JP7443810B2 - Image forming method and image forming system - Google Patents

Description

The present invention relates to an image forming method and an image forming system. More specifically, the present invention relates to an image forming method and an image forming system that can suppress excessive charging of an electrostatic image developing toner in a low temperature, low humidity environment and improve fine line reproducibility.

In recent years, electrophotography has become widespread in the commercial printing field, and there is a need for a system that can provide high-quality printed matter more quickly.
In such an electrophotographic system, an electrophotographic photoreceptor (hereinafter also simply referred to as "photoreceptor") having a fast response speed is used.

For example, Patent Document 1 discloses an invention that improves the charge transport speed of a photoreceptor by using a triphenylamine compound with a specific structure as a charge transport substance.

However, molecules with relatively large conjugated systems, such as triphenylamine compounds, have a fast charge transfer speed, but the charge is easily diffused during transfer, so the potential of the image area during latent image formation on the photoreceptor is In some cases, the reduction was not sufficient.

Particularly in a low-temperature, low-humidity environment, the toner for developing electrostatic images (hereinafter also simply referred to as "toner") tends to deteriorate in developability due to excessive charging, so that the deterioration in fine line reproducibility may become noticeable.

JP2019-61150A

The present invention has been made in view of the above-mentioned problems and circumstances, and an object of the present invention is to form an image that can suppress excessive charging of toner for developing electrostatic images in a low-temperature, low-humidity environment and improve fine line reproducibility. A method and an imaging system are provided.

In order to solve the above problems, the present inventor used an electrostatic image developing toner and an electrophotographic photoreceptor in the process of investigating the causes of the above problems, and at least the charging process, the exposure process, the developing process, and the transfer process. An image forming method, wherein the electrophotographic photoreceptor has a photosensitive layer, the photosensitive layer contains a compound having a structure represented by the following general formula (1) as a charge transport substance, and discovered that the above-mentioned problems could be solved by containing titanic acid compound particles having a primary particle number average particle diameter of 10 to 80 nm as an external additive in the toner for developing electrostatic images, and the present invention It's arrived.

That is, the above-mentioned problems related to the present invention are solved by the following means.

（一般式（１）中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５及びＲ^６は、各々独立に、水素原子、ハロゲン原子、炭素数１～２０のアルキル基、炭素数１～２０のアルコキシ基、又は、炭素数６～３０のアリール基を表し、隣接する２つの置換基同士が結合して炭化水素環構造を形成してもよい。ｐ及びｑは、各々独立に、０、１又は２を表す。一般式（２）中、Ｒ ^Ｃ２１ 、Ｒ ^Ｃ２２ 、及びＲ ^Ｃ２３ は、各々独立に、水素原子、ハロゲン原子、炭素数１～１０のアルキル基、炭素数１～１０のアルコキシ基又は炭素数６～１０のアリール基を表す。） 1. An image forming method using an electrostatic image developing toner and an electrophotographic photoreceptor and comprising at least a charging step, an exposure step, a developing step, and a transfer step,
The electrophotographic photoreceptor has a photosensitive layer,
The photosensitive layer contains a compound having a structure represented by the following general formula (1) and a compound having a structure represented by the following general formula (2) as a charge transport substance ,
The electrostatic image developing toner contains titanic acid compound particles whose primary particles have a number average diameter of 10 to 80 nm and silica particles whose primary particles have a number average diameter of 5 to 40 nm as external additives. Contains
The coefficient of variation of the particle size distribution of the silica particles is 20% or less,
The titanate compound particles further contain one or more elements selected from lanthanum, tin, silicon, magnesium, strontium, calcium, or barium, and
An image forming method characterized by using strontium titanate particles, calcium titanate particles, or barium titanate particles .

(In general formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and a carbon number 1 to 20 alkoxy group or an aryl group having 6 to 30 carbon atoms, and two adjacent substituents may be bonded to each other to form a hydrocarbon ring structure. p and q each independently represent 0 , 1 or 2. In the general formula (2), R ^C21 , R ^C22 , and R ^C23 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or a C 1 to 10 alkyl group. Represents an alkoxy group or an aryl group having 6 to 10 carbon atoms. )

2 . the titanic acid compound particles contain lanthanum , and
2. The image forming method according to item 1 , wherein the particles are strontium titanate particles, calcium titanate particles, or barium titanate particles .

8. An image forming system using an electrostatic image developing toner and an electrophotographic photoreceptor and having at least a charging step, an exposure step, a developing step, and a transfer step, wherein the image forming method according to item 1 or 2 is carried out. An image forming system characterized by:

By the means of the present invention, an image forming method and an image forming system are capable of enabling high-speed printing, suppressing excessive charging of electrostatic image developing toner in a low-temperature, low-humidity environment, and improving fine line reproducibility. can be provided.

Although the mechanism of expression or action of the effects of the present invention is not clear, it is speculated as follows.

Triphenylamine compounds with a specific structure have a large conjugated system and therefore have a high charge transport speed.
By adding such a compound to the photosensitive layer as a charge transport substance, an electrophotographic photoreceptor with excellent high-speed response can be obtained.

However, since the conjugated system is large, the charge tends to diffuse, and the potential drop in the image area tends to be insufficient in forming a latent image. Particularly in a low-temperature, low-humidity environment, the developability of an electrostatic image developing toner (hereinafter also simply referred to as "toner") tends to deteriorate, which may deteriorate the reproducibility of fine lines.

Here, since the titanate compound has low electrical resistance, the charges accumulated in the toner are easily released through the titanate compound particles.
Therefore, by incorporating titanate compound particles whose primary particle number average particle size is within an appropriate range as an external additive into the toner, excessive charging of the toner can be suppressed even in low temperature and low humidity environments, and fine line reproducibility can be improved. can be improved.

By making the number average particle size of the primary particles relatively small within the range of 10 to 80 nm, the titanic acid compound can be easily dispersed uniformly on the toner surface and is less likely to be buried or detached.
Therefore, excessive charging of the toner can be easily suppressed over a long period of time.

A schematic partial cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the present embodiment A schematic diagram showing an example of the overall configuration of an electrophotographic image forming apparatus used in the image forming method and image forming system of the present invention.

The image forming method of the present invention uses an electrostatic image developing toner and an electrophotographic photoreceptor, and includes at least a charging step, an exposure step, a development step, and a transfer step, wherein the electrophotographic photoreceptor is has a photosensitive layer, the photosensitive layer contains a compound having the structure represented by the general formula (1) as a charge transport substance, and the toner for developing an electrostatic image contains a primary additive as an external additive. It is characterized by containing titanic acid compound particles having a number average particle diameter within the range of 10 to 80 nm.
This feature is a technical feature common to or corresponding to each of the embodiments described below.

In an embodiment of the present invention, the titanate compound particles further contain a metal element other than titanium, thereby reducing electrical resistance .

Specifically, the titanate compound particles further contain one or more elements selected from lanthanum, tin, silicon, magnesium, strontium, calcium, or barium .

Furthermore, the titanate compound particles are strontium titanate particles, calcium titanate particles, or barium titanate particles, and the particle size can be easily controlled in manufacturing.
Moreover, it is preferable that the titanic acid compound particles contain lanthanum .

In an embodiment of the present invention, the photosensitive layer further contains a compound having a structure represented by the general formula (2), and has excellent mechanical strength.

Further, the toner for developing an electrostatic image contains silica particles having a number average diameter of primary particles in the range of 5 to 40 nm as an external additive, and the coefficient of variation of the particle size distribution of the silica particles is 20 nm. % or less , which improves the dispersibility on the toner surface.

The image forming method of the present invention uses a developing toner and an electrophotographic photoreceptor and is suitably used in an image forming system having at least a charging step, an exposure step, a developing step, and a transfer step.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention, its constituent elements, and forms and aspects for carrying out the present invention will be described below. In this application, "~" is used to include the numerical values described before and after it as a lower limit value and an upper limit value.

[Overview of the image forming method and image forming system of the present invention]
The image forming method and image forming system of the present invention use an electrostatic image developing toner and an electrophotographic photoreceptor, and include at least a charging step, an exposure step, a developing step, and a transfer step, The photographic photoreceptor has a photosensitive layer, and the photosensitive layer contains a compound having a structure represented by the general formula (1) and a compound having a structure represented by the general formula (2) as a charge transport substance. The electrostatic image developing toner contains , as external additives, titanic acid compound particles whose primary particles have a number average particle diameter of 10 to 80 nm and whose primary particles have a number average diameter of 5 to 40 nm. contains silica particles , the coefficient of variation of the particle size distribution of the silica particles is 20% or less, and the titanate compound particles contain one or more elements selected from lanthanum, tin, silicon, magnesium, strontium, calcium, or barium. It is characterized in that it further contains strontium titanate particles, calcium titanate particles, or barium titanate particles .

Note that the image forming system of the present invention forms an image using the toner for developing an electrostatic image according to the present invention in an image forming apparatus equipped with the electrophotographic photoreceptor according to the present invention and capable of performing the steps such as the above-mentioned steps. It is a system.
Components of the image forming method and image forming system of the present invention will be sequentially explained below.

1. Steps in Image Forming Method The image forming method of the present invention uses an electrostatic image developing toner and an electrophotographic photoreceptor, and includes at least a charging step, an exposure step, a developing step, and a transfer step.
The process preferably includes the following various steps. Details of each step will be described later.

(a) A step of charging an electrophotographic photoreceptor (also referred to as a "photoreceptor" or an "image carrier") (b) A step of forming an electrostatic latent image by exposing the charged photoreceptor to light (c ) Developing the electrostatic latent image with an electrostatic image developing toner (d) Transferring the developed toner image to a transfer material (e) Fixing the toner image transferred to the transfer material (f) A step of cleaning the top of the photoreceptor with a cleaning blade after transferring the toner image.

2. Electrophotographic Photoreceptor The electrophotographic photoreceptor according to the present invention is characterized in that it has a photosensitive layer, and the photosensitive layer contains a compound having a structure represented by the general formula (1) as a charge transport substance. shall be.
FIG. 1 shows a schematic partial cross-sectional view of an example of the layer structure of an electrophotographic photoreceptor. The electrophotographic photoreceptor 7 shown in FIG. 1 has a structure in which a subbing layer 1, a charge generation layer 2, and a charge transport layer 3 are laminated in this order on a conductive support 4. The charge generation layer 2 and the charge transport layer 3 constitute a photosensitive layer 5.

Note that the electrophotographic photoreceptor 7 may have a layered structure in which the subbing layer 1 is not provided. Further, the electrophotographic photoreceptor 7 may be a single-layer photosensitive layer in which the functions of the charge generation layer 2 and the charge transport layer 3 are integrated.
Each element of the electrophotographic photoreceptor will be explained below. Note that the reference numerals of each element will be omitted in the description.

2.1. Photosensitive Layer The photosensitive layer according to the present invention includes a charge generation layer and a charge transport layer, which perform charge generation or charge transport functions.
The photosensitive layer is characterized in that it contains a compound having a structure represented by the following general formula (1), which is a triphenylamine compound with a specific structure, as a charge transporting substance.

The photosensitive layer further contains a compound having a structure represented by the following general formula (2), which is a benzidine-based compound with a specific structure, as a charge transport substance, and has excellent mechanical strength.

The photosensitive layer may be a single layer or may be divided into layers for each function.
When the photosensitive layer is a single layer (charge generation/charge transport layer), for example, it is a layer containing a charge generation substance, a charge transport substance, and, if necessary, a binder resin and other known additives. . Note that these materials are the same as those described in the charge generation layer and charge transport layer described later.

When the photosensitive layer is a single layer, the content of the charge generating substance is preferably in the range of 0.1 to 10% by weight, preferably in the range of 0.8 to 5% by weight based on the total solid content. It is. Further, the content of the charge transport substance in the single-layer type photosensitive layer is preferably within the range of 5 to 50% by mass based on the total solid content.

The method for forming the single layer is the same as the method for forming a charge generation layer and a charge transport layer, which will be described later.
The thickness of the single layer is, for example, preferably in the range of 5 to 50 μm, preferably in the range of 10 to 40 μm.

2.1.1. Charge Transport Layer The charge transport layer is, for example, a layer containing a charge transport substance and a binder resin.

(charge transport material)
The photosensitive layer according to the present invention is characterized in that it contains a compound having a structure represented by the general formula (1), which is a triphenylamine compound having a specific structure, as a charge transporting substance.

The photosensitive layer further contains a compound having a structure represented by the general formula (2), which is a benzidine-based compound with a specific structure, as a charge transport substance, and has excellent mechanical strength.

Furthermore, R ^C21 to R ^C23 in the general formula (2) are preferably hydrogen atoms or alkyl groups having 1 to 3 carbon atoms from the viewpoint of solubility in the resin.

[Triphenylamine charge transport substance]
The triphenylamine charge transport material is a charge transport material in which three groups containing a butadiene structure "-CH=CH-CH=C=" are connected to a triphenylamine structure. Specifically, it is a charge transport substance in which a group containing a butadiene structure "-CH=CH-CH=C=" is linked to three phenol skeletons of a triphenylamine structure.

More specifically, for example, the triphenylamine compound includes a charge transport substance represented by the following general formula (1).

(In general formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and a carbon number 1 It represents an alkoxy group having ~20 carbon atoms or an aryl group having 6 to 30 carbon atoms, and two adjacent substituents may be bonded to each other to form a hydrocarbon ring structure. p and q each independently represent (represents 0, 1 or 2)

In general formula (1), examples of the halogen atoms represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. Among these, the halogen atom is preferably a fluorine atom or a chlorine atom, and more preferably a chlorine atom.

In general formula (1), the alkyl group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ has a carbon number of 1 to 20 (preferably 1 or more and 6 or less, more preferably 1 or more). 4 or less) linear or branched alkyl groups.

Specifically, the linear alkyl group includes methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n- Nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n- Examples include nonadecyl group and n-icosyl group.

Specifically, the branched alkyl group includes an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, and a tert-hexyl group. , isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert- Decyl group, isoundecyl group, sec-undecyl group, tert-undecyl group, neoundecyl group, isododecyl group, sec-dodecyl group, tert-dodecyl group, neododecyl group, isotridecyl group, sec-tridecyl group, tert-tridecyl group, neotridecyl group , isotetradecyl group, sec-tetradecyl group, tert-tetradecyl group, neotetradecyl group, 1-isobutyl-4-ethyloctyl group, isopentadecyl group, sec-pentadecyl group, tert-pentadecyl group, neopentadecyl group , isohexadecyl group, sec-hexadecyl group, tert-hexadecyl group, neohexadecyl group, 1-methylpentadecyl group, isoheptadecyl group, sec-heptadecyl group, tert-heptadecyl group, neoheptadecyl group, isooctadecyl group, sec- Octadecyl group, tert-octadecyl group, neooctadecyl group, isononadecyl group, sec-nonadecyl group, tert-nonadecyl group, neononadecyl group, 1-methyloctyl group, isoicosyl group, sec-icosyl group, tert-icosyl group, neoicosyl group, etc. can be mentioned.

Among these, as the alkyl group, lower alkyl groups such as methyl group, ethyl group, and isopropyl group are preferable.

In general formula (1), the alkoxy group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ has 1 to 20 carbon atoms (preferably 1 to 6, more preferably 1 to 4 carbon atoms). ) linear or branched alkoxy groups.

Specifically, the linear alkoxy group includes methoxy group, ethoxy group, n-propoxy group, n-butoxy group, n-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group. group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group, n-dodecyloxy group, n-tridecyloxy group, n-tetradecyloxy group, n-pentadecyloxy group, n-hexadecyl Examples include oxy group, n-heptadecyloxy group, n-octadecyloxy group, n-nonadecyloxy group, and n-icosyloxy group.

Specifically, branched alkoxy groups include isopropoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, isopentyloxy group, neopentyloxy group, tert-pentyloxy group, isohexyloxy group, sec -hexyloxy group, tert-hexyloxy group, isoheptyloxy group, sec-heptyloxy group, tert-heptyloxy group, isooctyloxy group, sec-octyloxy group, tert-octyloxy group, isononyloxy group, sec-nonyloxy group, tert-nonyloxy group, isodecyloxy group, sec-decyloxy group, tert-decyloxy group, isoundecyloxy group, sec-undecyloxy group, tert-undecyloxy group, neoundecyloxy group , isododecyloxy group, sec-dodecyloxy group, tert-dodecyloxy group, neododecyloxy group, isotridecyloxy group, sec-tridecyloxy group, tert-tridecyloxy group, neotridecyloxy group, iso Tetradecyloxy group, sec-tetradecyloxy group, tert-tetradecyloxy group, neotetradecyloxy group, 1-isobutyl-4-ethyloctyloxy group, isopentadecyloxy group, sec-pentadecyloxy group, tert - Pentadecyloxy group, neopentadecyloxy group, isohexadecyloxy group, sec-hexadecyloxy group, tert-hexadecyloxy group, neohexadecyloxy group, 1-methylpentadecyloxy group, isoheptadecyloxy group group, sec-heptadecyloxy group, tert-heptadecyloxy group, neoheptadecyloxy group, isooctadecyloxy group, sec-octadecyloxy group, tert-octadecyloxy group, neooctadecyloxy group, isononadecyloxy group, Examples include sec-nonadecyloxy group, tert-nonadecyloxy group, neononadecyloxy group, 1-methyloctyloxy group, isoicosyloxy group, sec-icosyloxy group, tert-icosyloxy group, neoicosyloxy group, and the like.

Among these, a methoxy group is preferred as the alkoxy group.

In general formula (1), the phenyl group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ has a carbon number of 6 to 30 (preferably 6 to 20, more preferably 6 to 16 carbon atoms). ) phenyl group.

In general formula (1), each of the above-mentioned substituents represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ also includes a group having a further substituent. Examples of the substituent include the atoms and groups exemplified above (eg, halogen atom, alkyl group, alkoxy group, aryl group, etc.).

In general formula (1), two adjacent substituents of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ (for example, R ¹ and R ² together, R ³ and R ⁴ together, R In the hydrocarbon ring structure in which ^{R 5} and R ⁶ are connected, examples of the group connecting the substituents include a single bond, a 2,2'-methylene group, a 2,2'-ethylene group, a 2,2'- Examples include a vinylene group, and among these, a single bond and a 2,2'-methylene group are preferred.

Here, specific examples of the hydrocarbon ring structure include a cycloalkane structure, a cycloalkene structure, and a cycloalkane polyene structure.

In general formula (1), p and q are preferably 1.

In general formula (1), from the viewpoint of forming a photosensitive layer (charge transport layer) with high charge transport ability, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are hydrogen atoms and have 1 to 1 carbon atoms. 20 alkyl group or an alkoxy group having 1 to 20 carbon atoms, p and q preferably represent 1 or 2, and R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are More preferably, it represents a hydrogen atom, and p and q represent 1.

That is, the triphenylamine-based charge transport substance is more preferably a charge transport substance represented by the following structural formula (1A) (exemplified compound (CT1-3)).

Specific examples of the triphenylamine charge transport material (CT1) are shown below, but the present invention is not limited thereto.

The abbreviations in the above exemplary compounds have the following meanings. Moreover, the number attached before a substituent shows the substitution position with respect to a benzene ring.
・-CH ₃ : Methyl group ・-OCH ₃ : Methoxy group

Here, the proportion of the triphenylamine charge transport substance in the charge transport substance is preferably within the range of 10 to 60% by mass, more preferably within the range of 30 to 50% by mass.

[Benzidine-based charge transport substance]
The benzidine-based charge transport material is a charge transport material having a benzidine structure "N-Ph-Ph-N (where Ph=phenyl group)".
Specifically, the benzidine-based charge transport substance includes a charge transport substance represented by the following general formula (2).

(In general formula (2), R ^C21 , R ^C22 , and R ^C23 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a 6 carbon atom ~10 aryl groups)

In the general formula (2), the halogen atoms represented by R ^C21 , R ^C22 , and R ^C23 include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like. Among these, the halogen atom is preferably a fluorine atom or a chlorine atom, and more preferably a chlorine atom.

In general formula (2), the alkyl group represented by R ^C21 , R ^C22 , and R ^C23 is a linear or branched alkyl group having 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 4). Examples include alkyl groups.

Specifically, the linear alkyl group includes methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n- Examples include nonyl group and n-decyl group.

Specifically, the branched alkyl group includes an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, and a tert-hexyl group. , isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert- Examples include decyl group.

Among these, as the alkyl group, lower alkyl groups such as methyl group, ethyl group, and isopropyl group are preferable.

In the general formula (2), the alkoxy group represented by R ^C21 , R ^C22 , and R ^C23 is a linear or branched group having 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 4). Examples include alkoxy groups.

Specifically, the linear alkoxy group includes methoxy group, ethoxy group, n-propoxy group, n-butoxy group, n-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group. group, n-nonyloxy group, n-decyloxy group, etc.

Specifically, the branched alkoxy group includes isopropoxy group, isobutoxy group, sec
-butoxy group, tert-butoxy group, isopentyloxy group, neopentyloxy group, tert-pentyloxy group, isohexyloxy group, sec-hexyloxy group, tert-hexyloxy group, isoheptyloxy group, sec-heptyl Oxy group, tert-heptyloxy group, isooctyloxy group, sec-octyloxy group, tert-octyloxy group, isononyloxy group, sec-nonyloxy group, tert-nonyloxy group, isodecyloxy group, sec-decyloxy group , tert-decyloxy group and the like.
Among these, a methoxy group is preferred as the alkoxy group.

In general formula (2), the aryl group represented by R ^C21 , R ^C22 , and R ^C23 includes an aryl group having 6 to 10 carbon atoms (preferably 6 to 9, more preferably 6 to 8).

Specific examples of the aryl group include a phenyl group and a naphthyl group.
Among these, a phenyl group is preferred as the aryl group.

In addition, in general formula (2), each of the above-mentioned substituents represented by R ^C21 , R ^C22 , and R ^C23 also includes a group having a further substituent. Examples of this substituent include the atoms and groups exemplified above (eg, halogen atom, alkyl group, alkoxy group, aryl group, etc.).

In general formula (2), R ^C21 , R ^C22 , and R ^C23 are each independently a hydrogen atom or a carbon atom having 1 to 1 carbon atoms, especially from the viewpoint of forming a photosensitive layer (charge transport layer) with high charge transport ability. It is preferable that R ^C21 and R ^C23 represent a hydrogen atom, and R ^C22 represents an alkyl group having 1 to 10 carbon atoms (particularly a methyl group).

Specifically, the benzidine-based charge transport substance (CT2) is particularly preferably a charge transport substance represented by the following structural formula (2A) (exemplified compound (CT2-2)).

Specific examples of benzidine-based charge transport substances are shown below, but the present invention is not limited thereto.

The abbreviations in the above exemplary compounds have the following meanings. Moreover, the number attached before a substituent shows the substitution position with respect to a benzene ring.
・-CH ₃ : Methyl group ・-C ₂ H ₅ : Ethyl group ・-OCH ₃ : Methoxy group ・-OC ₂ H ₅ : Ethoxy group

Here, the proportion of the benzidine-based charge transport substance in the charge transport substance is preferably within the range of 20 to 80% by mass, more preferably within the range of 40 to 70% by mass.

As the charge transport substance, other charge transport substances other than the triphenylamine charge transport substance and the benzidine charge transport substance may be used in combination.

The mass ratio of the binder resin to the charge transport material in the charge transport layer is preferably in the range of 2:8 to 8:2, for example.
The content of the charge transport substance is preferably in the range of 20 to 80% by mass, more preferably in the range of 40 to 60% by mass, based on the entire charge transport layer.

Note that the mass ratio of the triphenylamine-based charge transport material to the benzidine-based charge transport material (triphenylamine-based charge transport material/benzidine-based charge transport material) is 2. /8 to 8/2 is preferable, and 3/7 to 5/5 is more preferable.

(binder resin)
Binder resins used for the charge transport layer include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, and chloride resin. Vinylidene-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N- Examples include vinylcarbazole and polysilane. Among these, polycarbonate resin or polyarylate resin is suitable as the binder resin. These binder resins may be used alone or in combination of two or more.

The binder resin is preferably a polycarbonate resin, and more preferably a polycarbonate resin containing a structural unit represented by the following general formula (PCA) and a structural unit represented by the following general formula (PCB).

In the general formulas (PCA) and (PCB), R ^P1 , R ^P2 , R ^P3 , and R ^P4 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, or a C 5 to 7 alkyl group. Represents a cycloalkyl group or an aryl group having 6 to 12 carbon atoms. X ^P1 represents a phenylene group, a biphenylene group, a naphthylene group, an alkylene group, or a cycloalkylene group.

In the general formulas (PCA) and (PCB), the alkyl groups represented by R ^P1 , R ^P2 , R ^P3 , and R ^P4 include straight-chain or branched alkyl groups having 1 to 6 carbon atoms (preferably 1 to 3 carbon atoms). Examples include alkyl groups of the form.

Specific examples of the linear alkyl group include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, and the like.

Specifically, the branched alkyl group includes an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, and a tert-hexyl group. etc.
Among these, as the alkyl group, lower alkyl groups such as methyl group and ethyl group are preferable.

In the general formulas (PCA) and (PCB), examples of the cycloalkyl group represented by R ^P1 , R ^P2 , R ^P3 , and R ^P4 include cyclopentyl, cyclohexyl, and cycloheptyl.

In the general formulas (PCA) and (PCB), examples of the aryl group represented by R ^P1 , R ^P2 , R ^P3 , and R ^P4 include a phenyl group, a naphthyl group, and a biphenylyl group.

In the general formulas (PCA) and ( ^PCB ), the alkylene group represented by Examples include alkylene groups.

Specific examples of linear alkylene groups include methylene group, ethylene group, n-propylene group, n-butylene group, n-pentylene group, n-hexylene group, n-heptylene group, n-octylene group, n- Examples include nonylene group, n-decylene group, n-undecylene group, n-dodecylene group, and the like.

Specifically, the branched alkylene group includes an isopropylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, an isopentylene group, a neopentylene group, a tert-pentylene group, an isohexylene group, a sec-hexylene group, and a tert-hexylene group. group, isoheptylene group, sec-heptylene group, tert-heptylene group, isooctylene group, sec-octylene group, tert-octylene group, isononylene group, sec-nonylene group, tert-nonylene group, isodecylene group, sec-decylene group, tert -decylene group, isoundecylene group, sec-undecylene group, tert-undecylene group, neooundecylene group, isododecylene group, sec-dodecylene group, tert-dodecylene group, neododecylene group and the like.
Among these, as the alkylene group, lower alkyl groups such as methylene group, ethylene group, butylene group are preferable.

In the general formulas (PCA) and (PCB), the cycloalkylene group represented by X ^P1 includes a cycloalkylene group having 3 to 12 carbon atoms (preferably 3 to 10 carbon atoms, more preferably 5 to 8 carbon atoms). It will be done.
Specific examples of the cycloalkylene group include a cyclopropylene group, a cyclopentylene group, a cyclohexylene group, a cyclooctylene group, and a cyclododecanylene group.
Among these, a cyclohexylene group is preferred as the cycloalkylene group.

In addition, in the general formulas (PCA) and (PCB), each of the above substituents represented by R ^P1 , R ^P2 , R ^P3 , R ^P4 , and X ^P1 also includes a group having a further substituent. Examples of this substituent include halogen atoms (e.g. fluorine atoms, chlorine atoms), alkyl groups (e.g. alkyl groups having 1 to 6 carbon atoms), cycloalkyl groups (e.g. cycloalkyl groups having 5 to 7 carbon atoms), alkoxy Examples include groups (eg, alkoxy groups having 1 to 4 carbon atoms), aryl groups (eg, phenyl groups, naphthyl groups, biphenylyl groups, etc.).

In the general formula (PCA), R ^P1 and R ^P2 each independently preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ^P1 and R ^P2 represent a hydrogen atom. is more preferable.
In the general formula (PCB), R ^P3 and R ^P4 each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and it is preferable that X ^P1 represents an alkylene group or a cycloalkylene group.

Specific examples of the BP polycarbonate resin include, but are not limited to, the following. In addition, in the exemplified compounds, pm and pn indicate the copolymerization ratio.

Here, in the polycarbonate resin, the content (copolymerization ratio) of the structural unit represented by the general formula (PCA) is preferably within the range of 5 to 95 mol% based on the total structural units constituting the polycarbonate resin, and From the viewpoint of increasing the abrasion resistance of the layer (charge transport layer), the amount is preferably within the range of 5 to 50 mol%, more preferably within the range of 15 to 30 mol%.

Specifically, in the above exemplary compounds of polycarbonate resin, pm and pn indicate the copolymerization ratio (molar ratio), and pm:pn = 95:5 to 5:95, 50:50 to 5:95. More preferably, the range is from 15:85 to 30:70.

When the polycarbonate resin is used in combination with another binder resin, the content of the other binder resin is preferably 10% by mass (preferably 5% by mass or less) based on the total binder resin.

Here, the viscosity average molecular weight of the binder resin (especially polycarbonate resin) is preferably within the range of 40,000 to 80,000, and from the viewpoint of stabilizing the coating liquid, it is preferably within the range of 40,000 to 60,000. preferable.
The viscosity average molecular weight of the binder resin (especially polycarbonate resin) is measured by the following method. 1 g of resin was uniformly dissolved in 100 cm ³ of methylene chloride, and its specific viscosity ηsp was measured using an Ubbelohde viscometer in a measurement environment of 25°C, and the relational expression ηsp/c = [η] + 0.45 [η] ² c was obtained. (However, c is the equation given by H. Schnell, which calculates the intrinsic viscosity [η] (cm ³ /g) from the concentration (g/cm ³ ), [η] = 1.23 × 10 ^-4 Mv ^0. The viscosity average molecular weight Mv is determined from the relational expression ⁸³ .

The content of the binder resin is, for example, preferably in the range of 10 to 90% by mass, more preferably in the range of 30 to 90% by mass, and in the range of 50 to 90% by mass, based on the total solid content of the charge transport layer. The inside is more preferable.

(Antioxidant)
In the present invention, it is preferable that the photosensitive layer contains an antioxidant.
An antioxidant is a substance that has the property of preventing or suppressing the action of oxygen on oxidizing substances existing inside or on the surface of the charge transport layer (photosensitive layer) under conditions such as light, heat, and electric discharge. .

Examples of the antioxidant include radical polymerization inhibitors, peroxide decomposers, and the like. Examples of the radical polymerization inhibitor include known antioxidants such as hindered phenol antioxidants, hindered amine antioxidants, diallylamine antioxidants, diallyldiamine antioxidants, and hydroquinone antioxidants. It will be done. Examples of peroxide decomposers include known organic sulfur-based (for example, thioether-based) antioxidants, phosphoric acid-based antioxidants, dithiocarbamate-based antioxidants, thiourea-based antioxidants, benzimidazole-based antioxidants, and the like. Antioxidants include:

Among these, radical polymerization inhibitors are preferred as antioxidants, and hindered phenol antioxidants and hindered amine antioxidants are particularly preferred. The antioxidant may be an antioxidant having two or more different skeletons having an antioxidant effect in one molecule (for example, an antioxidant having a hindered phenol skeleton and a hindered amine skeleton, etc.).
These antioxidants may be used alone or in combination of two or more.

The content of the antioxidant is 0 to 0.25 parts by mass, preferably 0 to 0.2 parts by mass, and more preferably 0 to 0.15 parts by mass, based on the total solid content of the charge transport layer.

Note that if the content of the antioxidant is low, a decrease in image density due to high-speed image formation can be easily suppressed, and if the content of the antioxidant is high, band-like image defects can be easily suppressed. Therefore, it is preferable to take these into account and adjust the content of the antioxidant.

(Other additives)
The charge transport layer may also contain other well-known additives.

(Formation of charge transport layer)
There are no particular restrictions on the formation of the charge transport layer, and well-known formation methods may be used. , by heating if necessary.

Examples of solvents for preparing the coating solution for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; and methylene chloride, chloroform, and ethylene chloride. Halogenated aliphatic hydrocarbons; common organic solvents such as cyclic or linear ethers such as tetrahydrofuran and ethyl ether; These solvents may be used alone or in combination of two or more.

Application methods for applying the charge transport layer forming coating liquid onto the charge generation layer include blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating. Usual methods such as coating methods can be used.

The thickness of the charge transport layer is, for example, preferably set within the range of 5 to 50 μm, more preferably within the range of 10 to 30 μm.

(Analysis of charge transport materials)
For analysis of the compound represented by general formula (1) or (2), the photosensitive layer was dissolved in an organic solvent (acetone), and each component was qualitatively determined by NMR and LC/MS measurements. Furthermore, the composition ratio of the charge transport material can be calculated by reverse phase HPLC/corona CAD measurement of the organic solvent (acetone) soluble content.

2.1.2. Charge Generation Layer The charge generation layer is, for example, a layer containing a charge generation substance and a binder resin. Further, the charge generation layer may be a deposited layer of a charge generation substance.

(charge generating substance)
Examples of the charge generating substance include azo pigments such as bisazo and trisazo; condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

Among these, in order to be compatible with laser exposure in the near-infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating substance. Specifically, for example, hydroxygallium phthalocyanine disclosed in JP-A-5-263007, JP-A-5-279591, etc.; chlorogallium phthalocyanine disclosed in JP-A-5-98181, etc.; Dichlorotin phthalocyanine disclosed in JP-A-140472, JP-A-5-140473 and the like; titanyl phthalocyanine disclosed in JP-A-4-189873 and the like are more preferred.

On the other hand, in order to be compatible with laser exposure in the near-ultraviolet region, charge-generating substances include condensed aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; Bisazo pigments disclosed in JP-A No. 2004-78147 and JP-A No. 2005-181992 are preferred.

The above-mentioned charge-generating substance may also be used when using an incoherent light source such as an LED or an organic EL image array, which has a central emission wavelength within the range of 450 to 780 nm, but from the viewpoint of resolution, the photosensitive layer is When used in a thin film of 20 μm or less, the electric field strength in the photosensitive layer becomes high, and a decrease in charging due to charge injection from the substrate tends to cause image defects called so-called black spots. This becomes noticeable when a charge-generating substance such as trigonal selenium or phthalocyanine pigment, which is a p-type semiconductor and tends to generate dark current, is used.

On the other hand, when n-type semiconductors such as condensed aromatic pigments, perylene pigments, and azo pigments are used as charge-generating substances, dark current is less likely to occur, and image defects called sunspots can be suppressed even if the film is made thin. . Examples of n-type charge generating substances include compounds (CG-1) to (CG-27) described in paragraphs [0288] to [0291] of JP-A No. 2012-155282. It is not limited.
Note that the n-type is determined by the polarity of the flowing photocurrent using the commonly used time-of-flight method, and the n-type is determined if it is easier to flow electrons as carriers than holes.

Among these, the charge generating substance is preferably a hydroxygallium phthalocyanine pigment, more preferably a V-type hydroxygallium phthalocyanine pigment, from the viewpoint of charge generation efficiency.
In particular, as hydroxygallium phthalocyanine pigments, for example, hydroxygallium phthalocyanine pigments having a maximum peak wavelength in the range of 810 to 839 nm have better dispersion in the spectral absorption spectrum in the wavelength range of 600 to 900 nm. It is preferable from the viewpoint of obtaining properties.

Further, it is preferable that the hydroxygallium phthalocyanine pigment having the maximum peak wavelength within the range of 810 to 839 nm has an average particle size within a specific range and a BET specific surface area within a specific range. Specifically, the average particle diameter is preferably 0.20 μm or less, more preferably within the range of 0.01 to 0.15 μm. On the other hand, the BET specific surface area is preferably 45 m ² /g or more, more preferably 50 m ² /g or more, and particularly preferably within the range of 55 to 120 m ² /g.

The average particle size is a volume average particle size (d50 average particle size) measured using a laser diffraction scattering particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.). Moreover, it is a value measured by a nitrogen substitution method using a BET type specific surface area measuring device (manufactured by Shimadzu Corporation: Flow Soap II2300).

The maximum particle size (maximum primary particle size) of the hydroxygallium phthalocyanine pigment is preferably 1.2 μm or less, more preferably 1.0 μm or less, and even more preferably 0.3 μm or less.

The hydroxygallium phthalocyanine pigment preferably has an average particle size of 0.2 μm or less, a maximum particle size of 1.2 μm or less, and a specific surface area value of 45 m ² /g or more.

The hydroxygallium phthalocyanine pigment has a Bragg angle (2θ±0.2°) of at least 7.3°, 16.0°, 24.9°, 28.0° in an X-ray diffraction spectrum using CuKα characteristic X-rays. It is preferable that it is a V type having a diffraction peak at .

One type of charge generating substance may be used alone, or two or more types may be used in combination.

(binder resin)
The binder resin used in the charge generating layer is selected from a wide variety of insulating resins, and the binder resin is selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. It's okay.
Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenols and aromatic dihydric carboxylic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide. Examples include resins, acrylic resins, polyacrylamide resins, polyvinylpyridine resins, cellulose resins, urethane resins, epoxy resins, casein, polyvinyl alcohol resins, polyvinylpyrrolidone resins, and the like. Here, "insulating" means that the volume resistivity is 10 ¹³ Ωcm or more.
These binder resins may be used alone or in combination of two or more.

Note that the blending ratio of the charge generating substance and the binder resin is preferably within the range of 10:1 to 1:10 in terms of mass ratio.

(Other additives)
The charge generation layer may also contain other well-known additives.

(Formation of charge generation layer)
There are no particular restrictions on the formation of the charge generation layer, and well-known formation methods may be used. and heat as necessary. Note that the charge generation layer may be formed by vapor deposition of a charge generation substance. Formation of the charge generation layer by vapor deposition is particularly suitable when a condensed aromatic pigment or perylene pigment is used as the charge generation substance.

Examples of the solvent for preparing the coating solution for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, and n-acetic acid. -butyl, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like. These solvents may be used alone or in combination of two or more.

As a method for dispersing particles (for example, a charge generating substance) in a coating liquid for forming a charge generating layer, for example, a media dispersing machine such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, a stirring machine, an ultrasonic dispersing machine, etc. Medialess dispersion machines such as , roll mills, and high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by penetrating fine channels under high pressure.
In addition, during this dispersion, it is effective to keep the average particle size of the charge generating substance in the coating liquid for forming a charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less. .

Examples of methods for applying the charge generation layer forming coating liquid onto the subbing layer (or onto the intermediate layer) include blade coating, wire bar coating, spray coating, dip coating, bead coating, and air knife coating. For example, conventional methods such as a coating method and a curtain coating method may be used.

The thickness of the charge generation layer is, for example, preferably set within the range of 0.1 to 5.0 μm, more preferably within the range of 0.2 to 2.0 μm.

2.1.3. Conductive support Examples of the conductive support include metal plates and metal drums containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). , and metal belts. Examples of conductive supports include paper, resin films, and belts coated with, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. etc. can also be mentioned. Here, "conductivity" means that the volume resistivity is less than 10 ¹³ Ωcm.

When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive support has a center line average roughness Ra of 0.04 μm or more and 0.05 μm or more for the purpose of suppressing interference fringes that occur when laser light is irradiated. It is preferable that the surface is roughened to 5 μm or less. Note that when non-interfering light is used as a light source, surface roughening to prevent interference fringes is not particularly necessary, but it is suitable for longer life since it suppresses the occurrence of defects due to unevenness on the surface of the conductive support.

Examples of surface roughening methods include wet honing, which is performed by suspending an abrasive in water and spraying it on the conductive support, and continuous grinding by pressing the conductive support against a rotating grindstone. Examples include centerless grinding and anodizing.

The surface roughening method involves dispersing conductive or semiconductive powder in a resin to form a layer on the surface of the conductive support without roughening the surface of the conductive support. , and a method of roughening the surface by using particles dispersed in the layer. As the layer for surface roughening, it is also possible to use a subbing layer, which will be described later.

Surface roughening treatment by anodic oxidation involves forming an oxide film on the surface of a conductive support by using a metal (for example, aluminum) conductive support as an anode and performing anodic oxidation in an electrolyte solution. Examples of the electrolyte solution include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodic oxidation is chemically active as it is, is easily contaminated, and has large resistance fluctuations depending on the environment. Therefore, for a porous anodic oxide film, the micropores of the oxide film are blocked by volume expansion caused by a hydration reaction with pressurized steam or boiling water (metal salts such as nickel may be added) to achieve more stable hydrated oxidation. It is preferable to perform a sealing process to convert the material into a material.

The thickness of the anodic oxide film is preferably 0.3 to 15 μm, for example. When the film thickness is within the above range, barrier properties against injection tend to be exhibited, and increases in residual potential due to repeated use tend to be suppressed.

The conductive support may be treated with an acidic treatment liquid or treated with boehmite.
The treatment with the acidic treatment liquid is carried out, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The blending ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment solution is, for example, phosphoric acid in the range of 10 to 11% by mass, chromic acid in the range of 3 to 5% by mass, and hydrofluoric acid in the range of 0.5 to 2% by mass. %, and the total concentration of these acids is preferably in the range of 13.5 to 18% by weight. The treatment temperature is preferably 42 to 48°C, for example. The thickness of the coating is preferably 0.3 to 15 μm.

The boehmite treatment is carried out, for example, by immersion in pure water at 90 to 100°C for 5 minutes to 60 minutes, or by contacting heated steam at 90 to 120°C for 5 minutes to 60 minutes. The thickness of the coating is preferably 0.1 to 5 μm. This can be further anodized using an electrolyte solution with low film solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate. good.

2.1.4. Subbing layer The subbing layer is, for example, a layer containing inorganic particles and a binder resin.
Examples of the inorganic particles include inorganic particles having a powder resistance (volume resistivity) of 10 ² to 10 ¹¹ Ωcm.
Among these, as the inorganic particles having the above-mentioned resistance value, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles are preferable, and zinc oxide particles are particularly preferable.

The specific surface area of the inorganic particles measured by the BET method is preferably 10 m ² /g or more, for example.
The volume average particle size of the inorganic particles is, for example, within the range of 50 to 2000 nm (preferably within the range of 60 to 1000 nm).

The content of the inorganic particles is, for example, preferably in the range of 10 to 80% by mass, more preferably in the range of 40 to 80% by mass, based on the binder resin.

The inorganic particles may be surface-treated. Two or more types of inorganic particles with different surface treatments or different particle sizes may be used as a mixture.

Examples of the surface modifier include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, and the like. In particular, silane coupling agents are preferred, and silane coupling agents having an amino group are more preferred.

Examples of the silane coupling agent having an amino group include 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-amino Examples include, but are not limited to, propylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and the like.

Two or more types of silane coupling agents may be used in combination. For example, a silane coupling agent having an amino group and another silane coupling agent may be used together. Examples of other silane coupling agents include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glyoxypropyl-tris(2-methoxyethoxy)silane. Sidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-( Examples include, but are not limited to, aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane. It's not a thing.

The surface treatment method using the surface modifier may be any known method, and may be either a dry method or a wet method.

The amount of surface modifier to be treated is preferably within the range of 0.5 to 10% by mass based on the inorganic particles, for example.

Here, it is preferable for the undercoat layer to contain an electron-accepting compound (acceptor compound) together with inorganic particles, from the viewpoint of improving long-term stability of electrical properties and carrier blocking properties.

Examples of electron-accepting compounds include quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, etc. Fluorenone compound; 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4- Oxadiazole compounds such as oxadiazole, 2,5-bis(4-diethylaminophenyl)-1,3,4oxadiazole; xanthone compounds; thiophene compounds; 3,3',5,5'tetra- Examples include electron transporting substances such as diphenoquinone compounds such as t-butyldiphenoquinone;
In particular, as the electron-accepting compound, a compound having an anthraquinone structure is preferred. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound, etc. are preferable, and specifically, for example, anthraquinone, alizarin, quinizarin, anthralphine, purpurin, etc. are preferable.

The electron-accepting compound may be contained in the undercoat layer in a dispersed manner with the inorganic particles, or may be contained in a state attached to the surface of the inorganic particles.

Examples of the method for attaching the electron-accepting compound to the surface of the inorganic particles include a dry method and a wet method.

In the dry method, for example, while stirring inorganic particles with a mixer with a large shearing force, an electron-accepting compound is dropped directly or dissolved in an organic solvent, and the electron-accepting compound is sprayed with dry air or nitrogen gas. This method attaches to the surface of inorganic particles. When dropping or spraying the electron-accepting compound, it is preferable to do so at a temperature below the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be performed at a temperature of 100° C. or higher. There are no particular restrictions on the baking temperature and time as long as the electrophotographic properties can be obtained.

In the wet method, for example, an electron-accepting compound is added while dispersing inorganic particles in a solvent using stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and after stirring or dispersion, the solvent is removed and the electron-accepting compound is added. This is a method in which a receptive compound is attached to the surface of an inorganic particle. The solvent is removed by, for example, filtration or distillation. After removing the solvent, baking may be further performed at 100° C. or higher. There are no particular limitations on the baking temperature and time as long as the electrophotographic properties can be obtained. In the wet method, the water contained in the inorganic particles may be removed before adding the electron-accepting compound, examples of which include removing the water while stirring and heating it in a solvent, and removing it by azeotroping with the solvent. Can be mentioned.

Note that the electron-accepting compound may be attached before or after the inorganic particles are subjected to the surface treatment with the surface modifier, or may be carried out simultaneously with the electron-accepting compound and the surface treatment with the surface modifier.

The content of the electron-accepting compound is, for example, preferably in the range of 0.01 to 20% by mass, preferably in the range of 0.01 to 10% by mass, based on the inorganic particles.

Examples of binder resins used in the undercoat layer include acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, and unsaturated polyester resins. , methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane Known materials include known polymer compounds such as resins, alkyd resins, and epoxy resins; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; and silane coupling agents.
Examples of the binder resin used in the undercoat layer include charge transporting resins having a charge transporting group, conductive resins (eg, polyaniline, etc.), and the like.

Among these, resins that are insoluble in the coating solvent of the upper layer are suitable as the binder resin for the undercoat layer, and in particular, urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, and unsaturated polyester resins are suitable. , thermosetting resins such as alkyd resins and epoxy resins; cured with at least one resin selected from the group consisting of polyamide resins, polyester resins, polyether resins, methacrylic resins, acrylic resins, polyvinyl alcohol resins, and polyvinyl acetal resins. Resins obtained by reaction with agents are preferred.
When using a combination of two or more of these binder resins, the mixing ratio is determined as necessary.

The undercoat layer may contain various additives to improve electrical properties, environmental stability, and image quality.
Examples of additives include known materials such as polycyclic condensation type, azo type electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. It will be done. The silane coupling agent is used for surface treatment of inorganic particles as described above, but it may also be added to the undercoat layer as an additive.

Examples of the silane coupling agent as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3- Glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2- Examples include (aminoethyl)-3-aminopropylmethylmethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

Examples of zirconium chelate compounds include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, acetoacetate ethyl zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, Zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide, and the like.

Examples of titanium chelate compounds include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, and titanium lactate ammonium salt. , titanium lactate, titanium lactate ethyl ester, titanium triethanolaminate, polyhydroxytitanium stearate, and the like.

Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, aluminum tris (ethylacetoacetate), and the like.

These additives may be used alone or as a mixture or polycondensate of multiple compounds.

The undercoat layer preferably has a Vickers hardness of 35 or more.
The surface roughness (ten-point average roughness) of the undercoat layer ranges from 1/(4n) (n is the refractive index of the upper layer) to 1/2 of the exposure laser wavelength λ used to suppress moiré images. It is good to have it adjusted to
Resin particles or the like may be added to the undercoat layer to adjust the surface roughness. Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. Further, the surface of the undercoat layer may be polished to adjust the surface roughness. Examples of the polishing method include buffing, sandblasting, wet honing, and grinding.

There are no particular restrictions on the formation of the undercoat layer, and well-known formation methods may be used. and heat as necessary.

As the solvent for preparing the coating solution for forming the undercoat layer, known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, and ether solvents can be used. Examples include solvents and ester solvents.
Specific examples of these solvents include methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, Common organic solvents include n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

Examples of methods for dispersing inorganic particles when preparing a coating solution for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibrating ball mill, an attriter, a sand mill, a colloid mill, and a paint shaker.

Examples of methods for applying the coating solution for forming an undercoat layer onto the conductive support include blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating. Ordinary methods such as the method can be mentioned.

The thickness of the undercoat layer is, for example, preferably set within a range of 0.5 to 20 μm or more, more preferably 2 to 15 μm.

2.1.5. Intermediate layer Although not shown, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.
The intermediate layer is, for example, a layer containing resin. Examples of the resin used for the intermediate layer include acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, Examples include polymeric compounds such as polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, and melamine resin.
The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.
The compounds used in these intermediate layers may be used alone or as a mixture or polycondensate of a plurality of compounds.

Among these, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

There are no particular restrictions on the formation of the intermediate layer, and well-known formation methods may be used. This is done by heating according to the conditions.
As a coating method for forming the intermediate layer, conventional methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating can be used.

The thickness of the intermediate layer is preferably set within a range of 0.1 to 3 μm, for example. Note that the intermediate layer may be used as a subbing layer.

2.1.6. Others: Protective layer The electrophotographic photoreceptor according to the present invention preferably further includes a protective layer. The protective layer is prepared by adding a polymerizable compound, metal oxide particles, if necessary a polymerization initiator, a specific radical scavenger, and other components such as a charge transport substance and fine resin particles to a known solvent to form a coating solution ( (hereinafter also referred to as "coating liquid for forming a protective layer"), this coating liquid for forming a protective layer is applied to the outer peripheral surface of the charge transport layer to form a coating film, this coating film is dried, and A protective layer can be formed by polymerizing and curing the polymerizable compound component in the coating film by irradiating it with actinic rays such as or electron beams.

As the solvent used to form the protective layer, any solvent can be used as long as it can dissolve or disperse the polymerizable compound, metal oxide fine particles, and specific charge transporting substance, such as methanol, ethanol, n-propyl, etc. Alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methylene chloride, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1 , 3-dioxolane, pyridine and diethylamine, but are not limited to these.

As a method for applying the coating liquid for forming a protective layer, known methods such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, a slide hopper method, and a circular slide hopper method can be used. There are several methods.
It is preferable to apply the protective layer forming coating liquid by a slide hopper method using a circular slide hopper coating device from the viewpoint of preventing the protective layer from dissolving as much as possible. It can be applied by any method.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without restriction. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, etc. can be used.
Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is preferably within the range of 5 to 500 mJ/cm ² , more preferably within the range of 5 to 100 mJ/cm ² .

The power of the lamp is preferably in the range of 0.1 to 5 kW, more preferably in the range of 0.5 to 4 kW, even more preferably in the range of 0.5 to 3 kW.
The irradiation time to obtain the required dose of active radiation is preferably 0.1 seconds to 10 minutes, and more preferably 0.1 seconds to 5 minutes from the viewpoint of work efficiency.
In the step of forming the protective layer, drying can be performed before or after irradiation with actinic rays, or during irradiation with actinic rays, and the timing of drying can be appropriately selected by combining these.

2.2. Method for Manufacturing Electrophotographic Photoreceptor The photoreceptor of the present invention is preferably manufactured by a manufacturing method including the following steps, although it is not particularly limited.
Step (1): If necessary, a step of forming a subbing layer by applying a coating liquid for forming a subbing layer on the outer peripheral surface of the conductive support and drying it.
Step (2): A coating solution for forming a charge generation layer is applied to the outer peripheral surface of the conductive support or the outer peripheral surface of the subbing layer formed on the conductive support in step (1), and dried. forming a charge generation layer by;
Step (3): forming a charge transport layer by applying a coating liquid for forming a charge transport layer on the outer peripheral surface of the charge generation layer formed on the undercoat layer and drying it;
Step (4): A step of forming a protective layer by applying a coating liquid for forming a protective layer on the outer peripheral surface of the charge transport layer formed on the charge generating layer, polymerizing and curing the coating liquid.

The concentration of each component in the coating liquid for forming each layer is appropriately selected according to the layer thickness and production rate of each layer.
In the coating liquid for forming each layer, an ultrasonic dispersion machine, a ball mill, a sand mill, a homo mixer, etc. can be used as a means for dispersing particles such as conductive particles and metal oxide particles and charge generating substances. However, it is not limited to these.
The method of applying the coating liquid to form each layer is not particularly limited, but examples include dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method, circular Known methods such as the slide hopper method may be used.
The method for drying the coating film can be appropriately selected depending on the type of solvent and layer thickness, but thermal drying is preferred.

3. Toner for developing an electrostatic image The toner for developing an electrostatic image (hereinafter also simply referred to as "toner") of the present invention comprises toner base particles comprising at least a resin (hereinafter also referred to as a binder resin) and a colorant; Contains external additives. In addition to the binder resin and the colorant, the toner base particles according to the present invention may contain various internal additives such as a release agent, a charge control agent, or a surfactant, if necessary.

In the present invention, "toner" refers to an aggregate of "toner particles", and the toner particles refer to the above-mentioned toner base particles to which an external additive is added. Furthermore, in the following description, toner base particles and toner particles are also simply referred to as "toner particles" when there is no need to particularly distinguish between them.

The electrostatic image developing toner according to the present invention is characterized in that it contains titanic acid compound particles having a number average primary particle diameter of 10 to 80 nm as an external additive.

It is preferable that the number average particle diameter of the primary particles of the titanate compound particles is within the above range from the viewpoint of suppressing embedding and detachment of the titanate compound particles, and from the viewpoint of lowering the electrical resistance, metal elements other than titanium are preferably used. It is preferable to include.
The titanate compound particles according to the present invention further contain one or more elements selected from lanthanum, tin, silicon, magnesium, strontium, calcium, or barium , thereby reducing electrical resistance .

The titanate compound particles are strontium titanate particles, calcium titanate particles, or barium titanate particles, and the particle size can be easily controlled during production.

It is preferable that the titanate compound particles further contain a lanthanum element from the viewpoint of ease of production and reduction in electrical resistance.
Further, by including lanthanum, the particle shape becomes a slightly rounded shape rather than a rectangular parallelepiped, which is preferable from the viewpoint of suppressing embedding in toner and suppressing photoreceptor deterioration.

The toner according to the present invention contains silica particles having a number average diameter of primary particles in the range of 5 to 40 nm as an external additive.
Silica particles with a small diameter and a sharp particle size distribution have good dispersibility on the toner surface.
Moreover, since it has strong negative chargeability, it electrostatically attracts titanate compound particles, which are rather positively chargeable.
These things further improve the dispersibility of the titanic acid compound onto the surface of the toner particles.

Spherical silica particles manufactured by the sol-gel method have a uniform particle size (narrow particle size distribution, that is, monodisperse) compared to fumed silica, which is a common manufacturing method. preferable. Therefore, it is preferable that the coefficient of variation of the particle size distribution of the silica particles is 20% or less.
The external additives and the like will be explained in detail below.

3.1. External Additive The toner for developing an electrostatic image according to the present invention contains titanic acid compound particles having a number average primary particle diameter of 10 to 80 nm as an external additive. Such external additives are added (externally added) to the surface of the toner base particles, and the toner for electrostatic development according to the present invention contains inorganic fine particles. Further, the inorganic fine particles include a titanic acid compound that has been hydrophobized with a surface modifier.

(Titanic acid compound)
Examples of titanic acid compounds that can be used in the present invention include compounds represented by the following general formula called metatitanates, which are produced from titanium (IV) oxide and other metal oxides or metal carbonates. It is representative.
General formula: _{MI2TiO3 or MIITiO3}
(In the formula, MI represents a monovalent metal atom, and MII represents a divalent metal atom.)

The titanic acid compound that can be used in the present invention is preferably a titanic acid compound having a structure bonded to a divalent metal atom represented by MIITiO ₃ . Specific examples of titanate compounds bonded to divalent metal atoms include calcium titanate (CaTiO ₃ ), magnesium titanate (MgTiO ₃ ), strontium titanate (SrTiO ₃ ), and barium titanate (BaTiO ₃ ). etc. Among these titanate compounds bonded to divalent metal atoms, calcium titanate (CaTiO ₃ ) is preferred from the viewpoint of environmental impact and the viewpoint of maintaining the amount of charge at a constant level over a long period of time.

The titanic acid compound that can be used in the present invention can be produced by a known method. As a method for producing a titanic acid compound that can be used in the present invention, there is, for example, a method for producing it via a titanium (IV) oxide compound TiO ₂ .H ₂ O in the form of a hydrate called metatitanic acid.

This method is a method in which the titanium (IV) oxide compound is reacted with a metal carbonate or metal oxide such as calcium carbonate, and then a titanate compound represented by calcium titanate is produced by firing treatment. Note that a hydrolyzate of titanium oxide such as metatitanic acid is also called a mineral acid peptized product, and has the form of a liquid in which titanium oxide particles are dispersed. A water-soluble metal carbonate or metal oxide is added to the mineral acid peptized product made of this titanium oxide hydrolyzate, and the mixture is heated to 50°C or higher and reacted while adding an alkaline aqueous solution to form a titanate compound. is produced.

Metatitanic acid, which is one of the representative examples of mineral acid peptized products, has a sulfite SO ₃ content of 1.0% by mass or less, preferably 0.5% by mass or less, and has a pH of 0.8 to 1.5 with hydrochloric acid. It has been peptized and adjusted to

As the alkaline aqueous solution used for producing the titanic acid compound, a caustic alkaline aqueous solution typified by a sodium hydroxide aqueous solution is preferable. Further, examples of the compound to be reacted with the hydrolyzate of titanium oxide include nitric acid compounds, carbonate compounds, chloride compounds, etc. such as strontium, magnesium, calcium, barium, aluminum, zirconium, and sodium.

In the manufacturing process of titanic acid compounds, the ratio of addition of titanium oxide hydrates or hydrolysates and metal oxides, etc., the concentration of titanium oxide hydrates and hydrolysates during the reaction, the temperature and addition when adding aqueous alkaline solutions, etc. The particle size of the titanic acid compound can be controlled by adjusting the speed and the like. Furthermore, in order to prevent the formation of carbonate compounds in the reaction step, it is preferable to carry out the reaction under a nitrogen gas atmosphere.

The higher the temperature at which the alkaline aqueous solution is added, the more crystalline it can be obtained, but a temperature within the range of 50 to 101°C is suitable for practical use. Additionally, the addition rate of the alkaline aqueous solution tends to affect the particle size of the titanate compound obtained; the slower the addition rate, the larger the particle size of the titanate compound, and the faster the addition rate, the smaller the particle size. tends to form. The rate of addition of the alkaline aqueous solution is 0.001 to 1.0 equivalent/hour, preferably 0.005 to 0.5 equivalent/hour, based on the raw material, and can be adjusted as appropriate depending on the desired particle size. be. The addition rate of the alkaline aqueous solution can also be changed during the process depending on the purpose.

[Surface modifier]
In the present invention, for the titanic acid compound used as external additive particles, general silane coupling agents, silicone oils, fatty acids, fatty acid metal salts, and the like can be used as surface modifiers.

Examples of the silane coupling agent include chlorosilane, alkoxysilane, silazane, and special silylation agents. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, Methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N,O-(bistrimethylsilyl)acetamide, N,N-bis (trimethylsilyl)urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ Typical examples include -glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.

Specific examples of silicone oils include organosiloxane oligomers, octamethylcyclotetrasiloxane, cyclic compounds such as decamethylcyclopentasiloxane, tetramethylcyclotetrasiloxane, and tetravinyltetramethylcyclotetrasiloxane; Mention may be made of branched organosiloxanes. Further, a highly reactive silicone oil in which a modified group is introduced into a side chain, one end, both ends, one end of a side chain, both ends of a side chain, or at least a modified end may be used. Types of modifying groups include, but are not limited to, alkoxy, carboxyl, carbinol, higher fatty acid modification, phenol, epoxy, methacryl, and amino. Further, for example, silicone oil having several types of modification groups such as amino/alkoxy modification may be used. Further, dimethyl silicone oil, these modified silicone oils, and furthermore, other surface modifiers may be mixed or treated in combination.

As the surface modifier, a silane coupling agent is preferred, and a silane coupling agent represented by the following formula (1) is more preferred.
Formula (1): X-Si(OR) ₃
(In the formula, X represents an alkyl group having 4 to 12 carbon atoms, and R represents a methyl group or an ethyl group.)

The silane coupling agent represented by the above formula (1) is a silane coupling agent having an alkyl chain having 4 to 12 carbon atoms. When the silane coupling agent is used, it is possible to reduce the number of hydroxyl groups on the surface of the titanic acid compound due to the reactive group of the silane coupling agent. Furthermore, since the titanate compound comes to have a hydrophobic alkyl chain, the effect of suppressing the leakage of the charge amount is further exhibited. If the number of carbon atoms in R in formula (1) is 4 or more, the amount of carbon in the titanate compound can be adjusted to have the function of suppressing charging leakage, and if the number of carbon atoms is 12 or less, If so, it is possible to prevent aggregation due to entanglement of long alkyl chains and improve dispersibility when externally added to the toner surface. More preferably, R has 4 to 8 carbon atoms.

Specific examples of the silane coupling agent represented by formula (1) include isobutyltrimethoxysilane and octyltrimethoxysilane.

[Surface modification method]
Surface modification methods include, for example, dry methods such as spray drying in which a modifier or a solution containing a modifier is sprayed onto particles suspended in a gas phase, and immersing particles in a solution containing a modifier. Examples include a wet method in which the modifier is mixed with the particles using a mixer, and a mixing method in which the modifier and particles are mixed using a mixer.

(Number average diameter of primary particles of titanate compound)
The number average diameter of the primary particles of the titanic acid compound as an external additive is determined by adding (dispersing) the external additive to the toner particles, and then measuring 100 primary particles of the external additive using a scanning electron microscope "JSM-7401F". (manufactured by JEOL Ltd.) at a magnification of 40,000 times, the longest diameter and the shortest diameter of each particle are measured by image analysis of the primary particles, and the equivalent sphere diameter is determined from this intermediate value. Then, the average of the 100 measured primary particle diameters is defined as the number average primary particle diameter.

[Inorganic fine particles other than titanate compounds, organic fine particles, lubricants, etc.]
The external additive may contain inorganic fine particles, organic fine particles, and lubricants other than the titanic acid compound described above, as long as the effect of using the titanic acid compound is not impaired.

Examples of inorganic fine particles other than titanate compound fine particles include silica particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, Includes manganese oxide particles, boron oxide particles, etc. The inorganic fine particles may be hydrophobized using a known silane coupling agent, silicone oil, or other surface modifier, if necessary. Further, the size of the inorganic fine particles is preferably within the range of 20 to 500 nm, more preferably within the range of 70 to 300 nm in terms of number average primary particle diameter.

As the organic fine particles, organic fine particles made of a homopolymer of styrene or methyl methacrylate or a copolymer thereof can be used. The size of the organic fine particles is about 10 to 2000 nm in number average primary particle diameter, and the particle shape is, for example, spherical.

The above-mentioned lubricant is used for the purpose of further improving cleaning properties and transfer properties. Examples of the above-mentioned lubricants include metal salts of higher fatty acids, more specifically salts of stearic acid such as zinc, aluminum, copper, magnesium, and calcium; oleic acid of zinc, manganese, iron, copper, and magnesium. salts of palmitic acid such as zinc, copper, magnesium, calcium, etc.; salts of linoleic acid such as zinc, calcium, etc.; salts of ricinoleic acid such as zinc, calcium, etc. The size of the lubricant is preferably within the range of 0.3 to 20 μm, more preferably within the range of 0.5 to 10 μm, in volume-based median diameter (volume average particle size).

The content of the titanic acid compound fine particles in the toner particles is preferably within the range of 0.1 to 10.0 parts by mass based on 100 parts by mass of the toner particles. When using external additives other than the titanic acid compound fine particles, the total amount of the external additives (that is, the total amount of the titanic acid compound fine particles and other external additives) is preferably within the above range.

The external additive can be added to the toner base particles using various known mixing devices such as a turbular mixer, a Henschel mixer, a Nauta mixer, and a V-type mixer.

(Types of titanate compounds, metals contained in titanate compounds)
The metals contained in titanic acid compounds can be detected using, for example, a scanning electron microscope (SEM) "JSM-7401F" (manufactured by JEOL Ltd.) and an energy dispersive X-ray spectrometer (EDS) "JED-2300" (manufactured by JEOL Ltd.). It can be determined using a built-in device.

Specifically, it can be identified by performing element mapping on the external additive on the surface of the toner particles and determining the elements that are simultaneously detected in the external additive particles in which the titania element is detected.
EDS conditions were acceleration voltage: 20 kV, irradiation current: 2.56 nA, and PHA mode: T3.

(Method for measuring circularity of titanate compound particles)
To measure the circularity of titanic acid compounds, 100 titanic acid compounds were photographed at 40,000x magnification using a scanning electron microscope "JSM-7401F" (manufactured by JEOL Ltd.), and the photographic images were scanned using a scanner. This is done by importing and analyzing the image using an image processing and analysis device "LUZEX (registered trademark) AP" (manufactured by Nireco Co., Ltd.).

After determining the equivalent circle diameter and perimeter from the analyzed image, the circularity of each titanate compound is determined according to the following formula (1), and these are averaged.

Formula (1): Circularity = Circle equivalent diameter Perimeter length / Perimeter length = [2 × (Aπ) 1/2] / PM
In the above formula, A represents the projected area of the titanate compound, and PM represents the circumferential length of the titanate compound. When the circularity is 1.0, it is a true sphere, and the lower the number, the more uneven the outer periphery, and the higher the degree of irregularity.

(Method for measuring particle size of toner particles)
The number average particle diameter of the primary particles is determined by adding (dispersing) the external additive to the toner particles, and then examining 100 primary particles of the external additive using a scanning electron microscope "JSM-7401F" (manufactured by JEOL Ltd.). ), the longest diameter and shortest diameter of each particle are measured by image analysis of the primary particles, and the equivalent sphere diameter is determined from this intermediate value. Then, the average of the 100 measured primary particle diameters is defined as the number average particle diameter of the primary particles.

The coefficient of variation of the particle size distribution is calculated using the following formula from the number average particle diameter of the primary particles determined above.

Coefficient of variation = ((standard deviation of number average particle diameter of primary particles)/(number average particle diameter of primary particles)) x 100 (%)

In addition, the "spherical shape" of spherical particles means that the degree of sphericity is 0.6 or more. More preferably, the degree of sphericity is 0.8 or more. In the present invention, the degree of sphericity is Wadell's true degree of sphericity. That is, the degree of sphericity is expressed by the following formula (A).

Formula (A) Degree of sphericity = (Surface area of a sphere with the same volume as the actual particle) / (Surface area of the actual particle)

Here, "the surface area of a sphere having the same volume as the actual particle" can be determined by arithmetic calculation from the number average particle diameter determined by the method below. Further, the "actual particle surface area" can be substituted with the BET specific surface area determined using the "powder specific surface area measuring device SS-100" (manufactured by Shimadzu Corporation).

3.2. Binder Resin The toner base particles according to the present invention preferably contain an amorphous resin and a crystalline resin, and the amorphous resin is more preferably a polyester resin or a vinyl resin. Further, the toner base particles according to the present invention contain a colorant, and may further contain other components such as a release agent (wax) and a charge control agent, if necessary.

In the present invention, it is preferable that the amorphous resin be contained in the range of 50 to 95% by mass and the crystalline resin be contained in the range of 5 to 30% by mass based on the entire binder resin.

<Crystalline resin>
In the present invention, a crystalline resin refers to a resin that does not show a step-like endothermic change but has a clear endothermic peak in differential scanning calorimetry (DSC). Specifically, a clear endothermic peak refers to a peak whose half-value width is within 15°C when measured at a temperature increase rate of 10°C/min in differential scanning calorimetry (DSC). do.

The melting point Tmc of the crystalline resin is preferably 60° C. or higher from the viewpoint of obtaining sufficient high-temperature storage stability, and preferably 85° C. or lower from the viewpoint of obtaining sufficient low-temperature fixability.

The melting point Tmc of the crystalline resin can be measured by DSC. Specifically, 0.5 mg of a sample of crystalline resin was sealed in an aluminum pan "KITNO. The temperature is raised from 0° C. to 200° C. at a heating rate of 200° C., and the temperature at the top of the endothermic peak in the endothermic curve obtained is measured as the melting point (Tmc) of the crystalline resin.

The content of the crystalline resin with respect to the toner base particles is preferably within the range of 5 to 30% by mass, and more preferably within the range of 7 to 20% by mass, from the viewpoint of obtaining sufficient low-temperature fixability. .

When the content is 5% by mass or more, a sufficient plasticizing effect is obtained and low-temperature fixing properties are sufficient. Further, when the content is 20 mass or less, the toner has sufficient thermal stability and stability against physical stress.

Crystalline resins include, but are not particularly limited to, polyolefin resins, polydiene resins, and polyester resins. Among these, crystalline polyester resins are preferred from the viewpoint of obtaining sufficient low-temperature fixability and gloss uniformity, and from the viewpoint of ease of use.

Further, the number average molecular weight (Mn) of the crystalline resin is preferably within the range of 2,500 to 5,000, more preferably within the range of 3,000 to 4,500. By setting it within these ranges, the solution viscosity of the crystalline resin can be adjusted to the above-mentioned preferred range. In addition, the strength of the fixed image will not be insufficient, and the crystalline resin will not be crushed during stirring of the developer, and the glass transition temperature Tg of the toner will decrease due to excessive plasticizing effect, resulting in a decrease in the thermal stability of the toner. There's nothing to do. In addition, sharp melting properties are developed and low temperature fixing becomes possible.

The above Mn and weight average molecular weight Mw can be determined from the molecular weight distribution measured by gel permeation chromatography (GPC) as described below.

The measurement sample was added to tetrahydrofuran (THF) to a concentration of 1 mg/mL, dispersed for 5 minutes using a roll mill at room temperature, and then processed through a membrane filter with a pore size of 0.2 μm to prepare a sample solution. . Using a GPC device HLC-8320GPC EcoSEC (manufactured by Tosoh Corporation) and columns TSKgel guardcolumn SuperHZ-L + TSKgel SuperHZM-M triple series (manufactured by Tosoh Corporation), tetrahydrofuran was used as a carrier solvent at a flow rate of 0.5°C while maintaining the column temperature at 40°C. The flow rate was 35 mL/min. Inject 50 μL of the prepared sample solution into the GPC device along with the carrier solvent, detect the sample using a refractive index detector (RI detector), and use a calibration curve measured using monodisperse polystyrene standard particles. , the molecular weight distribution of the sample was calculated. The calibration curve has molecular weights of 6×10 ² , 2.1×10 ³ , 4×10 ³ , 1.75×10 ⁴ , 5.1×10 ⁴ , 1.1×10 ⁵ , and 3.9×10 It was created by measuring 10 polystyrene standard particles (manufactured by Pressure Chemical Co.) having particle sizes of ⁵ , 8.6×10 ⁵ , 2×10 ⁶ , and 4.48×10 ⁶ .

A crystalline polyester resin is obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid) and a divalent or higher alcohol (polyhydric alcohol).

Examples of polycarboxylic acids include dicarboxylic acids. The dicarboxylic acid may be one or more types, preferably an aliphatic dicarboxylic acid, and may further contain an aromatic dicarboxylic acid. The aliphatic dicarboxylic acid is preferably a linear type from the viewpoint of improving the crystallinity of the crystalline polyester.

Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid. Acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (dodecanedioic acid), 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1, Included are 18-octadecanedicarboxylic acid, lower alkyl esters thereof, and acid anhydrides thereof. Among these, aliphatic dicarboxylic acids having 6 to 16 carbon atoms are preferred, and aliphatic dicarboxylic acids having 10 to 14 carbon atoms are more preferred, from the viewpoint of easily achieving both low-temperature fixability and transferability.

Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, t-butyl isophthalic acid, 2,6-naphthalenedicarboxylic acid and 4,4'-biphenyldicarboxylic acid. Among these, terephthalic acid, isophthalic acid, or t-butyl isophthalic acid is preferred from the viewpoint of easy availability and emulsification.

The content of the aliphatic dicarboxylic acid-derived structural units relative to the dicarboxylic acid-derived structural units in the crystalline polyester resin is preferably 50 mol% or more, from the viewpoint of ensuring sufficient crystallinity of the crystalline polyester. It is more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 100 mol%.

Examples of polyhydric alcohol components include diols. The diol may be one or more types, preferably an aliphatic diol, and may further contain other diols. The aliphatic diol is preferably a linear type from the viewpoint of improving the crystallinity of the crystalline polyester.

Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18- Includes octadecanediol and 1,20-eicosandiol. Among these, aliphatic diols having 2 to 120 carbon atoms are preferred, and aliphatic diols having 4 to 10 carbon atoms are more preferred, from the viewpoint of easily achieving both low-temperature fixability and transferability.

Examples of other diols include diols with double bonds and diols with sulfonic acid groups. Specifically, examples of diols having double bonds include 2-butene-1,4-diol, 3-hexene-1,6-diol, and 4-octene-1,8-diol.

The content of aliphatic diol-derived structural units relative to diol-derived structural units in the crystalline polyester resin is 50 mol% or more from the viewpoint of improving the low-temperature fixing properties of the toner and the glossiness of the finally formed image. It is preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 100 mol%.

The ratio of the above diol and the above dicarboxylic acid in the monomer of the crystalline polyester resin is 2.0/in the equivalent ratio [OH]/[COOH] of the hydroxy group [OH] of the diol and the carboxy group [COOH] of the dicarboxylic acid. It is preferably within the range of 1.0 to 1.0/2.0, more preferably within the range of 1.5/1.0 to 1.0/1.5, and 1.3/1 It is particularly preferably within the range of .0 to 1.0/1.3.

The crystalline polyester resin can be synthesized by polycondensing (esterifying) the polyhydric carboxylic acid and polyhydric alcohol using a known esterification catalyst.

The catalyst that can be used to synthesize the crystalline polyester resin may be one or more types, and examples thereof include alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; aluminum; Included are metal compounds such as zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphorous acid compounds; phosphoric acid compounds; and amine compounds.

Specifically, examples of tin compounds include dibutyltin oxide, tin octylate, tin dioctylate, and salts thereof. Examples of titanium compounds include titanium alkoxides such as tetra-n-butyl titanate, tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; and titanium tetraacetylacetonate, titanium lactate, Includes titanium chelates such as titanium triethanolaminate. Examples of germanium compounds include germanium dioxide, and examples of aluminum compounds include oxides such as polyaluminum hydroxide, aluminum alkoxides, and tributyl aluminate.

The polymerization temperature of the crystalline polyester resin is preferably within the range of 150 to 250°C. Further, the polymerization time is preferably 0.5 to 10 hours. During the polymerization, the pressure inside the reaction system may be reduced if necessary.

The number of crystalline resins according to the present invention may be one, or two or more.

<Amorphous resin>
The amorphous resin according to the present invention is a resin that does not have the above-mentioned crystallinity. For example, the amorphous resin is a resin that does not have a melting point and has a relatively high glass transition temperature (Tg) when performing differential scanning calorimetry (DSC) of the amorphous resin or toner particles.

The Tg of the amorphous resin is preferably within the range of 20 to 80°C, particularly preferably within the range of 30 to 65°C.

The glass transition temperature can be measured according to the method (DSC method) specified in ASTM (American Society for Testing and Materials Standards) D3418-82. For the measurement, a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer), a TAC7/DX thermal analyzer controller (manufactured by PerkinElmer), or the like can be used. Specifically, 3.0 mg of toner is sealed in an aluminum pan and the measurement is performed. Use an empty aluminum pan as a reference. The first heating process is to raise the temperature from 0°C to 200°C at a raising/lowering rate of 10°C/min and hold it at 200°C for 1 minute, and then cool it from 200°C to 0°C at a cooling rate of 10°C/min for 1 minute. Under measurement conditions (heating/cooling conditions) in which the temperature is maintained isothermally at 0°C, and the second temperature raising process is performed from 0°C to 200°C at a rising/lowering rate of 10°C/min in this order. The glass transition temperature can be determined from the DSC curve obtained by the second heating process of raising the temperature to 200°C.

The number of amorphous resins may be one or more. Examples of amorphous resins include vinyl resins, urethane resins, urea resins, and amorphous polyester resins.

In the present invention, the amorphous resin preferably contains a vinyl resin as a main component in the binder resin, from the viewpoint of easy control of thermoplasticity, and preferably also contains an amorphous polyester resin. In the present invention, the term "main component" means that the binder resin contains 50% by mass or more of the resin.

The vinyl resin is, for example, a polymer of a vinyl compound, and examples thereof include acrylic ester resin, styrene-acrylic ester resin, and ethylene-vinyl acetate resin. Among these, styrene/acrylic acid ester resin (styrene/acrylic resin) is preferred from the viewpoint of plasticity during heat fixing.

Styrene/acrylic resin is formed by addition polymerizing at least a styrene monomer and a (meth)acrylic acid ester monomer. Styrene monomers include styrene represented by the structural formula of CH ₂ ═CH—C ₆ H ₅ as well as styrene derivatives having known side chains and functional groups in the styrene structure.

In addition, the (meth)acrylic acid ester monomer is represented by CH(R ₁ )=CHCOOR ₂ (R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group having 1 to 24 carbon atoms). In addition to acrylic esters and methacrylic esters, these esters also include acrylic ester derivatives and methacrylic ester derivatives having known side chains or functional groups in their structures.

Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p- Included are tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene and pn-dodecylstyrene.

Examples of (meth)acrylic acid ester monomers include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate (2EHA), stearyl Acrylic acid ester monomers such as acrylate, lauryl acrylate and phenyl acrylate; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-
Methacrylic acid esters such as butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate;

In addition, in this specification, "(meth)acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer", and one or both of them are means. For example, "methyl (meth)acrylate" means one or both of "methyl acrylate" and "methyl methacrylate."

The above-mentioned (meth)acrylic acid ester monomer may be one type or more than one type. For example, forming a copolymer using a styrene monomer and two or more types of acrylic acid ester monomers, or forming a copolymer using a styrene monomer and two or more types of methacrylic acid ester monomers. It is possible to form a copolymer, or to form a copolymer by using a styrene monomer, an acrylic acid ester monomer, and a methacrylic acid ester monomer together.

From the viewpoint of controlling the plasticity of the styrene/acrylic resin, the content of structural units derived from styrene monomer in the styrene/acrylic resin is preferably within the range of 40 to 90% by mass. Further, the content of the structural unit derived from the (meth)acrylic acid ester monomer in the amorphous resin is preferably within the range of 10 to 60% by mass.

The styrene/acrylic resin may further contain a structural unit derived from a monomer other than the styrene monomer and (meth)acrylic acid ester monomer. The other monomer is preferably a compound having a carboxy group or a hydroxy group.

The amorphous resin may further contain a structural unit derived from a monomer other than the styrene monomer and (meth)acrylic acid ester monomer. The other monomer is preferably a compound that forms an ester bond with a hydroxy group (-OH) derived from a polyhydric alcohol or a carboxy group (-COOH) derived from a polyhydric carboxylic acid. That is, the amorphous resin can be addition-polymerized with the above-mentioned styrene monomer and (meth)acrylic acid ester monomer, and a compound having a carboxyl group or a hydroxyl group (ampholyte compound) can be further polymerized. Preferably, it is a polymer consisting of:

Examples of the above compounds include compounds having a carboxy group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, etc.; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, Compounds having a hydroxyl group such as polyethylene glycol mono(meth)acrylate; are included.

The content of the structural unit derived from the amphoteric compound in the styrene-acrylic resin is preferably within the range of 0.5 to 20% by mass from the viewpoint of controlling the amount of toner charge.

The above-mentioned styrene-acrylic resin can be synthesized by a method of polymerizing monomers using a known oil-soluble or water-soluble polymerization initiator. Examples of oil-soluble polymerization initiators include azo or diazo polymerization initiators, and peroxide polymerization initiators.

Examples of the azo or diazo polymerization initiators include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis( cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile.

Examples of peroxide polymerization initiators include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxy carbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, , 4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane and tris-(t-butylperoxy)triazine.

Further, when synthesizing resin particles of styrene/acrylic resin by an emulsion polymerization method, a water-soluble radical polymerization initiator can be used as a polymerization initiator. Examples of water-soluble polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate, azobisminodipropane acetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

The weight average molecular weight (Mw) of the styrene-acrylic resin is preferably within the range of 5,000 to 150,000, more preferably within the range of 10,000 to 70,000, from the viewpoint of easy control of the plasticity of the amorphous resin. preferable.

(Amorphous polyester resin)
The amorphous polyester resin is a polyester resin that does not have a melting point and has a relatively high glass transition temperature (Tg) when differential scanning calorimetry (DSC) is performed. In addition, since the monomers constituting the amorphous polyester resin are different from the monomers constituting the crystalline polyester resin, they can be distinguished from the crystalline polyester resin by, for example, analysis such as NMR.

The amorphous polyester resin is obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid) and a divalent or higher alcohol (polyhydric alcohol). There is no particular restriction on the specific amorphous polyester resin, and any amorphous polyester resin conventionally known in the technical field may be used.

The specific method for producing the amorphous polyester resin is not particularly limited, and the amorphous polyester resin is produced by polycondensing (esterifying) a polyhydric carboxylic acid and a polyhydric alcohol using a known esterification catalyst. Resin can be manufactured.

The catalyst that can be used during production, the temperature of polycondensation (esterification), and the time of polycondensation (esterification) are not particularly limited, and are the same as those for the above-mentioned crystalline polyester resin.

The weight average molecular weight (Mw) of the amorphous polyester resin is not particularly limited, but is preferably within the range of 5,000 to 100,000, more preferably within the range of 5,000 to 50,000. When the weight average molecular weight (Mw) is 5,000 or more, the heat-resistant storage properties of the toner can be improved, and when it is 100,000 or less, the low-temperature fixability can be further improved. The weight average molecular weight (Mw) can be measured by the method described above.

Examples of polyhydric carboxylic acids and polyhydric alcohols used for preparing the amorphous polyester resin include, but are not particularly limited to, the following.

《Polyhydric carboxylic acid》
As the polycarboxylic acid, it is preferable to use unsaturated aliphatic polycarboxylic acids, aromatic polycarboxylic acids, and derivatives thereof. A saturated aliphatic polycarboxylic acid may be used in combination as long as an amorphous resin can be formed.

Examples of the unsaturated aliphatic polycarboxylic acids include methylene succinic acid, fumaric acid, maleic acid, 3-hexenedioic acid, 3-octenedioic acid, and alkenyl groups substituted with an alkenyl group having 2 to 20 carbon atoms. Unsaturated aliphatic dicarboxylic acids such as succinic acid; Unsaturated aliphatic tricarboxylic acids such as 3-butene-1,2,3-tricarboxylic acid, 4-pentene-1,2,4-tricarboxylic acid, aconitic acid; 4- Examples include unsaturated aliphatic tetracarboxylic acids such as pentene-1,2,3,4-tetracarboxylic acid. Furthermore, lower alkyl esters and acid anhydrides of these can also be used.

Examples of the aromatic polycarboxylic acids include phthalic acid, terephthalic acid, isophthalic acid, t-butyl isophthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-phenylene diacetic acid, and 2,6-naphthalene dicarboxylic acid. Aromatic dicarboxylic acids such as 4,4'-biphenyldicarboxylic acid and anthracenedicarboxylic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid (trimesic acid), Aromatic tricarboxylic acids such as 1,2,4-naphthalenetricarboxylic acid and hemimellitic acid; Aromatic tetracarboxylic acids such as pyromellitic acid and 1,2,3,4-butanetetracarboxylic acid; Aromatics such as mellitic acid Examples include hexacarboxylic acid. Furthermore, lower alkyl esters and acid anhydrides of these can also be used.

The above polycarboxylic acids may be used alone or in combination of two or more.

《Polyhydric alcohol》
As the polyhydric alcohol, from the viewpoint of controlling compatibility with the crystalline polyester resin, it is preferable to use unsaturated aliphatic polyhydric alcohols, aromatic polyhydric alcohols, and derivatives thereof. If an amorphous resin can be obtained, a saturated aliphatic polyhydric alcohol may be used in combination.

Examples of the unsaturated aliphatic polyhydric alcohol include 2-butene-1,4-diol, 3-butene-1,4-diol, 2-butyne-1,4-diol, and 3-butyne-1,4-diol. -diol, unsaturated aliphatic diols such as 9-octadecene-7,12-diol, and the like. Moreover, these derivatives can also be used.

Examples of the aromatic polyhydric alcohol include bisphenols such as bisphenol A and bisphenol F, alkylene oxide adducts of bisphenols such as ethylene oxide adducts and propylene oxide adducts thereof, and 1,3,5-benzenetriol. , 1,2,4-benzenetriol, 1,3,5-trihydroxymethylbenzene and the like. Moreover, these derivatives can also be used. Among these, it is preferable to use bisphenol A compounds such as ethylene oxide adducts and propylene oxide adducts of bisphenol A from the viewpoint that the thermal properties can be easily optimized.

Further, the number of carbon atoms in the polyhydric alcohol having a valence of 3 or more is not particularly limited, but it is preferably within the range of 3 to 20 carbon atoms because it is easy to optimize the thermal properties.

The above polyhydric alcohols may be used alone or in combination of two or more.

The amorphous polyester resin may be a hybrid amorphous polyester resin in which an amorphous polyester polymerized segment and a vinyl polymerized segment having a styrene-derived structural unit are chemically bonded.

The constituent components and content ratio of each segment in the hybrid amorphous polyester resin can be determined by, for example, NMR measurement or methylation reaction Py-GC/MS measurement.

The amorphous polyester polymerization segment is a portion derived from a known polyester resin obtained by a polycondensation reaction with a polyhydric carboxylic acid component and a polyhydric alcohol component similar to an amorphous polyester resin, and is a portion derived from a known polyester resin obtained by a polycondensation reaction with a polyhydric carboxylic acid component and a polyhydric alcohol component similar to an amorphous polyester resin, and is Refers to a polymerized segment in which no clear endothermic peak is observed in calorimetry (DSC).

Examples of the polyhydric carboxylic acid component include oxalic acid, succinic acid, maleic acid, adipic acid, 6-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, and dodecanedicarboxylic acid. , fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucinic acid, phthalic acid , isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylene diacetic acid, m-phenylene diglycolic acid, p-phenylene diglycolic acid, o-phenylene diglycolic acid , diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid, dodecenylsuccinic acid, and other dicarboxylic acids. Acids: trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, pyrenetetracarboxylic acid, and the like. These polyhydric carboxylic acids can be used alone or in combination of two or more. Among these, it is preferable to use aliphatic unsaturated dicarboxylic acids such as fumaric acid, maleic acid, and mesaconic acid, aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid, succinic acid, and trimellitic acid.

Examples of polyhydric alcohol components include ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct. dihydric alcohols such as; trihydric or higher polyols such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine; These polyhydric alcohol components can be used alone or in combination of two or more. Among these, dihydric alcohols such as bisphenol A ethylene oxide adduct and bisphenol A propylene oxide adduct are preferred.

The vinyl polymerization segment is not particularly limited as long as it contains a structural unit derived from styrene, but in consideration of plasticity during heat fixing, a styrene-(meth)acrylic acid ester polymerization segment (styrene/acrylic polymerization segment) is preferable. .

The styrene/acrylic polymerization segment is formed by addition polymerizing at least a styrene monomer and a (meth)acrylic acid ester monomer. Specific examples of monomers capable of forming a styrene/acrylic polymerized segment include those similar to the monomers described for the above styrene/acrylic resin, so their explanation will be omitted here.

The content of the styrene-derived structural unit in the vinyl polymerized segment is preferably in the range of 40 to 95% by mass based on the total amount of the vinyl polymerized segment. Further, the content of the structural unit derived from the (meth)acrylic acid ester monomer in the vinyl polymerized segment is preferably within the range of 5 to 60% by mass based on the total amount of the vinyl polymerized segment.

Furthermore, the vinyl polymerized segment is preferably addition-polymerized with a compound for chemically bonding to the amorphous polyester polymerized segment, in addition to the styrene monomer and (meth)acrylic acid ester monomer. Specifically, it is preferable to use a compound that forms an ester bond with the hydroxy group [-OH] derived from the polyhydric alcohol component or the carboxy group [-COOH] derived from the polyhydric carboxylic acid component contained in the crystalline polyester polymerization segment. . Therefore, the vinyl polymerized segment is capable of addition polymerization to styrene and (meth)acrylic acid ester monomers, and is obtained by further polymerizing a compound having a carboxy group [-COOH] or a hydroxy group [-OH]. That's preferable.

Examples of such compounds include compounds having a carboxy group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, and itaconic acid monoalkyl ester; 2-hydroxy Ethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate Examples include compounds having a hydroxy group, such as polyethylene glycol mono(meth)acrylate.

The content of the structural unit derived from the above compound in the vinyl polymerization segment is preferably within the range of 0.5 to 20% by mass based on the total amount of the vinyl polymerization segment.

The method for forming the styrene/acrylic polymerization segment is not particularly limited, and examples thereof include a method of polymerizing monomers using a known oil-soluble or water-soluble polymerization initiator. Specific examples of the polymerization initiator are the same as those explained in the section of the hybrid crystalline polyester resin above.

The content of the vinyl polymerized segment is preferably within the range of 2 to 25% by mass in the hybrid amorphous polyester resin.

Existing general schemes can be used as a method for producing the hybrid amorphous polyester resin. There are three typical methods:

(1) A method of producing a hybrid amorphous polyester resin by polymerizing a vinyl polymerized segment in advance and performing a polymerization reaction to form an amorphous polyester polymerized segment in the presence of the vinyl polymerized segment.

(2) A method of producing a hybrid amorphous polyester resin by forming an amorphous polyester polymerized segment and a vinyl polymerized segment, respectively, and then bonding them together.

(3) A method of manufacturing a hybrid amorphous polyester resin by polymerizing an amorphous polyester polymerized segment in advance and performing a polymerization reaction to form a vinyl polymerized segment in the presence of the amorphous polyester polymerized segment.

3.3. Colorant The colorant according to the present invention may be one or more types. Examples of typical colorants include colorants for magenta, yellow, cyan, and black.

Examples of colorants for magenta include C. I. Pigment Red 2, 3, 5, 6, 7, 15, 16, 48:1, 53:1, 57:1, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 139, 144, 149, 150, 163, 166, 170, Includes 177, 178, 184, 185, 188, 202, 206, 207, 209, 222, 238, and 269.

Examples of colorants for yellow include C. I. Pigment Orange 31, 38, 43, C. I. Pigment Yellow 12, 14, 15, 17, 74, 83, 93, 94, 138, 155, 162, 180 and 185 are included.

Examples of colorants for cyan include C.I. I. Pigment Blue 2, 3, 15, 15:2, 15:3, 15:4, 16, 17, 60, 62, 66 and C. I. Contains Pigment Green 7.

Examples of colorants for black include carbon black and magnetic particles. Examples of carbon blacks include channel black, furnace black, acetylene black, thermal black and lamp black. Examples of magnetic particles include ferromagnetic metals such as iron, nickel, and cobalt; alloys containing these metals; compounds of ferromagnetic metals such as ferrite and magnetite; chromium dioxide; and ferromagnetic metals. Alloys that exhibit ferromagnetism by heat treatment are included. Examples of alloys that exhibit ferromagnetism upon heat treatment include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin.

The content of the colorant in the toner base particles can be determined appropriately and independently, and for example, from the viewpoint of ensuring color reproducibility of images, it is preferably within the range of 1 to 30% by mass. It is preferably in the range of 2 to 20% by mass.

Furthermore, the size of the particles of the colorant is preferably within the range of 10 to 1000 nm, for example, preferably within the range of 50 to 500 nm, and more preferably within the range of 80 to 300 nm, in terms of volume average particle size. It is even more preferable that there be.

The volume average particle size may be a catalog value, and for example, the volume average particle size (median diameter on a volume basis) of the colorant may be measured using "UPA-150" (manufactured by Microtrac Bell Co., Ltd.). can do.

3.4. Other materials <Release agent>
As the mold release agent used in the present invention, any known release agent can be used.

The mold release agent may be one or more types. Examples of mold release agents include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax; long chain hydrocarbon waxes such as paraffin wax and Sasol wax; and distearyl. Dialkyl ketone wax such as ketone, carnauba wax, montan wax, behenyl behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1, Included are ester waxes such as 18-octadecanediol distearate, tristearyl trimellitate, and distearyl maleate, and amide waxes such as ethylenediamine behenylamide and tristearyl trimellitate.

The above-mentioned mold release agent is easily compatible with the vinyl resin. Therefore, due to the plasticizing effect of the release agent, the sharp melting properties of the toner can be enhanced and sufficient low-temperature fixability can be obtained. The above-mentioned release agent is preferably an ester wax (ester compound) from the viewpoint of obtaining sufficient low-temperature fixing properties, and a linear ester-based wax from the viewpoint of achieving both heat resistance and low-temperature fixing properties. (linear ester compound) is more preferable.

The melting point of the mold release agent is preferably 60°C or higher, more preferably 65°C or higher, from the viewpoint of obtaining sufficient high-temperature storage stability. Further, the melting point of the release agent is preferably 100° C. or lower, and more preferably 90° C. or lower, from the viewpoint of obtaining sufficient low-temperature fixability of the toner.

Further, the content of the release agent in the toner of the present invention is preferably within the range of 1 to 30% by mass, and more preferably within the range of 5 to 20% by mass.

The toner of the present invention may further contain components other than the above-mentioned crystalline resin, amorphous resin, and release agent, as long as the effects according to the present embodiment are achieved. For example, examples of the other components that the toner base particles may contain include a colorant and a charge control agent.

<Charge control agent>
Known charge control agents can be used for the present invention, examples include nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes and salicylic acid metal salts.

The content of the charge control agent in the toner of the present invention is generally in the range of 0.1 to 10 parts by weight, preferably in the range of 0.5 to 5% by weight, based on 100 parts by weight of the binder resin.

Further, the particle size of the charge control agent is, for example, within the range of 10 to 1000 nm in number average primary particle size, preferably within the range of 50 to 500 nm, and more preferably within the range of 80 to 300 nm. .

3.5. Method for producing toner particles The method for producing toner particles according to the present invention is not particularly limited, and may be any known method such as kneading and pulverization method, suspension polymerization method, emulsion aggregation method, dissolution suspension method, polyester elongation method, dispersion polymerization method, etc. There are several methods.
Among these, the emulsion aggregation method is preferred from the viewpoint of particle size uniformity and shape controllability. In the emulsion aggregation method, a dispersion of binder resin particles dispersed by a surfactant or dispersion stabilizer is mixed with a dispersion of colorant particles, if necessary, to obtain the desired toner particle size. In this method, toner base particles are produced by agglomerating the toner base particles until the particles are agglomerated, and then controlling the shape by fusing the particles of the binder resin. Here, the binder resin particles may optionally contain a release agent, a charge control agent, and the like.

<Average circularity of toner base particles>
From the viewpoint of improving low-temperature fixability, the average circularity of the toner base particles is preferably within the range of 0.920 to 1.000, more preferably within the range of 0.925 to 0.975. .

Here, the average circularity is a value measured using "FPIA-3000" (manufactured by Malvern Panalytical). Specifically, toner base particles are wetted with a surfactant aqueous solution, ultrasonic dispersion is performed for 1 minute, and after dispersion, using "FPIA-3000", measurement conditions are HPF (high magnification imaging) mode. Measurement is performed at an appropriate concentration for 4000 detections. Circularity is calculated using the following formula.

Circularity = (perimeter of a circle with the same projected area as the particle image) / (perimeter of the particle projection image)
The average circularity is an arithmetic mean value obtained by adding up the circularity of each particle and dividing the sum by the total number of particles measured.

<Particle size of toner base particles>
Regarding the particle size of the toner base particles, it is preferable that the volume-based median diameter (D50) is 3 to 10 μm. By setting the volume-based median diameter within the above range, it is possible to achieve fine line reproducibility and high image quality of photographic images, and toner consumption is reduced compared to when using large particle size toner. be able to. Further, toner fluidity can also be ensured.

Here, the volume-based median diameter (D50) of the toner base particles is measured and calculated using, for example, a device that is connected to a "Coulter Multisizer 3" (manufactured by Beckman Coulter) and a computer system for data processing. can do.

The volume-based median diameter of the toner base particles can be controlled by the concentration of the flocculant, the amount of solvent added, or the fusion time in the aggregation/fusion process during toner production, which will be described later, as well as the composition of the resin component. I can do it.

<External additive addition process>
This step is a step performed when an external additive is added to the toner base particles.

As a mixing device for the external additive, a mechanical mixing device such as a Henschel mixer, a coffee mill, a sample mill, etc. can be used. The circumferential speed of the rotor when adding the external additive is preferably 30 to 35 mm/sec.

Further, the mixing time for the external additive is preferably 12 to 15 minutes, and the temperature when adding the external additive is preferably 25 to 35 degrees.

3.6. Developer The toner according to the present invention can be used as a magnetic or non-magnetic one-component developer, or may be mixed with a carrier and used as a two-component developer. When the toner is used as a two-component developer, magnetic particles made of conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead are used as carriers. ferrite particles are particularly preferred. Further, as the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a dispersed carrier in which magnetic fine powder is dispersed in a binder resin, etc. may be used.

The volume average particle diameter of the carrier is preferably within the range of 20 to 100 μm, more preferably within the range of 25 to 80 μm. The volume average particle diameter of the carrier can be typically measured using a laser diffraction particle size distribution measuring device "HELOS" (manufactured by Sympatik) equipped with a wet dispersion machine.

The two-component developer can be produced by mixing the carrier and toner described above using a mixing device. Examples of the mixing device include Henschel mixer, Nauta mixer, V-type mixer, and the like.

The amount of toner to be blended when producing a two-component developer is preferably within the range of 1 to 10% by weight based on 100% by weight of the total of carrier and toner.

4. Image Forming System The image forming system of the present invention uses the electrostatic image developing toner and electrophotographic photoreceptor according to the present invention, and has at least a charging step, an exposure step, a developing step, and a transfer step. It is. That is, the present invention is a system for forming an image using the toner for developing an electrostatic image according to the present invention in an image forming apparatus that is equipped with the electrophotographic photoreceptor according to the present invention and is capable of performing the steps described above.

4.1. Electrophotographic image forming method The image forming method of the present invention is an image forming method having at least a latent image forming step, a developing step, an intermediate transfer step, and a transfer step, and comprises the above-mentioned toner for developing an electrostatic image according to the present invention; It is characterized by using an electrophotographic photoreceptor. Note that a more specific method will be described in the description of the image forming apparatus below.

<Recording medium>
The recording medium (also referred to as recording material, recording paper, recording paper, etc.) used in the image forming method of the present invention may be one that is generally used. There is no particular limitation as long as it holds a toner image. Usable image supports include, for example, plain paper from thin paper to thick paper, high-quality paper, art paper, coated printing paper such as coated paper, commercially available Japanese paper, postcard paper, OHP paper, etc. Examples include plastic films, cloth, various resin materials used in so-called flexible packaging, resin films formed from these materials, and labels.

4.2. Image Forming Apparatus The image forming method of the present invention can be carried out in a conventionally known electrophotographic image forming apparatus by using the electrostatic image developing toner and the electrophotographic photoreceptor according to the present invention.

The image forming apparatus includes a photoreceptor, a means for forming an electrostatic latent image on the photoreceptor, a means for developing the electrostatic latent image with toner to form a toner image, and a means for transferring the formed toner image onto paper. and means for fixing the transferred toner image on the paper.

FIG. 2 is a schematic configuration diagram showing an example of the configuration of an image forming apparatus used in the image forming method of the present invention.

The image forming apparatus 100 shown in FIG. 2 includes image forming units 10Y, 10M, 10C, and 10Bk that form yellow, magenta, cyan, or black toner images, respectively, and image forming units 10Y, 10M, 10C, and 10Bk that form yellow, magenta, cyan, or black toner images, respectively. The image forming apparatus main body 100A includes an intermediate transfer unit 7 that transfers toner images of each color onto the paper P, and a fixing unit 24 that fixes the toner images to the paper P. Further, a document image reading device SC for optically scanning a document and reading image information as digital data (document image data) is arranged at the top of the image forming apparatus main body 100A.

Image forming units 10M, 10C, and 10Bk each form toner images using magenta toner, cyan toner, and black toner instead of yellow toner, and basically have the same configuration as image forming unit 10Y. It is something. Therefore, the image forming unit 10Y will be explained below as an example, and the explanation of the image forming units 10M, 10C, and 10Bk will be omitted.

The image forming unit 10Y includes a charging unit 2Y that applies a uniform potential to the surface of the photoreceptor 1Y around the drum-shaped photoreceptor 1Y, which is an image forming body, and a charging unit 2Y that exposes the uniformly charged photoreceptor 1Y. The exposure means 3Y performs exposure based on the image data signal (yellow) to form an electrostatic latent image corresponding to a yellow image, and conveys toner onto the photoreceptor 1Y to visualize the electrostatic latent image. A developing means 4Y and a cleaning means 6Y for collecting residual toner remaining on the photoreceptor 1Y after the primary transfer are arranged to form a yellow (Y) toner image on the photoreceptor 1Y.

As the charging means 2Y, a corona discharge type charger is used.

The exposure means 3Y is a light irradiation device that uses a light emitting diode as an exposure light source and includes, for example, an LED section in which light emitting elements made of light emitting diodes are arranged in an array in the axial direction of the photoreceptor 1Y, and an imaging element. It also consists of a laser irradiation device with a laser optical system that uses a semiconductor laser as an exposure light source. The image forming apparatus 100 shown in FIG. 1 is provided with a laser irradiation device.

The exposure means 3Y is preferably a device using a semiconductor laser or a light emitting diode with an oscillation wavelength of 350 to 850 nm as an exposure light source. By using such an exposure light source with the exposure dot diameter in the main scan direction of writing narrowed down to 10 to 100 μm and performing digital exposure on the photoreceptor 1Y, high resolution electrophotographic images of 600 to 2400 dpi or higher can be created. can be obtained.

The exposure method in the exposure means 3Y may be a scanning optical system using a semiconductor laser, or a solid-state type using an LED.

The intermediate transfer unit 7 is formed by an endless belt-shaped intermediate transfer body 70 stretched by a plurality of support rollers 71 to 74 and supported so as to be able to circulate, and image forming units 10Y, 10M, 10C, and 10Bk, respectively. Primary transfer rollers 5Y, 5M, 5C, and 5Bk are used to transfer the toner image onto the intermediate transfer body 70, and the toner image transferred onto the intermediate transfer body 70 by the primary transfer rollers 5Y, 5M, 5C, and 5Bk is transferred onto the paper P. The intermediate transfer member 70 has a secondary transfer roller 5b for transferring toner, and a cleaning means 6b for collecting residual toner remaining on the intermediate transfer member 70.

The primary transfer roller 5Bk in the intermediate transfer unit 7 is always in contact with the photoreceptor 1Bk during the image forming process, and the other primary transfer rollers 5Y, 5M, and 5C are in contact with each other only when forming a color image. It is brought into contact with the corresponding photoreceptors 1Y, 1M, and 1C.

Further, the secondary transfer roller 5b is brought into contact with the intermediate transfer body 70 only when the paper P passes therethrough and secondary transfer is performed.

The fixing means 24 includes, for example, a heating roller 241 equipped with a heating source inside, a pressure roller 242 that is provided in pressure contact with the heating roller 241 so as to form a fixing nip portion, and the like. There is.

In the image forming apparatus 100 as described above, the surfaces of the photoreceptors 1Y, 1M, 1C, and 1Bk are charged by the charging means 2Y, 2M, 2C, and 2Bk. The exposure means 3Y, 3M, 3C, and 3Bk are operated in accordance with exposure image data signals for each color obtained by performing various image processing and the like on the original image data obtained by the original image reading device SC. Specifically, a laser beam modulated in accordance with the image data signal for exposure is output from an exposure light source, and the photoreceptors 1Y, 1M, 1C, and 1Bk are scanned and exposed by this laser beam. As a result, electrostatic latent images corresponding to the colors of yellow, magenta, cyan, and black corresponding to the original read by the original image reading device SC are formed on each of the photoreceptors 1Y, 1M, 1C, and 1Bk, respectively.

Next, the electrostatic latent images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are developed with toner of each color by developing means 4Y, 4M, 4C, and 4Bk, thereby forming toner images of each color. Then, the toner images of each color are sequentially transferred onto the intermediate transfer member 70 by the primary transfer rollers 5Y, 5M, 5C, and 5Bk, and are superimposed and combined to form a color toner image.

Furthermore, in synchronization with the formation of the color toner image, the paper P housed in the paper feed cassette 20 is fed by the paper feed means 21, and passes through the plurality of intermediate rollers 22A, 22B, 22C, 22D and registration rollers 23. After that, it is conveyed to the secondary transfer roller 5b. Then, the color toner images transferred onto the intermediate transfer body 70 by the secondary transfer roller 5b are transferred onto the paper P at once.

The color toner image transferred onto the paper P is fixed by applying heat and pressure by the fixing means 24, thereby forming a visible image (toner layer). Thereafter, the paper P on which the visible image has been formed is ejected out of the machine from the ejection port 26 by the ejection roller 25 and placed on the ejection tray 27 .

In addition, when performing double-sided printing, the paper P on which an image is formed on the first side, which is transported from the fixing means 24, is transported from the switching gate 31 into the reversing transport path 32, and after the paper P is turned over, The paper is re-fed near the intermediate roller 22D, and an image is formed on the second side of the paper P.

After the toner images of each color were transferred to the intermediate transfer member 70, the photoreceptors 1Y, 1M, 1C, and 1Bk remained on the photoreceptors 1Y, 1M, 1C, and 1Bk by the cleaning means 6Y, 6M, 6C, and 6Bk, respectively. After the toner is removed, the next toner image of each color is formed.

On the other hand, after the color toner image is transferred onto the paper P by the secondary transfer roller 5b and the paper P is separated by curvature, the toner remaining on the intermediate transfer body 70 is removed by the cleaning means 6b. After that, it is used for intermediate transfer of the next toner image.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various changes can be made.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. In the examples, "parts" or "%" are used, but unless otherwise specified, "parts by mass" or "% by mass" are expressed.

[Preparation of photoreceptor 1]
A. Preparation of conductive support A conductive support was prepared by cutting the surface of a cylindrical aluminum support.

B. Preparation of Undercoat Layer The following components were mixed in the following amounts and dispersed in a batch mode for 10 hours using a sand mill as a dispersion machine to prepare a coating solution for the undercoat layer.

The coating solution was applied onto the surface of the conductive support by dip coating and dried at 110° C. for 20 minutes to form a subbing layer with a thickness of 2 μm on the conductive support.

Note that X1010 (Daicel Degussa Corporation) was used as the polyamide resin.
Moreover, SMT500SAS (Tayka Corporation) was used as titanium oxide particles.

Polyamide resin 10 parts by mass Titanium oxide particles 11 parts by mass Ethanol 200 parts by mass

C. Preparation of charge generation layer The following components are mixed in the following amounts and dispersed for 0.5 hours using a circulating ultrasonic homogenizer (RUS-600TCVP; Nippon Seiki Seisakusho Co., Ltd.) at 19.5 kHz and 600 W at a circulating flow rate of 40 L/hour. In this way, a coating solution for a charge generation layer was prepared.

The coating solution was applied to the surface of the undercoat layer by dip coating and dried to form a charge generation layer with a layer thickness of 0.3 μm on the undercoat layer.

The charge-generating substances include titanyl phthalocyanine and (2R, 3R), which have clear peaks at 8.3°, 24.7°, 25.1°, and 26.5° in the Cu-Kα characteristic X-ray diffraction spectrum measurement. A mixed crystal of a 1:1 adduct of -2,3-butanediol and unadducted titanyl phthalocyanine was used.

In addition, S-LEC BL-1 (Sekisui Chemical Co., Ltd., "S-LEC" is a registered trademark of the company) was used as a polyvinyl butyral resin. In addition, 3-methyl-2-butanone/cyclohexanone=4/1 (V/V) was used as a mixed liquid.

Charge generating substance 24 parts by mass Polyvinyl butyral resin 12 parts by mass Mixed liquid 400 parts by mass

D. Preparation of Charge Transport Layer A charge transport layer coating solution containing the following components mixed in the amounts shown below is applied to the surface of the charge generation layer by dip coating, and dried at 120°C for 70 minutes to form a charge transport layer with a layer thickness of 27 μm. A layer was formed on the charge transport layer.

Note that Z300 (Mitsubishi Gas Chemical Co., Ltd.) was used as the polycarbonate resin. In addition, IRGANOX 1010 (BASF, "IRGANOX" is a registered trademark of BASF) was used as an antioxidant.

Charge transport material represented by the following structural formula (1) 24 parts by mass Charge transport material represented by the following structural formula (2) 36 parts by mass Polycarbonate resin 100 parts by mass Antioxidant 4 parts by mass

[Preparation of photoreceptors 2 and 3]
Photoreceptors 2 and 3 were prepared in the same manner as in the preparation of Photoreceptor 1 except that the charge transport substance added to the charge transport layer was changed as shown in Table I.

<Preparation of titanate compound particles>
(1) Preparation of strontium titanate particles 1 Metatitanic acid obtained by the sulfuric acid method is bleached to remove iron, and then an aqueous sodium hydroxide solution is added to adjust the pH to 9.0 (measurement temperature 25°C), followed by a desulfurization treatment. The mixture was neutralized to pH 5.8 (measurement temperature: 25°C) with hydrochloric acid, and filtered and washed with water.

Water was added to the washed cake to make a slurry of 1.85 mol/L of TiO ₂ , and then hydrochloric acid was added to adjust the pH to 1.0 to perform peptization treatment.

0.625 mol of this metatitanic acid as TiO ₂ was collected and charged into a 3 L reaction vessel. A strontium chloride aqueous solution and a lanthanum chloride aqueous solution were placed in the reaction vessel at a molar ratio of Sr ²⁺ :La ³⁺ :Ti ⁴⁺ of 1.00:0.18:1.00 (in Table II, SrO/LaO/TiO ₂ =1. (expressed as 00/0.18/1.00)
, a total of 0.719 mol was added, and the TiO ₂ concentration was adjusted to 0.313 mol/L.

Next, after heating to 90°C while stirring and mixing, 296 mL of a 5N aqueous sodium hydroxide solution was added over 10 hours, and then stirring was continued at 95°C for 1 hour to complete the reaction.

The reaction slurry was cooled to 50°C, hydrochloric acid was added until the pH reached 5.0 (measurement temperature: 25°C), and stirring was continued for 1 hour.
The obtained precipitate was washed by decantation, and the slurry containing the precipitate was adjusted to pH 6.5 (measurement temperature 25°C) by adding hydrochloric acid, and 9% by mass of isobutyltrimethoxysilane was added to the solid content to give 1. Stirring was continued for an hour.

Next, filtration and washing were performed, and the resulting cake was dried in the atmosphere at 120° C. for 8 hours to obtain lanthanum-containing strontium titanate particles (1).

The number average particle diameter of the primary particles calculated using an electron microscope was 30 nm. Further, the circularity was 0.85.

(2) Production of strontium titanate particles 2 to 6 In the method for producing strontium titanate particles 1, the molar ratio [Sr ₂ +:La ₃ +:Ti ₄ +] when adding the strontium chloride aqueous solution and the lanthanum chloride aqueous solution , the addition time of 296 mL of 5N sodium hydroxide aqueous solution was changed as shown in Table II, and strontium titanate particles 2 to 6 were produced.

(3) Preparation of calcium titanate particles Strontium titanate particles 1 were prepared in the same manner as in the preparation of strontium titanate fine particles 1, except that an aqueous calcium chloride solution was used instead of an aqueous strontium chloride solution. Obtained.

When the obtained fine particles were observed with an electron microscope, the number average particle diameter of the primary particles was 32 nm. Further, the circularity was 0.85.

(4) Preparation of barium titanate particles In the preparation of strontium titanate particles 1, barium titanate particles 1 were prepared in the same manner as in the preparation of strontium titanate fine particles 1, except that a barium chloride aqueous solution was used instead of a strontium chloride aqueous solution. Obtained.

When the obtained fine particles were observed with an electron microscope, the number average particle diameter of the primary particles was 33 nm. Further, the circularity was 0.86.

<Preparation of spherical silica particles>
(1) Preparation of Silica Particles 1 945 parts by mass of ethanol and 405 parts by mass of tetraethoxytoxysilane were added to a 3-liter reactor equipped with a stirrer, a dropping funnel, and a thermometer, and the mixture was stirred and adjusted to 35°C.

Next, 135 parts by mass of an aqueous solution in which 82 parts by mass of 28% aqueous ammonia was dissolved was added over 29 minutes and mixed. Further, after the dropwise addition, stirring was continued for 1 hour to perform hydrolysis, thereby obtaining a suspension of silica particles.
4.8 parts by mass of methyltrimethoxysilane was added dropwise to this aqueous suspension at room temperature to hydrophobize the surfaces of the silica particles.

The thus obtained dispersion was heated to 80° C. and ethanol was distilled off.
130 parts by mass of hexamethyldisilazane was added to the obtained dispersion at room temperature, heated to 60° C., and reacted for 9 hours to trimethylsilylate the silica particles.
Thereafter, the solvent was distilled off under reduced pressure to produce silica particles 1.

When the number average primary particle size and coefficient of variation of the silica particles 1 obtained by the above method were measured, the number average primary particle size of the primary particles was 10 nm and the coefficient of variation was 18.1%.

(2) Production of Silica Particles 2 to 4 In the production of Silica Particles 1, Silica Particles 2 to 4 were produced by varying the amount and addition time of 28% ammonia water as shown in Table III. The number average particle diameters and coefficients of variation of silica particles 2 to 4 were as shown in Table IV.

[Preparation of toner particles 1]
<Preparation of styrene-acrylic (StAc) resin particle dispersion>
(1st stage polymerization)
4 parts by mass of an anionic surfactant made of sodium dodecyl sulfate (C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ SO ₃ Na) was ionized into a reaction vessel equipped with a stirring device, a temperature sensor, a cooling tube, and a nitrogen introducing device. An aqueous surfactant solution dissolved in 3040 parts by mass of exchanged water was added.

Furthermore, a polymerization initiator solution in which 10 parts by mass of potassium persulfate (KPS) was dissolved in 400 parts by mass of ion-exchanged water was added, and the temperature of the solution was raised to 75°C.

Next, a polymerizable monomer solution consisting of 532 parts by mass of styrene, 200 parts by mass of n-butyl acrylic acid, 68 parts by mass of methacrylic acid, and 16.4 parts by mass of n-octyl mercaptan was added dropwise over 1 hour.

After dropping, polymerization (first stage polymerization) was performed by heating and stirring at 75° C. for 2 hours to prepare a dispersion of styrene-acrylic resin particles.

The weight average molecular weight (Mw) of the styrene-acrylic resin particles in the dispersion was 16,500.

(Second stage polymerization)
In a flask equipped with a stirring device, polymerizable monomers consisting of 101.1 parts by mass of styrene, 62.2 parts by mass of n-butyl acrylic acid, 12.3 parts by mass of methacrylic acid, and 1.75 parts by mass of n-octyl mercaptan were placed. Added body fluid.

Further, 93.8 parts by mass of paraffin wax HNP-0190 (manufactured by Nippon Seiwa Co., Ltd.) was added as a mold release agent, and the mixture was heated to an internal temperature of 90° C. to dissolve it, thereby preparing a monomer solution.

A surfactant aqueous solution prepared by dissolving 3 parts by mass of the anionic surfactant used in the first stage polymerization in 1560 parts by mass of ion-exchanged water was placed in another container, and heated to an internal temperature of 98°C.

To this surfactant aqueous solution, 32.8 parts by mass (solid content equivalent) of a dispersion of styrene-acrylic resin particles obtained by the first stage polymerization was added, and a monomer solution containing paraffin wax was further added. .

A dispersion of emulsified particles (oil droplets) having a particle diameter of 340 nm was prepared by mixing and dispersing for 8 hours using a mechanical disperser Clairmix (manufactured by M Techniques) having a circulation path.

A polymerization initiator solution containing 6 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water was added to this dispersion. Polymerization (second stage polymerization) was performed by heating and stirring this system at 98° C. for 12 hours to prepare a dispersion of styrene-acrylic resin particles.

The weight average molecular weight (Mw) of the styrene-acrylic resin particles in the dispersion was 23,000.

(Third stage polymerization)
A polymerization initiator solution containing 5.45 parts by mass of potassium persulfate dissolved in 220 parts by mass of ion-exchanged water was added to the dispersion of styrene-acrylic resin particles obtained in the second stage polymerization.

To this dispersion, 1 part of a polymerizable monomer solution consisting of 293.8 parts by mass of styrene, 154.1 parts by mass of n-butyl acrylic acid, and 7.08 parts by mass of n-octyl mercaptan was added at a temperature of 80°C. It dripped over time.

After completion of the dropwise addition, polymerization (third stage polymerization) was carried out by heating and stirring for 2 hours, followed by cooling to 28° C. to obtain a dispersion of styrene-acrylic resin particles.

The weight average molecular weight (Mw) of the styrene-acrylic resin particles in the dispersion was 26,800.

<Preparation of amorphous polyester resin particle dispersion>
139.5 parts by mass of terephthalic acid and 15.5 parts by mass of isophthalic acid as polycarboxylic acid monomers were added to a reaction vessel equipped with a stirring device, a nitrogen inlet tube, a temperature sensor, and a rectification column. As polymers, 290.4 parts by mass of 2-mol adduct of 2,2-bis(4-hydroxyphenyl)propane propylene oxide (molecular weight 460) and 2-mol adduct of 2,2-bis(4-hydroxyphenyl)propane ethylene oxide. (Molecular weight: 404) 60.2 parts by mass was added.

The temperature of the reaction system was raised to 190° C. over 1 hour, and after confirming that the inside of the reaction system was uniformly stirred, 3.21 parts by mass of tin octylate was added as a catalyst.

While distilling off the water produced, the temperature of the reaction system was raised from the same temperature to 240°C over 6 hours, and the dehydration condensation reaction was continued for 6 hours while maintaining the temperature at 240°C. Resin was obtained.

The obtained amorphous polyester resin had a peak molecular weight (Mp) of 12,000 and a weight average molecular weight (Mw) of 15,000.
Methyl ethyl ketone and isopropyl alcohol were added to a reaction vessel equipped with an anchor blade to provide stirring power.

Furthermore, the amorphous polyester resin roughly pulverized with a hammer mill was gradually added and stirred to completely dissolve it to obtain a polyester resin solution that became an oil phase.

Several amounts of a dilute ammonia aqueous solution were dropped into the stirred oil phase, and then this oil phase was dropped into ion-exchanged water to effect phase inversion emulsification, and then the solvent was removed while reducing the pressure using an evaporator.

Amorphous polyester resin particles were dispersed in the reaction system, and ion-exchanged water was added to the dispersion to adjust the solid content to 20% by mass to prepare a dispersion of amorphous polyester resin particles. .

The volume-based median diameter of the amorphous polyester resin particles in the dispersion was measured using a particle size distribution analyzer "Nanotrack Wave" (manufactured by Microtrack Bell Co., Ltd.) and found to be 216 nm.

<Preparation of crystalline polyester resin particle dispersion>
In a reaction tank equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, 118 parts by mass of 1,6-hexanediol, 271 parts by mass of tetradecanedioic acid, and 0.8 parts by mass of titanium tetraisopropoxide as a polycondensation catalyst were added. The mixture was added in 10 portions and reacted at 235° C. for 5 hours under a nitrogen stream while distilling off the generated water.
Next, a reaction was carried out for 1 hour under reduced pressure of 13.3 kPa (100 mmHg) to synthesize a crystalline polyester resin.

100 parts by mass of the obtained crystalline polyester resin was pulverized with "Randell Mill format: RM" (manufactured by Tokuju Kosho Co., Ltd.), and mixed with 638 parts by mass of a sodium lauryl sulfate solution with a concentration of 0.26% by mass prepared in advance, While heating and stirring at 90°C, perform ultrasonic dispersion using an ultrasonic homogenizer "US-150T" (manufactured by Nippon Seiki Seisakusho) at V-LEVEL and 300 μA for 30 minutes, and add ion-exchanged water to the dispersion to reduce the solid content. was adjusted to 20% by mass to produce a crystalline polyester resin fine particle dispersion having a volume-based median diameter of 200 nm.

<Preparation of colorant particle dispersion>
While stirring a solution of 90 parts by mass of sodium dodecyl sulfate dissolved in 1,600 parts by mass of ion-exchanged water, C.I. I. 420 parts by mass of Pigment Blue 15:3 (manufactured by Toyo Ink Co., Ltd.) was gradually added.
Next, a colorant particle dispersion liquid was prepared by carrying out a dispersion treatment using a stirring device "Creamix (manufactured by M Techniques)".

<Preparation of toner base particles>
In a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube, add 270 parts by mass of the styrene acrylic resin particle dispersion in terms of solid content, 30 parts by mass of the crystalline polyester resin particle dispersion in terms of solid content, and 2000 parts of ion-exchanged water. After adding part by mass, a 5 mol/liter aqueous sodium hydroxide solution was added to adjust the pH to 10 (measurement temperature: 25° C.).

Thereafter, 40 parts by mass of a colorant dispersion liquid was added in terms of solid content.
Next, an aqueous solution of 60 parts by mass of magnesium chloride dissolved in 60 parts by mass of ion-exchanged water was added at 30° C. over 10 minutes with stirring.

Thereafter, after leaving the system for 3 minutes, the temperature was started to increase, and the temperature of this system was increased to 80°C over 60 minutes, and the particle growth reaction was continued while maintaining the temperature at 80°C.

In this state, the particle size of the aggregated particles was measured using "Multicizer 3" (manufactured by Beckman Coulter), and when the volume-based median diameter (D50) reached 4.9 μm, the amorphous polyester resin particles 30 parts by mass of the dispersion in terms of solid content was added over 30 minutes, and when the supernatant of the reaction liquid became transparent, an aqueous solution of 190 parts by mass of sodium chloride dissolved in 760 parts by mass of ion-exchanged water was added. to stop particle growth.

Furthermore, the temperature was raised and the particles were heated and stirred at 90°C to advance the fusion of the particles. When the average circularity reached 0.962, the particles were cooled to 30° C. to prepare a dispersion of toner base particles.

The toner base particle dispersion prepared through the above steps was subjected to solid-liquid separation using a basket type centrifugal separator "MARK III model number 60x40 (manufactured by Matsumoto Kikai Co., Ltd.)" to form a wet cake of toner base particles.

This wet cake was washed with ion-exchanged water at 45°C using the basket-type centrifuge described above until the electrical conductivity of the filtrate reached 5 μS/cm, and then using a "Flash Jet Dryer (manufactured by Seishin Enterprise Co., Ltd.)" Cyan toner base particles were produced by transferring the mixture to a drying process and drying it until the water content became 0.5% by mass.

<External additive treatment process>
The toner base particles produced as described above, strontium titanate 1, silica particles 1, and hydrophobic silica particles (HМDS treated, degree of hydrophobicity 72%, number average particle diameter of primary particles 20 nm) were mixed. , external addition treatment was performed.

Henschel mixer type " FM20C/I'' (manufactured by Nippon Coke Industry Co., Ltd.).

Next, the rotational speed was set so that the circumferential speed of the tip of the blade was 40 m/s, and the mixture was stirred for 15 minutes to carry out an external addition process, thereby producing Toner 1.

Furthermore, the temperature during the external addition treatment was set within the range of 39 to 41°C.

Specifically, when the temperature inside the Henschel mixer reaches 41°C, cooling water is flowed into the outer bath of the Henschel mixer at a flow rate of 5 L/min, and when the temperature reaches 39°C, the temperature inside the Henschel mixer reaches 41°C. The temperature inside the Henschel mixer was controlled by flowing cooling water into the outer bath of the Henschel mixer at a flow rate of 1 L/min.

[Preparation of toner particles 2 to 17]
In the production of toner particles 1, toner particles 2 to 17 were produced by changing the titanic acid compound particles and spherical silica particles as shown in Table V.

[Preparation of carrier]
<Preparation of core material particles 1>
The raw materials were weighed so that MnO: 35 mol%, MgO: 14.5 mol%, Fe ₂ O ₃ : 50 mol% and SrO: 0.5 mol% were mixed with water, and then ground in a wet media mill for 5 hours. Got slurry.

The obtained slurry was dried with a spray dryer to obtain perfectly spherical particles. After adjusting the particle size of the particles, they were heated at 950° C. for 2 hours and pre-calcined in a rotary kiln.

After grinding with a dry ball mill for 1 hour using stainless steel beads with a diameter of 0.3 cm, 0.8% by mass of PVA was added as a binder based on the solid content, water and a dispersant were further added, and a ball with a diameter of 0.5 cm was ground. It was ground for 25 hours using zirconia beads.

Next, the mixture was granulated and dried using a spray dryer, and main firing was performed in an electric furnace at a temperature of 1050° C. for 20 hours. Thereafter, it was crushed, further classified to adjust the particle size, and then low-magnetic products were separated by magnetic separation to obtain core material particles 1. The volume average particle diameter of core material particles 1 was 28.0 μm.

<Preparation of coating resin 1>
100 parts by mass of cyclohexyl methacrylate monomer and 1 part by mass of dodecanethiol were mixed and dissolved, and 0.5 parts by mass of an anionic surfactant (Neogen SC manufactured by Daiichi Kogyo Seiyaku) was dissolved in 400 parts by mass of ion-exchanged water. Emulsion polymerization was carried out in a flask, and while slowly mixing for 10 minutes, 50 parts by mass of ion-exchanged water in which 0.5 parts by mass of ammonium persulfate was dissolved as an initiator was added.

After purging with nitrogen, the flask was heated in an oil bath while stirring until the contents reached 70°C, and emulsion polymerization was continued for 5 hours to obtain a resin dispersion.

Thereafter, coating resin 1 was obtained by drying the resin dispersion by spray drying. The weight average molecular weight of Coating Resin 1 was 350,000.

<Preparation of carrier particles 1>
100 parts by mass of the core material particles 1 prepared above as core material particles and 4.5 parts by mass of the coating resin 1 were put into a high-speed stirring mixer with horizontal stirring blades, and the peripheral speed of the horizontal rotary blade was 8 m/ After mixing and stirring at 22°C for 15 minutes under conditions such as After cooling to room temperature, carrier particles 1 were produced.

<Preparation of developer>
Toner particles 1 and carrier particles 1 prepared as described above were mixed so that the toner concentration was 9% by mass to prepare developer 1. A V-type mixer (manufactured by Tokuju Kosho Co., Ltd.) was used as a mixer, and the mixture was mixed at 25° C. for 30 minutes.

<Preparation of developers 2 to 17>
Developers 2 to 17 were produced in the same manner as in the production of toner particles 1, except that toner particles 2 to 17 were used instead of toner particles 1.

[evaluation]
The prepared developer and photoreceptor were mounted in the cyan position of an image forming apparatus AccurioPress C3070 (manufactured by Konica Minolta) in the combinations shown in Table VI and evaluated.

First, the initial fine line reproducibility and the photosensitive layer thickness were measured in an environment of a temperature of 10° C. and a humidity of 15% RH.
Next, a printing durability test was conducted in which 1 million A4 images with a printing rate of 5% were continuously printed on both sides by horizontal feeding on neutral paper.

After the above printing durability test, fine line reproducibility and photosensitive layer thickness were measured.
The fine line reproducibility and the amount of photoreceptor wear were evaluated according to the following evaluation criteria, and ◎, ○, and △ were considered to be acceptable.

(Fine line reproducibility)
A 2-dot wide grid image with a dot diameter of 30 μm was printed on the entire surface of A4 neutral paper. The condition of the printed image was observed and evaluated as follows.
◎: The grid image has a uniform width and is clearly reproduced as a toner image (passed)
○: The width of the grid image is not uniform in some parts, but the grid is fully reproduced (passed)
△: There are some areas where the grid image is slightly missing (passed)
×: There is clearly a defect in the grid image (fail)

(Photoconductor wear amount)
In the above evaluation, 1 million images were printed, and the initial layer thickness and the layer thickness after 1 million copies were evaluated.
The layer thickness of the photosensitive layer is measured at 10 random locations at uniform thickness (excluding at least 3 cm from both ends, as the layer thickness tends to be uneven at both ends of the photoreceptor), and the average value is calculated as the average value of the photosensitive layer. Layer thickness.

The film thickness was measured using an eddy current film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GMBTE CO), and the difference in the film thickness of the photosensitive layer before and after the actual photographic test was taken as the amount of film thickness loss.
◎: Amount of wear is less than 1 μm (pass)
○: Amount of wear is 1 μm or more and less than 2 μm (pass)
△: Amount of wear is 2 μm or more and less than 3 μm (pass)
×: Depletion amount is 3 μm or more (fail)

From the results shown in Table VI, it can be seen that the examples using the photoreceptor and developer (toner) according to the present invention had better overall evaluation performance than the comparative examples.

1 Undercoat layer 2 Charge generation layer 3 Charge transport layer 4 Conductive support 5 Photosensitive layer 7 Electrophotographic photoreceptor 1Y, 1M, 1C, 1K Electrophotographic photoreceptor 2Y, 2M, 2C, 2K Charging means 3Y, 3M, 3C , 3K Exposure means 4Y, 4M, 4C, 4K Developing means 5Y, 5M, 5C, 5K Primary transfer roller (primary transfer means)
5b Secondary transfer roller (secondary transfer means)
6Y, 6M, 6C, 6K, 6b Cleaning means 10Y, 10M, 10C, 10K Image forming unit 20 Paper feeding cassette 21 Paper feeding means 22A, 22B, 22C, 22D Intermediate roller 23 Registration roller 24 Fixing means 25 Paper ejection roller 26 Ejection Paper tray 70 Intermediate transfer body unit 71 to 74 Roller 77 Endless belt-like intermediate transfer body 80 Housing 82R, 82L Support rail 100 Image forming device 241 Heating roller 242 Pressure roller

Claims (3)

An image forming method using an electrostatic image developing toner and an electrophotographic photoreceptor and comprising at least a charging step, an exposure step, a developing step, and a transfer step,
The electrophotographic photoreceptor has a photosensitive layer,
The photosensitive layer contains a compound having a structure represented by the following general formula (1) and a compound having a structure represented by the following general formula (2) as a charge transport substance ,
The electrostatic image developing toner contains titanic acid compound particles whose primary particles have a number average diameter of 10 to 80 nm and silica particles whose primary particles have a number average diameter of 5 to 40 nm as external additives. Contains
The coefficient of variation of the particle size distribution of the silica particles is 20% or less,
The titanate compound particles further contain one or more elements selected from lanthanum, tin, silicon, magnesium, strontium, calcium, or barium, and
An image forming method characterized by using strontium titanate particles, calcium titanate particles, or barium titanate particles .

(In general formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and a carbon number 1 to 20 alkoxy group or an aryl group having 6 to 30 carbon atoms, and two adjacent substituents may be bonded to each other to form a hydrocarbon ring structure. p and q each independently represent 0 , 1 or 2. In the general formula (2), R ^C21 , R ^C22 , and R ^C23 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or a C 1 to 10 alkyl group. Represents an alkoxy group or an aryl group having 6 to 10 carbon atoms. ) the titanic acid compound particles contain lanthanum , and
The image forming method according to claim 1 , characterized in that the particles are strontium titanate particles, calcium titanate particles, or barium titanate particles . An image forming system using an electrostatic image developing toner and an electrophotographic photoreceptor and having at least a charging step, an exposure step, a developing step, and a transfer step, wherein the image forming method according to claim 1 or 2 is carried out. An image forming system characterized by:

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