JP2020134606A - Electrostatic latent image developing toner and two-component developer - Google Patents

Abstract

To provide an electrostatic latent image developing toner that features minimized scattering during development, and a two-component developer produced using the same.SOLUTION: An electrostatic latent image developing toner of the present invention comprises toner base particles covered with an external additive, where the external additive contains magnesium silicate particles and alumina particle, the magnesium silicate particles having an average diameter in a range of 20 to 100 nm.SELECTED DRAWING: None

Description

The present invention relates to a toner for electrostatic latent image development and a two-component developer, and more particularly to a toner for electrostatic latent image development capable of suppressing scattering during development and a two-component developer using the same.

In recent years, oilless fixing color toner has been used to eliminate the need to apply silicone oil to the heating roller in the fixing process of the electrophotographic image forming process and to eliminate white streak noise generated by dust adhering to the optical system due to oil vapor. It is used. However, the oilless fixing color toner needs to use a mold release agent as an essential component, and when the softening point of the wax of the mold release agent is lower than 60 ° C., the effect of improving the high temperature offset property is reduced and the temperature is higher than 100 ° C. In this case, there is a problem that the dispersion in the binder resin is insufficient and the filming on the photoconductor is likely to occur.

As a means of suppressing the filming of the oilless fixing color toner to the member, not only the formulation design of the toner matrix particles that suppresses the release of wax and other toner additives that are the causative substances of the filming, but also the filming substance. Measures such as external addition of a polishing substance to the surface of toner particles for removing the above-mentioned substances and external addition of a lubricating substance for preventing the filming substance from adhering to the member are being studied.

MgO / SiO _2- based composite oxides generally called forsterite, steatite, and enstatite are effective in preventing filming during cleaning, have properties similar to alumina such as high thermal expansion, and are dielectrics in the high frequency region. It is a material that has excellent characteristics and insulation resistance at high temperatures, and has been used as ceramics for electronic parts for a long time.

However, since the conventional MgO / SiO _2- based composite oxide powder exceeds 0.2 μm even if the average primary particle size is small and the average secondary particle size is 2 to 3 μm or more, it was added to the toner for electrophotographic. In this case, there are problems such as poor dispersibility on the toner surface, adversely affecting the chargeability of the toner, and damage to the photoconductor due to the large particle size, and there is a problem in application to the toner.

The toner described in Patent Document 1 has a smaller particle size distribution than the conventional MgO / SiO _2- based composite oxide powder (magnesium silicate particles), and is adjusted to the particle size range described in Patent Document 1. By using the above-mentioned MgO / SiO _2- based composite oxide, it is possible to solve the problem of dispersibility on the toner surface and the problem of scratches on the members, which have been problems with the above-mentioned conventional magnesium silicate. became.

However, on the other hand, since the magnesium silicate particles having a smaller particle size tend to aggregate with each other, they are separated from the toner by stress in the developing machine and softly aggregate during low printing. The presence of these softly agglomerated particles deteriorates the fluidity of the developer in the developing machine, and if switching to high-print printing in such a state, the mixing property with the replenished toner is poor, and thus the toner scatters. There was a problem that it got worse.

JP-A-2007-218941

The present invention has been made in view of the above problems and situations, and the problem to be solved is to use a toner for electrostatic latent image development capable of suppressing scattering during development and a two-component developer using the same. Is to provide.

In order to solve the above problems, the present inventor should simultaneously contain hard alumina particles as an external additive in the toner for electrostatic latent image development in the process of examining the cause of the above problems. As a result, we have found that it is possible to suppress the scattering property during development, and have reached the present invention.
That is, the above problem according to the present invention is solved by the following means.

1. 1. A toner for electrostatic latent image development having an external additive on the surface of the toner matrix particles, wherein the external agent contains magnesium silicate particles and alumina particles, and the average particle size of the magnesium silicate particles is 20 to 100 nm. Toner for electrostatic latent image development, which is characterized by being within the range of.

2. 2. The toner for electrostatic latent image development according to item 1, wherein the average particle size of the magnesium silicate particles is larger than the average particle size of the alumina particles.

3. 3. The toner for electrostatic latent image development according to the first or second item, wherein the average particle size of the alumina particles is in the range of 10 to 50 nm.

4. Two-component development characterized by containing the toner for electrostatic latent image development according to any one of the items 1 to 3 and a carrier having a resin coating of an alicyclic methacrylate monomer polymer. Agent.

According to the above means of the present invention, it is possible to provide a toner for electrostatic latent image development capable of suppressing scattering during development and a two-component developer using the toner.
Although the mechanism of expression or mechanism of action of the effect of the present invention has not been clarified, it is inferred as follows.

As an external additive, alumina particles harder than magnesium silicate particles are simultaneously contained in the electrostatic latent image developing toner, so that they are desorbed from the electrostatic latent image developing toner due to stress in the developing machine and softly aggregated. It is presumed that this is because the particles can be crushed. In particular, it is presumed that the deterioration of the fluidity of the developing agent at the time of low printing, which has been a problem when magnesium silicate particles having a smaller particle size are used as an external additive, can be suppressed. Therefore, it is presumed that the scattering property during development is suppressed.

At this time, if the average particle size of the magnesium silicate particles exceeds 100 nm, the fluidity of the developer when it adheres to the electrostatic latent image developing toner cannot be maintained, which is not preferable. Further, if it is less than 20 nm, it is not preferable because it cannot be crushed even if it is softly aggregated.

The electrostatic latent image developing toner of the present invention is an electrostatic latent image developing toner having an external additive on the surface of the toner matrix particles, wherein the external additive contains magnesium silicate particles and alumina particles, and the above-mentioned The average particle size of the magnesium silicate particles is in the range of 20 to 100 nm.

This feature is a technical feature common to or corresponding to each of the following embodiments (forms).
In an embodiment of the present invention, it is preferable that the average particle size of the magnesium silicate particles is larger than the average particle size of the alumina particles, because the hard alumina can suppress damage to the photoconductor.
Further, when the average particle size of the alumina particles is in the range of 10 to 50 nm, fluidity to the toner can be imparted as an external additive and polishing power is suppressed, so that high durability due to suppression of photoconductor wear is achieved. It is preferable from the viewpoint that the conversion can be achieved.
Further, the inclusion of the toner for electrostatic latent image development of the present invention and the carrier having a resin coating of the alicyclic methacrylate monomer polymer causes an impact when the toner and the carrier collide with each other due to the cyclic alkyl group unit. It is preferable because it softens and suppresses the desorption of magnesium silicate particles from the toner.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, "~" is used to mean that the numerical values described before and after the value are included as the lower limit value and the upper limit value.

<< Toner for electrostatic latent image development >>
The electrostatic latent image developing toner of the present invention is an electrostatic latent image developing toner having an external additive on the surface of the toner matrix particles, wherein the external additive contains magnesium silicate particles and alumina particles, and the above-mentioned The average particle size of the magnesium silicate particles is in the range of 20 to 100 nm.

The toner for electrostatic latent image development of the present invention (hereinafter, also simply referred to as toner) is an aggregate of toner particles. The toner particles contain magnesium silicate particles and alumina particles as an external additive on the surface of the toner matrix particles. The toner matrix particles have a binder resin. Further, if necessary, a known additive may be contained.

[External agent]
The external additive is used for toner particles for the purpose of improving fluidity, chargeability and cleanability. In the present invention, magnesium silicate particles and alumina particles are included as an external additive. As an external additive. By simultaneously containing alumina particles harder than magnesium silicate in the toner for electrostatic latent image development, it was a problem especially when magnesium silicate particles having a smaller particle size were used as an external additive. It is possible to suppress the scattering property at the time of printing.

The particle size of the magnesium silicate particles is preferably larger than the average particle size of the alumina particles. It is preferable that the hard alumina particles enter the gaps between the larger magnesium silicate particles, which reduces the chance of contact between the alumina particles and the photoconductor and suppresses damage to the photoconductor by the alumina particles.

The average particle size of the alumina particles is preferably in the range of 10 to 50 nm. When the average particle size of the alumina particles is 10 nm or more, it is preferable because it can impart fluidity to the toner as an external additive. If it is 50 nm or less, the polishing force is suppressed, so that high durability can be achieved by suppressing wear of the photoconductor, the number of times the photoconductor is replaced is reduced, and the environmental load is reduced, which is preferable.

As the external additive according to the present invention, the average particle size of the magnesium silicate particles and the alumina particles can be obtained from the electron microscope image of each particle. That is, a scanning electron microscope image is taken, the photographic image is captured by a scanner, and binarized using an image processing analyzer LUZEX AP (manufactured by Nireco Co., Ltd.) to obtain one type of magnesium silicate particles and alumina. The horizontal ferret diameter of 100 particles per particle was calculated, and the number average primary particle diameter was taken as the average particle diameter.

The average particle size of the magnesium silicate particles contained as an external additive is measured in a state before being externally added to the toner population particles, and is measured as the average of the magnesium silicate particles contained in the toner population particles as an external additive. It may be regarded as a particle size.
The measurement at that time can be performed in the same manner as the measurement of the average particle size of the magnesium silicate particles in the toner.

<Magnesium silicate particles>
The average particle size of the magsium silicate particles used in the present invention is in the range of 20 to 100 nm. If the average particle size of the magnesium silicate particles exceeds 100 nm, the fluidity of the developer when it adheres to the electrostatic latent image developing toner cannot be maintained, which is not preferable. Further, if it is less than 20 nm, it is not preferable because it cannot be crushed even if it is softly aggregated.
The magnesium silicate particles can be used without particular limitation as long as they have the above average particle size. Further, it is preferable that the average particle size of the magnesium silicate particles is larger than the average particle size of the alumina particles. By doing so, the hard alumina particles enter the gaps between the larger magnesium silicate particles, so that the chances of the alumina in contact with the photoconductor are reduced and scratches can be suppressed, which is preferable.
Magnesium silicate particles can be produced by a known production method. For example, the method described in Japanese Patent Application Laid-Open No. 2003-327470 can be mentioned. This production method is preferable in that magnesium silicate particles are a fine particle type and have a uniform chemical composition.

<Alumina particles>
Alumina particles contain aluminum oxide represented by Al ₂ O ₃ , and aluminum oxide is known to have α-type, γ-type, σ-type, or a mixture thereof, and its crystal system as a shape. From cubic to spherical under the control of.
The alumina particles used in the present invention are preferably smaller than the magnesium silicate particles. The average particle size of the alumina particles is preferably in the range of 10 to 50 nm.
Alumina can be produced by a known method. The Bayer method is generally used as a method for producing alumina, but in order to obtain high-purity and nano-sized alumina, a hydrolysis method (manufactured by Sumitomo Chemical Industry Co., Ltd.), a gas phase synthesis method (manufactured by CI Kasei), and flame water addition are used. The decomposition method (manufactured by Nippon Aerosil), the underwater spark discharge method (manufactured by Iwatani Chemical Industry), etc. can be mentioned.

<Degree of hydrophobicity of alumina particles>
The surface of the alumina is preferably surface-modified, and the degree of hydrophobicity is preferably in the range of 40 to 70% by volume. By doing so, it is possible to suppress fluctuations due to environmental differences and fluctuations in the amount of charge when shifting to carriers. Further, the release rate of the surface modifier when the surface is modified is preferably 0% by mass. In the presence of the liberated surface modifier, it migrates to the carrier and the charge amount fluctuation becomes large.
The release rate can be measured by the following quantitative methods (1) to (3).
(1) The target extraction sample is immersed in chloroform, stirred, and left to stand. Chloroform is newly added to the solid content after removing the supernatant by centrifugation, and the mixture is stirred and left to stand. Repeat this operation to remove free matter.
(2) Quantification of carbon amount The carbon amount was quantified by a CHN elemental analyzer (CHN coder MT-5 type (manufactured by Yanako)).
(3) The release rate was calculated by the following formula.
Free rate = (C _0- C ₁ ) / C ₀ x 100 (%)
C ₀ : Amount of carbon in the sample before the extraction operation C ₁ : Amount of carbon in the sample after the extraction operation

(Measurement of hydrophobicity)
The degree of hydrophobicity can be determined by measuring as follows using a powder wettability tester (WET-101P; manufactured by Reska Co., Ltd.).

In a laboratory environment, a stirrer chip having a length of 20 mm and 60 mL of ion-exchanged water at 25 ° C. are placed in a 200 mL tall beaker and set in a powder wettability tester (WET-101P; manufactured by Reska Co., Ltd.). 50 mg of alumina was floated on the ion-exchanged water, the lid and the methanol supply nozzle were immediately set, and the measurement was started at the same time as the stirrer stirring was started. The supply rate of methanol (methanol special grade; manufactured by Kanto Chemical Co., Inc.) was 2.0 mL / min, and the measurement time was 70 minutes. The stirring speed of the stirrer is 380 to 420 rpm. The toner initially floats on the interface of the ion-exchanged water, but as the methanol concentration increases, it gradually gets wet with the mixed solution of the ion-exchanged water and methanol and disperses in the liquid. As a result, the light transmittance of the liquid gradually decreases. From the obtained data, the horizontal axis plots the methanol concentration (vol%) calculated from the amount of methanol supplied (mL), and the vertical axis plots the light transmittance (voltage ratio) (%), and the light transmittance is the maximum value. The methanol volume concentration (%) when it is between the minimum value and the minimum value can be defined as the "hydrophobicity (volume%)".

(Surface modification method)
As the surface modifier of the alumina particles, a general coupling agent, silicone oil, fatty acid, fatty acid metal salt and the like can be used, but a silane compound and silicone oil are preferable.

Examples of the silane compound include chlorosilane, alkoxysilane, silazane, and a special silylating agent. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, Methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N-bis (Trimethylsilyl) urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ -Glysidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane can be exemplified as typical examples.
The surface modifier used in the present invention is particularly preferably isobutyltrimethoxysilane and octyltrimethoxysilane.

Specific examples of the silicone oil include, for example, an organosiloxane oligomer, octamethylcyclotetrasiloxane, a cyclic compound such as decamethylcyclopentasiloxane, tetramethylcyclotetrasiloxane, and tetravinyltetramethylcyclotetrasiloxane, or a linear or linear silicone oil. Branched organosiloxanes can be mentioned. Further, a highly reactive silicone oil having a modifying group introduced into the side chain, one end, both ends, one end of the side chain, both ends of the side chain, or the like may be used. Examples of the type of the modifying group include, but are not limited to, alkoxy, carboxy, carbinol, higher fatty acid modification, phenol, epoxy, methacryl, amino and the like. Further, for example, a silicone oil having several kinds of modifying groups such as amino / alkoxy modification may be used. Further, dimethyl silicone oil, these modified silicone oils, and other surface modifiers may be mixed or used in combination. Examples of the treatment agent to be used in combination include a silane coupling agent, a titanate-based coupling agent, an aluminate-based coupling agent, various silicone oils, fatty acids, fatty acid metal salts, esterified products thereof, rosinic acid and the like. ..

As a surface modification method, for example, a dry method such as a spray-drying method in which a treatment agent or a solution containing the treatment agent is sprayed on the particles suspended in the gas phase, or the particles are immersed in a solution containing the treatment agent. Examples thereof include a wet method of drying and a mixing method of mixing a treatment agent and particles with a mixer.

<Other external additives>
The toner of the present invention may further contain other known external additives as an external additive as long as the effects of the present invention are not impaired. Examples of the external additive include inorganic oxide fine particles such as silica fine particles and titanium oxide fine particles, inorganic stearic compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles, and strontium titanate and zinc titanate. Inorganic titanic compound fine particles and the like can be mentioned. These inorganic fine particles are subjected to gloss treatment, surface modification, etc. with a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, etc. in order to improve heat-resistant storage property and environmental stability. May be good.

Furthermore, organic fine particles may also be used as other external additives. As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. Specifically, homopolymers such as styrene and methylmethacrylate and organic fine particles obtained from these copolymers can be used.

Lubricants can also be used as an external additive. Lubricants are used for the purpose of further improving cleanability and transferability, and specifically, salts such as zinc stearate, aluminum, copper, magnesium and calcium, zinc oleate and manganese. , Salts such as iron, copper and magnesium, salts such as zinc palmitate, copper, magnesium and calcium, salts such as zinc linoleic acid and calcium, metal salts of higher fatty acids such as zinc ricinolic acid and salts such as calcium. Can be mentioned.

[Toner matrix particles]
The toner matrix particles contain a setting resin, and may also contain other constituent components such as a colorant, a mold release agent (wax), and a charge control agent, if necessary.

<Bundling resin>
The binder resin contained in the toner matrix particles preferably contains an amorphous resin as well as a crystalline resin.
(Amorphous resin)
Amorphous resin is a resin that does not have a melting point and has a relatively high glass transition temperature (Tg) when differential scanning calorimetry (DSC) is performed on the resin. The glass transition temperature (Tg) of the amorphous resin is not particularly limited, but is 25 to 60 ° C. from the viewpoint of surely obtaining fixability such as low temperature fixability and heat resistance such as heat storage resistance and blocking resistance. Is preferable. In the present specification, the glass transition temperature (Tg) of the resin adopts the value measured by the method described in the examples.

The amorphous resin is not particularly limited as long as it has the above-mentioned characteristics, and a conventionally known amorphous resin in the present technology can be used. Specific examples thereof include vinyl resin, urethane resin, urea resin, and amorphous polyester resin. Of these, vinyl resin is preferable because it is easy to control the thermoplasticity.

The vinyl resin is not particularly limited as long as it is a polymer of a vinyl compound, and examples thereof include (meth) acrylic acid ester resin, styrene- (meth) acrylic acid ester resin, and ethylene-vinyl acetate resin. One of these may be used alone, or two or more thereof may be used in combination.

(Styrene- (meth) acrylic ester resin)
Among the above vinyl resins, a styrene- (meth) acrylic acid ester resin is preferable in consideration of plasticity at the time of heat fixing. Therefore, the styrene- (meth) acrylic acid ester resin (hereinafter, also referred to as “styrene- (meth) acrylic resin”) as the amorphous resin will be described below.

The styrene- (meth) acrylic resin is formed by addition polymerization of at least a styrene monomer and a (meth) acrylic acid ester monomer. The styrene monomer referred to here includes a structure having a known side chain or functional group in the styrene structure, in addition to the styrene represented by the structural formula of CH ₂ = CH-C ₆ H ₅ . Further, the (meth) acrylic acid ester monomer referred to here is an acrylic acid ester derivative or a methacrylic acid ester derivative in addition to the acrylic acid ester or methacrylic acid ester represented by CH ₂ = CHCOOR (R is an alkyl group). Etc., which contain an ester having a known side chain or functional group in the structure. In the present specification, "(meth) acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer".

An example of a styrene monomer and a (meth) acrylic acid ester monomer capable of forming a styrene- (meth) acrylic resin is shown below.
Specific examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, and 2,4-dimethylstyrene. , P-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene and the like. These styrene monomers can be used alone or in combination of two or more.

Specific examples of the (meth) acrylic acid ester monomer include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate. , Acrylate esters such as stearyl acrylate, lauryl acrylate, phenyl acrylate; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, Examples thereof include methacrylic acid esters such as stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate and dimethylaminoethyl methacrylate. These (meth) acrylic acid ester monomers can be used alone or in combination of two or more.

The content of the structural unit derived from the styrene monomer in the styrene- (meth) acrylic resin is preferably in the range of 50 to 90% by mass with respect to the total amount of the resin. When the content of the styrene- (meth) acrylic resin is 50% by mass or more, the dispersibility of the colorant in the toner is improved, so that a higher image density can be realized.
The content of the structural unit derived from the (meth) acrylic acid ester monomer in the resin is preferably 10 to 60% by mass with respect to the total amount of the resin.
Further, the styrene- (meth) acrylic resin may contain the following monomer compounds in addition to the above styrene monomer and (meth) acrylic acid ester monomer.

Examples of such monomer compounds include compounds having a carboxy group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, silicic acid, fumaric acid, maleic acid monoalkyl ester, and itaconic acid monoalkyl ester; 2-Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl ( Examples thereof include compounds having a hydroxy group such as meta) acrylate. These monomer compounds can be used alone or in combination of two or more.
The content of the structural unit derived from the above-mentioned monomer compound in the styrene- (meth) acrylic resin is preferably 0.5 to 20% by mass with respect to the total amount of the resin.

The weight average molecular weight (Mw) of the styrene- (meth) acrylic resin is preferably 1000 to 100,000. The method for producing the styrene- (meth) acrylic resin is not particularly limited, and any polymerization initiator such as peroxide, persulfide, persulfate, and azo compound usually used for the polymerization of the above-mentioned monomer is used. , Bulk polymerization, solution polymerization, emulsion polymerization method, mini-emulsion method, dispersion polymerization method and other known polymerization methods. In addition, a commonly used chain transfer agent can be used for the purpose of adjusting the molecular weight. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptans such as n-octyl mercaptan and mercapto fatty acid esters.

The content of the amorphous resin in the binder resin is not particularly limited, but is preferably more than 50% by mass, more preferably 70% by mass or more, and 90% by mass, based on the total amount of the binder resin. % Or more is particularly preferable. On the other hand, the upper limit of the content is not particularly limited and is 100% by mass or less.

(Amorphous polyester resin)
The amorphous polyester resin is a non-crystalline polyester resin obtained by a polymerization reaction of a divalent or higher carboxylic acid (polyvalent carboxylic acid) monomer and a divalent or higher alcohol (polyhydric alcohol) monomer. It is a resin that exhibits crystallinity. An amorphous polyester resin can be formed by polymerizing (esterifying) a polyvalent carboxylic acid monomer and a polyhydric alcohol monomer, which will be described later, using a known esterification catalyst.

The polyvalent carboxylic acid monomer is a compound containing two or more carboxy groups in one molecule.
The polyvalent carboxylic acid monomer that can be used for the synthesis of the amorphous polyester resin is not particularly limited, and known ones can be used. For example, the same ones that can be used for the amorphous polyester polymerized segment are used. it can.

A polyhydric alcohol monomer is a compound containing two or more hydroxy groups in one molecule.
The polyhydric alcohol monomer that can be used for synthesizing the amorphous polyester resin is not particularly limited, and known ones can be used.
The esterification catalyst that can be used is not particularly limited, and known esterification catalysts can be used.

The polymerization temperature is not particularly limited, but is preferably in the range of 150 to 250 ° C. The polymerization time is not particularly limited, but is preferably in the range of 0.5 to 10 hours. During the polymerization, the pressure inside the reaction system may be reduced, if necessary.

The glass transition point (T _g ) of the amorphous resin is preferably 25 to 60 ° C., more preferably 35 to 55 ° C. from the viewpoint of achieving both sufficient low-temperature fixability and heat-resistant storage property.
The weight average molecular weight (Mw) of the amorphous polyester resin can be in the range of 1000 to 100,000.

When the acid value of the amorphous polyester resin is smaller than the acid value of the crystalline polyester resin, the dispersibility of the crystalline polyester resin can be sufficiently enhanced, which is preferable.
The acid value of the amorphous polyester resin can be measured according to the method (potentiometric titration method) described in JIS K0070-1992. In the measurement, the solvent used is a mixture of tetrahydrofuran and isopropyl alcohol at a volume ratio of 1: 1.

(Crystallinity resin)
It is preferable to use a crystalline polyester resin as the crystalline resin.
The crystalline polyester resin is one of the binding resins, and any known crystalline polyester resin can be used as long as it is a crystalline polyester resin. Showing crystallinity means having a clear endothermic peak at the melting point, that is, when the temperature rises, in the endothermic curve obtained by DSC. A clear endothermic peak means a peak having a half-value width within 15 ° C. in the endothermic curve when the temperature is raised at a rate of 10 ° C./min.

From the viewpoint of obtaining excellent low-temperature fixability, the content of the crystalline polyester resin in the toner particles is preferably in the range of 1 to 30% by mass, and preferably in the range of 5 to 20% by mass. More preferred.
If the content is 1% by mass or more, sufficient low-temperature fixability can be obtained, and if it is 30% by mass or less, scattering of toner due to a decrease in chargeability can be suppressed.

Specifically, the crystalline polyester resin is a polyester resin obtained by a polymerization reaction of a divalent or higher carboxylic acid (polyvalent carboxylic acid) monomer and a divalent or higher alcohol (polyhydric alcohol) monomer. Among them, a resin showing crystallinity.
The crystalline polyester resin is a polyvalent carboxylic acid monomer and a polyhydric alcohol that can be used in the synthesis of the crystalline polyester resin described later by utilizing a known esterification catalyst in the same manner as the above-mentioned amorphous polyester resin. It can be formed using a metric.

Examples of the polyvalent carboxylic acid monomer that can be used for synthesizing a crystalline polyester resin include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecylsuccinic acid, and 1,10-decandicarboxylic acid. Saturated aliphatic dicarboxylic acids such as acids (dodecanedioic acid) and 1,12-dodecanedicarboxylic acid (tetradecanedioic acid); alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; aromatics such as phthalic acid, isophthalic acid and terephthalic acid. Dicarboxylic acids; trivalent or higher valent carboxylic acids such as trimellitic acid and pyromellitic acid; anhydrides of these carboxylic acid compounds, alkyl esters having 1 to 3 carbon atoms and the like can be mentioned.
These may be used individually by 1 type and may be used in combination of 2 or more type.

Examples of the polyhydric alcohol monomer that can be used in the synthesis of the crystalline polyester resin include 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6. Aliphatic diols such as −hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 1,4-butenediol; glycerin, pentaerythritol, trimethylolpropane, Examples thereof include trihydric or higher polyhydric alcohols such as sorbitol.
These may be used individually by 1 type and may be used in combination of 2 or more type.

(Hybrid crystalline polyester resin)
The crystalline polyester resin is preferably a hybrid resin of a crystalline polyester resin and an amorphous resin.
Such a hybrid crystalline polyester resin can be adjusted in affinity with the amorphous resin so that the crystalline resin is uniformly finely dispersed in the amorphous resin.

In the hybrid crystalline polyester resin, a resin portion having a structure derived from a crystalline poeryster resin is referred to as a crystalline polyester resin segment, and a resin portion having a structure derived from an amorphous resin is referred to as an amorphous resin segment.
Since the hybrid crystalline polyester resin has a high affinity with the amorphous resin in which the amorphous resin segment is a matrix phase, the molecular chains of the crystalline resin segment can be easily arranged and exhibit sufficient crystallinity. it can.

<Colorant>
As the colorant, carbon black, a magnetic substance, a dye, a pigment or the like can be arbitrarily used, and as the carbon black, channel black, furnace black, acetylene black, thermal black, lamp black or the like is used. As the magnetic material, a ferromagnetic metal such as iron, nickel, or cobalt, an alloy containing these metals, a ferrite, or a compound of a ferromagnetic metal such as magnetite can be used.

As a dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95 and the like can be used, and mixtures thereof can also be used. As a pigment, C.I. I. Pigment Red 5, 48: 1, 48: 3, 53: 1, 57: 1, 81: 4, 122, 139, 144, 149, 166, 177, 178, 222, C.I. I. Pigment Orange 31, 43, C.I. I. Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, C.I. I. Pigment Green 7, C.I. I. Pigment Blue 15: 3, 15: 4, 60, etc. can be used, and mixtures thereof can also be used.

<Release agent>
As the release agent, various known waxes can be used. Examples of the wax include polyolefin waxes such as polyethylene wax and polypropylene wax, branched chain hydrocarbon waxes such as microcrysterin wax, long chain hydrocarbon waxes such as paraffin wax and sazole wax, and dialkyls such as distearyl ketone. Ketone wax, carnauba wax, montan wax, behenate behenate, trimethylpropantribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol di Examples thereof include ester waxes such as stearate, tristearyl trimellitic acid and distealyl maleate, and amide waxes such as ethylenediaminebehenylamide and tristealylamide trimellitic acid. The content of the release agent is preferably 0.1 to 30 parts by mass, and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the binder resin. These can be used alone or in combination of two or more. The melting point of the release agent is preferably 50 to 95 ° C. from the viewpoint of low temperature fixability and releasability of the toner in electrophotographic.

<Charge control material>
Charge control agent As the charge control agent constituting the particles, various known charge control agents that can be dispersed in an aqueous medium can be used. Specific examples thereof include niglosin dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylate metal salts, and metal complexes thereof.

[Manufacturing method of toner for electrostatic latent image development]
The method for producing the toner of the present invention is not particularly limited, and examples thereof include known methods such as a kneading and pulverizing method, a suspension polymerization method, an emulsion aggregation method, a dissolution suspension method, a polyester elongation method, and a dispersion polymerization method.
Among these, it is preferable to adopt the emulsification / aggregation method from the viewpoint of particle size uniformity and shape controllability.

(Emulsification aggregation method)
The emulsion aggregation method is a dispersion of binder resin particles (hereinafter, also referred to as “binding resin particles”) dispersed by a surfactant or a dispersion stabilizer, and, if necessary, colorant particles (hereinafter, also referred to as “bonding resin particles”). , Also referred to as "colorant particles"), agglomerate until the desired toner particle size is obtained, and further fuse the binder resin particles to control the shape to produce toner particles. How to do it. Here, the particles of the binder resin may optionally contain a mold release agent, a charge control agent, and the like.

As a preferable method for producing the toner according to the present invention, an example of obtaining toner particles having a core-shell structure by using an emulsion aggregation method is shown below.
(1) Step of preparing a colorant particle dispersion liquid in which colorant particles are dispersed in an aqueous medium (2) Bundling resin particles containing an internal additive are dispersed in the aqueous medium, if necessary. Step of preparing the resin particle dispersion (core / shell resin particle dispersion) (3) The colorant particle dispersion and the core resin particle dispersion are mixed to obtain a coagulation resin particle dispersion. A step of aggregating and fusing colorant particles and binder resin particles in the presence of a coagulant to form agglomerated particles as core particles (aggregation / fusion step).
(4) The shell resin particle dispersion containing the shell layer binding resin particles is added to the dispersion containing the core particles, and the shell layer particles are aggregated and fused to the core particle surface to form the core. -Step of forming toner matrix particles with shell structure (aggregation / fusion step)
(5) A step of filtering out the toner matrix particles from the toner matrix particle dispersion (toner matrix particle dispersion) and removing the surfactant and the like (cleaning step).
(6) Step of drying toner matrix particles (drying step)
(7) Step of adding an external additive to the toner matrix particles (external agent treatment step)

Toner particles having a core-shell structure are first prepared by aggregating and fusing the binder resin particles for the core particles and the colorant particles, and then for the shell layer in the dispersion liquid of the core particles. It can be obtained by adding the binding resin particles of the above to agglomerate and fuse the binding resin particles for the shell layer on the surface of the core particles to form a shell layer covering the surface of the core particles. However, for example, in the step (4) above, toner particles formed from single-layer particles can be similarly produced without adding the resin particle dispersion for shell.

[Two-component developer]
The toner of the present invention can be used as a magnetic or non-magnetic one-component developer, but is preferably mixed with a carrier and used as a two-component developer.
When the toner is used as a two-component developer, the carrier preferably contains a carrier obtained by coating the surface of the core material particles with a coating resin. Specifically, the carrier used in the two-component developer of the present invention is preferably a carrier having a resin coating of an alicyclic methacrylate monomer polymer.

(Core particle)
The core material particles constituting the carrier particles are composed of, for example, metal powder such as iron powder and various ferrites. Of these, ferrite is preferred.
As the ferrite, a ferrite containing a heavy metal such as copper, zinc, nickel and manganese, and a light metal ferrite containing an alkali metal or an alkaline earth metal are preferable.
Ferrite is a compound represented by the formula: (MO) _x (Fe ₂ O ₃ ) _y , and the molar ratio y of Fe ₂ O ₃ constituting the ferrite is preferably 30 to 95 mol%. Ferrite having a composition ratio y in the above range has an advantage that it is easy to obtain a desired magnetization, so that carriers that are less likely to cause carrier adhesion can be produced. M in the formula is manganese (Mn), magnesium (Mg), strontium (Sr), calcium (Ca), titanium (Ti), copper (Cu), zinc (Zn), nickel (Ni), aluminum (Al). , Silicon (Si), Zirconium (Zr), Bismuth (Bi), Cobalt (Co), Lithium (Li) and other metal atoms, which can be used alone or in combination of two or more.

The volume average particle diameter of the core material particles is generally in the range of 10 to 500 μm, preferably in the range of 30 to 100 μm.
The volume average particle size (D ₅₀ ) of the core material particles can be measured by a wet method using a laser diffraction type particle size distribution measuring device “HEROS KA” (manufactured by Nippon Laser Co., Ltd.). Specifically, first, an optical system having a focal position of 200 mm is selected, and the measurement time is set to 5 seconds. Then, the magnetic particles for measurement are added to a 0.2 mass% sodium dodecyl sulfate aqueous solution and dispersed for 3 minutes using an ultrasonic cleaner "US-1" (manufactured by AS ONE Corporation) to prepare a sample dispersion for measurement. It is prepared, a few drops of this are supplied to "HEROS KA", and measurement is started when the sample concentration gauge reaches the measurable range. A cumulative distribution is created from the small diameter side of the obtained particle size distribution with respect to the particle size range (channel), and the particle size with a cumulative total of 50% is defined as the volume average particle size (D ₅₀ ).

(Coating resin)
The coating resin according to the present invention preferably has a resin film of an alicyclic methacrylate monomer polymer. The presence of the cyclic alkyl group unit, that is, the presence of a bulky part in a part of the molecule, softens the impact when the toner and the carrier collide with each other, thus suppressing the desorption of magnesium silicate particles from the toner. Because it can be done.

The alicyclic methacrylate monomer preferably has a cycloalkyl group having 5 to 8 carbon atoms, and specific examples thereof include cyclopentyl methacrylate, cyclohexyl methacrylate, cycloheptyl methacrylate, and cyclooctyl methacrylate. Among these, cyclohexyl methacrylate is particularly preferable from the viewpoint of mechanical strength and environmental stability of the amount of charge.
A copolymer containing a monomer other than the alicyclic methacrylate monomer may be used as long as the effect of the present invention is not impaired.

The exposed area ratio of the core material particles on the surface of the carrier particles is preferably in the range of 10.0 to 18.0%. When the exposed area ratio is 10.0% or more, the resistance value of the carrier particles does not become too high, and a high-quality image can be output at the initial stage and after continuous printing. When the exposed area ratio is 18.0% or less, adhesion of carrier particles to the electrostatic latent image carrier (electrophotographic photosensitive member) can be suppressed, and the image quality in continuous printing is not deteriorated, which is preferable.
The exposed portion of the core material particles on the surface of the carrier particles is measured by measuring the coverage of the coating resin on the core material particles by XPS measurement (X-ray photoelectron spectroscopy measurement) by the following method.
K-Alpha manufactured by Thermo Fisher Scientific was used as the XPS measuring device, and Al monochrome X-rays were used as the X-ray source, and the acceleration voltage was set to 7 kV and the emission current was set to 6 mV. , The main element (usually carbon) constituting the coating resin and the main element (usually iron) constituting the core material particles are measured.

The ratio of toner (toner concentration) to the total of carriers and toner is preferably in the range of 4.0 to 8.0% by mass. When the ratio of the toner particles is in the range of 4.0 to 8.0% by mass, the amount of charge of the toner becomes appropriate, and the image quality at the initial stage and after continuous printing becomes better.

The two-component developer according to the present invention can be produced by mixing a carrier and a toner using a mixing device. Examples of the mixing device include a Henschel mixer, a Nauter mixer, and a V-type mixer.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, the indication of "parts" or "%" is used, but unless otherwise specified, it indicates "parts by mass" or "% by mass".

[Example 1]
[Preparation of external additive]
(Preparation of magnesium silicate particles)
(Preparation of magnesium silicate particles 1)
A slurry of Mg (OH) ₂ powder and SiO ₂ powder (average primary particle diameter 0.02 μm) were weighed so that the ratio of MgO: SiO ₂ (molar ratio) was 2: 1 and the MgO concentration was 71.5 g / L, SiO. _A 150 L slurry with a ₂ concentration of 53.3 g / L was prepared, and a 0.6 mmφ zirconia-based bead was used as the media in a sand grinder mill. The media filling rate was 80%, the liquid feeding rate was 4.0 L / min, and the number of slurry passes was 3. Wet pulverization was performed under the conditions of the pass. The slurry was spray-dried with a spray dryer and calcined in an electric furnace at 1100 ° C. for 30 minutes. After that, the fired product was slurried to 300 g / L, and 50 L was slurried with a sand grinder mill using 0.6 mmφ zirconia beads as the media, the media filling rate was 80%, and the liquid feeding speed was 5.6 L / min. Wet pulverization was performed under the condition that the number of slurry passes was 3 passes. The slurry was spray-dried with a spray dryer and pulverized with a sand mill to prepare magnesium silicate particles 1.

When the powder obtained as described above was identified by X-ray diffraction, it was a single phase of forsterite. The average particle size was 0.04 μm.

(Preparation of magnesium silicate particles 2)
Magnesium silicate particles 2 were produced in the same manner as in the production of magnesium silicate particles 1 except that the media was changed from 0.6 mmφ to 0.8 mmφ zirconia-based beads in the production of magnesium silicate particles 1.

(Preparation of magnesium silicate particles 3)
In the preparation of the magnesium silicate particles 1, the magnesium silicate particles 3 were produced in the same manner as in the production of the magnesium silicate particles 1 except that the number of slurry passes was changed from 3 passes to 8 passes.

(Preparation of magnesium silicate particles 4)
In the preparation of magnesium silicate particles 1, the magnesium silicate particles 1 are prepared except that the medium is changed from 0.6 mmφ to 0.4 mmφ zirconia-based beads and the number of slurry passes is changed from 3 passes to 10 passes. Magnesium silicate particles 4 were prepared in the same manner as above.

(Preparation of magnesium silicate particles 5)
Magnesium silicate particles 5 were produced in the same manner as in the production of magnesium silicate particles 1 except that the media was changed from 0.6 mmφ to 0.8 mmφ alumina silica-based beads in the production of magnesium silicate particles 1. ..

(Preparation of alumina particles)
(Preparation of Alumina Particle 1)
As an example of the method for producing alumina according to the present invention, it is adapted to the known burner device described in Example 1 of European Patent No. 0585544 with reference to the contents described in JP2012-224542A. It was made.

320 kg / h of aluminum trichloride (AlCl ₃ ) vapor evaporated in an evaporator at about 200 ° C. is passed through the mixing chamber of the burner by nitrogen. Here, the gas stream is mixed with hydrogen 100 Nm ³ / h and air 450 Nm ³ / h and supplied to the flame via a central tube (diameter 7 mm). As a result, the burner temperature is 230 ° C., and the discharge rate of the tube is about 35.8 m / s. Hydrogen 0.05 Nm ³ / h is supplied as a jacket-type gas via an outer tube. The gas burns in the reaction chamber and cools to about 110 ° C. in the downstream agglomeration zone. There, the primary particles of alumina are agglomerated. From the hydrochloric acid-containing gas generated at the same time, the obtained aluminum oxide particles are separated in a filter or a cyclone, and the powder having moist air is treated at about 500 to 700 ° C. to remove the adhesive chloride. In this way, the alumina particles 1 could be obtained.

(Surface modification)
The alumina particles 1 obtained above were placed in a reaction vessel, and 20 g of the surface modifier isobutyltrimethoxysilane was diluted with 60 g of hexane with respect to 100 g of the alumina powder while stirring the powder with a rotary blade under a nitrogen atmosphere. Alumina particles 1 were obtained by heating and stirring at 200 ° C. for 120 minutes and then cooling with cooling water.

(Preparation of alumina particles 2-4)
The grain size of alumina can be controlled by changing the flame temperature, the content of hydrogen or oxygen, the quality of aluminum trichloride, the residence time in the flame or the length of the cohesive zone. These conditions were appropriately adjusted to obtain alumina particles 2 to 4 having different average particle sizes shown in Table II.
Tables I and II show a list of the average particle sizes of the magnesium silicate particles and the alumina particles prepared above.
The average particle size was measured by the above method using a scanning electron microscope "JSM-7401F" (manufactured by JEOL Ltd.).

[Manufacturing of toner matrix particles]
[Styrene-acrylic (StAc) resin particle dispersion]
(First stage polymerization)
Ion 4 parts by mass of an anionic surfactant made of sodium dodecyl sulfate (C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ SO ₃ Na) in a reaction vessel equipped with a stirrer, temperature sensor, cooling tube and nitrogen introduction device. An aqueous surfactant solution dissolved in 3040 parts by mass of exchanged water was charged. Further, a polymerization initiator solution in which 10 parts by mass of potassium persulfate (KPS) was dissolved in 400 parts by mass of ion-exchanged water was added, and the liquid temperature was raised to 75 ° C.

Next, a polymerizable monomer solution consisting of 532 parts by mass of styrene, 200 parts by mass of n-butylacrylic acid, 68 parts by mass of methacrylic acid and 16.4 parts by mass of n-octyl mercaptan was added dropwise over 1 hour. After the dropping, polymerization (first-stage polymerization) was carried out by heating at 75 ° C. for 2 hours and stirring to prepare a dispersion of styrene-acrylic resin particles.

The weight average molecular weight (Mw) of the styrene-acrylic resin particles in the dispersion was 16500. The weight average molecular weight (Mw) of the resin was determined from the molecular weight distribution measured by gel permeation chromatography (GPC: Gel Permeation Chromatography).

Specifically, the measurement sample was added to tetrahydrofuran (THF) so as to have a concentration of 1 mg / mL, dispersed at room temperature for 5 minutes using an ultrasonic disperser, and then treated with a membrane filter having a pore size of 0.2 μm. Then, a sample solution was prepared. Using a GPC apparatus HLC-8120GPC (manufactured by Tosoh Corporation) and a column TSKguardcolum + TSKgelSuperHZ-m3 series (manufactured by Tosoh Corporation), tetrahydrofuran was flowed as a carrier solvent at a flow rate of 0.2 mL / min while maintaining the column temperature at 40 ° C. 10 μL of the prepared sample solution was injected into the GPC device together with the carrier solvent, the sample was detected using a refractive index detector (RI detector), and a calibration curve measured using monodisperse polystyrene standard particles was used. , The molecular weight distribution of the sample was calculated. The calibration curves have molecular weights of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , 3.9 × 10, respectively. ^{5, 8.6 × 10 5, 2} × 10 6, by measuring the polystyrene standard particle of 10 is 4.48 × 10 ⁶ (Pressure Chemical Co.) was prepared.

(Second stage polymerization)
A polymerizable single amount consisting of 101.1 parts by mass of styrene, 62.2 parts by mass of n-butylacrylic acid, 12.3 parts by mass of methacrylic acid and 1.75 parts by mass of n-octyl mercaptan in a flask equipped with a stirrer. The body solution was charged. Further, 93.8 parts by mass of paraffin wax HNP-57 (manufactured by Nippon Wax Co., Ltd.) was added as a mold release agent, and the internal temperature was heated to 90 ° C. to dissolve it to prepare a monomer solution.

In another container, an aqueous surfactant solution prepared by dissolving 3 parts by mass of the anionic surfactant used in the first-stage polymerization in 1560 parts by mass of ion-exchanged water was charged and heated to an internal temperature of 98 ° C. To this aqueous surfactant solution, 32.8 parts by mass (in terms of solid content) of the dispersion of styrene-acrylic resin particles obtained by the first-stage polymerization was added, and a monomer solution containing paraffin wax was further added. .. A dispersion of emulsified particles (oil droplets) having a particle diameter of 340 nm was prepared by mixing and dispersing over 8 hours using a mechanical disperser Clairemix (manufactured by M-Technique) having a circulation path.

A polymerization initiator solution in which 6 parts by mass of potassium persulfate was dissolved in 200 parts by mass of ion-exchanged water was added to this dispersion. Polymerization (second stage polymerization) was carried out by heating and stirring this system at 98 ° C. for 12 hours to prepare a dispersion of styrene-acrylic resin particles.
The weight average molecular weight (Mw) of the styrene-acrylic resin particles in the dispersion was 23000.

(Third stage polymerization)
A polymerization initiator solution in which 5.45 parts by mass of potassium persulfate was dissolved in 220 parts by mass of ion-exchanged water was added to the dispersion of styrene-acrylic resin particles obtained in the second stage polymerization. To this dispersion, 1 part by mass of a polymerizable monomer solution consisting of 293.8 parts by mass of styrene, 154.1 parts by mass of n-butylacrylic acid and 7.08 parts by mass of n-octyl mercaptan under a temperature condition of 80 ° C. Dropped over time. After completion of the dropping, polymerization (third-stage polymerization) was carried out by heating and stirring for 2 hours, and then the mixture was cooled to 28 ° C. to obtain a dispersion of styrene-acrylic resin particles. The weight average molecular weight (Mw) of the styrene-acrylic resin particles in the dispersion was 26,800.

[Crystalline polyester particle dispersion]
In a heat-dried three-port flask, 355.8 parts by mass of dodecanedioic acid as a polyvalent carboxylic acid monomer, 254.3 parts by mass of 1,9-nonanediol as a polyhydric alcohol monomer, and tin octylate 3 as a catalyst. .21 parts by mass was added. After removing the air from the container by a depressurization operation, the container was replaced with nitrogen gas to create an inert atmosphere, and reflux treatment was performed at 180 ° C. for 5 hours by mechanical stirring. The temperature was gradually raised in an inert atmosphere, and the mixture was stirred at 200 ° C. for 3 hours to obtain a viscous liquid product. While further air-cooling, the molecular weight of this product was measured by GPC, and when the weight average molecular weight (Mw) reached 15,000, the reduced pressure was released to stop the polycondensation reaction to obtain a crystalline polyester resin. The obtained crystalline polyester resin had a melting point of 69 ° C.

Methyl ethyl ketone and isopropyl alcohol were added to a reaction vessel equipped with an anchor blade that provided stirring power. Further, the crystalline polyester resin roughly pulverized with a hammer mill was gradually added and stirred, and completely dissolved to obtain a polyester resin solution to be an oil phase. A small amount of a dilute aqueous ammonia solution was added dropwise to the stirred oil phase, and then the oil phase was added dropwise to ion-exchanged water for phase inversion emulsification, and then the solvent was removed while reducing the pressure with an evaporator. Crystalline polyester resin particles are dispersed in the reaction system, and ion-exchanged water is added to the dispersion to adjust the solid content to 20% by mass to prepare a dispersion of crystalline polyester resin particles.
The volume-based median diameter of the crystalline polyester resin particles in the dispersion was measured using a particle size distribution measuring device "Nanotrack Wave (manufactured by Microtrack Bell)" and found to be 173 nm.

[Amorphous polyester particle dispersion]
In a reaction vessel equipped with a stirrer, a nitrogen introduction tube, a temperature sensor and a rectification tower, 139.5 parts by mass of terephthalic acid and 15.5 parts by mass of isophthalic acid were added as polyhydric carboxylic acid monomers to a monohydric alcohol. As a metric, 2 mol of 2,2-bis (4-hydroxyphenyl) propanepropylene oxide (molecular weight = 460) 290.4 parts by mass and 2 mol of 2,2-bis (4-hydroxyphenyl) propaneethylene oxide were added. A product (molecular weight 404) of 60.2 parts by mass was charged. The temperature of the reaction system was raised to 190 ° C. over 1 hour, and after confirming that the inside of the reaction system was uniformly stirred, 3.21 parts by mass of tin octylate was added as a catalyst. While distilling off the generated water, the temperature of the reaction system was raised from the same temperature to 240 ° C. over 6 hours, and the dehydration condensation reaction was continuously carried out for 6 hours while maintaining the temperature at 240 ° C. to carry out an amorphous polyester. Obtained resin. The obtained amorphous polyester resin had a peak molecular weight (Mp) of 12,000 and a weight average molecular weight (Mw) of 15,000.

A dispersion of amorphous polyester resin particles having a solid content of 20% by mass was prepared by performing the same operation as the preparation of the dispersion of crystalline polyester resin particles with respect to the obtained amorphous polyester resin. ..
The volume-based median diameter of the amorphous polyester resin particles in the dispersion was measured using a particle size distribution measuring device "Nanotrack Wave (manufactured by Microtrack Bell)" and found to be 216 nm.

[Colorant particle dispersion]
90 parts by mass of sodium dodecyl sulfate was stirred and dissolved in 1600 parts by mass of ion-exchanged water. While stirring this solution, 420 parts by mass of Carbon Black Regal 330R (manufactured by Cabot Corporation) was gradually added. Next, a dispersion of colorant particles was prepared by performing dispersion treatment using a stirrer Clairemix (manufactured by M-Technique).

The particle size of the colorant particles in the dispersion was measured using a particle size distribution measuring device "Nanotrack Wave (manufactured by Microtrack Bell)" and found to be 117 nm. The method for producing the toner matrix particles is as follows. including.

[Manufacturing method of toner matrix particles 1]
270 parts by mass (solid content equivalent) of styrene-acrylic resin particle dispersion as the first-stage injection dispersion in a 5-liter stainless steel reactor equipped with a stirrer, cooling tube and temperature sensor, amorphous polyester resin particles 270 parts by mass (solid content equivalent) of the dispersion liquid, 60 parts by mass (solid content conversion) of the crystalline polyester resin particle dispersion liquid, and 48 parts by mass (solid content conversion) of the colorant particle dispersion liquid were added. Further, 380 parts by mass of ion-exchanged water was added, and the pH was adjusted to 10 with 5 (mol / liter) sodium hydroxide aqueous solution while stirring.

Under stirring, 5.0 parts by mass of a 10 mass% polyaluminum chloride aqueous solution was added dropwise over 10 minutes to raise the internal temperature to 75 ° C. The particle size was measured using Multisizer 3 (manufactured by Beckman Coulter, aperture diameter; 50 μm), and when the average particle size reached 5.8 μm, 160 parts by mass of sodium chloride was converted to 640 parts by mass of ion-exchanged water. A dissolved aqueous solution of sodium chloride was added. After continuing heating and stirring, the flow-type particle image measuring device FPIA-2100 (manufactured by Sysmex Corporation) was used to cool the internal temperature to 25 ° C. at a rate of 20 ° C./min when the average circularity reached 0.960.

After cooling, solid-liquid separation was performed using a basket-type centrifuge. The resulting wet cake was washed in the same basket-type centrifuge with ion-exchanged water at 35 ° C. until the electrical conductivity of the filtrate reached 5 μS / cm. Then, it was transferred to a flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.) and dried until the water content became 0.5% by mass.

(External agent treatment process)
For the "toner matrix particle 1" produced as described above,
・ Magnesium silicate 1 0.5% by mass
・ Alumina particles 1 0.5% by mass
Toner shell mixer model "FM20C / I" (manufactured by Nippon Coke Industries Co., Ltd.), and set the rotation speed so that the blade tip peripheral speed is 40 m / s for 20 minutes. The mixture was stirred to prepare "toner 1" composed of toner particles 1.

At this time, the temperature at the time of mixing the external additive is set to 40 ° C. ± 1 ° C., and when the temperature reaches 41 ° C., the cooling water is poured into the outer bath of the Henschel mixer at a flow rate of 5 L / min. When the temperature reached 39 ° C., the temperature inside the Henschel mixer was controlled by flowing cooling water so as to be 1 L / min.

[Preparation of toners 2 to 12]
In the production of the toner 1, the toner 12 was produced from the toner 2 by changing the types of the carrier and the external additive as shown in Table III.
In the production of the toner 11, silica particles (NAX50 average particle size 28 nm manufactured by Nippon Aerosil Co., Ltd.) were used instead of the alumina particles.
Further, in the production of the toner 12, titania particles (STT100H average particle size 20 nm manufactured by Titan Kogyo Co., Ltd.) were used instead of the alumina particles.

[Creation of carrier]
(Preparation of carrier core material particles 1)
The raw materials are weighed so that MnO: 35 mol%, MgO: 14.5 mol%, Fe ₂ O ₃ : 50 mol% and SrO: 0.5 mol%, mixed with water, and then pulverized in a wet media mill for 5 hours. To obtain a slurry.

The obtained slurry was dried with a spray dryer to obtain spherical particles. After adjusting the particle size of the particles, the particles were heated at 950 ° C. for 2 hours and calcined. After pulverizing with a wet ball mill for 1 hour using stainless beads having a diameter of 0.3 cm, the zirconia beads having a diameter of 0.5 cm were further pulverized for 4 hours. 0.8% by mass of PVA was added as a binder with respect to the solid content, then granulated and dried by a spray dryer, and kept at a temperature of 1350 ° C. for 5 hours in an electric furnace for main firing.
Then, it was crushed, further classified to adjust the particle size, and then the low magnetic force product was separated by magnetic beneficiation to obtain carrier core material particles 1. The particle size of the carrier core material particles 1 was 35 μm.

(Preparation of resin 1 for coating core material)
Cyclohexyl methacrylate and methyl methacrylate were added to an aqueous solution of 0.3% by mass of sodium benzenesulfonate at a “mass ratio = 50:50” (copolymerization ratio), and 0.5% by mass of the total amount of monomers. The "coating material 1" was prepared by adding a corresponding amount of potassium persulfate, performing emulsion polymerization, and drying by spray drying. The weight average molecular weight of the obtained covering material 1 was 500,000.

(Preparation of resin 2 for coating core material)
In the preparation of the core material coating resin 1, the coating material 2 was prepared only with methyl methacrylate.
(Preparation of carrier 1)
100 parts by mass of "carrier core material particles 1" and 4.5 parts by mass of "coating material 1" prepared above as core material particles were put into a high-speed stirring mixer with horizontal stirring blades, and the peripheral speed of the horizontal rotary blade was After mixing and stirring at 22 ° C. for 15 minutes under the condition of 8 m / sec, the surface of the core material particles is coated with a coating material by the action of mechanical impact force (mechanochemical method). Then, "Carrier 1" was manufactured.

(Preparation of carrier 2)
In the production of the carrier 1, the carrier 2 was produced by using the covering material 2 instead of the covering material 1.

[Preparation of developer]
For the toners 1 to 12 and the carriers 1 and 2 produced as described above, the compounding ratio was set to 6 parts by mass of the toner with respect to 100 parts by mass of the carrier, and the room temperature and humidity (temperature 10 ° C., relative humidity 20% RH, temperature 30) This was performed by mixing toner and carriers using a V-blender in an environment of ° C. and relative humidity of 80% RH). The treatment was performed with the rotation speed of the V blender set to 20 rpm and the stirring time set to 20 minutes, and the mixture was further sieved with a mesh having an opening of 125 μm to prepare developers 1 to 13 with the combination of toner and carrier shown in Table III. did.

<< Evaluation >>
[Evaluation of toner fluidity]
As an index of toner fluidity, the bulk density was determined by a Kawakita type bulk density measuring machine (IH2000 type). The specific method for measuring the bulk density is as follows.

After leaving the toner to be measured overnight in an environment of normal temperature and humidity (20 ° C., 50 RH%), place 20 g of the sample on a 48-mesh sieve and drop it at a vibration intensity of 6 for 30 seconds, then stop the vibration for 3 minutes. After standing still, the scraped bulk density (toner mass / volume (20 cm ³ )) was determined. The above values were judged based on the following evaluation criteria. The results are shown in Table III below. Here, those with evaluations of ○ to △ were regarded as pass levels.

◯: The ground bulk density is 40 g / 100 ml or more (excellent toner fluidity).
Δ: The ground bulk density is 35 g / 100 ml or more and less than 40 g / 100 ml (toner fluidity is practical).
X: The ground bulk density is less than 35 g / 100 ml (poor toner fluidity).

[Evaluation of scatterability]
Using the image forming apparatus "bizhub PRESS C1070" (manufactured by Konica Minolta), the developing agents 1 to 13 are sequentially loaded into the cyan developing apparatus, and in an environment of normal temperature and humidity (temperature 20 ° C., relative humidity 50% RH). Evaluation was performed.

Woodfree paper having a print ratio of 5% character images cyan A4 (64g / ^{m 2)} to 200,000 prints, then fine paper of the character image with a printing ratio of 45% A4 (64g / ^{m 2)} to 200,000 prints After printing, the state of stains inside the machine due to toner scattering around the developer was visually observed and evaluated as follows.
The evaluation of toner scattering was evaluated according to the following evaluation criteria, and in the present invention, ⊚, ◯ or Δ was regarded as acceptable.

⊚: No toner scattering is observed, and even if the user replaces the developing unit, the hands are not soiled at all. ○: Scattered toner is observed on the upper lid near the developing roller. △: Part of the upper lid of the developing unit Scattered toner is seen. ×: Toner is scattered enough to require hand washing after the user replaces the developing unit.

[Evaluation of developer fluidity]
Using the image forming apparatus, 200,000 sheets of a character image having a cyan printing rate of 5% were printed on A4 woodfree paper (64 g / m ² ), the developer was extracted, and 20 g of the developer was placed in an 8 mL screw vial. Then, the developer was freely dropped from the screw vial from a height of 15 cm, and the rank evaluation of the developer fluidity was performed according to the evaluation criteria shown below.

(Evaluation criteria)
◎: Flows down from the container in a constant amount ○: Flows down from the container indefinitely △: Flows down when the container is tapped ×: Flows down when the container is tapped strongly

[Evaluation of photoconductor scratches]
Using the image forming apparatus, 200,000 sheets of a character image having a cyan print rate of 5% are printed on A4 high-quality paper (64 g / m ² ), and then a character image having a print rate of 45% is printed on A4 high-quality paper (64 g / m ² ). After printing 200,000 sheets in ² ), a halftone image was output and the presence or absence of streaks on the image due to surface scratches on the photoconductor was evaluated. The evaluated photoconductor is a photoconductor installed at the cyan position.

(Evaluation criteria)
⊚: No problem with halftone image after printing 100,000 sheets (good)
◯: No streaks are visible in the halftone image after printing 100,000 sheets, but the image has a grainy appearance (no problem in practical use).
×: After printing 100,000 sheets, streaks due to surface scratches can be confirmed on the halftone image (there is a problem in practical use).

[Abrasion resistance evaluation]
Using the image forming apparatus, 200,000 sheets of a character image having a cyan print rate of 5% are printed on A4 woodfree paper (64 g / m ² ), and then a character image having a print rate of 45% is printed on A4 woodfree paper (64 g / m ² ). After printing 200,000 sheets in ² ), the thickness of the surface layer of the photoconductor was measured, the amount of wear of the surface layer was calculated, and the evaluation was performed according to the following evaluation criteria. The thickness was measured using an eddy current type film thickness measuring machine "Fisherscope MMS PC" (manufactured by Fisher Instruments).

(Evaluation criteria)
⊚: When the amount of wear is within 0.3 μm (pass)
◯: When the amount of wear is greater than 0.3 μm and within 0.6 μm (pass)
Δ: When the amount of wear is greater than 0.6 μm and within 1.0 μm (pass)
X: When the amount of wear is larger than 1.0 μm (failure)

From Table III, it can be seen that the developer using the toner of the present invention is excellent in scattering property.

Claims (4)

A toner for electrostatic latent image development having an external additive on the surface of the toner matrix particles, wherein the external agent contains magnesium silicate particles and alumina particles, and the average particle size of the magnesium silicate particles is 20 to 100 nm. Toner for electrostatic latent image development, which is characterized by being within the range of. The toner for electrostatic latent image development according to claim 1, wherein the average particle size of the magnesium silicate particles is larger than the average particle size of the alumina particles. The toner for electrostatic latent image development according to claim 1 or 2, wherein the average particle size of the alumina particles is in the range of 10 to 50 nm. A two-component development characterized by containing the toner for electrostatic latent image development according to any one of claims 1 to 3 and a carrier having a resin coating of an alicyclic methacrylate monomer polymer. Agent.