JP4401904B2 - Toner for electrostatic charge development and image forming method - Google Patents

Description

  The present invention relates to a toner and an image forming method for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing, and the like.

  Recent printer devices have become higher resolution devices, for example, devices with 600, 800, 1200 dpi resolution. Along with this, there is a demand for a development system that can cope with high resolution and high definition (that is, high image quality). On the other hand, downsizing of printers and higher printing speeds are progressing year by year.

As a developing device for realizing high image quality, a thin layer developing device using an elastic developing blade method has been developed. The thin layer developing device has a developing blade made of an elastic body in contact with the developing sleeve with high pressure,
1) Toner coat amount W on the developing sleeve W [W: toner coat mass (cm) per 1 cm ^{2 of} developing sleeve surface] is reduced, and 2) high Q / M [Q / M: unit for toner on the developing sleeve By giving the toner charge amount (μQ) per mass (g)], the toner can be sufficiently charged in a short time.

However, since the thin layer developing device presses the elastic developing blade against the developing sleeve with a high linear pressure, the toner may be seriously damaged by pressure or heat at the contact portion between the developing sleeve and the developing blade.
Further, the surface roughness of the developing sleeve of the thin layer developing device tends to be reduced in order to reduce the toner coat amount W on the developing sleeve. When the surface roughness of the developing sleeve is reduced, the ability to transport toner is reduced, so that the toner circulation in the developing container in the developing device tends to deteriorate. Therefore, the toner circulation in the thin layer developing device is vigorously agitated to prevent the toner circulation from deteriorating. However, there is a problem that the toner in the developing container is greatly damaged by the strong stirring.

  Furthermore, in order to improve the resolution and sharpness and to faithfully reproduce the latent image as a response to higher image quality, a toner having a smaller particle size (for example, a particle size of about 4 to 8 μm) has been developed. . When the toner has a reduced particle size, the fluidity of the toner itself is deteriorated, so that the toner circulation in the developing container is deteriorated, and the specific surface area is increased, so that it is easily affected by heat. Therefore, there has been a problem that the deterioration of the toner is easily promoted.

  On the other hand, as described above, machines such as printers are required to be further downsized due to demands for energy saving and office space saving. For this reason, it is inevitably required to reduce the size of the developing container for storing toner, and the amount of toner that can be stored in the developing container has been reduced. Accordingly, there is a need for a toner that can print out a large number of sheets with a small amount, in other words, a toner that can perform the printout of the same image in a smaller amount, that is, a low consumption toner.

  Further, as a means for increasing the printing speed of the developing device, it has been known to make the shape of the toner used more spherical. This is because by making the toner spherical (for example, by reducing unevenness on the surface of the toner particles), the chargeability and transferability of the toner can be improved. Further, since the bulk density of the toner is reduced by making the toner spherical, a low consumption toner can be obtained.

Known methods for producing a spherical toner include spray granulation, solution dissolution, and polymerization (see, for example, Patent Documents 1 to 4). However, in order to produce toner by these methods, large-scale equipment is required, which is not preferable in terms of production efficiency. Further, the toner produced by these methods cannot sufficiently reduce the toner consumption.
Further, immediately after starting the developing device, the toner is not sufficiently charged due to friction between the developing sleeve and the developing blade, so the density of the formed image is often low. As the toner continues to be durable, the toner is gradually frictionally charged to increase the charge amount, and the resulting image density is improved. On the other hand, a charge-up phenomenon in which the charge amount increases extremely may occur. . Therefore, it is particularly important to prevent toner charge-up in a high-speed developing device having a high printing speed. From the viewpoint of suppressing this charge-up, there is room for improvement in the toner produced by the above method.

  As a method for producing a spheroidized toner, a method of modifying the shape and surface property of toner particles produced by a pulverization method by thermal or mechanical impact is also known (for example, Patent Document 5). ~ 8). However, even if the shape of the toner particles is modified (spheroidized) by these methods, it is still not sufficient to reduce the amount of toner consumed, and it may cause adverse effects such as a decrease in developability. there were.

In addition, since the spherical toner has a small contact area between the toner particle surface and the external additive particles, a high pressure is concentrated on the contact portion, and when strong stirring is performed in the developing container, Due to the contact between the toners or between the toner and the stirring material, the external additive particles existing on the surface of the toner particles are easily embedded in the toner particles. Further, since the surface of the toner particles of the spheroidized toner has few concave portions, there are few places where the external additive added to the toner particle surface escapes. Therefore, the external additive externally added to the surface of the toner particles is more easily buried when the toners contact each other or between the toner and the stirring material.
Furthermore, in the case of toner particles having a lot of irregularities on the surface (that is, the degree of spheroidization is low), the external additive that was present in the depressions on the surface of the toner particles is deposited near the outer surface of the toner particles due to friction, The buried external additive can be supplemented. On the other hand, since the spherical toner particles have few concave portions on the surface, there is a problem that the deterioration of the toner is accelerated.

  On the other hand, external additives (for example, inorganic fine particles such as various metal oxides, particularly silica and alumina, for the purpose of adjusting the chargeability and fluidity of the toner and obtaining better developability, cleaning properties, transferability, etc.) In general, a toner in which toner particles are externally added to toner particles is known. In particular, a toner is proposed in which two types of inorganic fine powders having different BETs are externally added to toner particles in order to suppress toner deterioration (see Patent Document 9). However, since the toner proposed here has a small amount of inorganic fine powder having a small BET that has been subjected to a hydrophobization treatment, the fluidity is poor, and in particular, the image quality at the time of first printing in a high-temperature and high-humidity environment is poor. Tend. In addition, inorganic fine particles that have not been hydrophobized, such as alumina, are added in almost the same amount as silica that has been hydrophobized. In this case, the toner charge amount is lowered, and the density of the formed image is likely to be lowered.

Furthermore, in order to obtain high fluidity and high chargeability, a toner is proposed in which a mixture of inorganic fine powders (particularly silica) subjected to different surface treatments is externally added to toner particles (Patent Documents 10 to 14). reference).
Patent Documents 10, 11 and 14 propose toners to which a mixture of silica subjected to hydrophobic treatment and silica not subjected to hydrophobic treatment is added. However, since the toner proposed here is mixed with silica that has not been hydrophobized, it is highly hygroscopic, especially under high-temperature and high-humidity environments, causing charge attenuation and fluidity deterioration. In some cases, the density of the generated image may be reduced, or it may lead to a phenomenon such as fading.
Patent Documents 12 and 13 propose toners to which two types of silica having different degrees of hydrophobicity are externally added. However, the toner proposed here has a small difference in the degree of hydrophobicity between the two types of externally added silica, so that the chargeability is good, but the toner may be charged up. As a result, the density of the formed image may be reduced, or image defects such as ghosts may occur under low temperature and low humidity. In addition, although the toners proposed in these are improved in chargeability and fluidity, there is room for improvement in terms of measures against toner deterioration when the printing speed is increased.

Furthermore, in order to suppress the deterioration of the toner when the printing speed is increased, two types of inorganic fine particles which have been subjected to different surface treatments, and two types of inorganic fine particles having different particle sizes (BET) are used as toner particles. A toner externally added to the toner is proposed (Patent Documents 15 to 19). However, these two types of inorganic fine particles have an insufficient balance between hydrophobicity and particle size as an external additive for the spherical toner particles employed in a high-speed developing device with an increased printing speed. . Therefore, the toner proposed here still has room for improvement in chargeability, durability stability, developability such as ghost.
Japanese Patent Laid-Open No. 3-84558 JP-A-3-229268 Japanese Patent Laid-Open No. 4-1766 JP-A-4-102862 JP-A-2-87157 JP-A-10-97095 JP-A-11-149176 JP-A-11-202557 Japanese Patent No. 2759480 Japanese Patent Laid-Open No. 3-192267 JP-A-4-204658 JP-A-11-231567 JP 2001-209209 A JP 2002-207315 A Japanese Patent No. 2786898 Japanese Patent Laid-Open No. 11-143118 JP 2001-305783 A JP 2002-287409 A JP-A-5-113688

An object of the present invention is to provide a toner in which the above problems are solved. That is, a toner containing more spherical toner particles and hydrophobic silica having specific physical properties as an external additive, having good chargeability and charge stability, high fluidity, and low consumption. It is an object of the present invention to provide toner by an efficient means.
Further, by using the toner, the solid toner has excellent image stability and the white spot of the solid image caused by free silica, or immediately after the developing device is started, the charge amount rises slowly with the conventional toner. Another object of the present invention is to provide an image forming method in which the density of an image to be formed does not decrease even under a situation where the charge amount is insufficient.

That is, the first aspect of the present invention relates to the following electrostatic charge developing toner.
A toner for electrostatic charge development containing toner particles containing at least a binder resin and a colorant, and an external additive containing at least hydrophobic silica A and hydrophobic silica B,
The toner particles have an average circularity of 0.930 to 0.970;
The hydrophobic silica A is a hydrophobized dry silica, which is treated with a silane coupling agent and then treated with silicone oil.
Hydrophobic silica B is a hydrophobized dry silica, which has been hydrophobized with alkoxysilanes,
A specific surface area BET _A of the hydrophobic silica A, the relationship between the specific surface area BET _B of the hydrophobic silica B is, 1.2 × a _{BET B ≦ BET A ≦ 5 ×} BET B, of the hydrophobic silica A The degree of hydrophobicity WET _A is 77 % or more and less than 90%, and the degree of hydrophobicity WET _B of the hydrophobic silica _B is 20% or more and less than 50%, and 25% <WET _A −WET _B <70% An electrostatic charge developing toner according to claim 1.

The second aspect of the present invention relates to the following image forming method.
1) a charging process in which a voltage is applied to the charging means to charge the object to be charged; 2) a process in which an electrostatic image is formed on the charged object to be charged; 3) a toner image obtained by developing the electrostatic image with toner. A developing process for forming the toner image on the charged body, 4) a transferring process for transferring the toner image on the charged body to the transfer material with or without the intermediate transfer body, and 5) a toner image on the transfer material. An image forming method including a fixing step of fixing by heating,
In the developing step, the member to be charged is opposed to a developer carrying member that carries the toner, and the developer carrying member is provided on the developing sleeve, a magnetic field generating means included in the developing sleeve, and the developing sleeve. An elastic blade for forming a toner layer on the surface of the developing sleeve, and the toner includes toner particles containing at least a binder resin and a colorant, and hydrophobic silica A having a different specific surface area BET And an external additive containing at least hydrophobic silica B,
The toner particles have an average circularity of 0.930 to 0.970;
The hydrophobic silica A is a hydrophobized dry silica, which is treated with a silane coupling agent and then treated with silicone oil.
Hydrophobic silica B is a hydrophobized dry silica, which has been hydrophobized with alkoxysilanes,
The relationship between the specific surface area BET _A hydrophobic silica A and a specific surface area BET _B of the hydrophobic silica B is a _{1.2 × BET B ≦ BET A ≦} 5 × BET B,
The hydrophobic silica A has a hydrophobicity WET _A of 77 % or more and less than 90%, the hydrophobic silica B has a hydrophobicity WET _B of 20% or more and less than 50%, and 25% <WET _A − An image forming method, wherein the toner is an electrostatic charge developing toner having WET _B <70%.

<External additive contained in toner of the present invention>
As described above, the external additive contained in the toner of the present invention contains at least two types of hydrophobic silicas, hydrophobic silica A and hydrophobic silica B, and may contain other optional components. Both hydrophobic silica A and hydrophobic silica B can be produced by subjecting dry silica to a hydrophobization treatment, and the production will be described in detail later.

The hydrophobic silica A and the hydrophobic silica B have different specific surface areas BET.
The specific surface area BET _A of the hydrophobic silica A is preferably 70 to 350 m ² / g, and the specific surface area BET _B of the hydrophobic silica B is preferably 30 to 90 m ² / g. When the BET _{B of the} hydrophobic silica B is less than 30 m ² / g, the particle diameter is too large, so that it tends to be detached (for example, free) from the toner particles, and white spots may occur in the obtained image. On the other hand, if the BET _{A of the} hydrophobic silica A exceeds 350 m ² / g, the particle diameter is too small, and thus the toner containing it tends to deteriorate.

Hydrophobic silica A and hydrophobic silica B have different specific surface areas BET, but specific surface area BET _A of hydrophobic silica _A (hereinafter simply referred to as “BET _A ”) and specific surface area BET _B of hydrophobic silica _B ( Hereinafter, simply referred to as “BET _B ” is characterized by having the relationship of the following formula (α).
1.2 x BET _B ≤ BET _A ≤ 5 x BET _B ··· Formula (α)

It is considered that the hydrophobic silica A having a relatively high specific surface area BET can impart fluidity and chargeability to the toner containing it as an external additive. On the other hand, it is surmised that the hydrophobic silica B having a relatively low specific surface area can act as a void material for preventing the deterioration of the toner containing it as an external additive.
By having BET _A and BET _B in the relationship of the above formula (α), external additives (including hydrophobic silica A and B) are less likely to be released from the toner particles, so that charging is good and charge-up is suppressed. Thus, it is possible to obtain a toner that is further prevented from being deteriorated.

On the other hand, when the relationship between BET _A and BET _B is 1.2 × BET _B > BET _A , the particle size difference between the hydrophobic silicas A and B is small. The image density is likely to decrease due to toner deterioration. When the relationship between BET _A and BET _B is BET _A > 5 × BET _B , the particle size difference between the silica particles on the toner particle surfaces is too large, and the charge amount cannot be balanced. Therefore, the image density is likely to be lowered, and the silica released from the toner particles may aggregate to form an aggregate. Therefore, white spots are likely to occur in the printed solid black image.

Further, the relationship between BET _A and BET _B is more preferably 1.3 × BET _B <BET _A <4 × BET _B , and 1.4 × BET _B <BET _A <2.5 × BET _B. More preferably. This is because it is possible to easily achieve both high chargeability and deterioration resistance of the toner regardless of the printing environment (including humidity and temperature) and process speed.

Here, the specific surface area BET of the hydrophobic silicas A and B can be determined by a low temperature gas adsorption method by a dynamic constant pressure method according to a BET method (preferably a BET multipoint method). For example, using a specific surface area measuring device “Gemini 2375 Ver. 5.0” (manufactured by Shimadzu Corporation), nitrogen gas is adsorbed on the surface of the sample (hydrophobic silica A or B) and measured using the BET multipoint method. By doing so, the BET specific surface area (m ² / g) can be calculated.

  Further, hydrophobic silica A and hydrophobic silica B contained in the toner of the present invention are characterized by having different degrees of hydrophobicity. Here, the degree of hydrophobicity of the hydrophobic silicas A and B means the degree of hydrophobicity measured by methanol wettability, and the explanation of the degree of hydrophobicity and the measuring method will be described in detail later.

The hydrophobicity WET _A (hereinafter simply referred to as “WET _A ”) of the hydrophobic silica A contained in the toner of the present invention is preferably 65 to 90%, more preferably 70 to 85%. .
When WET _A is higher than 90%, the hydrophobicity is too high, so that the toner containing silica A is likely to be charged up, and more likely to be overcharged particularly in a low humidity environment. Is likely to get worse. On the other hand, when the value of WET _A is less than 65%, the charge holding ability of the toner containing the silica A is lowered, fogging is likely to occur in the formed image, and the fluidity of the whole toner is lowered. Therefore, development failure due to fading is likely to occur.

The hydrophobicity WET _B (hereinafter, simply referred to as “WET _B ”) of the hydrophobic silica B contained in the toner of the present invention is preferably 20% to 50%, more preferably 30 to 50%. preferable.
Silica B having a WET _B of less than 20% is easily affected by humidity and tends to form an aggregate of silica particles with moisture as a nucleus. Prone to cause. Further, although silica B having a WET _B value larger than 50% is uniformly dispersed on the surface of the toner particles, the toner containing the silica B is difficult to be charged and easily causes a phenomenon such as sleeve ghost.

Moreover, hydrophobicity of the hydrophobic silica A WET _A, and hydrophobicity WET hydrophobic silica B
_B preferably satisfies the relationship “25% <WET _A −WET _B <70%”, and more preferably satisfies the relationship “30% ≦ WET _A −WET _B ≦ 50%”.

The relatively high hydrophobic hydrophobic silica A imparts high chargeability and high fluidity to the toner containing it, while the relatively low hydrophobic hydrophobic silica B contains excessive toner. Can be prevented from being charged. Therefore, the toner containing hydrophobic silicas A and B as external additives can suppress a decrease in image density due to charge-up, and can provide a durable image having a stable density even in long-term durability.
By making the difference between the hydrophobicity of hydrophobic silica _A (WET _A ) and the hydrophobicity of hydrophobic silica B (WET _B ) 25% to 70%, the hydrophobic silicas A and B are combined and added externally. Since the charged toner has a stable chargeability, it is possible to form a good image over a long period of time regardless of the environment, and an image formed immediately after starting the image forming apparatus and an image formed when the durability is stable. The difference in density can be reduced.
When the difference between WET _A and WET _B is 25% or less, the toner containing hydrophobic silicas A and B is likely to be charged up, and image density is likely to be lowered. Further, when the difference is 70% or more, the charge amount of the toner containing silica A and B is not stable. Therefore, the toner is formed when the density and durability of the image formed immediately after starting up the image forming apparatus are stable. This is likely to cause a problem that the density difference in image density increases.

The toner obtained by combining the hydrophobic silica A and the hydrophobic silica B having such a degree of hydrophobicity and externally adding to the toner particles can have high fluidity and charge stability. Even when it is applied to a high-speed developing device having a high process speed under the following conditions, an excessive increase in charge (charge-up) hardly occurs, so that a sleeve ghost hardly occurs and is not easily affected by temperature and humidity.
Here, the sleeve ghost is a ghost in which an image density difference occurs due to a difference in charge amount between toner newly supplied on the sleeve (new toner) and toner already on the sleeve (old toner). This means a phenomenon called negative ghost or positive ghost (see FIGS. 4 and 5).
When using conventional toner, especially in low-temperature and low-humidity environments and high-temperature and high-humidity environments, if the number of frictions on the sleeve in the high-speed developing device increases, the charge amount of the new toner and old toner when new toner is supplied There is a tendency that the difference between the two tends to increase, and sleeve ghost is likely to occur.

The degree of hydrophobicity WET _A or WET _B is determined when the degree of dispersion of hydrophobic silica A or B in a methanol-water mixed solvent (also referred to herein as “methanol wettability”) is a specific value. It means the methanol concentration of the mixed solvent. Here, the methanol wettability of the hydrophobic silica A or B is measured as the transmittance of a methanol-water mixed solution containing the hydrophobic silica A or B.
That is, WET _A or WET _B is a value obtained when the transmittance of a methanol-water mixed solution containing a specific amount of hydrophobic silica A or B is measured with light having a wavelength of 780 nm. Means the methanol concentration of the mixed solution.

  That is, the degree of hydrophobicity of hydrophobic silica A or B can be measured using a methanol drop transmittance curve. As a measuring device, for example, a powder wettability tester WET-100P manufactured by REHSCA (Resca) can be used, and examples of specific measuring operations include the methods exemplified below.

First, 70 ml of a hydrated methanol solution composed of 60% by volume of methanol and 40% by volume of water is placed in a container and dispersed with an ultrasonic disperser for 5 minutes to remove bubbles and the like in the solution. In this solution, 0.06 g of hydrophobic inorganic fine particles (hydrophobic silica A or B) as a specimen is added and suspended, and a sample solution for measuring the hydrophobic characteristics of the hydrophobic inorganic fine particles is prepared. As a container for preparing and measuring a sample solution, a glass flask having a circular diameter of 5 cm and a height of 88 mm can be used.
Next, while stirring the prepared sample liquid for measurement at a speed of 6.67 s ⁻¹ , methanol was added at 1.3 ml / min. The suspension is continuously added at a dropping speed of 1 to disperse the suspended hydrophobic inorganic fine particles in the solvent. While dropping methanol, the transmitted light intensity of light having a wavelength of 780 nm of the measurement sample is measured to obtain the transmittance, and a methanol dropping transmittance curve as shown in FIG. 3 is created. Here, the stirring can be performed using a magnetic stirrer (for example, a spindle having a length of 25 mm and a maximum diameter of 8 mm and having a Teflon (registered trademark) coating). Then, the methanol concentration when the transmittance is 80% is calculated as the degree of hydrophobicity of the hydrophobic silica.

  In the measurement of the degree of hydrophobicity by methanol wettability, when the degree of hydrophobicity of the hydrophobic silica A or B as the specimen is less than 60%, a hydrous methanol solution comprising 60% by volume of methanol and 40% by volume of water When the sample is added to the sample, it is immediately dispersed in the solvent, and a transmittance curve cannot be obtained. Therefore, when the hydrophobicity of the hydrophobic silica sample was less than 60%, the measurement was performed with the methanol concentration of the initial solution set to 0%.

  Hydrophobic silica A and hydrophobic silica B are contained in the toner of the present invention as external additives. The total content of hydrophobic silica A and hydrophobic silica B is 0 with respect to 100 parts by mass of toner particles. It is preferable that it is 0.5 mass part-5.0 mass parts. This is to obtain a toner having excellent deterioration resistance and good fluidity and chargeability.

  In addition, in a toner containing hydrophobic silica A and hydrophobic silica B, if the content of hydrophobic silica B having a relatively small specific surface area BET and low hydrophobicity is too large, the fluidity of the toner becomes extremely high. Since it falls, fading is likely to occur, and it is easy to be affected by humidity and the like, so that problems such as a decrease in the density of an image printed out under high temperature and high humidity are likely to occur. Therefore, when the mass of the hydrophobic silica A is 1, the mass of the hydrophobic silica B is preferably 0.05 to 0.7.

  In particular, hydrophobic silica A and hydrophobic silica B are externally added in the above ratio to toner particles having high circularity (for example, toner particles having an average circularity of 0.930 to 0.970), Even when applied to a developing device or an image forming apparatus that is compatible with high image quality and high speed, it is possible to obtain a toner that quickly rises in charge, hardly deteriorates, and does not cause a decrease in image density in long-term use.

Hydrophobic silica A and hydrophobic silica B can be produced by subjecting predetermined dry silica to a hydrophobic treatment. Here, the predetermined dry silica is silica fine powder, and is preferably dry silica called so-called dry silica or fumed silica produced by vapor phase oxidation of a silicon halogen compound. Among these, it is preferable that the dry silica has few silanol groups on the surface and inside the silica fine powder and has few production residues such as Na ₂ O and SO ₃ ²⁻ .
In the production process of the dry silica, for example, by using another metal halogen compound such as aluminum chloride or titanium chloride together with the silicon halogen compound, it is possible to obtain a composite fine powder of silica and another metal oxide. In this specification, dry silica includes those composite fine powders.

The hydrophobic silica B is produced by treating dry silica with alkoxysilane. Here, the alkoxysilane is an alkylalkoxysilane such as methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, etc. Compound: Phenyltrimethoxysilane, diphenyldiethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane and the like are mentioned, but not limited to these, and alkoxysilane compounds other than these are included. As a method for treating dry silica with these alkoxysilanes, ordinary methods can be used.
Moreover, the desired specific surface area BET _B and the degree of hydrophobicity WET _B can be imparted to the hydrophobic silica B by appropriately selecting the amount and type of the hydrophobizing agent and the hydrophobizing method.

On the other hand, the hydrophobic silica A can be produced by subjecting dry silica to a hydrophobic treatment using a conventionally known hydrophobic treatment agent. Preferred examples of the hydrophobizing agent include 1) silicone oil, 2) silicone varnish, and 3) silane coupling agent. By appropriately selecting the type and amount of these hydrophobizing agents and the hydrophobizing method, the desired specific surface area BET _A and the hydrophobizing degree WET _A can be imparted to the hydrophobic silica A.

  The 1) silicone oil is not limited, but examples thereof include those represented by the following general formula.

Specific examples of the silicone oil include dimethyl silicone oil, alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil, but are not limited thereto. .
The viscosity of the silicone oil is preferably 50 to 1000 mm ² / s at a temperature of 25 ° C. When it is less than 50 mm ² / s, it is partly volatilized by heating, and the charging characteristics of the toner containing it tend to deteriorate. If it exceeds 1000 mm ² / s, handling becomes difficult in terms of processing work.

  Any known method can be used as a treatment method using silicone oil. For example, dry silica and silicone oil are mixed using a mixer; silicone oil is sprayed on dry silica using a sprayer; silicone oil is dissolved in a solvent, and then dry silica is mixed in the solution. The method of doing is mentioned. However, the processing method is not limited to this.

As the 2) silicone varnish used for the production of the hydrophobic silica A, any known silicone varnish can be used. Examples thereof include KR-251 and KP-112 manufactured by Shin-Etsu Silicone, but are not limited thereto. Moreover, as a processing method by a silicone varnish, a well-known method can be used like a silicone oil process.

  Examples of 3) silane coupling agents used in the production of the hydrophobic silica A include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, and allyldimethylchlorosilane. , Allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate , Vinyldimethylacetoxysilamen, dimethyldiethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisilo Xane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule, each having one silicon atom per terminal unit And dimethylpolysiloxane containing a hydroxyl group bonded to.

  Furthermore, as a treatment form for producing hydrophobic silica A having high hydrophobic properties, it is preferable to treat dry silica in combination with a silane coupling agent and silicone oil or a silane coupling agent and silicone varnish. Among these, a mode in which 1) treatment with a silane coupling agent is performed first, and 2) treatment with silicone oil or silicone varnish is preferred. Among these, the form of treating with silicone oil after treating with hexamethyldisilazane is particularly preferable.

  The external additive containing the hydrophobic silica A and the hydrophobic silica B can be used as an external additive for any toner such as a color toner, a monochrome toner, a magnetic toner, and a nonmagnetic toner. Further, the external additive exhibits a desired effect even if it is used as an external additive for toner used in any of the development methods such as two-component development, magnetic one-component development, and non-magnetic one-component development.

<Toner particles contained in the toner of the present invention>
As described above, the toner particles contained in the toner of the present invention include at least a binder resin and a colorant, and may further include other optional components such as wax and a charge control agent.

  The particle diameter of the toner particles is preferably 3 μm or more from the viewpoint of image quality, and more preferably 8 μm or less from the viewpoint of dot reproducibility.

  The average circularity of the toner particles is preferably 0.930 to 0.970, more preferably 0.934 to 0.965, and still more preferably 0.940 to less than 0.960. Here, the average circularity of the toner particles is a value for quantitatively expressing the shape of the toner particles, and is an index of the degree of unevenness of the toner particles. When the toner particles are perfectly spherical, the average circularity is 1, and the more complicated the surface shape, the lower the average circularity.

  When the average circularity of the toner particles is increased, the fluidity of the toner containing the toner particles is increased, and the individual toners are easily moved freely. For this reason, since the circulation of the toner in the cartridge becomes good, the toner is easily frictionally charged, the rising of the charge is improved, and the toner can be uniformly charged. Further, a toner containing toner particles having a high average circularity tends to be in a denser state in an image developed using the toner particles. As a result, the toner concealment ratio with respect to the transfer material is increased, and a sufficient image density can be obtained even with a small amount of toner, so that the toner consumption can be reduced.

On the other hand, when the average circularity of the toner particles is lowered, the toner containing the toner particles tends to behave as an aggregate. Since the toner aggregate has unevenness in the charge amount at the concavo-convex portion, the charge amount may become extremely high, or the charge amount may not increase and may adversely affect the developability.

Therefore, if the average circularity of the toner particles is less than 0.930, the shape of the toner particles is distorted, so that the frictional charge of the toner containing the toner particles is not uniform and the absolute charge amount tends to be low. . For this reason, the density of an image printed out particularly under low temperature and low humidity conditions may be reduced, and negative ghosting and fogging may be deteriorated.
On the other hand, if the average circularity of the toner particles is larger than 0.970, the toner is excessively supplied onto the developing sleeve, and the toner is unevenly coated on the sleeve, so that a positive ghost due to overcharging is likely to occur. In addition, when the surface becomes smooth, the bulk density increases, and the toner is more easily clogged in the developing device, so that the density may be lowered due to fading.
Therefore, a toner containing toner particles having an average circularity in the above range has a uniform charge, a long-term stable and high image density, and by using this, there is no phenomenon such as ghost and fog, and good developability. Can be obtained.

  By externally adding the above-described external additive containing the hydrophobic silica A and the hydrophobic silica B to the toner particles having such a circularity, the external additive adheres evenly to the surface of the toner particles with less unevenness. Therefore, it is possible to obtain a toner whose charge rise is quick and charge-up is prevented.

The average circularity of the toner particles contained in the toner of the present invention is an average circularity measured by an image analysis method, and is preferably a value measured using a flow type particle image analyzer FPIA-2100 manufactured by Sysmex Corporation. is there.
After calculating the circularity of each particle, the analyzer “FPIA-2100” assigns each particle to 61 divided classes having a circularity of 0.4 to 1.0, and uses the center value and frequency of the dividing points. A calculation method (division method) for calculating the average circularity is used. The error of the average circularity calculated by the calculation method using the value of the average circularity calculated by this calculation method and the total circularity of each particle (summation method) is very small and can be substantially ignored. Degree. In the calculation of the average circularity of the toner particles in the present invention, a summation method may be used. However, for reasons of data handling such as shortening the calculation time and simplifying the calculation formula, the division method is used. Also good.
Furthermore, “FPIA-2100” that can be used for measuring the average circularity of the toner particles of the present invention is a thin layer of sheath flow compared to “FPIA1000” conventionally used for calculating the shape of the toner. Since the accuracy of toner shape measurement has been improved by increasing the magnification (7 μm → 4 μm), increasing the magnification of the processed particle image, and improving the processing resolution of the captured image (256 × 256 → 512 × 512), the fine particles Can be captured more reliably. Therefore, in calculating the average circularity of the toner particles of the toner of the present invention, it is preferable to use “FPIA-2100” which can obtain information on the shape and particle size distribution more accurately.

  As a specific measurement method, analysis is performed with the above-described analyzer in an environment of 23 ° C. and 60% RH, and a projected image of particles within a circle equivalent diameter range of 0.60 μm to 400 μm is analyzed. The length L is measured. From the measured perimeter, the circularity of the particles is determined by the following formula (β). Further, for the particles having a circle-equivalent system in the range of 3 μm to 400 μm, the total circularity of the particles and the number of the particles are obtained. Then, a value obtained by dividing the sum of the circularity by the number of particles is defined as an average circularity.

Formula (β)... Circularity a = L ₀ / L
[In the formula, L ₀ represents the circumference of a circle having the same projected area as the particle image, and L is 512 × 512.
The peripheral length of the particle projection image when image processing is performed at an image processing resolution of (pixels of 0.3 μm × 0.3 μm) is shown. ]

The detailed measurement procedure is described below. A surfactant (preferably alkylbenzene sulfonate) (0.1 to 0.5 ml) is added as a dispersant to water (200 to 300 ml) in a container from which impurities have been removed in advance, and a measurement sample is further added to 0.1%. Add ~ 0.5g. The suspension in which the sample is dispersed is dispersed with an ultrasonic oscillator for 2 minutes, so that the concentration of the dispersion is 0.2 to 1 million pieces / μl. For example, the following apparatus is used as the ultrasonic oscillator, and the following dispersion conditions are used.
UH-150 (manufactured by SMT Corporation)
OUTPUT level: 5
Constant mode

  The circularity distribution of the particles of the dispersion obtained above is measured. An outline of the measurement will be described below. The sample dispersion is passed through a flow path (expanding along the flow direction) of a flat and flat flow cell (thickness: about 200 μm). The strobe and the CCD camera are mounted on the flow cell so as to be opposite to each other so as to form an optical path that passes through the thickness of the flow cell. While the sample dispersion is flowing through the flow cell, strobe light is irradiated at 1/30 second intervals to obtain an image of particles dispersed in the sample dispersion. As a result, each particle is photographed as a two-dimensional image having a certain range parallel to the flow cell. From the area of the two-dimensional image of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter. From the projected area of the two-dimensional image of each particle and the perimeter of the projected image, the circularity of each particle is calculated using the circularity calculation formula (β). From the calculated circularity, the average circularity can be obtained as described above.

Further, the average surface roughness of the toner particles contained in the toner of the present invention is preferably 5.0 nm or more and less than 42.0 nm, more preferably 10.0 nm or more and less than 42.0 nm, and further preferably 15.0 nm or more and 40.40 nm. It is less than 0 nm.
When the toner particles have an appropriate surface roughness, an appropriate gap is generated between the toners, the fluidity of the toner can be improved, and better developability can be provided. In particular, a toner having excellent fluidity can be obtained by imparting the average surface roughness to toner particles having high circularity, which is one of the characteristics of the present invention.
When the average surface roughness of the toner particles is less than 5.0 nm, sufficient fluidity cannot be imparted to the toner containing the toner particles, fading may occur, and the image density may be lowered. If the average surface roughness of the toner particles is 45.0 nm or more, there are too many voids between the toner particles, so that external additives (including hydrophobic silicas A and B) are difficult to adhere uniformly to the toner particles, The external additive is liberated and white spots are likely to occur in the formed image.

  The maximum height difference of the toner particles contained in the toner of the present invention is preferably 50 nm or more and less than 450 nm, more preferably 100 nm or more and less than 450 nm, from the viewpoint of imparting better fluidity to the toner. Preferably, it is 150 nm or more and less than 400 nm. The maximum height difference of the toner particles means a difference in height between the most convex point and the most concave point on the toner surface, and the measurement method will be described later.

When the external additive containing the hydrophobic silica A and the hydrophobic silica B is externally added to the toner particles having such a surface roughness, the hydrophobicity having a small specific surface area BET (large particle size) is formed on the toner particle surface. Silica B and hydrophobic silica A having a large BET (small particle size) can be uniformly dispersed and closely adhered. Therefore, since the large particle size silica (hydrophobic silica B) can more easily exert the effect as a buffer material, it is possible to obtain a toner whose deterioration is suppressed to a minimum even in a high-speed developing device having a high process speed.
In particular, hydrophobic silica A and B are toner particles having an average circularity of 0.930 to 0.970 and an average surface roughness measured by a scanning probe microscope of 5.0 nm or more and less than 45.0 nm. By adding externally, the rise of concentration is good, the concentration is low due to charge-up, ghost phenomenon does not occur in low-temperature, low-humidity, high-temperature, high-humidity environments, and deterioration is minimal even when durable for a long time. Thus, it is possible to obtain a toner that does not generate white spots in a printed image.

In the present invention, the average surface roughness of toner particles and the maximum height difference of toner particles are measured using a scanning probe microscope. For example, the measurement apparatus and measurement conditions described below may be used to measure a 3 μm square area on the surface of the toner particles as a measurement target.
Measuring device: SPI3800N (manufactured by Seiko Instruments Inc.)
Measuring unit: SPA400
Measurement mode: DFM (resonance mode)
Cantilever: SI-DF40

  In the specification of the present application, the average surface roughness means a “center line average roughness” defined in JIS-B0601 expanded in three dimensions so that it can be applied to the measurement surface. That is, it is a value obtained by averaging the absolute values of deviations from the reference plane to the designated plane, and is expressed by the following equation.

In this specification, the maximum height difference of the toner particles can be obtained from the difference between the maximum value and the minimum value of the Z data in the specified plane in the above formula.

The method for producing the toner particles contained in the toner of the present invention is not particularly limited, but it is preferably produced by subjecting the raw toner particles produced by any method to surface modification. By appropriately adjusting the surface modification conditions, it is possible to impart desired circularity and surface roughness to the toner particles.
Hereinafter, a surface modifying apparatus for modifying the surface of raw toner particles and a method for modifying the surface of raw toner particles using the surface modifying apparatus will be described in detail with reference to the drawings.

FIG. 1 shows an example of a surface modification apparatus used in the present invention, and FIG. 2 shows an example of a top view of a dispersion rotor 36 (see FIG. 1) that is a rotating body that rotates at high speed. The surface modification apparatus shown in FIG. 1 is (1) a casing, and (2) a rotating body on a disk having a plurality of square disks or cylindrical pins 40 on the upper surface and rotating at high speed. Dispersion rotor 36 attached to the rotating shaft, (3) A liner 34 (having grooves on the surface of the liner) disposed on the outer periphery of the dispersion rotor 36 at a constant interval and provided with a number of grooves on the surface. (4) Classification rotor 3 which is a means for classifying the surface-modified raw material into a predetermined particle size
1, (5) Cold air inlet 35 for introducing cold air, (6) Raw material supply port 33 for introducing raw material to be treated, (7) Opening and closing so that the surface modification time can be freely adjusted A discharge valve 38 installed as possible, (8) a product discharge port 37 for discharging the processed powder, (9) a classification rotor 31 as classification means, a dispersion rotor 36 as surface modification means, And a first space and a second space surrounded by the liner 34, and (10) a cylindrical guide link 39 that partitions the first space 41 and the second space 42.
It is preferable that the surface modification device further has (11) a jacket (not shown) through which cooling water or antifreeze can be passed.

A gap portion between the dispersion rotor 36 and the liner 34 is referred to as a surface modification zone, and the classification rotor 31 and the rotor peripheral portion are referred to as a classification zone.
That is, the first space is a space for introducing the raw toner particles or the particles subjected to the surface modification treatment in the surface modification zone into the classification zone, and the second space is used for fine powder by the classification rotor 31. This is a space for introducing classified particles to the surface modification zone.

  The classifying rotor 31 may be installed in the vertical direction as shown in FIG. 1 or in the horizontal direction. Further, the number of classification rotors 31 may be one as shown in FIG. 1 or two or more.

The minimum distance between the dispersion rotor 36 and the liner 34 in the surface modification apparatus is preferably 0.5 mm to 15.0 mm, and more preferably 1.0 mm to 10.0 mm.
The rotational peripheral speed of the dispersion rotor 36 is preferably 75 m / sec to 200 m / sec, and more preferably 85 m / sec to 180 m / sec.
The minimum distance between the upper part of the rectangular disk or cylindrical pin 40 installed on the upper surface of the dispersion rotor in the surface modifying apparatus and the lower part of the cylindrical guide ring 39 is preferably 2. It is 0 mm-50.0 mm, More preferably, it is 5.0 mm-45.0 mm.

  In the present invention, it is preferable in terms of toner particle productivity that the finely pulverized toner collision surfaces of the dispersion rotor 36 and the liner 34 in the surface modifying apparatus are subjected to wear resistance treatment. Here, the abrasion-resistant treatment method for the pulverized surface is not limited at all. Further, the shapes of the dispersion rotor 36 and the liner 34 in the surface modification apparatus are not limited at all.

By using the surface modification device, toner particles contained in the toner of the present invention can be produced. An example of a specific procedure is shown below. Raw material toner particles, which are raw materials, are charged from the raw material supply port 33 with the discharge valve 38 closed. The charged raw material toner particles are first sucked by a blower (not shown) and guided to the classification rotor 31 for classification. The classified “fine powder” having a predetermined particle size or less is continuously discharged and removed from the fine powder collection port 32 to the outside of the apparatus. A circulating flow generated by the dispersion rotor 36 along the second space 42) is led to the surface modification zone.
The raw material (that is, coarse powder) guided to the surface modification zone is subjected to a surface modification treatment by receiving a mechanical impact force between the dispersion rotor 36 and the liner 34. The surface-modified particles subjected to the surface modification treatment are introduced from the cold air inlet 35 and placed on the cold air passing through the machine, and are guided to the classification zone along the outer periphery (first space 41) of the guide ring 39. Then, classification is performed again by the classification rotor 31. Again, fine powder having a predetermined particle size or less is discharged out of the apparatus, and coarse powder having a predetermined particle size or more is returned to the surface modification zone again, and repeatedly subjected to surface modification treatment. After a predetermined time has elapsed, the discharge valve 38 is opened, and the surface modified toner particles are collected from the product discharge port 37.

The toner particle surface modification method using the surface modification apparatus described above is characterized in that the fine particle component can be removed simultaneously with the surface modification of the toner particles. As a result, it is possible to suppress the ultrafine particles present in the raw material toner particles from sticking to the surface of the toner particles. Therefore, it is possible to effectively obtain toner particles having a desired circularity and average surface roughness and having a minimum amount of ultrafine particles.
On the other hand, if a surface modification method that does not remove fine powder at the same time as the surface modification is used, the amount of ultrafine particles in the toner particles after the surface modification increases, and in addition, the surface modification of toner particles Due to mechanical and thermal influences, the ultrafine particle component adheres to the surface of toner particles having an appropriate particle size. As a result, protrusions due to the adhering fine powder component are generated on the surface of the toner particles after the surface modification, so that it is difficult to obtain toner particles having a desired circularity and average surface roughness.

  The surface modification time in the surface modification apparatus (cycle time, that is, the time from the supply of the raw toner particles to the opening of the product discharge port) is preferably 5 to 180 seconds, and 15 seconds to 120. More preferably, it is seconds. When the surface modification time is less than 5 seconds, the modification time is too short, and thus the surface modification may not be sufficiently performed. Also, if the modification time exceeds 180 seconds, the modification time is too long, so that the toner particles are fused in the apparatus due to heat generated during surface modification, or the processing capacity of the surface modification apparatus is reduced. There is.

Further, in the toner particle surface modification method, the cold air temperature T1 introduced into the surface modification apparatus is preferably 5 ° C. or less, more preferably 0 ° C. or less, and −5 ° C. or less. More preferably. This is to prevent in-machine fusion due to heat generated during surface modification.
In addition, it is preferable that the cold air introduce | transduced in this surface modification apparatus is dehumidified from the surface of the condensation prevention in an apparatus. The cold air can be dehumidified using a known dehumidifier. The dew point temperature of the cold air to be introduced is preferably −15 ° C. or lower, and more preferably −20 ° C. or lower.

As described above, the surface reforming apparatus used in the present invention preferably includes a jacket through which cooling water or antifreeze liquid can flow, and a refrigerant (preferably a cooling water solvent, more preferably ethylene glycol) is provided in the jacket. It is preferable to carry out the surface modification treatment while passing the antifreeze solution. By cooling the jacket through the cooling medium in the apparatus, the toner particles can be prevented from being fused in the apparatus by heat generated by the surface modification treatment.
Here, the temperature of the refrigerant passed through the jacket provided in the surface reforming apparatus is preferably 5 ° C. or less, more preferably 0 ° C. or less, and still more preferably −5 ° C. or less.

  In the method for producing toner particles using the surface modifying apparatus of the present invention, the temperature T2 behind the classification rotor in the surface modifying apparatus is preferably 60 ° C. or less, preferably 50 ° C. or less. This is to prevent the toner particles from being fused in the machine by heat generated during the surface modification.

In the production of the toner particles of the present invention, the raw material toner particles used in the surface modification device remove fine powder and coarse powder to some extent from the finely pulverized toner finely divided in the vicinity of a desired particle size (for example, air current It is preferable that the particles be obtained by using a classifier. Here, examples of the airflow type classification plan include Elbow Jet (manufactured by Nippon Steel Industries Co., Ltd.).
By using the raw material toner particles obtained by removing fine powder and coarse powder from the finely pulverized toner, it is possible to improve the dispersion of the toner particles in the surface modifying apparatus. In particular, the fine powder component in the toner particles has a large specific surface area and a relatively high charge amount, so that it is difficult to separate from the toner particles. For this reason, the fine powder component may not be appropriately classified by the classification rotor of the surface modification device. Accordingly, by using raw material toner particles obtained by removing fine powder components from the finely pulverized toner in advance, individual toner particles can be easily dispersed in the surface modifying device, and the ultra fine powder components can be appropriately classified. It is preferable to obtain toner particles having a desired particle size distribution by classification and removal.

  The raw material toner particles (for example, raw material toner particles obtained by removing fine powder and coarse powder from a finely pulverized toner using an airflow classifier) are toners having a particle size distribution measured by a Coulter counter method of less than 4 μm. The cumulative value of the number average distribution of particles is 10% or more and less than 50%, preferably 15% or more and less than 45%, more preferably 15% or more and less than 40%. This is because the ultrafine powder component is effectively removed by the surface modification apparatus of the present invention.

  As described above, the toner particles contained in the toner of the present invention are produced, for example, by subjecting raw material toner particles obtained by removing fine powder and coarse powder from a finely pulverized toner to a surface modification treatment. The finely pulverized toner can be produced by mixing and / or melt-kneading a binder resin, a colorant, and other optional components, and pulverizing them.

The finely pulverized toner can be produced by any method. For example, a binder resin, if necessary, a release agent, a charge control agent, and magnetic powder are sufficiently mixed by a mixer (including a Henschel mixer and a ball mill). The obtained mixture is melt-kneaded using a heat kneader (including a heating roll, a kneader, an extruder, etc.) so that the binder resin and the release agent are mutually compatible. A finely pulverized toner product is produced by dispersing a colorant and, optionally, a magnetic substance in this compatible material, cooling and solidifying, and then pulverizing with a pulverizer and classifying with a spheronizer as necessary. I can do it.
As the mixer, Henschel mixer (manufactured by Mitsui Mining); Super mixer (manufactured by Kawata); Ribocorn (manufactured by Okawara Seisakusho); Nauter mixer, turbulizer, cyclomix (manufactured by Hosokawa Micron); Spiral pin mixer (Manufactured by Taiheiyo Kiko Co., Ltd.);
Examples of the thermal kneader include KRC kneader (manufactured by Kurimoto Iron Works); Bus co-kneader (manufactured by Buss); TEM type extruder (manufactured by Toshiba Machine); TEX twin-screw kneader (manufactured by Nippon Steel Works) PCM kneading machine (Ikegai Iron Works); Three roll mill, mixing roll mill, kneader (Inoue Seisakusho); Needex (Mitsui Mining); MS pressure kneader, Nider Ruder (Moriyama Seisakusho) ); Banbury mixer (manufactured by Kobe Steel).
Examples of the pulverizer include counter jet mill, micron jet, inomizer (manufactured by Hosokawa Micron); IDS type mill, PJM jet pulverizer (manufactured by Nippon Pneumatic Industrial Co., Ltd.); cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); (Manufactured by Nisso Engineering Co., Ltd.); SK Jet Oh Mill (manufactured by Seishin Enterprise Co., Ltd.); Kryptron (manufactured by Kawasaki Heavy Industries Ltd.); .
The classifiers include a class seal, a micron classifier, a speck classifier (manufactured by Seishin Enterprise); a turbo classifier (manufactured by Nisshin Engineering); a micron separator, a turbo flex (ATP), and a TSP separator (manufactured by Hosokawa Micron). ); Elbow Jet (manufactured by Nippon Steel Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Industrial Co., Ltd.); YM Microcut (manufactured by Yaskawa Shoji Co., Ltd.).

  As described above, the finely pulverized toner is produced using a binder resin as one of the raw materials. The binder resin used here has a glass transition temperature (Tg) of 45 to 80 ° C. (more preferably 50 to 50 ° C.). 70 ° C.).

Specific examples of the binder resin include styrene resins, styrene copolymer resins, polyester resins, polyol resins, polyvinyl chloride resins, phenol resins, natural modified phenol resins, natural resin modified maleic resins, acrylic resins, methacrylic resins, and methacrylic resins. Preferred examples include resins, polyvinyl acetate, silicone resins, polyurethane resins, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone indene resins, petroleum resins, and the like.
More preferably, [1] styrene copolymer resin and [2] polyester resin are mentioned.

  Examples of the [1] styrene copolymer resin include a copolymer of a styrene monomer and one or more arbitrary comonomers. Comonomers combined with styrene monomers include styrene derivatives such as vinyl toluene; acrylic acid; methyl acrylate, ethyl acrylate, butyl acrylate, decyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, and the like. Acrylic acid ester; methacrylic acid; methacrylic acid ester such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate; maleic acid; dicarboxylic acid having a double bond such as butyl maleate, methyl maleate, dimethyl maleate Acetic acid ester; Acrylamide; Acrylonitrile; Methacrylonitrile; Butadiene; Vinyl chloride; Vinyl esters such as vinyl acetate and vinyl benzoate; Ethylene such as ethylene, propylene and butylene Emissions olefin; vinyl methyl ketone, such as vinyl vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl propionate ether. These comonomers can be used alone or in combination of two or more.

  The styrenic copolymer may have an acid value. Having an acid value means having a carboxylate in the resin structure. The binder resin having an acid value can be produced by copolymerizing a styrene monomer and a monomer raw material containing an unsaturated carboxylic acid monomer or an anhydride thereof. The unsaturated carboxylic acid monomer or anhydride thereof can be used alone or in combination of two or more. The content of the unsaturated carboxylic acid monomer with respect to 100 parts by mass of the monomer raw material for the binder resin is preferably 0.1 to 20 parts by mass, and more preferably 0.2 to 15 parts by mass.

Examples of the unsaturated carboxylic acid monomer or anhydride thereof include the following.
(1) Acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, cinnamic acid, vinyl acetic acid, isocrotonic acid, angelic acid, and α- or β-alkyl derivatives thereof,
(2) Unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, alkenyl succinic acid, itaconic acid, mesaconic acid, dimethylmaleic acid, dimethylfumaric acid, and monoester derivatives or anhydrides thereof.

  It is particularly preferable to use a monoester derivative of an unsaturated dicarboxylic acid as the unsaturated carboxylic acid monomer in order to control the acid value. Examples of monoester derivatives of unsaturated dicarboxylic acid include monomethyl maleate, monoethyl maleate, monobutyl maleate, monooctyl maleate, monoallyl maleate, monophenyl maleate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate Monoesters of α, β-unsaturated dicarboxylic acids such as monophenyl fumarate; monobutyl n-butenyl succinate, monomethyl n-octenyl succinate, monoethyl n-butenylmalonate, monomethyl n-dodecenyl glutarate, Illustrative examples include monoesters of alkenyl dicarboxylic acids such as monobutyl n-butenyl adipate.

  [1] The styrene copolymer resin is produced by an addition polymerization method. Examples of the polymerization method that can be used here include a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method.

Among these, the emulsion polymerization method is a polymerization method in which a monomer that is almost insoluble in water is dispersed in the aqueous phase as smaller particles in an emulsifier, and a water-soluble polymerization initiator is used. In this method, the heat of reaction can be easily adjusted, and since the phase in which the polymerization is carried out (oil phase consisting of a polymer and a monomer) and the aqueous phase are different, the termination reaction rate is low, and as a result, the polymerization rate is high. A product having a high degree of polymerization is obtained. Furthermore, 1) the polymerization process is relatively simple, and 2) the polymerization product is fine particles, so that it is easy to mix with colorants, charge control agents, and other additives, and toner production is easy. For this reason, there is a preferable aspect as a method for producing a binder resin for toner. However, impurities are easily mixed into the polymer produced due to the added emulsifier, and operations such as salting out are required to separate the polymer. In order to avoid this inconvenience, it is preferable to use a suspension polymerization method.

  In the suspension polymerization method, it is preferable to perform polymerization in a reaction system in which 100 parts by mass of an aqueous solvent, 100 parts by mass or less (preferably 10 to 90 parts by mass) of a monomer raw material containing a styrene monomer, and a dispersant are mixed. Examples of the dispersant that can be used include polyvinyl alcohol, polyvinyl alcohol part saponified product, calcium phosphate, and the like, and usually 0.05 to 1 part by mass with respect to 100 parts by mass of the aqueous solvent. The polymerization temperature is suitably 50 to 95 ° C., but is appropriately selected depending on the initiator used and the type of the target polymer.

  As described above, the styrene copolymer resin is produced by polymerizing a monomer raw material containing a styrene monomer, and the polymerization can be performed using a polymerization initiator. As the polymerization initiator, a polyfunctional polymerization initiator as exemplified below can be used alone or in combination with a monofunctional polymerization initiator. The polymerization initiator is preferably used in an amount of 0.05 to 2 parts by mass with respect to 100 parts by mass of the monomer raw material from the viewpoint of polymerization efficiency.

As a specific example of the polyfunctional polymerization initiator,
1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,3-bis- (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di- ( t-butylperoxy) hexane, tris- (t-butylperoxy) triazine, 1,1-di-t-butylperoxycyclohexane, 2,2-di-t-butylperoxybutane, 4,4-di -T-butylperoxyvaleric acid-n-butyl ester, di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate, di-t-butylperoxytrimethyladipate, 2,2- Bis- (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-t-butylperoxyoctane, n-butyl-4,4 2 functional groups having a polymerization initiation function such as a peroxide group in one molecule, such as di (t-butylperoxy) valerate, α, α′-bis (t-butylperoxydiisopropyl) benzene, and various polymer oxides. Polyfunctional polymerization initiators having the above, and peroxides in one molecule such as diallyl peroxydicarbonate, t-butylperoxymaleic acid, t-butylperoxyallylcarbonate and t-butylperoxyisopropyl fumarate And a polyfunctional polymerization initiator having both a functional group having a polymerization initiation function such as a group and a polymerizable unsaturated group.

  Among these polyfunctional polymerization initiators, more preferred are 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, Di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate, 2,2-bis- (4,4-di-t-butylperoxycyclohexyl) propane and t-butylperoxyallyl carbonate It is.

These polyfunctional polymerization initiators may be used in combination with a monofunctional polymerization initiator in order to satisfy various performances required in the production of a binder resin for toner.
Specific examples of monofunctional polymers include organic peroxides such as benzoyl peroxide, dicumyl peroxide, t-butyl peroxycumene, di-t-butyl peroxide, and azobisisobutyronitrile. Examples include azo or diazo compounds such as diazoaminoazobenzene.

  The monofunctional polymerization initiator used in combination may be added to the monomer raw material at the same time as the addition of the polyfunctional polymerization initiator, but preferably the polyfunctional polymerization initiator alone is first subjected to the polymerization reaction, After the half-life indicated by the polyfunctional polymerization initiator has elapsed, the monofunctional polymerization initiator is added. This is because the efficiency of the polyfunctional polymerization initiator can be kept appropriate.

  [1] The styrene copolymer resin may form a crosslinked structure. In order to form a crosslinked structure, a monomer material containing a styrene monomer may be further polymerized with a crosslinking monomer. The content of the crosslinkable monomer in the monomer raw material is 0.00001 to 1 part by mass, preferably 0.001 to 0.05 part by mass with respect to 100 parts by mass in total of the monomer components other than the crosslinkable monomer.

As the crosslinkable monomer, a monomer having two or more polymerizable double bonds in the molecule is preferably used. Specific examples include 1) aromatic divinyl compounds (eg, divinylbenzene, divinylnaphthalene, etc.); 2) diacrylate compounds linked by alkyl chains (eg, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate). 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and acrylates of these compounds in place of methacrylate); 3) Diacrylate compounds linked by an alkyl chain containing an ether bond (eg, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 400 Acrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and acrylates of the above compounds replaced with methacrylate); 4) diacrylate compounds linked by a chain containing an aromatic group and an ether bond (for example, , Polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) propane diacrylate, and compounds of these 5) Polyester type diacrylate compounds (for example, trade name MANDA (Nippon Kayaku)) are mentioned.
Polyfunctional crosslinkable monomers include pentaerythritol acrylate, trimethylol ethane triacrylate, trimethylol propane triacrylate, tetramethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate, and acrylates of these compounds as methacrylates. Alternatives: triallyl cyanurate, triallyl trimellitate and the like.

  Among these crosslinkable monomers, those particularly preferably used include aromatic divinyl compounds (particularly divinylbenzene) and diacrylate compounds linked by a chain containing an aromatic group and an ether bond.

  The styrene copolymer resin can also be produced using a bulk polymerization method or a solution polymerization method. The bulk polymerization method can obtain a low molecular weight polymer by polymerizing at a high temperature to increase the termination reaction rate, but has a problem that the reaction is difficult to control. In this regard, the solution polymerization method is preferable because a polymer having a desired molecular weight can be easily obtained under mild conditions by adjusting the amount of the initiator and the reaction temperature. In particular, the solution polymerization method under a pressurized condition is preferable in that the amount of the initiator used can be minimized, and the influence of the remaining initiator can be suppressed.

  On the other hand, the [2] polyester resin can be produced by a condensation polymerization method that is generally known as a method for producing a polyester resin. That is, it can be produced by subjecting a monomer raw material containing a polyhydric alcohol (preferably a dihydric alcohol component) and a polycarboxylic acid component (preferably a divalent carboxylic acid component) to a condensation polymerization reaction.

The content of the polyhydric alcohol component in the monomer raw material is preferably 40 to 60 mol%, and more preferably 45 to 55 mol% with respect to the entire monomer raw material. On the other hand, the content of the polyvalent carboxylic acid component is preferably 60 to 40 mol%, and more preferably 55 to 45 mol%.
Moreover, it is preferable that a polyhydric alcohol component and carboxylic acid component more than trivalence are 5-60 mol% with respect to the whole monomer raw material.

  Examples of the dihydric alcohol component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1, Examples include 6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, bisphenol derivatives represented by the following general formula (A), and diols represented by the following formula (B).

  Examples of the divalent carboxylic acid component include benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride or anhydrides thereof, lower alkyl esters; alkyls such as succinic acid, adipic acid, sebacic acid, and azelaic acid. Dicarboxylic acids or anhydrides thereof, lower alkyl esters; alkenyl succinic acids such as n-dodecenyl succinic acid, n-dodecyl succinic acid or alkyl succinic acids or anhydrides thereof, lower alkyl esters; fumaric acid, maleic acid, citraconic acid, itaconic acid Dicarboxylic acids such as unsaturated dicarboxylic acids or anhydrides thereof, lower alkyl esters;

  In the production of the polyester resin, it is preferable to use a trihydric or higher alcohol component and / or a trivalent or higher acid component acting as a crosslinking component together with the dihydric alcohol component and the divalent carboxylic acid component.

  Examples of the trihydric or higher polyhydric alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4- Butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxybenzene Etc.

  Examples of the trivalent or higher polyvalent carboxylic acid component include trimellitic acid, pyromellitic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7- Naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane , Tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, empole trimer acid, and their anhydrides, lower alkyl esters; tetracarboxylic acid represented by the following general formula (C), etc. And polyhydric carboxylic acids such as anhydrides and lower alkyl esters thereof and derivatives thereof.

  As described above, the toner particles contained in the toner of the present invention include a colorant, and examples of the colorant include magnetic iron oxide and metal. The content of magnetic iron oxide and / or metal in the toner particles is preferably 20 to 200 parts by mass, more preferably 25 to 150 parts by mass with respect to 100 parts by mass of the resin component.

  Examples of magnetic iron oxides include iron oxides such as magnetite, maghemite, and ferrite. Examples of metals include metals such as iron, cobalt, and nickel, and these metals and aluminum, cobalt, copper, lead, magnesium, manganese, selenium, and titanium. , Alloys of metals such as tungsten, vanadium and mixtures thereof.

A preferable example of the colorant is magnetic iron oxide containing a non-ferrous element on the surface or inside thereof. The content of the non-ferrous element in the magnetic iron oxide is preferably 0.05 to 10% by mass and more preferably 0.1 to 5% by mass with respect to the iron element.
The non-ferrous element is preferably an element selected from magnesium, aluminum, silicon, phosphorus, and sulfur, and silicon element is particularly preferable. Magnetic iron oxide containing silicon element can improve the chargeability of the toner containing it.
The magnetic iron oxide includes the following lithium, beryllium, boron, germanium, titanium, zirconium, tin, lead, zinc, calcium, barium, scandium, vanadium, chromium, manganese, cobalt, copper, nickel, gallium, cadmium, Metal elements such as indium, silver, palladium, gold, mercury, platinum, tungsten, molybdenum, niobium, osmium, strontium, yttrium, and technetium can also be included.
Further, the magnetic iron oxide may be treated with a silane coupling agent, a titanium coupling agent, titanate, aminosilane, or the like, if necessary.

The colorant contained in the toner particles may be any suitable pigment or dye.
Examples of the pigment include carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue, and indanthrene blue. These pigments are used in an amount necessary and sufficient to maintain the optical density of the fixed image. The content of the pigment in the toner particles is 0.1 to 20 parts by mass, preferably 0 to 100 parts by mass of the binder resin. 2 to 10 parts by mass.
Examples of the dye include azo dyes, anthraquinone dyes, xanthene dyes, and methine dyes. The content of the dye in the toner particles is 0.1 to 20 parts by mass, preferably 0.3 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  The toner particles contained in the toner of the present invention may contain a wax. Examples of the wax are 1) aliphatic hydrocarbon wax such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax, and 2) fat such as oxidized polyethylene wax. Oxides of aromatic hydrocarbon waxes, 3) block copolymers thereof, 4) plant waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax, 5) animal systems such as beeswax, lanolin, whale wax 6) Mineral waxes such as ozokerite, ceresin and petrolactam, 7) Waxes based on aliphatic esters such as montanic ester wax and castor wax, 8) Fats such as deoxidized carnauba wax And those obtained by deoxidizing part or all of the group ester.

Further, as the wax, 1) saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkyl carboxylic acids having a long-chain alkyl group, 2)
Unsaturated fatty acids such as brassic acid, eleostearic acid, valinalic acid, 3) stearyl alcohol, eicosyl alcohol, behenyl alcohol, kaunavir alcohol, seryl alcohol, melyl alcohol, or alkyl alcohols having a long chain alkyl group 4) Polyhydric alcohols such as sorbitol, 5) Aliphatic amides such as linoleic acid amide, oleic acid amide, lauric acid amide, 6) Methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid Amide, saturated aliphatic bisamide such as hexamethylenebisstearic acid amide, 7) ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-diole Unsaturated fatty acid amides such as irsevacinamide, 8) aromatic bisamides such as m-xylene bis stearamide, N, N′-distearylisophthalamide, 9) calcium stearate, calcium laurate, zinc stearate, Aliphatic metal salts such as magnesium stearate (generally referred to as metal soap), 10) Wax grafted to aliphatic hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid, 11) Behenine Examples include partially esterified products of fatty acids and polyhydric alcohols such as acid monoglycerides, and 12) methyl ester compounds having hydroxyl groups obtained by hydrogenating vegetable oils and fats.

  In addition, the wax is treated with a press sweating method, a solvent method, a recrystallization method, a vacuum distillation method, a supercritical gas extraction method or a melt liquid crystal deposition method to sharpen its molecular weight distribution, and the treatment reduces the wax. Those obtained by removing molecular weight solid fatty acid, low molecular weight solid alcohol, low molecular weight solid compound and other impurities from the wax are also preferably used.

Specific examples of the wax that can be used as a release agent include Biscol (registered trademark) 330-P, 550-P, 660-P, TS-200 (Sanyo Chemical Industries), High Wax 4
00P, 200P, 100P, 410P, 420P, 320P, 220P, 210P, 110P (Mitsui Chemicals), Sazol H1, H2, C80, C105, C77 (Schumann Sazol), HNP-1, HNP-3, HNP- 9, HNP-10, HNP-11, HNP-12 (Nippon Seiki Co., Ltd.), Unilin (registered trademark) 350, 425, 550, 700, Unicid (registered trademark), Unicid (registered trademark) 350, 425, 550 700 (Toyo Petrolite Co., Ltd.), wood wax, beeswax, rice wax, candelilla wax, carnauba wax (available from Celalica NODA).

  The toner particles contained in the toner of the present invention may contain a charge control agent. Here, the charge control agent may be either a negative charge control agent or a positive charge control agent.

Examples of negative charge control agents include 1) metal complexes of monoazo dyes (for example, JP-B-41-20153, JP-B-42-27596, JP-B-44-6397, JP-B-45-26478, etc.), 2) Nitrohumine Acid and its salt, 3) C.I. I. Dyes and pigments such as 14645 (for example, JP-A-50-13338), 4) metal complexes of salicylic acid, naphthoic acid, dicarboxylic acid such as Zn, Al, Co, Cr, Fe, Zr, etc. 5) sulfonated copper Phthalocyanine pigment, 6) styrene oligomer introduced with nitro group and halogen, 7) chlorinated paraffin, 8) nigrosine dye, 9) metal salt of naphthenic acid or higher fatty acid, 10) alkoxylated amine, 11) quaternary ammonium Salt compounds, and the like.
These negative charge control agents are also described in, for example, JP-B-55-42752, JP-B-58-41508, JP-B-58-7384, and JP-B-59-7385.

  Particularly, an azo metal complex represented by the following general formula (I) and a basic organic compound represented by the following general formula (II), which are excellent in dispersibility and effective in reducing the density stability and fog of the image. An acid metal complex is preferably exemplified.

  Of these negative charge control agents, the azo metal complexes represented by the above formula (I) are more preferred. In particular, an azo-type iron complex whose central metal is Fe is preferable, and examples of the azo-type iron complex include complexes represented by the following general formula (III) and the following general formula (IV).

  Specific examples of the azo iron complex represented by the general formula (III) include azo iron complexes (1) to (6), and specific examples of the azo iron complex represented by the general formula (IV). An azo type iron complex (13) is mentioned.

  Specific examples of the azo chromium complex compound which is a complex represented by the above general formula (I) and whose central metal is chromium are shown in the following (7) and (8).

  Specific examples of the charge control agent represented by the general formula (II) are shown in the following (9) to (12).

  These metal complex compounds that are negative charge control agents can be contained alone or in combination of two or more in the toner particles. The content of the metal complex compound in the toner particles is preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the binder resin. This is for imparting appropriate chargeability to the toner containing the toner.

  Specific examples of preferable negative charge control agents include, for example, Spiron Black TRH, T-77, T-95 (Hodogaya Chemical Co., Ltd.), BONTRON (registered trademark) S-34, S-44, S-54. , E-84, E-88, E-89 (Orient Chemical Co.).

On the other hand, positive charge control agents include 1) nigrosine and its modified products by fatty acid metal salts, 2) tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, 3) tetrabutylammonium tetrafluoroborate, etc. Quaternary ammonium salts, and onium salts such as phosphonium salts and analogs thereof, and lake pigments thereof, 4) triphenylmethane dyes and lake pigments thereof (as rake agents, phosphotungstic acid, phosphomolybdic acid, Phosphotungstic molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.) 5) metal salts of higher fatty acids, 6) diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide I , 7) dibutyltin tin borate, dioctyl tin borate, diorgano tin borate such as dicyclohexyl tin borate, and the like.
One kind selected from these positive charge control agents can be used alone, or two or more kinds can be used in combination.

  Specific examples of preferable positive charge control agents include TP-302, TP-415 (Hodogaya Chemical Co., Ltd.), BONTRON (registered trademark) N-01, N-04, N-07, P-51 ( Orient Chemical Co., Ltd.) and Copy Blue PR (Clariant).

  The toner of the present invention is obtained by mixing the toner particles, the external additive containing the hydrophobic silica A and the hydrophobic silica B, and other optional components as necessary, using a Henschel mixer or the like. It can be produced by externally adding an external additive.

  The toner of the present invention may be used as a one-component developer, or may be used as a two-component developer by mixing with a carrier. When the toner of the present invention is used as a two-component developer, a resin-coated carrier having a resin coating layer can be suitably used as the carrier. The resin-coated carrier is obtained by coating the surface of a core material with a resin, and examples of the core material include magnetic powders such as iron powder, ferrite powder, and nickel powder. Examples of the resin that coats the carrier include a fluororesin, a vinyl resin, and a silicone resin.

The toner of the present invention containing an external additive containing hydrophobic silica A and hydrophobic silica B having different hydrophobicity and BET is in contact with the developer carrier and the developer carrier to regulate the toner layer thickness. The present invention is particularly preferably applied to an image forming method having a toner layer thickness regulating member. Further, the toner can exhibit particularly excellent effects when used in an image forming method having a process speed of 300 mm / sec or more.
When the toner layer thickness is regulated by coming into contact with the developer carrier, the toner is strongly pressed against the developer carrier by the toner layer thickness regulating member, and thus receives a very large mechanical load. In particular, when the process speed is 300 mm / sec or more, the contact portion is locally heated considerably by friction, so that the toner is rubbed at a high temperature and the inorganic fine particles adhering to the toner particle surface are embedded. As a result, the toner tends to deteriorate, and the density of the image tends to become thin.
On the other hand, in the toner of the present invention, hydrophobic silica A and hydrophobic silica B, which are external additives, are uniformly dispersed on the surface of the toner particles, and the effect of preventing deterioration of hydrophobic silica B having a relatively large particle diameter is exhibited. Because it is easy to be done, it is hard to deteriorate. Therefore, the toner of the present invention can correspond to a high-speed developing device having a toner layer thickness regulating member that regulates the toner layer thickness by contacting the developer carrying member.

  As the image forming method of the present invention, a normal method can be applied except that the toner of the present invention is used as a developer. For example, 1) a charging step in which a voltage is applied to the charging means to charge the object to be charged, 2) a step in which an electrostatic charge image is formed on the charged object to be charged, and 3) Development process for developing and forming a toner image on a charged body, 4) Transfer process for transferring a toner image on a charged body to a transfer material with or without an intermediate transfer body, and 5) Transfer Examples thereof include an image forming method including a fixing step of heat-fixing a toner image on a material.

In the image forming method of the present invention, in the 3) developing step, the charged body is opposed to a developer carrying body that carries the toner, and the developer carrying body includes a) a developing sleeve, and b) It is preferable to have an elastic blade that is located on the developing sleeve and forms a toner layer on the surface of the developing sleeve. More preferably, the process speed is 300 mm / s.
It is preferable that it is ec or more.
If there is an elastic blade for forming a toner layer on the developing sleeve, the toner is susceptible to mechanical impact and is likely to deteriorate. Therefore, suppression of deterioration, which is one of the characteristics of the toner of the present invention, is effectively expressed. To do. Further, when the process speed is 300 mm / sec or more, the toner is more easily deteriorated, and therefore, suppression of deterioration, which is one of the characteristics of the toner of the present invention, is more effectively expressed.

  Further, when the toner used in the image forming method of the present invention is a magnetic toner containing a magnetic substance (including the case where the colorant contained in the toner particles is a magnetic substance), the developer carrier A) a developing sleeve, b) an elastic blade for forming a magnetic toner layer on the surface of the developing sleeve, and c) a magnetic field generating means contained in the developing sleeve. preferable.

  Hereinafter, the present invention will be described more specifically by way of examples, but this does not limit the present invention in any way.

<Production example of hydrophobic silica 1>
Into a 2 liter autoclave with a stirrer, 50 g of untreated dry silica (BET specific surface area 200 m ² / g) was added and heated to 200 ° C. while fluidizing by stirring. While maintaining the fluidized state by stirring, the inside of the autoclave was replaced with nitrogen gas, the reactor was sealed, and hexamethyldisilazane was sprayed inside to hydrophobize the dry silica. This treatment was continued for 60 minutes.
The spray amount of hexamethyldisilazane and the reaction conditions were adjusted so that 24 parts by mass of hexamethyldisilazane (that is, 12 g) reacted with 100 parts by mass of the silica raw material. After completion of the reaction, the autoclave was depressurized and washed with a nitrogen gas stream to remove excess hexamethyldisilazane and by-products from the hydrophobic silica.

Furthermore, while stirring silica, dimethyl silicone oil (viscosity = 50 mm ² / s)
Was adjusted and sprayed so that the amount after treatment was 10 parts by mass, and stirring was continued for 30 minutes. Then, it heated up to 300 degreeC, stirring, and also stirred for 2 hours. Silica was taken out from the autoclave to obtain hydrophobic silica 1. The physical properties (specific surface area BET and degree of hydrophobicity) of the obtained hydrophobic silica 1 are shown in Table 1.

<Production example of hydrophobic silica 2-11>
As shown in Table 1, the hydrophobic silicas 2 to 11 are produced by the same procedure as that for the production of the hydrophobic silica 1 except that the specific surface area BET of the silica raw material and the kind and amount of the treatment agent are changed. did.

In Table 1 above,
(1) “Treatment amount” means the mass of various treatment agents treated with respect to 100 parts by mass of the silica raw material,
(2) BET (specific surface area) and hydrophobization degree are values measured and calculated using the method described above.

<Binder resin production example 1>
In a reaction vessel, 50 parts of a PO2 molar adduct of bisphenol A, 20 parts of an EO2 molar adduct of bisphenol A, 20 parts of terephthalic acid, 5 parts of fumaric acid, 5 parts of trimellitic anhydride, and 0.5 parts of dibutyltin oxide And heated to 220 ° C. to subject them to condensation polymerization to obtain a binder resin 1 which is a polyester resin. The acid value of this resin was 24 mgKOH / g, Tg was 59 ° C., and the THF insoluble content was 21% by mass.

<Binder resin production example 2>
In a four-necked flask, 300 parts by mass of xylene was added and heated to reflux. To this, a mixed liquid of 75 parts by mass of styrene, 25 parts by mass of acrylic acid-n-butyl and 2 parts by mass of di-tert-butyl peroxide was added dropwise over 5 hours to obtain a low molecular weight polymer (L-1). A solution was obtained.

  On the other hand, after putting 180 parts by mass of degassed water and 20 parts by mass of a 2% by weight aqueous solution of polyvinyl alcohol into another four-necked flask, 70 parts by mass of styrene, 30 parts by mass of acrylate-n-butyl, 0 divinylbenzene. 0.005 parts by mass and 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane (half-life 10 hours, temperature; 92 ° C.) 0.1 part by mass were added and stirred. A suspension was obtained. After sufficiently substituting the inside of the flask with nitrogen, the temperature was raised to 85 ° C. to polymerize and maintained for 24 hours, and then 0.1 part by mass of benzoyl peroxide (half-life 10 hours, temperature; 72 ° C.) was added. For an additional 12 hours. The high molecular weight polymer (H-1) was isolated by filtering the precipitate.

  25 parts by mass of the high molecular weight polymer (H-1) is added to 300 parts by mass of the homogeneous solution of the low molecular weight polymer (L-1), and after sufficiently mixing under reflux, the organic solvent is distilled off. Thus, a binder resin 2 was obtained. The obtained binder resin 2 had a main peak molecular weight = 12000, a subpeak molecular weight = 1.14 million, and an acid value = 0 mgKOH / g.

<Manufacture of toner particles 1>
Each component shown in Table 2 below was premixed using a Henschel mixer. The obtained mixture was melt-kneaded using a biaxial extruder heated to 110 ° C. and then cooled. The obtained kneaded material was finely pulverized with a hammer mill to obtain a finely pulverized toner.
The obtained finely pulverized product was coated with a mechanical pulverizer turbo mill (manufactured by Turbo Kogyo; coated with chromium alloy plating containing chromium carbide on the rotor and stator surfaces (plating thickness 150 μm, surface hardness HV1050)). Based on the conditions described in Table 3, the air temperature was adjusted and mechanically pulverized to finely pulverize. The finely pulverized product was classified and removed at the same time by a multi-division classifier (Elbow Jet Classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect to obtain raw material toner particles. The obtained raw toner particles had a weight average particle diameter (D ₄ ) measured by the Coulter Counter method of 6.4 μm, and the cumulative value of the number average distribution of toner particles of less than 4 μm was 24.2%. It was.

The obtained raw material toner particles were subjected to surface modification and fine powder removal using a surface modification apparatus shown in FIG. In the surface reforming apparatus used in this production example, 16 square disks were installed on the upper part of the dispersion rotor, the distance between the guide ring and the upper square disk of the dispersion rotor was 60 mm, and the distance between the dispersion rotor and the liner was 4 mm. It was. Further, the rotational peripheral speed of the dispersion rotor was set to 140 m / sec, and the blower air volume was set to 30 m ³ / min. Moreover, the input amount of the finely pulverized product was 300 kg, and the cycle time was 45 sec. The temperature of the refrigerant passed through the jacket was −15 ° C., and the cold air temperature T1 was −20 ° C. Furthermore, the particle ratio of 0.6 μm or more and less than 3 μm was set to a desired value by controlling the rotation speed of the classification rotor.

Through the above steps, the negatively chargeable toner particles 1 having a cumulative value of the number average distribution of the weight average particle diameter (D ₄ ) of 6.4 μm and less than 4 μm measured by the Coulter counter method of 18.1% are obtained. Obtained. The physical properties of the toner particles 1 measured with FPIA 2100, the methanol concentration value with respect to the transmittance of light having a wavelength of 780 nm, and the measured values with a scanning probe microscope are shown in Table 5, and the methanol dropping transmittance curve is shown in FIG. Negatively chargeable magnetic toner particles 1 having a weight average diameter (D4) of 6.4 μm were obtained.

<Manufacture of toner particles 2-11, 13 and 14>
In accordance with the conditions described in Table 3 below, toner particles 2 to 11, 13 and 14 were produced by the same procedure as the production of toner particles 1.
<Production of toner particles 12 and 15>
Using the binder resin 2 instead of the binder resin 1, toner particles 12 and 15 were produced in the same procedure as the production of the toner particle 1 according to the description in Table 3 below.

<Example 1: Production of toner 1>
As shown in Table 4, the toner particle 1 (100 parts by mass) in Table 3 is as shown in Table 1.
Toner 1 was obtained by adding hydrophobic silica 1 (1.35 parts by mass) and hydrophobic silica 8 (0.30 parts by mass) and externally adding with a Henschel mixer.

< Examples 2 to 7 and Reference Examples 8 to 10 : Production of Toners 2 to 10>
As described in Table 4, hydrophobic silicas A and B were added to toner particles 2 to 10 (100 parts by mass) in Table 3, and external addition was performed using a Henschel mixer to obtain toners 2 to 10. (Corresponding to Examples 2 to 7 and Reference Examples 8 to 10 , respectively).

<Comparative Examples 1-5>
As described in Table 4, silica A and B were added to toner particles 11 to 15 (100 parts by mass) in Table 3, and external addition was performed using a Henschel mixer to obtain toners 11 to 15 ( Corresponding to Comparative Examples 1 to 5, respectively).

<Test Example 1>
An image was formed using the toner 1 obtained in Example 1 under the following conditions.
(1) A printer in which the process speed of a commercially available LBP printer (Laser Jet 4300, manufactured by HP) was changed to 325 mm / sec (A4 size 55 sheets / min) was used as an image output tester.
(2) A horizontal line pattern with a printing rate of 2% was set to one sheet / job, and the machine was set to stop once between jobs and then start the next job.
(3) Images were formed under a low temperature and low humidity environment (15 ° C., 10% RH) and a high temperature and high humidity environment (32.5 ° C., 80% RH). (Hereinafter also referred to as “low temperature and low humidity environment test” and “high temperature and high humidity environment test”, respectively)
(4) A total of 20000 sheets (low-temperature, low-humidity environment test) or 20001 sheets (high-temperature, high-humidity environment test) were printed as 5,000 sheets per day.

<Image density evaluation>
For the image density, the reflection density of a solid black image of 5 mm square was measured using an SPI filter with a Macbeth densitometer (Macbeth Co., Ltd.), and this value was used as the image density.
In the low-temperature and low-humidity environment test, the image density at the initial stage, when printing 1001 sheets, when printing 5001 sheets (initially on the second day), when printing 10001 sheets (initially on the third day), and when printing 20000 sheets (end of durability on the fourth day) It was measured.
In the high-temperature and high-humidity environment test, at the initial stage, when printing 5001 sheets (initially on the second day), when printing 1,0001 sheets (initially on the third day), when printing 20000 sheets (end of durability on the fourth day), and when printing 20000 sheets (5 days The image density at the initial stage of the eye was measured.

<Fog evaluation>
Fog was measured as an indicator of toner durability.
In the low-temperature and low-humidity environment test, solid white images were formed on the transfer material during initial printing, 1001 printing, 5001 printing, 10001 printing, and 20000 printing. The reflection density of the transfer material before image formation and the reflection density of the transfer material after image formation were measured using a reflection densitometer (reflectometer model TC-6DS (manufactured by Tokyo Denshoku)).
The average value of the reflection density of the transfer material before the image formation was Dr, and the worst value of the reflection densities of the transfer material after the image formation was Ds. Ds-Dr was calculated | required and this was made into fogging amount. It shows that fog is suppressed, so that the numerical value of fog amount is small. Table 5 shows the fog amount as the “fogging worst value”.

<Cohesion degree before and after durability>
As an index indicating the toner fluidity, the degree of aggregation of the toner was measured using a powder tester P-100 (manufactured by Hosokawa Micron). Specifically, a sieve was set in the order of openings of 250 μm, 150 μm, and 75 μm from above on the vibration table, and 5 g of toner was gently placed on the upper sieve. The vibration table was vibrated with a vibration amplitude of 0.6 mm and a vibration time of 10 seconds. After the vibration was stopped, the mass of toner remaining on each of the sieves (upper, interrupted, and lower) was measured, and the values of a, b, and c were determined from the measured values according to the following formula. The sum of the values of a, b and c was defined as the degree of aggregation (%).
a = (amount of toner remaining on upper screen) ÷ 5 (g) × 100
b = (amount of toner remaining on the middle screen) ÷ 5 (g) × 100 × 0.6
c = (amount of toner remaining on the lower screen) ÷ 5 (g) × 100 × 0.2

  The degree of aggregation was measured with respect to the initial toner in the high-temperature and high-humidity environment test and the toner after 20,000 sheets of durability. The smaller the degree of aggregation, the better the toner is, and the smaller the degree of aggregation change between the initial stage and the endurance, the lower the deterioration.

<Image density difference>
In the high-temperature and high-humidity environment test, for the five solid black images at the initial stage, the 5001st sheet, the 10001st sheet, the 15001st sheet, and the 20001th sheet, the image density of the portion corresponding to the first round of the sleeve and the second round of the sleeve respectively. The image density of the part after the eye was measured. For each image, the difference between the image density of the portion corresponding to the first round of the sleeve and the image density of the portion after the second round of the sleeve was calculated, and the largest of the calculated differences was taken as the image density difference.

<Ghost evaluation>
5000 in a low-temperature, low-humidity environment (15 ° C., 10% RH) and a high-temperature, high-humidity environment (32.5 ° C., 80% RH) test (printing 20000 sheets of ordinary copier plain paper (75 g / m ² )) Each time a sheet was printed out, an image that was a solid black belt image for the first round of the sleeve and a halftone image was printed for the second and subsequent rounds of the sleeve. Schematic diagrams of the image pattern of the printed out image are shown in FIGS.
In the image pattern of FIG. 4, in the image for the second round of the sleeve, the density of the portion corresponding to the solid black belt image for the first round of the sleeve is lower than the density of the other portions. This phenomenon is called a negative ghost phenomenon.
In the image pattern of FIG. 5, on the contrary, in the image for the second round of the sleeve, the density of the portion corresponding to the solid black belt image for the first round of the sleeve is higher than the density of the other portions. This phenomenon is called a positive ghost phenomenon.

The reflection density of the portion corresponding to the solid black belt image corresponding to the first round of the sleeve (black printing portion) and the other portion (non-image portion) in the image corresponding to the second round of the sleeve is measured with a Macbeth densitometer. did. Using the measured reflection density after the black print portion and the reflection density after the non-image portion, the reflection density difference was calculated according to the following equation. (See Figure 4)
Reflection density difference = (<2> Reflection density after non-image area) − (<1> Reflection density after black printing area)

The reflection density difference was calculated for each of the printed images, and the worst value was obtained. From the determined worst value, the degree of ghost was evaluated by A to E according to the following criteria. As the reflection density difference is smaller, ghost is not generated and the level is better.
A: Less than 0.00-0.02 B: Less than 0.02-0.04 C: Less than 0.04-0.06 D: Less than 0.06-0.08 E: More than 0.08

<Evaluation of white spot>
In the high-temperature and high-humidity environment test, the solid, black images of the first, 5001, 10001, 150001, 20001 images were observed, and for each image, generated white spots (due to free silica) The number of possible silica marks was measured. The worst value of the measured number was calculated | required and it evaluated to AE from the calculated | required value according to the following references | standards.
A: No white spots occur B: About 1 to 3 white spots occur in a solid black image through endurance C: About 4 to 6 white spots occur in a solid black image through endurance D: Solid black through endurance 7-20 white spots occur in the image E: 21 or more white spots occur in the solid black image through endurance

<Test Examples 2 to 7 and Reference Test Examples 8 to 10 >
Instead of toner 1, toners 2-1 produced in Examples 2-7 and Reference Examples 8-10
A test was conducted in the same manner as in Test Example 1 except that 0 was used, and the various evaluations were performed.
<Comparative Test Examples 1-5>
A test was performed in the same manner as in Test Example 1 except that the toners 11 to 15 manufactured in Comparative Examples 1 to 5 were used instead of the toner 1, and the various evaluations were performed.

The evaluation results of Test Examples 1 to 7 and Reference Test Examples 8 to 10 and Comparative Test Examples 1 to 5 are shown in Table 5 (low temperature and low humidity environment test results) and Table 6 (high temperature and high humidity environment test results).

It is sectional drawing which shows roughly an example of the surface modification apparatus used in the surface modification process of this invention. It is the schematic which shows an example of the top view of the dispersion | distribution rotor shown in FIG. It is a figure which shows the methanol dripping transmittance | permeability curve of hydrophobic silica 1 and hydrophobic silica 8. FIG. It is explanatory drawing of the pattern for evaluating a negative ghost. It is explanatory drawing of the pattern for evaluating a positive ghost.

Explanation of symbols

31: Classification rotor 32: Fine powder recovery 33: Raw material supply port 34: Liner 35: Cold air introduction port 36: Dispersion rotor 37: Product discharge port 38: Discharge valve 39: Guide ring 40: Square disk 41: First space 42 : Second space

Claims (8)

A toner for electrostatic charge development containing toner particles containing at least a binder resin and a colorant, and an external additive containing at least hydrophobic silica A and hydrophobic silica B,
The toner particles have an average circularity of 0.930 to 0.970;
The hydrophobic silica A is a hydrophobized dry silica, which is treated with a silane coupling agent and then treated with silicone oil.
Hydrophobic silica B is a hydrophobized dry silica, which has been hydrophobized with alkoxysilanes,
A specific surface area BET _A of the hydrophobic silica A, the relationship between the specific surface area BET _B of the hydrophobic silica B is, 1.2 × a _{BET B ≦ BET A ≦ 5 ×} BET B, of the hydrophobic silica A The degree of hydrophobicity measured by methanol wettability (the value at a transmittance of 80% is the degree of hydrophobicity) WET _A is 77 % or more and less than 90%, and the hydrophobicity WET _B of the hydrophobic silica _B is An electrostatic charge developing toner, wherein the toner is 20% or more and less than 50%, and 25% <WET _A -WET _B <70%.   The total content of the hydrophobic silica A and the hydrophobic silica B is 0.5 to 5.0 parts by mass with respect to 100 parts by mass of the toner particles, and the hydrophobic silica A is contained. 2. The electrostatic charge developing toner according to claim 1, wherein the content of the hydrophobic silica B when the mass is 1 is 0.05 to 0.7. 3. The specific surface area BET _A hydrophobic silica A is a 80~250m ² / g, a specific surface area BET _B of the hydrophobic silica B is characterized by a 30~80m ² / g, claims The toner for electrostatic charge development according to 1 or 2. 1) a charging process in which a voltage is applied to the charging means to charge the object to be charged; 2) a process in which an electrostatic image is formed on the charged object to be charged; 3) a toner image obtained by developing the electrostatic image with toner. A developing process for forming the toner image on the charged body, 4) a transferring process for transferring the toner image on the charged body to the transfer material with or without the intermediate transfer body, and 5) a toner image on the transfer material. An image forming method including a fixing step of fixing by heating,
In the developing step, the member to be charged is opposed to a developer carrying member that carries the toner, and the developer carrying member is provided on the developing sleeve, a magnetic field generating means included in the developing sleeve, and the developing sleeve. An elastic blade for forming a toner layer on the surface of the developing sleeve, and the toner includes toner particles containing at least a binder resin and a colorant, and hydrophobic silica A having a different specific surface area BET And an external additive containing at least hydrophobic silica B,
The toner particles have an average circularity of 0.930 to 0.970;
The hydrophobic silica A is a hydrophobized dry silica, which is treated with a silane coupling agent and then treated with silicone oil.
Hydrophobic silica B is a hydrophobized dry silica, which has been hydrophobized with alkoxysilanes,
The relationship between the specific surface area BET _A hydrophobic silica A and a specific surface area BET _B of the hydrophobic silica B is a _{1.2 × BET B ≦ BET A ≦} 5 × BET B, hydrophobicity of the hydrophobic silica A Degree of WET _A is 77 % or more and less than 90%, Hydrophobization degree WET _B of the hydrophobic silica _B is 20% or more and less than 50%, and 25% <WET _A -WET _B <70% An image forming method, wherein the toner is an electrostatic charge developing toner.   5. The image forming method according to claim 4, wherein the toner particles have an average surface roughness measured by a scanning probe microscope of 5.0 nm or more and less than 45.0 nm.   The total content of the hydrophobic silica A and the hydrophobic silica B is 0.5 part by mass to 5.0 parts by mass with respect to 100 parts by mass of the toner particles, and the mass content of the hydrophobic silica A is 6. The image forming method according to claim 4, wherein the content mass of the hydrophobic silica B is 0.05 to 0.7. The specific surface area BET _A hydrophobic silica A is a 80~250m ² / g, a specific surface area BET _B of the hydrophobic silica B is characterized by a 30~80m ² / g, claims The image forming method according to any one of 4 to 6. The image forming method according to claim 4, wherein a process speed is 300 mm / sec or more.

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