Therefore, by applying ultrasonic vibration, the aggregates of the toner particles are crushed and the dispersion is promoted, so that the release agent can be uniformly eluted in the solvent. Further, since the eluted release agent is diffused and released from the toner particles, the release agent does not remain on the toner surface layer. Ultrasonic irradiation is performed using, for example, an ultrasonic vibrating rod.

  In the elution step, 1 to 10 parts by weight of toner particles are added to 100 parts by weight of the solvent to elute the release agent contained in the toner particles. The amount of the solvent must be sufficient to disperse the toner. If the toner particles are added in an amount of 1 to 10 parts by weight in 100 parts by weight of the solvent, the toner can be sufficiently dispersed by a stirrer or the like. is there.

For example, the solubility of a release agent such as paraffin wax, ester wax or carnauba wax in n-hexane is 20 g / 100 g even at the lowest. Since the general release agent content of toner particles is 10% by weight or less, the release agent contained in 200 g of toner particles can be eluted with 100 g of n-hexane. Substantially the amount of n-hexane needs a sufficient volume to disperse the toner particles, so that the bulk density of general toner particles is 0.3 g / cm ³ and the density of n-hexane is 0.659 g / Since the volume ratio of 10 parts by weight of toner particles to 100 parts by weight of n-hexane is about 1/5 from cm ^3, it can be sufficiently dispersed by a stirrer or the like. If the amount of toner particles exceeds 10 parts by weight, a dispersion failure tends to occur, and the release agent cannot be removed efficiently. On the other hand, if the amount of toner particles is less than 1 part by weight, the toner particles are sufficiently dispersed, but the amount of the solvent is excessive and the efficiency is lowered, which is not preferable.

  The elution time from the introduction of the toner particles into the solvent until the dispersion is filtered is preferably 1 second or more and 30 seconds or less. When the release agent is put into the solvent, it quickly elutes into the solvent. If the elution time is less than 1 second, the release agent is not sufficiently eluted in the solvent, and if it exceeds 30 seconds, the amount of the release agent to be eluted does not change, and the efficiency is lowered.

  By treating the toner particles in the solvent in this way, the release agent having a higher solubility in the solvent present in the toner particle surface layer is removed, so that appropriate irregularities are formed on the toner surface, and small particles are formed. Even toner with a high diameter and circularity does not cause cleaning failure. Further, since the external additive adhering to the carrier surface in the developing device can be scraped off by the concave and convex depressions, it is possible to prevent the charge imparting ability of the carrier from being reduced with respect to the toner.

  When the release agent having higher solubility in the solvent is eluted in the solvent, the content of the release agent in the toner is reduced. However, the release agent having lower solubility in the solvent is not present on the toner surface and the toner surface layer. The heating roller for fixing to the recording medium remains without being eluted, and the release agent having the higher solubility in the solvent and the release agent having the lower solubility in the solvent remain in the toner without being removed. The filming that forms a thin film of the release agent on the surface of the photosensitive member or the intermediate transfer member can be suppressed while the releasability of the film is secured. In addition, it is possible to prevent fusion of toner to the toner regulating blade, fusion of the photosensitive member to the cleaning blade, blocking of the toners, and the like, and the occurrence of high temperature offset can be suppressed. In the two-component development, the toner component is prevented from adhering to the carrier surface.

  A fluidity improver for improving fluidity may be externally added to the toner of the present invention obtained as described above. As the fluidity improver, known ones can be used, for example, silicon oxide, titanium oxide, silicon carbide, aluminum oxide, calcium carbonate, barium titanate, strontium titanate, metal stearate particles, fluorine resin particles, Examples include acrylic resin particles. A fluidity improver can be used individually by 1 type, or can use 2 or more types together. Although the amount of the fluidity improver used is not particularly limited, it is preferably 0.1 to 3.0 parts by weight with respect to 100 parts by weight of the toner.

  The toner of the present invention can be used as a one-component developer by itself, but can also be used as a two-component developer by mixing with a carrier. The carrier is not particularly limited, and those commonly used in this field can be used. As the carrier, known magnetic particles can be used. Specific examples of the magnetic particles include metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead. Among these, ferrite is preferable.

Also, a carrier in which magnetic particles are coated with a resin, or in which magnetic particles are dispersed in a resin (resin dispersion type carrier) may be used as a carrier. Although there is no restriction | limiting in particular as resin which coat | covers a magnetic particle, For example, an olefin resin, a styrene resin, a styrene-acrylic resin, a silicone resin, ester resin, a fluorine-containing polymer system resin etc. are mentioned. Moreover, although it does not restrict | limit especially as resin for a resin dispersion type carrier, For example, a styrene acrylic resin, a polyester resin, a fluorine resin, a phenol resin etc. are mentioned. The usage ratio of the toner and carrier in the two-component developer is not particularly limited and can be appropriately selected according to the type of toner and carrier. However, if a resin-coated carrier (density 5 to 8 g / cm ² ) is taken as an example, development The toner may be used so that the toner is contained in 2 to 30% by weight, preferably 2 to 20% by weight of the total amount of the developer. In the two-component developer of the present invention, the coverage of the carrier with the toner is preferably 40 to 80%.

(Example)
EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not particularly limited as long as it does not exceed the gist thereof. In the following, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified. In the examples and comparative examples, the glass transition point (Tg) of the binder resin, the softening point (Tm) of the binder resin, the melting point of the release agent, the SP value of the release agent, the average dispersion diameter of the release agent, The volume average particle diameter and the average circularity of the toner were measured as follows.

[Glass transition point of binder resin (Tg)]
Using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.), a DSC curve is measured by heating 1 g of a sample at a heating rate of 10 ° C. per minute in accordance with Japanese Industrial Standard (JIS) K7121-1987. did. Draw the endothermic peak corresponding to the glass transition of the DSC curve obtained by extending the low-temperature base line to the high-temperature side and the point where the slope is maximum with respect to the curve from the peak to the peak. The temperature at the intersection with the tangent was determined as the glass transition point (Tg).

[Softening point of binder resin (Tm)]
Using a flow characteristic evaluation apparatus (trade name: Flow Tester CFT-100C, manufactured by Shimadzu Corporation), a load of 10 kgf / cm ² (9.8 × 10 ⁵ Pa) was applied so that 1 g of a sample was extruded from a die (nozzle). ), The temperature at a heating rate of 6 ° C. per minute was obtained, and the temperature at which half of the sample flowed out of the die was determined as the softening point. A die having a diameter of 1 mm and a length of 1 mm was used.

[Melting point of release agent]
Using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.), 1 g of the sample was heated from a temperature of 20 ° C. to 150 ° C. at a heating rate of 10 ° C. per minute, and then rapidly cooled from 150 ° C. to 20 ° C. The operation was repeated twice and the DSC curve was measured. The temperature at the top of the endothermic peak corresponding to the melting of the DSC curve measured in the second operation was determined as the melting point of the release agent.

[SP value of release agent]
The SP value is measured by the method of Sue, Clark (SUH, CLARKE) (by KWSuh, DHClarke), “Cohesive Energy Densities of Polymers from Turbidimetric Titrations”, Journal of Polymer Science (Journal of Polymer Science). Polymer Science), A-1, vol. 5, 1967, p.1671-1681), and was measured as follows.

  0.5 g of the mold release agent to be measured is weighed into a 100 ml beaker, 10 ml of a good solvent (mixed solution of dioxane and acetone) is added with a whole pipette, and dissolved by stirring with a magnetic stirrer. A mixed solution of n-hexane and ion-exchanged water) was dropped using a 50 ml burette, and the point at which the turbidity occurred at a measurement temperature of 20 ° C. was defined as a dropping amount.

From the measured value, the SP value δ of the release agent was determined by the following formula (3).
δ = (Vl / 2δl + Vh / 2δh) / (Vl / 2 + Vh / 2) (3)
In Formula (3), Vl is the molecular volume (ml / mol) of the solvent in the low SP solvent (hydrophobic solvent) mixed system, and Vh is the molecular volume of the solvent in the high SP solvent (good solvent) mixed system ( ml / mol), δl is the SP value of the solvent in the low SP solvent (hydrophobic solvent) mixed system, and δh is the SP value of the solvent in the high SP solvent (good solvent) mixed system.

[Average dispersion diameter of release agent]
The solidified product obtained by embedding the toner particles after the spheronization step and before the elution step in a room temperature curable epoxy resin is made into an ultrathin section with a thickness of about 100 μm using a microtome having diamond teeth. After dyeing with ruthenium oxide, the cross-section of the toner is observed at 20000 times with a transmission electron microscope (TEM, trade name: H-8100, manufactured by Hitachi, Ltd.) to confirm the dispersion state and the longest diameter of the wax domain. did. The longest diameter of 10 wax domains per toner particle was measured, and the number average value of the longest diameters of wax domains measured for 100 toner particles was taken as the average dispersion diameter of the release agent.

[Volume average particle diameter of toner]
In a 100 mL beaker, 20 mL of a 1% aqueous solution (electrolytic solution) of sodium chloride (first grade) was added, 0.5 mL of alkylbenzene sulfonate (dispersant) and 3 mg of a toner sample were sequentially added thereto, and ultrasonically dispersed for 5 minutes. . To this, a 1% aqueous solution of sodium chloride (first grade) was added so that the total amount would be 100 mL, and again ultrasonically dispersed for 5 minutes was used as a measurement sample. For this measurement sample, a Coulter Counter TA-III (trade name, manufactured by Coulter, Inc.) was used, and the measurement was performed under the conditions of an aperture diameter of 100 μm and a measurement target particle diameter of 2 to 40 μm on a number basis. Calculated.

[Average circularity of toner]
The circularity (ai) of the toner particles is defined by the above formula (1). The circularity (ai) as defined in the above formula (1) is measured by using, for example, a flow type particle image analyzer “FPIA-3000” manufactured by Sysmex Corporation. Further, the sum of the respective circularities (ai) measured for m toner particles is obtained, and the arithmetic average value obtained by the above equation (2) obtained by dividing the sum by the number of toner particles m is used as the average circularity (a ).

Example 1
[Toner particle preparation process]
[Pre-mixing process]
80 parts of polyester (binder resin, trade name: Tufton TTR-5, manufactured by Kao Corporation, glass transition point (Tg) 60 ° C., softening point (Tm) 100 ° C.), C.I. I. 12 parts of a master batch containing 40% Pigment Red 57: 1 as a colorant, an ester wax (release agent, trade name: Nissan Electol WE-5, manufactured by Nippon Oil & Fats, melting point 82 ° C., SP value 8.5-12) 3 parts, 5 parts of paraffin wax (release agent, trade name: HNP11, manufactured by Nippon Seiki Co., Ltd., melting point 68 ° C., SP value 6-8), α-olefin-anhydrous maleic as a dispersion aid for the release agent 3 parts of a copolymer of an acid copolymer and maleic anhydride monoester (trade name: Ceramer 1608, manufactured by Toyo Petrolite Co., Ltd.) and 2 parts of a charge control agent (trade name: N4P, manufactured by Clariant Co., Ltd.) 45 kg of the toner raw material contained in this blending ratio (part) was mixed for 10 minutes by a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.).

[Melt-kneading process]
The raw material mixture was melt-kneaded with an open roll type continuous kneader (trade name: MOS320-1800, manufactured by Mitsui Mining Co., Ltd.). The setting conditions of the open roll at this time were a heating roll supply side temperature of 140 ° C., a discharge side temperature of 70 ° C., a cooling roll supply side temperature of 80 ° C., and a discharge side temperature of 15 ° C. As the heating roll and the cooling roll, a roll having a diameter of 320 mm and an effective length of 1550 mm was used, and the gap between the rolls on the supply side and the discharge side was 0.3 mm. The rotation speed of the heating roll was 75 rpm, the rotation speed of the cooling roll was 65 rpm, and the supply amount of the toner raw material was 30 kg / h.

[Crushing and classification process]
After the melt-kneaded product was cooled to room temperature, it was roughly pulverized with a cutter mill (trade name: VM-16, manufactured by Orient Corporation). Subsequently, the coarsely pulverized product obtained by the coarse pulverization is finely pulverized by a counter jet mill (trade name: AFG, manufactured by Hosokawa Micron Corporation), and then by a rotary classifier (trade name: TSP separator, manufactured by Hosokawa Micron Corporation). The excessively pulverized toner was classified and removed.

[Spheronization process]
The pulverized product obtained in the pulverization / classification step was treated with a hybridization system (trade name: NHS-1 type, manufactured by Nara Machinery Co., Ltd.) at a peripheral speed of 80 m / s for 10 minutes.

[Elution process]
Into a 2 L beaker, 100 parts of n-hexane (manufactured by Kishida Chemical Co., Ltd., SP value 7.3) and a stirrer were added, and while stirring with a stirrer, 5 parts of the toner particles obtained in the toner particle preparation step were placed. The ultrasonic vibrating rod was immersed in the container and stirred for 10 seconds while vibrating at 28 kHz to remove the release agent exposed on the toner surface. Thereafter, the dispersion was subjected to suction filtration, and the toner remaining on the filter paper was dried in a constant temperature and humidity chamber of 35 ° C./5% RH to obtain the toner of Example 1. The obtained toner had a volume average particle diameter of 6.7 μm and an average circularity of 0.960. The filter paper (manufactured by ADVANTEC) used was a material polytetrafluoroethylene (abbreviated as PTFE) and a mesh diameter of 0.2 μm.

  Thereafter, 0.2 part of hydrophobic silica (trade name: R-974, manufactured by Nippon Aerosil Co., Ltd.) and hydrophobic titanium (trade name: T-805, manufactured by Nippon Aerosil Co., Ltd.) with respect to 100 parts of toner particles. The toner of Example 1 was obtained by adding 0.3 part and mixing with a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.). It was confirmed that 3.1 parts of paraffinic wax was present in the toner of Example 1.

(Example 2)
Of the toner raw materials, paraffin wax (release agent, trade name: HNP11, manufactured by Nippon Seiki Co., Ltd., melting point 68 ° C., SP value 6-8) is used instead of paraffin wax (release agent, trade name: The toner of Example 2 (volume average particle diameter is 6.9 μm, average), except that HNP10, manufactured by Nippon Seiki Co., Ltd., melting point 75 ° C., SP value 6 to 8) was used. The degree of circularity was 0.960, and the remaining amount of paraffinic wax was 3.3 parts).

(Example 3)
The toner material contains 4 parts of paraffinic wax (release agent, trade name: HNP11, manufactured by Nippon Seiki Co., Ltd., melting point 68 ° C., SP value 6-8), and the toner contains 2.6 paraffinic wax. The toner of Example 3 (volume-average particle size is 6.7 μm, average circularity is 0.957, and the residual amount of paraffinic wax is 2.6, in the same manner as in Example 1, except that a portion of the wax remained. Part).

Example 4
Of the toner raw materials, instead of ester wax (release agent, trade name: Nissan Electol WE-5, manufactured by Nippon Oil & Fats, melting point 82 ° C., SP value 8.5-12), ester wax (release agent) , Trade name: Nissan Electol WE-3, manufactured by Nippon Oil & Fats Co., Ltd., melting point 73 ° C., SP value 8.5-12). The volume average particle diameter was 6.5 μm, the average circularity was 0.958, and the residual amount of paraffin wax was 3.0 parts).

(Example 5)
A toner of Example 5 was obtained in the same manner as in Example 1 except that the spheroidizing treatment was not performed. The obtained toner had a volume average particle size of 6.7 μm, an average circularity of 0.951, and a residual amount of paraffin wax of 3.1 parts.

(Example 6)
A toner of Example 6 was obtained in the same manner as in Example 1 except that the elution process was changed as follows.

[Elution process]
In a 2 L beaker, 100 parts of n-hexane (manufactured by Kishida Chemical Co., Ltd., SP value 7.3) and a stirrer are put, and 5 parts of the toner particles obtained in the toner particle preparation step are placed while stirring with a stirrer. The mixture was stirred for 2 seconds to remove the release agent exposed on the toner surface. Thereafter, the dispersion was subjected to suction filtration, and the toner remaining on the filter paper was dried in a constant temperature and humidity chamber of 35 ° C./5% RH to obtain the toner of Example 6. The obtained toner had a volume average particle diameter of 6.7 μm, an average circularity of 0.960, and a residual amount of paraffin wax of 4.1 parts. The filter paper (manufactured by ADVANTEC) used was a material polytetrafluoroethylene (abbreviated as PTFE) and a mesh diameter of 0.2 μm.

(Comparative Example 1)
The toner of Comparative Example 1 (volume average particle size is 6.7 μm, average circularity is 0.960, and the remaining amount of paraffin wax is 5 parts in the same manner as in Example 1 except that the elution treatment is not performed. )

(Comparative Example 2)
The toner material does not contain ester wax (release agent, trade name: Nissan Electol WE-5, manufactured by Nippon Oil & Fats, melting point 82 ° C., SP value 8.5-12), and paraffin wax (release agent, Product name: HNP10, manufactured by Nippon Seiki Co., Ltd., melting point 75 ° C., SP value 6-8), except that it contains 7 parts of toner of Comparative Example 2 (volume average particle size is 6). 0.8 μm, the average circularity was 0.958, and the residual amount of paraffin wax was 4.3 parts).
Table 1 shows physical property values and the like of the toners of Examples and Comparative Examples.

  The toners of Examples and Comparative Examples produced as described above were evaluated for cleaning properties, charging properties, storage properties, fixing properties, and transfer properties.

[Cleanability]
A two-component developer in which 5 parts of toner are mixed with 95 parts of a ferrite core carrier having a volume average particle diameter of 45 μm is charged into a color composite machine (trade name: MX-2700, manufactured by Sharp Corporation), and the Japanese Industrial Standard (JIS). A chart with a printing rate of 5% was continuously printed on an A4 size recording paper defined in P0138, and a test chart was formed after printing 30,000 sheets. Three types of test charts were formed: a full-color image, a fine line chart, and white paper (printing rate 0%). The image defects of these three types of test charts were visually confirmed and evaluated. The evaluation criteria are as follows.
○: Good. There are no image defects in all three types of test charts.
×: Unusable. An image defect has occurred in one or more types of test charts.

[Chargeability]
5 parts of toner is mixed with 95 parts of a ferrite core carrier having a volume average particle diameter of 45 μm and stirred for 30 minutes in a table-top ball mill (manufactured by Tokyo Glass Instrument Co., Ltd.) in a normal temperature and humidity environment at a temperature of 25 ° C. and a relative humidity of 50%. Then, the initial toner charge amount was measured. Further, the charge amount of the toner after printing 10,000 sheets of a text chart with a printing rate of 6% was measured with a color composite machine (trade name: MX-2700, manufactured by Sharp Corporation) using a two-component developer containing the processed toner.

  The toner charge amount is measured using a charge amount measuring device (trade name: 210HS-2A, manufactured by Trek Japan Co., Ltd.), and a mixture of carrier particles and toner collected from the inside of a ball mill, with a 500 mesh conductive layer at the bottom. In a metal container equipped with a magnetic screen, and sucking only toner with a suction device at a suction pressure of 250 mmHg, and the weight difference between the weight of the mixture before suction and the weight of the mixture after suction, and a condenser connected to the container The toner charge amount was determined from the potential difference between the electrode plates. The evaluation criteria are as follows.

The ratio between the initial charge amount and the charge amount after printing 1000 sheets is preferably as small as possible.
Specifically, it is calculated by the following formula (4).
(Charge amount change rate) = (Charge amount after printing) / (Initial charge amount) × 100 (4)
○: Charge amount change rate is 80% or more. There is no substantial degradation in image quality due to a decrease in charge amount.
X: Charge amount change rate is less than 80%. There is a substantial decrease in image quality due to a decrease in charge amount.

[Preservation]
Before and after the treatment, 28 to 30 g of each is put into three 50 ml plastic bottles. With the lid of the plastic bottle closed, the bottle is placed in a constant temperature and humidity chamber at 50 ° C./10% RH, taken out every 24 hours, and the bulk density of the toner is measured. Initial, 24 hours, 48 hours, and 72 hours later, the bulk density is compared, and the toner with less fluctuation has better storage stability.

Specifically, the variation rate is calculated by the following equation (5).
(Variation rate) = (bulk density after 72 hours) / (initial bulk density) × 100 (5)
○: The fluctuation rate is 90% or more.
Δ: The fluctuation rate is 80% or more and less than 90%.
X: Fluctuation rate is less than 80%.

[Fixability]
Using a modified color multifunction device (trade name: MX-2700, manufactured by Sharp Corporation), recording paper (trade name: PPC paper SF-4AM3, manufactured by Sharp Corporation) as a recording medium is 20 mm long and wide. A sample image including a 50 mm rectangular magenta solid image portion is adjusted so that the amount of toner adhering to the recording paper in an unfixed state in the solid image portion is 0.5 mg / cm ^2. And a fixed image was prepared using an external fixing device prepared using a fixing unit of a color multifunction peripheral. The fixing process speed was 124 mm / second, the temperature of the fixing roller was increased from 130 ° C. in increments of 5 ° C., and the temperature range in which neither low temperature offset nor high temperature offset occurred was defined as the non-fixing offset region.

Further, the definition of high temperature and low temperature offset is defined as the occurrence of an offset when toner is not fixed on the recording paper during fixing, but is attached to the recording paper after the roller has made a full turn while adhering to the fixing roller.
A: Fixing non-offset region is 60 ° C. or higher. ○: Fixing non-offset region is 45 ° C. or higher and lower than 60 ° C.
Δ: Fixing non-offset region is 35 ° C. or higher and lower than 45 ° C.
X: The fixing non-offset region is less than 35 ° C.

[Transferability]
Using a modified color MFP (trade name: MX-2700, manufactured by Sharp Corporation), a sample image including a magenta solid image portion having a rectangular shape of 100 mm length and 50 mm width is exposed to toner in the solid image portion. An image was formed by adjusting the adhesion amount on the body to 0.6 mg / cm ² , and the ratio of the toner on the photosensitive member transferred onto the transfer belt was defined as the transfer rate.
○: Transfer rate is 95% or more.
Δ: Transfer rate is 80% or more and less than 95%.
X: Transfer rate is less than 80%.

〔Comprehensive evaluation〕
◎: The highest level of all items (“○”, fixing test “◎”)
○: Only one “△ (○ for fixing test)”.
Δ: There is no “x”, but there are two or more “Δ (○ in case of fixing test)”.
×: There is at least one “×”.

  Table 2 shows the evaluation. The toners of Examples 1 to 5 and Comparative Example 2 were evaluated for cleaning properties, electrification, and storage properties. The paraffinic wax exposed on the toner surface was removed by the elution treatment, and appropriate irregularities were formed on the toner surface. Since it was formed, both were good. The toner of Example 6 had good cleaning properties and charging properties, but the storage stability was at a practical level. Since the toner of Comparative Example 1 was not subjected to the elution treatment, all of them were defective.

  The toners of Examples 1, 5 and 6 and Comparative Example 1 were evaluated for fixability because the melting point of the paraffin wax was 70 ° C. or lower and the melting point of the ester wax was 80 ° C. or higher. Wide area and non-high temperature offset area. Since the toner of Example 2 has a melting point of paraffinic wax of 70 ° C. or higher, and the toner of Example 3 has a low content of paraffinic wax having a melting point of 70 ° C. or lower, the non-low temperature offset region is narrow. . In the toner of Example 4, the melting point of the ester wax is 80 ° C. or less, and since the toner of Comparative Example 2 does not contain the ester wax, the non-high temperature offset region is narrow.

  In the transferability evaluation, in Example 5, since the average circularity of the toner is less than 0.955, the shape of the toner surface becomes non-uniform, and the toner developed on the photosensitive member is transferred onto the medium by electrostatic force. The transfer rate to be moved was low.

3 is a cross-sectional view schematically illustrating an example of the toner of the present invention. FIG. FIG. 6 is a process diagram illustrating a procedure of a toner manufacturing method according to an embodiment of the present invention. It is the schematic explaining an elution process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Toner particle 1b Toner 2 Binder resin 3a Paraffin type wax 3b Ester type or carnauba type wax 4 Container 5 Solvent 6 Stirrer 7 Filtration suction device 8 Filtration filter 9 Precipitate

Claims (13)

A toner comprising at least a binder resin, a colorant, and two or more release agents having different solubility in a solvent having a solubility parameter of 7.5 or less,
Of the release agents present in a region having a depth of 700 nm or less from the toner surface, the release agent having higher solubility in the solvent is removed by elution into the solvent. Toner. The difference between the solubility parameter of the release agent having the higher solubility in the solvent and the solubility parameter of the solvent is 0.5 or less,
The toner according to claim 1, wherein a difference between a solubility parameter of a release agent having a lower solubility in the solvent and a solubility parameter of the solvent is 1 or more.   The toner according to claim 1, wherein the solvent is at least one selected from n-hexane and n-heptane.   The toner according to claim 1, wherein an average circularity of the toner is 0.955 or more.   The toner according to claim 1, wherein the binder resin includes polyester and a polyester-vinyl hybrid resin.   Furthermore, it contains a copolymer of an α-olefin-maleic anhydride copolymer and a maleic anhydride monoester as a dispersing aid for the mold release agent. Toner.   The toner according to claim 1, wherein the release agent contains at least one selected from ester waxes and carnauba waxes, and paraffin wax.   The toner according to claim 7, wherein the paraffin wax is present in an amount of 3 parts by weight or more in a region having a depth of more than 700 nm from the toner surface.   The toner according to claim 7, wherein the paraffin wax has a melting point of 70 ° C. or less.   The toner according to claim 7, wherein the melting point of the ester wax and the carnauba wax is 80 ° C. or higher. A toner production method for producing the toner according to claim 1,
At least a pre-mixing step of mixing two or more release agents having different solubility in a solvent having a binder resin, a colorant, and a solubility parameter of 7.5 or less;
A melt-kneading step of melt-kneading the mixture obtained by premixing,
A pulverization / classification step of pulverizing and classifying the melt-kneaded product obtained by melt-kneading;
A spheronization step of spheronizing the pulverized product obtained by pulverization and classification;
An elution step of treating the toner particles obtained by spheroidization in the solvent to elute the release agent having higher solubility in the solvent among the release agents contained in the toner particles;
A method for producing a toner, comprising:   12. The release agent having higher solubility in the solvent among the release agents contained in the toner particles is eluted by irradiating ultrasonic waves in the elution step. Toner production method.   In the elution step, 1 to 10 parts by weight of the toner particles are added to 100 parts by weight of the solvent, and the release agent having higher solubility in the solvent among the release agents contained in the toner particles. The toner production method according to claim 11, wherein the toner is eluted.