JP2021173839A - Toner and method for manufacturing the same, and developer including the same and image forming apparatus mounting the same - Google Patents

Abstract

To provide a toner that, even when both systems of a reverse developing system and a contact electrification roller system are employed, is excellent in filming resistance and can prevent image deterioration and form stable images for a long-term use, and a method for manufacturing the same, and developer including the same, and an image forming apparatus mounting the same.SOLUTION: A toner is formed of at least a toner base particle and an external additive externally added to the surface thereof. The external additive contains associated silica, and the toner base particle contains ester wax as a mold release agent. In differential scanning calorimetry (DSC), the temperature difference between an endothermic peak temperature and an exothermic peak temperature is 15 to 30°C.SELECTED DRAWING: None

Description

The present invention relates to a toner, a method for producing the same, a developer containing the toner, and an image forming apparatus equipped with the toner. More specifically, the present invention has excellent filming resistance, suppresses image deterioration over a long period of use, and forms a stable image even when both the reverse developing system and the contact charging roller system are adopted. The present invention relates to a possible toner, a method for producing the same, a developer containing the same, and an image forming apparatus equipped with the toner.

In recent years, with the remarkable development of office automation equipment, image forming devices such as copiers, printers, and facsimile machines using electrophotographic methods have become widespread.
In an image forming apparatus using an electrophotographic method, a charging step of uniformly charging the surface of a rotationally driven electrophotographic photosensitive member (also referred to as a “photoreceptor”) with a charging device; Exposure process of irradiating laser light to form an electrostatic latent image; The electrostatic latent image on the surface of the photoconductor is developed with an electrophotographic toner (also referred to as "toner") by a developing device to form a toner image. Development step; Transfer step of transferring the toner image on the surface of the photoconductor onto a recording paper (also referred to as "recording medium" or "transfer medium") by a transfer device; and fixing the toner image on the recording paper by heating the fixing device. An image is formed through the process.
Then, the transfer residual toner remaining on the surface of the photoconductor after the image forming operation is removed by the cleaning device in the cleaning step and collected in a predetermined recovery unit (development tank), and the residual charge on the surface of the photoconductor after cleaning is calculated. In order to prepare for the next image formation, the charge is removed by the static elimination device in the static elimination step.
Then, various methods of image formation have been proposed and put into practical use.

For example, the reverse development method widens the development nip width and secures high developability even with a small amount of developer, so it has merits such as ensuring developability in a low humidity environment, reducing cost, and making the developing tank compact. Since the nip width is strongly stressed, there is a demerit that the deterioration of the developer progresses quickly. Therefore, the durability of the toner is required, and in order to improve the durability, spherical silica particles having a large particle size having a high spacer effect are externally added. However, spherical silica particles having a large particle size are easily desorbed from the toner, and agglomerates of the external additive itself are present, which causes filming on a photoconductor drum (also referred to as “drum”).

In addition, the contact electrification roller method can secure a sufficient drum surface potential at a low voltage, so it has merits such as reduction of ozone generation, improvement of circuit design freedom by reducing high voltage substrate, and reduction of power consumption, but contact electrification. Therefore, the drum is easily scratched, and filming is likely to occur on the drum starting from the scratch. If unevenness is formed on the drum surface by filming, uneven charging occurs, which causes image defects. It has the disadvantage of being easily triggered. Therefore, it is effective not to use an external additive having a large particle size that is easily detached from the toner, and to bury it in the toner surface to prevent it from detaching even if it is used. However, with such a toner, a sufficient spacer effect cannot be obtained, and there remains a problem in durability and heat resistance of the toner.

Various techniques have been proposed to improve such toner problems.
For example, Japanese Patent Application Laid-Open No. 2012-088420 (Patent Document 1) describes monodisperse spherical silica having a volume average primary particle diameter of 60 nm or more and 100 nm or less and an average carbon content of 1.0% by mass or more and 3.0% by mass or less. A toner for electrostatic latent image development, which is used in an image forming method by a reverse development method, has been proposed.
Further, Japanese Patent Application Laid-Open No. 2014-186050 (Patent Document 2) describes an electrostatic charge image developer toner having toner particles and an external additive containing titanium acid compound particles having an iron content of more than 1200 ppm and 6000 ppm or less. Has been proposed.
On the other hand, a method for producing associative silica fine particles in which two or more primary particles having an average particle size in the range of 5 to 500 nm are associated, and a static charge image developer toner external additive composed of the hydrophobic associative silica fine particles produced thereby. Has been proposed.

Japanese Unexamined Patent Publication No. 2012-08420 Japanese Unexamined Patent Publication No. 2014-186050 Japanese Unexamined Patent Publication No. 2012-025596

As described above, although the reverse development method and the contact charging roller method have many merits, they are required to have contradictory characteristics as toner. Therefore, in the case of an image forming apparatus using both systems, they are matched with the system. It was very difficult to establish a toner formulation.
Patent Document 3 proposes a method for producing associative silica fine particles corresponding to the associative silica of the present invention, and a static charge image developer toner external additive composed of the hydrophobic associative silica fine particles produced thereby. , Combination with a specific release agent as described later, and further, small particle size silica and its combination are not disclosed.

Therefore, the present invention is excellent in filming resistance, suppresses image deterioration over a long period of use, and can form a stable image even when both the reverse development method and the contact charging roller method are adopted. An object of the present invention is to provide a toner, a method for producing the same, a developer containing the toner, and an image forming apparatus equipped with the toner.

As a result of diligent studies to solve the above problems, the present inventors are composed of an external additive containing associative silica and toner matrix particles containing a specific mold release agent and having specific thermal characteristics. It has been found that the toner produced is excellent in filming resistance, can suppress image deterioration over a long period of use, and can form a stable image, and has completed the present invention.

Thus, according to the present invention, it is composed of at least the toner matrix particles and the external additive added to the surface thereof.
The external additive contains associative silica, and the toner mother particles contain an ester wax as a release agent.
Provided is a toner characterized in that the temperature difference between the endothermic peak temperature and the exothermic peak temperature is 15 to 30 ° C. in differential scanning calorimetry (DSC).

Further, according to the present invention, it is the above-mentioned method for producing toner.
The first external addition step of adding and mixing the small particle size silica as the first external particle component to the toner mother particles and externally adding the small particle size silica to the toner mother particles, and the obtained toner mother. A method for producing a toner, which comprises a second externaling step of adding and mixing the associated silica as a second external additive component to the particles and externally adding the associated silica to the toner mother particles. Is provided.

Further, according to the present invention, there is provided a developer characterized by containing the above-mentioned toner and a carrier.

Further, according to the present invention, there is provided an image forming apparatus equipped with the above-mentioned toner and a charging roller system as a method for charging the surface of a photoconductor.

According to the present invention, even when both the reverse developing system and the contact charging roller system are adopted, it is possible to have excellent filming resistance, suppress image deterioration over a long period of use, and form a stable image. It is possible to provide a toner, a method for producing the same, a developer containing the toner, and an image forming apparatus equipped with the toner.

The toner of the present invention more exerts the above-mentioned effect when at least one of the following conditions (1) to (5) is satisfied.
(1) The associative silica has an average secondary particle size of 100 to 300 nm and an association degree of 2.0 to 3.0.
(2) The ester wax is contained in the toner matrix particles in a proportion of 0.5 to 5.0% by mass.
(3) The external additive further contains small particle size silica having an average primary particle size of 15 nm or less.
(4) The associative silica and the small particle size silica are contained in the proportions of 0.2 to 2.0% by mass and 0.2 to 1.5% by mass, respectively, with respect to the toner mother particles.
(5) The toner has a peak top molecular weight (Mp) of 4000 to 6500 in gel permeation chromatography (GPC) measurements.

It is a schematic side view which shows the structure of the main part of the example of the image forming apparatus of this invention. It is a schematic side view which shows the structure of the main part of the charging member of the charging means in the image forming apparatus of this invention.

(1) Toner The toner of the present invention is composed of at least toner matrix particles and an external additive added to the surface thereof.
The external additive contains associative silica, and the toner mother particles contain an ester wax as a release agent.
In differential scanning calorimetry (DSC), the temperature difference between the endothermic peak temperature and the exothermic peak temperature is 15 to 30 ° C.
Hereinafter, the external additive and the mold release agent of the characteristic portion of the toner of the present invention will be described, and an image equipped with a toner mother particle, a toner manufacturing method, a developer containing the toner, and a toner and a charging roller system, which are the basics of the toner. The forming apparatus will be described.

(1-1) External Additive The external additive generally has a function of improving the transportability and chargeability of the toner, and the agitation property with a carrier when the toner is used as a two-component developer.
The toner of the present invention contains associative silica as an external additive, or preferably contains associative silica with a smaller particle size silica.

(1-1-1) Associative Silica The "associative type" of the associative silica used in the present invention is a normal form in which primary particles are aggregated to form a sphere and primary particles are aggregated to form an agglomerate. It means particles in which two or more primary particles are associated to form a chain, fibrous, or other irregularly shaped particles.
As the embodiment, two primary particles are associated, three or more are associated in a chain, three are associated at three points, and four are associated in a plane or in a tetrapod shape. Examples include those in which five or more particles are associated with each other, and those in which these associated silica groups are bonded to each other.
Here, the "primary particle" means a particle that is the smallest unit of particles forming a powder.

The associative silica particles have a larger contact (adhesion) area with the surface of the toner mother particles than the silica particles in the normal form, so that they are difficult to separate from the toner surface. Further, since the associative silica particles have an indefinite shape, aggregates are unlikely to be generated, so that the occurrence of filming can be suppressed while ensuring a sufficient spacer effect.
The shape of the primary particles constituting the associative silica may be spherical, egg-shaped, dice-shaped, or rod-shaped, but spherical shape is preferable for external additive applications. Further, the particle sizes of the primary particles may be different from each other.

The associative silica preferably has an average secondary particle size of 100 to 300 nm and an association degree of 2.0 to 3.0.
By using associative silica with an average secondary particle size of 100 nm or more, a sufficient spacer effect can be exhibited, and a stable image can be provided by suppressing the seizure phenomenon on the surface of the developing roller over a long period of use. can.
If the average secondary particle size of the associative silica is less than 100 nm, a sufficient spacer effect may not be obtained. On the other hand, when the average secondary particle size of the associative silica exceeds 300 nm, even if the degree of association is a specified value, it is likely to be detached from the toner surface, and the filming resistance may be deteriorated.
The average secondary particle size of the more preferable associative silica is 120 to 200 nm.

The degree of association indicates the shape of the toner, and the larger the value, the more irregular the shape.
The degree of association of the associative silica can be obtained from the average primary particle diameter d1 and the average secondary particle diameter d2 of the silica particles by the formula: d2 / d1.
Particles with an association degree of less than 1.7 are also called spherical, particles with an association degree of 1.7 or more and less than 2.2 are called eyebrows, and particles with an association degree of 2.2 or more are also called association type.

The average primary particle size of the silica particles can be measured as follows.
The average primary particle size of the silica particles is converted from the specific surface area measurement value by the BET method.
In the toner of the present invention, the average primary particle size of the silica particles constituting the associative silica is about 40 to 70 nm.

The average secondary particle size of the silica particles can be measured as follows.
The average secondary particle size of the silica particles can be arbitrarily determined from the obtained image obtained by photographing the particles with a scanning electron microscope (SEM) (for example, manufactured by Hitachi High-Technologies Co., Ltd., model: S-4800). The particle size (major axis) of 100 silica fine particles on the surface of the toner is measured, the average value of the 100 particle sizes is calculated, and this is used as the average secondary particle size.

By using associative silica having an association degree of 2.0 or more, the contact area with the toner matrix particles is increased, desorption from the toner surface is prevented, and the generation of aggregates is suppressed to improve the filming resistance. be able to.
If the degree of association of the associative silica is less than 2.0, the above effects may not be obtained. On the other hand, when the degree of association of the associative silica exceeds 3.0, the particles become too deformed, the contact area with the toner surface cannot be increased, the particles are easily detached from the toner surface, and the filming resistance deteriorates. Sometimes.
The more preferable degree of association of the associative silica is 2.2 to 2.7.

The associative silica can be produced by the method described in JP2012-025596, and a commercially available product as used in Examples can also be used.

(1-1-2) Small Particle Size Silica The external additive preferably further contains small particle size silica having an average primary particle size of 15 nm or less.
By further containing the small particle size silica in the external additive, the fluidity of the toner mother particles can be appropriately improved, the generation of aggregates of the associated silica can be further suppressed, and the external additive can be adhered to the toner surface. can.
If the average primary particle size of the small particle size silica exceeds 15 nm, the above effects may not be obtained. The upper limit of the average primary particle size of the preferred small particle size silica is 12 nm, and the lower limit thereof is about 5 nm.
As the small particle size silica, a commercially available product as used in the examples can be used.

(1-1-3) Content of external additive When the external additive is associative silica alone, the content thereof is preferably 1.0 to 4.0% by mass with respect to the toner matrix particles.
The associative silica contributes to a moderate spacer effect.
If the content of the associative silica is less than 1.0% by mass with respect to the toner matrix particles, a sufficient spacer effect may not be exhibited. On the other hand, if the content of the associative silica exceeds 4.0% by mass with respect to the toner matrix particles, the amount of liberated silica may increase and the filming resistance may deteriorate.
A more preferable content of associative silica is 1.5 to 3.0% by mass with respect to the toner matrix particles.

When the external additive is a combination of associative silica and small particle size silica, their contents are 0.2 to 2.0% by mass and 0.2 to 1.5% by mass, respectively, with respect to the toner mother particles. It is preferable that the ratio is.
The associative silica contributes to an appropriate spacer effect, and the small particle size silica contributes to the improvement of fluidity.
If the content of the associative silica is less than 0.2% by mass with respect to the toner matrix particles, a sufficient spacer effect may not be exhibited. On the other hand, if the content of the associative silica exceeds 1.5% by mass with respect to the toner matrix particles, the amount of liberated silica may increase and the filming resistance may deteriorate.
If the content of the small particle size silica is less than 0.2% by mass with respect to the toner mother particles, sufficient fluidity may not be ensured. On the other hand, when the content of the small particle size silica exceeds 1.5% by mass with respect to the toner mother particles, the small particle size silica covers the toner surface too much, and conversely prevents the associative silica from adhering to the toner surface. As a result, the release of associative silica may be increased and the filming resistance may be deteriorated.
The contents of the more preferable associative silica and small particle size silica are 0.5 to 1.5% by mass and 0.5 to 1.3% by mass, respectively, with respect to the toner mother particles.

(1-2) Release Agent The release agent is added to the toner matrix particles in order to impart mold releasability to the toner when the toner is fixed on the recording medium. In the toner of the present invention, the release agent is dispersed in the binder resin.
The release agent contained in the toner of the present invention is an ester wax.
The ester wax has a high polarity, is easily compatible with a binder resin described later, particularly an amorphous polyester resin, is structurally stable, and can give preferable thermal properties to the toner matrix particles.
Examples of the ester wax include Nissan Elector wax (manufactured by NOF CORPORATION, product names: WEP-5, WEP-14, WEP-15) as used in the examples.
On the other hand, hydrocarbon-based waxes are poorly dispersed in a binder resin such as polyester resin, and in long-term use, a seizure phenomenon or the like on a developing roller is likely to occur, which causes image defects.

The ester wax preferably has a transparent melting point of 65 to 85 ° C.
By using such an ester wax, it is possible to give preferable thermal properties to the toner matrix particles.

The ester wax is preferably contained in the toner matrix particles in a proportion of 0.5 to 5.0% by mass.
If the ester wax content is less than 0.5%, the above effect may not be sufficiently obtained. On the other hand, when the content of the ester wax exceeds 5.0 parts by weight, the dispersion of the wax deteriorates, the exposure of the wax to the toner surface and the release from the toner matrix particles increase, and the wax is applied to the developing roller in a long-term use. A seizure phenomenon or the like is likely to occur, which not only causes image defects but also deteriorates heat-resistant storage characteristics.
The preferable ester wax content is 2.0 to 3.5% by mass.

(1-3) Toner Mother Particle The toner mother particle constituting the toner of the present invention contains at least a binder resin, a colorant, a mold release agent and a charge control agent, and is necessary as long as the effect of the present invention is not impaired. Depending on the situation, known additives may be included.

(1-3-1) Bending Resin As the binding resin contained in the toner matrix particles of the present invention, a polyester resin can be preferably used.
The polyester resin is usually one or more selected from a divalent alcohol component and a trihydric or higher polyhydric alcohol component, and one or more selected from a divalent carboxylic acid and a trivalent or higher polyvalent carboxylic acid. Is obtained by polycondensation reaction, esterification, or transesterification reaction by a known method.
The conditions for the polycondensation reaction may be appropriately set depending on the reactivity of the monomer component, and the reaction may be terminated when the polymer has suitable physical characteristics. For example, the reaction temperature is about 170 to 250 ° C., and the reaction pressure is about 5 mmHg to normal pressure.

Examples of the divalent alcohol component include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxypropylene (3.3) -2,2-bis (4-hydroxy). Phenyl) Propylene, Polyoxypropylene (2.0) -2,2-Bis (4-Hydroxyphenyl) Propylene, Polyoxypropylene (2.0) -Polyoxyethylene (2.0) -2,2-Bis ( Alkylene oxide adducts of bisphenol A such as 4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane; ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene Glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, di Diores such as propylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A; propylene adduct of bisphenol A; ethylene adduct of bisphenol A; hydrogenated bisphenol A and the like.

Examples of the trihydric or higher polyhydric alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sculose (sugar), and 1 , 2,4-Butantriol, 1,2,5-pentantriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butantriol, trimethylolethane, trimethylolpropane, 1,3 Examples thereof include 5-trihydroxymethylbenzene.
In the toner of the present invention, one of the above-mentioned divalent alcohol component and trivalent or higher-valent polyhydric alcohol component can be used alone or in combination of two or more.

Divalent carboxylic acids include, for example, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebatic acid, azelaic acid, malon. Examples thereof include acids, n-dodecenyl succinic acid, n-dodecyl succinic acid, n-octyl succinic acid, isooctenyl succinic acid, isooctyl succinic acid and acid anhydrides or lower alkyl esters thereof.

Examples of the trivalent or higher polyvalent carboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, and 1,2,4-naphthalene. Tricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, Examples thereof include tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimeric acid and acid anhydrides or lower alkyl esters thereof.
In the toner of the present invention, one of the above divalent carboxylic acid and trivalent or higher polyvalent carboxylic acid can be used alone or in combination of two or more.

In the toner of the present invention, the binder resin preferably has a mass average molecular weight in the range of 9,000 to 90,000, and the ratio of the molecular weight of 100,000 or more in the molecular weight distribution is 10 to 30%. When the mass average molecular weight and the ratio of the molecular weight of 100,000 or more of the binder resin are within the above ranges, the effect of achieving both low temperature fixability and hot offset resistance in the belt fixing device is further exhibited.
If the mass average molecular weight of the binder resin is less than 9,000, the peelability on the fixing high temperature side may be deteriorated, while if the mass average molecular weight of the binder resin exceeds 90,000, the low temperature fixability is poor. There is a risk of becoming.
By setting the mass average molecular weight of the binder resin to 20,000 or more, the peelability on the fixing high temperature side can be further improved, while the mass average molecular weight of the binder resin is 70,000 or less. By doing so, the low temperature fixability can be further reliably improved.
Therefore, the more preferable range of the mass average molecular weight of the binder resin is 20,000 to 70,000.

Further, if the ratio of the molecular weight of the binder resin to the molecular weight distribution of 100,000 or more is less than 10%, the peelability on the fixing high temperature side may be deteriorated. On the other hand, if the proportion of the molecular weight distribution of the binder resin having a molecular weight of 100,000 or more exceeds 30%, the low temperature fixability may deteriorate. By setting this ratio to 20% or less, the low temperature fixability can be further reliably improved.
Therefore, the range of the ratio of the molecular weight of 100,000 or more in the more preferable molecular weight distribution of the binder resin is 10 to 20%.

The content of the binder resin in the toner mother particles is preferably 60 to 90% by mass, and particularly preferably 70 to 85% by mass.

(1-3-2) Colorant As the colorant contained in the toner matrix particles of the present invention, various types and colors of organic and inorganic pigments and dyes commonly used in the art can be used. For example, black, white, yellow, orange, red, purple, blue and green colorants.

Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, non-magnetic ferrite, magnetic ferrite and magnetite.
Examples of the white colorant include zinc white, titanium oxide, antimony white, zinc sulfide and the like.

Examples of the yellow colorant include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, nable yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, and benzidine. Yellow GR, Kinolin Yellow Lake, Permanent Yellow NCG, Tartrajin Lake, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 138 and the like.

Examples of the orange colorant include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indus lem brilliant orange RK, benzidine orange G, indus lem brilliant orange GK, and C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43 and the like.

Examples of red colorants include red iron oxide, cadmium red, lead tan, mercury sulfide, cadmium, permanent red 4R, resole red, pyrazolone red, watching red, calcium salt, lake red C, lake red D, and brilliant carmine 6B. , Eosin Lake, Rhodamin Lake B, Alizarin Lake, Brilliant Carmin 3B, C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 222 and the like.

Examples of the purple colorant include manganese purple, fast violet B, and methyl violet lake.
Examples of blue colorants include dark blue, cobalt blue, alkaline blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, induslen blue BC, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60 and the like.
Examples of the green colorant include chrome green, chromium oxide, picment green B, mica light green lake, final yellow green G, and C.I. I. Pigment Green 7 and the like.

In the toner of the present invention, one of the above colorants may be used alone or in combination of two, and the combination thereof may be a different color or the same color.
Further, two or more kinds of colorants may be used as composite particles. The composite particles can be produced, for example, by adding an appropriate amount of water, lower alcohol, or the like to two or more kinds of colorants, granulating them with a general granulator such as a high speed mill, and drying them. Further, in order to uniformly disperse the colorant in the binder resin, it may be used as a masterbatch. The composite particles and masterbatch are mixed into the toner composition during dry mixing.

The content of the colorant in the toner mother particles of the present invention is not particularly limited, but is preferably 0.1 to 20 parts by mass, and more preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the binder resin. It is a mass part.
When the content of the colorant is within the above range, it is possible to form an image having a high image density and very good image quality without impairing various physical characteristics of the toner.
In terms of conversion, the content of the colorant in the toner matrix particles is preferably 2.5 to 7.5% by mass, and more preferably 3.0 to 6.5% by mass.

(1-3-3) Release Agent The release agent contained in the toner of the present invention is the above-mentioned ester wax.

(1-3-4) Charge Control Agent As the charge control agent contained in the toner of the present invention, a charge control agent for negative charge control commonly used in the art can be used.
Examples of the charge control agent for negative charge control include oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, naphthenic acid metal salts, metal complexes and metal salts of salicylic acid and its derivatives ( Metals include chromium, zinc, zirconium, etc.), boron compounds, fatty acid soaps, long-chain alkylcarboxylates, resin acid soaps, and the like.
In the toner of the present invention, one of the above charge control agents can be used alone or in combination of two or more.

The content of the charge control agent in the toner mother particles of the present invention is not particularly limited, but is preferably 0.5 to 3 parts by mass, and more preferably 1 to 2 parts by mass with respect to 100 parts by mass of the binder resin. It is a department.
When the content of the charge control agent is within the above range, it is possible to form an image having a high image density and very good image quality without impairing various physical characteristics of the toner.
In terms of conversion, the content of the charge control agent in the toner mother particles is preferably 0.5 to 2.0% by mass, and more preferably 0.7 to 1.5% by mass.

(1-3-5) Physical properties of toner (temperature difference between endothermic peak temperature and exothermic peak temperature in differential scanning calorimetry (DSC))
The toner of the present invention has a temperature difference of 15 to 30 ° C. between the heat absorption peak temperature and the heat generation peak temperature in differential scanning calorimetry (DSC), that is, the "heat absorption peak temperature T1" when the DSC is raised (heated). The "temperature difference ΔT" of the "heat generation peak temperature T2" at the time of lowering the temperature (cooling) is 15 ° C. to 30 ° C.
This measuring method will be described in detail in Examples.

This thermal property is particularly affected by the release agent among the constituent materials of the toner matrix particles. When the binder resin of the toner mother particles, which is a preferred embodiment of the toner of the present invention, is a polyester resin, the release agent is preferably an ester wax.
When a specific polyester resin is used as the binder resin, the above thermal properties can be adjusted by appropriately selecting an ester wax as a release agent.
The fact that the temperature difference ΔT is in the above range suggests that the ester-based wax has a high plasticizing effect on the binder resin, which further improves the adhesive force between the external additive and the toner matrix particles. The resistance to drum filming can be further improved.

If the temperature difference ΔT is less than 15 ° C., the above effects are difficult to obtain, and even if associative silica is used, sufficient filming resistance is sufficient in an image forming apparatus equipped with a charging roller system having low filming resistance. May not be obtained. On the other hand, if the temperature difference ΔT exceeds 30 ° C., it is difficult to produce an ester wax and it is difficult to confirm it, but if the plasticizing effect is too high, it is assumed that the heat-resistant storage characteristics deteriorate.
The preferred temperature difference is 18-25 ° C.

(Peak top molecular weight of toner: Mp)
The toner of the present invention preferably has a peak top molecular weight (Mp) of 4000 to 6500 in gel permeation chromatography (GPC) measurements.
This measuring method will be described in detail in Examples.
By setting the peak top molecular weight to a low molecular weight, the surface of the toner matrix particles becomes relatively soft, and the adhesive force between the external additive and silica can be further improved.
If the peak top molecular weight of the toner is less than 4000, the heat-resistant storage characteristics and durability may deteriorate. On the other hand, if the peak top molecular weight of the toner exceeds 6500, the above effects may not be obtained.
A more preferable peak top molecular weight of the toner is 5000 to 6000.

(Average primary particle size of toner)
The toner of the present invention preferably has an average primary particle size of 4 to 10 μm.
If the average primary particle size is less than 4 μm, the particle size of the toner mother particles becomes too small, which may lead to high charging and deterioration of fluidity. When the charge becomes high and the fluidity deteriorates, the toner cannot be stably supplied to the photoconductor, and there is a possibility that the background fog and the decrease in image density may occur. On the other hand, if the average primary particle size exceeds 10 μm, the particle size of the toner mother particles is large, the layer thickness of the formed image becomes high, and the image becomes remarkably grainy, which is not desirable because a high-definition image cannot be obtained. Further, as the particle size of the toner mother particles increases, the specific surface area decreases and the amount of charge of the toner decreases. If the amount of charge of the toner becomes small, the toner is not stably supplied to the photoconductor, and there is a possibility that the inside of the machine is contaminated due to the scattering of the toner. The preferred average primary particle size is 5-8 μm.

(2) Toner Manufacturing Method The toner manufacturing method of the present invention is as follows.
In the first externaling step of adding and mixing small particle size silica as the first external particle component to the toner mother particles and externally adding the small particle size silica to the toner mother particles, and to the obtained toner mother particles. It is characterized by including a second externaling step of adding and mixing associative silica as a second externalizing agent component and externally adding the associative silica to the toner mother particles.
When the external additive is a combination of associative silica and small particle size silica, in the external addition step, the small particle size silica is externally added in the first external addition step as described above, and then the large particle size silica is added in the second external addition step. It is preferable to externally add associative silica having a particle size. By externally adding in this order, the effect of improving the fluidity of the small particle size silica can be obtained.

(2-1) First External Addition Step In the first external addition step, an external additive of small particle size silica is added to the toner matrix particles and mixed.
The operation of addition / mixing can be carried out using a known device commonly used in the art, and the conditions in the process may be appropriately set according to the target material and desired physical characteristics.

(2-2) Second External Addition Step In the second external addition step, an external additive of associative silica is further added to the obtained toner matrix particles and mixed.
Similar to the first external addition step, the addition / mixing operation can be carried out using a known device commonly used in the art, and the conditions in the step are appropriately determined depending on the target material and desired physical characteristics. You can set it.

(2-3) Method for Producing Toner Mother Particle The toner mother particle used in the present invention is prepared by a known method using a known device commonly used in the art, for example, at least a binder resin, a colorant and a mold release. The mixing step of mixing the coarsely pulverized melt-kneaded product containing the agent and the filler, the pulverizing step of pulverizing the mixture obtained in the mixing step, and the pulverized product obtained in the pulverizing step are classified. It can be produced by a classification step of spheroidizing and a spheroidizing treatment step of spheroidizing the classified product obtained in the classification step with hot air.
The dry method is preferable because the number of steps is smaller than that of the wet method and the equipment cost is not required, and the pulverization method is particularly preferable.
The conditions in each of the following steps may be appropriately set according to the target material and desired physical properties.

(3) Developer (two-component developer)
The developer of the present invention is characterized by containing the toner of the present invention and a carrier.
(Career)
The toner of the present invention can be used in any form of a one-component developer and a two-component developer, and when used as a two-component developer, it further contains a carrier in addition to the external additive.
As the carrier, a carrier commonly used in the art can be used. For example, single or composite ferrite and carrier core particles composed of iron, copper, zinc, nickel, cobalt, manganese, chromium and the like can be used as a known coating material. Examples include those with a surface coating.
The average particle size of the carriers is preferably 10 to 100 μm, more preferably 20 to 50 μm.
The content of the carrier is not particularly limited, but is preferably 85 to 97% by mass, more preferably 90 to 95% by mass, based on the total amount of the developing agent.

(4) Image Forming Device The image forming device of the present invention is equipped with the toner of the present invention and a charging roller system as a method of charging the surface of the photoconductor.
FIG. 1 is a schematic side view showing the configuration of a main part of an example of the image forming apparatus of the present invention.
The image forming apparatus 700 of FIG. 1 is a monochrome printer (laser printer), and exposes the photoconductor F, the charging means (charger) 710 for charging the surface Fa of the photoconductor F, and the charged photoconductor F. An exposure means (exposure apparatus) 720 that forms an electrostatic latent image, a developing means (developer) 730 that develops an electrostatic latent image formed by exposure to form a toner image, and a developing means (developer) formed by development. A transfer means (transfer charger) 740 that transfers a toner image onto a recording medium P such as a recording paper, a transport belt (not shown), and a transferred toner image are fixed on the recording medium P to form an image. The fixing means (fixing device) 760 and the cleaning means (cleaner device) 750 for removing and recovering the toner remaining on the photoconductor F are provided.

The image forming apparatus 700 is a monochrome printer, but may be, for example, an intermediate transfer type color image forming apparatus capable of forming a color image. Specifically, it may be a so-called tandem full-color image forming apparatus in which a plurality of photoconductors on which toner images are formed are arranged side by side in a predetermined direction (for example, horizontal direction H or vertical direction V). Further, the image forming apparatus 100 may be another color image forming apparatus, a copying machine, a multifunction device, or a facsimile apparatus.

The photoconductor F is rotatably supported by the main body of the image forming apparatus 700 (not shown), and is rotationally driven in the arrow R direction around the rotation axis α1 by a driving means (not shown). The driving means includes, for example, an electric motor and a reduction gear, and by transmitting the driving force to the substrate (also referred to as “conductive support”) F1 constituting the core body of the photoconductor F, the photoconductor F Is rotationally driven at a predetermined peripheral speed. The charging means (charger) 710, the exposure means 720, the developing means (developer) 730, the transfer means (transfer charger) 740 and the cleaning means (cleaner) 750 are arranged in this order along the outer peripheral surface of the photoconductor F. , The photoconductor F indicated by the arrow R is provided from the upstream side to the downstream side in the rotation direction. Each component constituting these image forming apparatus 700 is housed in a housing 780.

(4-1) Electrophotographic photosensitive member: F
The photoconductor is a laminated electrophotographic photosensitive member having at least a laminated photosensitive layer in which a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance are laminated in this order on a substrate. A laminated photoconductor) or a single-layer electrophotographic photosensitive member (single-layer photosensitive member) having at least a single-layer photosensitive layer containing a charge generating substance and a charge transporting substance can be used.

(4-2) Charging means: 710
The charging means (charger) 710 is a device that uniformly charges the outer peripheral surface Fa of the photoconductor F to a predetermined potential. As the charger 710, for example, a contact charger having a roller shape, a belt shape, a blade shape, or the like can be used.
It is optimal that the voltage is applied to the charging member such as the charging roller only by the DC voltage from the viewpoint of the cost of the power supply (high voltage applying device) 711, the life of the photoconductor Fa and the charging member, and the like.

Here, an example in which a roller-shaped contact charger is used as the charger 710 will be described.
FIG. 2 is a schematic side view showing a configuration of a main part of a charging member of a charging means in the image forming apparatus of the present invention, and a charging roller G, which is at least a part of the charging device 710, uses a conductive support G1 as a substrate. As a coating layer, an elastic layer G2 and a resistance layer G3 are formed on the outer peripheral surface in this order.

(4-2-1) Conductive support: G1
The conductive support is not particularly limited as long as it has conductivity and can maintain the strength as a charging member, and is, for example, at least one metal material selected from iron, copper, stainless steel, aluminum and nickel. A round bar made of. Further, the surface of the conductive support G1 may be plated in order to prevent rust and impart scratch resistance as long as the conductivity is not impaired.

(4-2-2) Elastic layer: G2
The elastic layer has appropriate conductivity and elasticity in order to supply power to the photoconductor as a charged body and to ensure good uniform adhesion of the charging roller to the photoconductor F.
In order to ensure uniform adhesion between the charging roller and the photoconductor, the elastic layer has a shape in which the elastic layer is polished so that the central portion is the thickest and the elastic layer becomes thinner from the central portion to both ends (so-called). Crown shape) is preferable.
Generally, the charging roller is brought into contact with the photoconductor by applying a predetermined pressing force to both ends of the conductive support. Therefore, the pressing force is small at the central portion and large at both ends. Therefore, there is no problem when the straightness of the charging roller is sufficient, but there is a problem that density unevenness occurs in the images corresponding to the central portion and both end portions when the straightness is not sufficient. In addition, since the charging area is expanding due to the increase in A3 Nobi compatible models and the number of color machines, the charging roller itself is easily bent by the pressing force only on both ends of the conductive support, and there is a gap in the center. There is a problem that it can be done. For this reason, it is preferable that the elastic layer G2 has a crown shape.

The elastic layer is a conductive agent having an electron conduction mechanism such as carbon black, graphite, or a conductive metal oxide in an elastic material such as rubber, and a conductive agent having an ion conduction mechanism such as an alkali metal salt or a quaternary ammonium salt. Can be appropriately added and formed by a known method. Its volume resistance is preferably adjusted to exhibit conductivity of less than ^{1 × 10 10 Ωcm.}
Examples of the elastic material include natural rubber, ethylene propylene rubber (EPDM), styrene butadiene rubber (SBR), silicone rubber, urethane rubber, epichlorohydrin rubber, isoprene rubber (IR), butadiene rubber (BR), and nitrile butadiene rubber (NBR). ) And synthetic rubber such as chloroprene rubber (CR), and examples thereof include polyamide resin, polyurethane resin, and silicone resin.

The film thickness of the elastic layer is not particularly limited, but is preferably 1 to 3 mm, more preferably 1.5 to 2 mm.

(4-2-3) Resistance layer: G3
The resistance layer is formed in contact with the elastic layer to prevent bleeding out of softening oil, plasticizer, etc. contained in the elastic layer to the surface of the charging roller, and is provided to adjust the electrical resistance of the entire charging roller. Be done.
Examples of the material forming the resistance layer include epichlorohydrin rubber, nitrile butadiene rubber (NBR), polyolefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, fluororubber-based thermoplastic elastomer, and polyester-based thermoplastic. Examples thereof include elastomers, polyamide-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, ethylene vinyl acetate-based thermoplastic elastomers, polyvinyl chloride-based thermoplastic elastomers, chlorinated polyethylene-based thermoplastic elastomers, and one of these alone or Two or more kinds can be used as a mixture or a copolymer.

The resistance layer is conductive or semi-conductive. Therefore, the above-mentioned material includes a conductive agent having an electron conduction mechanism (for example, conductive carbon, graphite, conductive metal oxide, copper, aluminum, nickel, iron powder, etc.) or a conductive agent having an ion conduction mechanism (for example, conductive carbon, aluminum, nickel, iron powder, etc.). For example, it is formed by appropriately adding an alkali metal salt, an aluminum salt, etc.).
In this case, two or more kinds of various conductive agents may be used in combination in order to obtain a desired electric resistance. However, considering environmental changes and contamination of the photoconductor, it is preferable to use a conductive agent having an electron conduction mechanism.

The charging means of the image forming apparatus of the present invention includes a charging member having a surface roughness of 5.0 to 13 μm.
Indicators indicating surface roughness include, for example, ten-point average surface roughness (Rz), arithmetic average roughness (Ra), maximum roughness (Ry), average spacing of irregularities (Sm), and the like. In the above, "surface roughness" means ten-point average surface roughness (Rz) unless otherwise specified.

The surface of the charging roller is usually formed with irregularities, but by setting the surface roughness of the charging roller within the above range, a stable charging potential can always be ensured, and there is no problem with toner cleaning performance. This makes it possible to always obtain a good image. In particular, when only a DC voltage is applied to the charging roller, the convex portion (projection) on the surface of the charging roller becomes an appropriate discharge point, and a stable charging potential can always be secured. That is, by forming the convex portion and the concave portion on the surface of the charging roller, the convex portion charges the photoconductor F.
If the surface roughness of the charging member is less than 5.0 μm, it may not be possible to suppress streak-like charging unevenness on the halftone image. On the other hand, if the surface roughness of the charging member exceeds 13 μm, streak-like charging unevenness on the halftone image can be suppressed, but image fog may worsen.
The surface roughness of the preferred charging member is 7.0 to 11.0 μm.

The surface roughness can be adjusted by changing the polishing conditions of the surface layer (resistance layer) of the charging roller. Further, in order to further stabilize the charging, a filler may be contained in the surface layer (resistance layer) of the charging roller. In this case, it is desirable to improve the dispersed state of the protrusions on the surface of the charging roller by changing the type and particle size of the filler.

The filler is not particularly limited as long as the effect of the invention is not significantly impaired.
Fillers include, for example, calcium carbonate, talc, mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, zinc oxide, zeolite, wolastonite, silica soil, glass beads, bentonite, montmorillonite, asbestos, etc. Hollow glass bulb, graphite, molybdenum disulfide, titanium oxide, aluminum fiber, stainless steel fiber, brass fiber, aluminum powder, wood flour, rice husk, graphite, metal powder, conductive metal oxide, organic metal compound, organic metal salt Etc., and one of these can be used alone or in combination of two or more trees.
The film thickness of the resistance layer is not particularly limited, but is preferably 5 to 100 μm, and more preferably 5 to 20 μm.

(4-3) Exposure means: 720
The exposure means is a device that emits light modulated based on image information. In FIG. 1, a semiconductor laser or a light emitting diode is provided as a light source, and the laser beam light output from the light source is applied to the surface (outer peripheral surface) Fa of the photoconductor F between the charger 710 and the developing device 730. , The surface Fa of the charged photoconductor F is exposed according to the image information. The light is repeatedly scanned in the direction in which the rotation axis α1 of the photoconductor F extends, which is the main scanning direction, and these are imaged to sequentially form an electrostatic latent image on the surface Fa of the photoconductor F. That is, the charged amount of the photoconductor F uniformly charged by the charger 710 differs depending on whether the laser beam is irradiated or not, and an electrostatic latent image is formed.

(4-4) Developing means: 730
The developing means (developer) 730 is a device for developing an electrostatic latent image formed on the surface Fa of the photoconductor F by exposure with a developer (toner) D, and is provided so as to face the photoconductor F. The developing roller 730a that supplies toner to the surface Fa of the photoconductor F and the developing roller 730a are rotatably supported around the rotating axis α2 that is parallel to or substantially parallel to the rotating axis α1 of the photoconductor 1, and the toner is supplied to the internal space thereof. It is provided with a casing 730b for accommodating the developer to be contained.

(4-5) Transfer means: 740
The transfer means (transfer charger) 740 transfers a toner image, which is a visible image formed on the surface Fa of the photoconductor F by development, from a predetermined transport direction (arrow W direction) by a transport means (not shown). This is a device for transferring onto transfer paper P, which is a recording medium supplied between the transfer charger 740 and the transfer charger 740. The transfer means applies a predetermined high voltage to the transfer nip portion TN formed between the photoconductor F and the transfer charger 740 by the high voltage application device 741. The transfer means can be configured in the same manner as the above-mentioned charging means, and is, for example, a contact-type transfer means that transfers a toner image onto the recording medium P by applying a charge having a polarity opposite to that of the toner D to the recording medium P. be.

(4-6) Fixing means: 760
The fixing means (fixing device) 760 is a device for fixing the toner image transferred to the recording medium P by the transfer means 740 to the recording medium P. The fixing device 760 is provided on the downstream side of the transfer nip portion TN between the photoconductor F and the transfer charging device 740 in the transport direction W. For example, the fixing device 760 is provided on the heating roller 760a and facing the heating roller 760a. The pressure roller 760b is pressed by the heating roller 760a to form a fixing nip portion FN.

(4-7) Cleaning means: 750
The cleaning means (cleaner) 750 is a cleaning device that removes and recovers the toner remaining on the surface Fa of the photoconductor F after the transfer operation by the transfer means 760. The cleaner 750 includes a cleaning blade 750a for peeling the toner D remaining on the surface Fa of the photoconductor F, and a recovery casing 750b for accommodating the toner D peeled by the cleaning blade 750a.

(4-8) Static Eliminating Means: Although not shown, the image forming apparatus of the present invention preferably further includes static eliminating means for eliminating surface charges remaining on the photoconductor, and is preferably provided together with cleaning means.
As the static elimination means, an apparatus known in the art can be used.

Further, it is preferable that the image forming apparatus of the present invention further includes a separation means (separation claw 770) for separating the recording medium P from the photoconductor F.

(4-9) Operation of Image Forming Device The operation of the image forming device of the present invention will be described with reference to the above image forming device 700.
First, when the photoconductor F is rotationally driven in a predetermined rotation direction (arrow R direction) by the driving means, a charger provided on the upstream side of the photoconductor F in the rotation direction with respect to the imaging point of light by the exposure means 720. The surface of the photoconductor F is uniformly charged to a predetermined potential by the 710.

Next, the exposure means 720 irradiates the surface of the photoconductor F uniformly charged with light according to the image information. In the photoconductor 1, the surface charge of the light-irradiated portion is removed by this exposure, and a difference occurs between the surface potential of the light-irradiated portion and the surface potential of the non-light-irradiated portion. A latent image is formed.
Toner is supplied to the surface Fa of the photoconductor F on which the electrostatic latent image is formed from the developing device 730 provided on the downstream side in the rotation direction of the photoconductor 1 from the image forming point of the light by the exposure means 720 to perform the electrostatic latent image. The image is developed and a toner image is formed.

The transfer paper P is supplied to the transfer nip portion TN between the photoconductor F and the transfer charger 740 from the transfer direction (arrow W direction) of the transfer paper in synchronization with the exposure to the photoconductor F. The transfer charger 740 gives the supplied transfer paper P a charge having a polarity opposite to that of the toner, and the toner image formed on the surface Fa of the photoconductor F is transferred onto the transfer paper P.
The transfer paper P on which the toner image is transferred is conveyed to the fixing device 760 by the conveying means, and when passing through the contact portion between the heating roller 760a and the pressure roller 760b of the fixing device 760 and the fixing nip portion FN, the toner image is transferred. Is heated and pressurized and fixed on the transfer paper P to obtain a robust image. The transfer paper P on which the image is formed in this way is discharged to the outside of the image forming apparatus 700 by the conveying means.

On the other hand, the toner remaining on the surface Fa of the photoconductor F even after the transfer of the toner image by the transfer charger 740 is peeled off from the surface Fa of the photoconductor F by the cleaning blade 750a of the cleaner 750 and collected in the recovery casing 760b. NS.
The electric charge on the surface Fa of the photoconductor F from which the toner has been removed is removed, and the electrostatic latent image on the surface disappears. After that, the photoconductor F is further rotationally driven, and a series of operations starting from charging is repeated to continuously form an image.
When the image forming apparatus 700 is provided with the static eliminating means on the downstream side of the cleaner 750 and before reaching the charging means 710, the light from the static eliminating lamp of the static eliminating means efficiently charges the surface Fa of the photoconductor F. It is more reliably removed and the electrostatic latent image on the surface Fa of the photoconductor F disappears.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.
In Examples and Comparative Examples, each physical property value was measured by the method shown below.

[DSC measurement (endothermic peak temperature at the time of temperature rise: T1 and heat generation peak temperature at the time of temperature decrease: T2)]
Using a differential scanning calorimeter (Seiko Electronics Co., Ltd. (currently Hitachi High-Tech Science Co., Ltd.), model: DSC220), 1 g of a toner sample is heated to 150 ° C at a heating rate of 10 ° C / min, and then 150 ° C. Hold for 2 minutes, cool to 30 ° C. at a temperature lowering rate of 10 ° C./min, and measure the DSC curve. The endothermic peak temperature T1 (° C.) at the time of raising the temperature and the exothermic peak temperature T2 (° C.) at the time of lowering the temperature of the obtained DSC curve are obtained, and the temperature difference ΔT (° C.) between them is obtained.

[DSC measurement (glass transition temperature of binder resin: Tg]
Using the above differential scanning calorimeter, 1 g of the binder resin sample is heated at a heating rate of 10 ° C./min according to Japanese Industrial Standards (JIS) K7121-1987, and the DSC curve is measured. In the obtained DSC curve, a straight line extending the baseline on the high temperature side of the heat absorption peak corresponding to the glass transition to the low temperature side and a point where the gradient is maximized with respect to the curve from the rising portion of the peak to the apex. The temperature at the intersection with the drawn tangent line is defined as the glass transition temperature Tg (° C.).

[DSC measurement (transparent melting point of mold release agent: Tm]
Using the above differential scanning calorimeter, 1 g of the release agent sample was heated from a temperature of 20 ° C. to 200 ° C. at a heating rate of 10 ° C./min, and then rapidly cooled from 200 ° C. to 20 ° C. was repeated twice. Measure the DSC curve. The temperature of the endothermic peak corresponding to the melting of the DSC curve measured in the second operation is defined as the transparent melting point Tm (° C.) of the release agent.

[Flow tester measurement (melting temperature of binder resin: Tm)]
^{A load of 20 kgf / cm 2} (9) while heating 1 g of the binder resin sample at a heating rate of 6 ° C./min using a flow characteristic evaluation device (flow tester, manufactured by Shimadzu Corporation, model: CFT-100C). .8 × 10 ⁵ Pa) was given and the sample was drained from the die (nozzle diameter 1 mm, length 1 mm). The melting temperature Tm (° C.) is defined as the temperature at which half of the sample flows out.

[GPC measurement (peak top molecular weight: Mp)]
The peak top molecular weight (Mp) of the binder resin and the toner is measured by gel permeation chromatography (GPC) under the following conditions.
The peak top molecular weight refers to the molecular weight showing the maximum peak height in the chromatogram obtained by GPC measurement.
In the measurement of the molecular weight, a polyester resin is dissolved in tetrahydrofuran (THF) and the insoluble matter is filtered out with a glass filter and used as a sample solution.
(Device and conditions)
Equipment: Made by Tosoh Corporation, Model: HLC-8120
Column: Tosoh Corporation, TSK GEL GMH6 2 pieces Measurement temperature: 40 ° C
Sample solution: 0.25% by mass THF solution Injection amount: 100 μl
Detection device: Refractive index detector Reference material: Tosoh Corporation, standard polystyrene (TSK standard POLYSTYRENE) 12 points (molecular weight 500, 1050, 2800, 5970, 9100, 18100, 37900, 96400, 190000, 355000, 1090000 and 2890000)

[Material used]
The alphanumeric symbols at the beginning of each material indicate abbreviations.
The following was used as the release agent.
WAX-1: Ester wax (transparent melting point Tm: 76 ° C, manufactured by NOF CORPORATION, product name: WE-15)
WAX-2: Ester wax (transparent melting point Tm: 82 ° C, manufactured by NOF CORPORATION, product name: WEP-5)
WAX-3: Ester wax (transparent melting point Tm: 79 ° C, manufactured by NOF CORPORATION, product name: WE-14)
WAX-4: Ester wax (transparent melting point Tm: 71 ° C, manufactured by NOF CORPORATION, product name: WE-12)
WAX-5: Paraffin wax (transparent melting point Tm: 75 ° C, manufactured by Nippon Seiro Co., Ltd., product name: HNP10)
WAX-6: FT (Fischer-Tropsch) (transparent melting point Tm: 90 ° C, manufactured by Nippon Seiro Co., Ltd., product name: FNP90)

As the associative silica, silica having the following particle size and degree of association was used from the products of the X-24-9470 series (manufactured by Shin-Etsu Chemical Co., Ltd.) and the Quattron PL series (manufactured by Fuso Chemical Industry Co., Ltd.) (Si-A1 to 9).
Further, silica TG-C191 (manufactured by Cabot Corporation) was used as the comparative spherical large particle size silica (Si-A10).
Si-A1: Associative silica (average primary particle size 60 nm, degree of association 2.5, average secondary particle size 150 nm)
Si-A2: Associative silica (average primary particle size 70 nm, degree of association 2.1, average secondary particle size 150 nm)
Si-A3: Associative silica (average primary particle size 75 nm, degree of association 1.8, average secondary particle size 140 nm)
Si-A4: Associative silica (average primary particle size 45 nm, degree of association 3.0, average secondary particle size 150 nm)
Si-A5: Associative silica (average primary particle size 35 nm, association degree 4.0, average secondary particle size 150 nm)
Si-A6: Associative silica (average primary particle size 40 nm, degree of association 2.5, average secondary particle size 105 nm)
Si-A7: Associative silica (average primary particle size 35 nm, association degree 2.5, average secondary particle size 90 nm)
Si-A8: Associative silica (average primary particle size 115 nm, degree of association 2.5, average secondary particle size 300 nm)
Si-A9: Associative silica (average primary particle size 160 nm, association degree 2.5, average secondary particle size 400 nm)
Si-A10: Spherical large particle size silica (average primary particle size 110 nm, average secondary particle size 110 nm)

The following was used as the small particle size silica.
Si-B1: Average primary particle size 7 nm, manufactured by Aerosil, Name: R976S
Si-B2: Average primary particle size 12 nm, manufactured by Aerosil, Name: R974
Si-B3: Average primary particle size 30 nm, manufactured by Aerosil, name: NAX50

The following amorphous polyester resins (resins A to F) were used as the binder resin.
(Resin A)
Polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane 1750 g, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane 1625 g, terephthalic acid 1245 g, 133 g of dodecenyl succinic anhydride, 384 g of trimellitic acid and 10 g of tin octylate were placed in a 10 liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube and a stirrer, and reacted at a temperature of 220 ° C. for 8 hours. Then, the reaction was carried out under reduced pressure (4 to 8 kPa), and the resin was taken out at a predetermined softening point to obtain a resin A having a glass transition point of 65 ° C., a softening temperature of 140 ° C. and a peak top molecular weight of Mp12000.

(Resin B)
Polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane 3500 g, fumaric acid 1160 g and tin octylate 10 g, 10 liter four-necked with nitrogen introduction tube, dehydration tube and stirrer After putting it in a flask and reacting at a temperature of 220 ° C. for 8 hours, the reaction was carried out under reduced pressure (4 to 8 kPa), the resin was taken out at a predetermined softening point, the glass transition point was 55 ° C., and the softening temperature was 95 ° C. , A resin B having a peak top molecular weight of Mp5400 was obtained.

(Resin C)
In the same manner as in Resin B, the reaction time after depressurization was adjusted and the resin was taken out at a predetermined softening point to obtain Resin C having a glass transition point of 50 ° C., a softening temperature of 90 ° C. and a peak top molecular weight of Mp3900.
(Resin D)
In the same manner as in Resin B, the reaction time after depressurization was adjusted and the resin was taken out at a predetermined softening point to obtain Resin D having a glass transition point of 48 ° C., a softening temperature of 85 ° C. and a peak top molecular weight of Mp3400.
(Resin E)
In the same manner as in Resin B, the reaction time after depressurization was adjusted and the resin was taken out at a predetermined softening point to obtain Resin E having a glass transition point of 60 ° C., a softening temperature of 105 ° C. and a peak top molecular weight of Mp6400.
(Resin F)
In the same manner as in Resin B, the reaction time after depressurization was adjusted and the resin was taken out at a predetermined softening point to obtain Resin F having a glass transition point of 60 ° C., a softening temperature of 110 ° C. and a peak top molecular weight of Mp8000.

(Example 1)
<Material mixing / kneading / crushing / classification>
Bound resin: Resin A (peak top molecular weight Mp12,000, melting temperature Tm140 ° C, glass transition temperature Tg65 ° C, abbreviation: resin A) 45% by mass
: Resin B (peak top molecular weight Mp 5,400, melting temperature Tm95 ° C, glass transition temperature Tg55 ° C, abbreviation: resin B) 45% by mass
Colorant: Carbon black (manufactured by Cabot Corporation, product name: Regal1330)
6% by mass
Release agent: Ester wax (transparent melting point Tm: 76 ° C, manufactured by NOF CORPORATION, product name: WE-15, abbreviation: WAX-1) 3% by mass
Charge control agent: Salicylic acid compound (Orient Chemical Industry Co., Ltd., product name: Bontron E-84) 1% by mass

Using an air flow mixer (Henchel Mixer, manufactured by Mitsui Mining Co., Ltd. (currently Nippon Coke Industries Co., Ltd.), model: FM20C), the above materials are premixed for 5 minutes, and then a twin-screw extruder (manufactured by Ikegai Co., Ltd., A melt-kneaded product was obtained by melt-kneading under the conditions of a cylinder set temperature of 110 ° C., a barrel rotation speed of 200 rpm, and a raw material supply speed of 15 kg / hour using a model (PCM30 type) [mixing / kneading step].
The obtained melt-kneaded product was cooled by a drum flaker and then coarsely pulverized using a cutting mill (manufactured by Orient Co., Ltd., model: VM-16) to obtain a coarsely pulverized product [coarse pulverization step].
Next, the obtained coarsely pulverized product was finely pulverized using a jet crusher (manufactured by Nippon Pneumatic Industries Co., Ltd., model: IDS-2) to obtain a finely pulverized product [fine pulverization step].
The obtained finely pulverized product was classified using an elbow jet classifier (manufactured by Nittetsu Mining Co., Ltd., model: EJ-LABO) to obtain toner particles having an average primary particle size of 6.5 μm [classification step]. ..

<External processing>
To 100 parts by mass of the obtained toner mother particles, 0.7 parts by mass of small particle size silica (average primary particle size 7 nm, manufactured by Aerosil Co., Ltd., name: R976S, abbreviation: Si-B1) is added, and the obtained mixture is flown. Using a mixer (Henchel Mixer, manufactured by Mitsui Mining Co., Ltd. (currently Nippon Coke Industries Co., Ltd.), model: FM20C), the mixture was mixed for 2 minutes under the setting conditions of the tip speed of the stirring blades of 40 m / sec [first external addition step]. ..
Next, 1.0 part by mass of associative silica Si-A1 (average primary particle diameter 60 nm, degree of association 2.5, average secondary particle diameter 150 nm) was further added, and the obtained mixture was added to the stirring blade at a tip speed of 40 m /. Mixing for 2 minutes under the setting condition of seconds [second external particle step].
In this way, an external toner was obtained by a two-step external addition treatment.

<Preparation of developer>
The obtained external toner and the ferrite core carrier (volume average particle diameter 40 μm, manufactured by Powdertech Co., Ltd.) were mixed with a V-type mixer (stock) so that the external toner concentration was 7% by mass with respect to the total amount of the developing agent. It was put into a product manufactured by Tokuju Kosakusho Co., Ltd., trade name: V-5), and mixed for 30 minutes to obtain a developer.

(Examples 2 to 25 and Comparative Examples 1 to 5)
An external toner and a developer were obtained in the same manner as in Example 1 except that the associative silica, the release agent and the small particle size silica shown in Tables 1 and 2 were used.

(Example 26)
An external toner and a developer were obtained in the same manner as in Example 1 except that resin C (peak top molecular weight Mp 3,900, melting temperature Tm 90 ° C., glass transition temperature Tg 50 ° C.) was used instead of resin B.

(Example 27)
An external toner and a developer were obtained in the same manner as in Example 1 except that the resin D (peak top molecular weight Mp3,400, melting temperature Tm85 ° C., glass transition temperature Tg48 ° C.) was used instead of the resin B.

(Example 28)
An external toner and a developer were obtained in the same manner as in Example 1 except that resin E (peak top molecular weight Mp 6,400, melting temperature Tm 105 ° C., glass transition temperature Tg 60 ° C.) was used instead of resin B.

(Example 29)
An external toner and a developer were obtained in the same manner as in Example 1 except that resin F (peak top molecular weight Mp8,000, melting temperature Tm110 ° C., glass transition temperature Tg60 ° C.) was used instead of resin B.

(Example 30)
An external toner and a developer were obtained in the same manner as in Example 1 except that the <external addition treatment> was changed to simultaneous addition / mixing of small particle size silica and associative silica as follows.
To 100 parts by mass of the obtained toner mother particles, 0.7 parts by mass of small particle diameter silica (Si-B1) and 1.0 part by mass of associated silica (Si-A1) were added, and the obtained mixture was mixed with an air flow mixer. Was mixed for 4 minutes under the setting condition of the tip speed of the stirring blade of 40 m / sec to obtain an external toner.

(Example 31)
An external toner and a developer were obtained in the same manner as in Example 1 except that small particle size silica (Si-B1) was not added in the (first external addition step) of the <external addition treatment>.

[evaluation]
The filming resistance, heat-resistant storage characteristics, and seizure phenomenon of the toner and developer produced in Examples 1 to 31 and Comparative Examples 1 to 5 are evaluated by the following methods, and a comprehensive evaluation is performed based on the results of these three evaluations. rice field.

[Evaluation 1: Filming resistance]
The prepared developer and toner were filled in each of the developing apparatus and the toner cartridge of a color multifunction device (manufactured by Sharp Corporation, model: BP-20C25) equipped with a charging roller. Next, the temperature is 25 ° C. and the humidity is 25 ° C. so that a square solid image (ID = 1.45 to 1.50) having a side of 10 mm is formed at three points in the axial direction of the developing roller. A continuous print test of 50,000 sheets was performed on A4 paper under a 5% environment.
After that, a solid image (ID: 1.6 to 1.8) and a halftone (HT) image (ID: 0.5 to 0.7) are output on A3 paper, and the obtained image is visually observed. , Filming resistance was evaluated according to the following criteria.

◎ (Excellent): No image defects (white streaks, etc.) in both solid and HT images, and no streaks are observed on the surface of the photoconductor ○ (Good): Image defects (white streaks, etc.) in both solid and HT images No, but some streaks are observed on the surface of the photoconductor △ (Yes): There are no image defects (white streaks, etc.) in the solid image, but slight image defects (white streaks, etc.) can be confirmed in the HT image. Partial streaks are observed on the surface of the photoconductor × (impossible): Defects (white streaks, etc.) can be confirmed in both the solid image and the HT image, and streaks are observed on the entire surface of the photoconductor.

[Evaluation 2: Heat-resistant storage]
The heat-resistant storage stability was evaluated based on the presence or absence of agglomerates after high-temperature storage.
20 g of the prepared toner was weighed (total toner weight: g), placed in a plastic container having a capacity of 50 mL, sealed, and left at a temperature of 50 ° C. for 72 hours. Then, the toner was taken out, classified with a 230 mesh sieve, and the toner remaining on the sieve was weighed (weight on the toner sieve: g).
The ratio of the weight on the toner sieve to the total weight of the toner weighed in advance was determined as the residual amount (%), and the heat-resistant storage stability was evaluated according to the following evaluation criteria.
◎ (excellent): No agglutination. Residual amount is less than 0.5% ○ (Good): A small amount of agglutination. Residual amount is 0.5% or more and less than 7% Δ (possible): A large amount of agglutination. Residual amount is 7% or more and less than 12% × (impossible): A large amount of agglutination. The residual amount is 12% or more. The lower the residual amount value, the more the toner does not block and the toner matrix particles are sufficiently coated with the coating layer.

[Evaluation 3: Burn-in phenomenon]
The prepared developer and toner were filled in each of the developing apparatus and the toner cartridge of a color multifunction device (manufactured by Sharp Corporation, model: BP-20C25) equipped with a charging roller. Next, the temperature is 30 ° C. and the humidity is 30 ° C. so that a square solid image (ID = 1.45 to 1.50) having a side of 10 mm is formed at three points of the center portion and both end portions in the axial direction of the developing roller. A continuous print test of 50,000 sheets was performed on A4 paper under an environment of 80%. At that time, the image densities at the initial stage and after 50,000 sheets were measured using a colorimetric color difference meter (spectrometer, manufactured by X-Light, model: 504), and the image densities at the initial stage and after 50,000 sheets were measured. The difference (ΔID) was measured, and the seizure phenomenon was evaluated according to the following criteria.

◎ (excellent): There is no decrease in concentration (ΔID is less than 0.1), and
No toner fusion on the surface of the developing roller ○ (Good): There is no decrease in concentration (ΔID is less than 0.1), and
Toner fusion is observed on the surface of the developing roller Δ (possible): There is a slight decrease in concentration (ΔID is 0.1 or more and less than 0.2), and
Toner fusion is observed on the surface of the developing roller × (impossible): The concentration drops significantly (ΔID: 0.2 or more), and
Toner fusion is observed on the surface of the developing roller

[Comprehensive judgment]
Based on the above evaluation results, a comprehensive judgment was made according to the following criteria.
◎ (excellent): All evaluation items are ◎ (available)
○ (Good): There is ○ in one evaluation item (Available)
△ (possible): There is △ in one evaluation item (available)
× (impossible): There is × even in one evaluation item (cannot be used)
Tables 1 and 2 show the materials used for preparing the toners and developing agents of Examples and Comparative Examples, and Tables 1 and 2, and Tables 3 and 4 show the physical properties and evaluation results of the obtained toners and developing agents.

The following can be seen from Tables 1 to 4.
(1) The two-component developer (Examples 1 to 31) containing a toner having the requirements of the present invention has filming resistance even when both the reverse development method and the contact charging roller method are adopted. Excellent, capable of suppressing image deterioration and forming a stable image over a long period of use (2) On the other hand, a two-component developer (Comparative Examples 1 to 5) containing a toner that does not meet the requirements of the present invention has toner performance. Is inferior to the two-component developer containing the toner with the requirements of the present invention (3), and the two-component developer containing the toner with the other preferable requirements of the present invention has even better performance (3). 4) From the comparison of Examples 1 and 4 to 7, the filming resistance is excellent by setting the degree of association of the associated silica in the range of 2.0 to 3.0. (5) Of Examples 1 and 8 to 11. By comparison, when the average secondary particle size of the associated silica is less than 100 nm, the heat-resistant storage stability and the seizure phenomenon tend to deteriorate, and when it exceeds 300 nm, the filming resistance tends to deteriorate. (6) Examples 1 and 12 From the comparison of ~ 15, it can be seen that the filming resistance is excellent when the ester wax in the toner matrix particles is in the range of 0.5 to 5.0% by mass. If it exceeds 5.0% by mass, the heat-resistant storage property and the seizure phenomenon tend to worsen.

(7) From the comparison of Examples 1, 16 and 17, the filming resistance tends to deteriorate when the average primary particle size of the small particle size silica exceeds 15 nm. (8) From the comparison of Examples 1 and 18 to 21 When the content of the associated silica is less than 0.2% by mass, the heat-resistant storage property and the seizure phenomenon tend to deteriorate, and when it exceeds 2.0% by mass, the filming resistance tends to deteriorate ( 9) From the comparison of Examples 1, 22 to 25 and 31, it can be seen that the filming resistance is excellent when the content of the small particle size silica is in the range of 0.2 to 1.5% by mass. Further, when it is less than 0.2% by mass, the heat-resistant storage property and the seizure phenomenon also tend to deteriorate. (10) From the comparison of Examples 1 and 26 to 29, the peak top molecular weight (Mp) in the gel permeation chromatography (GPC) measurement. ) Tends to deteriorate the heat-resistant storage stability and the seizure phenomenon when it is less than 4000, and the filming resistance tends to deteriorate when it exceeds 6500. The first external addition step of adding and mixing small particle size silica as an additive component and externally adding the small particle size silica to the toner mother particles, and as a second external additive component to the obtained toner mother particles. Further excellent filming resistance can be obtained by further adding and mixing the associated silica and having a second externaling step of externally adding the associated silica to the toner mother particles.

700 Image forming device (laser printer)
710 Charging means (charger)
711 power supply (high voltage application device)
720 Exposure means 730 Developing means (developer)
730a Development roller 730b Casing 740 Transfer means (transfer charger)
741 High voltage application device 750 Cleaning means (cleaner)
750a Cleaning blade 750b Recovery casing 760 Fixing means (fixing device)
760a Heating roller 760b Pressurized roller 770 Separation means (separation claw)
780 housing
F Electrophotographic Photoreceptor F1 Hypokeimenon (Conductive Support)
Fa Photoreceptor surface D Developer (toner)
α1 Rotation axis α2 Rotation axis R Arrow (Rotation direction of electrophotographic photosensitive member)
P Recording medium (recording paper or transfer paper)
W arrow (conveying direction of recording medium)
H Horizontal direction V Vertical direction TN Transfer nip part FN Fixing nip part

G Charging member (charging roller)
G1 conductive support G2 elastic layer G3 resistance layer

Claims (9)

It is composed of at least toner matrix particles and an external additive added to the surface thereof.
The external additive contains associative silica, and the toner mother particles contain an ester wax as a release agent.
A toner characterized in that the temperature difference between the endothermic peak temperature and the exothermic peak temperature is 15 to 30 ° C. in differential scanning calorimetry (DSC). The toner according to claim 1, wherein the associative silica has an average secondary particle size of 100 to 300 nm and an association degree of 2.0 to 3.0. The toner according to claim 1 or 2, wherein the ester wax is contained in the toner matrix particles in a proportion of 0.5 to 5.0% by mass. The toner according to any one of claims 1 to 3, wherein the external additive further comprises small particle size silica having an average primary particle size of 15 nm or less. The toner according to claim 4, wherein the associative silica and the small particle size silica are contained in proportions of 0.2 to 2.0% by mass and 0.2 to 1.5% by mass, respectively, with respect to the toner mother particles. .. The toner according to any one of claims 1 to 5, wherein the toner has a peak top molecular weight (Mp) of 4000 to 6500 in gel permeation chromatography (GPC) measurement. The method for producing toner according to any one of claims 4 to 6.
The first external addition step of adding and mixing the small particle size silica as the first external particle component to the toner mother particles and externally adding the small particle size silica to the toner mother particles, and the obtained toner mother. A method for producing a toner, which comprises a second externaling step of adding and mixing the associated silica as a second external additive component to the particles and externally adding the associated silica to the toner mother particles. .. A developer comprising the toner according to any one of claims 1 to 6 and a carrier. An image forming apparatus equipped with the toner according to any one of claims 1 to 6 and a charging roller system as a method for charging the surface of the photoconductor.

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