JP2007178669A - Method for manufacturing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a toner by which a toner capable of preventing hot offset and having a narrow particle size distribution can be manufactured without using an organic solvent. <P>SOLUTION: The toner is manufactured by carrying out a melt kneading step (s1) of melt-kneading raw materials including a binder resin, a colorant, a release agent and a compatibilizer which compatibilizes the binder resin and the release agent to disperse the raw materials except the binder resin in the binder resin, and a granulation step (s3) of obtaining toner particles by softening the binder resin in a resin kneaded material obtained at the melt kneading step in an aqueous medium comprising a dispersant and water, and dispersing the resin kneaded material in the aqueous medium to produce toner particles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a toner manufacturing method.

  As an image forming apparatus such as a printer, a facsimile machine, and a copying machine, an image forming apparatus that forms an image using electrophotography has been proposed. In an image forming apparatus using an electrophotographic method, after forming an electrostatic charge image by various means on the surface of an electrophotographic photosensitive member (hereinafter, also simply referred to as “photosensitive member”) provided with a photosensitive layer containing a photoconductive substance, An image is formed by supplying toner to the surface of the photoreceptor to develop the electrostatic image, and transferring and fixing the formed toner image onto a recording medium such as paper.

  A toner used for developing an electrostatic image is formed by dispersing a colorant in a resin having a binding property called a binder resin, and includes various additives such as a charge control agent as necessary. The toner is charged by frictional charging, is carried on a developing roller, and is supplied to the surface of the photoreceptor.

  The method for producing the toner used for image formation as described above is roughly classified into a dry method and a wet method. As a dry method, for example, a binder resin, a colorant and the like are melt-kneaded and dispersed in a softened binder resin, and the solidified product of the obtained resin kneaded material is mechanically pulverized. Examples thereof include a pulverization method for obtaining particles and obtaining toner. Although the dry method is widely used industrially, the shape of the resulting toner particles becomes indefinite by mechanically pulverizing the solidified product of the melt-kneaded product, so that the toner in the container containing the toner The fluidity of As a result, the charging performance of the toner is lowered, and the charge amount of the toner charged by frictional charging is reduced. In the dry method, it is necessary to perform classification after pulverization of the resin kneaded product, and toner particles that do not have a desired particle size are discarded.

  As a wet method, for example, there is a method in which a binder resin and a colorant are dispersed or dissolved in an organic solvent and granulated to produce toner particles to produce a toner. Examples of such a wet method include a dissolution suspension method and an emulsification dispersion method. In the dissolution suspension method, for example, a binder resin and a colorant are dissolved or dispersed in an organic solvent in which the binder resin can be dissolved, and the resulting solution or dispersion and a hardly water-soluble alkaline earth metal salt, etc. After mixing with an aqueous dispersion in which the inorganic dispersant is dispersed in water and granulating, the organic solvent is removed to obtain a toner. In the emulsification dispersion method, for example, a binder resin and a colorant are dissolved or dispersed in an organic solvent in which the binder resin can be dissolved, and the resulting solution or dispersion is emulsified and dispersed in an aqueous dispersion. The toner is obtained by removing the organic solvent.

  Such wet methods also have problems to be solved. For example, since the organic solvent is used for dissolving the binder resin in the dissolution suspension method and the emulsification dispersion method as exemplified above, a small amount of the organic solvent remains in the obtained toner particles. There is a problem that the dispersion state and composition of the components change from preparation to preparation, and the charging performance of the toner particles varies. Further, when an organic solvent is used, the amount of each component contained in the toner particles, that is, the composition of the toner particles varies depending on the solubility of the binder resin in the organic solvent, so that a toner having desired characteristics is manufactured with good reproducibility. It is difficult. Further, when an organic solvent having a large environmental load is used as the organic solvent, a processing facility for appropriately treating the removed organic solvent is required, which increases the manufacturing cost of the toner.

  As a method for producing a toner capable of solving various problems caused by using such an organic solvent, a wet method for producing a toner without mechanically crushing the solidified product of the resin kneaded material is used, and an organic solvent is used. A method by which the toner can be produced without using it has been proposed by the present applicant (see, for example, Patent Documents 1 and 2).

  In the method for producing a toner disclosed in Patent Document 1, a mixture obtained by mixing a resin kneaded material obtained by melt kneading and an aqueous dispersion of a calcium carbonate salt that is hardly water-soluble and acid-decomposable is heated, and the surface is heated. After producing toner particles coated with calcium carbonate, the toner is manufactured by adjusting the pH of the aqueous dispersion to acidity and decomposing and removing calcium carbonate on the surface of the toner particles. In the method for producing a toner disclosed in Patent Document 2, a mixture obtained by mixing a resin kneaded product obtained by melt kneading and an aqueous dispersant solution, which is an aqueous solution of a water-soluble polymer dispersant, is heated, The toner is produced by generating toner particles.

  According to the toner production methods disclosed in Patent Documents 1 and 2, the granulation of the resin kneaded product is carried out by using an aqueous dispersion or an aqueous dispersant solution (hereinafter, the aqueous dispersion and aqueous dispersant solution are collectively referred to as an aqueous medium). Therefore, a toner having a spherical shape and excellent fluidity can be produced without causing various problems caused by using the organic solvent.

  The toner used for developing the electrostatic image contains a release agent such as wax for the purpose of preventing high temperature offset. High temperature offset is a heat roller fixing method in which toner is fixed by heating the toner with a fixing heating roller. During fixing, the toner is excessively melted, and a part of the melted toner is fused to the fixing heating roller. To be removed. For example, when a toner is produced from a resin kneaded product containing a binder resin and a colorant, the release agent is melt-kneaded together with the binder resin and the colorant and dispersed in the binder resin.

  In a method in which a binder resin is heated and softened as in melt kneading to disperse a colorant, a release agent and the like in the binder resin, not only the binder resin but also the release agent is softened. The softened release agent aggregates with each other in the resin kneaded material to form a domain. As described above, since the release agent aggregates in the resin kneaded material, it is very difficult to disperse the release agent in the binder resin when the release agent and the binder resin are not compatible. .

  When a toner is produced from a resin kneaded product having poor dispersibility of the release agent in the binder resin by a production method as disclosed in Patent Documents 1 and 2, the mixture of the aqueous medium and the resin kneaded material is heated. As a result, the release agent is more easily aggregated, and the dispersibility of the release agent in the generated toner particles is further reduced. Further, the agglomerated release agent is easily detached from the resin kneaded product and the toner particles, and the content of the release agent contained in the manufactured toner is higher than the content of the release agent contained in the resin kneaded product before granulation. Lower. When the content of the release agent is reduced due to the release of the release agent, the release property of the toner with respect to the heating roller cannot be sufficiently exhibited in the heat roller fixing method, and high temperature offset cannot be prevented. .

  Patent Documents 1 and 2 neither disclose nor suggest a method for solving such a problem. Therefore, there is a need for a method that prevents the release agent from being detached and does not lower the content of the release agent contained in the manufactured toner as compared with the content of the release agent contained in the resin kneaded product.

JP 2005-148406 A Japanese Patent Laid-Open No. 2005-165039

  An object of the present invention is to provide a toner manufacturing method capable of manufacturing a toner capable of preventing high temperature offset without using an organic solvent.

The present invention softens the binder resin by melt-kneading a raw material containing a binder resin, a colorant, a release agent, and a compatibilizer for compatibilizing the binder resin and the release agent. A melt-kneading step for dispersing raw materials other than the binder resin in the binder resin;
Granulation to obtain toner particles by softening the binder resin of the resin kneaded product obtained by the melt-kneading step in an aqueous medium containing a dispersant and water and dispersing the resin kneaded material in the aqueous medium to form particles A process for producing a toner comprising the steps of:

In the present invention, the compatibilizer is
The raw material is contained in 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.

In the present invention, the release agent is contained in the 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.
The compatibilizer is characterized by being contained in the raw material at a ratio of 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the release agent.

In the present invention, the binder resin is a polyester resin.
In the present invention, the dispersant is a water-soluble polymer compound.

  According to the present invention, in the melt-kneading step, the raw material containing the binder resin and the release agent is melt-kneaded together with the compatibilizer for compatibilizing the binder resin and the release agent. The mold agent is compatible with each other and aggregation of the release agent is prevented. Thereby, the dispersibility of the release agent in the binder resin can be improved. The melt-kneading is to at least soften the binder resin and disperse raw materials other than the binder resin in the binder resin. Softening includes melting (melting).

  In the granulation step, the resin kneaded product obtained by the melt kneading step, which is excellent in dispersibility in the binder resin of the release agent, is dispersed in an aqueous medium to produce toner particles. Therefore, the release agent can be finely dispersed inside the toner particles. As a result, a large amount of aggregated release agent can be prevented from being detached from the toner particle surface. In addition, in order to soften the binder resin in the resin kneaded product in the granulation process, even if the release agent in the resin kneaded product has a melting point or higher and the release agent tends to aggregate, the presence of the compatibilizing agent Since aggregation of the release agent is prevented, a decrease in dispersibility of the release agent in the resin kneaded product can be prevented. As a result, release of the release agent from the toner particles can be further suppressed, and the content of the release agent contained in the toner particles is lower than the content of the release agent contained in the resin kneaded product. Can be prevented. Further, since the release amount of the release agent from the toner particles is reduced, it is possible to obtain toner particles having a preferable release agent content by including an appropriate amount of the release agent in the raw material. As a result, the temperature at which the high temperature offset phenomenon does not occur can be increased, and a toner having a wide non-offset region can be obtained.

  In the granulation step, the resin kneaded product is granulated by dispersing the resin kneaded product in an aqueous medium without mechanically pulverizing and granulating the solidified product of the resin kneaded product, so that the shearing force acting on the resin kneaded product is reduced. It can be made uniform. As a result, a well-shaped toner can be obtained. Further, since the resin kneaded material is dispersed in the aqueous medium at least in a state in which the binder resin is softened, particles having no corners as toner particles, that is, particles having a shape close to a spherical shape and excellent in fluidity can be obtained. Further, in the granulation step, in order to soften the binder resin in the resin kneaded product, for example, a mixture of the aqueous medium and the resin kneaded product is heated. Thus, a toner having a certain performance can be stably manufactured. In addition, since it is not necessary to use an organic solvent that has a large environmental load in the production of toner, a processing facility for appropriately treating the organic solvent is not required.

  According to the present invention, the compatibilizing agent is contained in the 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. When the proportion of the compatibilizer is less than 1 part by weight with respect to 100 parts by weight of the binder resin, the content of the compatibilizer 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 compatibilizer 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. Therefore, when the compatibilizer is contained in such a ratio, the binder resin and the release agent are made compatible to prevent the release agent from agglomerating, and the dispersibility of the release agent in the binder resin is increased. This can be further improved.

  Further, according to the present invention, the release agent is contained in the 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, and the compatibilizing agent is contained in the raw material. Since it is contained at a ratio of 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the agent, the ratios of the binder resin, the release agent and the compatibilizing agent are suitably set. Compatibility with the agent can be further improved.

  According to the invention, the binder resin is a polyester resin. In the toner production method of the present invention, toner particles are produced by melting and dispersing a resin kneaded material containing a binder resin in an aqueous medium, and therefore, producing toner particles containing a polyester resin as the binder resin. Can do. Thus, a toner containing a polyester resin as the binder resin and having excellent fluidity and fixability can be obtained. Further, since the polyester resin is excellent in translucency and excellent in secondary color reproducibility, a toner suitable as a color toner can be obtained.

  According to the invention, the dispersant is a water-soluble polymer compound. By using a water-soluble polymer compound as the dispersant, the dispersant adhering to the toner particles can be removed by a simple operation of washing with water, which is excellent in productivity and industrially advantageous. .

  FIG. 1 is a process diagram showing a procedure of a toner manufacturing method according to an embodiment of the present invention. The method for producing the toner of the present invention includes a binder resin, a colorant, a mold release agent, and a raw material containing a binder resin and a compatibilizer for compatibilizing the mold release agent. A melt-kneading step of softening the resin to disperse raw materials other than the binder resin in the binder resin, and a binder resin of a resin kneaded product obtained by the melt-kneading step in an aqueous medium containing a dispersant and water And a granulating step of dispersing the resin kneaded material in an aqueous medium to form particles, thereby obtaining toner particles.

  In the present embodiment, an aqueous medium preparation step, a cooling step, a washing step, a separation step, and a drying step are further included. That is, the toner manufacturing method according to the present embodiment includes a melt-kneading step (step s1), an aqueous medium preparation step (step s2), a granulation step (step s3), a cooling step (step s4), and a washing step. (Step s5), a separation step (Step s6), and a drying step (Step s7). In the toner manufacturing method according to the present embodiment, after starting in step s0, step s1 or step s2 is performed. Any of the melt-kneading process of step s1 and the aqueous medium preparation process of step s2 may be performed first. Further, the cleaning process in step s5 may be performed after the separation process in step s6 and before the drying process in step s7.

[Melting and kneading process]
In the melt-kneading step of step s1, the binding is performed by melt-kneading a raw material containing a binder resin, a colorant, a release agent, and a compatibilizer for compatibilizing the binder resin and the release agent. The resin is softened and raw materials other than the binder resin are dispersed in the binder resin. The raw material may contain an additive such as a charge control agent. The additive is melt-kneaded together with the binder resin, the colorant, the release agent, and the compatibilizer, and dispersed in the binder resin.

(A) Binder Resin The binder resin is not particularly limited as long as it is a resin that can be melted by heating, and examples thereof include a polyester resin, a polyurethane resin, an epoxy resin, and an acrylic resin. One of these resins may be used alone, or two or more thereof may be used in combination. Moreover, even if it is the same kind of resin, it is possible to use a plurality of kinds of resins different in any one or more in terms of molecular weight, monomer composition, and the like.

  Among the above-mentioned resins, polyester resin is preferable in consideration of fluidity of the obtained toner particles in the developing device, low-temperature fixability, and the like. A polyester resin is suitable as a binder resin for a color toner because it can realize a color toner having excellent translucency and excellent secondary color reproducibility. Further, since the polyester resin is softened at a lower temperature than the other resins exemplified above, it is possible to easily generate toner particles in the granulation process in step s3.

  The polyester resin is not particularly limited, and examples thereof include polycondensation products of polybasic acids and polyhydric alcohols. Here, polybasic acids are polybasic acids and derivatives thereof, such as acid anhydrides or esterified products of polybasic acids. Polyhydric alcohols are compounds having two or more hydroxyl groups, and include both alcohols and phenols.

  As polybasic acids, those commonly used as monomers of polyester resins can be used, for example, aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid, Examples thereof include aliphatic carboxylic acids such as maleic anhydride, fumaric acid, succinic acid, and adipic acid. Polybasic acids can be used alone or in combination of two or more.

  Polyhydric alcohols that are commonly used as monomers for polyester resins can also be used. For example, aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, glycerin, cyclohexanediol, Examples include alicyclic polyhydric alcohols such as cyclohexanedimethanol and hydrogenated bisphenol A, aromatic diols such as ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A. Here, bisphenol A is 2,2-bis (p-hydroxyphenyl) propane, and examples of the ethylene oxide adduct of bisphenol A include polyoxyethylene-2,2-bis (4-hydroxy). Phenyl) propane and the like, and examples of the propylene oxide adduct of bisphenol A include polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane. Polyhydric alcohols can be used alone or in combination of two or more.

  The polyester resin can be synthesized by a condensation polymerization reaction. For example, it can be synthesized by subjecting a polybasic acid and a polyhydric alcohol to a polycondensation reaction, specifically a dehydration polycondensation reaction in the presence of a catalyst in an organic solvent or in the absence of a solvent. At this time, a methethanol polycondensation reaction may be performed using a methyl esterified product of a polybasic acid as a part of the polybasic acid. The polycondensation reaction between the polybasic acid and the polyhydric alcohol may be terminated when the acid value and softening point of the polyester resin to be produced reach predetermined values. In this polycondensation reaction, by appropriately changing the blending ratio of polybasic acids and polyhydric alcohols, the reaction rate, etc., for example, the content of carboxyl groups bonded to the terminal of the resulting polyester resin, and thus the resulting polyester The acid value of the resin can be adjusted, and other physical property values such as the softening point can be adjusted.

  Moreover, as a polyester resin, it is preferable that the acid value is 1 mgKOH / g or more and 40 mgKOH / g or less. The acid value is measured according to a potentiometric titration method described in Japanese Industrial Standard (JIS) K0070-1992.

  When the acid value of the polyester resin is less than 1 mgKOH / g, it is difficult to disperse the colorant in the binder resin, and there is a possibility that sufficient coloring power cannot be obtained. If the acid value of the polyester resin exceeds 40 mgKOH / g, the amount of moisture adsorbed in a high temperature and high humidity environment increases, and the moisture content of the toner may increase. As a result, the volume resistivity of the toner becomes low, and it becomes difficult to stably control the charge amount against environmental changes even when a charge control agent is added. When the acid value of the polyester resin is within the above range, a toner having a sufficient coloring power and a small change in charging performance even when there is an environmental variation can be produced.

  The binder resin preferably has a softening point of 150 ° C. or lower, and particularly preferably 60 ° C. or higher and 150 ° C. or lower. When the softening point of the binder resin is in such a range, the binder resin can be easily softened in the granulation process in step s3, and granulation can be easily performed. It becomes easy to disperse a colorant, a release agent and the like in the binder resin. When the softening point of the binder resin exceeds 150 ° C., it is necessary to increase the melt-kneading temperature in order to soften the binder resin, and the release agent is excessively melted by the increase of the melt-kneading temperature and contains a compatibilizing agent. Even if it makes it, it may become difficult to disperse the release agent in the binder resin. If the melt kneading temperature is lowered so that the release agent does not melt, the binder resin is not softened, and it may be difficult to disperse the colorant in the binder resin.

  If the softening point of the binder resin exceeds 150 ° C., the temperature of the mixture of the aqueous medium and the resin kneaded product needs to be higher than the softening point of the binder resin in the granulation step, and the temperature of the mixture is increased. Therefore, it is necessary to increase the pressure in the container for granulating. If the softening point of the binder resin is less than 60 ° C., the glass transition point (Tg) of the binder resin is likely to be close to room temperature, so that blocking occurs in which the toner thermally aggregates inside the image forming apparatus, The storage stability of the toner is lowered, and there is a risk of inducing printing failure and device failure.

  The glass transition point (Tg) of the binder resin is not particularly limited and can be appropriately selected from a wide range. However, considering the fixability and storage stability of the obtained toner, it is 30 ° C. or higher and 80 ° C. or lower. Is preferred. If the glass transition point (Tg) of the binder resin is less than 30 ° C., blocking in which the toner is thermally aggregated in the image forming apparatus is likely to occur, and storage stability may be deteriorated. When the glass transition point (Tg) of the binder resin exceeds 80 ° C., the fixability of the toner to the recording medium is lowered, and there is a possibility that fixing failure occurs.

(B) Colorant As the colorant mixed with the binder resin, any of dyes, organic pigments, inorganic pigments and the like used as toner colorants can be used. Examples of the colorant include the following colorants. In the following, C.I. I. Is a color index.

  Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, magnetite, and nonmagnetic ferrite and magnetic ferrite containing metal elements other than iron.

  Examples of yellow colorants include C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185.

  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 the red colorant include C.I. I. Pigment red 19, C.I. I. Pigment red 48: 3, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 150, C.I. I. And CI Pigment Red 184.

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

  Examples of the blue colorant 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. 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 white colorants include zinc white, titanium oxide, antimony white, and zinc sulfide.

  One of these colorants may be used alone, or two or more of different colors may be used in combination. Also, a plurality of colorants of the same color can be used in combination. In order to improve the dispersibility in the binder resin, the colorant is preferably contained in advance as a master batch in which the colorant is preliminarily dispersed in the binder resin.

  The ratio of the colorant to the binder resin is not particularly limited, and can be appropriately selected from a wide range according to various conditions such as the types of the binder resin and the colorant and the properties required for the toner particles to be obtained. The amount is preferably from 0.1 to 20 parts by weight, more preferably from 3 to 10 parts by weight, based on 100 parts by weight of the binder resin. When the use ratio of the colorant is within the above range, a toner having sufficient coloring power can be obtained.

  If the amount of the colorant used is less than 0.1 parts by weight, sufficient coloring power cannot be obtained, the amount of toner required to form an image having a desired image density increases, and toner consumption increases. There is a risk. When the proportion of the colorant used exceeds 20 parts by weight, the dispersibility of the colorant in the resin kneaded product is lowered, and there is a possibility that a toner having a uniform coloring power cannot be obtained.

(C) Release agent Examples of the release agent include wax. Examples of the wax include natural waxes such as carnauba wax and rice wax, synthetic waxes such as polypropylene wax, polyethylene wax and Fischer-Tropsch wax, coal waxes such as montan wax, petroleum waxes such as paraffin wax, alcohol waxes, Examples include ester waxes. A mold release agent may be used individually by 1 type, and 2 or more types may be used together.

  The mold release agent preferably has a melting point of 60 ° C. or higher and 130 ° C. or lower. When the melting point of the release agent is less than 60 ° C., the toner particles may aggregate in the image forming apparatus and storage stability may be reduced. When the melting point of the release agent exceeds 130 ° C., when the toner is fixed by heating with a heating roller, the release agent does not melt, and there is a possibility that a low temperature offset that does not fix the toner on the recording medium may occur. Therefore, when the melting point of the release agent is within the above preferable range, it is possible to obtain a toner that has excellent storage stability and can prevent low temperature offset.

  The release agent is preferably contained in a proportion 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. If the release agent is less than 1 part by weight, the releasability cannot be exhibited and high temperature offset may occur. If the release agent exceeds 10 parts by weight, filming that forms a thin film of the release agent on the surface of the photoreceptor may occur. Therefore, by setting the release agent in the above range, filming and high temperature offset can be prevented.

(D) Compatibilizer The compatibilizer is not particularly limited as long as the binder resin and the release agent are compatible. The binder resin and the release agent that are compatible with each other may be those that improve the compatibility between the binder resin and the release agent, and the binder resin and the release agent that are not compatible with each other. It may be compatible.

  The compatibilizer is preferably compatible with both the binder resin and the release agent. Examples of such a compatibilizing agent include a copolymer having a portion excellent in compatibility with wax and a portion excellent in compatibility with binder resin.

  As the compatibilizing agent, for example, a copolymer of a polyolefin part such as polyethylene having excellent compatibility with wax and a vinyl polymer part such as polystyrene or styrene-acrylic resin having excellent compatibility with the binder resin is used. It can be used as a solubilizer. Examples of such a compatibilizing agent include a styrene-ethylene-butadiene block copolymer, a styrene-methyl methacrylate block copolymer, an ethylene-styrene graft copolymer, and a styrene-maleic anhydride copolymer. .

  As the compatibilizing agent, a commercially available one can be used. Examples of commercially available compatibilizers include Ceramer 1608 and Ceramer 1251 (both trade names) manufactured by Toyo Petrolite Co., Ltd. Ceramer 1608 and ceramer 1251 are both copolymers of an α-olefin-maleic anhydride copolymer and a maleic anhydride monoester.

  The compatibilizing agent is preferably contained in the 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. By including the compatibilizing agent 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 compatibilizer is less than 1 part by weight with respect to 100 parts by weight of the binder resin, the content of the compatibilizer 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 compatibilizer 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 compatibilizing agent is contained in the raw material at the above-mentioned suitable ratio, and it is further preferable that it is contained at a ratio of 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the release agent. When the proportion of the compatibilizing agent is less than 0.1 parts by weight with respect to 100 parts by weight of the releasing agent, the content of the compatibilizing agent is smaller than the content of the releasing agent, preventing aggregation of the releasing agent. It may not be possible. When the proportion of the compatibilizer exceeds 10 parts by weight with respect to 100 parts by weight of the release agent, the release agent may be excessively dispersed in the binder resin.

(E) Additive As the additive, for example, a charge control agent can be used. As the charge control agent, those commonly used in this field can be used. For example, calixarenes, quaternary ammonium salt compounds, nigrosine compounds, organometallic complexes, chelate compounds, salicylic acid metal salts such as zinc salicylate, sulfones, etc. Examples thereof include a polymer compound obtained by homopolymerizing or copolymerizing a monomer having an ionic group such as an acid group or an amino group. One charge control agent may be used alone, or two or more charge control agents may be used in combination.

  The blending amount of the charge control agent is not particularly limited, and is appropriately selected from a wide range according to various conditions such as the type and content of other components such as a binder resin and a colorant, and characteristics required for the toner to be manufactured. Although it can be selected, it is preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the binder resin. By including the charge control agent in such a range, it is possible to perform charge amount stability control that prevents changes in the toner charge amount due to environmental fluctuations. If the charge control agent is less than 0.5 part by weight, there is a possibility that sufficient charge stability cannot be imparted to the toner. If the charge control agent exceeds 5 parts by weight, it may be difficult to uniformly disperse the charge control agent in the binder resin.

  In the melt-kneading step, for example, a raw material containing additives such as the binder resin, the colorant, the release agent and the compatibilizing agent, and the charge control agent added when it is necessary to control the charging performance of the toner is used. Then, after dry-mixing with a mixer, the mixture 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, for example, not lower than 80 ° C and not higher than 200 ° C, preferably not lower than 100 ° C and not higher than 150 ° C. The coloring resin is softened to disperse a colorant, a release agent and the like in the binder resin. The raw materials including the binder resin, the colorant, the release agent, and the compatibilizer may be melt-kneaded as they are without being dry mixed. However, the melt kneading after dry mixing as in this embodiment improves the dispersibility in the binder resin of raw materials other than the binder resin such as the colorant and the release agent, and the obtained toner It is preferable because characteristics such as charging performance can be made uniform.

  As a mixer used for dry mixing, for example, 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. Examples include a Henschel type mixing apparatus, Ong mill (trade name, manufactured by Hosokawa Micron Corporation), hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), and Cosmo system (trade name, manufactured by Kawasaki Heavy Industries, Ltd.).

  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.

The softening point of the resin kneaded product thus obtained is, for example, 80 ° C. or higher and 150 ° C. or lower, and preferably 100 ° C. or higher and 130 ° C. or lower. The resin kneaded material has a melt viscosity of 10 ⁵ Pa · s at a temperature at which the mixture of the resin kneaded material and the aqueous medium is heated in the granulation step of step s3 described later (hereinafter also referred to as “granulation temperature”). The following is preferable. Thereby, granulation of the resin kneaded product can be performed more easily. The softening point and the melt viscosity at the granulation temperature of the resin kneaded product can be adjusted, for example, by appropriately selecting the constituent materials of the raw materials and the mixing ratio.

  In the melt-kneading process, when the compatibilizer is contained in the raw material and melt-kneaded together with the binder resin and the release agent, the interfacial tension between the binder resin and the release agent is not included in the raw material. Can be made smaller. As a result, the binder resin and the release agent can be dissolved, and the release agent can be prevented from agglomerating. Therefore, the size is sufficiently smaller than the particle size (for example, 5 to 10 μm) of the toner to be manufactured. The release agent can be uniformly dispersed in the binder resin. In this way, by dispersing the release agent in the binder resin in a sufficiently small state in the melt-kneading step, the release agent can be used even when the resin kneaded product is heated in the granulation step described later. Aggregation of the release agent in the resin kneaded product is prevented more than when a resin kneaded product that aggregates in the resin is used.

[Aqueous medium preparation step]
In the aqueous medium preparation step of step s2, an aqueous medium containing a dispersant and water is prepared. As the dispersant, a water-soluble compound is preferably used.

  When a substance that does not dissolve in water is used as a dispersant, the dispersant exists as a solid in the mixture of the kneaded material and the aqueous medium, so that the dispersant works in the same way as a boiling stone in the granulation process. Micro bubbles are generated on the surface. This bubble becomes an active point and foaming occurs, which may hinder the stirring by the stirring device and, consequently, the crushing of the kneaded product. By using a water-soluble compound as the dispersant, bubbles are prevented from being generated from the dispersant in the granulation step, so that the resin kneaded product can be efficiently granulated.

  Further, it is more preferable to use a water-soluble polymer compound as the dispersant. In the present invention, the water-soluble polymer compound is a water-soluble compound having a weight average molecular weight (Mw) of 1000 or more. By using a water-soluble polymer compound as the dispersing agent, the granulation of the resin kneaded product easily proceeds, so that toner particles having a uniform shape and size can be obtained efficiently. Further, since the dispersant adhering to the toner particles can be removed by a simple operation of washing with water, it is excellent in productivity and industrially advantageous.

  When a water-soluble polymer compound is used as the dispersant, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the water-soluble polymer compound is preferably 4.0 or less. The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is called a molecular weight distribution index and serves as an index of the width of the molecular weight distribution. It means that the smaller the molecular weight distribution index (Mw / Mn), the smaller the molecular weight distribution width and the more uniform the molecular weight.

  When the molecular weight distribution index (Mw / Mn) of the water-soluble polymer compound is 4.0 or less, the molecular weight of each water-soluble polymer contained in the water-soluble polymer compound can be made uniform. Moreover, the length of the main chain of each water-soluble polymer can be made uniform. Further, the number of functional groups possessed by each water-soluble polymer can be made uniform. Accordingly, in the granulation step described later, the resin kneaded material can be dispersed in a uniform size in an aqueous medium containing a water-soluble polymer compound as a dispersant. Can be generated.

  When the molecular weight distribution index (Mw / Mn) of the water-soluble polymer compound exceeds 4.0, the molecular weight and main chain length of each water-soluble polymer contained in the water-soluble polymer compound, and each water-soluble polymer Since at least any one of the number of functional groups of the resin becomes non-uniform, there is a possibility that the resin kneaded material cannot be dispersed in a uniform size in the aqueous medium. As a result, the particle size distribution of the generated toner particles is broadened, and the particle size of the toner particles becomes non-uniform. Therefore, when the toner particles are used as they are, the charge amount of the toner particles becomes non-uniform, the image density decreases, the image This may cause fogging or transferability deterioration. In order to make the charge amount of the toner particles uniform, it is necessary to provide a classification process and narrow the particle size distribution, which complicates the manufacturing process. In addition, the molecular weight distribution of the water-soluble polymer compound is widened, and there is a possibility that the water-soluble polymer compound easily dissolves in water and the water-soluble polymer compound coexist, so that an aqueous medium having a desired solid content concentration can be prepared. It becomes difficult.

  When the molecular weight of each water-soluble polymer contained in the water-soluble polymer compound is equal and single, the molecular weight distribution index (Mw / Mn) is 1.0. Therefore, the molecular weight distribution index (Mw / Mn) of the water-soluble polymer compound is 1.0 or more and 4.0 or less, and is preferably as close to 1.0 as possible.

  The molecular weight distribution index (Mw / Mn) of the water-soluble polymer compound can be reduced to 4.0 or less, for example, by adjusting the type of monomer that is a raw material of the water-soluble polymer compound, the degree of polymerization, and the like. When the water-soluble polymer compound is a copolymer, the molecular weight distribution index (Mw / Mn) can be reduced to 4.0 or less by adjusting the copolymerization ratio.

  The weight average molecular weight (Mw) of the water-soluble polymer compound is preferably 1000 or more and 20000 or less. By setting the weight average molecular weight (Mw) of the water-soluble polymer compound within this range, an increase in the viscosity of the aqueous medium can be suppressed, and the resin kneaded material can be efficiently dispersed in the aqueous medium. Thereby, for example, small toner particles having a volume average particle diameter of 10 μm or less can be easily generated. In addition, since the spread of the particle size distribution of the toner particles can be suppressed, the toner charge amount can be prevented from becoming non-uniform.

  When the weight average molecular weight (Mw) of the water-soluble polymer compound exceeds 20000, the viscosity of the aqueous medium increases, and it may be difficult to mix with the resin kneaded product in the granulation step. In addition, since the shearing force generated by stirring the mixture in the granulation step is applied to the aqueous medium and is difficult to be applied to the resin kneaded product, granulation of the resin kneaded product is inhibited, and the resin kneaded material is dispersed in the aqueous medium. It becomes difficult. As a result, the particle diameter of the toner particles tends to be large, and it may be difficult to produce small toner particles having a volume average particle diameter of 10 μm or less. Even if toner particles having a desired average particle size can be generated, the particle size distribution of the toner particles tends to be wide, and the charge amount of the toner may be nonuniform.

  When the weight average molecular weight (Mw) of the water-soluble polymer compound is less than 1000, there is a high possibility that the water-soluble polymer compound contains an oligomer or an unreacted monomer, and the water-soluble polymer compound is an oligomer or monomer. Therefore, the function as a dispersant cannot be exhibited in the granulation step, and the resin kneaded material may not be dispersed in the aqueous medium.

The weight average molecular weight (Mw) and number average molecular weight (Mn) of the water-soluble polymer compound can be adjusted by, for example, the type of monomer that is a raw material of the water-soluble polymer compound, the degree of polymerization, and the like. Moreover, when a water-soluble high molecular compound consists of a copolymer, it can adjust also by copolymerization ratio etc. Here, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the water-soluble polymer compound are determined by gel permeation chromatography (Gel Permeation).
It is a value in terms of polystyrene measured by Chromatography (abbreviation GPC). Hereinafter, the weight average molecular weight may be simply expressed as “Mw”. The number average molecular weight may be simply expressed as “Mn”.

  The water-soluble polymer compound is preferably an ionic water-soluble polymer compound having an ionic group. Among water-soluble polymer compounds, nonionic water-soluble polymer compounds having no ionic group, such as polyvinyl alcohol and polyvinyl pyrrolidone, are inferior in solubility in water compared to ionic water-soluble polymer compounds. Therefore, the toner particles may be deposited on the surface of the toner particles in the cooling step described later. Once the nonionic water-soluble polymer compound is deposited on the surface of the toner particles, it is difficult to remove the nonionic water-soluble polymer compound even by washing in the washing step described later. There is a possibility that a nonionic water-soluble polymer compound may remain on the surface. In addition, when a nonionic water-soluble polymer compound is used, it is difficult to adjust the solid content concentration of the dispersant in the aqueous medium, and in particular, it is possible to adjust a high concentration aqueous medium in which the solid content concentration exceeds 10% by weight. Therefore, it becomes difficult to uniformly disperse the resin kneaded material in the aqueous medium. By using an ionic water-soluble polymer compound, the solubility of the water-soluble polymer compound in water can be improved, so that the concentration can be easily adjusted. In addition, since the ionic water-soluble polymer compound is easily removed by washing, the use of the ionic water-soluble polymer compound further ensures that the water-soluble polymer compound remains on the toner particle surface, which is a toner particle. Can be prevented.

  Examples of the ionic water-soluble polymer compound include an anionic water-soluble polymer compound having an anionic group and a cationic water-soluble polymer compound having a cationic group. Is preferred. By using an anionic water-soluble polymer compound, the dispersibility of the resin kneaded product in the mixture in the granulation step can be improved, and the particle size of the toner particles can be made more uniform. Here, the “anionic group” is a group that dissociates in water and releases a cation. The “cationic group” is a group that dissociates in water and releases an anion.

  Examples of the anionic water-soluble polymer compound include homopolymers and copolymers of vinyl carboxylic acid, and salts thereof. Here, the “vinyl carboxylic acid” is a compound having a vinyl group and a carboxyl group. Examples of the vinyl carboxylic acid include acrylic acids such as acrylic acid and methacrylic acid, and maleic acid.

  Examples of the homopolymer of vinyl carboxylic acid (hereinafter also referred to as “polyvinyl carboxylic acid”) include polyacrylic acids such as polyacrylic acid and polymethacrylic acid. Examples of the salt of polyvinyl carboxylic acid include ammonium salts of polyvinyl carboxylic acid such as ammonium polyacrylate and ammonium polymethacrylate, and alkali metal salts of polyvinyl carboxylic acid such as sodium polyacrylate and sodium polymethacrylate.

  Examples of the vinyl carboxylic acid copolymer (hereinafter also referred to as “vinyl carboxylic acid copolymer”) include a copolymer of vinyl carboxylic acid and a vinyl monomer. Examples of the vinyl carboxylic acid include acrylic acids such as the aforementioned acrylic acid and methacrylic acid, and maleic acid. Examples of the vinyl monomer copolymerized with vinyl carboxylic acid include styrene derivatives such as styrene and α-alkylstyrene such as α-methylstyrene. One vinyl monomer may be used alone, or two or more vinyl monomers may be used in combination.

  Specific examples of the copolymer of vinyl carboxylic acid and vinyl monomer include styrene-acrylic acid copolymer which is a copolymer of styrene and acrylic acid, and copolymer of styrene, α-methylstyrene and acrylic acid. Examples thereof include styrene-acrylic acid copolymers such as styrene-α-methylstyrene-acrylic acid copolymers and styrene-vinylcarboxylic acid copolymers such as styrene-maleic acid copolymers.

  Examples of vinyl carboxylic acid copolymer salts include styrene-acrylic acid copolymer ammonium salts and styrene-acrylic acid copolymer ammonium salts such as styrene-α-methylstyrene-acrylic acid copolymer ammonium salts. Vinyl carboxylic acid copolymer ammonium salts, sodium styrene-acrylic acid copolymer sodium, styrene-acrylic acid copolymer sodium salts such as sodium styrene-α-methylstyrene-acrylic acid copolymer sodium, vinyl Examples include alkali metal salts of carboxylic acid copolymers.

  Polyvinylcarboxylic acid can be produced, for example, by polymerizing vinylcarboxylic acid in the presence of a radical initiator by a solution polymerization method, a suspension polymerization method or an emulsion polymerization method. The vinyl carboxylic acid copolymer is prepared by, for example, subjecting one or more vinyl carboxylic acids and one or more vinyl monomers to a solution polymerization method or suspension in the presence of a radical initiator. It can be produced by polymerizing by a polymerization method or an emulsion polymerization method. The molecular weight distribution index (Mw / Mn) of the anionic water-soluble polymer compound is 4.0 or less by adjusting the type and degree of polymerization of the raw material monomer, and the copolymerization ratio in the case of the copolymer. Can be.

As the anionic water-soluble polymer compound, a commercially available product can be used. Examples of commercially available anionic water-soluble polymer compounds include Jonkrill 61J (ammonium salt of styrene-α-methylstyrene-acrylic acid copolymer, Mw = 13000, Mn = 3700, Mw / Mn = manufactured by Johnson Polymer Co., Ltd. 3.5),
Joncryl 52 (ammonium salt of styrene-acrylic acid copolymer, Mw = 1700, Mn = 900, Mw / Mn = 1.9),
Joncryl 57 (ammonium salt of styrene-acrylic acid copolymer, Mw = 4200, Mn = 1800, Mw / Mn = 2.3) and Joncryl 60 (ammonium salt of styrene-acrylic acid copolymer, Mw = 9000) , Mn = 3700, Mw / Mn = 2.4), etc., and A-30SL manufactured by Toagosei Co., Ltd. (ammonium salt of polyacrylic acid, Mw = 6000, Mn = 3000, Mw / Mn = 2.0), etc. Is mentioned.

  In the polyvinyl carboxylic acid and the vinyl carboxylic acid copolymer, the carboxyl group derived from the vinyl carboxylic acid becomes an anionic group. In the polyvinyl carboxylate and vinyl carboxylic acid copolymer salt, a group obtained by substituting a hydrogen ion contained in a carboxyl group derived from vinyl carboxylic acid with a cation group such as a metal ion or an ammonium ion is an anionic group.

  Among the aforementioned anionic water-soluble polymer compounds, polyacrylic acid salts and styrene-acrylic acid copolymer salts are preferred, and polyacrylic acid ammonium salts and styrene-acrylic acid copolymer ammonium salts are preferred. Further preferred. By using at least one of a salt of polyacrylic acid and a salt of styrene-acrylic acid copolymer, the resin kneaded material can be more uniformly dispersed in the aqueous medium. A toner having a diameter can be obtained more reliably. One type of water-soluble polymer compound may be used alone, or two or more types may be used in combination.

  The concentration of the water-soluble polymer compound in the aqueous medium is not particularly limited, and depends on the types and contents of the binder resin, the colorant, the release agent, the compatibilizer and the additive contained in the resin kneaded product. Although it can be appropriately selected from a wide range, in view of the ease of mixing operation of the resin kneaded product and the aqueous medium, the dispersion stability of the produced toner particles, etc., 5 wt. % Or more and 40% by weight or less is preferable. When the concentration of the water-soluble polymer compound is less than 5% by weight, a large amount of aqueous medium is required to realize a suitable use ratio of the water-soluble polymer compound to the resin kneaded product in the granulation step described later. The mixing operation of the resin kneaded product and the aqueous medium may be complicated. If the concentration of the water-soluble polymer compound exceeds 40% by weight, the viscosity of the aqueous medium becomes high, which may make it difficult to mix with the resin kneaded product in the granulation step. Further, the granulation of the resin kneaded product is hindered, and the resin kneaded product cannot be uniformly dispersed in the aqueous medium, and the particle size of the produced toner particles may be nonuniform.

  The dispersant is not limited to the use of a water-soluble polymer compound, and for example, a sparingly water-soluble and acid-decomposable inorganic compound (hereinafter also referred to as “hardly water-soluble inorganic compound”) can be used. When a poorly water-soluble inorganic compound is used as the dispersant, fine bubbles may be generated on the surface of the dispersant in the granulation step as described above. Since the poorly water-soluble inorganic compound uniformly adheres to the surface, the generation of coarse particles due to the adhesion of the toner particles is prevented. This makes it possible to obtain a toner with uniform particle shape and size and no variation in charging performance. However, when a poorly water-soluble inorganic compound is used as the dispersant, a dispersant removing step is required to remove the poorly water-soluble inorganic compound adhering to the surface of the toner particles. This dispersing agent removal process is performed between the cooling process of step s4 and the washing process of step s5.

  As the hardly water-soluble inorganic compound, an inorganic compound having low water solubility and being decomposed by an acid can be used. The solubility of the hardly water-soluble inorganic compound in water is not particularly limited, but the solubility in 100 g of water at a temperature of 25 ° C. is preferably 5 g or less, more preferably 1 g or less.

  Examples of such poorly water-soluble inorganic compounds include calcium carbonate salts and calcium phosphate salts. In view of making the particle size distribution of the resulting toner as narrow as possible and making the shape uniform, calcium phosphate salts are preferable. Examples of the calcium phosphate salt include calcium hydrogen phosphate, calcium dihydrogen phosphate, calcium trihydrogen phosphate, and hydroxyapatite. Among these, hydroxyapatite is preferable in consideration of a low solubility in water, a high decomposability (solubility) in acid, a fine crystal size, and the like. As the poorly water-soluble inorganic compound, one kind may be used alone, or two or more kinds may be used in combination.

  The concentration of the poorly water-soluble inorganic compound in the aqueous medium is determined by considering the dispersibility of the poorly water-soluble inorganic compound in the aqueous medium and the operability in the granulation process of mixing the aqueous medium and the resin kneaded material. In an aqueous medium at 25 ° C., the content is preferably 3% by weight or more and 20% by weight or less, and more preferably 5% by weight or more and 15% by weight or less. If the concentration of the hardly water-soluble inorganic compound is less than 3% by weight, a large amount of aqueous medium may be required to realize a suitable use ratio of the hardly water-soluble inorganic compound to the resin kneaded product in the granulation step described later. There is. When the concentration of the hardly water-soluble inorganic compound exceeds 20% by weight, the dispersibility of the hardly water-soluble inorganic compound in the aqueous medium may be lowered.

  The aqueous medium can be prepared, for example, by dissolving or dispersing an appropriate amount of the aforementioned dispersant in water. As water, it is preferable to use water having an electrical conductivity of 20 μS / cm or less. Water whose conductivity is within the above range can be prepared by, for example, an activated carbon method, an ion exchange method, a distillation method, or a reverse osmosis method. Moreover, you may prepare the water whose electrical conductivity is in the said range by combining 2 or more types among these methods. Moreover, it can also prepare using a commercially available pure water manufacturing apparatus, for example, Minipure TW-300RU (trade name) manufactured by Nomura Micro Science Co., Ltd.

[Granulation process]
In the granulation step of step s3, the binder resin of the resin kneaded product obtained by the melt kneading step is softened in an aqueous medium containing a dispersant and water, and the resin kneaded material is dispersed in the aqueous medium to form particles. To obtain toner particles. Here, the toner particles are particles obtained by granulating a resin kneaded material containing at least a binder resin, a colorant, a release agent, and a compatibilizing agent. Toner is a surface modification to toner particles. When an external additive such as a quality additive is not externally added, it means toner particles themselves, and when an external additive such as a surface modifier is externally added to toner particles, the toner particles and external additives are combined. It is a mixture containing.

  In the granulation step, the mixture of the aqueous medium and the resin kneaded product is heated in order to soften the binder resin of the resin kneaded product obtained by the melt kneading step in the aqueous medium. The heating temperature (granulation temperature) of the mixture of the aqueous medium and the resin kneaded product in the granulation step is not particularly limited, and the type of the binder resin contained in the resin kneaded product and its characteristics, such as the softening point, are final. Although it can be appropriately selected from a wide range according to the particle size of the toner particles to be obtained, the temperature is preferably higher than the softening point of the binder resin contained in the resin kneaded material and lower than the thermal decomposition temperature. By performing the granulation step at such a temperature, the binder resin can be softened without being thermally decomposed, so that the granulation can be performed efficiently. In the granulation step, it is not always necessary to heat the mixture of the aqueous medium and the resin kneaded material. For example, when using an aqueous medium and a resin kneaded product that have been preheated to a temperature that is higher than the softening point of the binder resin and lower than the thermal decomposition temperature, the temperature of the mixture during granulation is maintained in the above temperature range. If this is the case, heating is not necessary.

  Further, the mixing of the aqueous medium and the resin kneaded material is performed while applying a shearing force with a stirring device or the like. The stirring speed of the aqueous medium and the resin kneaded product is not particularly limited, and the stirring speed depends on the type and content of the binder resin, the colorant, the release agent, the compatibilizing agent and the additive in the resin kneaded product. It is only necessary to appropriately select a value that allows easy operation and results in toner particles having a desired particle size, particle size distribution, and shape. The stirring time of the aqueous medium and the resin kneaded product is not particularly limited, and the types and contents of the binder resin, the colorant, the release agent, the compatibilizing agent and the additive in the resin kneaded product, Depending on various conditions such as the type and concentration of the dispersant and the heating temperature of the mixture, it can be appropriately selected from a wide range, for example, from 10 minutes to 20 minutes.

  The mixture is preferably heated while the inside of the mixing container in which the mixture of the aqueous medium and the resin kneaded material is accommodated is pressurized. Thereby, since the boiling point of the water contained in the mixture can be raised, the mixture can be heated to 100 ° C. or higher without boiling the water in the mixture. Therefore, it is possible to prevent a decrease in shearing force due to the generation of bubbles, and it is possible to more efficiently granulate the resin kneaded product.

  When the mixture is heated while the inside of the mixing container is pressurized, the pressure of the gas in the mixing container (hereinafter referred to as “pressure in the mixing container” for convenience of explanation) is not particularly limited, Depending on various conditions such as binder resin, colorant, mold release agent, compatibilizer and additive, type and content of dispersant in aqueous medium, heating temperature of mixture, etc. What is necessary is just to select suitably the pressure which can be implemented easily and can obtain the toner particle which has a desired particle size and shape. The pressure in the mixing container is, for example, 0.1 MPa (about 1 atm) or more and 1 MPa (about 10 atm) or less. Here, the “pressurized state” is a state where the pressure in the mixing container is higher than the atmospheric pressure (1 atm).

  However, if the pressure in the mixing container becomes too high, bubbles generated in the mixture may not be lost, but may be refined by pressure and contained in the system, which may hinder granulation of the resin kneaded product. The pressure in the mixing vessel is preferably a minimum pressure that can suppress boiling of water in the mixture at a desired heating temperature. Therefore, the pressure in the mixing vessel is appropriately selected particularly in consideration of the heating temperature of the mixture. For example, when the heating temperature of the mixture is 150 ° C., the pressure in the mixing container is about 0.5 MPa (about 5 atm).

  As the resin kneaded material to be mixed with the aqueous medium, a material obtained by melting and kneading raw materials including a binder resin, a colorant, a release agent, a compatibilizing agent, and an additive may be used as it is. The obtained solidified product may be used as it is or after being heated again to return to a molten state.

  The mixing ratio of the aqueous medium and the resin kneaded material is not particularly limited, and is appropriately selected from a wide range according to various conditions such as the content of the binder resin in the resin kneaded material and the type and content of the dispersant in the aqueous medium. Although it can be selected, from the viewpoint of efficiently carrying out the mixing operation of the aqueous medium and the resin kneaded product, the separation operation of the toner particles from the aqueous medium, etc. The aqueous medium is preferably used in an amount of 100 parts by weight to 500 parts by weight with respect to parts. Moreover, when using a poorly water-soluble inorganic compound as a dispersing agent, it is preferable to use 100 to 1000 weight part of aqueous media with respect to 100 weight part of kneaded materials.

  Mixing of the aqueous medium and the resin kneaded material is performed using, for example, an emulsifier or a disperser. As an emulsifier and a disperser (hereinafter, the emulsifier and the disperser are collectively referred to as an emulsifier), an aqueous medium and a resin kneaded material can be received batchwise or continuously, and heating means or heating means and It has a pressurizing means, and the aqueous medium and the resin kneaded material are mixed under heating or heating and pressurization to form toner particles in the aqueous medium, and the toner particles can be discharged batchwise or continuously. An apparatus is preferred. The emulsifier needs to have a stirring means and be capable of mixing the aqueous medium and the resin kneaded material with stirring. In the emulsifier, it is preferable that the mixing container for mixing the aqueous medium and the resin kneaded material has a temperature adjusting means. The mixing vessel preferably has pressure resistance, and more preferably has pressure resistance and is provided with a pressure regulating valve and the like. If such a mixing container is used, the temperature of the mixture in the container can be kept almost constant, and the pressure in the mixing container is also kept constant in consideration of the softening point of the binder resin and the vapor pressure of the aqueous medium. Be controlled. In addition, when mixing the aqueous medium and the resin kneaded product at a heating temperature of 100 ° C. or higher, the emulsifier is equipped with a mechanical seal and the mixing container can be sealed because it is used in a pressurized state. Is preferred.

  Such emulsifiers are commercially available. Examples of commercially available emulsifiers include Ultra Tarrax (trade name, manufactured by IKA Japan Co., Ltd.), Polytron Homogenizer (trade name, manufactured by KINEMATICA), and T.C. K. Batch type emulsifiers such as auto homomixer (trade name, manufactured by Tokushu Kika Kogyo Co., Ltd. (currently Primemix Co., Ltd.)), Ebara Milder (trade name, manufactured by Ebara Corporation), T. K. Pipeline homomixer, T.W. K. Homomic line flow, T.W. K. Fill mix (all are trade names, manufactured by Koki Kogyo Co., Ltd.), colloid mill (trade names, manufactured by Shinko Pantech Co., Ltd.), slasher, trigonal wet pulverizer (all are trade names, Mitsui Miike Chemical Machinery Co., Ltd.) Co., Ltd.), Cavitron (trade name, manufactured by Eurotech Co., Ltd.), and fine flow mills (manufactured by Taiheiyo Kiko Co., Ltd.) and other continuous emulsifiers, Claremix (trade name, manufactured by M Technique Co., Ltd.), Phil Mix (trade name, manufactured by Tokushu Kika Kogyo Co., Ltd.)

  By heating and stirring the mixture of the aqueous medium and the resin kneaded material as described above, toner particles containing a binder resin, a colorant, a release agent, and a compatibilizing agent are generated in the aqueous medium. . In such a granulation step, the mixture of the aqueous medium and the resin kneaded product is heated so that the release agent tends to aggregate. However, the toner particles are contained in the binder resin in the above-described melt kneading step. Since it is granulated from a resin kneaded product excellent in dispersibility of the release agent, it is possible to prevent the release agent from agglomerating in the granulating step as compared with the case of using a resin kneaded product in which the release agent is agglomerated. . Moreover, since the resin kneaded material contains a compatibilizing agent, the release agent can be prevented from agglomerating even in the granulation step. Therefore, the dispersibility of the release agent in the toner particles is improved, and the release agent can be released less than when the release agent aggregates and is present in the resin kneaded product. The content of the release agent in the particles can be made substantially equal to the content of the release agent in the resin kneaded product.

[Cooling process]
In the cooling step of step s4, the mixture containing the granulated toner particles (hereinafter also referred to as an aqueous slurry) is cooled. The cooling of the aqueous slurry may be performed by forced cooling in which heating is stopped after the toner particles are generated in the granulation process in step s3 and forcibly cooled using a refrigerant, or natural cooling in which the toner is allowed to cool as it is. preferable.

  In the granulation step, the mixture of the aqueous medium and the resin kneaded product is heated and granulated by softening and dispersing the resin kneaded product, so that the toner particles immediately after being produced are in a softened state and are adhesive. Have In this state, the toner particles adhere to each other and are easily coarsened. However, when a water-soluble polymer compound having a molecular weight distribution index (Mw / Mn) of 4.0 or less is used as the dispersant, the toner particles are highly water-soluble. It is stabilized by molecular compounds and is uniformly dispersed in an aqueous medium. In addition, when a poorly water-soluble inorganic compound is used as the dispersant, the poorly water-soluble inorganic compound uniformly adheres to the surface of the toner particles, and in the state in which coarse particles are prevented from being generated due to adhesion between the toner particles. Are evenly distributed. Therefore, in the cooling step, the toner particles are not coarsened, and the toner particles can be cooled while maintaining the shape and size while being uniformly dispersed in the aqueous medium. Thereby, for example, toner particles having a volume average particle size of 10 μm or less, preferably 5 μm or more and 10 μm or less, and a narrow particle size distribution and a uniform particle size can be obtained.

  The mixture is preferably cooled with stirring. When the mixture is cooled without stirring, when the temperature of the mixture is equal to or higher than the softening point of the binder resin contained in the toner particles, and the dispersant is a water-soluble polymer compound, the dispersion with the water-soluble polymer compound is performed. The stability effect is not sufficiently exhibited, and the toner particles may be fused to each other. Therefore, it is preferable to continue stirring the mixture also in the cooling step.

  Moreover, when granulation of the resin kneaded material is performed under pressure with the heating temperature of the mixture being 100 ° C. or higher, it is preferable to continue the pressure in the cooling step. When the temperature of the mixture is 100 ° C. or higher, if the pressure is stopped and the pressure in the mixing container is returned to atmospheric pressure, the water in the mixture boils and many bubbles are generated, making subsequent processing difficult. become. The pressure in the mixing container is preferably returned to atmospheric pressure when the temperature of the mixture in the mixing container becomes 50 ° C. or lower. After the mixture in the mixing container is cooled to room temperature (about 25 ° C.), the pressure in the mixing container is increased to atmospheric pressure. More preferably, it is returned.

  After performing the cooling process, a cleaning process for cleaning the toner particles is performed. When a poorly water-soluble inorganic compound is used as the dispersant, a dispersant removing process for removing the poorly water-soluble inorganic compound adhering to the surface of the toner particles is performed. Performed before the cleaning process.

  In the dispersing agent removal step, the pH of the aqueous medium contained in the mixture after cooling is adjusted to acidic, preferably 1.0 to 3.0, and the hardly water-soluble inorganic that is a hardly water-soluble and acid-decomposable inorganic compound The compound is decomposed and removed from the toner particle surface.

  An inorganic acid is used to adjust the pH of the aqueous medium. Examples of the inorganic acid include water-soluble inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid. By using such an inorganic acid, the poorly water-soluble inorganic compound on the surface of the toner particles is dissolved in the aqueous medium after pH adjustment and is removed from the surface of the toner particles.

[Washing process]
In the washing process of step s5, the toner particles contained in the cooled aqueous medium are washed. The toner particles are washed to remove impurities derived from the dispersant and the dispersant. If the dispersant and the impurities remain in the toner particles, the charging performance of the obtained toner particles may become unstable. Moreover, there exists a possibility that charging property may fall under the influence of the water | moisture content in air.

  The toner particles can be washed, for example, by adding water to the mixture, stirring and washing. The toner particles are washed with water repeatedly using a conductivity meter until the conductivity of the supernatant liquid separated from the mixture by centrifugation or the like becomes 100 μS / cm or less, preferably 10 μS / cm or less. As a result, it is possible to more reliably prevent the dispersant and impurities from remaining and to make the charging performance of the toner particles more uniform.

  The water used for washing is preferably water having a conductivity of 20 μS / cm or less. Such water can be prepared, for example, by an activated carbon method, an ion exchange method, a distillation method, a reverse osmosis method, or the like. Moreover, you may prepare water combining 2 or more types among these methods. The toner particles may be washed with water either batchwise or continuously. The temperature of the washing water is not particularly limited, but is preferably 10 ° C or higher and 80 ° C or lower.

[Separation process]
In the separation step of step s6, the toner particles are separated from the mixture containing the washed toner particles and collected. Separation of the toner particles from the aqueous medium can be performed, for example, by filtration, suction filtration, centrifugation, or the like.

  When the washing process of step s5 is performed after the separation process of step s6, for example, the toner particles can be washed by washing the separated toner particles with water. The toner particles are washed with water using an electric conductivity meter or the like until the conductivity of the washing water after washing the toner particles becomes 100 μS / cm or less, preferably 10 μS / cm or less. As a result, the residue of the dispersant and impurities can be prevented more reliably, and the charging performance of the toner particles can be made more uniform.

[Drying process]
In the drying step of step s7, the washed toner particles are dried. The toner particles, which are toner particles, can be dried by a freeze drying method, an airflow drying method, or the like. When the drying process of step s7 is performed, the production of toner particles is finished in step s8.

  The toner particles obtained in this manner can be used as toner as it is. Further, the toner particles can be surface modified by externally adding an external additive such as a surface modifier to the toner particles. Examples of the surface modifier include metal oxide particles such as silica and titanium oxide. Further, it is also possible to use a metal oxide particle such as silica or titanium oxide that has been subjected to a surface modification treatment such as a hydrophobic treatment with a silane coupling agent or the like. The ratio of the external additive used with respect to the toner particles is not particularly limited, but is preferably 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the toner particles, and is 1 part by weight or more and 5 parts by weight or less. More preferably.

  As described above, a toner composed of toner particles or a mixture containing toner particles and an external additive is obtained. In the present embodiment, in the melt-kneading step, the compatibilizing agent for compatibilizing the binder resin and the release agent is melt-kneaded together with the binder resin and the release agent, thereby preventing the release agent from agglomerating. The release agent can be dispersed in the binder resin with a size smaller than the particle size of the toner to be obtained.

  Further, in the granulation step, toner particles are generated by dispersing the resin kneaded product obtained in the melt-kneading step in an aqueous medium. When toner particles are generated from a resin kneaded product containing a release agent, the release agent melts by heating in the granulation process, and the release agent present near the surface of the resin kneaded product is detached from the resin kneaded product. There is a case. Here, when the release agent is agglomerated and the dispersibility of the release agent in the resin kneaded product is poor, the amount of the release agent to be released is released from the resin kneaded product with excellent release agent dispersibility. The amount of the release agent in the toner particles is lower than the content of the release agent in the resin kneaded product.

  In this embodiment, since the toner particles are generated from the resin kneaded material having excellent dispersibility in the binder resin as described above, the release agent existing near the surface of the resin kneaded material is detached. Even so, the amount is very small compared to the amount of the release agent in the resin kneaded product. Therefore, the content of the release agent in the toner particles can be prevented from being lower than the content of the release agent in the resin kneaded product. As a result, it is possible to manufacture toner particles having a suitable content of the release agent by including the release agent in the raw material at a suitable content, so that high temperature offset can be prevented, that is, high temperature offset. The temperature at which the phenomenon occurs is further increased, and a toner having a wide non-offset region can be obtained.

  Furthermore, in the granulation step of the present embodiment, granulation is performed by dispersing the resin kneaded material in an aqueous medium without mechanically crushing the solidified product of the resin kneaded material, so that the shape is close to a sphere and is fluid. An excellent toner can be obtained.

  In addition, since the resin kneaded product is not dissolved with an organic solvent, but granulation is performed using an aqueous medium, the organic solvent does not remain in the toner particles, and the charging performance of the toner particles can be produced at different occasions. The charging performance of the granulated toner particles can be made substantially equal, and a toner having desired characteristics can be manufactured with good reproducibility. In addition, since it is not necessary to use an organic solvent that has a large environmental impact in the production of toner, a processing facility for appropriately treating the organic solvent is not required.

  In a toner production method that does not use a compatibilizer, for example, when a polyester resin that is suitably used for the production of a color toner is used as a binder resin, a release agent that has poor compatibility with polyester resins such as olefin wax and paraffin wax. If selected, the release agent cannot be dispersed in the polyester resin depending on the granulation conditions, and the content of the release agent contained in the toner is low, so high temperature offset cannot be prevented. There is a fear. On the other hand, in the toner production method of the present invention using a compatibilizer, the release agent can be dispersed in the binder resin even if the compatibility between the binder resin and the release agent is poor. Preferred ones can be selected from the binder resin and the release agent, and the offset resistance is not lowered, so that it is easy to produce a toner having desired characteristics.

  The toner obtained by the toner manufacturing method according to the present embodiment is used for development of an electrostatic charge image in image formation by electrophotography, electrostatic recording method, etc., development of a magnetic latent image in image formation by magnetic recording method, etc. be able to. The toner obtained by the method for producing a toner of the present invention has a narrow particle size distribution, uniform charging performance, a suitable release agent content, and excellent offset resistance.

  Accordingly, when the toner obtained by the toner production method of the present invention is used as an electrostatic image developing toner used for developing an electrostatic image, the toner particle charging performance is constant, so that the image density is lowered and transferred. The deterioration of the property can be suppressed, and the image fog can be prevented. In addition, since it has excellent offset resistance, a high-quality image that does not cause image defects such as image fogging caused by retransfer of the toner adhering to the heating roller to the recording medium and white spots caused by toner adhering to the heating roller can be obtained. Can be formed. The toner obtained by the toner production method of the present invention can be used as a one-component developer or a two-component developer.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following, “parts” and “%” mean “parts by weight” and “% by weight”, respectively, unless otherwise specified.

[Preparation of water]
In the following Examples and Comparative Examples, water having an electrical conductivity of 0.5 μS / cm was used as water for preparing an aqueous medium and water for cleaning toner particles. This washing water was prepared from tap water using an ultrapure water production apparatus (trade name: Minipure TW-300RU, manufactured by Nomura Micro Science Co., Ltd.). The electrical conductivity of water was measured using Lacom Tester EC-PHCON10 (trade name, manufactured by Seiei Iuchi (currently As One Co., Ltd.)).

[Volume average particle size and coefficient of variation]
The volume average particle size of the toner particles (toner particles) was calculated from the results of measurement using Coulter Multisizer II (trade name, manufactured by Coulter, Inc. (currently Beckman Coulter, Inc.). The number of measured particles was 50,000 counts, and the aperture diameter was 100 μm. The coefficient of variation was calculated from the following formula (1) based on the volume average particle diameter obtained from the measured particle diameter and its standard deviation.
Coefficient of variation = standard deviation / volume average particle diameter (1)

[Weight average molecular weight and number average molecular weight of binder resin and water-soluble polymer compound]
The weight average molecular weight Mw and number average molecular weight Mn of the binder resin and the water-soluble polymer compound were measured as follows. A column set at a temperature of 40 ° C. was used in a GPC apparatus (trade name: HLC-8220 GPC, manufactured by Tosoh Corporation), and the injection amount of the sample solution was measured as 100 mL. As the sample solution, a solution obtained by drying a 0.25 wt% (solid content concentration) tetrahydrofuran solution of a sample obtained by drying the binder resin or the water-soluble polymer compound overnight was used. The molecular weight calibration curve was prepared using standard polystyrene (monodisperse polystyrene).

[Softening point of binder resin]
The softening point of the binder resin was measured as follows. 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.

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

[Melting point of release agent]
The melting point of the release agent was measured as follows. 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.

[Residual rate of release agent]
As a residual ratio of the release agent, a ratio of the content of the release agent in the toner particles to the content of the release agent in the raw material was calculated. The content of the release agent in the toner particles is measured by using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.), using the toner as a measurement sample, that is, the endothermic peak area attributed to the release agent, The endothermic amount of the release agent in the toner was determined, and the content was determined by comparing the content of the release agent with the amount of toner as a measurement sample.

Example 1
[Melting and kneading process]
400 parts of polyoxypropylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 380 parts of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane and terephthalic acid A polyester resin (glass transition point (Tg) 62 ° C., softening point 130 ° C.) synthesized using 330 parts as a raw material monomer and 3 parts of dibutyltin oxide as a catalyst, and copper phthalocyanine (C.I. Pigment) as a colorant Blue 15: 3) was added and melt kneaded for 40 minutes in a kneader set at a temperature of 140 ° C. to prepare a master batch having a colorant concentration of 40% by weight. Here, polyoxypropylene (2.0) -2,2-bis (4-hydroxyphenyl) propane refers to propylene oxide with respect to 1.0 mol of 2,2-bis (4-hydroxyphenyl) propane. It is a compound with an average of 2.0 moles added. Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane is an average of 2 ethylene oxides per 1.0 mol of 2,2-bis (4-hydroxyphenyl) propane. This is a compound added with 0.0 mol.

  Next, 82.5 parts of the same polyester resin (glass transition point (Tg) 62 ° C., softening point 130 ° C.) used for the preparation of the master batch, the master batch prepared as described above (colorant concentration 40% by weight) ) 12.5 parts, polyethylene wax (trade name: PW-655N, manufactured by Toyo Petrolite Co., Ltd., melting point 100 ° C.) 5 parts, α-olefin-maleic anhydride copolymer and anhydrous as compatibilizer 3 parts of copolymer with maleic acid monoester (trade name: Ceramer 1608, manufactured by Toyo Petrolite Co., Ltd.) and 2 parts of charge control agent (trade name: TN105, Hodogaya Chemical Co., Ltd.) are mixed with a Henschel mixer. The raw material was obtained by mixing and dispersing for a minute. The obtained raw material was melt-kneaded and dispersed using a twin-screw extruder (trade name: PCM-30, manufactured by Ikegai Co., Ltd.) to prepare a resin kneaded product. The operating conditions of the twin screw extruder were a cylinder set temperature of 110 ° C., a barrel rotation speed of 300 revolutions per minute (300 rpm), and a raw material supply speed of 20 kg / hour.

[Aqueous medium preparation step]
As a dispersant, 100 parts (solid content) of water-soluble polymer compound styrene-α-methylstyrene-acrylic acid copolymer ammonium salt (trade name: John Crill 61J, manufactured by Johnson Polymer Co., Ltd.) and 900 parts of water And an aqueous medium having a dispersant concentration of 10% by weight was prepared.

[Granulation process]
In a metal mixing vessel equipped with a pressure regulating valve, heating means and rotor-stator stirring means (diameter 30 mm), 100 parts of the resin kneaded material prepared as described above and 550 parts of an aqueous medium (dispersant concentration 10% by weight). The mixture was stirred and mixed for 10 minutes with a rotor-stator stirring means while heating so that the temperature of the mixture in the mixing container became 120 ° C. under a pressure of 5 atm (5 atm), thereby generating toner particles. The rotational speed of the rotor of the rotor stator type stirring means at this time was 15,000 revolutions per minute (15000 rpm).

[Cooling process]
After producing the toner particles as described above, heating was stopped, and the mixture containing the produced toner particles was cooled to 20 ° C. while stirring the mixture. The rotational speed of the rotor of the rotor stator type stirring means at this time was 15,000 revolutions per minute (15000 rpm).

[Washing process]
Next, water having a conductivity of 0.5 μS / cm (temperature of 20 ° C.) was added to the mixture to clean the toner particles. To clean the toner particles, water (conductivity 0.5 μS / cm) is added to the mixture, and the solid content is adjusted to 10% by the amount of water added. The rotation speed was 300 revolutions per minute (300 rpm), and stirring was performed for 30 minutes. This washing operation was repeated until the electrical conductivity of the supernatant liquid separated from the stirred mixture by centrifugation was 10 μS / cm or less.

[Separation process]
The solid content containing toner particles was separated from the washed mixture by centrifugation.

[Drying process]
The collected solid content was lyophilized to obtain toner particles. The obtained toner particles had a volume average particle diameter of 6.5 μm and a coefficient of variation of 31.

[External addition process]
To 100 parts of the obtained toner particles, 0.7 part of silica particles having an average primary particle size of 20 nm hydrophobized with a silane coupling agent and 1 part of titanium oxide were mixed to obtain a toner.

(Example 2)
Example 1 with the exception that an α-olefin-maleic anhydride copolymer and a maleic anhydride monoester copolymer (trade name: Ceramer 1251, manufactured by Toyo Petrolite Co., Ltd.) were used as the compatibilizing agent. Similarly, the toner of Example 2 was produced. The toner particles of Example 2 have a volume average particle size of 6.4 μm and a coefficient of variation of 32.

(Example 3)
A toner of Example 3 was prepared in the same manner as in Example 1 except that polyethylene wax (trade name: PW500, manufactured by Toyo Petrolite Co., Ltd., melting point 88 ° C.) was used as a release agent. The toner particles of Example 3 had a volume average particle size of 6.8 μm and a coefficient of variation of 33.

(Comparative Example 1)
A toner of Comparative Example 1 was produced in the same manner as in Example 1 except that the raw material did not contain a compatibilizer. The toner particles of Comparative Example 1 had a volume average particle size of 6.4 μm and a coefficient of variation of 34.

(Comparative Example 2)
A toner of Comparative Example 2 was produced in the same manner as in Example 3 except that the raw material did not contain a compatibilizer. The volume average particle diameter of the toner particles of Comparative Example 2 was 6.2 μm, and the coefficient of variation was 31.

(Characteristic evaluation)
In each of the toners obtained in Examples 1 to 3 and Comparative Examples 1 and 2, as a carrier, a ferrite core carrier having a volume average particle size of 60 μm was adjusted and mixed so that the toner concentration would be 4% by weight. A two-component developer having a toner concentration of 4% by weight was prepared. An image for evaluation was formed as follows using the obtained two-component developer, and the following evaluation was performed.

[Formation of image for evaluation]
The obtained two-component developer was put into a developing device of a test printer obtained by removing a fixing device from a commercially available printer (trade name: LIBRE AR-S505, manufactured by Sharp Corporation), and was subjected to Japanese Industrial Standard (JIS). ) On the A4 size recording paper defined in P0138, the toner adhesion amount is adjusted to 0.6 mg / cm ^2, and the rectangular solid image portion 20 mm long and 50 mm wide is unfixed. Formed. An unfixed toner image formed was fixed by using an external fixing machine at a recording paper passing speed of 120 mm / sec (120 mm / sec) to form an evaluation image. For the external fixing machine, an oil-less fixing device taken out from a commercially available full-color copying machine (trade name: LIBRE AR-C260, manufactured by Sharp Corporation) is set so that the surface temperature of the heating roller can be set to an arbitrary value. A modified version was used. Here, the oilless type fixing device is a fixing device that performs fixing without applying a release agent such as silicone oil to the heating roller.

[High temperature offset resistance evaluation]
Whether or not the high temperature offset phenomenon has occurred by visually observing whether or not the toner image is retransferred from the heating roller to the white background portion to be the white background of the recording paper. It was judged. This operation is repeated by sequentially increasing the surface temperature of the heating roller from 100 ° C. to 210 ° C. in increments of 5 ° C., and the maximum temperature of the heating roller surface temperature (hereinafter referred to as the maximum fixing temperature) at which no high temperature offset phenomenon occurs. Asked. In the evaluation of high temperature offset resistance, the case where the maximum fixing temperature was 190 ° C. or higher was evaluated as good (◯), and the case where the maximum fixing temperature was less than 190 ° C. was evaluated as poor (×).

[Non-offset evaluation]
Similarly to the evaluation of the high temperature offset resistance, the surface temperature of the heating roller is sequentially increased from 100 ° C. to 210 ° C. by 5 ° C. to form an image, and the low temperature offset phenomenon in which the toner image is not fixed on the recording paper, A non-offset region where no high temperature offset phenomenon in which the toner image is retransferred from the heating roller to the white background portion to be white background was examined to evaluate the offset resistance. The non-offset range is the lowest fixing temperature (° C) that is the lowest temperature of the heating roller that does not cause the low temperature offset phenomenon, and the highest fixing temperature (° C) that is the highest temperature of the surface of the heating roller that does not cause the high temperature offset phenomenon. It is obtained from the temperature difference. In the evaluation of the non-offset region, the case where the non-offset region was 40 ° C. or higher was evaluated as good (◯), and the case where the non-offset region was less than 40 ° C. was evaluated as defective (×).

[Image density]
For the image formed when the surface temperature of the heating roller is 170 ° C., the reflection density meter (trade name: RD918, manufactured by Macbeth Co.) is used to measure the optical reflection density of the solid image portion. did. A case where the image density was 1.40 or more was evaluated as good (◯), and a case where the image density was less than 1.40 was evaluated as defective (×).

〔Comprehensive evaluation〕
A comprehensive evaluation was performed by combining the results of the high temperature offset resistance evaluation, the non-offset area evaluation, and the image density evaluation. In the comprehensive evaluation, a case where there was no item evaluated as defective (×) was evaluated as good (◯), and a case where there were one or more items evaluated as defective (×) was evaluated as defective (×). .

The above evaluation results are shown in Table 1. In Table 1, the volume average particle diameter of the toner particles is expressed as “D ₅₀ ”.

  From Table 1, the toners of Examples 1 to 3 produced by the production method of the present invention in which the raw material contains a compatibilizing agent for compatibilizing the binder resin and the release agent and are melt-kneaded are The residual ratio of the release agent in the toner particles relative to the release agent content is high, and the maximum fixing temperature is 190 ° C. or higher. It was excellent in properties. In addition, the residual ratio of the release agent having a melting point lower than the softening point of the binder resin can be increased, and the softening point of the toner as a whole can be lowered. The temperature at which the low temperature offset phenomenon does not occur can be further lowered, and a wide non-offset region of 40 ° C. or higher can be secured.

  It can also be seen that the toners of Examples 1 to 3 have a small coefficient of variation of 33 or less, a narrow particle size distribution and a uniform particle size, and a volume average particle size of 6.8 μm or less. It can be seen that the toners of Examples 1 to 3 have uniform charging performance, excellent transferability, and can form an image having a high image density of 1.40 or more in terms of optical reflection density.

  The toners of Comparative Examples 1 and 2 produced by granulating in an aqueous medium without containing a compatibilizing agent for compatibilizing the binder resin and the release agent in the raw material were produced in the aqueous medium. It was found that the formation of the particles is not inferior to the toners of Examples 1 to 3 in terms of the coefficient of variation and the reduction in the toner diameter, and an image having a high image density can be formed. However, in the toners of Comparative Examples 1 and 2, the residual ratio of the release agent is lower than that of the toners of Examples 1 to 3, and the toners of Examples 1 to 3 have a high temperature offset resistance and a wide non-offset area. It was inferior to toner.

  As described above, according to the method for producing the toner of the present invention, the raw material contains a compatibilizing agent for compatibilizing the binder resin and the release agent, and is melt kneaded and granulated in an aqueous medium. Thus, high temperature offset can be prevented and a toner having a narrow particle size distribution can be obtained.

FIG. 6 is a process diagram illustrating a procedure of a toner manufacturing method according to an embodiment of the present invention.

Claims (5)

The binder resin is softened by melting and kneading a raw material containing a binder resin, a colorant, a release agent, and a compatibilizer for compatibilizing the binder resin and the release agent. A melt-kneading step for dispersing raw materials other than the binder resin;
Granulation to obtain toner particles by softening the binder resin of the resin kneaded product obtained by the melt-kneading step in an aqueous medium containing a dispersant and water and dispersing the resin kneaded material in the aqueous medium to form particles A process for producing a toner comprising the steps of: The compatibilizer is
2. The toner production method according to claim 1, wherein the raw material contains 1 part by weight or more and 10 parts by weight or less based on 100 parts by weight of the binder resin. The release agent is contained in the 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.
3. The method for producing a toner according to claim 2, wherein the compatibilizing agent is contained in the raw material at a ratio of 0.1 to 10 parts by weight with respect to 100 parts by weight of the release agent.   The toner production method according to claim 1, wherein the binder resin is a polyester resin.   The method for producing a toner according to claim 1, wherein the dispersant is a water-soluble polymer compound.

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