JP2017181742A - Toner for electrostatic charge image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development that can achieve higher image quality while ensuring low-temperature fixability and cleaning property.SOLUTION: There is provided a toner for electrostatic charge image development including toner base particles containing at least a binder resin containing a crystalline resin, a mold release agent, and carbon black, wherein the content of the carbon black relative to the toner base particles is 6 to 15 mass%; the coefficient of variation (CV value) in a particle size distribution based on volume of the toner base particles is 16 to 19%; when the dielectric loss tangent tanδ obtained by measuring a frequency range of 1 kHz to 100 kHz in an environment of a temperature of 20°C and relative humidity of 50%RH has the maximum value tanδand the minimum value tanδ, the following formula (1) is satisfied.SELECTED DRAWING: None

Description

  The present invention relates to a toner for developing an electrostatic image.

  In recent years, electrophotographic image forming apparatuses have been used as ordinary copying machines and printers for printing office documents or as simple copies, to the field of creating printed materials for office use, specifically electronic data. Since variable information can be easily printed, the application has been expanded to the on-demand printing (POD) market, which is a light printing area.

  With the spread of applications to the light printing field, market demands for securing a wider color reproduction area are increasing. As a color toner for forming such a color image, a yellow toner, a magenta toner, a cyan toner, or the like containing a binder resin (binder resin) made of a thermoplastic resin and a colorant of each color is used. ing.

  On the other hand, the consumption of black toner is still the largest for use in printing office documents and the like, and carbon black is generally used as the black colorant.

  In recent years, in order to cope with various user usage environments and use image modes, it has been a challenge to form excellent images. By increasing the amount of carbon black in the toner, the cost can be reduced. Further improvement in image quality has become a more important issue.

  As a technique for solving such a problem, for example, in Patent Documents 1 to 3, a toner base particle containing a binder resin and carbon black, and a toner having at least an inorganic fine powder, a particle size distribution of the toner particles, A technique for setting a dielectric loss tangent tan δ, an acid value, an average circularity of toner particles, and the like within a predetermined range is disclosed.

Japanese Patent Laid-Open No. 2004-078206 JP 2002-31635 A JP 2010-059442 A

  However, the above conventional toner has a problem that the image quality deteriorates, and a technology capable of realizing high image quality while ensuring low-temperature fixability and cleanability is demanded for toner filled with carbon black. It was. SUMMARY OF THE INVENTION An object of the present invention is to provide a toner for developing an electrostatic charge image that can achieve higher image quality while ensuring low-temperature fixability and cleanability.

The present inventors have conducted intensive research to solve the above problems. As a result, the toner for developing an electrostatic image includes a binder resin containing a crystalline resin, a release agent, and toner base particles having at least carbon black, and the toner base particles have a carbon black content of 6; -15% by mass, the coefficient of variation (CV value) in the volume-based particle size distribution of the toner base particles is 16 to 19%, and the temperature is 20 ° C. and the relative humidity is 50% RH. The electrostatic charge image developing toner satisfying the following formula (1) is solved when the maximum value of the dielectric tangent tan δ obtained by measurement in the frequency range is tan δ _max and the minimum value is tan δ _min. As a result, the present invention has been completed.

  According to the present invention, there is provided an electrostatic image developing toner capable of realizing further high image quality while ensuring low-temperature fixability and cleanability.

The present invention relates to an electrostatic charge image developing toner comprising a binder resin containing a crystalline resin, a release agent, and toner base particles having at least carbon black, wherein the toner base particles have a carbon black content. 6 to 15% by mass, the coefficient of variation (CV value) in the volume-based particle size distribution of the toner base particles is 16 to 19%, and the temperature is 20 ° C. and the relative humidity is 50% RH, from 1 kHz to 100 kHz. The electrostatic charge image developing toner satisfies the following formula (1) when the maximum value of the dielectric tangent tan δ obtained by measurement in the frequency range of tan δ _max is tan δ _max and the minimum value is tan δ _min . The electrostatic charge image developing toner of the present invention having such a configuration can realize further higher image quality while ensuring low temperature fixability and cleanability.

In the present invention, the carbon black content in the toner base particles is set to a relatively high level of 6 to 15% by mass. For the purpose of reducing CO ₂ emission by reducing the amount of adhered toner, fixing at a low temperature, improving the image density of a solid portion, and the like, a technique for highly filling a colorant (carbon black) in the toner has been studied. In particular, when the colorant in the toner is highly filled, the image density can be increased as compared with the case where an image is formed with the same mass as the toner having a low colorant filling. Therefore, from the viewpoints of reducing the toner cost per copy and reducing the relief of the image (image irregularities), it is desired to fill the toner with a high colorant.

  However, when carbon black is highly filled, carbon black has electrical conductivity, so the aggregate of carbon black becomes an electrical leak point, and the chargeability, developability, transferability, etc. are reduced, and the image quality is reduced. There was a problem to do. In addition, if a crystalline resin is used as the binder resin for the purpose of securing low temperature fixability, the crystalline resin is likely to become an electrical leak point due to the uniform molecular orientation, and this also reduces the chargeability. There was a problem. Further, since the carbon black aggregates are formed, the presence of the colorant (carbon black) in the image becomes non-uniform so that the image density is lowered. For this reason, there has been a demand for a technology capable of realizing high image quality (improving graininess and image density) while ensuring low-temperature fixability in a toner filled with carbon black.

To solve such a problem, the toner for developing an electrostatic charge image of the present invention has a dielectric loss tangent tanδ obtained by measuring in a frequency range from 1 kHz to 100 kHz in an environment of a temperature of 20 ° C. and a relative humidity of 50% RH. When the maximum value is tan δ _max and the minimum value is tan δ _min , the above formula (1) is satisfied.

  The ideal state as the electrical characteristics of the toner is that the electric charge can be retained when an electric field of any frequency is applied. The dielectric loss tangent tan δ is calculated by ε ″ / ε ′, ε ′ means the storage capacity of electric energy, ε ″ means the loss of electric energy, and the value of tan δ, which is the ratio of these, is It can be said that the smaller the value, the easier it is to hold the charge. In addition, the smaller the frequency dependency of tan δ, the easier it is to hold charges in various processes such as the development process and the transfer process in response to the electric field to which the toner is applied, thereby improving the reproducibility of the latent image. Can do.

  The electrostatic image developing toner of the present invention satisfying the above formula (1) has good dispersibility of carbon black and crystalline resin in the toner base particles, suppresses the conductivity inside the toner, and does not depend on the frequency. tan δ takes a substantially constant value (small frequency dependence). Therefore, even when electric fields of various frequencies are applied, it is possible to stably hold charges, respond faithfully in the development process and transfer process, and achieve high image quality while ensuring low temperature fixability. it can.

  The toner for developing an electrostatic charge image of the present invention has a coefficient of variation (CV value) in the volume-based particle size distribution of the toner base particles of 16 to 19%. The electrostatic charge image developing toner of the present invention having such a CV value can ensure cleaning properties. Moreover, since it has a relatively uniform particle size distribution, it is possible to faithfully reproduce the electrostatic latent image and obtain a higher quality image.

  In addition, said mechanism is based on estimation and this invention is not restrict | limited to the said mechanism at all.

  Embodiments of the present invention will be described below. In addition, this invention is not limited only to the following embodiment. Unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50% RH. In the present specification, the toner for developing an electrostatic charge image of the present invention may be simply referred to as “the toner of the present invention” or “the toner”.

  The components of the toner of the present invention will be described.

[Toner base particles]
The toner base particles are particles having at least a binder resin containing a crystalline resin, a release agent, and carbon black, and, if necessary, particles containing other additives (internal additives). . The toner is completed by adding an external additive to the toner base particles.

<Binder resin>
The binder resin according to the present invention includes a crystalline resin. By allowing a crystalline resin having a good affinity for carbon black to be present in a predetermined ratio in the binder resin, the carbon black in the toner base particles is maintained without being aggregated, and the dielectric loss tangent tan δ is within a predetermined range. To fit.

(Crystalline resin)
In the present invention, the crystalline resin means a resin having a clear endothermic peak in a DSC curve measured using the above-mentioned differential scanning calorimeter “Diamond DSC” (manufactured by PerkinElmer). Examples of the crystalline resin include a crystalline polyester resin, a crystalline polyurethane resin, a crystalline polyurea resin, a crystalline polyamide resin, a crystalline polyether resin, and the like. It is preferable to use a conductive polyester resin. Therefore, according to a preferred embodiment of the present invention, the crystalline resin is a crystalline polyester resin. Hereinafter, the crystalline polyester resin will be described.

(Crystalline polyester resin)
The crystalline polyester resin is a known polyester resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyhydric carboxylic acid component) and a divalent or higher alcohol (polyhydric alcohol component). A resin having

  The melting point of the crystalline polyester resin is preferably 55 ° C. or higher and 90 ° C. or lower, more preferably 70 ° C. or higher and 85 ° C. or lower. When the melting point of the crystalline polyester resin is in the above range, sufficient low-temperature fixability can be obtained. The melting point of the crystalline polyester resin can be controlled by the resin composition.

  The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 5,000 to 100,000, more preferably 10,000 to 80,000, and 15,000 to 50,000. Particularly preferred. The number average molecular weight (Mn) is preferably 2,000 to 20,000, and more preferably 3,000 to 15,000.

  The valences of the polyvalent carboxylic acid component and the polyhydric alcohol component are each preferably 2 to 3, particularly preferably 2 respectively. Therefore, when the valence is 2 respectively as a particularly preferable form (that is, dicarboxylic acid) The acid component and diol component) will be described.

  As the dicarboxylic acid component, an aliphatic dicarboxylic acid is preferably used, and an aromatic dicarboxylic acid may be used in combination. As the aliphatic dicarboxylic acid, it is preferable to use a linear one. By using a linear type, there is an advantage that crystallinity is improved. The dicarboxylic acid component is not limited to one type, and two or more types may be mixed and used.

  Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid. Acid (dodecanedioic acid), 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1, Examples thereof include 18-octadecanedicarboxylic acid.

  Among the above aliphatic dicarboxylic acids, aliphatic dicarboxylic acids having 6 to 14 carbon atoms are preferable because the effects of the present invention are easily obtained as described above. Examples of the aromatic dicarboxylic acid that can be used together with the aliphatic dicarboxylic acid include phthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-biphenyl. And dicarboxylic acid. Among these, terephthalic acid, isophthalic acid, and t-butylisophthalic acid are preferably used from the viewpoints of availability and emulsification ease. In addition, trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid, anhydrides of the above carboxylic acid compounds, or alkyl esters having 1 to 3 carbon atoms may be used.

  As the dicarboxylic acid component for forming the crystalline polyester resin, the aliphatic dicarboxylic acid content is preferably 50 constituent mol% or more, more preferably 70 constituent mol% or more, and still more preferably 80 It is at least 100% by mole, particularly preferably 100% by mole. When the content of the aliphatic dicarboxylic acid in the dicarboxylic acid component is 50 constituent mol% or more, the crystallinity of the crystalline polyester resin can be sufficiently ensured.

  Moreover, it is preferable to use aliphatic diol as a diol component, and you may contain diols other than aliphatic diol as needed. As the aliphatic diol, a linear diol is preferably used. By using a linear type, there is an advantage that crystallinity is improved. A diol component may be used individually by 1 type, and may be used 2 or more types.

  Examples of the aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7- Heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14- Tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol, neopentyl glycol, and the like can be given.

  As the diol component for forming the crystalline polyester resin, the content of the aliphatic diol is preferably 50 component mol% or more, more preferably 70 component mol% or more, and still more preferably 80 component mol%. % Or more, and particularly preferably 100 constituent mol%. When the content of the aliphatic diol in the diol component is 50 constituent mol% or more, the crystallinity of the crystalline polyester resin can be ensured, and excellent low-temperature fixability can be obtained in the manufactured toner. Glossiness can be obtained in an image formed automatically.

  The use ratio of the diol component to the dicarboxylic acid component is such that the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] of the diol component to the carboxyl group [COOH] of the dicarboxylic acid component is 2.0 / 1. It is preferable that it is 0.0-1.0 / 2.0.

  In the present invention, the acid value of the crystalline polyester resin is preferably 4.0 mgKOH / g or more, more preferably 6.0 mgKOH / g or more, still more preferably 15 mgKOH / g or more, and preferably 33 mgKOH / g. Hereinafter, it is more preferably 30 mgKOH / g or less. That is, in a preferred embodiment of the present invention, the crystalline polyester resin has an acid value of 15 to 30 mgKOH / g. Within such a range, the affinity between the crystalline resin and carbon black is ensured, the necessary density is output, and a stable image density can be realized over a long period of time during continuous printing.

  The acid value can be controlled by reaction conditions such as the type and composition ratio of the diol component and dicarboxylic acid component, adjustment of the amount of catalyst used in the polycondensation reaction, adjustment of the polymerization initiator, reaction temperature and time. In addition, the longer the reaction time, the higher the molecular weight tends to be, and the lower the acid value.

  The method for producing the crystalline polyester resin is not particularly limited, and may be produced by polycondensation (esterification) of the polyvalent carboxylic acid component and the polyhydric alcohol component using a known esterification catalyst. it can.

Catalysts that can be used in the production of the crystalline polyester resin include alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; aluminum, zinc, manganese, antimony, titanium, tin, Metal compounds such as zirconium and germanium; phosphorous acid compounds; phosphoric acid compounds; and amine compounds. Specific examples of tin compounds include dibutyltin oxide (dibutyltin oxide), tin octylate, tin dioctylate, and salts thereof. Titanium compounds include titanium alkoxides such as tetranormal butyl titanate (Ti (On-Bu) ₄ ), tetraisopropyl titanate, tetramethyl titanate and tetrastearyl titanate; titanium acylates such as polyhydroxy titanium stearate; titanium tetra Examples thereof include titanium chelates such as acetylacetonate, titanium lactate, titanium triethanolamate and the like. Examples of germanium compounds include germanium dioxide. Furthermore, examples of the aluminum compound include oxides such as polyaluminum hydroxide, aluminum alkoxide, and the like, and tributylaluminate and the like can be given. You may use these individually by 1 type or in combination of 2 or more types.

  The polymerization temperature is not particularly limited and can be adjusted as appropriate to obtain the desired product, and is preferably 70 to 250 ° C. The polymerization time is not particularly limited, but is preferably 0.5 to 10 hours. During the polymerization, the pressure in the reaction system may be reduced as necessary.

(Hybrid crystalline polyester resin)
In the present invention, the carbon black content in the toner base particles is set to a relatively high level of 6 to 15% by mass. In the present invention, such a crystalline resin having a good affinity for carbon black is present in a predetermined ratio in the binder resin, so that the carbon black in the toner base particles is kept dispersed without being aggregated. be able to.

  In particular, in the present invention, it is preferable to use a hybrid crystalline polyester resin partially containing an amorphous resin structure. The hybrid crystalline polyester resin has a particularly high affinity with carbon black and can exist stably even when adjacent to each other. For this reason, it is considered that each constituent component is difficult to become a domain or an aggregate during the production of toner base particles. That is, according to the present invention, the crystalline polyester resin is more preferably a hybrid crystalline polyester resin.

  In a preferred embodiment of the present invention, the hybrid crystalline polyester resin is a resin in which a crystalline polyester polymer segment and an amorphous polymer segment are chemically bonded. Therefore, according to a preferred embodiment of the present invention, the crystalline resin has a structure in which a crystalline polyester polymer segment and an amorphous polymer segment are chemically bonded. By adopting such a form, affinity with the amorphous resin (main binder) is improved in the toner, and uneven distribution of the crystalline polyester resin is suppressed. Further, it is presumed that by controlling the crystallinity, it has a technical effect of improving environmental stability.

  There are no particular restrictions on the chemically bonded structure, but the crystalline polyester polymerized segment is preferably grafted with the amorphous polymerized segment as the main chain. That is, the hybrid crystalline polyester resin is preferably a graft copolymer having the amorphous polymerization segment as a main chain and the crystalline polyester polymerization segment as a side chain. By adopting such a form, the orientation of the crystalline polyester polymer segment can be further increased, the crystallinity of the hybrid crystalline polyester resin can be further improved, and the dispersibility of the carbon black can be improved. Can do.

  More specifically, the hybrid crystalline polyester resin is preferably a hybrid crystalline polyester resin in which a crystalline polyester polymer segment as a side chain is bonded to the main chain of a styrene acrylic polymer segment as an amorphous polymer segment.

<Crystalline polyester polymerization segment>
A crystalline polyester polymerization segment refers to a portion derived from a crystalline polyester resin. That is, it refers to a molecular chain having the same chemical structure as that constituting the crystalline polyester resin.

  The weight average molecular weight (Mw) of the hybrid crystalline polyester resin is preferably 5,000 to 100,000, more preferably 7,000 to 50,000, and further 8,000 to 40,000. preferable. The number average molecular weight (Mn) is preferably 100 to 50,000, and more preferably 1,000 to 10,000.

  The melting point of the hybrid crystalline polyester resin is preferably 55 ° C. or higher and 90 ° C. or lower, more preferably 65 ° C. or higher and 85 ° C. or lower.

  The crystalline polyester polymerization segment is the same as the above-described crystalline polyester resin, and is a portion derived from a known polyester resin obtained by a polycondensation reaction between the same polyvalent carboxylic acid component and a polyhydric alcohol component. Since the polyvalent carboxylic acid component and the polyhydric alcohol component constituting the crystalline polyester polymerization segment are the same as the above crystalline polyester resin, description thereof is omitted.

  The content of the crystalline polyester polymerization segment is preferably 80% by mass or more and 98% by mass or less, and more preferably 90% by mass or more and 95% by mass or less with respect to the total amount of the hybrid crystalline polyester resin. By setting it as the above range, sufficient crystallinity can be imparted to the hybrid crystalline polyester resin. In addition, the structural component and content rate of each segment in hybrid crystalline polyester resin can be specified by NMR measurement and methylation reaction P-GC / MS measurement, for example.

  The hybrid crystalline polyester resin includes an amorphous polymer segment in addition to the crystalline polyester polymer segment. By using a graft copolymer, the orientation of the crystalline polyester polymer segment can be easily controlled, and sufficient crystallinity can be imparted to the hybrid crystalline polyester resin.

<Amorphous polymerization segment>
The amorphous polymer segment refers to a portion derived from an amorphous resin. That is, it refers to a molecular chain having the same chemical structure as that constituting the amorphous resin. The amorphous polymer segment can contribute to the affinity between the amorphous resin contained in the binder resin in the present invention and the hybrid crystalline polyester resin. Whether the hybrid crystalline polyester resin contains an amorphous polymer segment can be confirmed by specifying the chemical structure using, for example, NMR measurement or methylation reaction P-GC / MS measurement.

  The amorphous polymer segment does not have a melting point and has a relatively high glass transition temperature (Tg) when differential scanning calorimetry (DSC) is performed on a resin having the same chemical structure and molecular weight as the segment. It is a polymerization segment.

  The content of the amorphous polymer segment is preferably 2% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 10% by mass or less in the hybrid crystalline polyester resin. By setting it as the above range, sufficient crystallinity can be imparted to the hybrid crystalline polyester resin.

  The amorphous polymer segment is preferably composed of the same type of resin as the amorphous resin when the binder resin in the present invention contains an amorphous resin. By adopting such a form, the affinity between the hybrid crystalline polyester resin and the binder resin as a matrix is further improved.

  Here, “the same kind of resin” means that a characteristic chemical bond is commonly contained in the repeating unit. Here, “characteristic chemical bond” is described in the National Institute for Materials Science (NIMS) Substance / Material Database (http://polymer.nims.go.jp/PoLyInfo/guide/jp/term_polymer.html). According to “Polymer classification”. That is, polyacryl, polyamide, polyanhydride, polycarbonate, polydiene, polyester, polyhaloolefin, polyimide, polyimine, polyketone, polyolefin, polyether, polyphenylene, polyphosphazene, polysiloxane, polystyrene, polysulfide, polysulfone, polyurethane, polyurea Chemical bonds constituting polymers classified by a total of 22 types of polyvinyl and other polymers are referred to as “characteristic chemical bonds”.

  Further, in the case where the resin is a copolymer, the “same kind of resin” refers to a monomer type having the above chemical bond as a structural unit in the chemical structure of a plurality of monomer types constituting the copolymer. In this case, it refers to resins having a characteristic chemical bond in common. Therefore, even if the characteristics of the resins themselves are different from each other, and even when the molar component ratios of the monomer species constituting the copolymer are different from each other, they must have a characteristic chemical bond in common. Considered the same kind of resin.

  For example, a resin (or polymerized segment) formed of styrene, butyl acrylate and acrylic acid and a resin (or polymerized segment) formed of styrene, butyl acrylate and methacrylic acid have chemical bonds constituting at least polyacryl. These are the same kind of resins.

  The resin component constituting the amorphous polymer segment is not particularly limited, and examples thereof include a vinyl polymer segment, a urethane polymer segment, and a urea polymer segment. Among these, a vinyl polymer segment is preferable because it is easy to control thermoplasticity.

  Although it will not restrict | limit especially if a vinyl compound is superposed | polymerized as a vinyl polymerization segment, For example, an acrylic ester polymerization segment, a styrene-acrylic ester polymerization segment, an ethylene-vinyl acetate polymerization segment etc. are mentioned. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Among the above vinyl polymerized segments, a styrene-acrylic acid ester polymerized segment (styrene acrylic polymerized segment) is preferable in consideration of plasticity during heat fixing. Therefore, hereinafter, the styrene acrylic polymer segment as the amorphous polymer segment will be described.

The styrene acrylic polymer segment is formed by addition polymerization of at least a styrene monomer and a (meth) acrylic acid ester monomer. Styrene monomer as referred to herein, in addition to styrene represented by the structural formula _{CH 2 = CH-C 6 H} 5, is intended to include a structure having a known side-chain or functional groups styrene structure. In addition, the (meth) acrylic acid ester monomer mentioned here is an acrylic acid ester compound represented by CH ₂ = CHCOOR (R is an alkyl group) or a methacrylic acid ester compound, an acrylic acid ester derivative or a methacrylic acid ester compound. It includes an ester compound having a known side chain or functional group in the structure of an acid ester derivative or the like.

  Specific examples of styrene monomer and (meth) acrylic acid ester monomer capable of forming a styrene acrylic polymer segment are shown below, but can be used for forming a styrene acrylic polymer segment used in the present invention. Is not limited to the following.

  First, specific examples of the styrene monomer include, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4- Examples thereof include dimethyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, and pn-dodecyl styrene. These styrene monomers can be used alone or in combination of two or more.

  Specific examples of the (meth) acrylic acid ester monomer include, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate. Acrylate monomers such as stearyl acrylate, lauryl acrylate, and phenyl acrylate; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, Stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl meta Relate, methacrylic acid esters such as dimethyl aminoethyl methacrylate. Of these, it is preferable to use a long-chain acrylate monomer. Specifically, methyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are preferable.

  In this specification, “(meth) acrylic acid ester monomer” is a general term for “acrylic acid ester monomer” and “methacrylic acid ester monomer”. “Methyl acrylate” is a generic term for “methyl acrylate” and “methyl methacrylate”.

  These acrylic acid ester monomers or methacrylic acid ester monomers can be used alone or in combination of two or more. That is, a copolymer is formed using a styrene monomer and two or more acrylate monomers, and a copolymer is formed using a styrene monomer and two or more methacrylic ester monomers. Either a coalescence can be formed, or a copolymer can be formed by using a styrene monomer together with an acrylate monomer and a methacrylic acid ester monomer.

  The content of the structural unit derived from the styrene monomer in the amorphous polymerization segment is preferably 40 to 90% by mass with respect to the total amount of the amorphous polymerization segment. Moreover, it is preferable that the content rate of the structural unit derived from the (meth) acrylic acid ester monomer in an amorphous polymerization segment is 10-60 mass% with respect to the whole quantity of an amorphous polymerization segment.

  Furthermore, it is preferable that the amorphous polymerized segment is obtained by addition polymerization of a compound for chemically bonding to the crystalline polyester polymerized segment in addition to the styrene monomer and the (meth) acrylic acid ester monomer. Specifically, it is preferable to use a compound which is ester-bonded to a hydroxyl group [—OH] derived from a polyhydric alcohol component or a carboxyl group [—COOH] derived from a polyvalent carboxylic acid component contained in the crystalline polyester polymerization segment. . Therefore, the amorphous polymerization segment can be addition-polymerized with respect to the styrene monomer and the (meth) acrylate monomer, and has a carboxyl group [—COOH] or a hydroxyl group [—OH]. It is preferable to further polymerize the compound.

  Examples of such compounds include compounds having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester; 2-hydroxy Ethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate And compounds having a hydroxyl group such as polyethylene glycol mono (meth) acrylate.

  The content rate of the structural unit derived from the said compound in an amorphous polymerization segment is preferable in it being 0.5-20 mass% with respect to the whole quantity of an amorphous polymerization segment.

  The method for forming the styrene acrylic polymer segment is not particularly limited, and examples thereof include a method of polymerizing a monomer using a known oil-soluble or water-soluble polymerization initiator. Specific examples of the oil-soluble polymerization initiator include the following azo or diazo polymerization initiators and peroxide polymerization initiators.

  As the azo or diazo polymerization initiator, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1) -Carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and the like.

  Examples of peroxide polymerization initiators include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2, Examples include 4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4,4-t-butylperoxycyclohexyl) propane, and tris- (t-butylperoxy) triazine.

  Moreover, when forming resin particles by an emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and salts thereof, and hydrogen peroxide.

(Method for producing hybrid crystalline polyester resin)
The method for producing a hybrid crystalline polyester resin contained in the binder resin according to the present invention is capable of forming a polymer having a structure in which the crystalline polyester polymer segment and the amorphous polymer segment are chemically bonded. The method is not particularly limited. Specific methods for producing the hybrid crystalline polyester resin include, for example, the methods shown below.

(A) A method for producing a hybrid crystalline polyester resin by polymerizing an amorphous polymer segment in advance and performing a polymerization reaction to form a crystalline polyester polymer segment in the presence of the amorphous polymer segment. First, an amorphous polymerization segment is prepared by addition-reacting a monomer (preferably, a styrene monomer and a vinyl monomer such as a (meth) acrylic acid ester monomer) constituting the above-described amorphous polymerization segment. Form. Next, in the presence of the amorphous polymerization segment, a polyvalent carboxylic acid component and a polyhydric alcohol component are polymerized to form a crystalline polyester polymerization segment. At this time, the polyvalent carboxylic acid component and the polyhydric alcohol component are subjected to a condensation reaction, and the amorphous crystalline segment is subjected to an addition reaction of the polyvalent carboxylic acid component or the polyhydric alcohol component. Is formed.

  In the above method, it is preferable to incorporate a site where these segments can react with each other in the crystalline polyester polymerized segment or the amorphous polymerized segment. Specifically, when forming the amorphous polymer segment, in addition to the monomer constituting the amorphous polymer segment, the carboxyl group [—COOH] or hydroxyl group [—OH] remaining in the crystalline polyester polymer segment Also used are compounds having a site capable of reacting with and a site capable of reacting with the amorphous polymerized segment. That is, when this compound reacts with a carboxyl group [—COOH] or a hydroxyl group [—OH] in the crystalline polyester polymerization segment, the crystalline polyester polymerization segment may be chemically bonded to the amorphous polymerization segment. it can.

  Alternatively, a compound having a site capable of reacting with a polyhydric alcohol component or a polyvalent carboxylic acid component and capable of reacting with an amorphous polymer segment may be used during the formation of the crystalline polyester polymer segment.

  By using the above method, a hybrid crystalline polyester resin having a structure (graft structure) in which a crystalline polyester polymer segment is chemically bonded to an amorphous polymer segment can be formed.

  The method (a) is preferable because it is easy to form a hybrid crystalline polyester resin having a structure in which a crystalline polyester polymer segment is grafted to an amorphous polymer segment, and the production process can be simplified. In the method (a), since the amorphous polymer segment is bonded after the amorphous polymer segment is formed in advance, the orientation of the crystal polyester segment tends to be uniform. Therefore, it is preferable because a hybrid crystalline polyester resin suitable for the toner defined in the present invention can be reliably formed.

  In addition, (b) a method in which a crystalline polyester polymer segment and an amorphous polymer segment are formed in advance and these are combined to produce a hybrid crystalline polyester resin may be used. A method may be used in which a polyester polymerization segment is formed in advance and a hybrid crystalline polyester resin is produced by performing a polymerization reaction in which an amorphous polymerization segment is formed in the presence of the crystalline polyester polymerization segment.

  By using the above method, a hybrid crystalline polyester resin having a structure (graft structure) in which a crystalline polyester polymer segment is chemically bonded to an amorphous polymer segment can be formed.

  The content of the crystalline polyester resin in the toner base particles is preferably 5 to 15% by mass, and more preferably 7 to 12% by mass. Within this range, the low-temperature fixability is good and the chargeability of the toner is also improved.

[Amorphous resin]
The toner base particles according to the present invention preferably contain an amorphous resin. The amorphous resin is preferably composed of the same kind of resin or amorphous polyester resin as the amorphous polymer segment of the hybrid crystalline polyester resin, which is the preferred crystalline resin. Here, “consisting of the same kind of resin” may be a form consisting of only the same kind of resin, or a form including not only the same kind of resin but also other amorphous resins. Also good. However, in the case of a form containing the same type of resin and another amorphous resin, the content of the same type of resin is preferably 15% by mass or more, and 20% by mass or more with respect to the total amount of the amorphous resin. Is more preferable.

  Among the amorphous resins, a vinyl resin or a styrene acrylic modified polyester resin is preferable, and a vinyl resin is more preferable. Therefore, according to a preferred embodiment of the present invention, the binder resin contains a vinyl resin. By including the vinyl resin, the affinity between the binder resin and the release agent is improved, and the fixing property is improved.

  The weight average molecular weight (Mw) is preferably 5,000 to 150,000, and preferably 10,000 to 90,000, from the viewpoint that the amorphous resin or the amorphous polyester resin can easily control the plasticity. More preferably.

  The number average molecular weight (Mn) of the amorphous resin or amorphous polyester resin is preferably 3,000 to 30,000, and more preferably 5,000 to 25,000. The amorphous resin preferably has a glass transition temperature (Tg) of 25 to 70 ° C, and preferably 35 to 65 ° C. The softening point temperature is preferably 75 to 130 ° C, more preferably 85 to 115 ° C.

[Vinyl resin]
The vinyl resin is not particularly limited as long as a vinyl compound is polymerized, and examples thereof include (meth) acrylic acid ester resins, styrene acrylic copolymers, ethylene / vinyl acetate resins, and the like. These may be used individually by 1 type and may be used in combination of 2 or more type. Among the vinyl resins mentioned above, consideration is given to manufacturability in the emulsion aggregation method (that is, a toner having a desired particle size distribution can be obtained by making a latex having a uniform aggregation property) and plasticity during heat fixing. Then, a styrene acrylic copolymer is preferable.

(Styrene acrylic copolymer)
The styrene acrylic copolymer referred to in the present invention is formed by performing polymerization using at least a styrene monomer and a (meth) acrylic acid ester monomer. Here, the styrene monomer includes not only styrene represented by the structural formula of CH ₂ ═CH—C ₆ H ₅ but also a structure having a known side chain or functional group in the styrene structure.

The (meth) acrylic acid ester monomer has a functional group having an ester bond in the side chain. _{Specifically,} CH 2 = CHCOOR (R is an alkyl group) other acrylic acid ester monomer represented _by, methacrylic acid ester represented by _{CH 2 = C (CH 3)} COOR (R is an alkyl group) Vinyl-based ester compounds such as monomers are included.

  Specific examples of the styrene monomer and (meth) acrylic acid ester monomer that can form a styrene acrylic copolymer are shown below, but are not limited to those shown below.

  Examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p- Examples thereof include tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, and pn-dodecyl styrene.

  The (meth) acrylic acid ester monomer is typically the following acrylic acid ester monomer and methacrylic acid ester monomer. Examples of the acrylic acid ester monomer include methyl acrylate, Examples include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate phenyl. Examples of the methacrylic acid ester monomer include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate. Lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate and the like.

  These styrene monomers, acrylic acid ester monomers, or methacrylic acid ester monomers can be used singly or in combination of two or more.

  In addition to the copolymer formed only with the styrene monomer and (meth) acrylate monomer described above, the styrene acrylic copolymer includes these styrene monomer and (meth) acrylate ester. In addition to the monomers, some are formed using a common vinyl monomer. Although the vinyl monomer which can be used together when forming the styrene acrylic copolymer said by this invention is illustrated below, the vinyl monomer which can be used together is not limited to what is shown below.

(1) Olefins Ethylene, propylene, isobutylene, etc. (2) Vinyl esters Vinyl propionate, vinyl acetate, vinyl benzoate, etc. (3) Vinyl ethers Vinyl methyl ether, vinyl ethyl ether, etc. (4) Vinyl ketones Vinyl methyl ketone, Vinyl ethyl ketone, vinyl hexyl ketone, etc. (5) N-vinyl compounds N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, etc. (6) Other vinyl compounds such as vinyl naphthalene, vinyl pyridine, acrylonitrile, methacrylo Acrylic acid or methacrylic acid derivatives such as nitrile and acrylamide.

  It is also possible to produce a crosslinked resin using a polyfunctional vinyl monomer. Furthermore, it is also possible to use a vinyl monomer having an ionic dissociation group in the side chain. Specific examples of the ionic dissociation group include a carboxyl group, a sulfonic acid group, and a phosphoric acid group. Specific examples of these vinyl monomers having an ionic dissociation group are shown below.

  Specific examples of the vinyl monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, and the like. .

  The method for forming the styrene acrylic copolymer is not particularly limited, and examples thereof include a method of polymerizing a monomer using a known oil-soluble or water-soluble polymerization initiator. Specific examples of the oil-soluble polymerization initiator or the water-soluble polymerization initiator are the same as those described above, and thus the description thereof is omitted here. A known chain transfer agent such as n-octyl-3-mercaptopropionate may be used as necessary.

  When forming the styrene acrylic copolymer used in the present invention, the content of the styrene monomer and the acrylate monomer is not particularly limited, and the softening point temperature and glass transition temperature of the binder resin. It is possible to adjust as appropriate from the viewpoint of adjusting. Specifically, the content of the styrene monomer is preferably 40 to 95% by mass and more preferably 50 to 80% by mass with respect to the whole monomer. Moreover, 5-60 mass% is preferable with respect to the whole monomer, and, as for content of an acrylic ester monomer, 10-50 mass% is more preferable.

  The molecular weight of the styrene acrylic copolymer is preferably 2,000 to 1,000,000 in terms of weight average molecular weight (Mw). Further, the number average molecular weight (Mn) is preferably 1,000 to 100,000. Moreover, 1.5-100 are preferable and, as for molecular weight distribution (Mw / Mn), 1.8-70 are more preferable. Fixing step when printing is performed using the prepared toner by setting the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the styrene acrylic copolymer within the above ranges. This is effective in suppressing the occurrence of the offset phenomenon. The glass transition temperature of the styrene acrylic copolymer is preferably 30 to 70 ° C, and the softening point temperature is preferably 80 to 170 ° C. When the glass transition temperature and the softening point temperature are in the above ranges, good fixability can be obtained.

[Amorphous polyester resin]
Amorphous polyester resin is obtained by polycondensation reaction using polyvalent carboxylic acid component (or derivative thereof) and polyhydric alcohol component (or derivative thereof) as raw materials, and has no clear melting point Say.

  As the derivative of the polyvalent carboxylic acid component, alkyl ester, acid anhydride and acid chloride of the polyvalent carboxylic acid component can be used, and as the derivative of the polyhydric alcohol component, the ester compound of the polyhydric alcohol component and hydroxy Carboxylic acid can be used.

  Examples of the polyvalent carboxylic acid component include oxalic acid, succinic acid, maleic acid, mesaconic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid Acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucoic acid, Phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycol Glycolic acid, diphenylacetic acid, diphenyl-p divalent carboxylic acids such as p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, dodecenyl succinic acid; trimellitic acid And divalent or higher carboxylic acids such as pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid.

  Examples of the polyhydric alcohol component include ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, etc. And trivalent or higher polyols such as glycerin, pentaerythritol, hexamethylol melamine, hexaethylol melamine, tetramethylol benzoguanamine, and tetraethylol benzoguanamine.

  Various conventionally known catalysts can be used as the catalyst for synthesizing the amorphous polyester resin.

  The number average molecular weight (Mn) and the weight average molecular weight (Mw) of the binder resin constituting the toner can be calculated by a molecular weight measurement method. Hereinafter, a molecular weight measurement procedure by gel permeation chromatography (GPC) using tetrahydrofuran (THF), which is one of typical examples of the molecular weight measurement method, as a column solvent will be described.

  Specifically, 1 ml of THF (using a degassed sample) is added to 1 mg of a measurement sample, and the mixture is sufficiently dissolved by stirring with a magnetic stirrer at room temperature. Next, after processing with a membrane filter having a pore size of 0.45 to 0.50 μm, it is injected into the GPC apparatus.

  The measurement conditions of GPC are measured by stabilizing the column at 40 ° C., flowing THF at a flow rate of 1 ml / min, and injecting about 100 μl of a sample having a concentration of 1 mg / ml. As the column, it is preferable to use a combination of commercially available polystyrene gel columns. For example, Shodex GPC KF-801, 802, 803, 804, 805, 806, 807 made by Showa Denko KK, TSKgel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, GMHXL, manufactured by Tosoh Corporation There are combinations of TSK guard columns.

  As the detector, a refractive index detector (RI detector) or a UV detector is preferably used. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve created using monodisperse polystyrene standard particles. About 10 points are preferably used as polystyrene for preparing a calibration curve.

  The molecular weight measurement can be performed, for example, under the following measurement conditions.

(Measurement condition)
Apparatus: HLC-8020 (manufactured by Tosoh Corporation)
Column: GMHXL × 2, G2000HXL × 1
Detector: At least one of RI and UV Eluent flow rate: 1.0 ml / min Sample concentration: 0.01 g / 20 ml
Sample volume: 100 μl
Calibration curve: Prepared with standard polystyrene.

  The toner base particles according to the present invention may have a single-layer structure or a core-shell structure, but a core-shell structure is preferable. If it is a core-shell structure, heat resistance will improve, maintaining low-temperature fixability. Similarly, from the viewpoint of improving heat resistance while maintaining low-temperature fixability, the shell portion of the core-shell structure is preferably composed of an amorphous polyester resin. Conventionally known knowledge is appropriately adopted as a method for producing toner base particles having a core-shell structure.

  In a preferred embodiment of the present invention, the content of the crystalline resin in the toner base particles is preferably 5 to 15% by mass, and preferably 6 to 13% by mass from the viewpoint of low-temperature fixability and chargeability. More preferably, it is more preferably 7 to 10% by mass. In the preferred embodiment of the present invention, the content of the amorphous resin in the toner base particles is preferably 40 to 90% by mass, and 48 to 87% by mass from the viewpoints of chargeability and fixability. More preferably, it is more preferably 53 to 85% by mass.

[Release agent]
The toner base particles of the present invention contain a release agent (wax). Examples of the mold release agent include hydrocarbon waxes, ester waxes, natural product waxes, amide waxes, and the like. In the toner of the present invention, the release agent preferably contains an ester wax or a hydrocarbon wax. These release agents are suitable for the toner of the present invention. By using these release agents, the fixing and separating properties of the toner can be improved.

  Examples of hydrocarbon waxes include low molecular weight polyethylene wax, polypropylene wax, microcrystalline wax, Fischer-Tropsch wax, and paraffin wax.

  Examples of ester waxes include behenyl behenate, ethylene glycol stearate, ethylene glycol behenate, neopentyl glycol stearate, neopentyl glycol behenate, 1,6-hexanediol stearate, 1,6 -Higher fatty acids such as hexanediol behenate, glycerine stearate, glycerine behenate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, stearyl citrate, behenyl citrate, stearyl ring acid and behenyl ring acid And esters of higher alcohols. Among them, behenyl behenate, pentaerythritol tetrabehenate, fatty acid polyglycerin ester, glycerine behenate, stearyl behenate and the like are preferable from the viewpoints of chargeability and fixability. These release agents can be used alone or in combination of two or more.

  Melting | fusing point of a mold release agent becomes like this. Preferably it is 40-160 degreeC, More preferably, it is 60-100 degreeC. By setting the melting point within the above range, the heat-resistant storage stability of the toner is ensured, and stable toner image formation can be performed without causing cold offset or the like even when fixing at a low temperature. Further, the content of the release agent in the toner base particles is preferably 1 to 30% by mass, and more preferably 3 to 20% by mass.

  In addition, there is no particular limitation on the method of incorporating the release agent into the toner base particles, and the release agent particle dispersion solution is separately prepared and contained by mixing with the dispersion liquid of other constituents of the toner base particles. It may be allowed to be included, or may be included together when the raw material component of the binder resin is polymerized. The former method has a technical effect for improving low-temperature fixability, and the latter method has a technical effect for improving charging property.

[Carbon black (colorant)]
In the present invention, a colorant (black) is used to produce an electrostatic charge image developing toner. As the black colorant, carbon black is used from the viewpoint of colorability and color tone.

  Although it does not restrict | limit especially as carbon black, Furnace black, channel black, acetylene black, thermal black, lamp black, etc. are suitable.

  According to the present invention, the content of the carbon black in the toner base particles is 6 to 15% by mass. If it is less than 6% by mass, the content of the colorant (carbon black) in the image is too small, and the image density is lowered. On the other hand, if it exceeds 15% by mass, the graininess (GI value) decreases. The carbon black content is preferably 7 to 12% by mass.

[Charge control agent]
The toner base particles of the present invention may contain a charge control agent.

  As the charge control agent, various known compounds such as nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, and salicylic acid metal salts can be used. .

  The amount of the charge control agent added is usually 0.1 to 10% by mass, preferably 0.5 to 5% by mass with respect to 100% by mass of the binder resin in the finally obtained toner particles. .

  As a magnitude | size of a charge control agent particle | grain, 10-1000 nm and 50-500 nm are preferable at a number average primary particle diameter, Furthermore, 80-300 nm is especially preferable.

  Other additives include rhodamine dyes, triphenylmethane dyes, alkylamines and the like.

<Particle size of toner base particles>
The toner base particles of the present invention preferably have a median diameter (D ₅₀ ) of 3 to 8 μm. This particle size can be controlled by the concentration of the aggregating agent, the fusing time, the composition of the polymer itself, and the like in the production method described later. When the volume-based median diameter (D ₅₀ ) is 3 to 8 μm, reproducibility of fine lines and high image quality of photographic images can be achieved, and the amount of toner consumed can be reduced when a large particle size toner is used. Can be reduced. The volume-based median diameter (D ₅₀ ) can be measured by, for example, “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.).

<Average circularity of toner base particles>
The toner base particles of the present invention are produced by an emulsion aggregation method. Therefore, the shape of the toner base particles (toner) to be produced is close to a true sphere. The average circularity (simply referred to as circularity) represented by the following formula (4) of the toner base particles of the present invention is usually 0.91 or more. Therefore, according to a preferred embodiment of the present invention, the average circularity is 0.91 or more. From the viewpoint of improvement in transfer efficiency and charging stability, it is preferably 0.920 to 0.995, more preferably 0.930 to 0.975.

  The average circularity can be measured using, for example, an average circularity measuring device “FPIA-2100” (manufactured by Sysmex Corporation).

[External additive]
The toner according to the present invention may include external additive particles. The external additive is not particularly limited, but inorganic particles having a number average primary particle size of about 2 to 800 nm are preferable. The type of external additive is not particularly limited, and examples thereof include known inorganic particles exemplified below and lubricants. These external additives can be used alone or in combination of two or more.

  As the inorganic particles, conventionally known particles can be used. For example, silica, titania (titanium dioxide), alumina, strontium titanate particles, hydrotalcite and the like are preferable. Moreover, what hydrophobized these inorganic particles as needed can also be used.

  Specific examples of the silica particles include, for example, commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., HVK-2150 manufactured by Hoechst, H-200, commercially available products TS-720, TS-530, TS-610, H-5, MS-5 and the like manufactured by Cabot Corporation can be mentioned.

  As titania particles, for example, commercially available products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercially available products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS manufactured by Teika Corporation, JA-1, commercial products manufactured by Fuji Titanium Industry Co., Ltd. TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T, commercial products IT-S, IT-OA, IT manufactured by Idemitsu Kosan Co., Ltd. -OB, IT-OC, etc. are mentioned.

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

  Further, it is possible to use a lubricant to further improve the cleaning property and the transfer property. For example, there are metal salts of higher fatty acids as follows. That is, salts of zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, salts of manganese, iron, copper, magnesium, etc., zinc palmitate, salts of copper, magnesium, calcium, etc., linoleic acid And salts of zinc and calcium of ricinoleic acid.

  The amount of the external additive added (the total amount when two or more types are used) is preferably 0.1 to 10.0% by mass with respect to the toner base particles.

[Dielectric loss tangent of toner tan δ]
In the electrostatic image developing toner of the present invention, the maximum value of the dielectric tangent tan δ obtained by measuring in the frequency range from 1 kHz to 100 kHz in an environment of a temperature of 20 ° C. and a relative humidity of 50% RH is defined as tan δ _max. When the value is tan δ _min , the following formula (1) is satisfied. The dielectric loss tangent tan δ can be measured by the method described in the examples.

  The toner of the present invention that satisfies the above formula (1) has a small frequency dependency of tan δ. Therefore, even when electric fields of various frequencies are applied, the toner of the present invention can stably retain electric charge, respond faithfully in the development process and the transfer process, and ensure low-temperature fixability. However, high image quality can be realized.

When tan δ _max −tan δ _min exceeds 0.0035, the frequency dependency of tan δ increases and the image quality (granularity) deteriorates. tan δ _max −tan δ _min is preferably 0.0025 or less, and more preferably 0.0010 or less. The lower limit value of tan δ _max −tan δ _min is normally 0.

According to a preferred embodiment of the present invention, the dielectric loss tangent tan δ _{100 kHz} measured at a toner frequency of 100 kHz satisfies the following formula (2). Within such a range, the charge hardly leaks and the chargeability of the toner is improved.

The dielectric loss tangent tan δ _{100 kHz} is more preferably 0.027 or less, and further preferably 0.020 or less. The lower limit of tan δ _{100 kHz} is normally 0.

According to a further preferred aspect of the present invention, the frequency indicating the tan δ _max and the frequency indicating the tan δ _min satisfy the following expression (3). The toner satisfying the formula (3) is excellent in charging property, has good charging uniformity, and improves image quality (granularity). The detailed reason why such an effect can be obtained is unknown, but it is presumed that the tan δ in a higher frequency region is lowered, whereby the charge is less likely to leak and the chargeability is improved.

  The toner of the present invention satisfying the above formulas (1) and (2) is obtained by appropriately adjusting, for example, the addition amount of carbon black, the type and addition amount of monomers constituting the binder resin, and the like. be able to. For example, by using a monomer having a carboxyl group such as methacrylic acid as a monomer constituting the binder resin, it becomes easy to control the dispersion state of mainly carbon black in the toner base particles, It becomes easier to obtain a toner that satisfies the above formulas (1) and (2).

  As the amount of carbon black or crystalline resin increases, tan δ increases. Therefore, it is desirable to control the dispersibility of carbon black or crystalline resin. If the dispersibility of these components is good and the dispersion diameter is small, the conductivity inside the toner is suppressed and the chargeability is improved. The toner conductivity is considered to be mainly ionic conduction and electronic conduction, and carbon black is presumed to be related to ε ″ in a high frequency range (about 100 kHz) due to electronic conduction because free electrons exist. Further, when the binder resin contains a carboxyl group, it is presumed that the hydrogen ion derived from the carboxyl group is related to ε ″ in the low frequency region (about 1000 Hz) by ionic conduction. It is considered that the frequency dependency of tan δ changes with these balances, and it is considered that the toner of the present invention can be easily obtained by using a monomer having a carboxyl group for the binder resin.

  As an example, when a monomer having a carboxyl group is used as the monomer constituting the vinyl resin that is a constituent component of the amorphous resin, the amount of the monomer having a carboxyl group in the vinyl resin is 7 -14 mass% is preferable. The dispersibility of carbon black, charging stability, and dielectric loss tangent tan δ are considered to be correlated. With such a use amount, the dispersibility of carbon black can be improved, and the value of dielectric loss tangent tan δ Is kept low, and the toner has higher charging stability and excellent durability.

  Further, the toner satisfying the above formula (3) can be obtained by adjusting the amount of the aggregation terminator used at the time of producing the toner by the emulsion aggregation method, for example.

[CV value]
In the present invention, the coefficient of variation (CV value, hereinafter simply referred to as “CV value”) in the volume-based particle size distribution of the toner base particles is 16 to 19%. The CV value represents the degree of dispersion in the particle size distribution of the toner base particles on a volume basis, and is represented by the following formula (5). The smaller the CV value, the sharper the particle size distribution, indicating that the toner base particles have the same size.

  When the CV value is less than 16%, the toner base particles are too large in size, and the cleaning properties are deteriorated. On the other hand, when the CV value exceeds 19%, the graininess (GI value) decreases. The CV value is preferably 17 to 18%.

  This CV value can be controlled, for example, by adjusting the amount of the aggregation terminator used in the production of the toner. The volume-based median diameter and CV value of the toner base particles can be measured by “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.).

(Method for producing toner for developing electrostatic image)
Next, a method for producing the toner of the present invention will be described. The production method of the toner base particles of the present invention is not particularly limited, and examples thereof include known methods such as a kneading and pulverizing method, a suspension polymerization method, an emulsion aggregation method, a dissolution suspension method, a polyester elongation method, and a dispersion polymerization method.

  Among these, the emulsion aggregation method is preferable. By adopting the emulsion aggregation method, it is possible to obtain toner particles having a sharp particle size distribution by reducing the particle size of the toner base particles and suppressing the generation of fine powder components. In addition, there is an advantage that less energy is required during production.

  In toner production by the emulsion aggregation method, the particle size is grown using a plurality of types of particles (coloring agent, binder resin, release agent, etc.) having different particle surface properties, that is, aggregation stability.

  The emulsion aggregation method includes a dispersion of binder resin particles (a crystalline resin particle dispersion and an amorphous resin particle dispersion) containing a binder resin produced by emulsion polymerization, and a colorant (carbon black) particle. The dispersion liquid of the components constituting the toner base particles is mixed in an aqueous environment, and these are aggregated by adding an aggregating agent, and if necessary, an aggregation terminator is added to control the particle size, Further, it is a method of manufacturing toner base particles by controlling the shape by fusing between binder resin particles.

  In the emulsion aggregation method, as described above, first, binder resin particles are formed by conventionally known emulsion polymerization, and the toner particles are aggregated and fused to form toner base particles. More specifically, a monomer resin constituting the binder resin is charged into an aqueous medium, dispersed, and these polymerizable monomers are polymerized with a polymerization initiator to produce a dispersion of binder resin particles. To do.

  As a method for obtaining a crystalline resin particle dispersion, in addition to the method of polymerizing a polymerizable monomer with a polymerization initiator in the above aqueous medium, for example, a dispersion treatment is performed in an aqueous medium without using a solvent. And a method of dissolving the crystalline resin in a solvent such as ethyl acetate to form a solution, emulsifying and dispersing the solution in an aqueous medium using a disperser, and then performing a solvent removal treatment.

  At this time, if necessary, the binder resin (crystalline resin or amorphous resin) may contain a release agent in advance. For dispersion, it is also preferable to carry out polymerization in the presence of a known surfactant (for example, an anionic surfactant such as sodium polyoxyethylene (2) dodecyl ether sulfate or sodium dodecyl sulfate).

  The particle diameter (volume-based median diameter) of the binder resin particles is preferably 100 to 300 nm. The polymerization of the monomer is performed in a plurality of stages. For example, the amorphous resin is composed of two or more layers made of resins having different compositions (or resins having the same composition). It is also preferable that By using a multi-layer form in this way, a toner having a sharper particle size distribution can be obtained when the toner is produced by an emulsion aggregation method.

  Separately, colorant (carbon black) particles are dispersed in an aqueous medium to prepare a colorant particle dispersion. The particle diameter (volume-based median diameter) of the colorant particles in the dispersion is preferably 80 to 200 nm.

  Next, the binder resin particles and the colorant particles described above are aggregated in an aqueous medium, and these particles are fused to produce toner base particles. That is, after adding an alkali metal salt, an alkaline earth (Group 2) metal salt, or the like as an aggregating agent to an aqueous medium in which the binder resin particle dispersion and the colorant particle dispersion are mixed, Aggregation is advanced by heating at a temperature equal to or higher than the glass transition temperature of the binder resin particles to fuse the resin particles together. When the size of the toner base particles reaches a target size, salt is added to stop aggregation. Thereafter, the reaction system is heat-treated so that the toner base particles are aged until the shape of the toner base particles becomes a desired shape, thereby completing the toner base particles.

  Furthermore, after the dispersion liquid for aggregation reaches a temperature equal to or higher than the glass transition temperature, the fusion is continued by maintaining the temperature of the dispersion liquid for a certain period of time. Thereby, the growth of the toner base particles (aggregation of the binder resin particles and the colorant particles) and the fusion (disappearance of the interface between the particles) can be effectively advanced.

  The amount of the flocculant used is preferably 5 to 20% by mass with respect to the total solid content of the binder resin particles and the colorant particles. Thereafter, the mixture is allowed to stand for 1 to 6 minutes, and heated to 70 to 95 ° C. over 30 to 90 minutes, so that the aggregated binder resin particles and colorant particles can be fused. At this time, when the volume-based median diameter of the fused toner base particles is measured and becomes 4.5 to 10 μm, the growth of the particles is stopped by adding an aqueous solution of an aggregation stopper.

  Further, as the aging treatment, the liquid temperature is set to 70 to 90 ° C., the mixture is heated and stirred for 0.5 to 6 hours, and the average circularity is usually 0.91 or more, preferably 0.920 to 0.995. It is advisable to proceed with the fusion.

  The median diameter can be measured by, for example, Coulter Multisizer 3 manufactured by Beckman Coulter Inc. The average circularity can be measured by the method used in Examples described later. In the aging step, by applying heat and stirring shear to the toner particles, the resin particles in the aggregated particles can be fused together, and the average circularity and surface properties of the particles can be controlled.

<Aqueous medium>
In the present invention, the “aqueous medium” refers to a medium containing at least 50% by mass of water, and examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol. , Butanol, acetone, methyl ethyl ketone, dimethylformamide, methyl cellosolve, tetrahydrofuran and the like.

<Flocculant>
The aggregating agent used in the agglomerated particle forming step is not particularly limited, but a material selected from metal salts is preferred as a particle that grows by charge neutralization reaction and crosslinking action. Examples of the metal salt include monovalent metal salts such as alkali metal salts such as sodium, potassium and lithium; divalent metal salts such as calcium, magnesium, manganese and copper; and trivalent metal salts such as iron and aluminum. Etc. Specific metal salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, aluminum sulfate, polyaluminum chloride, and zinc acetate. Of these, it is particularly preferable to use a divalent metal salt because aggregation can be carried out in a smaller amount. These can be used individually by 1 type or in combination of 2 or more types.

<Aggregation stop agent>
As the aggregation terminator for stopping the growth of the agglomerated particles, a compound or salt that alleviates the aggregating action is used. For example, potassium chloride, polyvalent organic acid or a salt thereof, or amino acid, polyphosphonic acid or a salt thereof can be used. Moreover, the method of relieving the aggregation action by changing the pH in the system can also be used. In order to adjust the pH, a sodium fumarate aqueous solution, a sodium hydroxide aqueous solution, hydrochloric acid or the like can be used. Furthermore, it is also effective to adjust the pH and use a chelating agent in combination to alleviate the crosslinking action caused by metal ions. Examples of the chelating agent include HIDA (hydroxyethyliminodiacetic acid), HEDTA (hydroxyethylethylenediaminetriacetic acid), HEDP (hydroxyethylidene diphosphonic acid), and HIDS (3-hydroxy-2,2′-iminodisuccinic acid).

  As described above, the CV value of the toner of the present invention can be controlled by the addition amount of the aggregation terminator. Generally, the CV value decreases as the addition amount of the aggregation terminator increases, and the CV value increases as the amount of the aggregation terminator decreases. For example, when potassium chloride is used as the aggregation terminator, the addition amount is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, based on the total solid content of the toner base particles. preferable.

  As mentioned above, according to one form of the manufacturing method of the electrostatic image developing toner, the following steps are included.

(1) Colorant particle dispersion liquid preparation step for preparing a dispersion liquid in which colorant (carbon black) particles are dispersed in an aqueous medium. (2) A release agent and a charge control agent in the aqueous medium as necessary. Binder resin particle dispersion liquid preparation step for preparing a dispersion liquid in which binder resin particles (crystalline resin particles, amorphous resin particles) are dispersed, containing an internal additive such as (3) Binder resin Aggregation and fusing step of agglomerating and fusing particles, colorant particles, and if necessary, other toner constituent particles in an aqueous medium to grow the aggregated particles (4) Specific in the aqueous medium Aggregation terminator addition step of stopping aggregation by adding an aggregation terminator to stop the aggregation particle growth (5) Including a ripening step of aging the aggregated particles with thermal energy to control the shape and obtaining toner base particles .

  In addition, according to a preferred embodiment of the method for producing a toner for developing an electrostatic charge image, the following steps are further included.

(6) Filtration and washing step of removing toner base particles from the aqueous medium and removing the aggregating agent, aggregation terminator, surfactant and the like from the toner base particles. (7) Drying the toner base particles subjected to the cleaning treatment. Drying process
(8) An electrostatic charge image developing toner can be produced through an external additive addition step of adding an external additive to the dried toner base particles.

[Developer]
The toner of the present invention may be used, for example, as a one-component magnetic toner containing a magnetic material, as a two-component developer mixed with a so-called carrier, or as a non-magnetic toner alone. Any of these can be suitably used.

  As the carrier constituting the two-component developer, magnetic particles made of conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. It is preferable to use ferrite particles.

  The carrier preferably has a volume average particle diameter of 15 to 100 μm, more preferably 25 to 60 μm.

  As the carrier, it is preferable to use a carrier further coated with a resin or a so-called resin dispersion type carrier in which magnetic particles are dispersed in the resin. The resin composition for coating is not particularly limited, and for example, olefin resin, cyclohexyl methacrylate-methyl methacrylate copolymer, styrene resin, styrene acrylic resin, silicone resin, ester resin, or fluorine resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and known resins can be used. For example, acrylic resin, styrene acrylic resin, polyester resin, fluorine resin, phenol resin, etc. can be used. Can do.

  Hereinafter, representative embodiments of the present invention will be shown and the present invention will be further described, but the present invention is of course not limited to these embodiments. In the examples, unless otherwise specified, “part” represents “part by mass” and “%” represents “% by mass”.

[Production of toner]
<Example 1>
[Preparation of Dispersion Liquid [MD1] of Amorphous Resin (Vinyl Resin) Particles [M1] Containing Release Agent]
(First stage polymerization)
A 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introducing device was charged with a solution prepared by dissolving 8 g of sodium dodecyl sulfate in 3 L of ion-exchanged water, and stirred at a stirring speed of 230 rpm under a nitrogen stream. After raising the internal temperature to 80 ° C., a solution in which 10 g of potassium persulfate was dissolved in 200 g of ion-exchanged water was added, and the liquid temperature was again adjusted to 80 ° C.
Styrene 480g
n-Butyl acrylate 250g
Methacrylic acid 68g
After the monomer mixed liquid consisting of 1 was added dropwise over 1 hour, polymerization was performed by heating and stirring at 80 ° C. for 2 hours to prepare a resin particle dispersion [A1] in which the resin particles [a1] were dispersed. .

(Second stage polymerization)
A 5 L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device was charged with a solution of 6 g of polyoxyethylene (2) sodium dodecyl ether sulfate in 1850 ml of ion-exchanged water and heated to 80 ° C. 260 g of the above resin particle dispersion [A1] was added.

175 g of styrene
n-Butyl acrylate 80g
n-octyl-3-mercaptopropionate 3.8 g
Mold release agent: 86.5 g behenyl behenate (melting point 73 ° C.)
Is mixed and dispersed for 15 minutes with a mechanical disperser “CLEAMIX (registered trademark)” (manufactured by M Technique Co., Ltd.) having a circulation path. A dispersion liquid containing oil droplets) was prepared.

  Next, an initiator solution prepared by dissolving 5 g of potassium persulfate in 100 ml of ion-exchanged water is added to the reaction vessel, and the system is polymerized by heating and stirring at 82 ° C. for 1 hour to obtain resin particles [a2]. A dispersed resin particle dispersion [A2] was prepared.

(3rd stage polymerization)
To the above resin particle dispersion [A2], a solution in which 5 g of potassium persulfate is dissolved in 100 ml of ion-exchanged water is added.
Styrene 303.5g
n-Butyl acrylate 118.5g
Methacrylic acid 70g
n-octyl-3-mercaptopropionate 8 g
A monomer mixture consisting of was added dropwise over 90 minutes. After completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, followed by cooling to 28 ° C., whereby amorphous resin particles [M1] containing a vinyl monomer as a main component and containing a release agent. A dispersion [MD1] was prepared.

  With respect to this dispersion [MD1], the volume-based median diameter of the amorphous resin particles [M1] was measured and found to be 230 nm. Moreover, when the molecular weight of the amorphous resin which comprises the said amorphous resin particle [M1] was measured, the weight average molecular weight was 30,200.

[Preparation of aqueous dispersion [C1] of hybrid crystalline polyester resin particles]
Synthesis of Hybrid Crystalline Polyester Resin (c1) A raw material monomer (monomer), an amphoteric monomer (monomer) of the following addition polymerization resin, and a radical polymerization initiator were placed in a dropping funnel.

Styrene 35 parts by mass n-butyl acrylate 9 parts by mass Acrylic acid 4 parts by mass Polymerization initiator (di-t-butyl peroxide) 7 parts by mass Furthermore, the following polycondensation-type raw material monomers are introduced into a nitrogen introduction tube, a dehydration tube, and stirring. A four-necked flask equipped with a vessel and a thermocouple was heated to 170 ° C. to dissolve.

318 parts by weight of dodecanedioic acid 196 parts by weight of 1,6-hexanediol Next, the raw material monomer of the addition polymerization resin was added dropwise over 90 minutes with stirring, and after aging for 60 minutes, under reduced pressure (8 kPa) Unreacted addition polymerization monomer was removed. Thereafter, 0.8 parts by mass of Ti (On-Bu) ₄ was added as an esterification catalyst, heated to 235 ° C., under normal pressure (101.3 kPa) for 5 hours, and further under reduced pressure (8 kPa). The reaction was carried out for 1 hour. Next, after cooling to 200 ° C., a hybrid crystalline polyester resin (c1) was obtained by reacting under reduced pressure (20 kPa) for 1 hour. The obtained hybrid crystalline polyester resin (c1) had a weight average molecular weight (Mw) of 8,100 and a melting point of 79 ° C.

30 parts by mass of the hybrid crystalline polyester resin (c1) was transferred in a molten state at a transfer rate of 100 parts by mass per minute to the emulsifier-dispersing machine “Cavitron CD1010” (manufactured by Eurotech Co., Ltd.). Simultaneously with the transfer of the hybrid crystalline polyester resin (c1) in the molten state, 70 mass parts of reagent ammonia water was diluted with ion-exchanged water in an aqueous solvent tank with respect to the emulsifying disperser, and the concentration was 0.37 mass. % Dilute aqueous ammonia was transferred at a transfer rate of 0.1 liter per minute while heating to 100 ° C. with a heat exchanger. And by operating this emulsification disperser under the conditions of a rotor rotational speed of 60 Hz and a pressure of 5 kg / cm ² , the volume-based median diameter of 200 nm and the solid crystalline content of the hybrid crystalline polyester resin particles having a solid content of 30% by mass are obtained. An aqueous dispersion [C1] (crystalline resin particle dispersion [C1]) was prepared.

[Preparation of Colorant (Carbon Black) Particle Dispersion [Bk]]
While stirring and dissolving 90 g of sodium dodecyl sulfate in 1600 g of ion-exchanged water, 420 g of carbon black (Furness Black) “Regal (registered trademark) 330R” (manufactured by Cabot) is gradually added, followed by stirring. A colorant particle dispersion [Bk] in which the colorant particles [Bk] are dispersed was prepared by dispersing using an apparatus “Clearmix (registered trademark)” (manufactured by M Technique Co., Ltd.). The volume-based median diameter of the colorant particles [Bk] in the colorant particle dispersion [Bk] was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.). It was.

[Toner Production Example 1]
In a flask equipped with a stirrer, temperature sensor, condenser and nitrogen inlet,
-400 parts by mass of ion exchange water,
-504 parts by mass (in terms of solid content) of a dispersion [MD1] of amorphous resin particles [M1] containing a release agent,
-Colorant (carbon black) particle dispersion [Bk] 54 parts by mass (in terms of solid content),
-Crystalline resin particle dispersion [C1] 42 parts by mass (in terms of solid content),
After adjusting the liquid temperature to 25 ° C., an aqueous sodium hydroxide solution having a concentration of 25% by mass was added to adjust the pH to 10.5.

  Next, an aqueous solution in which 50 parts by mass of magnesium chloride hexahydrate is dissolved in 50 parts by mass of ion-exchanged water is added, and the temperature of the system is raised to 80 ° C. The agglutination reaction was started. In the present invention, the order of addition of the dispersion [MD1], the colorant particle dispersion [Bk], the crystalline resin particle dispersion [C1], and magnesium chloride is not particularly limited. The same applies hereinafter.

  After the start of this agglomeration reaction, sampling is performed periodically, and the volume-based median diameter is measured using a particle size distribution measuring apparatus “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.). Aggregation was continued while stirring until the diameter reached 6.0 μm.

  Thereafter, an aqueous solution in which 120 parts by mass of potassium chloride was dissolved in 600 parts by mass of ion-exchanged water was added, the temperature of the system was set to 82 ° C., and stirring was continued for 4 hours, and a flow particle image analyzer “FPIA-2100” (Sysmex) When the average circularity reached 0.960 as measured by the company), the reaction was stopped by cooling to 30 ° C. at a cooling rate of 6 ° C./min to obtain a dispersion of toner base particles. As a result of measurement using a particle size distribution measuring apparatus “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.), the toner base particles after cooling had a particle diameter (volume-based median diameter) of 6.1 μm and a CV value of 17 %Met. The average circularity was 0.960. In other examples and comparative examples, the particle diameter and the average circularity were the same as those in Example 1.

  The thus obtained dispersion of toner base particles was subjected to solid-liquid separation using a basket-type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Machine Sales Co., Ltd.) to form a wet cake. The wet cake was repeatedly washed and solid-liquid separated with the basket-type centrifuge until the electric conductivity of the filtrate reached 15 μS / cm, and then “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.) was used. Drying was performed by blowing an air stream at a temperature of 40 ° C. and a relative humidity of 20% RH until the water content became 0.5% by mass, and then cooling to 24 ° C. gave toner base particles [1X].

  1% by mass of hydrophobic silica particles (number average secondary particle size: 30 μm, number average primary particle size: 50 to 200 nm) and hydrophobic titanium oxide particles (number average two particles) with respect to the obtained toner base particles [1X]. Secondary particle size: 20 μm, number average primary particle size: 50 to 200 nm) and 1.2 mass%, and using a Henschel mixer, mixing for 20 minutes under the condition of a peripheral speed of the rotor blades of 24 m / s, An external additive was added by passing through a 400 mesh screen to obtain toner [1].

<Example 2>
In (third stage polymerization) in [Preparation of dispersion liquid [MD1] of amorphous resin particles [M1] containing a release agent], the amount of monomer was changed as follows to change amorphous resin fine particles [M2 A toner [2] was produced in the same manner as in Example 1 except that the dispersion [MD2] was obtained. With respect to the dispersion [MD2], the volume-based median diameter of the amorphous resin particles [M2] was measured to be 222 nm. Moreover, when the molecular weight of the amorphous resin which comprises the said amorphous resin particle [M2] was measured, the weight average molecular weight (Mw) was 31,200.

318 g of styrene
114g of n-butyl acrylate
Methacrylic acid 60g
<Example 3>
In [Preparation of dispersion liquid [MD1] of amorphous resin particles [M1] containing a release agent] (third-stage polymerization), the amount of monomer was changed as follows to change amorphous resin particles [M3 A toner [3] was produced in the same manner as in Example 1 except that the dispersion [MD3] was obtained. With respect to the dispersion [MD3], the volume-based median diameter of the amorphous resin particles [M3] was measured and found to be 234 nm. Moreover, when the molecular weight of the amorphous resin which comprises the said amorphous resin particle [M3] was measured, the weight average molecular weight (Mw) was 30,800.

Styrene 351.75 g
n-Butyl acrylate 105.25g
Methacrylic acid 35g
<Example 4>
Implementation was performed except that, in [Toner Production Example 1], the amount of the dispersion [MD1] was 468 parts by mass (in terms of solids) and the amount of the dispersion [Bk] was 90 parts by mass (in terms of solids). In the same manner as in Example 1, a toner [4] was produced.

<Example 5>
Implementation was performed except that, in [Toner Production Example 1], the amount of the dispersion [MD1] was 522 parts by mass (in terms of solid content) and the amount of the dispersion [Bk] was 36 parts by mass (in terms of solid content). In the same manner as in Example 1, a toner [5] was produced.

<Example 6>
A toner [6] was produced in the same manner as in Example 1, except that 240 parts by mass of potassium chloride used for stopping the agglutination reaction was dissolved in 1200 parts by mass of ion-exchanged water.

<Example 7>
A toner [7] was produced in the same manner as in Example 1, except that 60 parts by mass of potassium chloride used for stopping the agglutination reaction was dissolved in 300 parts by mass of ion-exchanged water.

<Comparative Example 1>
In [3rd stage polymerization] in [Preparation of dispersion liquid [MD1] of amorphous resin particles [M1] containing a release agent], the amount of monomers was changed as follows to change amorphous resin particles [M4 A toner [8] was produced in the same manner as in Example 1 except that the dispersion [MD4] was obtained. With respect to the dispersion [MD4], the volume-based median diameter of the amorphous resin particles [M4] was measured and found to be 230 nm. Moreover, when the molecular weight of the amorphous resin which comprises the said amorphous resin particle [M4] was measured, the weight average molecular weight (Mw) was 31,000.

359 g of styrene
n-Butyl acrylate 103g
Methacrylic acid 30g
<Comparative example 2>
Implementation was performed except that, in [Toner Production Example 1], the amount of the dispersion [MD1] was 462 parts by mass (in terms of solid content) and the amount of the dispersion [Bk] was 96 parts by mass (in terms of solid content). In the same manner as in Example 1, a toner [9] was produced.

<Comparative Example 3>
Implementation was performed except that, in [Toner Production Example 1], the amount of the dispersion [MD1] was 528 parts by mass (in terms of solid content) and the amount of the dispersion [Bk] was 30 parts by mass (in terms of solid content). In the same manner as in Example 1, a toner [10] was produced.

<Comparative Example 4>
In [Toner Production Example 1], the amount of the dispersion [MD1] was changed to 546 parts by mass (in terms of solid content), and the crystalline resin particle dispersion [C1] was not used. Thus, toner [11] was produced.

<Comparative Example 5>
A toner [12] was produced in the same manner as in Example 1 except that the amount of potassium chloride used for stopping the agglutination reaction was 50 parts by mass.

<Comparative Example 6>
A toner [13] was produced in the same manner as in Example 1 except that the amount of potassium chloride used for stopping the agglutination reaction was 360 parts by mass.

[Developer preparation]
Each of the produced toners 1 to 13 was mixed with a ferrite carrier coated with a silicone resin and having a volume average particle diameter of 60 μm to prepare a developer for each toner. The toner concentration in each developer was adjusted to 7.5% by mass.

[Performance evaluation]
<Dielectric loss tangent (tan δ)>
As a measurement sample, a disk-shaped sample (thickness: about 2 mm) of 40 mmφ obtained by molding ² g of toner and applying a load of 100 kgf / cm ² over 10 seconds was used. In addition, the thickness of each disk-shaped sample was measured with calipers. The dielectric loss tangent tan δ was measured using an LCR meter 65120P (manufactured by Toyo Corporation) under an environment of a temperature of 20 ° C. and a relative humidity of 50% RH. Use the included software WITNESS-6000, set the measurement frequency from 1 kHz to 100 kHz, set the number of single-digit points to 5, and set the number of averaging to 3, and input the thickness of the disk-shaped sample. Went.

<Granularity (GI value)>
Using a commercially available composite printer “bizhub PRO (registered trademark) C500” (manufactured by Konica Minolta Co., Ltd.), a gradation pattern with a gradation ratio of 32 steps is output, and the granularity of this gradation pattern is in accordance with the following evaluation criteria. evaluated. Graininess is evaluated by applying a Fourier transform process considering MTF (Modulation Transfer Function) correction to the reading value of the gradation pattern CCD, and measuring the GI value (Graininess Index) according to the human specific visual sensitivity. The GI value was determined. The smaller the GI value, the better. In addition, this GI value is a value published in Journal of the Imaging Society of Japan 39 (2), 84/93 (2000). In this evaluation, if the GI value was 0.21 or less, it was determined to be acceptable.

<Image density>
A commercially available composite printer “bizhub PRO (registered trademark) C500” (manufactured by Konica Minolta Co., Ltd.) was modified and output on CF paper manufactured by Konica Minolta Co., Ltd. in an environment of a temperature of 20 ° C. and a relative humidity of 50% RH. . By adjusting the developing bias, the toner adhesion amount on the paper surface was adjusted to 4.5 g / m ² and the image density was measured.

  For the image density, a spectrophotometer “Gretag Macbeth Spectrolino” (manufactured by Gretag Macbeth) was used, a D65 light source as a light source, a φ4 mm reflection measurement aperture, a measurement wavelength region of 380 to 730 nm at 10 nm intervals, and a viewing angle. The angle was set to 2 °, and the measurement was performed under conditions using a dedicated white tile for reference alignment. In this evaluation, an image density of 1.80 or more was considered acceptable.

<Charge amount>
Place the developer between the parallel plate (aluminum) electrodes while sliding, and develop the toner under the conditions of a gap between electrodes of 0.5 mm, DC bias of 1.0 kV, AC bias of 4.0 kV, and 2.0 kHz. The charge amount and the mass of the toner were measured, and the charge amount per unit mass Q / m (μC / g) was defined as the charge amount. In this evaluation, 45 μC / g or more was regarded as acceptable.

<Under offset temperature (low temperature fixability)>
As the image forming apparatus, a commercially available full-color multifunction peripheral “bizhub PRO (registered trademark) C6500” (manufactured by Konica Minolta Co., Ltd.) modified so that the surface temperatures of the upper fixing belt and the lower fixing roller can be changed was used. A solid image with a toner adhesion amount of 11.3 g / m ² is output at a fixing temperature of 200 ° C. and a fixing speed of 300 mm / sec on a recording material “NPi fine paper 128 g / m ² ” (manufactured by Nippon Paper Industries Co., Ltd.). The test was repeated until the cold offset occurred while changing the fixing temperature in steps of 5 ° C. The minimum surface temperature of the upper fixing belt where no cold offset occurred was investigated, and this was determined as the lower limit fixing temperature. As a result, the low-temperature fixability was evaluated. In each test, the fixing temperature is the surface temperature of the upper fixing belt, and the surface temperature of the lower fixing roller is always set to a temperature 20 ° C. lower than the upper fixing belt. The lower the fixing minimum temperature, the better the low-temperature fixing property. In this evaluation, the case where the temperature was less than 145 ° C. was regarded as acceptable.

<Cleanability>
Using a modified machine of the image forming apparatus “bizhub PRO (registered trademark) C6500” (printing speed of about 65 sheets / min) (manufactured by Konica Minolta Co., Ltd.) on a photoconductor in a low temperature and low humidity environment (10 ° C., 15% RH) The bias voltage was set so that the toner adhesion amount was 4 g / m ² , and the primary transfer current value was 0 μA. Thereafter, high-quality paper (65 g / m ² ) of A3 plate was poured, the presence or absence of slipping of the image was visually confirmed, and the number of prints when slipping occurred was evaluated as the cleaning property. A case where the number of printed sheets was 5 or more was regarded as acceptable.

  The configurations and evaluation results of the toners of the examples and comparative examples are shown in Table 1 below. In Table 1, “MAA amount” is the content of methacrylic acid in the vinyl resin, “CB amount” is the content of carbon black in the toner base particles, and “CPES amount” is the hybrid in the toner base particles. The content of the crystalline polyester resin is expressed respectively.

  As apparent from Table 1 above, it can be seen that the toners of all the examples have improved chargeability, can realize high image quality, and are excellent in cleaning properties and low-temperature fixability.

On the other hand, the toners of Comparative Examples 1 and 2 have a large difference between tan δ _max and tan δ _min , suggesting that the image quality deteriorates. The toner of Comparative Example 3 had a low carbon black content and a insufficient concentration. The toner of Comparative Example 4 did not contain a crystalline resin, and the low-temperature fixability was lowered. The toner of Comparative Example 5 had a high CV value and decreased graininess. The toner of Comparative Example 6 had a low CV value and a poor cleaning property.

Claims (5)

A toner for developing an electrostatic image comprising a binder resin containing a crystalline resin, a release agent, and toner base particles having at least carbon black,
The carbon black content in the toner base particles is 6 to 15% by mass,
The coefficient of variation (CV value) in the volume-based particle size distribution of the toner base particles is 16 to 19%,
When the maximum value of the dielectric tangent tan δ obtained by measuring in the frequency range from 1 kHz to 100 kHz in the environment of a temperature of 20 ° C. and a relative humidity of 50% RH is tan δ _max and the minimum value is tan δ _min , the following formula ( An electrostatic charge image developing toner satisfying 1).
  The electrostatic image developing toner according to claim 1, wherein the crystalline resin is a crystalline polyester resin. The electrostatic charge image developing toner according to claim 1, wherein a dielectric loss tangent tan δ of _{100 kHz} measured at a frequency of 100 kHz satisfies the following formula (2).
The electrostatic image developing toner according to claim 1, wherein the dielectric loss tangent tan δ satisfies the following formula (3).
  The electrostatic image developing toner according to claim 1, wherein the binder resin further contains a vinyl resin.