JP2011253007A - Image forming method using two-component developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method for maintaining good charge rising property and a good charge level of a developer even when the developer is replenished with a different toner, and for preventing fog, toner scattering, sheet stains and the like in any environments including high temperature and high humidity or low temperature and low humidity conditions.SOLUTION: The image forming method comprises the steps of: forming an electrostatic latent image on an image carrier; forming a toner image by developing the electrostatic latent image with a two-component developer containing a carrier and a toner for electrostatic charge image development; and sequentially replenishing the developer with a replenishing toner. The method is characterized in that: the two-component developer shows fluidity of 100 sec/50 g or more when the toner concentration in the two-component developer is controlled to 6 wt.%; and the developer contains the following particles as an external additive for the toner that fills a developing cartridge and/or for the replenishing toner, the particles comprising positively charging metal oxide particles having a BET specific surface area of 100 m/g or more and two kinds of negatively charging metal oxide particles having a BET specific surface area of 110 m/g or less and having BET specific surface areas different from each other.

Description

  The present invention relates to an image forming method such as electrophotography and electrostatic photography.

In recent years, there has been a demand for a small amount of developer due to the need to increase the printing speed and reduce the size of the entire printer, and the amount of toner passing through a certain developer over a certain period of time has increased, so that the replenished toner can be charged. The time required to stand up is shorter than before. In order to solve this problem, there has been proposed a developer having good fluidity such that the fluidity when the toner concentration is 8 wt% is 50 seconds / 50 g or less (Patent Document 1). However, the relationship with the replenishing toner has not been studied, and when the flowability of the developer fluctuates due to an increase or decrease in the toner concentration, it has not been possible to cope with it sufficiently.

On the other hand, there has been proposed a method for improving transfer efficiency and cleaning properties by defining the particle sizes of the initial developer and the replenishment toner and the toner coverage of the initial developer (Patent Document 2). However, since the printing press is continuously used and the toner is replenished many times, it is difficult to maintain the printing quality with the characteristics of only the initial toner.
Thus, it has been desired to develop a toner that can print an image without any problem regardless of the type of the initial developer and the replenishing toner.

JP 2003-98718 A JP 2008-70765 A

  The present invention includes a step of forming an electrostatic latent image on an image carrier, a step of developing the electrostatic latent image with a two-component developer containing an electrostatic charge image developing toner and a carrier, and forming a toner image. An image forming method including a step of replenishing replenished toner, wherein a toner having a specific external additive and a developer having a specific fluidity are used to replenish the developer even if different toners are replenished. It is an object of the present invention to provide an image forming method that maintains good charge rising property and good charge amount level and does not cause fogging, toner scattering, paper stains, etc. in all environments including high temperature and high humidity and low temperature and low humidity.

  The present inventor has repeatedly studied to solve the above problems, and found that the above problems can be solved by using an image forming method using a toner having a specific external additive and a developer having a carrier. The present invention is based on this finding, and the gist of the present invention is as follows.

1. A step of forming an electrostatic latent image on the image carrier, a step of developing the electrostatic latent image with a two-component developer containing a toner for developing an electrostatic charge image and a carrier, and forming a toner image, and a replenishment toner sequentially An image forming method including a replenishing step,
When the toner concentration in the two-component developer is 6 wt%, the fluidity of the two-component developer is 100 seconds / 50 g or more, and as an external additive for the toner filled in the developing cartridge and / or the replenishment toner. A positively charged metal oxide particle having a BET specific surface area of 100 m ² / g or more and ^two negatively charged metal oxide particles having a BET specific surface area of 110 m ² / g or less and different BET specific surface areas. An image forming method.
2. 2. The positively charged metal oxide particles are contained in an amount of 0.2 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of toner and / or replenishment toner filled in the developing cartridge. Image forming method.
3. The image forming method as described in 1 or 2 above, wherein the two types of negatively charged metal oxide particles have a BET specific surface area of 25 m ² / g or more.
4). 4. The image forming method as described in any one of 1 to 3 above, wherein the negatively charged metal oxide particles and / or the positively charged metal particles are given hydrophobicity by surface treatment.
5). 5. The image forming method as described in any one of 1 to 4 above, wherein the positively charged metal oxide particles are silica particles, and the two kinds of negatively charged metal oxide particles are titanium oxide particles and silica particles.
6). 6. The image forming method according to any one of 1 to 5, wherein the negatively charged metal oxide particles include three types of particles having a BET specific surface area of 110 m ² / g or less and different BET specific surface areas.
7). 7. The image forming method as described in any one of 1 to 6 above, wherein the volume median diameter of the toner filled in the developing cartridge and the replenishing toner is 4 μm or more and 8 μm or less.
8). 8. The image forming method as described in any one of 1 to 7 above, wherein an average circularity of the toner filled in the developing cartridge and the replenishing toner is 0.91 or more and 0.99 or less.
9. 9. The image forming method as described in any one of 1 to 8 above, wherein the carrier has a BET specific surface area of 0.1 m ² / g or more and 1 m ² / g or less.
10. 10. The image forming method as described in any one of 1 to 9 above, wherein the fluidity of the carrier is 20 seconds / 50 g or more and 50 seconds / 50 g or less.

The image forming method of the present invention comprises a step of forming an electrostatic latent image on an image carrier, and developing the electrostatic latent image with a two-component developer containing an electrostatic charge image developing toner and a carrier to form a toner image. A step of forming, and a step of replenishing replenishment toner sequentially. The two-component developer is filled in a developing cartridge (hereinafter sometimes referred to as a developing tank) of the image forming apparatus.
In the two-component developing type developing cartridge, the toner carried on the carrier surface leaves the carrier surface by the developing electric field and moves toward the photosensitive member, and then the replenishing toner is carried on the carrier surface. The replacement is repeated. In order to obtain a stable image with high image quality without causing scattering or paper contamination over a long period of time, it is necessary to keep the charge amount of the toner in the developer appropriate. On the other hand, as the machine becomes smaller and faster, there is a demand for a small amount of developer, and the toner is carried on the carrier, charged, and the time until development is shortened. It is difficult to smoothly charge, and there is a need for technical development to deal with this problem.

Toner replacement is largely related to the fluidity of the developer. If the fluidity is too good, the amount of toner that cannot be sufficiently frictionally charged with the carrier increases, which may cause in-machine scattering or paper contamination. This fluidity varies depending on the shape of the toner, such as particle diameter and circularity, and the type and amount of the external additive to be added, but varies depending on the toner concentration and the charging characteristics of the toner. For example, when the toner concentration of the developer is constant, in order to obtain a stable image with high image quality without causing scattering or paper smearing, the toner needs a certain amount of charge, but this charge amount is It also affects the fluidity of the developer.
The shape of the toner varies depending on the manufacturing method, and there is a tendency to reduce the diameter from the trend of high image quality, but the circularity has various sizes that are optimal for each machine from the viewpoint of cleaning properties and transferability, No matter what circularity toner is replenished, good charge rise and charge amount level are maintained, and fog, toner scattering, paper stains, etc. do not occur in all environments including high temperature high humidity, low temperature low humidity, It is important to develop toners that are compatible with various toners.
In the present invention, even when a toner whose circularity is different from the toner constituting the two-component developer is added to the developer by replenishment, the fluidity of the toner having a specific external additive is controlled within a certain range. It has been found that the toner carried on the carrier can be smoothly replaced without being contaminated with toner, and a stable image with high image quality can be obtained.

In the two-component developing type developing cartridge (developing tank), toner and carrier are mixed and exist. The toner is consumed in the image formation, and the replenishment toner is replenished. However, the replenishment toner is improved by the repulsive force generated due to charging between the developer in the cartridge and the toner and the difference in charge, and the fluidity of the developer. May not be compatible with developer. If there is toner that does not fit well with the developer, density reduction during printing, paper smearing, in-machine scattering, etc. may occur, and continuous printing using replenishing toner may not be possible.
The fluidity when the toner concentration of the two-component developer of the present invention is 6 wt% is essential to be 100 seconds / 50 g or more. Preferably it is 105 seconds / 50 g or more, more preferably 110 seconds /
It is 50 g or more.
Moreover, an upper limit is not specifically limited, In the following measuring method, the value from which all a developer does not flow is also contained. The fluidity of the present invention is represented by the time required for 50 g of a two-component developer having a toner concentration of 6 wt% measured by the method defined in JIS-Z-2504 to be discharged from the measuring funnel.
By using the two-component developer having the specific fluidity of the present invention, the toner repulsive force of the developer is reduced, and it is possible to appropriately charge even if toners having different properties such as different toner circularity are replenished. I can do it. If the fluidity of the two-component developer is too small, the toner in the developer is highly charged, the repulsive force of the developer and the toner for replenishment is too strong, the carrier and the toner do not mix well, and paper stains and scattering occur. There is a case.

The toner of the two-component developer and the replenishment toner of the present invention are composed of toner base particles and an external additive attached or fixed to the surface of the toner base particles. The additive must contain positively charged metal oxide particles having a BET specific surface area of 100 m ² / g or more and ^two negatively charged metal oxide particles having a BET specific surface area of 110 m ² / g or less.
In the two-component developer, the toner and the carrier are charged by rubbing against each other, and the charged toner is developed onto a photoreceptor or the like. For this reason, the toner and the carrier have opposite polarities, and the toner and the carrier are liable to be excessively separated from each other, and the entire toner may not be uniformly charged due to the contamination of the carrier and the replacement of the toner on the carrier surface. In the present invention, when the carrier is positively charged and the toner and the replenishing toner are negatively charged, the positively charged metal oxide serves as a cushion between the toner and the carrier by externally adding a metal oxide that is positively charged. The charged toner is moderately easily separated from the carrier and has a different circularity from that of the toner constituting the developer, so that the toner can be smoothly supplied even when the developer is charged with different charge and fluidity. It is estimated that can be replaced.

When the BET specific surface area of the positively charged metal oxide particles used in the present invention is D1 (m ² / g), B
ET specific surface area D1 (m ² / g) is 100 m ² / g or more is essential, is preferably 110m ² / g or more. Further, it is preferably 135 m ² / g or less, and particularly preferably 130 m ² / g or less. If the BET specific surface area is too large, the metal oxide particles are likely to aggregate and may not be uniformly externally added. If the BET specific surface area is too small, the metal oxide particles may be detached from the toner and contaminate the carrier.

The metal oxide particles having a BET specific surface area of D1 (m ² / g) are not particularly limited, but include inorganic particles such as aluminum oxide (alumina), zinc oxide, tin oxide, barium titanate, strontium titanate, and the like. Silica is particularly preferable for obtaining the effects of the present invention.
Further, the metal oxide particles having a BET specific surface area of D1 (m ² / g) may be subjected to a surface treatment, and it is preferable to perform a hydrophobization treatment because of preservation and environmental stability. Examples of the hydrophobizing agent used in the hydrophobizing treatment include those used as usual surface treating agents such as silane coupling agents such as hexamethyldisilazane, titanate coupling agents, silicone oil, and silicone varnish. . Furthermore, a fluorine-based silane coupling agent, a fluorine-based silicone oil, a coupling agent having an amino group or a quaternary ammonium base, a modified silicone oil, or the like can also be used. These hydrophobizing agents are preferably used in a state dissolved in a solvent such as an organic solvent.

The average primary diameter of the metal oxide particles having a BET specific surface area D1 (m ² / g) is not particularly limited, but is preferably 5 nm or more, and more preferably 10 nm or more. Further, it is preferably 25 nm or less, and more preferably 20 nm or less. If the average primary diameter is too large, it tends to be excessively liberated from the mother particles and contaminates the carrier, and if it is too small, the transfer efficiency tends to decrease.
The average primary diameter of the present invention is measured by performing image analysis of SEM photographs. Specifically, using a scanning electron microscope S4500 manufactured by Hitachi, Ltd., after taking an appropriate number of photographs of the particles magnified 30000 times, 100 particles were randomly selected and image analysis made by Mitani Corporation These equivalent circle diameters were measured by software WinROOF, and the average value was defined as the average primary particle diameter.

The metal oxide particles having a BET specific surface area of D1 (m ² / g) are preferably 0.5 parts by mass or less and 100 parts by mass or less with respect to 100 parts by mass of the toner base particles. Further preferred. Moreover, 0.2 mass part or more is preferable and 0.25 mass part or more is more preferable.
If the amount added is too large, the charge may be low and paper fog may be high.If the amount is too small, it becomes difficult to separate the toner and the carrier, and the contamination of the carrier and the replacement of the toner on the carrier surface are delayed. In some cases, the entire toner is not uniformly charged, and paper stains may occur.

The BET specific surface areas of the two types of negatively charged metal oxide particles having different BET specific surface areas of the present invention are D2 and D3 (m ² / g), respectively. It is essential that D2 and D3 each be 110 m ² / g or less. D2 and D3 are each preferably 25 m ² / g or more. Furthermore, it is preferable that D1, D2, and D3 have different values.

The negatively charged metal oxide particles having a BET specific surface area of D2 (m ² / g) are not particularly limited, and are not particularly limited as long as the BET specific surface area is satisfied. Aluminum oxide (alumina), zinc oxide, tin oxide Inorganic particles such as barium titanate and strontium titanate are exemplified, and titanium oxide particles are particularly preferable for obtaining the effects of the present invention.

When titanium oxide particles are used as the negatively charged metal oxide particles having a BET specific surface area of D2 (m ² / g) according to the present invention, the surface treatment is performed with an organic compound, an inorganic compound, or both, although there is no particular limitation. Those are preferable for obtaining the effects of the present invention.
The inorganic compound used for the surface treatment and the surface treatment method are not particularly limited, but inorganic compounds such as aluminum, silicon, and zinc can be surface-treated by a conventional method such as a wet method and a dry method. An organic compound such as a fatty acid metal salt can be surface-treated by a conventional method such as a wet method or a dry method. Moreover, you may perform a hydrophobic process.

Metal oxide particles having a BET specific surface area D2 (m ² / g) are negatively charged. When the negatively charged metal oxide particles flow on the toner, there is a tendency to obtain more negative chargeability of the toner.
BET specific surface area D2 (m ² / g), which is essential or less 110m ² / g, more preferably not more than 105m ² / g. It is also preferably at 25m ² / g or more and is preferably 50 m ² / g or more, more preferably 80 m ² / g or more, particularly preferably 85 m ² / g or more. If D2 (m ² / g) is too small, it may be excessively liberated from the mother particles and contaminate the carrier, and if it is too large, transfer efficiency may be reduced and cleaning failure may occur.

The metal oxide particles having a BET specific surface area D2 (m ² / g) of the present invention are preferably externally added in an amount of 1.5 parts by mass or less, based on 100 parts by mass of the toner base particles, and 1.2 parts by mass. More preferably, it is as follows. Moreover, 0.3 mass part or more is preferable and 0.6 mass part or more is especially preferable.
If there are too many metal oxide particles having a BET specific surface area D2 (m ² / g), filming on the organic photoreceptor drum may occur. This is because when the metal oxide particles having a BET specific surface area of D2 (m ² / g) are scraped off by the cleaning part of the organic photosensitive drum and removed to the outside of the system, they adhere strongly to the surface of the organic photosensitive drum. It is presumed that the average particle size is caused due to innumerable scratches formed on the surface of the organic photosensitive drum. On the other hand, if the amount is too small, it may be difficult to obtain the effects of the present invention.

The average primary diameter of the metal oxide particles having a BET specific surface area D2 (m ² / g) is not particularly limited, but is preferably 5 nm or more, and more preferably 10 nm or more. Further, it is preferably 25 nm or less, and more preferably 20 nm or less. If the average primary diameter is too large, it tends to be excessively liberated from the mother particles and contaminates the carrier, and if it is too small, the transfer efficiency tends to decrease.

When titanium oxide particles are used as the metal oxide particles having a BET specific surface area of D2 (m ² / g), the electric resistance value is preferably 1 × 10 ⁺¹⁰ Ω · cm or less, preferably 1 × 10 ⁺⁹ Ω · cm. More preferably, it is not more than cm. Further, it is preferably 1 × 10 ⁺³ Ω · cm or more, and more preferably 1 × 10 ⁺⁶ Ω · cm or more.
If the electrical resistance is too high, the toner charge amount may be excessively high or low, and may cause fogging, local image density fluctuations in solid images, etc. An external additive or the like may cause a problem in charging control of the printing system and adversely affect the printed image. For example, if a small amount of external additive that could not be removed from the system by the cleaning unit of the organic photosensitive drum adheres to a contact-type charging roller that charges the organic photosensitive drum, charging is applied to the organic photosensitive drum. May cause image defects due to charging failure on the drum surface. On the other hand, if the electric resistance is too small, the toner particles in the developing tank are leaked to lower the charge, so that image defects such as fog may occur.

The metal oxide particles having a BET specific surface area D3 (m ² / g), which is one of two types of negatively charged metal oxide particles having different BET specific surface areas according to the present invention, are intended to improve toner transfer efficiency and cleaning properties. Use.
The metal oxide particles having a BET specific surface area D3 (m ² / g) of the present invention are not particularly limited, but include inorganic particles such as aluminum oxide (alumina), zinc oxide, tin oxide, barium titanate, strontium titanate, and the like. In particular, silica particles are preferable for obtaining the effects of the present invention. Further, the metal oxide particles having a BET specific surface area of D3 (m ² / g) may be subjected to a surface treatment, and it is preferable to carry out a hydrophobization treatment for preservation and environmental stability. Examples of the hydrophobizing agent used in the hydrophobizing treatment include those used as usual surface treating agents such as silane coupling agents such as hexamethyldisilazane, titanate coupling agents, silicone oil, and silicone varnish. . Furthermore, a fluorine-based silane coupling agent, a fluorine-based silicone oil, a coupling agent having an amino group or a quaternary ammonium base, a modified silicone oil, or the like can also be used. These hydrophobizing agents are preferably used in a state dissolved in a solvent such as an organic solvent.

The metal oxide particles having a BET specific surface area of D3 (m ² / g) are not particularly limited as long as they satisfy the relationship of the BET specific surface area, but are preferably 25 m ² / g or more, and 35 m ² / g or more. More preferably, it is more preferably 38 m ² / g or more. Further, it is essential that it is 110 m ² / g or less, more preferably 80 m ² / g or less, further preferably 55 ² / g or less, and particularly preferably 50 m ² / g or less. . If the BET specific surface area D3 (m ² / g) is too small, it may be excessively liberated from the mother particles, contaminating the carrier, or the toner fluidity may not be ensured, and supply failure may occur. In some cases, the toner is excessively charged.

The average primary diameter of the metal oxide particles having a BET specific surface area D3 (m ² / g) of the present invention is not particularly limited, but is preferably 20 nm or more, and more preferably 25 nm or more. Further, it is preferably 55 nm or less, and more preferably 50 nm or less. If the average primary diameter is too large, it tends to be excessively liberated from the mother particles and contaminates the carrier, and if it is too small, the toner tends to be charged excessively.

The metal oxide particles having a BET specific surface area D3 (m ² / g) of the present invention are negatively charged. When the negatively charged metal oxide particles flow on the toner, there is a tendency that the toner can be more negatively charged and can be charged.

The metal oxide particles having a BET specific surface area D3 (m ² / g) of the present invention are preferably externally added in an amount of 1.5 parts by mass or less, based on 100 parts by mass of the toner base particles, and 1.2 parts by mass. More preferably, it is as follows. Moreover, 0.5 mass part or more is preferable and 0.6 mass part or more is especially preferable. When there are too many metal oxide particles having a BET specific surface area D3 (m ² / g), the charge becomes excessively high, which may cause a decrease in density and paper stains. When the amount is too small, the fluidity of the toner decreases. There is.

The two types of negatively charged metal oxide particles having a BET specific surface area of D2 (m ² / g) and D3 (m ² / g) according to the present invention have different BET specific surface area values, and further D3 <D2. It is preferable that the two-component developer maintains appropriate fluidity and tends to prevent paper contamination and toner scattering during printing.

In the present invention, the negatively charged metal oxide particles having a BET specific surface area of 110 m ² / g or less may include three kinds of particles having different BET specific surface areas.
In addition to the negatively charged metal oxide particles of D2 and D3 (m ² / g) as described above, the BET specific surface area of the third negatively charged metal oxide particle is D4 (m ² / g). Preferably satisfies the relationship of the formula (1).
25 m ² / g ≦ D4 <D3 <D2 ≦ 110 m ² / g (1)
By including these negatively charged metal oxide particles, there are cases where the transfer efficiency and cleaning performance of the toner can be further improved.

The metal oxide particles having a BET specific surface area D4 (m ² / g) of the present invention are not particularly limited, and examples thereof include inorganic particles such as aluminum oxide, zinc oxide, tin oxide, barium titanate, and strontium titanate. Silica particles are preferred for obtaining the effects of the present invention.
Further, the metal oxide particles having a BET specific surface area of D4 (m ² / g) may be subjected to a surface treatment, and it is preferable to perform a hydrophobization treatment because of preservation and environmental stability. Examples of the hydrophobizing agent used in the hydrophobizing treatment include those used as usual surface treating agents such as silane coupling agents such as hexamethyldisilazane, titanate coupling agents, silicone oil, and silicone varnish. . Furthermore, a fluorine-based silane coupling agent, a fluorine-based silicone oil, a coupling agent having an amino group or a quaternary ammonium base, a modified silicone oil, or the like can also be used. These hydrophobizing agents are preferably used in a state dissolved in a solvent such as an organic solvent.

Metal oxide particles having a BET specific surface area of the present invention D4 (m ² / g) is not particularly limited if they meet the relationship of formula (1), is preferably 25 m ² / g or more, 30 m ² / More preferably, it is g or more. Further, it is preferably 110 m ² / g or less, more preferably 80 m ² / g or less, further preferably 45 m ² / g or less, and particularly preferably 40 m ² / g or less. If the BET specific surface area D4 (m ² / g) is too small, it may be excessively liberated from the mother particles, contaminating the carrier, or the toner fluidity may not be ensured, and supply failure may occur. In some cases, the transfer efficiency is lowered and cleaning failure occurs.

The average primary diameter of the metal oxide particles having a BET specific surface area D4 (m ² / g) of the present invention is not particularly limited, but is preferably 70 nm or more, and more preferably 80 nm or more. Further, it is preferably 200 nm or less, and more preferably 160 nm or less. If the average primary diameter is too large, it tends to be excessively liberated from the mother particles and contaminates the carrier, and if it is too small, the transfer efficiency tends to decrease.

The metal oxide particles having a BET specific surface area D4 (m ² / g) of the present invention are preferably negatively charged. When the negatively charged metal oxide particles flow on the toner, there is a tendency that the toner can be more negatively charged and can be charged.

The metal oxide particles having a BET specific surface area D4 (m ² / g) of the present invention are preferably externally added in an amount of 3 parts by mass or less, based on 100 parts by mass of the toner base particles, and 2 parts by mass or less. Is more preferable, and it is particularly preferably 1 part by mass or less. Moreover, 0.5 mass part or more is preferable and 0.7 mass part or more is further more preferable. If there are too many metal oxide particles having a BET specific surface area D4 (m ² / g), the charge will be excessively high, resulting in a decrease in density and paper stains. May decrease.

The metal oxide particles having BET specific surface areas D1, D3, and D4 (m ² / g) used in the present invention are externally added in an amount of 5 parts by mass or less based on 100 parts by mass of the toner base particles. Preferably, it is 3 parts by mass or less. Moreover, 1 mass part or more is preferable and 1.4 mass part or more is further more preferable. If the amount of external additive is too large, the amount of free metal oxide particles that cannot adhere to the surface of the mother particles will increase, resulting in image defects such as fogging and paper stains due to toner charge rise failure and charge amount distribution enlargement. There is. On the other hand, if the amount is too small, sufficient toner fluidity cannot be secured and image defects such as poor solid uniformity may occur.
External addition amount (M3) of metal oxide particles having a BET specific surface area D3 (m ² / g) and external addition amounts of metal oxide particles having a BET specific surface area D4 (m ² / g) with respect to 100 parts by mass of the toner base particles. (M4) has a mass ratio M3 / M4 of preferably 2 or more, and more preferably 2.5 or more. M
If 3 / M4 is too small, transfer efficiency tends to decrease and cleaning failure tends to occur.

The fluidity of the carrier used in the two-component developer of the present invention is preferably 20 seconds / 50 g or more, and more preferably 25 seconds / 50 g or more. Further, it is preferably 50 seconds / 50 g or less, more preferably 45 seconds / 50 g or less.
When the fluidity of the carrier is within this range, the fluidity of the developer may be in a specific range and the effects of the present invention may be easily obtained.

The BET specific surface area of the carrier of the present invention is preferably 0.08 m ² / g or more, and more preferably 0.1 m ² / g or more. Further, it is preferably 1 m ² / g or less, and more preferably 0.9 m ² / g or less. If the specific surface area of the carrier is too small, the uniformity of the solid may deteriorate, and if it is too large, the carrier may scatter from the cartridge (developing tank). Further, the volume median diameter of the carrier is preferably 20 μm or more and 200 μm or less.

The toner of the present invention preferably contains the metal oxide particles having the BET specific surface areas D1, D2, D3, and D4 (m ² / g) on the surface of the toner base particles, but the effect of the present invention is not impaired. In the range, it may be used in combination with other particles known as external additives to adhere to or adhere to the surface of the toner base particles.

  Examples of other particles include inorganic particles such as silica, aluminum oxide (alumina), zinc oxide, tin oxide, barium titanate, strontium titanate; organic acid salt particles such as zinc stearate and calcium stearate; methacrylate ester Examples thereof include organic resin particles such as polymer particles, acrylic acid ester polymer particles, styrene-methacrylic acid ester copolymer particles, and styrene-acrylic acid ester copolymer particles.

The blending ratio of the metal oxide particles of the BET specific surface areas D1, D2, D3, and D4 (m ² / g) of the present invention to “other particles” is not particularly limited, and the BET specific surface areas D1, D2, and D3 are not particularly limited. , D4 (m ² / g) metal oxide particles and the total amount of the external additive composed of “other particles” is not particularly limited, but the total amount of the external additive is 100 parts by weight of the toner base particles. The amount used is preferably 1 part by mass or more, more preferably 1.2 parts by mass or more, and particularly preferably 1.3 parts by mass or more. Moreover, 5 mass parts or less are preferable, 4 mass parts or less are more preferable, and 3 mass parts or less are especially preferable. If the amount used is too small, the fluidity may be deteriorated or the charge amount may not be controlled. On the other hand, if the amount used is too large, the free additive that has not adhered can contaminate the components in the cartridge. However, this may cause image defects.

The order of attaching or fixing the external additive used in the present invention to the surface of the toner base particles is not particularly limited, but from the viewpoint of the working mechanism of the present invention, the “other particles” are the aforementioned BET specific surface areas. It is preferable to add it simultaneously with or after the metal oxide particles of D1, D2, D3, and D4 (m ² / g).

In the present invention, the method of adhering or fixing the metal oxide particles having the BET specific surface areas D1, D2, D3, and D4 (m ² / g) and / or “other particles” to the surface of the toner base particles is as follows. There is no particular limitation, and a mixer generally used for toner production can be used. Specifically, it is performed by uniformly stirring and mixing with a mixer such as a Henschel mixer, a V-type blender, a Redige mixer, or a Q-mixer.

  The volume median diameter of the toner of the present invention is preferably 4 μm or more, and more preferably 5 μm or more. Moreover, it is preferable that it is 8 micrometers or less, and it is more preferable that it is 7 micrometers or less. If the volume median diameter is too large, the charge amount per unit weight tends to decrease, and there is a possibility that fogging and toner scattering may occur, while if it is too small, the charge amount per unit weight will increase. In some cases, it tends to be excessive, and problems such as an extreme decrease in image density may occur. The volume median diameter is measured by the method described in the examples.

By using the image forming method of the present invention, it is possible to prevent the occurrence of image defects and the like even when toners having different average circularity are used. The average circularity of the toner base particles used in the present invention is preferably 0.91 or more, and more preferably 0.92 or more. Moreover, it is preferable that it is 0.99 or less, and it is more preferable that it is 0.985 or less.
If the degree of circularity is too large, slipping may easily occur in the cleaning unit, resulting in an image defect. On the other hand, when it is too small, when the external additive rolls on the surface of the mother particle by stirring due to printing durability, it may fall into the depression of the mother particle, and the effect of the present invention may not be maintained until the end. The circularity of the toner base particles of the present invention is measured by the method described in the examples.

The method for producing the toner used in the present invention is not particularly limited, and a conventionally used method such as a pulverization method, a wet method, a method of spheroidizing the toner by a mechanical impact force, heat treatment or the like can be used.
Examples of the wet method include a suspension polymerization method, an emulsion polymerization aggregation method, a dissolution suspension method, and an ester extension method.

As a method for producing a toner obtained by the pulverization method, a binder resin, a colorant and, if necessary, other components are weighed and mixed and mixed. Examples of the mixing apparatus include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, and a Nauter mixer.
Next, the blended and mixed toner raw materials are melt-kneaded to melt the resins and disperse the colorant and the like therein. In the melt-kneading step, for example, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used. For the kneading machine, a single-screw or twin-screw extruder is used. For example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type twin screw extruder manufactured by Toshiba Machine Co., Ltd., twin screw extruder manufactured by K.C.K. , Bus Co., Ltd. co-kneader. Furthermore, the colored resin composition obtained by melt-kneading the toner raw material is rolled by a two-roll roll after melt-kneading, and then cooled through a cooling step of cooling by water cooling or the like.
The cooled product of the colored resin composition obtained above is then pulverized to a desired particle size in a pulverization step. In the pulverization step, first, coarse pulverization is performed with a crusher, a hammer mill, a feather mill or the like, and further, pulverization is performed with a kryptron system manufactured by Kawasaki Heavy Industries, Ltd., a super rotor manufactured by Nisshin Engineering Co., Ltd. or the like. After that, if necessary, the particles are classified using a classifier such as an inertia classification type elbow jet (manufactured by Nippon Steel Mining Co., Ltd.) or a centrifugal classification type turboplex (manufactured by Hosokawa Micron Co., Ltd.). obtain. Further, the toner may be spheroidized using a conventionally used method such as mechanical impact force or heat treatment.

  In the present invention, the method for producing the suspension polymerization toner includes a colorant, a polymerization initiator, and, if necessary, additives such as a wax, a polar resin, a charge control agent and a crosslinking agent in the monomer of the binder resin. Is added to prepare a monomer composition which is uniformly dissolved or dispersed. This monomer composition is dispersed in an aqueous medium containing a dispersion stabilizer and the like. Preferably, granulation is performed by adjusting the stirring speed and time so that the droplets of the monomer composition have a desired toner particle size. Thereafter, polymerization is performed by stirring to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. These are collected by washing and filtration, and dried to obtain toner mother particles. Further, if necessary, toner can be obtained by external addition or the like.

  As a production method of the emulsion polymerization aggregation method, polymer primary particles of a binder resin monomer obtained by emulsion polymerization, a colorant dispersion, a wax dispersion, etc. are prepared, and these are dispersed in an aqueous medium. By carrying out heating or the like, it undergoes an agglomeration step and an aging step. These are collected by washing and filtration, and dried to obtain toner mother particles. Further, if necessary, toner can be obtained by external addition or the like.

  The toner used in the present invention contains at least a binder resin and a colorant, and optionally contains a charge control agent, wax, other additives, and the like.

  In the present invention, as the binder resin contained in the toner, resins conventionally used as the binder resin for toner can be appropriately used. For example, as a monomer, a polymerizable monomer having an acidic group (hereinafter sometimes simply referred to as an acidic monomer), a polymerizable monomer having a basic group (hereinafter simply referred to as a basic monomer) A polymerizable monomer having no acidic group or basic group (hereinafter, also referred to as other monomer) may be used. it can.

  When a toner is produced using an emulsion polymerization aggregation method, in the emulsion polymerization step, a polymerizable monomer is usually polymerized in an aqueous medium in the presence of an emulsifier. In supplying the monomer, each monomer may be added separately, or a plurality of types of monomers may be mixed in advance and added simultaneously. The monomer may be added as it is, or may be added as an emulsion mixed and adjusted in advance with water or an emulsifier.

As the acidic monomer, a polymerizable monomer having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, cinnamic acid, a polymerizable monomer having a sulfonic acid group such as sulfonated styrene, Examples thereof include polymerizable monomers having a sulfonamide group such as vinylbenzenesulfonamide. Examples of the basic monomer include aromatic vinyl compounds having an amino group such as aminostyrene, nitrogen-containing heterocyclic-containing polymerizable monomers such as vinylpyridine and vinylpyrrolidone, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, etc. And (meth) acrylic acid ester having an amino group. These acidic monomers and basic monomers may be used singly or as a mixture of a plurality of types, and may exist as a salt with a counter ion. Among these, it is preferable to use an acidic monomer, more preferably acrylic acid and / or methacrylic acid.

  The total amount of the acidic monomer and the basic monomer in 100 parts by mass of the total polymerizable monomers constituting the binder resin is preferably 0.05 parts by mass or more, more preferably 0.5 parts by mass. More preferably, it is 1 part by mass or more, preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

  Examples of other polymerizable monomers include styrenes such as styrene, methylstyrene, chlorostyrene, dichlorostyrene, p-tert-butylstyrene, pn-butylstyrene, and pn-nonylstyrene, methyl acrylate, Acrylic esters such as ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n methacrylate -Methacrylic acid esters such as butyl, isobutyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, acrylamide, N-propylacrylamide, N, N-dimethylacrylamide, N, N-dipropylacrylic De, N, N-dibutyl acrylamide, and the like, the polymerizable monomer may be used singly, or may be used in combination.

  Furthermore, when the binder resin is a cross-linked resin, a polyfunctional monomer having radical polymerizability is used together with the above polymerizable monomer, for example, divinylbenzene, hexanediol diacrylate, ethylene glycol dimethacrylate, Examples include diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, and diallyl phthalate. It is also possible to use a polymerizable monomer having a reactive group in a pendant group, such as glycidyl methacrylate, methylol acrylamide, acrolein and the like. Among these, radically polymerizable bifunctional polymerizable monomers are preferable, and divinylbenzene and hexanediol diacrylate are particularly preferable. These polyfunctional polymerizable monomers may be used alone or as a mixture of plural kinds.

  When the binder resin is polymerized by emulsion polymerization, a known surfactant can be used as an emulsifier. As the surfactant, one or more surfactants selected from cationic surfactants, anionic surfactants, and nonionic surfactants can be used in combination.

Examples of the cationic surfactant include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl ammonium bromide, and examples of the anionic surfactant include And fatty acid soap such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate and the like. Nonionic surfactants include, for example, polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, monodecanoyl sucrose, etc. Is mentioned.

  The amount of the emulsifier of the present invention is preferably 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer. In addition, these emulsifiers can be used as protective colloids, for example, one or more of partially or completely saponified polyvinyl alcohols such as polyvinyl alcohol and cellulose derivatives such as hydroxyethyl cellulose.

  The volume average particle diameter of the polymer primary particles obtained by emulsion polymerization is usually 0.02 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, and usually 3 μm or less, preferably 2 μm or less, more preferably. Is desirably 1 μm or less. When the particle size is smaller than the above range, it may be difficult to control the aggregation rate in the aggregation process. When the particle size is larger than the above range, the particle size of the toner particles obtained by aggregation tends to be large, It may be difficult to obtain a toner having a particle size of

  In this invention, a well-known polymerization initiator can be used as needed, A polymerization initiator can be used 1 type or in combination of 2 or more types. For example, persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate, and the like, and redox initiators combining these persulfates as a component with a reducing agent such as acidic sodium sulfite, hydrogen peroxide, 4,4 Water-soluble polymerization initiators such as' -azobiscyanovaleric acid, t-butyl hydroperoxide, cumene hydropeoxide, etc., and these water-soluble polymerization initiators as a component combined with a reducing agent such as ferrous salt Redox initiator systems, benzoyl peroxide, 2,2′-azobis-isobutyronitrile, and the like are used. These polymerization initiators may be added to the polymerization system before, simultaneously with the addition of the monomer, or after the addition, and these addition methods may be combined as necessary.

  In the present invention, a known chain transfer agent can be used as necessary, and specific examples include t-dodecyl mercaptan, 2-mercaptoethanol, diisopropyl xanthogen, carbon tetrachloride, trichlorobromomethane and the like. It is done. The chain transfer agent may be used alone or in combination of two or more, and is used in an amount of 0 to 5% by weight based on the polymerizable monomer.

Moreover, in this invention, a well-known suspension stabilizer can be used as needed. Specific examples of the suspension stabilizer include calcium phosphate, magnesium phosphate calcium hydroxide, magnesium hydroxide and the like. These may be used alone or in combination of two or more, and may be used in an amount of 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer.
Both the polymerization initiator and the suspension stabilizer may be added to the polymerization system at any time before, simultaneously with, or after the addition of the polymerizable monomer. You may combine.
In addition, a pH adjuster, a polymerization degree adjuster, an antifoaming agent, and the like can be appropriately added to the reaction system.

  The toner obtained by the production method and apparatus of the present invention preferably contains a wax in order to impart releasability. Any wax can be used as long as it has releasability.

Specifically, for example, olefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene and copolymer polyethylene; paraffin wax; ester waxes having a long-chain aliphatic group such as behenyl behenate, montanate ester, stearyl stearate A vegetable wax such as hydrogenated castor oil carnauba wax; a ketone having a long chain alkyl group such as distearyl ketone; a silicone having an alkyl group; a higher fatty acid such as stearic acid; a long chain aliphatic alcohol such as eicosanol; Examples include carboxylic acid esters or partial esters of polyhydric alcohols obtained from polyhydric alcohols such as erythritol and long chain fatty acids; higher fatty acid amides such as oleic acid amides and stearic acid amides; low molecular weight polyesters.

Among these waxes, in order to improve fixability, the melting point of the wax is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and particularly preferably 50 ° C. or higher. Moreover, 100 degrees C or less is preferable, 90 degrees C or less is more preferable, and 80 degrees C or less is especially preferable. If the melting point is too low, the wax may be exposed on the surface after fixing, and stickiness may occur. On the other hand, if the melting point is too high, the fixability at low temperatures may be poor.
The above waxes may be used alone or in combination. Further, the melting point of the wax compound can be appropriately selected depending on the fixing temperature for fixing the toner.

  In the present invention, the amount of the wax is preferably 1 part by mass or more per 100 parts by mass of the toner, more preferably 2 parts by mass or more, and further preferably 5 parts by mass or more. Moreover, it is preferable that it is 40 mass parts or less, More preferably, it is 35 mass parts or less, More preferably, it is 30 mass parts or less. When the wax content in the toner is less than the above range, the performance such as high temperature offset property may not be sufficient, and when it exceeds the above range, the blocking resistance is insufficient or the wax leaks from the toner. May contaminate the device.

  A known colorant can be arbitrarily used as the colorant of the present invention. Specific examples of the colorant include carbon black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow, rhodamine dyes, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dye, monoazo, Any known dyes and pigments such as disazo dyes and condensed azo dyes can be used alone or in combination. In the case of a full color toner, it is preferable to use benzidine yellow for yellow, monoazo and condensed azo dyes, magenta for quinacridone and monoazo dyes, and cyan for phthalocyanine blue. The colorant is preferably used so as to be 3 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymer primary particles.

  The blending of the colorant in the emulsion polymerization aggregation method is usually performed in an aggregation step. A dispersion of polymer primary particles and a dispersion of colorant particles are mixed to form a mixed dispersion, which is then aggregated to form a particle aggregate. The colorant is preferably used in a state of being dispersed in water in the presence of an emulsifier, and the volume average particle diameter of the colorant particles is 0.01 or more, more preferably 0.05 μm or more, and more preferably 3 μm or less. 1 μm.

  In the present invention, when a charge control agent is used, any known one can be used alone or in combination. For example, a quaternary ammonium salt, a basic or electron donating metal as a positive charge control agent. Substances such as metal chelates, metal salts of organic acids, metal-containing dyes, nigrosine dyes, amide group-containing compounds, phenolic compounds, naphthol compounds and their metal salts, urethane bond-containing compounds, Examples include acidic or electron-withdrawing organic substances.

In addition, when the toner for developing an electrostatic image obtained by the production method of the present invention is used as a toner other than a black toner in a color toner or a full color toner, a charge control agent that is colorless or light in color and does not impair the color tone of the toner is used. It is preferable to use, for example, a quaternary ammonium salt compound as a positively chargeable charge control agent, a metal salt of salicylic acid or an alkylsalicylic acid with chromium, zinc, aluminum, a metal complex as a negatively chargeable charge control agent, Hydroxys such as metal salts of benzylic acid, metal complexes, amide compounds, phenolic compounds, naphthol compounds, phenolamide compounds, 4,4′-methylenebis [2- [N- (4-chlorophenyl) amide] -3-hydroxynaphthalene] Naphthalene compounds are preferred.

  In the present invention, when a charge control agent is contained in the toner using the emulsion polymerization aggregation method, the charge control agent is added together with a polymerizable monomer or the like at the time of emulsion polymerization, or together with the polymer primary particles and the colorant. It can be blended by a method such as adding in the agglomeration step, or adding after the polymer primary particles and the colorant are aggregated to almost the target particle size. Among these, it is preferable to disperse the charge control agent in water using a surfactant and add it to the aggregation step as a dispersion having a volume average particle size of 0.01 μm or more and 3 μm or less.

In the emulsion polymerization aggregation method, the aggregation is usually carried out in a tank equipped with a stirrer, but there are a heating method, a method of adding an electrolyte, and a method of combining them. When polymer primary particles are agglomerated with stirring to obtain particle aggregates of the desired size, the particle size of the particle aggregates is controlled based on the balance between the agglomeration force between the particles and the shearing force due to agitation. However, the cohesive force can be increased by heating or adding an electrolyte.
In the present invention, the electrolyte in the case of performing aggregation by adding an electrolyte may be either an organic salt or an inorganic salt. Specifically, NaCl, KCl, LiCl, Na ₂ SO ₄ , K ₂ SO ₄ , Li ₂ SO ₄ , MgCl ₂ , CaCl ₂ , MgSO ₄ , CaSO ₄ , ZnSO ₄ , Al ₂ (SO ₄ ) ₃ , Fe ₂ (SO ₄ ) ₃ , CH ₃ COONa, C ₆ H ₅ SO ₃ Na, etc. It is done. Of these, inorganic salts having a divalent or higher polyvalent metal cation are preferred.

In the present invention, the amount of electrolyte added varies depending on the type of electrolyte, target particle size, etc., but is preferably 0.05 parts by mass or more, and 0.1 parts by mass with respect to 100 parts by mass of the solid component of the mixed dispersion. Part or more is more preferable. Further, it is preferably 25 parts by mass or less, more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. When the amount added is less than the above range, the agglomeration reaction progresses slowly and fine powders of 1 μm or less remain after the agglomeration reaction, and the average particle size of the obtained particle aggregate does not reach the target particle size. If the amount is larger than the above range, it is likely to be agglomerated rapidly, making it difficult to control the particle size, and the resulting agglomerated particles may contain problems such as coarse powder or irregular shapes. There is.
The aggregation temperature in the case of performing aggregation only by heating without using an electrolyte is preferably (Tg-20) ° C. or higher, and more preferably (Tg-10) ° C. or higher, where Tg is the glass transition temperature of the polymer primary particles. . Moreover, Tg or less is preferable and (Tg-5) degree C or less is preferable.

  The time required for agglomeration is optimized depending on the shape of the apparatus and the processing scale, but in order for the toner particle size to reach the target particle size, it is usually held at the predetermined temperature for at least 30 minutes. desirable. The temperature rise until reaching the predetermined temperature may be raised at a constant rate, or may be raised stepwise.

  If necessary, particles having adhered or fixed resin particles may be formed on the surface of the particle aggregate after the above-described aggregation treatment. In some cases, the chargeability and heat resistance of the obtained toner can be improved by attaching or fixing the resin particles whose properties are controlled to the surface of the particle aggregate, and the effect of the present invention can be further enhanced. .

When resin particles having a glass transition temperature higher than that of the polymer primary particles are used as the resin particles, it is preferable because blocking resistance can be further improved without impairing fixing properties. The volume average particle size of the resin particles is preferably 0.02 μm or more, and more preferably 0.05 μm or more. Moreover, 3 micrometers or less, Furthermore, 1.5 micrometers or less are preferable. As the resin particles, those obtained by emulsion polymerization of monomers similar to the polymerizable monomers used for the above-mentioned polymer primary particles can be used.
Resin particles are usually used as a dispersion dispersed in water or a liquid mainly composed of water with a surfactant. However, when a charge control agent is added after the aggregation treatment, charge control is performed on the dispersion containing particle aggregates. It is preferable to add the resin particles after adding the agent.

  In order to increase the stability of the particle aggregate obtained in the aggregation step, it is preferable to perform fusion in the aggregated particles in the aging step after the aggregation step. The temperature of the ripening step is preferably not less than Tg of the polymer primary particles, more preferably not less than 5 ° C higher than Tg, and preferably not more than 80 ° C higher than Tg, more preferably not less than 50 ° C higher than Tg. It is as follows. The time required for the aging step varies depending on the shape of the target toner, but after reaching the glass transition temperature or higher of the polymer primary particles, it is usually held for 0.1 to 10 hours, preferably 1 to 6 hours. Is desirable.

  In addition, it is preferable to add a surfactant or raise the pH value after the aggregation process, preferably before the aging process or during the aging process. As the surfactant used here, one or more emulsifiers can be selected from the emulsifiers that can be used when producing the polymer primary particles. In particular, the emulsifiers used when producing the polymer primary particles. It is preferable to use the same. Although the addition amount in the case of adding surfactant is not limited, Preferably it is 0.1 mass part or more with respect to 100 mass parts of solid components of a mixed dispersion, More preferably, it is 1 mass part or more, More preferably, it is 3 masses It is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less. After the aggregation process, before the completion of the ripening process, by adding a surfactant or raising the pH value, it is possible to suppress aggregation of the particle aggregates aggregated in the aggregation process, In some cases, the generation of coarse particles can be suppressed.

  By heat treatment in the aging step, the polymer primary particles in the aggregate are fused and integrated, and the toner particle shape as the aggregate becomes close to a spherical shape. The particle aggregate before the aging step is considered to be an aggregate due to electrostatic or physical aggregation of the polymer primary particles, but after the aging step, the polymer primary particles constituting the particle aggregate are fused to each other. In addition, the shape of the toner particles can be made nearly spherical. According to such an aging step, by controlling the temperature and time of the aging step, toners having various shapes such as a shape in which the polymer primary particles are aggregated, a spherical shape in which the fusion has progressed, and the like can be obtained. Can be manufactured.

  The obtained particles are subjected to solid-liquid separation by a known method, the particles are collected, and washed and dried as necessary to obtain target toner mother particles.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the following examples, “part” means “part by mass”.

<Measurement method of average particle diameter of polymer primary particles>
Nikkiso Co., Ltd., Model: Microtrac Nanotrac 150 (hereinafter abbreviated as “Nanotrack”), according to the instruction manual of NanoTrack, using its analysis software Microtrac Particle Analyzer Ver10.1.2.-019EE Using ion-exchanged water having a degree of 0.5 μS / cm as a dispersion medium, the measurement was performed by the method described in the instruction manual under the following conditions or by inputting the following conditions.

Solvent refractive index: 1.333
・ Measurement time: 100 seconds
・ Number of measurements: 1 time
-Particle refractive index: 1.59
・ Transparency: Transmission
・ Shape: Spherical shape
Density: 1.04

<Measurement method of weight average molecular weight Mw, peak molecular weight Mp>
It is measured by gel permeation chromatography (GPC) under the following conditions.
Apparatus: GPC apparatus HLC-8020 manufactured by Tosoh Corporation
Column: PL-gel Mixed-B 10 μ made by Polymer Laboratory
Reference column: TSKgel GMH manufactured by Tosoh Corporation
Solvent: THF
Sample concentration: 0.1% by weight
Calibration curve: Standard polystyrene

<Measurement method of volume median diameter (Dv50)>
Use Beckman Coulter's Multisizer III (aperture diameter 100 μm) (hereinafter abbreviated as “Multisizer”), use the company's Isoton II as the dispersion medium, and disperse so that the dispersoid concentration is 0.03% by mass. And measured. The measurement particle diameter range is from 2.00 to 64.00 μm, and this range is discretized into 256 divisions so as to be equidistant on a logarithmic scale, and the volume calculated based on the statistical values on the basis of the volume is the volume. The median diameter (Dv50) was used.

<Measurement method of circularity>
In the present invention, the “average circularity” is determined by dispersing toner base particles in a dispersion medium (Isoton II, manufactured by Beckman Coulter, Inc.) so as to be in the range of 5720 to 7140 particles / μL. The measurement is performed under the following apparatus conditions using a company (former Toa Medical Electronics Co., Ltd., FPIA 3000), and the value is defined as “average circularity”. In the present invention, the same measurement is performed three times, and an arithmetic average value of three “average circularity” is adopted as the “average circularity”.
・ Mode: HPF
-HPF analysis amount: 0.35 μL
-HPF detection number: 2000-2500

The following is measured by the above device and automatically calculated and displayed in the above device, and “circularity” is defined by the following formula.
[Circularity] = [Perimeter of a circle with the same area as the projected particle area] / [Perimeter of projected particle image]
And 2000-2500 which is the number of HPF detection is measured, and the arithmetic average (arithmetic mean) of the circularity of each individual particle is displayed on the apparatus as “average circularity”.

<Measuring method of average primary particle diameter of metal oxide particles>
In the present invention, the “average primary particle size” of the metal oxide particles was measured by image analysis of SEM photographs. Specifically, using a scanning electron microscope S4500 manufactured by Hitachi, Ltd., after taking an appropriate number of photographs of the particles magnified 30000 times, 100 particles were randomly selected and image analysis made by Mitani Corporation These equivalent circle diameters were measured by software WinROOF, and the average value was defined as “average primary particle diameter”.

<Measurement method of electrical resistance value>
The electrical resistance value is not particularly limited as long as the resistivity of the powder can be measured under an arbitrary pressure, but in the present invention, the powder resistance measurement system-PD51 type manufactured by Mitsubishi Chemical Corporation. Was used, and the sample filling amount was 2.0 g and the weight was 4 kN.

<Developer fluidity>
The fluidity of the developer in the present invention was measured by the following method.
Ferrite core carrier (BET specific surface area: 0.36m2 / g, fluidity: 42.8sec / 50g) covered with a silicone coating agent, made by Tokyo Tsutsui Rika Instruments Co., Ltd. Taito, micro type, so that the toner concentration is 6wt% A developer was prepared by mixing using a perspective mixer W-1-12971. Thereafter, fluidity (FR) was measured using JIS standard Z2504 manufactured by Tokyo Kuramoto Science Machinery Works. The measuring device had a diameter of 2.63, and the time for which 50 g of developer was discharged from the measuring device was measured to obtain the FR value (seconds / 50 g). The results are shown in Table 2.

<Carrier fluidity>
The carrier fluidity was measured using JIS standard Z2504 manufactured by Tokyo Kurochi Scientific Machinery. The measuring device had a diameter of 2.63, and the time for which the carrier 50 g was discharged from the measuring device was measured to obtain the carrier fluidity (second / 50 g).

[Preparation of replenishing toners a and b]
<Preparation of toner base particles A and B>
Toners a and b were obtained by externally adding the base particles A and B obtained at the blending ratio shown below.
・ 100 parts of polyester resin ・ 2 parts of charge control agent (BONTRON E-108 manufactured by Orient Chemical Industries Co., Ltd.) ・ 4 parts of polypropylene wax (550P manufactured by Sanyo Kasei Kogyo Co., Ltd.) ・ 8 parts of colorant (Daiichi Seika PB15: 3)

The above raw materials are mixed with a high-speed mixer, melt-kneaded with a twin-screw extruder, coarsely pulverized with a hammer mill, finely pulverized with a mechanical pulverizer, classified, and the volume median diameter is 7.0 μm. Particles P were obtained. To 100 parts by mass of toner base particles P, 0.5 parts by mass of hydrophobic silica having a particle diameter of 0.1 μm subjected to HMDS surface treatment as an external additive was added and mixed with a Henschel mixer. Then, using a surfing system (Nippon Pneumatic Industrial Co., Ltd.), heat treatment was performed at a hot air temperature of 300 ° C. and a dispersion concentration of 39 g / m ³ , and after heating using a cooling air of 20 ° C. Toner base particles A having a unit diameter of 7.3 μm and a circularity of 0.93 were obtained. Similarly, the hot air temperature is 36
By adjusting the temperature to 0 ° C., toner mother particles B having a volume median diameter of 7.3 μm and a circularity of 0.95 were obtained.

HMDS surface treatment as an external additive for 100 parts of the base particle A average primary particle size of 0.1 μm
2 parts of hydrophobic silica particles and hydrophobic silica particles 2 with an average primary particle size of 0.03 μm treated with HMDS
Toner a was prepared by adding 0.6 parts of titanium oxide particles having an average primary particle size of 0.02 μm that had been surface treated with isobutyltrimethoxysilane and mixing with a Henschel mixer. Similarly, toner b was prepared using base particles B.

[Preparation of toners 1 to 7 constituting initial developer]
<Preparation of toner mother particle C><Preparation of wax / long-chain polymerizable monomer dispersion>
27 parts of paraffin wax (HNP-9 manufactured by Nippon Seiki Co., Ltd.), 2.8 parts of stearyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.9 parts of 20% DBS aqueous solution and 68.3 parts of demineralized water were heated to 90 ° C. The mixture was stirred for 10 minutes using a homomixer (Mark II f model, manufactured by Koki Kogyo Co., Ltd.). Next, this dispersion was heated to 90 ° C., and circulation emulsification was started under a pressure condition of 25 MPa using a homogenizer (manufactured by Gorin, 15-M-8PA type). Dispersion was performed until the diameter (MV) reached 250 nm to prepare a wax / long-chain polymerizable monomer dispersion 1 (emulsion solid content concentration = 30.2%).

<Preparation of silicone wax dispersion>
27 parts of alkyl-modified silicone wax), 1.9 parts of 20% DBS aqueous solution, and 71.1 parts of demineralized water are placed in a stainless steel container and heated to 90 ° C. and homomixer (mark II manufactured by Tokushu Kika Kogyo Co., Ltd.).
f model) for 10 minutes. The dispersion was then heated to 99 ° C. and homogenizer (
Cyclic emulsification was started under pressure of 45 MPa using Gorin Co., Ltd., 15-M-8PA type, and dispersed until the volume average particle size (MV) reached 240 nm while measuring with Nanotrac and dispersed in silicone wax A liquid (emulsion solid content concentration = 27.4%) was prepared.

<Preparation of polymer primary particle dispersion 1>
35.6 parts by weight of wax / long-chain polymerizable monomer dispersion A1 and 259 demineralized water in a reactor equipped with a stirring device (three blades), a heating / cooling device, a concentrating device, and a raw material / auxiliary charging device The temperature was raised to 90 ° C. under a nitrogen stream while stirring and stirring.
Thereafter, the following mixture of monomers and an aqueous emulsifier solution was added over 5 hours from the start of polymerization while stirring was continued. The time when the mixture of the monomers and the emulsifier aqueous solution was started to be dropped was set as the polymerization start, and the following initiator aqueous solution was added over 4.5 hours from 30 minutes after the start of the polymerization. The aqueous solution of the agent was added over 2 hours, and the internal temperature was maintained at 90 ° C. for 1 hour while continuing stirring.

<Monomers>
Styrene 76.8 parts Butyl acrylate 23.2 parts Acrylic acid 1.5 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 0.7 part

<Emulsifier aqueous solution>
20% DBS aqueous solution 1.0 part demineralized water 67.1 parts <initiator aqueous solution>
8% aqueous hydrogen peroxide solution 15.5 parts 8% L (+)-ascorbic acid aqueous solution 15.5 parts
[Additional initiator aqueous solution]
8% L (+)-ascorbic acid aqueous solution 14.2 parts

  After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer primary particle dispersion 1. The volume average particle diameter (MV) measured using a nanotrack was 280 nm, and the solid content concentration was 21.1 wt%.

<Preparation of polymer primary particle dispersion 2>
In a reactor equipped with a stirring device (three blades), a heating / cooling device, a concentrating device, and a raw material / auxiliary charging device, 23.6 parts by weight of silicone wax dispersion A2, 1.5 parts by weight of 20% DBS aqueous solution, 324 parts of demineralized water was added, the temperature was raised to 90 ° C. under a nitrogen stream, and 3.2 parts of an 8% aqueous hydrogen peroxide solution and 3.2 parts of an 8% L (+)-ascorbic acid aqueous solution were added all at once with stirring. .
5 minutes later, polymerization of the following mixture of monomers and emulsifier aqueous solution was started (from the time when 3.2 parts of 8% hydrogen peroxide aqueous solution and 3.2 parts of 8% L (+)-ascorbic acid aqueous solution were added all at once. After 5 minutes), the following initiator aqueous solution was added over 6 hours from the start of polymerization, and the internal temperature was maintained at 90 ° C. for 1 hour with further stirring.

<Monomers>
Styrene 92.5 parts Butyl acrylate 7.5 parts Acrylic acid 1.5 parts Trichlorobromomethane 0.6 parts
[Emulsifier aqueous solution]
20% DBS aqueous solution 1.5 parts demineralized water 66.2 parts <initiator aqueous solution>
8% aqueous hydrogen peroxide solution 18.9 parts 8% L (+)-ascorbic acid aqueous solution 18.9 parts

  After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer primary particle dispersion 2. The volume average particle diameter (MV) measured using a nanotrack was 290 nm, and the solid content concentration was 19.0% by weight.

<Preparation of colorant dispersion>
In a container equipped with a stirrer (propeller blade), 5 parts of a colorant (Daiichi Seika PB15: 3), 1 part of a 20% DBS aqueous solution, 4 parts of a nonionic surfactant (Emulgen 120, manufactured by Kao Corporation), electrical conductivity Was added with 75 parts of ion exchange water of 2 μS / cm and predispersed to obtain a premix solution. This premix solution was supplied to a wet bead mill and subjected to one-pass dispersion. The stator inner diameter was 75 mm, the separator diameter was 60 mm, the distance between the separator and the disk was 15 mm, and zirconia beads having a diameter of 100 μm (true density of 6.0 g / cm 3) were used as a dispersion medium.
The blue colorant dispersion is obtained by continuously supplying the premix slurry from the supply port at a supply rate of 50 L / hr by a non-pulsating metering pump and continuously discharging from the discharge port while maintaining the rotation speed of the rotor constant. Obtained. The volume average diameter (MV) of the colorant in the colorant dispersion is 150 n.
m.

<Manufacture of mother particle D>
Polymer primary particle dispersion 1 95 parts as solids Polymer primary particle dispersion 2 5 parts as solids Colorant particle dispersion 6 parts as colorant solids 20% DBS aqueous solution 0.1 parts as solids

Using the above components, mother particles were produced by the following procedure.
Polymer primary particle dispersion 1 and 20% DBS aqueous solution were charged to a mixer equipped with a stirrer (double helical blade), heating / cooling device, concentrating device, and raw material / auxiliary charging device, and the internal temperature was 5 ° C. at 5 ° C. Mix evenly for minutes. Subsequently, while stirring at an internal temperature of 12 ° C., 0.52 part of a 5% aqueous solution of ferrous sulfate as FeSO ₄ .7H ₂ O was added over 5 minutes, and then the colorant particle dispersion was added over 5 minutes. The mixture was uniformly mixed at an internal temperature of 12 ° C., and a 0.5% aqueous solution of aluminum sulfate was added dropwise under the same conditions (the solid content with respect to the resin solid content was 0.10 parts). Thereafter, the temperature was raised to 53 ° C. over 75 minutes, and further raised to 56 ° C. over 90 minutes. Here, when the volume median diameter was measured using a multisizer, it was 5.2 μm. Thereafter, the polymer primary particle dispersion 2 was added over 3 minutes and held for 60 minutes, followed by addition of a 20% DBS aqueous solution (6 parts as solids) over 10 minutes, followed by 90 minutes over 30 minutes. The temperature was raised to 0 ° C. and held for 75 minutes.
Thereafter, the slurry obtained by cooling to 30 ° C. over 20 minutes was extracted, and suction filtration was performed with an aspirator using 5 types C (No5C manufactured by Toyo Roshi Kaisha, Ltd.) filter paper. The cake remaining on the filter paper is transferred to a stainless steel container equipped with a stirrer (propeller blade), ion-exchanged water having an electric conductivity of 1 μS / cm is added, and the mixture is stirred to uniformly disperse, and then stirred for 30 minutes. did.
Then, suction filtration is performed with an aspirator again using filter paper of 5 types C (Toyo Filter Paper Co., Ltd. No5C), and the solid matter remaining on the filter paper is again equipped with a stirrer (propeller blade) and has an electric conductivity of 1 μS / cm. It was transferred to a container containing ion-exchanged water and stirred to uniformly disperse it and kept stirring for 30 minutes. When this process was repeated 5 times, the electrical conductivity of the filtrate was 2 μS / cm.

  The cake obtained here was dried for 48 hours in an air dryer set at 40 ° C. to obtain mother particles D. The mother particle D had a volume median diameter of 6.5 μm and a circularity of 0.96.

[Preparation of Toner 1 Using Toner Base Particle C]
To 100 parts of the base particle D, 1 part of external additive 1 as an additive, 1.2 parts of external additive 2 and 0.3 part of external additive 3 are added and mixed with a Henschel mixer to prepare toner 1. did. The external additives used were those shown in Table 1. The fluidity of the produced toner 1 was measured and shown in Table 2.

[Production of Toners 2 to 7 Using Toner Base Particles C]
Toner 2 to toner 7 were prepared in the same manner as the toner 1 preparation method except that the external additive formulation shown in Table 2 was used for 100 parts of toner base particles C. The external additives used were those shown in Table 1. The fluidity of the produced toners 2 to 7 was measured and shown in Table 2.

<Example 1>
The toner bottle of the developing cartridge is filled with toner 1, and a 5,000-sheet image is printed with a two-component developing type commercial printer (printing speed 45 sheets / min, non-magnetic two-component, organic photoreceptor, transfer is a full-color printer with an intermediate transfer belt). Output was done. The carrier used for the developer at this time was a ferrite core carrier coated with a silicone coating agent, and had a BET specific surface area of 0.81 m ² / g and a fluidity of 28.07 seconds / 50 g. This developer is referred to as an initial developer. Thereafter, the toner bottle filled with the toner 1 and the toner bottle filled with the toner a were exchanged, and 1000 sheets of images were output. Table 3 shows the results of the presence or absence of the occurrence of paper stains, the consumption of toner a, and the presence or absence of in-machine scattering.

<Example 2 to Example 3, Comparative Example 1 to Comparative Example 3>
In Example 1, the same operation as in Example 1 was performed except that toner 1 as the toner constituting the initial developer was replaced with toners 2 to 6, and Examples 2 to 3 and Comparative Example 1 shown in Table 3 were performed. -The result of Comparative Example 3 was obtained.

<Image quality evaluation method>
(1) Paper smudges The paper surface output from the image forming apparatus was visually checked to see if it was smudged. A mark “O” was obtained when the smudge was apparent, a mark “△” was obtained when it was slightly confirmed, and a mark “x” was found.
(2) Consumption amount ratio In Example 3, the toner consumption amount required to output 1000 sheets using toner a is used as a reference, and in Examples 1, 2 and Comparative Examples 1 to 3, the toner 100 using a
The ratio to the toner consumption required to output 0 sheets was determined.
(3) In-machine scattering The amount of scattered toner inside the image forming apparatus was observed and judged based on Example 3.
○: No dirt or equivalent to or more than Example 3 △: Dirty than Example 3, but usable x: Unusable due to dirt (4) Comprehensive judgment ◎ If paper stains and in-machine splashes are ◯, paper Dirt ◯ if it is △ in-machine scattering △, △ if paper dirt △ in-machine scattering ×, 、 if paper dirt and in-machine scattering x.

<Example 4>
The same operation as in Example 1 was performed except that toner a was replaced with toner b in Example 1, and the results shown in Table 4 were obtained.

<Example 5 to Example 6, Comparative Example 4 to Comparative Example 7>
In Example 4, the same operation as in Example 4 was performed except that toner 1 constituting the initial developer was replaced with toners 2 to 7, and Examples 5 to 6 and Comparative Examples 4 to 4 shown in Table 4 were performed. A result of 7 was obtained.

  As described above, by controlling the fluidity of a developer containing toner having a specific external additive within a certain range, the toner carried on the carrier can be smoothly replaced even when various toners are replenished. A stable image can be obtained. This provides tremendous industrial benefits.

Claims (10)

A step of forming an electrostatic latent image on the image carrier, a step of developing the electrostatic latent image with a two-component developer containing a toner for developing an electrostatic charge image and a carrier, and forming a toner image, and a replenishment toner sequentially An image forming method including a replenishing step,
When the toner concentration in the two-component developer is 6 wt%, the fluidity of the two-component developer is 100 seconds / 50 g or more, and as an external additive for the toner filled in the developing cartridge and / or the replenishment toner. A positively charged metal oxide particle having a BET specific surface area of 100 m ² / g or more and ^two negatively charged metal oxide particles having a BET specific surface area of 110 m ² / g or less and different BET specific surface areas. An image forming method. 2. The positively charged metal oxide particles are contained in an amount of 0.2 parts by mass or more and 0.5 parts by mass or less based on 100 parts by mass of toner and / or replenishment toner filled in the developing cartridge. Image forming method. 3. The image forming method according to claim 1, wherein the two types of negatively charged metal oxide particles each have a BET specific surface area of 25 m ² / g or more. The image forming method according to any one of claims 1 to 3, wherein the negatively charged metal oxide particles and / or the positively charged metal particles are imparted with hydrophobicity by surface treatment. 5. The image forming method according to claim 1, wherein the positively charged metal oxide particles are silica particles, and the two kinds of negatively charged metal oxide particles are titanium oxide particles and silica particles. The image forming method according to claim 1, wherein the negatively charged metal oxide particles include three types of particles having a BET specific surface area of 110 m ² / g or less and different BET specific surface areas.   7. The image forming method according to claim 1, wherein the volume median diameter of the toner filled in the developing cartridge and the replenishing toner is 4 μm or more and 8 μm or less.   8. The image forming method according to claim 1, wherein the toner filled in the developing cartridge and the replenishment toner have an average circularity of 0.91 or more and 0.99 or less. The image forming method according to claim 1, wherein the carrier has a BET specific surface area of 0.1 m ² / g or more and 1 m ² / g or less.   The image forming method according to claim 1, wherein the fluidity of the carrier is 20 seconds / 50 g or more and 50 seconds / 50 g or less.