JP2015031715A5 - - Google Patents

Description

[Measurement method of fine particle release rate from toner]
In belt donor plurality of external additive is externally added, when measuring the liberation percentage of fine particles of the present invention to remove the fine particles and the external additive from the preparative toner particles, further isolating a plurality of types of external additives・ It needs to be collected.

Specific examples of the method include the following methods.
(1) placed bets toner 5g sample bottle, methanol is added 200 ml.
(2) The sample is dispersed for 5 minutes with an ultrasonic cleaner to separate the external additive.
(3) suction filtration (10 [mu] m membrane filter) and separates the door toner particles and external additive. In the case of magnetic toner , a neodymium magnet may be applied to the bottom of the sample bottle to fix the magnetic toner particles and only the supernatant liquid may be separated.
(4) Perform the above (2) and (3) three times.

By the operation, externally added particulates and the external additive is isolated from preparative toner particles. The collected aqueous solution is centrifuged to separate and collect the silica fine particles and the fine particles of the present invention. Next, the solvent is removed, the film is sufficiently dried with a vacuum drier, and the weight is measured to obtain the free amount of fine particles.

<Example 1>
In this embodiment, the organic / inorganic composite fine particles 1 are placed in the fine particle supply means 400, and the supply amount is adjusted so that the coverage of the fine particles on the surface of the charging roller 120 is about 30%. The developing device 140 is filled with magnetic toner particles 6 to evaluate charging unevenness. Table 3 shows the evaluation results of the coverage of the organic-inorganic composite fine particles 1 on the surface of the charging roller 120, the evaluation of the release rate of fine particles from the toner, and the image evaluation results.

<Example 6>
In this embodiment, the organic / inorganic composite fine particles 4 are placed in the fine particle supply means 400, and the supply amount is adjusted so that the coverage of the fine particles on the surface of the charging roller 120 is about 30%. Other than that, the charging unevenness is evaluated as the same configuration and conditions as in the first embodiment. The evaluation results are shown in Table 3.

<Example 9>
In this embodiment, instead of the magnetic toner particles 1, the developing device 140 is filled with the magnetic toner particles 2. Otherwise, the charging unevenness is evaluated as the same configuration and conditions as in Example 8 . The evaluation results are shown in Table 3.

<Example 10>
In this embodiment, instead of the magnetic toner particles 1, the developing device 140 is filled with the magnetic toner particles 3. Otherwise, the charging unevenness is evaluated as the same configuration and conditions as in Example 8 . The evaluation results are shown in Table 3.

Claims (5)

A charging step of charging the image carrier negatively using a contact charging means that contacts the image carrier;
An electrostatic latent image forming step of forming an electrostatic latent image on the image carrier;
Developing the electrostatic latent image with a negatively charged toner to form a toner image;
A transfer step of transferring the toner image to a recording medium;
An image forming method comprising:
A charging bias in which an AC bias and a DC bias are superimposed is applied to the contact charging unit,
In the charging step, charging is performed in a state in which negatively chargeable fine particles are interposed between the contact charging unit and the image carrier so that the surface of the contact charging unit covers 10% or more and 70% or less. Is performed,
The fine particle has a volume resistivity of 1.0 × 10 ¹¹ Ω · cm or more and a relative dielectric constant at 1 kHz of 1.7 or more and 2.5 or less. A charging step of charging the image carrier negatively by applying a charging bias in which an AC bias and a DC bias are superposed using a contact charging means that contacts the image carrier;
An electrostatic latent image forming step of forming an electrostatic latent image on the image carrier;
A developing step of developing the electrostatic latent image with a negatively charged toner to form a toner image;
A transfer step of transferring the toner image to a recording medium;
A toner used in an image forming method having
The toner has toner base particles containing a binder resin and a colorant, and negatively charged fine particles are externally added to the surface.
The fine particles have a volume resistivity of 1.0 × 10 ¹¹ Ω · cm or more, a relative dielectric constant at 1 kHz of 1.7 or more and 2.5 or less, and a release rate of the fine particles from the toner of 10% or more. A toner characterized by being.   The zeta potential of the toner base particles when the toner base particles are dispersed in water is ζ (T), and the zeta potential of the microparticles when the fine particles are dispersed in water is ζ (A). The toner according to claim 2, wherein an absolute value | ζ (T) −ζ (A) | of a difference between ζ (T) and the ζ (A) is 50 mV or less. A charging step of charging the image carrier negatively by applying a charging bias in which an AC bias and a DC bias are superposed using a contact charging means that contacts the image carrier;
An electrostatic latent image forming step of forming an electrostatic latent image on the image carrier;
A developing step of developing the electrostatic latent image with a negatively charged toner to form a toner image;
A transfer step of transferring the toner image to a recording medium;
An image forming method comprising:
The toner has toner base particles containing a binder resin and a colorant, and negatively charged fine particles are externally added to the surface.
The fine particles have a volume resistivity of 1.0 × 10. ¹¹ An image forming method, wherein the dielectric constant at 1 kHz is 1.7 or more and 2.5 or less, and the release rate of the fine particles from the toner is 10% or more. The zeta potential of the toner base particles when the toner base particles are dispersed in water is ζ (T), and the zeta potential of the microparticles when the fine particles are dispersed in water is ζ (A). 5. The image forming method according to claim 4, wherein an absolute value | ζ (T) −ζ (A) | of a difference between ζ (T) and the ζ (A) is 50 mV or less .