JP2005274964A - Toner for electrophotography, and method for manufacturing the same, and developer for electrophotography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for electrophotography for which low temperature fixation is possible, of which an image fixed at low temperature has high glossiness and of which the cleaning property is excellent without damaging the transfer property, a developer, and a method for manufacturing the toner. <P>SOLUTION: The toner for electrophotography includes a binder resin and a colorant and has a core shell structure and is characterized by comprising the core mainly including a crystalline resin, having the ratio of the shell to the core to be 15 mass % or more and 120 mass % or less, comprising the shell with a hemispherical protrusion of which the elevation change is 0.3 μm or more and having the shell fabricated with emulsification coagulation method. The developer includes the toner and a carrier. The method for manufacturing the toner for electrophotography described in the claim 1 comprises mixing a fine particle dispersion of a shell forming resin into a core dispersion containing the binder resin in which the main component is the crystalline resin and the colorant and coagulating and adhering the fine particles of the shell forming resin to the core surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic toner used for developing an electrostatic latent image formed by an electrophotographic method or an electrostatic recording method, a manufacturing method thereof, and an electrophotographic developer.

  Methods for visualizing image information through an electrostatic latent image, such as electrophotography, are currently used in various fields. In electrophotography, an electrostatic image is formed on a photoreceptor by a charging / exposure process, developed with a developer containing toner, and then visualized through a toner image transfer and fixing process. The developer used here includes a two-component developer composed of a toner and a carrier, and a one-component developer using a magnetic toner or a non-magnetic toner alone. The method for producing the toner is usually a thermoplastic resin. A kneading and pulverizing method is used, in which melt is kneaded together with a release agent such as a pigment, a charge control agent, and wax, cooled, finely pulverized, and further classified. The formed toner is added with inorganic or organic fine particles for improving fluidity and cleaning properties as required, and is adhered to the surface of the toner particles.

  In ordinary kneading and pulverization methods, the toner shape and the surface structure of the toner are indefinite, although it varies slightly depending on the pulverization properties of the materials used and the conditions of the pulverization process. is there. In particular, in the case of a toner using a material having a high pulverization property, generation of fine powder or a change in toner shape is often caused by mechanical force in a developing machine. Due to these effects, in the two-component developer, the charging deterioration of the developer is accelerated due to adhesion of fine powder to the carrier surface, and in the one-component developer, toner scattering occurs due to the expansion of the particle size distribution, and the toner shape Deterioration in image quality is likely to occur due to a decrease in developability due to a change in the image quality. When a toner such as wax is internally added to form a toner, depending on the combination with a thermoplastic resin, the release agent is often exposed on the surface and various effects are caused during development. The irregular shaped toner is advantageous in terms of cleaning property, which removes untransferred toner from the photoreceptor, and the surface wax is easily transferred by mechanical force, so that the surface of the developing roll, photoreceptor and carrier Contamination is likely to occur, leading to reduced reliability.

On the other hand, in recent years, toner produced by a wet manufacturing method has been used. In the wet manufacturing method, the toner generally tends to be spherical. A characteristic of the spherical toner is high transfer efficiency. In addition, it is possible to encapsulate the release agent and prevent the release agent from being exposed on the surface of the toner, and the generation of fine powder in the developing machine is small, which is advantageous for surface contamination of the developing roll, photoreceptor and carrier. . However, in the case of blade cleaning, because of the spherical shape, the toner passes under the cleaning blade, resulting in poor cleaning performance.
Further, an EA (emulsion aggregation method) method is known as a wet toner manufacturing method that is amorphous and includes a release agent. In this method, latex fine particles of 1 micron or less are aggregated to produce aggregated particles having a toner diameter, and then the aggregated particles are combined to form a toner. In this coalescence process, the latex agglomerated toner is finally coalesced into a spherical shape, but the toner can be taken out as an irregular toner during the coalescence process. Since the toner produced by this production method is closer to a spherical shape than the kneaded and pulverized toner, the transfer efficiency is generally better than that of the kneaded and pulverized toner. By using this EA manufacturing method, an irregular toner containing a release agent can be obtained, and a toner having both a cleaning property and a transfer property can be obtained. However, in this EA method, it is difficult to make the toner amorphous when the latex has a low melt viscosity.

On the other hand, a toner having a capsule structure has been proposed as a pressure toner or a low-temperature fixing toner. Since the capsule structure is generally made by a wet manufacturing method, the shape is spherical, and a release agent or the like can be included in the core.
However, in order to improve the blade cleaning property, it is desirable to make the toner shape of the capsule structure (core shell structure) indefinite. In order to make the shape of the capsule structure toner indefinite, the spherical core can be realized by encapsulating the spherical core with a capsule having an uneven surface, and is an effective method. Several methods for this have already been proposed.
As a method for making the shape of the capsule surface uneven, Patent Document 1 below discloses a toner in which shell particles are buried in a core shallower than the particle diameter of the shell particle to make the surface shape uneven. It is disclosed. In Patent Document 2 below, resin fine particles are fixedly coated on the base particles by mechanical impact force, and the specific area of the particles (toner) after the fixed coating is -0.3 to 0.1 m ² / g with respect to the base particles. Toners with varying degrees are disclosed. Although the degree of unevenness of the core-shell structure toners in Patent Documents 1 and 2 is different, since the surface layer is formed by mechanical force, the shell layer is easily peeled off, resulting in a developer having a short life.

Further, Patent Document 3 below has a microcapsule form composed of a core material composed of a fixing component and a colorant and an outer shell covering the periphery of the core material, and the outer shell has a hemispherical protrusion structure ( A capsule toner having a diameter of 0.01 to 2 μm and a height of 0.001 to 2 μm on the entire surface is described. This capsule toner is particularly suitable for pressure fixing, and the fixing component is a liquid (resin and organic solvent) that easily flows out of the capsule and adheres to paper or the like when the capsule collapses due to pressure. . In this capsule toner, after preparing a capsule containing the fixing component and the colorant as described above, a monomer for forming an uneven shell (outer shell) is added to the capsule dispersion, and a polymerization reaction is carried out in water, thereby It is produced by forming a projection structure as described above on the surface of the shell. This toner is considered to be difficult to peel off because the shell and the core are chemically bonded, and may have a long life. However, the microcapsule toner disclosed in Patent Document 3 further increases the number of processes because it further forms irregularities on the capsule structure. Therefore, if irregularities are provided when the capsule structure is manufactured, the process can be simplified. Further, the toner produced by this method has a fixing component in a liquid state and is used for pressure fixing, and unlike a heat fixing toner, a hard shell is required. Therefore, it is not a high gloss toner.
JP 63-131149 A JP-A-2-208661 JP-A-3-228066

  The present invention has been made in view of the above-described problems, and an object of the present invention is to enable low-temperature fixing, a low-temperature-fixed image has high gloss, and cleaning properties without impairing transferability. It is an object of the present invention to provide a toner and a developer for electrophotography with good and a method for producing the toner.

The above problems can be solved by providing the following electrophotographic toner, a method for producing the same, and a developer for electrophotography.
(1) An electrophotographic toner containing a binder resin and a colorant and having a core-shell structure, wherein the core mainly contains a crystalline resin, and the shell is 15% by mass or more and 120% by mass or less with respect to the core. An electrophotographic toner, wherein the shell has hemispherical protrusions having a step of 0.3 μm or more, and the shell is produced by an emulsion aggregation method.
(2) A fine particle dispersion of a shell-forming resin is mixed with a core dispersion containing a binder resin mainly composed of a crystalline resin and a colorant, and the fine particles of the shell-forming resin are adhered and aggregated on the core surface. The method for producing an electrophotographic toner according to claim 1.
(3) An electrophotographic developer containing a toner and a carrier, wherein the toner contains a binder resin and a colorant, the core mainly contains a crystalline resin, and the shell is 15% by mass with respect to the core. An electrophotographic developer, wherein the developer is 120% by mass or less, the shell has hemispherical protrusions having a step of 0.3 μm or more, and the shell is produced by an emulsion aggregation method.

Since the core-shell structured toner of the present invention contains a crystalline resin in the core and is coated with a shell having protrusions on the surface of the toner particles, it is excellent in low-temperature fixability, and the image fixed at low temperature exhibits high gloss. In addition, the developer using the toner of the present invention has good cleaning properties without impairing transfer properties. Therefore, photoconductor filming can also be prevented, and high-quality images can be stably obtained over a long period of time. Furthermore, since fixing at a low temperature is possible, power consumption can be reduced and the environmental load can be reduced.
In addition, since the shell of the toner of the present invention is produced by an emulsion aggregation method, the shell layer is difficult to peel off and is excellent in durability. Further, since the surface adhesion of a release agent or the like is small, toner blocking resistance is also excellent.

The electrophotographic toner of the present invention (hereinafter sometimes simply referred to as “toner”), a method for producing the same, and an electrophotographic developer (hereinafter sometimes simply referred to as “developer”) will be described below. To do.
[Electrophotographic toner]
The toner of the present invention has a core-shell structure, the core mainly contains a crystalline resin, the shell has hemispherical protrusions of 15% by mass to 120% by mass and a step of 0.3 μm or more. Further, the shell is formed by an emulsion aggregation method. Here, “the core mainly contains a crystalline resin” means that the crystalline resin is contained in the core in an amount of 50% by mass or more, more preferably 60% by mass or more, and more preferably 100% by mass. preferable. The “step” refers to the height of the protrusion with respect to the core surface.
Further, “the shell is formed by the emulsion aggregation method” means that a fine particle dispersion (emulsion, solid dispersion) containing components (binder resin, etc.) contained in the shell is prepared, It means forming a shell by attaching and agglomerating fine particles to the core surface.

If the ratio of the shell to the core is less than 15% by mass, the chargeability tends to be low, and if it exceeds 120% by mass, the low-temperature fixability tends to be impaired, so the above range is necessary. The range is preferably 15 to 70% by mass, more preferably 20 to 50% by mass.
On the other hand, if the level difference is smaller than 0.3 μm, the blade cleaning property and the fixing efficiency which are the problems of the present invention cannot be achieved. The step is preferably 0.35 μm or more, more preferably 0.4 μm or more. The upper limit of the step is about 1 μm.
The number of protrusions is determined by observing the toner surface (half of the toner surface) with an SEM, extracting 10 neighboring toners on the SEM image, counting the protrusions on the toner surface on the SEM image, and adding 2 to this. It is obtained by calculating the average of the multiplied numbers. It is preferable that 40 to 400, preferably 60 to 300, of the protrusions exist on the surface of the toner.

  The toner of the present invention preferably has a melt viscosity at 75 ° C. of 5000 Pas or less from the viewpoint of low-temperature fixability. The melt viscosity is more preferably 4500 PaS or less, and further preferably 4000 PaS or less. The lower limit of the melt viscosity is not particularly limited, but if it is 100 PaS or more, there is no problem of shortening the service life due to offset or toner adhering to the fixing roll and deteriorating.

  The toner of the present invention contains a binder resin and a colorant and, if necessary, other components (such as a release agent). First, the binder resin will be described.

<Binder resin>
The toner of the present invention includes a crystalline resin as a main component in the core. That is, 50% by mass or more of the core portion is occupied by the crystalline resin. By using a crystalline resin as a main component, it is possible to achieve both low-temperature fixability, toner blocking resistance and image storage stability.
In the present invention, the “crystallinity” of the “crystalline resin” refers to having a clear endothermic peak in the differential scanning calorimetry (DSC) instead of a stepwise endothermic change. Further, the endothermic peak may show a peak having a width of 40 to 50 ° C. when the toner is used.
The melting point of the crystalline resin is preferably in the range of 50 ° C. to 120 ° C., and more preferably in the range of 60 to 85 ° C.
As the crystalline resin, a crystalline polyester resin, a crystalline acrylic resin, or the like is used, and it is preferable to use a crystalline polyester resin in view of the melting point and the like.

  In the case of a polymer obtained by copolymerizing other components with the crystalline polyester main chain, if the other components are 50% by mass or less, this copolymer is also called crystalline polyester.

-Acid-derived components-
Examples of the acid for forming the acid-derived constituent component include various dicarboxylic acids. As the acid-derived constituent component in the specific polyester resin, aromatic dicarboxylic acid and aliphatic dicarboxylic acid are preferable, and aliphatic dicarboxylic acid is particularly preferable. An acid is desirable, and a linear carboxylic acid is particularly desirable.

  Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid. 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, Or lower alkyl esters and acid anhydrides thereof, but are not limited thereto. Among these, considering availability, sebacic acid and 1,10-decanedicarboxylic acid are preferable.

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid and the like. It is preferable in terms of easy formation.

As the acid-derived constituent component, in addition to the aforementioned aliphatic dicarboxylic acid-derived constituent component and aromatic dicarboxylic acid-derived constituent component, a dicarboxylic acid-derived constituent component having a double bond, a dicarboxylic acid-derived constituent component having a sulfonic acid group, etc. Are preferably included.

  The component derived from a dicarboxylic acid having a double bond is derived from a lower alkyl ester or acid anhydride of a dicarboxylic acid having a double bond, in addition to a component derived from a dicarboxylic acid having a double bond. Components are also included. The dicarboxylic acid-derived component having a sulfonic acid group is derived from a lower alkyl ester or acid anhydride of a dicarboxylic acid having a sulfonic acid group, in addition to a component derived from a dicarboxylic acid having a sulfonic acid group. Components are also included.

  The dicarboxylic acid having a double bond can be suitably used to prevent hot offset at the time of fixing since the entire resin can be crosslinked using the double bond. Examples of such dicarboxylic acids include, but are not limited to, fumaric acid, maleic acid, 3-hexenedioic acid, and 3-octenedioic acid. Moreover, these lower alkyl esters, acid anhydrides, etc. are also mentioned. Among these, fumaric acid, maleic acid and the like are preferable in terms of cost.

The dicarboxylic acid having a sulfonic acid group is effective in that it can favorably disperse a coloring material such as a pigment. Further, when the entire resin is emulsified or suspended in water to produce fine particles, if a sulfonic acid group is present, it can be emulsified or suspended without using a surfactant as described later. Examples of such a dicarboxylic acid having a sulfone group include, but are not limited to, 2-sulfoterephthalic acid sodium salt, 5-sulfoisophthalic acid sodium salt, and sulfosuccinic acid sodium salt.
Moreover, these lower alkyl esters, acid anhydrides, etc. are also mentioned. Among these, 5-sulfoisophthalic acid sodium salt is preferable in terms of cost.

All of these acid-derived components other than aliphatic dicarboxylic acid-derived components and aromatic dicarboxylic acid-derived components (dicarboxylic acid-derived components having double bonds and dicarboxylic acid-derived components having sulfonic acid groups) As content in an acid origin structural component, 1-20 structural mol% is preferable and 2-10 structural mol% is more preferable.
When the content is less than 1 component mol%, pigment dispersion is not good, the emulsion particle size becomes large, and adjustment of the toner diameter by aggregation may be difficult, whereas it exceeds 20 component mol%. In some cases, the crystallinity of the polyester resin is lowered, the melting point is lowered, the storability of the image is deteriorated, or the emulsified particle diameter is too small to be dissolved in water, thereby causing no latex.
In the present specification, “constituent mol%” refers to a percentage when each constituent component (acid-derived constituent component or alcohol-derived constituent component) in the polyester resin is defined as one unit (mol).

-Alcohol-derived components-
As alcohol for becoming a component derived from alcohol, aliphatic diol is preferable, and linear aliphatic diol having 7 to 20 chain carbon atoms is more preferable. When the aliphatic diol is branched, the crystallinity of the polyester resin is lowered and the melting point is lowered, so that the toner blocking resistance, the image storage stability, and the low-temperature fixability may be deteriorated. When the chain carbon number is less than 7, when polycondensation with an aromatic dicarboxylic acid, the melting point becomes high and low-temperature fixing may be difficult. It tends to be difficult to obtain. The chain carbon number is more preferably 14 or less.

  Further, when a polyester is obtained by condensation polymerization with an aromatic dicarboxylic acid, the chain carbon number is preferably an odd number. When the chain carbon number is an odd number, the melting point of the polyester resin is lower than when the chain carbon number is an even number, and the melting point tends to be a value within the numerical range described later.

  Specific examples of the aliphatic diol include ethylene glycol, 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, Examples thereof include, but are not limited to, 1,18-octadecanediol, 1,20-eicosanediol, and the like. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable in view of availability, and 1,9-nonanediol is preferable in terms of a low melting point.

The alcohol-derived constituent component has an aliphatic diol-derived constituent component content of 80 constituent mol% or more, and includes other components as necessary. As the alcohol-derived constituent component, the content of the aliphatic diol-derived constituent component is preferably 90 constituent mol% or more.
When the content of the aliphatic diol-derived constituent component is less than 80 mol%, the crystallinity of the polyester resin is lowered and the melting point is lowered, so that toner blocking resistance, image storage stability, and low-temperature fixability deteriorate. May end up.

Other components included as necessary include diol-derived components having double bonds and diol-derived components having sulfonic acid groups.
Examples of the diol having a double bond include 2-butene-1,4-diol, 3-butene-1,6-diol, 4-butene-1,8-diol, and the like.
Examples of the diol having a sulfonic acid group include 1,4-dihydroxy-2-sulfonic acid benzene sodium salt, 1,3-dihydroxymethyl-5-sulfonic acid benzene sodium salt, and 2-sulfo-1,4-butanediol sodium. Examples include salts.

When adding these alcohol-derived components other than aliphatic diol-derived components (diol-derived component having a double bond and diol-derived component having a sulfonic acid group), the content in these alcohol-derived components Is preferably 1 to 20 mol%, more preferably 2 to 10 mol%.
When the content of the alcohol-derived constituent component other than the aliphatic diol-derived constituent component is less than 1 constituent mol%, the pigment dispersion is not good, the emulsified particle size is large, and it is difficult to adjust the toner diameter by aggregation. On the other hand, if it exceeds 20 component mol%, the crystallinity of the polyester resin is lowered, the melting point is lowered, the storability of the image is deteriorated, or the emulsified particle size is too small to dissolve in water. Latex may not occur.

As melting | fusing point of the said polyester resin, it is preferable that it is 60-120 degreeC, and it is more preferable that it is 70-100 degreeC.
When the melting point is less than 60 ° C., powder aggregation tends to occur and the stability of a fixed image may deteriorate. On the other hand, when the melting point exceeds 120 ° C., low-temperature fixing may not be possible.
In the present invention, the melting point of the polyester resin is measured by using a differential scanning calorimeter (DSC), and the top of the endothermic peak when measured at a heating rate of 10 ° C./min from room temperature to 150 ° C. The value of was used. The production of the polyester resin can be carried out at a polymerization temperature of 180 to 230 ° C., and the reaction system is reacted under reduced pressure as necessary to remove water and alcohol generated during condensation.

  If the monomer is not dissolved or compatible at the reaction temperature, a high boiling point solvent is added as a solubilizer and dissolved. In the polycondensation reaction, the dissolution auxiliary solvent is distilled off. If there is a monomer with poor compatibility in the copolymerization reaction, it is advisable to condense the monomer with poor compatibility with the monomer and the acid or alcohol to be polycondensed in advance before polycondensing with the main component. .

Catalysts that can be used in the production of the polyester resin include alkali metal compounds such as sodium and lithium, alkaline earth metal compounds such as magnesium and calcium, and metal compounds such as zinc, manganese, antimony, titanium, tin, zirconium, and germanium. , Phosphorous acid compounds, phosphoric acid compounds, and amine compounds. Specific examples include the following compounds.
For example, sodium acetate, sodium carbonate, lithium acetate, lithium carbonate, calcium acetate, calcium stearate, magnesium acetate, zinc acetate, zinc stearate, zinc naphthenate, zinc chloride, manganese acetate, manganese naphthenate, titanium tetraethoxide, titanium Tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, antimony trioxide, triphenylantimony, tributylantimony, tin formate, tin oxalate, tetraphenyltin, dibutyltin dichloride, dibutyltin oxide, diphenyltin oxide, zirconium tetrabutoxide, naphthene Zirconate, zirconyl carbonate, zirconyl acetate, zirconyl stearate, zirconyl octylate, germanium oxide, triphenyl Phosphite, tris (2,4-di -t- butyl-phenyl) phosphite, ethyltriphenylphosphonium bromide, triethylamine, compounds such as triphenyl amine.

  The method for producing the polyester resin is not particularly limited, and can be produced by a general polyester polymerization method in which an acid component and an alcohol component are reacted. For example, direct polycondensation, transesterification method, etc. Produced separately for different types. The molar ratio (acid component / alcohol component) when the acid component reacts with the alcohol component varies depending on the reaction conditions and the like, and cannot be generally stated, but is usually about 1/1.

Among the crystalline polyesters as described above, a crystalline polyester resin having an ester concentration M defined by the following (formula 1) of 0.01 or more and 0.12 or less is preferable.
M = K / A (Formula 1)
(In the above formula, M represents the ester concentration, K represents the number of ester groups in the polymer, and A represents the number of atoms constituting the polymer polymer chain.)
The “ester concentration M” characteristic of the present invention is an index indicating the ester group content in the polymer of the crystalline polyester resin.
The “number of ester groups in the polymer” represented by K in the above formula refers to the number of ester bonds contained in the whole polymer.

  The “number of atoms constituting the polymer polymer chain” represented by A in the above formula is the total number of atoms constituting the polymer polymer chain, and includes all the atoms involved in the ester bond. It does not include the number of atoms of the branched portion in the constituent parts of. That is, carbon atoms and oxygen atoms derived from carboxyl groups and alcohol groups involved in ester bonds (two oxygen atoms in one ester bond) and the six carbons constituting the polymer chain, for example, in the aromatic ring, Although included in the calculation of the number of atoms, for example, a hydrogen atom in an aromatic ring or an alkyl group, or an atom or atomic group of a substituent thereof constituting the polymer chain is not included in the calculation of the number of atoms.

To explain with a specific example, among the total of 10 atoms of 6 carbon atoms and 4 hydrogen atoms in the phenylene group constituting the polymer chain, the above-mentioned “number of atoms A constituting the polymer polymer chain” Included are only six carbon atoms, and even if the hydrogen is replaced by any substituent, the atoms constituting the substituent are the above-mentioned “number of atoms constituting the polymer polymer chain”. A ”is not included.
The crystalline polyester resin has one repeating unit (for example, when the polymer is represented by HO— [COR ₁ COOR ₂ O—] n—H, the one repeating unit is represented in []). In the case of a single polymer consisting of only two ester bonds in one repeating unit (that is, the number of ester groups K ′ = 2 in the repeating unit), the ester concentration M is expressed by the following formula: (1-1).
M = 2 / A ′ (Formula 1-1)
(In the above formula, M represents the ester concentration, and A ′ represents the number of atoms constituting the polymer chain in one repeating unit.)

When the crystalline polyester resin is a copolymer composed of a plurality of copolymerized units, the number of ester groups KX and the number of atoms AX constituting the polymer chain are determined for each copolymerized unit, and the copolymerization ratio is obtained. Can be obtained by summing each of the values and substituting them into (Equation 1). For example, there are three copolymer units of Xa, Xb and Xc, and the copolymerization ratio thereof is a: b: c (where a + b + c = 1)
The ester concentration M for the compound [(Xa) a (Xb) b (Xc) c] can be obtained by the following formula (1-2).
M = {KXa * a + KXb * b + KXc * c}
/ {AXa × a + AXb × b + AXc × c} (Formula 1-2)
(In the above formula, M represents the ester concentration, KXa represents the copolymer unit Xa, KXb represents the copolymer unit Xb, KXc represents the number of each ester group in the copolymer unit Xc, AXa represents the copolymer unit Xa, AXb The polymerization units Xb and AXc represent the number of atoms constituting each polymer chain in the copolymerization unit Xc.)

  In the case where a crystalline polyester resin is used as the binder resin, it has been clarified by the present inventors that the amount of ester groups present in the polymer has a particularly great influence on the chargeability of the toner. Therefore, keeping the amount of ester groups in the polymer low within a range that does not impair the low-temperature fixability is the key to improving the chargeability. In the present invention, in the crystalline polyester resin used as the binder resin, the ester concentration M defined by the above (formula 1) is suppressed to 0.01 or more and 0.13 or less to prevent toner blocking resistance and image storage. In addition, it is possible to obtain a toner having excellent chargeability and low-temperature fixability and also excellent chargeability.

When the ester concentration M is less than 0.01, the chargeability is good, but the melting point of the resin becomes too high, so that the low-temperature fixability is lowered. The lower limit of the ester concentration M is more preferably 0.04 or more.
On the other hand, if the ester concentration M exceeds 0.13, the chargeability is lowered and the melting point of the resin is too low, so that the stability of the fixed image and the powder blocking property are lowered. The upper limit of the ester concentration M is more preferably 0.10 or less.

In the toner of the present invention, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass of the resin forming the core part has an ester concentration M defined by the above (formula 1) of 0.01 or more and 0%. It is preferably a crystalline polyester resin (hereinafter, simply referred to as “specific polyester resin”) that is .13 or less.
All polyester resins including specific polyester resins are synthesized from an acid (dicarboxylic acid) component and an alcohol (diol) component. In the following description, in the polyester resin, the component that was an acid component before the synthesis of the polyester resin is referred to as “acid-derived component”, and the component that was the alcohol component before the synthesis of the polyester resin is referred to as “alcohol. "Derived component".
The specific polyester resin needs to be a crystalline polyester resin. When the specific polyester resin is not crystalline, that is, amorphous, it cannot maintain toner blocking resistance and image storage stability while ensuring good low-temperature fixability.

  Further, when the specific polyester resin has a cross-linked structure due to an unsaturated bond, it has a particularly wide fixing latitude with good offset resistance and a toner in a recording medium such as paper. Thus, an electrophotographic toner capable of satisfying prevention of excessive penetration of the toner can be obtained.

The binder resin that forms the shell of the toner of the present invention is not particularly limited, and examples thereof include an amorphous polyester resin, a vinyl-based amorphous resin, and the like, but it must be present as a resin latex. The latex may be prepared by emulsion polymerization, or a resin obtained by polycondensation, such as polyester, may be emulsified by mechanical force. Examples of the emulsifier include an ultra turrax, a gorin homogenizer, a clear mix, a cavitron, and the like, but any latex can be used.
The latex diameter is preferably 0.02 μm to 1.0 μm. Preferably, it is 0.04 μm to 0.6 μm. In order to make the step difference of the shell in the core-shell structure toner of the present invention 0.3 μm or more, it is preferable to agglomerate the shell latex to about 0.5 μm, and in advance, the shell latex is about 0.5 μm in another container. It is also effective to contact the core particles after agglomeration.
Since the resin needs to be a film and function as the outermost layer of the toner, the glass transition point is preferably 40 ° C. or higher and 80 ° C. or lower, and the weight average molecular weight is preferably 10,000 or higher and 40,000 or lower. When the shell latex is adhered to the spherical toner obtained by the EA manufacturing method, the solid content concentration is 3-30% by mass, more preferably 5-15% by mass. If the concentration is too low, it is difficult to adhere, and if the concentration is high, relatively uniform adhesion tends to proceed, the viscosity of the reaction solution increases, and energy is required for stirring.

<Colorant>
There is no restriction | limiting in particular as a coloring agent in the toner of this invention, A well-known coloring agent is mentioned, It can select suitably according to the objective. One type of pigment may be used alone, or two or more types of pigments of the same type may be mixed and used. Two or more different types of pigments may be mixed and used. Specific examples of the colorant include carbon black such as furnace black, channel black, acetylene black, and thermal black, inorganic pigments such as bengara, aniline black, bitumen, titanium oxide, and magnetic powder, fast yellow, and monoazo. Yellow, disazo yellow, pyrazolone red, chelate red, brilliant carmine (3B, 6B, etc.), azo pigments such as para brown, phthalocyanine pigments such as copper phthalocyanine, metal-free phthalocyanine, flavantron yellow, dibromoanthrone orange, perylene red, quinacridone Examples thereof include condensed polycyclic pigments such as red and dioxazine violet.

  Chrome Yellow, Hansa Yellow, Benzidine Yellow, Slen Yellow, Quinoline Yellow, Permanent Orange GTR, Pyrazolone Orange, Vulcan Orange, Watch Young Red, Permanent Red, Dupont Oil Red, Resol Red, Rhodamine B Lake, Lake Red C, Rose Various pigments such as Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, Para Brown; Acridine, Xanthene, Azo, Benzoquinone, Azine, Anthraquinone, dioxazine, thiazine, azomethine, indigo, thioindigo, phthalocyanine, aniline black , Polymethine dyes, triphenylmethane dyes, diphenylmethane dyes, thiazole type, various dyes such as xanthene; and the like. You may mix black pigments, such as carbon black, and dye to such an extent that transparency is not reduced to these colorants. Moreover, a disperse dye, an oil-soluble dye, etc. are mentioned.

The content of the colorant in the electrophotographic toner of the present invention is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the binder resin, as long as the smoothness of the image surface after fixing is not impaired. Of these numerical ranges, as many as possible are preferable. Increasing the content of the colorant is advantageous in that the thickness of the image can be reduced when an image having the same density is obtained, which is effective in preventing offset.
In addition, by appropriately selecting the type of the colorant, each color toner such as yellow toner, magenta toner, cyan toner, and black toner can be obtained.

<Other ingredients>
The other components that can be used in the toner of the present invention are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include various known additives such as inorganic fine particles, organic fine particles, charge control agents, and release agents. Etc.

(Inorganic fine particles)
The inorganic fine particles are generally used for the purpose of improving toner fluidity. Examples of the inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, cerium chloride. , Bengara, chromium oxide, cerium oxide, antimony trioxide, magnesium oxide, zirconium oxide, silicon carbide, silicon nitride and the like. Among these, silica fine particles are preferable, and silica fine particles that have been hydrophobized are particularly preferable. Usually, the inorganic fine particles are externally added and adhered to the toner surface.
The average primary particle size (number average particle size) of the inorganic fine particles is preferably 1 to 1000 nm, and the addition amount (external addition) is 0.01 to 20 parts by mass with respect to 100 parts by mass of the toner. preferable.

(Organic fine particles)
The organic fine particles are generally used for the purpose of improving cleaning properties and transferability. Examples of the organic fine particles include fine particles such as polystyrene, polymethyl methacrylate, and polyvinylidene fluoride. Usually, the organic fine particles are externally added and adhered to the toner surface.

(Charge control agent)
The charge control agent is generally used for the purpose of improving chargeability. Examples of the charge control agent include salicylic acid metal salts, metal-containing azo compounds, nigrosine and quaternary ammonium salts.

(Release agent)
The release agent is generally used for the purpose of improving release properties. Specific examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide Kinds: Plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc. Mineral / petroleum waxes; ester waxes such as fatty acid esters, montanic acid esters, and carboxylic acid esters. In this invention, these mold release agents may be used individually by 1 type, and may use 2 or more types together.

  The addition amount of these release agents is preferably 0.5 to 50% by mass, more preferably 1 to 30% by mass, and further preferably 5 to 15% by mass with respect to the total amount of toner. If it is less than 0.5% by mass, there is no effect of adding a release agent, and if it is 50% by mass or more, the chargeability is likely to be affected, or the toner is easily destroyed inside the developing machine. As a result, the toner tends to be spent on the carrier and the charge is likely to be lowered. For example, when color toner is used, the toner image tends to be insufficiently oozed out on the image surface during fixing. In this case, the release agent tends to stay in the film, which is not preferable because the transparency is deteriorated.

<Other configurations>
The surface of the electrophotographic toner of the present invention may be covered with a surface layer. It is desirable that the surface layer does not greatly affect the mechanical properties and melt viscoelastic properties of the entire toner. For example, if the surface layer of non-melting or high melting point covers the toner thickly, the low-temperature fixability due to the use of the crystalline polyester resin cannot be sufficiently exhibited.
Therefore, it is desirable that the thickness of the surface layer is thin, and specifically, it is preferable to be within a range of 0.001 to 0.5 μm.

In order to form a thin surface layer in the above range, a method of chemically treating the surface of particles containing binder resin, colorant, inorganic fine particles added as necessary, and other materials is preferable. used.
Examples of the component constituting the surface layer include silane coupling agents, isocyanates, vinyl monomers, and the like, and it is preferable that a polar group is introduced into the component, and it is chemically bonded. As a result, the adhesive force between the toner and the transfer medium such as paper increases.
The polar group may be any polar functional group, for example, carboxyl group, carbonyl group, epoxy group, ether group, hydroxyl group, amino group, imino group, cyano group, amide group, imide group , Ester groups, sulfone groups and the like.
Examples of the chemical treatment method include a strong oxidizing substance such as a peroxide, a method of oxidizing by ozone oxidation, plasma oxidation or the like, a method of bonding a polymerizable monomer containing a polar group by graft polymerization, and the like. By the chemical treatment, the polar group is firmly bonded to the molecular chain of the crystalline resin through a covalent bond.

  In the present invention, a chargeable substance may be chemically or physically attached to the toner particle surface. Further, fine particles such as metal, metal oxide, metal salt, ceramic, resin, and carbon black may be externally added for the purpose of improving charging property, conductivity, powder fluidity, lubricity and the like.

The volume average particle size of the electrophotographic toner of the present invention is preferably 1 to 20 μm, more preferably 2 to 8 μm, and the number average particle size is preferably 1 to 20 μm, more preferably 2 to 8 μm.
The volume average particle size and the number average particle size can be determined, for example, by measuring with a 50 μm aperture diameter using a Coulter counter [TA-II] type (manufactured by Coulter). At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (Isoton aqueous solution: manufactured by Coulter, Inc.) and dispersed by ultrasonic waves for 30 seconds or more.

Furthermore, the electrophotographic toner of the present invention preferably has a melting point in the temperature range of 60 to 120 ° C. For example, the crystalline polyester resin having the above-mentioned specific ester concentration rapidly decreases in viscosity at the melting point, and therefore aggregates and causes blocking when stored at a temperature equal to or higher than the melting point. Therefore, when such a crystalline polyester resin is contained as the main component of the binder resin, the melting point of the electrophotographic toner is higher than the temperature exposed during storage or use, that is, 60 ° C. or more. Is preferred. On the other hand, if the melting point is higher than 120 ° C., it may be difficult to achieve low-temperature fixing. The electrophotographic toner of the present invention preferably has a melting point in the temperature range of 70 to 100 ° C.
The melting point of the electrophotographic toner of the present invention can be determined as the melting peak temperature of input compensated differential scanning calorimetry as shown in JIS K-7121. The crystalline resin may show a plurality of melting peaks, but in the present invention, the maximum peak is regarded as the melting point.

[Method for producing toner for electrophotography]
In the toner production method of the present invention, a fine particle dispersion of a shell-forming resin is added to a core dispersion (hereinafter referred to as “core dispersion”) containing a binder resin mainly composed of a crystalline resin and a colorant. And the fine particles of the shell-forming resin are adhered and aggregated on the core surface. In addition, it is preferable to heat the particles adhering and aggregating on the core surface in the vicinity of the glass transition point and to semi-fuse them.
Examples of the core dispersion include an emulsion aggregation method, a suspension polymerization method, a dispersion polymerization method, and the like, and a method in which a solution containing a binder resin and a colorant is dispersed in water together with a dispersant using high shearing force. Among these, the emulsion aggregation method is preferable. These are well known methods.

  The emulsion aggregation method used when preparing the core dispersion is to prepare a fine particle dispersion (emulsion, solid dispersion) containing the components (binder resin, colorant, etc.) contained in the core. In this method, fine particles are mixed to form agglomerated particles by agglomerating fine particles, and then the agglomerated particles are heated to a melting point or a glass transition point of the binder resin or more to thermally fuse the agglomerated particles. In the present invention, since a crystalline resin is included, heating is performed to the melting point or higher. In addition to a method of preparing a fine particle dispersion corresponding to each component, for example, when preparing an emulsion of a certain component, other components are added to the solvent to simultaneously emulsify two or more components, and fine particles A plurality of components may be included therein.

In the following, a toner production method using this emulsion aggregation method in the step of producing the core and the step of producing the shell will be described.
The emulsion aggregation method is as described above. More specifically, for example, a fine particle dispersion (emulsion, solid dispersion) of a binder resin and other toner components (colorant, release agent, etc.) After the fine particle dispersion is mixed, fine particles are aggregated to form aggregated particles, and the aggregated particles are heated to the melting point or glass transition point of the binder resin or higher to thermally fuse the aggregated particles.
In the method for producing a core-shell toner of the present invention using this method, first, a fine particle dispersion of a binder resin mainly composed of a crystalline resin and a fine colorant dispersion are mixed, and the mixture is mixed with the binder resin. Heat to a temperature higher than the melting point to agglomerate and fuse the binder resin fine particles and colorant fine particles to prepare a core dispersion (preparation of the core dispersion using the emulsion aggregation method), and to this, a shell forming material In this method, fine particles of a shell-forming material are mixed and agglomerated on the core surface (formation of a shell using the emulsion aggregation method) to form a shell having a hemispherical protrusion with a step of 0.3 μm or more. is there.

<Process for preparing core dispersion>
(Preparation of fine particle dispersion of binder resin based on crystalline resin)
The fine particle dispersion of the binder resin is prepared by applying a shearing force to the liquid obtained by mixing the aqueous medium and the binder resin, or by applying a shearing force to the liquid obtained by mixing the organic solvent solution of the aqueous medium and the binder resin. It is performed by giving and emulsifying. In addition, before forming the emulsified particles, a colorant or an organic solvent dispersion of a colorant may be mixed in an organic solvent solution of a binder resin, and an aqueous medium may be mixed and emulsified. (If the colorant is added at this stage, a fine particle dispersion of the binder resin and the colorant is prepared. Therefore, the aggregation and coalescence process can be performed without preparing the following colorant fine particle dispersion. it can.)
Further, by heating during emulsification or dispersion, the viscosity of the binder resin can be lowered to form emulsified particles or dispersed particles (hereinafter, both may be collectively referred to as emulsified particles).
Examples of the organic solvent include ethyl acetate and toluene, which are appropriately selected according to the polyester resin.
The organic solvent is used in an amount of 50 to 5000 with respect to 100 parts by mass of the total amount of the binder resin and other monomers used as necessary (hereinafter, sometimes simply referred to as “polymer”). A mass part is preferable and 120-1000 mass parts is more preferable.

Moreover, a dispersing agent can also be used in order to stabilize the dispersed particles or emulsified particles and increase the viscosity of the aqueous medium.
Examples of the dispersant include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium polyacrylate, and sodium polymethacrylate, sodium dodecylbenzenesulfonate, sodium octadecylsulfate, and oleic acid. Anionic surfactants such as sodium, sodium laurate, potassium stearate, cationic surfactants such as laurylamine acetate, stearylamine acetate, lauryltrimethylammonium chloride, zwitterionic surfactants such as lauryldimethylamine oxide, Such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkylamine, etc. Anion surfactants such as surfactants, tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium carbonate, and inorganic compounds such as barium carbonate.

When an inorganic compound is used as the dispersant, a commercially available product may be used as it is. However, for the purpose of obtaining particles, a method of producing fine particles of an inorganic compound in the dispersant may be employed.
As the usage-amount of the said dispersing agent, 0.01-20 mass parts is preferable with respect to 100 mass parts of said polyester resins (binder resin).

  In the dispersion or emulsification step, a polyester resin obtained by copolymerizing a dicarboxylic acid having a sulfonic acid group as a binder resin (that is, a suitable amount of a dicarboxylic acid-derived component having a sulfonic acid group in the acid-derived component) In the present invention, dispersion stabilizers such as surfactants can be reduced, or dispersed particles or emulsified particles can be formed without using them.

  Examples of the emulsifier or the disperser used when forming the dispersed particles or the emulsified particles include a homogenizer, a homomixer, a pressure kneader, an extruder, and a media disperser. The size of the emulsified particles (droplets) of the polyester resin is preferably 0.01 to 1 μm, more preferably 0.03 to 0.3 μm, more preferably 0.03 to 0.03 in terms of the average particle size (volume average particle size). 0.4 μm is more preferable.

(Preparation of colorant fine particle dispersion)
As a method for dispersing the colorant, any method such as a general dispersion method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, or a dyno mill can be used, and is not limited at all.
If necessary, an aqueous dispersion of these colorants can be prepared using a surfactant, or an organic solvent dispersion of these colorants can be prepared using a dispersant. As the surfactant and the dispersing agent used for dispersion, the same dispersing agents that can be used when dispersing the binder resin can be used.
The addition amount of the colorant is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, and still more preferably 2 to 10% by mass with respect to the total amount of the polymer. 2 to 7% by mass is particularly preferable.

(Production of aggregated particles)
Aggregated particles are prepared by mixing the fine particle dispersion of the binder resin mainly composed of the crystalline resin prepared as described above and the colorant fine particle dispersion. In the aggregating step, the obtained binder resin fine particle dispersion and colorant fine particle dispersion are mixed to aggregate the binder resin fine particles and the colorant fine particles to form aggregated particles. At this time, the mixed solution is preferably heated to a temperature near the melting point of the binder resin and lower than the melting point. Moreover, this process is performed under stirring.

It is also effective to use a flocculant when forming the agglomerated particles. As the flocculant to be used, a surfactant having a reverse polarity to the surfactant used for the dispersant, an inorganic metal salt, and a metal complex having a valence of 2 or more can be preferably used. In particular, the use of a metal complex is particularly preferable because the amount of the surfactant used can be reduced and the charging characteristics are improved.
Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include inorganic metal salt polymers. Of these, aluminum salts and polymers thereof are particularly preferred. In order to obtain a sharper particle size distribution, the valence of the inorganic metal salt is bivalent than monovalent, trivalent than bivalent, trivalent than trivalent, and tetravalent than trivalent. The inorganic metal salt polymer is more suitable.

(Fusion of aggregated particles)
In the fusion step when preparing the core dispersion, the agglomeration is stopped by stirring the same as in the agglomeration step, and the pH is raised to 6 or more, and heating is performed at a temperature equal to or higher than the melting point of the binder resin. By doing so, the agglomerated particles are fused. The upper limit of the heating temperature is about from the melting point to a temperature of 20 ° C. or higher. The heating time may be performed to such an extent that the fusion is sufficiently performed, and may be performed for about 0.5 to 10 hours.

<Process of mixing fine particle dispersion of shell-forming resin in core dispersion and attaching and agglomerating fine particles of shell-forming resin to core surface>
The core dispersion prepared as described above is mixed with the fine particle dispersion of the shell forming resin, and the fine particles of the shell forming resin are adhered and aggregated on the core surface. This step is performed with stirring.
In order to assist adhesion and aggregation, it is desirable to use a coagulant together. As the aggregating agent, those used in the agglomeration / fusion step when preparing the core dispersion described above can be used as well. Since the amount used varies depending on the type of the flocculant, it is determined according to the cohesive strength of the flocculant. If too much is added, the cores will aggregate, and if too little, a shell layer will be difficult to form. When a metal salt is used as the flocculant, generally, when the valence of the metal salt is large, the cohesive force is strong and the amount of the flocculant is small. In the case of polyaluminum chloride, it is appropriate to use 0.05 to 0.03% by mass with respect to the shell material (solid content). Desirable conditions are such that agglomerates of resin fine particles for forming shells adhere to the core as a shell, and it is preferable to add an aggregating agent before introducing the shell material into the core dispersion.
The amount of the shell-forming resin dispersion is 15 to 120% by mass, more preferably 25 to 100% by mass, and still more preferably 35 to 80% by mass with respect to the core dispersion. If the amount of the shell-forming dispersion is small, it is difficult to form a concavo-convex structure or a place where it cannot be partially covered. On the other hand, if the amount is too large, the thickness of the entire shell layer increases, so that the fixing temperature increases.

  The shell with unevenness obtained in this way is heated near the temperature of the glass transition point of the shell-forming resin, and the agglomerated fine particles of the shell-forming resin and the core are semi-adhered at the interface, or the shell-forming resin. It is preferable to semi-adhere the resin fine particles.

  Thereafter, the toner with the shell semi-fused is taken out of the stirrer, washed and dried. In drying, it is effective for shell formation to slowly dehydrate at a temperature not higher than Tg of the shell forming resin. An oven dryer or a flash jet dryer is effective. If some of the fine particles of the shell-forming resin are not yet melted even after this drying step, it is also effective to further smooth the uneven surface using mechanical force.

The fused particles obtained by fusing can be made into toner particles through a solid-liquid separation process such as filtration and, if necessary, a washing process and a drying process. In this case, in order to ensure sufficient charging characteristics and reliability as a toner, it is preferable to sufficiently wash in the washing step.
In the drying process, an arbitrary method such as a normal vibration type fluidized drying method, a spray drying method, a freeze drying method, or a flash jet method can be adopted. It is desirable that the toner particles have a moisture content after drying of 1.0% or less, preferably 0.5% or less.

In the fusion step, a crosslinking reaction may be performed when the binder resin is heated to the melting point or higher, or after the fusion is completed. Moreover, a crosslinking reaction can also be performed simultaneously with aggregation. When the crosslinking reaction is performed, for example, an unsaturated crystalline polyester resin obtained by copolymerizing a double bond component as a binder resin is used, and a radical reaction is caused in the resin to introduce a crosslinked structure. At this time, the following polymerization initiator is used.
Examples of the polymerization initiator include t-butyl peroxy-2-ethylhexanoate, cumyl perpivalate, t-butyl peroxylaurate, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, di-t. -Butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane 1,1-bis (t-butylperoxy) cyclohexane, 1,4-bis (t-butylperoxycarbonyl) ) Cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl 4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane,

  1,3-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butyl) Peroxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, di-t-butyldiperoxyisophthalate, 2,2-bis (4,4-di-t-butylper) Oxycyclohexyl) propane, di-t-butylperoxy α-methylsuccinate, di-t-butylperoxydimethylglutarate, di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, diethylene glycol-bis (t-butylperoxycarbonate), -T-butylperoxytrimethyladipate, tris (t-butylperoxy) triazine, vinyltris (t-butylperoxy) silane, 2,2'-azobis (2-methylpropionamidine dihydrochloride), 2,2 ' -Azobis [N- (2-carboxyethyl) -2-methylpropionamidine], 4,4'-azobis (4-cyanovaleric acid) and the like.

These polymerization initiators can be used alone or in combination of two or more. The amount and type of the polymerization initiator are selected depending on the amount of unsaturated sites in the binder resin and the type and amount of the coexisting colorant.
The polymerization initiator may be mixed with the polymer in advance before preparing the fine particle dispersion of the binder resin, or may be incorporated into the aggregate in the aggregation step. Further, it may be introduced after the fusion step or after the fusion step. In the case of introduction after the aggregation step, the fusion step, or the fusion step, a solution in which the polymerization initiator is dissolved or emulsified is added to a particle dispersion (resin particle dispersion or the like). These polymerization initiators may be added with known crosslinking agents, chain transfer agents, polymerization inhibitors and the like for the purpose of controlling the degree of polymerization.

  When the toner of the present invention contains a release agent (internal addition), a dispersion (including an emulsion) of release agent fine particles is prepared in the same manner as the colorant, and the crystalline resin is the main component. In the step of mixing the binder resin fine particle dispersion and the colorant fine particle dispersion, the release agent fine particle dispersion is also mixed, and then the core dispersion is prepared in the same manner. It should just adhere to.

[Electrophotographic developer]
The electrophotographic toner of the present invention obtained as described above can be used as it is as a one-component developer or as a toner in the two-component developer of the present invention comprising a carrier and a toner. Hereinafter, the two-component developer of the present invention will be described.
<Two-component developer>
The carrier that can be used in the two-component developer is not particularly limited, and a known carrier can be used. For example, a resin-coated carrier having a resin coating layer on the surface of the core material can be exemplified. Further, a resin-dispersed carrier in which a conductive material or the like is dispersed in a matrix resin may be used.

  Coating resins and matrix resins used for carriers include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic. Examples thereof include, but are not limited to, acid copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenol resins, epoxy resins and the like.

Examples of the conductive material include metals such as gold, silver and copper, carbon black, titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black. It is not limited.
Examples of the core material of the carrier include magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to use the carrier for the magnetic brush method, it is a magnetic material. It is preferable.
The volume average particle size of the core material of the carrier is generally 10 to 500 μm, preferably 30 to 100 μm.
In order to coat the surface of the core material of the carrier with a resin, there may be mentioned a method of coating with a coating layer forming solution in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited and may be appropriately selected in consideration of the coating resin to be used, coating suitability, and the like.

  Specific resin coating methods include an immersion method in which the carrier core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed onto the surface of the carrier core material, and the carrier core material is fluidized air. And a kneader coater method in which the carrier core material and the coating layer forming solution are mixed in a kneader coater and the solvent is removed in a kneader coater.

  The mixing ratio (mass ratio) of the electrophotographic toner of the present invention and the carrier in the two-component developer is in the range of toner: carrier = 1: 100 to 30: 100, and 3: 100 to 20: A range of about 100 is more preferable.

[Image forming method]
Next, the image forming method of the present invention using the electrophotographic toner of the present invention or the two-component developer of the present invention will be described.
The image forming method uses a latent image forming step of forming an electrostatic latent image on the surface of the latent image holding member, and a developer carried on the developer carrying member, and an electrostatic image formed on the surface of the latent image holding member. A developing process for developing the latent image to form a toner image, a transfer process for transferring the toner image formed on the surface of the latent image holding member to the surface of the transfer material such as paper, and the image transferred to the surface of the transfer target And a fixing step for heat-fixing the toner image, wherein the developer is the electrophotographic toner of the present invention or the two-component developer of the present invention.

The developer may be either a one-component system or a two-component system. In the case of a one-component system, the electrophotographic toner of the present invention is used as it is. In the case of a two-component system, the two-component developer of the present invention obtained by mixing the electrophotographic toner of the present invention and the carrier is used. Used.
As each of the above steps, a known step in the image forming method can be used.

As the latent image holding member, for example, an electrophotographic photosensitive member and a dielectric recording member can be used.
In the case of an electrophotographic photosensitive member, the surface of the electrophotographic photosensitive member is uniformly charged by a corotron charger, a contact charger or the like and then exposed to form an electrostatic latent image (latent image forming step). Next, the toner particles are adhered to the electrostatic latent image in contact with or in proximity to a developing roll having a developer layer formed on the surface, thereby forming a toner image on the electrophotographic photosensitive member (developing step). The formed toner image is transferred onto the surface of a transfer medium such as paper using a corotron charger or the like (transfer process). Further, the toner image transferred to the surface of the transfer target is heat-fixed by a fixing device, and a final toner image is formed.
In the heat fixing by the fixing machine, a release agent is usually supplied to a fixing member in the fixing machine in order to prevent an offset or the like.

  In the electrophotographic toner of the present invention (including those contained in the two-component developer of the present invention, the same applies hereinafter), if the binder resin has a crosslinked structure, it is excellent in releasability due to its effect. Fixing can be carried out without using a release agent or without using a release agent.

The release agent is preferably not used from the viewpoint of eliminating oil adhesion to the transfer target and image after fixing. However, when the supply amount of the release agent is 0 mg / cm ² , the fixing agent is fixed during fixing. Since the amount of wear of the fixing member may increase and the durability of the fixing member may decrease when the member and a transfer medium such as paper come into contact with each other. It is preferable that the amount used is supplied to the fixing member in a small amount within a range of 8.0 × 10 ⁻³ mg / cm ² or less.

When the supply amount of the release agent exceeds 8.0 × 10 ⁻³ mg / cm ² , the image quality deteriorates due to the release agent adhering to the image surface after fixing, and in particular, transmitted light such as OHP is transmitted. When used, such a phenomenon may be prominent. Further, the adhesion of the release agent to the transfer target becomes remarkable, and stickiness may occur. Furthermore, the larger the supply amount of the release agent, the larger the capacity of the tank for storing the release agent, which causes an increase in the size of the fixing device itself.

  Although there is no restriction | limiting in particular as said mold release agent, For example, liquid mold release agents, such as modified oils, such as dimethyl silicone oil, fluorine oil, fluoro silicone oil, and amino modified silicone oil, are mentioned. Among these, modified oils such as amino-modified silicone oil are preferable because they are adsorbed on the surface of the fixing member and can form a homogeneous release agent layer, because they have excellent wettability to the fixing member. Further, from the viewpoint of forming a homogeneous release agent layer, fluorine oil and fluorosilicone oil are preferable.

  Fluorine oil or fluorosilicone oil is used as the release agent because the toner for electrophotography of the present invention is not used, and the conventional image forming method cannot reduce the supply amount of the release agent itself. Although not practical in terms of cost, when the electrophotographic toner of the present invention is used, since the supply amount of the release agent can be drastically reduced, there is no practical problem in terms of cost.

  The method for supplying the release agent to the surface of the roller or belt, which is a fixing member used for the thermocompression bonding, is not particularly limited. For example, a pad method using a pad impregnated with a liquid release agent, a web method, Examples thereof include a roller method and a non-contact type shower method (spray method). Among these, a web method and a roller method are preferable. These methods are advantageous in that the release agent can be supplied uniformly and it is easy to control the supply amount. In order to supply the release agent uniformly to the entire fixing member by the shower method, it is necessary to use a separate blade or the like.

The supply amount of the release agent can be measured as follows. That is, when a normal paper (typically a copy paper manufactured by Fuji Xerox Co., Ltd., trade name J paper) used in a general copying machine is passed through a fixing member supplied with a release agent on its surface. The release agent adheres to the plain paper. The attached release agent is extracted using a Soxhlet extractor. Here, hexane is used as the solvent.
By quantifying the amount of the release agent contained in the hexane with an atomic absorption analyzer, the amount of the release agent adhering to the plain paper can be quantified. This amount is defined as the amount of release agent supplied to the fixing member.

Examples of the transfer target (recording material) to which the toner image is transferred include plain paper and OHP sheet used for electrophotographic copying machines, printers, and the like.
In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer object is as smooth as possible. For example, coated paper in which the surface of plain paper is coated with a resin or the like, art paper for printing Etc. can be used suitably.

  According to the image forming method using the electrophotographic toner of the present invention, since there is no aggregation of the toner, an image with excellent image quality can be formed, low temperature fixing is possible, and storage of the formed image is possible. Excellent in properties. Furthermore, when the binder resin has a cross-linked structure, there is almost no adhesion of the release agent to the transfer target, so use a transfer target that has adhesiveness on the back side, such as a seal or tape. By forming an image, it is possible to manufacture a sticker, a sticker or the like on which a high-density and high-density image is formed.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In the following, “parts” and “%” mean “parts by mass” and “% by mass”, respectively.
(Synthesis of crystalline polyester resin (1))
In a 5 L flask, 1982 parts (9.8 mol) of sebacic acid, 1490 parts (25 mol) of ethylene glycol, 59.2 parts (0.2 mol) of sodium dimethyl 5-sulfonate, 0.2 parts of dibutyltin oxide, The reaction was carried out at 180 ° C. for 5 hours under a nitrogen atmosphere, followed by a condensation reaction at 220 ° C. under reduced pressure. The polymer was sampled on the way, and when the molecular weight became Mw (weight average molecular weight) = 20000 and Mn (number average molecular weight) = 8500 by GPC, the reaction was stopped to obtain a crystalline polyester resin (1). The melting point (DSC peak top) was 71 ° C. The measurement result of the content of sodium dimethyl 5-phthalate by NMR was 1 mol% (vs. all components). The ester concentration is 0.125.

(Synthesis of crystalline polyester resin (2))
In a 5 L flask, 1800 parts (8.9 mol) of sebacic acid, 1073 parts (9.08 mol) of 1,6-hexanediol, 53.8 parts (0.18 mol) of sodium dimethyl 5-sulfonate, and dibutyltin oxide 1.13 parts were reacted at 180 ° C. for 5 hours under a nitrogen atmosphere, followed by a condensation reaction at 220 ° C. under reduced pressure. The polymer was sampled on the way, and when the molecular weight became Mw (weight average molecular weight) = 25400 and Mn (number average molecular weight) = 8500 by GPC, the reaction was stopped to obtain a crystalline polyester resin (2). The melting point (DSC peak top) was 70 ° C. The measurement result of the content of sodium dimethyl 5-phthalate by NMR was 1 mol% (vs. all components). The ester concentration is 0.1.

(Synthesis of crystalline polyester resin (3))
In a 5 L flask, 149.7 parts (9.8 mol) of 1,10-dodecanedioic acid, 901 parts (10 mol) of 1,4-butanediol, 59.2 parts of sodium dimethyl-5-sulfonate (0. 2 mol) and 0.7 parts of dibutyltin oxide were reacted at 180 ° C. for 5 hours under a nitrogen atmosphere, followed by a condensation reaction at 220 ° C. under reduced pressure. The polymer was sampled on the way, and when the molecular weight became Mw = 9000 and Mn = 4500 by GPC, the reaction was stopped to obtain a crystalline polyester resin (3). The melting point (DSC peak top) was 71 ° C. The measurement result of the content of dimethyl 5-sodium phthalate by NMR was 1 mol% (vs. all constituent monomers). The ester concentration is 0.1.

(Synthesis of crystalline polyester resin (4))
To a 5 L flask, 2254 parts (9.8 mol) of 1,10-dodecanedioic acid, 1600 parts (10 mol) of 1,9-nonanediol, 59.2 parts (0.2 mol) of sodium dimethyl-5-sulfonate isophthalate , And 0.7 parts of dibutyltin oxide were reacted at 180 ° C. for 5 hours under a nitrogen atmosphere, followed by a condensation reaction at 220 ° C. under reduced pressure. The polymer was sampled on the way, and when the molecular weight reached Mw = 8500 and Mn = 4300 by GPC, the reaction was stopped to obtain a crystalline polyester resin (4). The melting point (DSC peak top) was 70 ° C. The measurement result of the content of dimethyl 5-sodium phthalate by NMR was 1 mol% (vs. all constituent monomers). The ester concentration is 0.08.

(Synthesis of crystalline polyester resin (5))
In a 5 L flask, 1500 parts (7.4 mol) of sebacic acid, 874 parts (7.4 mol) of 1,6-hexanediol, and 1.13 parts of dibutyltin oxide were reacted at 180 ° C. for 5 hours under a nitrogen atmosphere. Subsequently, a condensation reaction was performed at 220 ° C. under reduced pressure. The polymer was sampled on the way, and when the molecular weight became Mw (weight average molecular weight) = 27200 and Mn (number average molecular weight) = 9300 by GPC, the reaction was stopped to obtain a crystalline polyester resin (5). The melting point (DSC peak top) was 70 ° C. The ester concentration is 0.1.

(Synthesis of non-crystalline polyester resin (1))
In a 1 L flask, 165 parts (0.85 mol) of dimethyl terephthalate, 41.4 parts (0.14 mol) of dimethyl 5-sophthalate, 106.5 parts (1.4 mol) of propylene glycol, 53 of dipropylene glycol 53 .6 parts (0.4 mol), 21.2 parts (0.2 mol) of diethylene glycol, and 0.07 part of dibutyltin oxide were reacted at 180 ° C. for 5 hours under a nitrogen atmosphere, followed by condensation at 220 ° C. under reduced pressure. Reaction was performed. The polymer was sampled on the way, and when the molecular weight reached Mw = 11000 and Mn = 5900 by GPC, the reaction was stopped to obtain an amorphous polyester resin (1). The glass transition temperature (Tg) was 53 ° C. by DSC. The measurement result of the content of dimethyl 5-sodium phthalate by NMR was 7 mol% (vs. all constituent monomers).

(Synthesis of non-crystalline polyester resin (2))
In a 2 L flask, 94 parts (0.48 mol) of dimethyl terephthalate, 94 parts (0.48 mol) of dimethyl isophthalate, 11.8 parts (0.04 mol) of dimethyl isophthalate 5-sodium sulfonate, 80 parts of neopentyl glycol (0.77 mol), 89 parts (1.43 mol) of ethylene glycol, and 0.1 part of dibutyltin oxide were reacted at 180 ° C. for 5 hours under a nitrogen atmosphere, followed by a condensation reaction at 220 ° C. under reduced pressure. . The polymer was sampled on the way, and when the molecular weight reached Mw = 8000 and Mn = 3400 by GPC, the reaction was stopped to obtain an amorphous polyester resin (2). The glass transition temperature (Tg) was 58 ° C. by DSC. The measurement result of the content of dimethyl 5-sodium phthalate by NMR was 2 mol% (with respect to the total constituent monomers).

(Preparation of blue pigment dispersion B-1)
The following composition was mixed and dissolved, and dispersed by homogenizer (IKA Ultra Tarrax) and ultrasonic irradiation to obtain a blue pigment dispersion B-1 having a central particle size of 150 nm.
・ Sian pigment PB15: 3 (Copper phthalocyanine manufactured by Dainippon Ink & Chemicals) 50 parts ・ Anionic surfactant Neogen SC 5 parts ・ Ion-exchanged water 200 parts

(Preparation of release agent dispersion C-1)
The following composition was mixed, heated to 97 ° C., and then dispersed with IKA Ultra Turrax T50. Thereafter, the mixture was dispersed with a gorin homogenizer (manufactured by Reiwa Shoji) and treated 20 times under the conditions of 105 ° C. and 550 kg / cm ² to obtain a release agent dispersion C-1 having a center diameter of 190 nm.
-Paraffin wax (trade name: HNP-9) 100 parts-Anionic surfactant Neogen SC 5 parts-Ion-exchanged water 230 parts

<Synthesis of shell binder resin latex>
19.9 parts of dodecanethiol, 23.9 parts of β-carboxyethyl acrylate, 143.3 parts of butyl acrylate, 652.9 parts of styrene, 15.8 parts of Dowfax (anionic surfactant), 333.7 parts of ion-exchanged water The mixture is emulsified with a homogenizer. Separately, 11.9 parts of Dowfax (anionic surfactant) are dissolved in 740 parts of ion-exchanged water, placed in a 2 L flask, purged with nitrogen, and heated to 75 ° C. 12 parts of the monomer liquid emulsified with the previous homogenizer is added to the flask, and then a liquid prepared by dissolving 12 parts of ammonium persulfate in 60 parts of distilled water is added dropwise. After stirring for 20 minutes, the remaining monomer emulsion is added dropwise over about 4 hours. After completion of the dropwise addition, heating and stirring are further continued for 3 hours. The obtained polymer latex had Mw 17600, Mn 6500, Tg 57 ° C., and particle size 0.1 micron.

<Example 1>
(Preparation of crystalline polyester resin latex (1))
40 parts of the obtained crystalline polyester resin (1) is added to 360 parts of ion-exchanged water, heated to 90 ° C., adjusted to pH = 9 with 5% aqueous ammonia, and 10% dodecylbenzenesulfonic acid aqueous solution 0.8 While adding parts, the mixture was stirred at 8000 rpm using Ultra Turrax T-50 (manufactured by IKA) to prepare a crystalline polyester resin latex (1) having a center diameter of about 300 nm.

(Production of core (1))
The following composition was mixed and dispersed in a round stainless steel flask with Ultra Turrax T50, then the contents in the flask were heated to 55 ° C. with stirring in an oil bath for heating, and held at 55 ° C. for 1 hour.
-Crystalline polyester resin latex (1) 1000 parts-Anionic surfactant 8 parts-Pigment dispersion B-1 25 parts-Release agent dispersion C-1 40 parts-Calcium chloride 10 mass% aqueous solution 10 parts

  Then, when the obtained content was observed with an optical microscope, it was confirmed that about 4.5 μm aggregated particles were generated. Further, the temperature of the heating oil bath was raised and held at 60 ° C. for 20 minutes. When the obtained contents were observed with an optical microscope, it was confirmed that aggregated particles of about 6.5 μm were formed. The pH is adjusted to 8.0 with an aqueous sodium hydroxide solution, and then the temperature of the heating oil bath is raised to 75 ° C., cooled, filtered, thoroughly washed with ion-exchanged water, dried and dried with a core (1 ) When the particle diameter of the core was measured with a Coulter counter, the 50% D diameter of the body cumulative surgical diameter was 6.5 μm. It was confirmed with an optical microscope that the core particles were spherical.

(Preparation of capsule toner (1))
To 500 parts of the suspension of the core (1) (solid content 10%), 1.5 parts of a polyaluminum chloride 10% aqueous solution is added dropwise with stirring, and then a shell latex solution (solid content 40%) 62. 5 parts were added, pH was adjusted to 4, and stirring was continued for 30 minutes. The suspension was warmed to 55 ° C. and stirred for an additional 3 hours. The obtained toner was filtered, and the wet cake was dried using a flash jet dryer. 84 irregularities of 0.3 μm or more were observed on the surface of the toner.

(Preparation of developer (1))
Around 100 parts of the above toner, 1 part of metatitanic acid (average particle size 40 nm, i-butyltrimethoxysilane treatment) 1 part, silica (average particle diameter 140 nm, HMDS (hexamethyldisilazane) treatment, sol-gel method) 2 parts are surrounded by a Henschel mixer. After blending at a speed of 30 m / s × 15 minutes, coarse particles were removed using a sieve having an opening of 45 μm to obtain an externally added toner. From observation of the FE-SEM photograph of this toner, it was confirmed that silica adhered to the surface of the non-colored composite particles, and the ratio of the non-colored composite particles adhered to the surface of the toner base particles was 8% by number. It was. Further, 100 parts of the carrier and 5 parts of the toner were stirred with a V-blender at 40 rpm × 20 minutes and sieved with a sieve having an opening of 212 μm to obtain developer (1).

[Evaluation of toner and developer]
(Evaluation of low-temperature fixing and gloss characteristics)
The obtained electrophotographic toner is formed on a Fuji Xerox copy paper (platinum mirror coated paper) so that the amount of toner is 0.9 mg / cm ^2, and Color Document-60 (Fuji Xerox Co., Ltd.). The image was fixed with a modified machine manufactured by (manufactured), and the low-temperature fixability was evaluated. In the evaluation, the fixing device temperature was changed from 80 ° C. to 150 ° C. every 10 ° C., and a fixed image was prepared at each fixing temperature. The degree of peeling of the image was observed, and the lowest fixing temperature at which the image hardly peeled off was defined as MFT (° C.) to evaluate the low-temperature fixing property. As a result, the MFT of the electrophotographic toner (1) was 90 ° C. Further, the gloss (60 degrees) obtained by measuring the image fixed at the MFT temperature with the gloss meter was 65 degrees, which is almost the same as that of the paper.

[Evaluation of transferability / developability]
Using the developer (1) using cyan toner, transferability / developability was evaluated by Docu color 1250 (manufactured by Fuji Xerox Co., Ltd.). As a method, a solid patch of 5 × 2 cm is developed, and the developed image on the photosensitive member is measured by tape transfer to measure its weight W ₁ . Next, the same patch is transferred onto paper (J paper, manufactured by Fuji Xerox Office Supply), and the weight W _{2 of the} transferred image is measured. (Transfer efficiency) = W ₂ / W ₁ × 100 (%).
The transfer efficiency was evaluated in an environment of high temperature and high humidity (30 ° C., 80% RH).
-Evaluation of transferability-
○: Transfer efficiency 90% or more Δ: Transfer efficiency 80 to less than 90% ×: Transfer efficiency less than 80%

[Evaluation of cleaning properties]
Using the developer (1), the cleaning property was evaluated by Docu color 1250 (manufactured by Fuji Xerox Co., Ltd.). At this time, the distance from the tip of the sheet metal of the cleaning blade to the tip of the rubber (the amount of protrusion of the rubber) is 10 mm, but it is 7.5 mm, and the length of the sheet metal is increased accordingly. Then, 20,000 copies were taken under low temperature and low humidity (10 ° C., 20% RH), and evaluated whether there was any contamination of the charger due to poor cleaning or image disturbance due to filming on the photoreceptor.
No cleaning failure occurred in 20,000 copies (circle in Table 1 represents this).

<Example 2>
(Production of core (2))
A crystalline latex (2) was produced in the same manner as in Example 1 except that the crystalline polyester (2) was used. The production of the toner was performed in the same manner as in Example 1, and the core (2) was produced.
When the particle size of the core was measured with a Coulter counter, the 50% D diameter of the body cumulative surgical diameter was 6.5 μm. It was confirmed with an optical microscope that the core particles were spherical.
(Preparation of capsule toner (2))
To 715 parts of the suspension of the core (2) (solid content 7%), 1.5 parts of a polyaluminum chloride 10% aqueous solution is added dropwise with stirring, and then 100 parts of a shell latex solution (solid content 40%) is added. , PH was adjusted to 4, and stirring was continued for 30 minutes. The suspension was warmed to 55 ° C. and stirred for an additional 3 hours. The obtained toner was filtered, and the wet cake was dried using a flash jet dryer. 76 irregularities of 0.3 μm or more were observed on the surface of the toner.

(Preparation of developer (3))
Next, external additives were blended in the same manner as in Example 1, and carrier mixing was carried out to obtain a developer (2).
The toner and developer were evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Example 3>
(Production of core (3))
A crystalline latex (3) was produced in the same manner as in Example 1 except that the crystalline polyester (3) was used, and a core (3) was produced in the same manner.
When the particle size of the toner was measured with a Coulter counter, the 50% D diameter of the body cumulative surgical diameter was 6.5 μm. It was confirmed with an optical microscope that the toner was spherical.
(Preparation of capsule toner (3))
To 333 parts of the suspension of core (3) (solid content 15%), 2.0 parts of 10% aqueous solution of polyaluminum chloride is added dropwise with stirring, and then 80 parts of shell latex liquid (solid content 40%) are added. , PH was adjusted to 4, and stirring was continued for 30 minutes. The suspension was warmed to 55 ° C. and stirred for an additional 3 hours. The obtained toner was filtered, and the wet cake was dried using a flash jet dryer. 152 irregularities of 0.3 μm or more were observed on the surface of the toner.

(Preparation of developer (3))
Next, external additives were blended in the same manner as in Example 1, and carrier mixing was performed on this to obtain a developer (3).
The toner and developer were evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Example 4>
(Production of core (4))
A crystalline latex (4) was produced in the same manner as in Example 1 except that the crystalline polyester (4) was used, and a core (4) was produced in the same manner.
When the particle size of the core was measured with a Coulter counter, the 50% D diameter of the body cumulative surgical diameter was 6.5 μm. It was confirmed with an optical microscope that the toner was spherical.
(Preparation of capsule toner (4))
To 250 parts of the core (4) suspension (solid content 20%), 2.0 parts of a polyaluminum chloride 10% aqueous solution is added dropwise with stirring, and then 70 parts of a shell latex liquid (solid content 40%) is added. , PH was adjusted to 4, and stirring was continued for 30 minutes. The suspension was warmed to 55 ° C. and stirred for an additional 3 hours. The obtained toner was filtered, and the wet cake was dried using a flash jet dryer. 230 irregularities of 0.3 μm or more were observed on the surface of the toner.

(Production of developer (4))
Next, external additives were blended in the same manner as in Example 1, and carrier mixing was carried out to obtain a developer (4).
The toner and developer were evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Example 5>
(Production of core (5))
A crystalline latex (5) was produced in the same manner as in Example 1 except that the crystalline polyester (5) was used, and a core (5) was produced in the same manner.
When the particle size of the core was measured with a Coulter counter, the 50% D diameter of the body cumulative surgical diameter was 6.5 μm. It was confirmed with an optical microscope that the toner was spherical.
(Preparation of capsule toner (5))
To 250 parts of the core (5) suspension (solid content 20%), 2.0 parts of a polyaluminum chloride 10% aqueous solution is added dropwise with stirring, and then 70 parts of a shell latex liquid (solid content 40%) is added. , PH was adjusted to 4, and stirring was continued for 30 minutes. The suspension was warmed to 55 ° C. and stirred for an additional 3 hours. The obtained toner was filtered, and the wet cake was dried using a flash jet dryer. 204 irregularities of 0.3 μm or more were observed on the surface of the toner.

(Preparation of developer (5))
Next, external additives were blended in the same manner as in Example 1, and carrier mixing was carried out to obtain a developer (5).
The toner and developer were evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 1>
(Preparation of capsule toner (6))
0.75 part of a 10% aqueous solution of polyaluminum chloride is added dropwise to 250 parts of the suspension of the core (4) (solids 20%) with stirring, and then 25 parts of a shell latex solution (solids 40%). The pH was adjusted to 3 and stirring was continued for 30 minutes. The suspension was warmed to 55 ° C. and stirred for an additional 3 hours. The obtained toner was filtered, and the wet cake was dried using a flash jet dryer. No irregularities of 0.3 μm or more were observed on the toner surface.

(Production of developer (6))
Next, external additives were blended in the same manner as in Example 1, and carrier mixing was performed thereon to obtain a developer (6).
The toner and developer were evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative example 2>
(Production of core (7))
An amorphous latex (1) was produced in the same manner as in Example 1 except that the amorphous polyester (1) was used. The core was produced in the same manner as in Example 1 to produce the core (7).
When the particle size of the core was measured with a Coulter counter, the 50% D diameter of the body cumulative surgical diameter was 6.5 μm. It was confirmed with an optical microscope that the core particles were spherical.
(Preparation of capsule toner (7))
To 250 parts of the suspension of the core (7) (solid content 20%), 0.75 part of a 10% polyaluminum chloride aqueous solution is added dropwise with stirring, and then 25 parts of a shell latex solution (solid content 40%) is added. , PH was adjusted to 3, and stirring was continued for 30 minutes. The suspension was warmed to 55 ° C. and stirred for an additional 3 hours. The obtained toner was filtered, and the wet cake was dried using a flash jet dryer. No irregularities of 0.3 μm or more were observed on the toner surface.

(Preparation of developer (7))
Next, external additives were blended in the same manner as in Example 1, and carrier mixing was carried out to obtain a developer (7).
The toner and developer were evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 3>
(Production of core (8))
An amorphous latex (2) was produced in the same manner as in Example 1 except that the amorphous polyester (2) was used, and a core (8) was produced in the same manner as in Example 1.
When the particle size of the core was measured with a Coulter counter, the 50% D diameter of the body cumulative surgical diameter was 6.5 μm. It was confirmed with an optical microscope that the core particles were spherical.
(Preparation of capsule toner (8))
To 250 parts of the suspension of the core (8) (solid content 20%), 2.0 parts of a 10% aqueous solution of polyaluminum chloride is added dropwise with stirring, and then 70 parts of a shell latex solution (solid content 40%) is added. , PH was adjusted to 4, and stirring was continued for 30 minutes. The suspension was warmed to 55 ° C. and stirred for an additional 3 hours. The obtained toner was filtered, and the wet cake was dried using a flash jet dryer. On the surface of the toner, 180 irregularities of 0.3 μm or more were observed.

(Production of developer (8))
Next, external additives were blended in the same manner as in Example 1, and carrier mixing was carried out to obtain a developer (8).
The toner and developer were evaluated in the same manner as in Example 1. The results are shown in Table 1.

As shown in Table 1, the toners (1) to (5) of the present invention have low-temperature fixability (90 ° C.) and can form images having high gloss (gloss 60 to 70). The developer of the present invention has good cleaning properties without impairing transferability.
On the other hand, even in the example using the crystalline resin (Comparative Example 1), the developer using the toner having no unevenness on the surface has poor cleaning properties. In addition, the toner using the non-crystalline resin (Comparative Examples 2 and 3) cannot be fixed at low temperature, and the gloss of the image fixed at 130 ° C. or 140 ° C. (MFT) is not high.

Claims (3)

  An electrophotographic toner containing a binder resin and a colorant and having a core-shell structure, wherein the core mainly contains a crystalline resin, the shell is 15% by mass or more and 120% by mass or less with respect to the core. An electrophotographic toner having hemispherical protrusions having a step of 0.3 μm or more and having a shell produced by an emulsion aggregation method.   A fine particle dispersion of a shell-forming resin is mixed with a dispersion of a core containing a binder resin mainly composed of a crystalline resin and a colorant, and the fine particles of the shell-forming resin are adhered and aggregated on the core surface. 2. A method for producing an electrophotographic toner according to 1.   An electrophotographic developer containing a toner and a carrier, wherein the toner contains a binder resin and a colorant, the core mainly contains a crystalline resin, and the shell is 15% by mass or more and 120% by mass with respect to the core. %, The shell has hemispherical protrusions with a step of 0.3 μm or more, and the shell is produced by an emulsion aggregation method.