JP6291706B2 - Toner for developing electrostatic image, two-component developer and image forming method - Google Patents

Description

  The present invention relates to an electrostatic charge image developing toner (hereinafter also simply referred to as “toner”) and a two-component developer used for electrophotographic image formation, and an image forming method using the two-component developer. .

In an electrophotographic image forming method, a toner image is formed using a two-component developer composed of toner and carrier, and the toner image is fixed on an image support to form an image. Various external additives are added to the toner constituting the two-component developer for the purpose of imparting fluidity to the toner and improving chargeability, developability, transferability, and cleaning properties.
In recent years, two-component developers have been required to have higher reliability, specifically, improved charged state stability, developability, transferability, and cleaning properties, as well as high durability. There is also a need to make it.

As a method for improving the stability of the charged state of the toner with respect to any environment, a method of adding an external additive whose surface has been subjected to a hydrophobic treatment to the toner particles is known. In particular, it is known that an external additive hydrophobized with a linear alkylsilane has a great effect.
In addition, a method using large particles as an external additive is known in order to ensure long-term cleaning performance. When the large-diameter particles are caught between the blade and the photoreceptor substrate, the toner particles can be prevented from slipping through and the cleaning performance can be improved. Further, since the adhesion force between the toner particles to which the external additive consisting of large-diameter particles is added and the carrier particles and the substrate (photosensitive substrate or intermediate transfer belt substrate) is reduced, the developability and transferability are improved. be able to.

On the other hand, as a technique for improving the durability of a two-component developer, Patent Document 1 discloses a method of hardening a surface layer of toner particles. According to this method, a burying prevention shell layer is formed on the surface of the core particles, whereby the burying of the external additive in the toner particles can be suppressed and high durability can be obtained. However, when the collision between the toner particles and the carrier particles or the collision between the toner particles is performed for a long time, the burying of the external additive gradually proceeds, eventually resulting in a decrease in chargeability, specifically a decrease in saturation value. In addition, there is a problem that the charge rising property is deteriorated, and further, the fluidity, developability, transfer property and cleaning property are deteriorated.
In addition, a method of suppressing the burying of small-diameter particles by using small-diameter particles together with large-diameter particles is known as an external additive (see Patent Document 2). However, although this method can suppress the embedding of the small-diameter component, the large-diameter particle gradually collides with the carrier particle and the toner particle. There is a problem that the cleaning performance and the like are lowered.

JP 2006-285215 A JP 2007-304494 A

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a toner for developing an electrostatic image, a two-component developer, and a high durability while achieving high reliability. An object is to provide an image forming method.

The toner for developing an electrostatic charge image of the present invention includes a toner particle in which a plurality of bumps made of a styrene-acrylic modified polyester resin are formed on the surface of a base particle containing a binder resin made of a styrene-acrylic copolymer, and an outer toner particle. Having an additive ,
The average height of the bump is 50 to 120 nm,
The average diameter of the bump is 100 to 500 nm,
The average distribution density of the bumps in the base particles surface 2 to 15 / [mu] m are ^two der,
The external additive includes hydrophobized silica fine particles having an average particle diameter of 20 to 40 nm in which a reaction product derived from an alkylsilane having 6 to 16 carbon atoms is present on the surface .

  In the toner for developing an electrostatic charge image of the present invention, it is preferable that an external additive comprising large-diameter silica fine particles having a particle diameter of 60 to 120 nm is further added to the toner particles.

  In the toner for developing an electrostatic charge image of the present invention, an external additive composed of small-sized silica fine particles having a particle diameter of 5 to 20 nm or small-sized titania fine particles having a particle diameter of 5 to 20 nm is further added to the toner particles. It is preferable to be made.

The two-component developer of the present invention comprises the above-mentioned toner for developing an electrostatic image and a carrier having an apparent density of 1.0 to 2.0 g / cm ³ .

  The image forming method of the present invention is characterized by using the above two-component developer.

In the toner for developing an electrostatic charge image of the present invention, a plurality of bumps are formed on the surface of the base particles constituting the toner particles, so that the bumps are caught between the blade and the photoreceptor substrate, and the toner particles slip through. Therefore, the cleaning property is ensured even during printing.
In the toner of the present invention, when an external additive is added, a plurality of bumps having a height approximately equal to the particle size of the external additive are formed, so that the external additive is a base material. By entering between the bumps formed on the particle surface, the external additive is prevented from receiving an impact force directly due to the collision between the toner particles and the carrier particles or the collision between the toner particles. Since transfer of the additive to the carrier and embedding in the toner particles are suppressed, developability and transferability are ensured even during printing durability. In the present invention, even if no external additive is added, the adhesion between the toner particles or between the carrier particles and the toner particles is reduced and the fluidity is improved. It is also expected as a toner constituting the toner.
Furthermore, in the toner of the present invention, silica fine particles having a specific particle size (hereinafter, also referred to as “specific hydrophobic silica fine particles”) hydrophobized with a long-chain alkylsilane are added as external additives. The difference in charging environment is reduced, and specific hydrophobized silica fine particles enter between the bumps formed on the surface of the base particle, thereby causing collision between toner particles and carrier particles or between toner particles. Since the specific hydrophobized silica fine particles are prevented from receiving impact force directly, the embedding of the specific hydrophobized silica fine particles in the toner particles is suppressed, and the difference in charging environment is extremely large even during printing durability. It is kept small. As described above, according to the toner of the present invention, high durability can be obtained while sufficient reliability such as stability of charge state, developability, transferability, and cleaning property is ensured.

  According to the two-component developer of the present invention, it is possible to achieve high durability while achieving high reliability by including the electrostatic image developing toner and a carrier having an apparent density in a specific range. .

  According to the image forming method of the present invention, a high-quality image can be formed over a long period of time by using the two-component developer.

3 is an SEM image showing an example of toner particles according to the present invention. It is a SEM image which shows another example of the toner particle which concerns on this invention, and represents the height of the bump by h and the diameter by d.

  Hereinafter, the present invention will be described in detail.

〔toner〕
The toner of the present invention is formed so as to protrude from the surface of a base particle containing a binder resin (hereinafter also referred to as “matrix resin”) made of a styrene-acrylic copolymer. And toner particles comprising a plurality of bumps made of styrene-acryl-modified polyester resin. Here, the bump is a protrusion formed on the surface of the base particle and has a shape shown in FIGS. 1 and 2.
The toner of the present invention may be composed only of toner particles or may have a configuration to which an external additive is added, but usually a configuration to which an external additive is added is preferred.

〔bump〕
In the toner of the present invention, a plurality of bumps protruding from the surface are formed on the surface of the base particles constituting the toner particles. As shown in FIGS. 1 and 2, the bump is a dome-shaped protrusion. By forming a plurality of such bumps on the toner of the present invention, the bumps are caught between the blade and the photoreceptor substrate, and the toner particles are prevented from slipping through, so that the cleaning property is ensured even during printing durability. Is done. In the toner of the present invention, when an external additive is added, a plurality of bumps having a height approximately equal to the particle size of the external additive are formed, so that the external additive is a base material. By entering between the bumps formed on the particle surface, the external additive is prevented from receiving an impact force directly due to the collision between the toner particles and the carrier particles or the collision between the toner particles. Since transfer of the additive to the carrier and embedding in the toner particles are suppressed, developability and transferability are ensured even during printing durability.

The average height of the bump from the surface of the base particle is 50 to 120 nm, more preferably 70 to 100 nm.
When the average height of the bump is less than 50 nm, when an external additive having a particle size of 50 nm or more is added, the external additive is caused by collision between toner particles and carrier particles or between toner particles. Since the agent is buried in the toner particles, high durability cannot be realized. On the other hand, when the average height of the bumps exceeds 120 nm, an external additive exists between the bumps, and good flowability due to the external additive cannot be obtained, so that the charge rising property is hindered.
Here, the bump height refers to a protruding height h from the surface of the base particle as shown in FIG.

The average diameter of the bump is 100 to 500 nm, more preferably 250 to 350 nm.
When the average diameter of the bump is less than 100 nm, the external additive is buried in the toner particles due to the collision between the toner particles and the carrier particles or the collision between the toner particles, so that high durability can be realized. Can not. On the other hand, when the average diameter of the bump exceeds 500 nm, when an external additive described later is added, the external additive adheres on the bump, and high durability cannot be realized.
Here, the diameter of the bump means a maximum diameter d (hereinafter, also referred to as “maximum width in the projection image”) represented in the projection image, as shown in FIG. 2.

The average distribution density of the bumps on the surface of the base particle is 2 to 15 / μm ² , and more preferably 4 to 8 / μm ² .
When the average distribution density of the bumps is less than ² particles / μm ² , the external additive is buried in the toner particles due to the collision between the toner particles and the carrier particles or the collision between the toner particles. It cannot be realized. On the other hand, when the average distribution density of the bumps exceeds 15 pieces / μm ² , when an external additive described later is added, the external additive adheres onto the bump and high durability can be realized. Can not.

  In the present invention, when the external additive described later is added by satisfying the ranges of the average height, the average diameter, and the average distribution density, the bump has a height larger than the particle diameter of the external additive. Since the bumps having the surface are present on the base particle surface at an appropriate occupancy ratio, it is suppressed that the external additive receives an impact force directly due to the collision between the toner particles and the carrier particles or the collision between the toner particles. Embedding of the external additive in the toner particles is suppressed, and as a result, high durability is realized.

In the present invention, the average height, average diameter, and average distribution density of the bumps are measured as follows.
Using a scanning electron microscope “JSM-7401F” (manufactured by JEOL), observed 10,000 times, image processing was performed from SEM image data, the number of bumps per square micrometer, diameter and height per toner particle Measure the thickness. The same measurement is performed for 10 particles, and the average value is calculated.
As for the number of bumps, those existing on the boundary line are not counted.

  The bump is made of a resin containing a styrene-acrylic modified polyester resin (hereinafter also referred to as “bump resin”).

  The resin for bumps preferably has a glass transition point of 50 to 65 ° C., more preferably 55 to 60 ° C., and a softening point of 95 to 110 ° C. from the viewpoints of heat-resistant storage properties and low-temperature fixability. Preferably there is.

The glass transition point of the resin for bumps is measured by a method (DSC method) defined in ASTM (American Society for Testing and Materials) D3418-82.
Further, the softening point of the resin for bumps is measured as follows.
In an environment of 20 ° C. ± 1 ° C. and 50% ± 5% RH, 1.1 g of a measurement sample (bump resin) is placed in a petri dish and flattened and allowed to stand for 12 hours or more, and then a molding machine “SSP-10A” (Shimadzu Corporation) pressurizes with a force of 3820 kg / cm ² for 30 seconds to make a cylindrical molded sample with a diameter of 1 cm, and then this molded sample is 24 ° C. ± 5 ° C., 50% ± 20% RH Under the environment, the hole of the cylindrical die was measured with a flow tester “CFT-500D” (manufactured by Shimadzu Corporation) under the conditions of a load of 196 N (20 kgf), a starting temperature of 60 ° C., a preheating time of 300 seconds, and a heating rate of 6 ° C./min. (1 mm diameter × 1 mm) from the end of preheating using a piston with a diameter of 1 cm, offset method temperature T _offset measured at a setting of an offset value of 5 mm by the temperature rise method melting temperature measurement method, The softening point of the resin for bumps.

The content ratio of the bump resin to the matrix resin constituting the matrix particles is preferably 10 to 30% by mass, and more preferably 15 to 25% by mass.
If the content of the bump resin in the base resin is too low, sufficient heat-resistant storage stability cannot be secured, and if the content of the bump resin in the base resin is excessive, the fixing property is inhibited. To do.

[Styrene-acrylic modified polyester resin]
In the present invention, the styrene-acrylic modified polyester resin constituting the resin for bumps is one in which a styrene-acrylic polymer segment is bonded to the end of the polyester segment. Moreover, the styrene-acrylic polymer segment may be bonded to the side chain of the polyester segment.

The content of the styrene-acrylic polymer segment in the styrene-acrylic modified polyester resin (hereinafter also referred to as “styrene-acrylic modification rate”) is preferably 10 to 30% by mass, more preferably 15 to 25% by mass. %.
Specifically, the styrene-acrylic modification rate is the total mass of the resin material used for synthesizing the styrene-acrylic modified polyester resin, that is, an unmodified polyester resin that becomes a polyester segment, and a styrene-acrylic polymer. The aromatic vinyl monomer and (meta) with respect to the total mass of the aromatic vinyl monomer and (meth) acrylic acid ester monomer to be combined with the both reactive monomers for bonding them. ) Ratio of mass of acrylic acid ester monomer.
When the styrene-acryl modification rate in the styrene-acryl-modified polyester resin is in the above range, both heat resistance and fixability can be achieved.

The weight average molecular weight (Mw) of the styrene-acryl-modified polyester resin is preferably 1,500 to 60,000, more preferably 3,000 to 40,000.
When the weight average molecular weight is 1,500 or more, a cohesive force suitable as a resin can be obtained, and the hot offset property is good, which is preferable. Further, it is preferable that the weight average molecular weight is 60,000 or less because good hot offset property and a suitable minimum fixing temperature can be obtained.

  In the present invention, the weight average molecular weight of the styrene-acrylic modified polyester resin is measured by a general GPC method.

[Production Method of Styrene-Acrylic Modified Polyester Resin]
An existing general scheme can be used as a method for producing the styrene-acrylic modified polyester resin constituting the bump resin as described above. The following three methods are listed as typical methods.
(A-1) A polyester segment is polymerized in advance, and both reactive monomers are reacted with the polyester segment, and an aromatic vinyl monomer and (meta) are formed to form a styrene-acrylic polymer segment. ) A method of forming a styrene-acrylic polymer segment by reacting an acrylate monomer.
(A-2) A polyvalent carboxylic acid monomer for polymerizing a styrene-acrylic polymer segment in advance, reacting the styrene-acrylic polymer segment with both reactive monomers, and further forming a polyester segment And a method of forming a polyester segment by reacting a polyhydric alcohol monomer.
(B) A method in which a polyester segment and a styrene-acrylic polymer segment are respectively polymerized in advance, and both are reacted with each other by reacting them with each other.
In this specification, the both reactive monomers are a group capable of reacting with a polyvalent carboxylic acid monomer and / or a polyhydric alcohol monomer for forming a polyester segment of a styrene-acryl-modified polyester resin, and a polymerizable unsaturated group. And a monomer having

The method (A-1) will be specifically described.
(1) a mixing step of mixing an unmodified polyester resin, an aromatic vinyl monomer and a (meth) acrylic acid ester monomer, and both reactive monomers; and
(2) A styrene-acrylic polymer segment can be formed at the end of the polyester segment by passing through a polymerization step of polymerizing the aromatic vinyl monomer and the (meth) acrylic acid ester monomer.

  In the mixing step (1), it is preferable to heat. The heating temperature may be within a range where unmodified polyester resin, aromatic vinyl monomer, (meth) acrylic acid ester monomer and both reactive monomers can be mixed. Since it is obtained and polymerization control becomes easy, it can be set to, for example, 80 to 120 ° C., more preferably 85 to 115 ° C., and further preferably 90 to 110 ° C.

Among unmodified polyester resin, aromatic vinyl monomer, (meth) acrylic acid ester monomer and both reactive monomers, aromatic vinyl monomer and (meth) acrylic acid ester monomer The total proportion of the resin material used, that is, the total amount of the aromatic vinyl monomer and the (meth) acrylic acid ester monomer when the total mass of the four members is 100% by mass. The ratio is preferably 5% by mass or more and 30% by mass or less, and particularly preferably 5% by mass or more and 20% by mass or less.
The total ratio of the aromatic vinyl monomer and the (meth) acrylic acid ester monomer to the total mass of the resin material used is within the above range, so that the bump height, the maximum width in the projected image, and the distribution Can be controlled. On the other hand, when the ratio is too small, the bumps are not fused to the base particles, that is, the bumps may not be formed. Moreover, when the said ratio is excessive, there exists a possibility that a bump may be buried in the base particle.

The relative proportion of the aromatic vinyl monomer and the (meth) acrylic acid ester monomer is such that the glass transition point (Tg) calculated by the FOX formula represented by the following formula (A) is 35. It is preferable that the ratio is in the range of -80 ° C, preferably 40-60 ° C.
Formula (A): 1 / Tg = Σ (Wx / Tgx)
[In Formula (A), Wx is the weight fraction of monomer x, and Tgx is the glass transition point of the homopolymer of monomer x. ]
In the present specification, both reactive monomers are not used for calculation of the glass transition point.

  Among unmodified polyester resin, aromatic vinyl monomer, (meth) acrylic acid ester monomer, and both reactive monomers, the proportion of both reactive monomers used is the total mass of the resin material used, that is, It is preferable that the ratio of the both reactive monomers is 0.1% by mass or more and 5.0% by mass or less, especially 0.5% by mass or more and 3. It is preferable that it is 0 mass% or less.

[Aromatic vinyl monomers and (meth) acrylic acid ester monomers]
The aromatic vinyl monomer and the (meth) acrylic acid ester monomer for forming the styrene-acrylic polymer segment have an ethylenically unsaturated bond capable of performing radical polymerization.
Examples of the aromatic vinyl monomer include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples include 4-dimethylstyrene, 3,4-dichlorostyrene, and derivatives thereof.
These aromatic vinyl monomers can be used alone or in combination of two or more.
Examples of (meth) acrylic acid ester monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, and methacrylic acid. Examples include butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.
These (meth) acrylic acid ester monomers can be used alone or in combination of two or more.

  As an aromatic vinyl monomer and (meth) acrylic acid ester monomer for forming a styrene-acrylic polymer segment, styrene or a derivative thereof is used from the viewpoint of obtaining excellent chargeability and image quality characteristics. It is preferable to use a large amount. Specifically, the amount of styrene or a derivative thereof used is the total amount of monomers (aromatic vinyl monomer and (meth) acrylic ester single monomer used to form a styrene-acrylic polymer segment). It is preferable that it is 50 mass% or more in the body.

[Amotropic monomer]
As the both reactive monomers for forming a styrene-acrylic polymer segment, a group capable of reacting with a polyvalent carboxylic acid monomer and / or a polyhydric alcohol monomer for forming a polyester segment, a polymerizable unsaturated group, Specifically, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, maleic anhydride, and the like can be used.

[Polyester resin]
The polyester resin used for preparing the styrene-acrylic modified polyester resin is produced by polycondensation reaction in the presence of an appropriate catalyst using polyvalent carboxylic acid monomer (derivative) and polyhydric alcohol monomer (derivative) as raw materials. It is.

  As polyvalent carboxylic acid monomer derivatives, alkyl esters, acid anhydrides and acid chlorides of polyvalent carboxylic acid monomers can be used. As polyhydric alcohol monomer derivatives, ester compounds of polyhydric alcohol monomers and hydroxycarboxylic acids are used. Can be used.

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

  As the polyvalent carboxylic acid monomer, an aliphatic unsaturated dicarboxylic acid such as fumaric acid, maleic acid or mesaconic acid is preferably used.

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

  The ratio of the polyhydric carboxylic acid monomer to the polyhydric alcohol monomer is preferably an equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] of the polyhydric alcohol monomer and the carboxyl group [COOH] of the polyhydric carboxylic acid. Is 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2.

  As the catalyst for synthesizing the polyester resin, various conventionally known catalysts can be used.

  The unmodified polyester resin has a partially branched structure or a crosslinked structure formed by selecting a carboxylic acid valence or an alcohol valence as a polyvalent carboxylic acid monomer and / or a polyhydric alcohol monomer to be used. May be.

(Polymerization initiator)
In the polymerization step (2), it is preferable to carry out the polymerization in the presence of a radical polymerization initiator, and the timing of addition of the radical polymerization initiator is not particularly limited, but mixing is performed because radical polymerization can be easily controlled. It is preferable to add after the step (1).

  Various known polymerization initiators are preferably used as the polymerization initiator. Specifically, for example, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, Lauroyl oxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid-tert-hydroperoxide, performic acid-tert -Butyl, peracetic acid-tert-butyl, perbenzoic acid-tert-butyl, perphenylacetic acid-tert-butyl, permethoxyacetic acid-tert-butyl, per-N- (3-toluyl) palmitic acid-tert-butyl, etc. Peroxides; 2 2'-azobis (2-aminodipropane) hydrochloride, 2,2'-azobis- (2-aminodipropane) nitrate, 1,1'-azobis (1-methylbutyronitrile-3-sulfonic acid sodium salt) 4, 4'-azobis-4-cyanovaleric acid, poly (tetraethylene glycol-2,2'-azobisisobutyrate) and other azo compounds.

[Chain transfer agent]
In the polymerization step (2), a generally used chain transfer agent can be used for the purpose of adjusting the molecular weight of the styrene-acrylic polymer segment. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptans and mercapto fatty acid esters.
The chain transfer agent is preferably mixed with the resin material in the mixing step (1).

  The addition amount of the chain transfer agent varies depending on the molecular weight and molecular weight distribution of the desired styrene-acrylic polymer segment. Specifically, the aromatic vinyl monomer and the (meth) acrylate monomer, and It is preferable to add in the range of 0.1-5 mass% with respect to the total amount of both reactive monomers.

  The polymerization temperature in the polymerization step (2) is not particularly limited, and is appropriately selected within a range in which the polymerization between the aromatic vinyl monomer and the (meth) acrylic acid ester monomer and the bonding to the polyester resin proceed. be able to. For example, the polymerization temperature is preferably 85 ° C. or higher and 125 ° C. or lower, more preferably 90 ° C. or higher and 120 ° C. or lower, and further preferably 95 ° C. or higher and 115 ° C. or lower.

  In the production of the styrene-acrylic modified polyester resin, it is practically preferable that the volatile organic substances from the emulsion such as the residual monomer amount after the polymerization step (2) are suppressed to 1,000 ppm or less, more preferably 500 ppm. Hereinafter, it is more preferably 200 ppm or less.

[Base particles]
The base particles constituting the toner particles according to the present invention contain a base resin composed of a styrene-acrylic copolymer, and if necessary, internal additives such as a colorant, a release agent, and a charge control agent. A resin other than the agent and the styrene-acrylic copolymer, for example, a crystalline substance may be contained.

[Styrene-acrylic copolymer]
As the polymerizable monomer used for forming the styrene-acrylic copolymer constituting the matrix resin, the fragrance used for forming the styrene-acrylic modified polyester resin constituting the bump resin described above is used. An aromatic vinyl monomer and a (meth) acrylic acid ester monomer can be mentioned. The above aromatic vinyl monomers and (meth) acrylic acid ester monomers can be used singly or in combination of two or more.
As the polymerizable monomer, together with the above aromatic vinyl monomer and (meth) acrylic acid ester monomer, acrylic acid, methacrylic acid, maleic anhydride, vinyl acetate, acrylamide, methacrylamide, acrylonitrile, Ethylene, propylene, butylene vinyl chloride, N-vinylpyrrolidone, butadiene and the like can also be used.
Moreover, a polyfunctional vinyl-type monomer can also be used as a polymerizable monomer with said aromatic vinyl monomer and (meth) acrylic acid ester monomer. Examples of the polyfunctional vinyl monomer include diacrylates such as ethylene glycol, propylene glycol, butylene glycol, and hexylene glycol; dimethacrylates of tertiary or higher alcohols such as divinylbenzene, pentaerythritol, and trimethylolpropane; Examples include trimethacrylate.
The copolymerization ratio of the polyfunctional vinyl monomer to the whole polymerizable monomer related to the matrix resin is usually 0.001 to 5% by mass, preferably 0.003 to 2% by mass, more preferably 0. 0.01 to 1% by mass.
The use of a polyfunctional vinyl monomer generates a gel component that is insoluble in tetrahydrofuran. The gel component is preferably 40% by mass or less, more preferably 20% by mass or less, based on the entire base resin. It is.

  The matrix resin described above preferably has a glass transition point of 30 to 60 ° C, more preferably 30 to 50 ° C. Moreover, it is preferable that a softening point is 80-110 degreeC, More preferably, it is 90-100 degreeC.

In the present invention, the glass transition point of the matrix resin is measured as follows.
Measured using a differential scanning calorimeter “Diamond DSC” (manufactured by Perkin Elmer). Specifically, 4.5 mg of a measurement sample (matrix resin) is precisely weighed to two decimal places and enclosed in an aluminum pan. And set in the DSC-7 sample holder. For the reference, an empty aluminum pan was used, and heat-cool-heat temperature control was performed at a measurement temperature of 0 to 200 ° C., a temperature increase rate of 10 ° C./min, and a temperature decrease rate of 10 ° C./min. Analysis is performed based on the data in Heat. The glass transition point is the value of the intersection of the baseline extension before the first endothermic peak rises and the tangent line that shows the maximum slope between the first endothermic peak rising portion and the peak apex.

In the present invention, the softening point of the matrix resin is measured as follows.
First, in an environment of 20 ° C. ± 1 ° C. and 50% ± 5% RH, 1.1 g of a measurement sample (matrix resin) is placed in a petri dish and left flat for 12 hours or more. 10A "(manufactured by Shimadzu Corporation) with a force of 3820 kg / cm ² for 30 seconds to produce a cylindrical molded sample having a diameter of 1 cm, and this molded sample was then subjected to 24 ° C. ± 5 ° C., 50% ± 20% In an environment of RH, a cylindrical die is produced by a flow tester “CFT-500D” (manufactured by Shimadzu Corporation) under the conditions of a load of 196 N (20 kgf), a starting temperature of 60 ° C., a preheating time of 300 seconds, and a heating rate of 6 ° C./min. The offset method temperature T _offset was measured from the hole (1 mm diameter x 1 mm) using a piston with a diameter of 1 cm from the end of preheating and measured at a setting of an offset value of 5 mm by the melting temperature measurement method of the temperature rising method. Is the softening point of the matrix resin.

In the present invention, the weight average molecular weight (Mw) of the base resin is preferably 5,000 to 50,000.
When the weight average molecular weight of the base resin is in the above range, the fixability can be satisfied.

In the present invention, the weight average molecular weight of the base resin is measured as follows.
Measured by gel permeation chromatography (GPC), specifically, using an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation), the column temperature at 40 ° C. While being held, tetrahydrofuran (THF) as a carrier solvent was flowed at a flow rate of 0.2 mL / min, and the measurement sample (matrix resin) was treated at room temperature for 5 minutes using an ultrasonic disperser at a concentration of 1 mg / mL. Then, the sample solution is obtained by processing with a membrane filter having a pore size of 0.2 μm, and 10 μL of this sample solution is injected into the apparatus together with the above carrier solvent, and a refractive index detector (RI detection) The molecular weight distribution of the sample is detected using a monodisperse poly It is calculated using a calibration curve measured using styrene standard particles. Ten polystyrenes are used for calibration curve measurement.

[Colorant]
When the base particles contain a colorant, as the colorant, for example, carbon black, a magnetic substance, a dye, other pigments, and the like can be arbitrarily used.
As the carbon black, channel black, furnace black, acetylene black, thermal black, lamp black and the like can be used.
As the magnetic material, ferromagnetic metals such as iron, nickel and cobalt, alloys containing these metals, and compounds of ferromagnetic metals such as ferrite and magnetite can be used.
As the pigment, C.I. I. Pigment Red 2, 3, 5, 7, 15, 16, 48: 1, 48: 3, 53: 1, 57: 1, 81: 4, 122, 123, 139, 144, 149, 166, 177, 178, 208, 209, 222, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 3, 9, 14, 17, 35, 36, 65, 74, 83, 93, 94, 98, 110, 111, 138, 139, 153, 155, 180, 181, 185, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 15: 4, 60, and phthalocyanine pigments whose central metal is zinc, titanium, magnesium, or the like can be used, and a mixture thereof can also be used. As the dye, C.I. I. Solvent Red 1, 3, 14, 17, 17, 22, 22, 49, 51, 52, 58, 63, 87, 111, 122, 127, 128, 131, 145, 146, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 176, 179, pyrazolotriazole Azo dyes, pyrazolotriazole azomethine dyes, pyrazolone azo dyes, pyrazolone azomethine dyes, 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, etc. can be used, and mixtures thereof can also be used.

  The content ratio of the colorant is preferably 1 to 30% by mass, more preferably 2 to 20% by mass with respect to the total amount of the resin constituting the toner particles.

〔Release agent〕
When the base particle contains a release agent, examples of the release agent include hydrocarbon waxes such as low molecular weight polyethylene wax, low molecular weight polypropylene wax, Fischer-Tropsch wax, microcrystalline wax, and paraffin wax. , Ester waxes such as carnauba wax, pentaerythritol behenate, behenyl behenate and behenyl citrate. These can be used individually by 1 type or in combination of 2 or more types.
As the releasing agent, it is preferable to use a releasing agent having a melting point of 50 to 95 ° C. from the viewpoint of reliably obtaining low-temperature fixability and releasing property of the toner.

  The content of the release agent is preferably 2 to 20% by mass, more preferably 3 to 18% by mass, and further preferably 4 to 15% by mass with respect to the total amount of the resin constituting the toner particles.

(Charge control agent)
When the base particles contain a charge control agent, various known charge control agents can be used.
As the charge control agent, various known compounds that can be dispersed in an aqueous medium can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, fourth compounds. Examples include quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.

  The content ratio of the charge control agent is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass with respect to the total amount of the resin constituting the toner particles.

[Toner Production Method]
From the viewpoint of forming a plurality of bumps in a specific shape on the surface of the base particle, the toner of the present invention is colored with fine particles of the base resin dispersed in an aqueous medium (hereinafter also referred to as “base resin fine particles”). The fine particles of the agent (hereinafter also referred to as “colorant fine particles”) and the like are aggregated and fused to form base particles, and the bump resin fine particles (hereinafter also referred to as “bump resin fine particles”) are formed on the surface of the base particles. The toner particles are preferably produced by an emulsion polymerization aggregation method in which toner particles are obtained by agglomeration and fusion.

Specifically showing an example of the case where the toner of the present invention is produced by an emulsion polymerization aggregation method,
(1-1) Bump resin fine particle dispersion preparing step of preparing a dispersion in which bump resin fine particles are dispersed in a bump resin in an aqueous medium,
(1-2) A matrix resin polymerization step for preparing a dispersion in which the matrix resin fine particles are dispersed by forming fine particles of the matrix resin by polymerization in an aqueous medium,
(1-3) Colorant fine particle dispersion preparation step for preparing a dispersion in which colorant fine particles are dispersed in an aqueous medium.
(2) A base particle forming step of forming base particles by aggregating the base resin fine particles and the colorant fine particles in an aqueous medium,
(3) To a toner particle having a plurality of bumps by adding a bump resin fine particle dispersion in an aqueous medium in which the base particles are dispersed, and aggregating and fusing the bump resin fine particles on the surface of the base particles. Bump formation process to form,
(4) An aging step of adjusting the shape of the toner particles by aging with heat energy;
(5) a cleaning step of separating the toner particles from the toner particle dispersion (aqueous medium) and removing the surfactant from the toner particles;
(6) a drying step of drying the washed toner particles;
Consisting of, if necessary,
(7) An external additive adding step of adding an external additive to the dried toner particles can be added.

(1-1) Bump Resin Fine Particle Dispersion Preparation Step In this bump resin fine particle dispersion preparation step, the bump resin fine particle dispersion is prepared by applying a surfactant by, for example, ultrasonic dispersion or bead mill dispersion. It can be obtained by the added aqueous dispersion method.

The average particle diameter of the bump resin fine particles obtained in this bump resin fine particle dispersion preparation step is preferably, for example, 100 to 300 nm in terms of volume-based median diameter (D ₅₀ ).
When the average particle diameter of the resin fine particles for bump is within the above range, the diameter of the bump formed on the surface of the base particle can be set to 100 to 500 nm.
In the present invention, the volume-based median diameter of the resin fine particles for bumps is measured using “UPA-150” (manufactured by Microtrack).

  In the present invention, the “aqueous medium” refers to a medium comprising 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran, and alcohol-based organic solvents that do not dissolve the resulting resin are preferable.

[Surfactant]
A dispersion stabilizer is preferably added to the aqueous medium in order to prevent aggregation of dispersed fine particles.
As the dispersion stabilizer, various known surfactants such as a cationic surfactant, an anionic surfactant, and a nonionic surfactant can be used.
Specific examples of the cationic surfactant include dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl anonium bromide and the like.
Specific examples of nonionic surfactants include dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, norylphenyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, styrylphenyl poly Examples thereof include oxyethylene ether and monodecanoyl sucrose.
Specific examples of the anionic surfactant include aliphatic soaps such as sodium stearate and sodium laurate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, polyoxyethylene (2) sodium lauryl ether sulfate and the like. it can.
The above surfactants can be used singly or in combination of two or more as desired.

(1-2) Matrix Resin Polymerization Step In this matrix resin polymerization step, fine particles are formed from the matrix resin, and this is used for the matrix particle formation step.
Specifically, the matrix resin fine particles are released from the polymerizable monomer for forming the matrix resin in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less as necessary. Add a monomer solution in which toner particle components such as an agent and a charge control agent are dissolved or dispersed, add mechanical energy to form droplets, and then add a water-soluble radical polymerization initiator. The polymerization reaction is allowed to proceed in the droplet. Note that an oil-soluble polymerization initiator may be contained in the droplet. In such a matrix resin polymerization process, mechanical energy is imparted and forcedly emulsified (formation of droplets) is essential. Examples of the means for applying mechanical energy include means for applying strong stirring or ultrasonic vibration energy such as homomixer, ultrasonic wave, and manton gorin.

  The matrix resin fine particles formed in the matrix resin polymerization step can be composed of two or more layers composed of resins having different compositions. In this case, an emulsion polymerization process (first-stage polymerization) according to a conventional method is used. The polymerization initiator and the polymerizable monomer are added to the dispersion liquid of the first resin fine particles prepared by the above method, and the system is polymerized (second-stage polymerization).

  When using a surfactant in the matrix resin polymerization step, the same surfactant as the surfactant that can be used in the above-mentioned bump resin fine particle dispersion preparation step is used as the surfactant, for example. be able to.

In addition to the matrix resin, the matrix particles according to the present invention may contain an internal additive such as a release agent, a charge control agent, and magnetic powder, if necessary. For example, in this matrix resin polymerization step, can be introduced into the matrix particles by dissolving or dispersing in advance in a monomer solution for forming the matrix resin.
In addition, for such an internal additive, a dispersion of internal additive fine particles consisting of only the internal additive is separately prepared, and the internal additive fine particles are aggregated together with the base resin fine particles and the colorant fine particles in the base particle forming step. Although it can also introduce | transduce into a base particle, it is preferable to employ | adopt the method introduced beforehand in the resin polymerization process for bases.

(Polymerization initiator)
As the polymerization initiator used in the matrix resin polymerization step, the same ones as described above can be used.

[Chain transfer agent]
In the matrix resin polymerization step, a generally used chain transfer agent can be used for the purpose of adjusting the molecular weight of the matrix resin. As the chain transfer agent, the same ones as described above can be used.

The average particle size of the matrix resin fine particles obtained in the matrix resin polymerization step is preferably in the range of, for example, 50 to 500 nm in terms of volume-based median diameter.
In the present invention, the volume-based median diameter of the matrix resin fine particles is measured using “UPA-150” (manufactured by Microtrack).

(1-3) Colorant fine particle dispersion preparation step The colorant fine particle dispersion can be prepared by dispersing a colorant in an aqueous medium. The colorant dispersion treatment is preferably performed in a state where the surfactant concentration in the aqueous medium is not less than the critical micelle concentration (CMC) since the colorant is uniformly dispersed. Various known dispersers can be used as a disperser used for the dispersion treatment of the colorant.
Examples of the surfactant used include the same surfactants as those described above.

The dispersion diameter of the colorant fine particles in the colorant fine particle dispersion prepared in the colorant fine particle dispersion preparing step is preferably 10 to 300 nm in terms of volume-based median diameter.
In the present invention, the dispersion diameter of the colorant fine particles is measured using a microtrack particle size distribution measuring apparatus “UPA-150” (manufactured by Nikkiso Co., Ltd.).

  When a surfactant is used in this colorant fine particle dispersion preparation step, the same surfactant as the surfactant that can be used in the above-mentioned bump resin fine particle dispersion preparation step, for example, is used. Can be used.

(2) Base Particle Formation Step In this base particle formation step, fine particles of toner particle constituent components such as a release agent and a charge control agent may be aggregated together with the base resin fine particles and the colorant fine particles, if necessary. it can.

  As a specific method for aggregating and fusing the matrix resin fine particles and the colorant fine particles, an aggregating agent is added to an aqueous medium so as to have a critical aggregation concentration or higher, and then the glass transition point or higher of the matrix resin fine particles is exceeded. In addition, by heating the mixture to a temperature equal to or higher than the melting peak temperature (° C.) of the mixture, the salting out of the fine particles such as the matrix resin fine particles and the colorant fine particles proceeds, and at the same time, the fusion is proceeded in parallel. This is a method in which when the particles have grown to a desired particle size, an aggregation terminator is added to stop the particle growth, and heating is continued to control the particle shape as necessary.

  In this method, the time allowed to stand after adding the flocculant is shortened as much as possible, and immediately above the glass transition point of the resin fine particles related to the base resin, and above the melting peak temperature (° C.) of these mixtures. Heating to temperature is preferred. The reason for this is not clear, but depending on the standing time after salting out, the aggregation state of the particles may fluctuate and the particle size distribution may become unstable, and the surface properties of the fused particles may vary. This is because there is concern about the occurrence. The time until this temperature rise is usually preferably within 30 minutes, and more preferably within 10 minutes. Moreover, it is preferable that it is 1 degree-C / min or more as a temperature increase rate. The upper limit of the heating rate is not particularly specified, but is preferably 15 ° C./min or less from the viewpoint of suppressing the generation of coarse particles due to rapid progress of fusion. Furthermore, after the reaction system reaches a temperature equal to or higher than the glass transition point, it is important to continue the fusion by maintaining the temperature of the reaction system for a certain time. Thereby, the growth and fusion of the base particles can be effectively advanced, and the durability of the finally obtained toner particles can be improved.

[Flocculant]
The flocculant used in the base particle forming step is not particularly limited, but a material selected from metal salts is preferably used. Examples of the metal salt include monovalent metal salts such as alkali metal salts such as sodium, potassium and lithium; divalent metal salts such as calcium, magnesium, manganese and copper; and trivalent metal salts such as iron and aluminum. Etc. Specific metal salts can include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, and the like. It is particularly preferable to use a divalent metal salt. These can be used individually by 1 type or in combination of 2 or more types.

  When using a surfactant in the base particle forming step, use the same surfactant as the surfactant that can be used in the above-described bump resin fine particle dispersion preparation step, for example. Can do.

The average particle diameter of the base particles obtained in this base particle forming step is, for example, preferably a volume-based median diameter (D ₅₀ ) of 4 to 10 μm, more preferably 5 to 7 μm.
In the present invention, the volume-based median diameter of the base particles is measured by “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.).

(3) Bump formation step In this bump formation step, the bump resin fine particle dispersion is added to the base particle dispersion to agglomerate and fuse the bump resin fine particles to the surface of the base particle, thereby forming the surface of the base particle. The toner particles are formed by forming bumps.
Specifically, the dispersion of the base particles is added with the bump resin fine particle dispersion while maintaining the temperature in the base particle formation process, and the bump resin fine particles are slowly added to the base over several hours while continuing the heating and stirring. By agglomerating and fusing the particle surface, bumps are formed on the surface of the base particle to form toner particles. The agglomeration and fusion time is preferably 3 to 6 hours, particularly preferably 4 to 5 hours.

Bumps are obtained by adding resin particles for bumps made of styrene-acrylic modified polyester resin in which a styrene-acrylic polymer segment is bonded to a polyester segment to a dispersion of base particles made of styrene-acrylic copolymer. When resin fine particles adhere to the surface of a base particle composed of a styrene-acrylic copolymer, the compatibility of the styrene-acrylic portion with a small difference in SP value (solubility parameter value) proceeds, while the SP value It is formed when the compatibility of the polyester portion having a large difference becomes difficult to proceed. As a result, a bump is formed by a polyester portion on the surface of the base particle.
Here, the SP value is a solubility parameter value (δ) at 25 ° C., and is calculated from the molecular cohesive energy density ΔE of the substance and the molecular capacity V from δ = (ΔE / V) ^1/2 Is a useful measure for predicting the solubility of a substance. The SP value indicates that the polarity is higher as the numerical value is larger, and the polarity is lower as the numerical value is smaller. And when mixing 2 types of substances, so that the difference of both SP value is small, so that solubility becomes large.
Therefore, the height of the bump is controlled by the difference in SP value between the styrene-acrylic modified polyester resin and the styrene-acrylic copolymer. If the SP value is large, a bump with a higher height is formed. If the value difference is small, a bump with a lower height is formed. In the toner of the present invention, bumps are formed by making the SP value of the styrene-acrylic modified polyester resin higher than the SP value of the styrene-acrylic copolymer.

  SP value is the composition of the polymerizable monomer used to form the styrene-acrylic copolymer constituting the base particles, the molecular weight of the styrene-acrylic copolymer, and the styrene-acrylic modified polyester resin constituting the bump. It can be controlled by the content ratio of the styrene-acrylic polymer segment (styrene-acrylic modification rate), the molecular weight, the composition of the aromatic vinyl monomer and the (meth) acrylic acid ester monomer.

  Further, the bump diameter can be controlled by the particle diameter of the resin fine particles for bump and the aggregation and fusion time in the bump forming process. For example, if the agglomeration and fusion time is long, uniting of the bumps easily proceeds and the diameter increases.

  Furthermore, the distribution density of the bumps can be controlled by the addition amount of the resin fine particle dispersion for bumps. It is preferable to add the resin fine particle dispersion for bumps so as to be 10 to 30% by mass, and more preferably 5 to 20% by mass with respect to the total amount of the resin for the matrix in terms of solid content.

(4) Ripening Step After the host particle forming step and the bump forming step, the aging step is performed to control the heating temperature and control the shape of the toner particles and the bump shape.
The aging time is preferably 1 to 8 hours, particularly preferably 2 to 5 hours.

(5) Washing step to (6) Drying step The washing step and the drying step can be performed by employing various known methods.

(7) External additive addition step This external additive addition step is a step of adding and mixing external additives as necessary to the dried toner particles.
The toner particles produced through the steps up to the drying step can be used as toner particles as they are, but an external additive is added from the viewpoint of further improving the charging performance, fluidity, and cleaning properties of the toner. It is preferable to add. In the toner of the present invention, since the external additive is attached between the bumps formed on the surface of the base particle, it is suppressed that the impact force is directly received by the collision with the carrier and the toner. , The burying of the external additive is suppressed. Therefore, charging performance, fluidity, and cleaning properties as a toner are ensured, and high durability can be obtained.

(External additive)
As external additives, those that have been hydrophobized with a long-chain alkylsilane from the viewpoint of ensuring the stability of the charged state, and also enter between the bumps formed on the surface of the base particle from the viewpoint of ensuring durability. It is preferable to add one having a size that can be handled. In addition, the chargeability, fluidity, and cleaning properties can be controlled over a long period of time by optimally combining external additives having small, medium, and large particle diameters.

[Specific hydrophobized silica fine particles]
Specifically, it is preferable to use specific hydrophobized silica fine particles having an average particle diameter of 20 to 40 nm that have been subjected to a hydrophobization treatment with a long-chain alkylsilane.
By adding specific hydrophobized silica fine particles to the toner particles, the hydrophobization treatment is performed with a long-chain alkylsilane, so that the stability of the charged state is basically secured and the specific hydrophobic When the silica fine particles enter between the bumps formed on the surface of the base particle, the specific hydrophobized silica fine particles directly exert an impact force by collision between carrier particles and toner particles or between toner particles. Since receiving is suppressed, embedding of the specific hydrophobized silica fine particles in the toner particles is suppressed.

In the present invention, the average particle size of specific hydrophobized silica fine particles is measured as follows.
Using a scanning electron microscope “JSM-7401F” (manufactured by JEOL), observation is performed 30,000 times, image processing is performed from SEM image data, diameters of 10 fine particles are measured, and an average value is calculated.

  As the long-chain alkylsilane as the hydrophobizing agent for the specific hydrophobized silica fine particles, a general one can be used, and examples thereof include octadecyltrimethoxysilane and hexadecyltrimethoxysilane. The long chain alkylsilane preferably has 6 to 16 carbon atoms. In the case where the carbon number of the long-chain alkylsilane is less than 6, there is a risk that the stability of the charged state is lowered in a high temperature and high humidity environment. On the other hand, when the carbon number of the long-chain alkylsilane exceeds 16, developability is lowered.

The addition ratio of the specific hydrophobized silica fine particles is preferably 0.85 to 1.05 parts by mass with respect to 100 parts by mass of the toner particles.
When the addition ratio of the specific hydrophobized silica fine particles is too small, fog may occur in the formed image. On the other hand, when the ratio of the specific hydrophobized silica fine particles added is excessive, raindrop-like image defects may occur due to liberation of external additives.

[Large diameter silica fine particles]
In the present invention, it is more preferable to use large-diameter silica fine particles having a particle size of 60 to 120 nm together with specific hydrophobic silica fine particles as an external additive. The large-diameter silica fine particles may be subjected to a surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil, or the like.
By further including an external additive composed of large-diameter silica fine particles, the cleaning property can be further improved, and a stable cleaning property can be obtained at the time of printing.

The addition ratio of the large silica fine particles is preferably 0.8 to 1.3 parts by mass with respect to 100 parts by mass of the toner particles.
When the addition ratio of large-diameter silica fine particles is too small, sufficient cleaning properties cannot be obtained. On the other hand, when the addition ratio of the large-diameter silica fine particles is excessive, there is a risk of inhibiting the charge rising.

[Small-diameter silica fine particles or small-diameter titania fine particles]
In the present invention, as the external additive, together with specific hydrophobized silica fine particles and large silica fine particles, small-diameter silica fine particles having a particle diameter of 5 to 20 nm or small-diameter titania fine particles having a particle diameter of 5 to 20 nm are used. It is particularly preferred. The small-diameter silica fine particles or small-diameter titania fine particles may be subjected to surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil, or the like.
By further including an external additive consisting of small-diameter silica fine particles or small-diameter titania fine particles, sufficient charge rising performance can be ensured.

The addition ratio of the small diameter silica fine particles or the small diameter titania fine particles is preferably 0.50 to 0.80 parts by mass with respect to 100 parts by mass of the toner particles.
In the case where the addition ratio of the small-diameter silica fine particles or the small-diameter titania fine particles is too small, it is not possible to ensure sufficient charge rising performance. On the other hand, when the addition ratio of the small-diameter silica fine particles or the small-diameter titania fine particles is excessive, a raindrop-like image defect may occur.

In the present invention, the particle diameters of the large-diameter silica fine particles, the small-diameter silica fine particles, and the small-diameter titania fine particles are measured as follows.
Using a scanning electron microscope “JSM-7401F” (manufactured by JEOL), 30,000 times observation is performed, image processing is performed from SEM image data, and the diameter of the fine particles is measured.

  In the case of using large-diameter silica fine particles, small-diameter silica fine particles, or small-diameter titania fine particles as external additives, the large-diameter silica fine particles have an average particle diameter of 60 to 120 nm, and the small-diameter silica fine particles and small-diameter titania fine particles The one having an average particle diameter of 5 to 20 nm is used. These average particle diameters are measured in the same manner as the method for measuring the average particle diameter of the specific hydrophobized silica fine particles described above.

  In the present invention, other external additives may be added as external additives in addition to the specific hydrophobized silica fine particles, large-diameter silica fine particles, small-diameter silica fine particles, or small-diameter titania fine particles. Examples of other external additives include inorganic oxide fine particles such as alumina fine particles, inorganic stearate compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles, and inorganic titanic acid such as strontium titanate and zinc titanate. Compound fine particles are exemplified. These other external additives are preferably those subjected to surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like from the viewpoint of heat-resistant storage stability and environmental stability.

The coating ratio of the external additive as described above is preferably 70 to 90%.
If the coating ratio of the external additive is too small, fog may occur in the formed image. On the other hand, when the coating ratio of the external additive is excessive, a raindrop-like image defect may occur due to liberation of the external additive.

In the present invention, the coating ratio of the external additive is determined as follows.
That is, the total volume of the toner is determined with a density of 1.05 g / m ² per 100 parts by mass. From the value, the diameter of the toner particles is used to calculate the number of particles. The total surface area of the toner particles is calculated by multiplying the toner particle surface area per particle by the number of particles. Further, the total area projected by the particle diameter of the external additive is calculated from the number of parts by mass of the external additive with respect to 100 parts by mass of the toner, and the coating ratio is calculated by the following equation (1).
Formula (1): coverage ratio (%) = projected area of external additive particles / total surface area of toner particles

As a method for adding the external additive, there is a dry method in which the external additive is added to the dried toner particles as a powder and mixed. As a mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill is used. Is mentioned.
In the present invention, when the large-diameter silica fine particles are used as the external additive, the large-diameter silica fine particles are added before the specific hydrophobized silica fine particles, small-diameter silica fine particles, small-diameter titania fine particles, and other external additives. It is preferable. Since large-size external additives are difficult to be fixed to toner particles, the addition of large-diameter silica particles first suppresses the generation of external additives, thereby ensuring high durability. can get.

In the present invention, the elemental analysis of the external additive can be performed by energy dispersive X-ray analysis (EDS).
Specifically, a 10,000 times toner particle image is obtained using an energy dispersive X-ray spectrometer “JED-2300” (manufactured by JEOL) attached to a scanning electron microscope “JSM-7401F” (manufactured by JEOL). The element can be identified by applying a voltage of 15 kV to point 10 and performing point analysis with an intensity of about 10% of the irradiation current.

[Average particle diameter of toner particles]
The average particle diameter of the toner particles constituting the toner of the present invention is preferably, for example, 4 to 8 μm in volume-based median diameter (D ₅₀ ). For example, when the toner particles are produced by an emulsion polymerization aggregation method, the average particle diameter can be controlled by the concentration of the aggregating agent used, the amount of the organic solvent added, the fusing time, and the polymer composition.
When the volume-based median diameter is in the above range, for example, a very minute dot image at a level of 1200 dpi (dpi; number of dots per inch (2.54 cm)) can be faithfully reproduced.

In the present invention, the volume-based median diameter of toner particles is a measuring device in which a computer system equipped with data processing software “Software V3.51” is connected to “Coulter Multisizer 3” (manufactured by Beckman Coulter). Measured and calculated.
Specifically, 0.02 g of a measurement sample (toner) was added to 20 mL of a surfactant solution (for example, a surfactant obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles). Solution) and ultrasonically disperse for 1 minute to prepare a toner particle dispersion. This toner particle dispersion is placed in “ISOTONII” (manufactured by Beckman Coulter) in the sample stand. Pipette into a beaker until the displayed concentration of the measuring device is 8%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measuring apparatus, the frequency value is calculated by setting the number of measured particle counts to 25000 and the aperture diameter to 100 μm, and the particle diameter of 50% from the larger volume integrated fraction is the volume-based median diameter.

[Average circularity of toner particles]
In the toner of the present invention, the arithmetic average value of the circularity represented by the following formula (T) is 0.850 to 0.990 from the viewpoint of improving the transfer efficiency of the individual toner particles constituting the toner. Is preferred.
Formula (T): Circularity = perimeter of perfect circle having projection area equivalent to particle projection image / perimeter of particle projection image

In the present invention, the average circularity of toner particles is measured using “FPIA-2100” (manufactured by Sysmex).
Specifically, the measurement sample (toner) is moistened with an aqueous surfactant solution, and ultrasonic dispersion is performed for 1 minute. After dispersion, the measurement sample is used in the measurement condition HPF (high magnification imaging) mode using “FPIA-2100”. The measurement is performed at an appropriate concentration of 3000 to 10,000 HPF detections. Within this range, reproducible measurement values can be obtained.

  From the above, in the toner of the present invention, basically, a plurality of bumps are formed on the surface of the base particles constituting the toner particles, so that the bumps are caught between the blade and the photoreceptor substrate, Since the toner particles are prevented from slipping through, cleaning properties are ensured even during printing durability. In the toner of the present invention, when an external additive is added, a plurality of bumps having a height approximately equal to the particle size of the external additive are formed, so that the external additive is a base material. By entering between the bumps formed on the particle surface, the external additive is prevented from receiving an impact force directly due to the collision between the toner particles and the carrier particles or the collision between the toner particles. Since transfer of the additive to the carrier and embedding in the toner particles are suppressed, developability and transferability are ensured even during printing durability. In the present invention, even if no external additive is added, the adhesion between the toner particles or between the carrier particles and the toner particles is reduced and the fluidity is improved. It is also expected as a toner constituting the toner. Furthermore, in the toner of the present invention, when specific hydrophobized silica fine particles hydrophobized with a long-chain alkylsilane are added as external additives, the stability of the charged state is ensured and the specific Hydrophobized silica fine particles enter between the bumps formed on the surface of the base particle, so that the specific hydrophobized silica fine particles directly exert impact force due to collision between toner particles and carrier particles or between toner particles. Therefore, the embedding of the specific hydrophobized silica fine particles in the toner particles is suppressed, and further developability and transferability are ensured even at the time of printing. As described above, according to the toner of the present invention, high durability can be obtained while sufficient reliability such as stability of charge state, developability, transferability, and cleaning property is ensured.

[Two-component developer]
The toner of the present invention can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer.
As the carrier, for example, magnetic particles made of conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Among these, ferrite particles Is preferably used.

The apparent density of the carrier is preferably 1.0 to 2.0 g / cm ³ .
When the apparent density of the carrier is in the above range, it is possible to achieve both durability and charge rising property.
When the apparent density of the carrier is less than 1.0 g / cm ³ , the strength may be small. On the other hand, when the apparent density of the carrier is larger than 2.0 g / cm ^3, there is a possibility that charging rise is inhibited.

In the present invention, the apparent density of the carrier is calculated as follows.
Using a Kawakita type bulk density measuring machine (IH2000 type), the carrier was placed on a 120 mesh sieve and dropped for 90 seconds at a vibration strength of 6, and then the vibration was stopped and left to stand for 30 seconds. Volume).

As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a resin-dispersed carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.
The carrier particles preferably have a volume average particle diameter of 15 to 100 μm, and more preferably 25 to 80 μm.

  From the above, according to the two-component developer of the present invention, it is possible to realize high durability while achieving high reliability by comprising the toner and a carrier having an apparent density in a specific range. .

(Image forming method)
The toner of the present invention can be used in a general electrophotographic image forming method. In addition, as an image forming apparatus in which such an image forming method is performed, for example, a photosensitive member which is an electrostatic latent image carrier, and a uniform potential is applied to the surface of the photosensitive member by corona discharge having the same polarity as the toner. A charging unit; an exposure unit that forms an electrostatic latent image by performing image exposure on the surface of the uniformly charged photosensitive member based on image data; A developing unit that visualizes the electrostatic latent image to form a toner image, a transfer unit that transfers the toner image to a transfer material via an intermediate transfer member as necessary, and a fixing that fixes the toner image on the transfer material What has a means can be used. Among image forming apparatuses having such a configuration, a color image forming apparatus having a configuration in which image forming units related to a plurality of photoconductors are provided along the intermediate transfer body, in particular, the photoconductors are arranged in series on the intermediate transfer body. It can be suitably used for the tandem type color image forming apparatus.

  From the above, according to the image forming method of the present invention, a high-quality image can be formed over a long period of time by using the two-component developer.

  As mentioned above, although embodiment of this invention was described concretely, embodiment of this invention is not limited to said example, A various change can be added.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Toner Particle Preparation Example 1]
(1) Preparation of matrix resin fine particles (A1) dispersion (1-1) First-stage polymerization Anionic surface activity in advance in a reaction vessel equipped with a stirrer, temperature sensor, temperature controller, cooling pipe and nitrogen introducing device A surfactant solution in which 2.0 parts by mass of the agent “sodium lauryl sulfate” was dissolved in 2900 parts by mass of ion-exchanged water was added, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. It was.
After adding 9.0 parts by mass of a polymerization initiator “potassium persulfate: KPS” to this surfactant solution and adjusting the internal temperature to 78 ° C.,
Styrene 540 parts by weight n-butyl acrylate 270 parts by weight Methacrylic acid 65 parts by weight n-octyl mercaptan 17 parts by weight of solution (1) was added dropwise over 3 hours, and after completion of the addition, heating and stirring at 78 ° C. for 1 hour Thus, polymerization (first stage polymerization) was performed to prepare “resin fine particle (a1) dispersion”.

(1-2) Second-stage polymerization: formation of intermediate layer In a flask equipped with a stirrer,
Styrene 94 parts by weight n-butyl acrylate 60 parts by weight Methacrylic acid 11 parts by weight n-octyl mercaptan 5 parts by weight Paraffin wax (melting point: 73 ° C.) 51 parts by weight as a release agent was added, A monomer solution (2) was prepared by heating to 85 ° C. and dissolving.

  On the other hand, a surfactant solution in which 2 parts by mass of the anionic surfactant “sodium lauryl sulfate” was dissolved in 1100 parts by mass of ion-exchanged water was heated to 90 ° C., and “resin fine particles (a1)” was added to this surfactant solution. After adding 28 parts by mass of the “dispersion liquid” in terms of the solid content of the resin fine particles (a1), the monomer solution (2) was added by a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. ) Is mixed and dispersed for 4 hours to prepare a dispersion containing emulsified particles having a dispersed particle diameter of 350 nm. In this dispersion, 2.5 parts by mass of the polymerization initiator “KPS” is dissolved in 110 parts by mass of ion-exchanged water. An aqueous initiator solution was added, and the system was heated and stirred at 90 ° C. for 2 hours to conduct polymerization (second stage polymerization) to prepare “resin fine particle (a11) dispersion”.

(1-3) Third Step Polymerization: Formation of Outer Layer Initiator aqueous solution in which 2.5 parts by mass of polymerization initiator “KPS” is dissolved in 110 parts by mass of ion-exchanged water in the “resin fine particle (a11) dispersion”. And at a temperature of 80 ° C.
Styrene 230 mass parts n-butyl acrylate 100 mass parts n-octyl mercaptan Solution (3) which consists of 5.2 mass parts was dripped over 1 hour. After completion of the dropwise addition, polymerization (third stage polymerization) was carried out by heating and stirring for 3 hours. Thereafter, the mixture was cooled to 28 ° C., and the matrix resin (styrene-acrylic copolymer) fine particles (A1) having a median diameter (D ₅₀ ) of 180 nm on a volume basis were dispersed in the anionic surfactant solution. A resin fine particle (A1) dispersion ”was prepared.

(2) Preparation of resin fine particles for bump (B1) dispersion (2-1) Preparation of polyester resin (a) 2 mol of bisphenol A propylene oxide was added to a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introducing tube. 316 parts by mass of product, 80 parts by mass of terephthalic acid, 34 parts by mass of maleic anhydride, and 2 parts by mass of titanium tetraisopropoxide as a polycondensation catalyst are added in 10 portions, and water is produced at 200 ° C. under a nitrogen stream. The reaction was carried out for 10 hours while distilling off. Next, the reaction was carried out under reduced pressure of 13.3 kPa (100 mmHg), and the mixture was taken out when the softening point reached 104 ° C. This is designated as “polyester resin (a)”. The “polyester resin (a)” had a glass transition point of 65 ° C., a number average molecular weight (Mn) of 4500, and a weight average molecular weight (Mw) of 13500.

(2-2) Preparation of Bump Resin (B1) In an autoclave reaction vessel equipped with a thermometer and a stirrer, 430 parts by mass of xylene and 430 parts by mass of the polyester resin (a) were dissolved, and after substitution with nitrogen, styrene A mixed solution of 7.1 parts by weight, 1.8 parts by weight of 2-ethylhexyl acrylate, 0.062 parts by weight of di-t-butyl peroxide, and 100 parts by weight of xylene was dropped and polymerized at 170 ° C. for 3 hours. Hold at temperature for 30 minutes. Subsequently, the solvent was removed to obtain a “bump resin (styrene-acryl-modified polyester resin) (B1)”.

(2-3) Preparation of Bump Resin Fine Particles (B1) Dispersion Solution 100 parts by mass of the obtained “bump resin (B1)” was dissolved in 400 parts by mass of ethyl acetate (manufactured by Kanto Chemical Co., Inc.) and prepared in advance. After mixing with 638 parts by weight of a 0.26% by weight sodium lauryl sulfate solution, the mixture was subjected to ultrasonic dispersion with an ultrasonic homogenizer “US-150T” (manufactured by Nippon Seiki Seisakusho) at V-LEVEL 300 μA for 30 minutes while stirring. Using a diaphragm vacuum pump “V-700” (manufactured by BUCHI) while being heated to 40 ° C., ethyl acetate was completely removed while stirring under reduced pressure for 3 hours to obtain a median diameter (D ₅₀ ) obtained a “bump resin fine particle (B1) dispersion” having a solid content of 13.5% by mass in which the bump resin fine particles (B1) having a thickness of 200 nm were dispersed.

(3) Preparation of Colorant Fine Particle Dispersion Solution 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 “Mogal L” (manufactured by Cabot) is gradually added, and then dispersed using a stirrer “Claremix” (manufactured by M Technique). Then, a “colorant fine particle dispersion” in which the colorant fine particles were dispersed was prepared. The particle diameter of the colorant fine particles was measured using a Microtrac particle size distribution analyzer “UPA-150” (manufactured by Nikkiso Co., Ltd.), and was 117 nm.

(4) Base particle forming step, bump forming step, aging step In a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube, 288 parts by mass of “matrix resin fine particles (A1) dispersion” in terms of solid content, ions After adding 2000 parts by mass of exchange water, 5 mol / liter sodium hydroxide aqueous solution was added to adjust pH to 10.
Thereafter, 40 parts by mass of “colorant fine particle dispersion” was added in terms of solid content. Next, an aqueous solution in which 60 parts by mass of magnesium chloride was dissolved in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. Thereafter, the temperature was raised after being allowed to stand for 3 minutes, and the temperature of the system was raised to 80 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 80 ° C. In this state, the average particle diameter of the base particles was measured with “Coulter Multisizer 3” (manufactured by Beckman Coulter), and when the median diameter (D ₅₀ ) on the volume basis reached 6.0 μm, 72 parts by mass of the resin fine particle (B1) dispersion "is added over 30 minutes in terms of solid content, and 190 parts by mass of sodium chloride is dissolved in 760 parts by mass of ion-exchanged water when the supernatant of the reaction solution becomes transparent. The aqueous solution was added to stop particle growth. Furthermore, the temperature is raised, and the mixture is heated and stirred at 90 ° C. for 2 hours to progress the particle fusing, and the aging treatment is performed, and the toner average circularity measuring device “FPIA-2100” (manufactured by Sysmex) (The number of detected HPFs is 4000). When the average circularity reached 0.945, it was cooled to 30 ° C. to prepare a “toner particle (1) dispersion” in which the toner particles (1) were dispersed. .

(5) Washing step, drying step The “toner particle (1) dispersion” was solid-liquid separated by a centrifugal separator to form a wet cake of toner particles (1). The wet cake was washed with ion-exchanged water at 35 ° C. until the electric conductivity of the filtrate reached 5 μS / cm with the centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). “Toner particles (1)” were produced by drying to 0.5 mass%. The obtained “toner particles (1)” were observed 10,000 times using a scanning electron microscope “JSM-7401F” (manufactured by JEOL), and bumps were measured. Table 1 shows the average height, average diameter, and average distribution density of the bumps.

[Toner Particle Preparation Examples 2 to 10]
In Preparation Example 1 of Toner Particles, (2) Bump Resin Fine Particles (B1) in Preparation of Dispersion (2-2) Bump Resin (B1) Preparation In Styrene, 2-ethylhexyl acrylate and di-t- “Bump resins (B2) to (B10)” were prepared in the same manner except that the addition amount of butyl peroxide was changed in accordance with Table 1, and “Bump Resin” instead of “Bump Resin (B1)”. Resin (B2) to (B10) ”and (4)“ Toner Particles ”in the same manner except that the aging time was changed according to Table 1 in the base particle forming step, bump forming step, and aging step. 2) to (10) "were produced. The obtained “toner particles (2) to (5) and (7) to (10)” were observed 10,000 times using a scanning electron microscope “JSM-7401F” (manufactured by JEOL), and bumps were measured. Table 1 shows the average height, average diameter, and average distribution density of the bumps. Note that no bumps were observed on the “toner particles (6)”.

[Toner Preparation Example 1]
(External additive addition process)
1.0 part by mass of large-diameter silica fine particles (average particle diameter: 80 nm) was added to 100 parts by mass of “toner particles (1)”, and the mixture was first mixed with a “Henschel mixer” (Mitsui Mining Co., Ltd.) for 5 minutes. Thereafter, 0.95 part by mass of medium-sized silica fine particles (average particle size: 30 nm) and small-diameter external additive fine particles (small-diameter silica fine particles) (average particle size: 16 nm) hydrophobized with long-chain alkylsilane (10 carbon atoms) ) 0.48 parts by mass were added and mixed for another 5 minutes. The obtained toner was passed through a sieve having an opening of 45 μm to remove coarse particles, and “Toner (1)” was produced.

[Toner Preparation Examples 2 to 5]
In “Toner Preparation Example 1”, “Toners (2) to (5)” were similarly used except that “Toner particles (2) to (5)” were used instead of “Toner particles (1)”. Produced.

[Toner Preparation Examples 6 to 7]
“Toners (6) to (7)” were respectively changed in the same manner as in Preparation Example 1 except that the addition amount of medium-sized silica fine particles (average particle size: 30 nm) was changed according to the addition amount shown in Table 2. Produced.

[Toner Preparation Examples 8 to 9]
In Toner Production Example 1, “Toner (8)” was used in the same manner except that the long-chain alkylsilane (carbon number 10) shown in Table 2 was used instead of the long-chain alkylsilane (carbon number 10) as the hydrophobizing agent for medium-sized silica fine particles. To (9) ".

[Toner Preparation Examples 10 to 11]
In “Toner Preparation Example 1”, “Toners (10) to (11)” were similarly changed except that the addition amount of large-diameter silica fine particles (average particle size: 80 nm) was changed according to the addition amount shown in Table 2. Produced.

[Toner Preparation Example 12]
In Toner Preparation Example 1, large-sized silica fine particles (average particle size: 80 nm), medium-sized silica fine particles (average particle size: 30 nm), and small-sized external additive fine particles (average particle size: 16 nm) were mixed together. Other than that, “Toner (12)” was produced in the same manner.

[Toner Preparation Example 13]
In “Toner Preparation Example 1”, “Toner (Small Particle)” was used in the same manner except that small diameter titania fine particles (average particle diameter: 20 nm) were used instead of small diameter external additive fine particles (small diameter silica fine particles) (average particle diameter: 16 nm). 13) ".

[Toner Preparation Examples 14 to 15]
“Toners (14) to (15)” were similarly prepared in Example 1 except that the addition amount of medium-sized silica fine particles (average particle size: 30 nm) was changed according to the addition amount shown in Table 2. Produced.

[Toner Preparation Examples 16 to 17]
In “Toner Preparation Example 1”, “Toners (16) to (17)” were similarly changed except that the addition amount of large-diameter silica fine particles (average particle size: 80 nm) was changed according to the addition amount shown in Table 2. Produced.

[Toner Preparation Example 18]
In Toner Preparation Example 1, “Toner” was used in the same manner except that hexamethyldisilazane (HMDS) was used in place of long-chain alkylsilane (carbon number 10) as a hydrophobizing agent for medium-sized silica fine particles. 18) ".

[Comparative Toner Preparation Examples 1 to 5]
In “Toner Preparation Example 1”, “Comparative Toners (1) to (5)” is similarly used except that “Toner Particles (6) to (10)” are used instead of “Toner Particles (1)”. Was made.

[Preparation Examples 1-11, 14-20 of Two-Component Developer and Preparation Examples 1-5 of Two-Component Developer for Comparison]
With respect to the obtained “toners (1) to (18)” and “comparative toners (1) to (5)”, a ferrite carrier (apparent density 1.75 g / cm ³ ) was added to a toner concentration of 6% by mass. Thus, “two-component developers (1) to (11), (14) to (20)” and “comparative two-component developers (1) to (5)” were prepared.

[Two-component developer production example 12]
The resulting “toner (1)” was mixed with a ferrite carrier (apparent density of 2.00 g / cm ³ ) so that the toner concentration was 6% by mass, and “two-component developer (12)” was added. Produced.

[Production Example 13 of Two-Component Developer]
To the obtained “toner (1)”, a ferrite carrier (apparent density of 1.00 g / cm ³ ) is mixed so that the toner concentration becomes 6% by mass, and “two-component developer (13)” is added. Produced.

[Evaluation]
(1) Evaluation of image density, sleeve memory property, fog, and charge amount environment difference Image forming apparatus “bizhub PRO C6500” equipped with a developing device for two-component developer (print speed about 65 sheets / min) (Konica Minolta Business Technologies) “Two-component developers (1) to (20)” and “comparative two-component developers (1) to (5)” were respectively mounted. 300,000 prints were made using high-quality A4 size paper (65 g / m ² ) under ambient conditions of normal temperature and humidity (25 ° C., 50% RH), and the amount of toner adhered at the start and after the completion of 300,000 prints The image density of the solid image part of 4.0 g / m ² was measured and evaluated.
The image density was measured using a reflection densitometer “RD-918” (manufactured by Macbeth). The case where the image density after printing 300,000 sheets was 1.36 to 1.41 was determined to be acceptable.
Further, the image density of the solid image portion was measured at intervals of one round of the sleeve, and the difference in density was evaluated as the sleeve memory property. The case where the density difference was 0.00 to 0.05 was regarded as acceptable.
Further, the non-image portion of the A4 size high-quality paper was observed at a magnification of 100 using a microscope “VHX-2000” (manufactured by Keyence Corporation), and the average value of the area occupied by the toner in five fields of view was evaluated as fog. The occupation area ratio is calculated on the software by taking a photographed field of view using a commercially available image processing software, binarizing it. As a calculation formula, occupied area ratio (%) = (occupied area of toner) / (area of visual field). The case where the occupied area ratio was 0 to 0.5% was regarded as acceptable.
Further, after sampling the developer after endurance and leaving it overnight in a low temperature and low humidity environment (10 ° C., 15% RH) and a high temperature and high humidity environment (30 ° C., 80% RH), the blow-off charge measuring device “TB” -200 "(manufactured by Toshiba Chemical Co., Ltd.), and the difference between the two was evaluated as the difference in charge amount environment. The case where the difference was 7 μC / g or less was regarded as acceptable.
The results are shown in Table 3.

(2) Evaluation of cleaning property Using a modified machine of an image forming apparatus “bizhub PRO C6500” (printing speed of about 65 sheets / minute) (manufactured by Konica Minolta Business Technologies), “two-component developer (1) to (20) And “Comparative two-component developers (1) to (5)” were respectively mounted. In a low temperature and low humidity environment (10 ° C., 15% RH), the bias voltage was set so that the toner adhesion amount on the photosensitive member was 4 g / m ² , and the primary transfer current value was 0 μA. Thereafter, high-quality paper of A3 size (65 g / m ² ) was poured, the presence or absence of slipping of the image was visually confirmed, and the number of prints when slipping occurred was evaluated as the cleaning property. A case where the number of prints was 5 or more was regarded as acceptable.
The results are shown in Table 3.

Claims (5)

On the surface of the base particles containing a binder resin made of a styrene-acrylic copolymer, toner particles in which a plurality of bumps made of styrene-acrylic modified polyester resin are formed and an external additive ,
The average height of the bump is 50 to 120 nm,
The average diameter of the bump is 100 to 500 nm,
The average distribution density of the bumps in the base particles surface 2 to 15 / [mu] m are ^two der,
The electrostatic charge image , wherein the external additive includes hydrophobized silica fine particles having an average particle diameter of 20 to 40 nm, on the surface of which a reaction product derived from an alkylsilane having 6 to 16 carbon atoms is present. Development toner. 2. The electrostatic image developing toner according to claim 1, wherein an external additive composed of large-diameter silica fine particles having a particle diameter of 60 to 120 nm is further added to the toner particles. 3. The toner particle according to claim 2, further comprising an external additive comprising small-sized silica fine particles having a particle diameter of 5 to 20 nm or small-sized titania fine particles having a particle diameter of 5 to 20 nm. The toner for developing an electrostatic image according to the description.   The toner for developing an electrostatic charge image according to any one of claims 1 to 3, and an apparent density of 1.0 to 2.0 g / cm. ^Three A two-component developer comprising: a carrier that is   An image forming method using the two-component developer according to claim 4.