JP2002357920A - Developing method and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing method and an image forming method by which high resolution is obtained because a toner layer is uniformly formed on a developing roll, and the fogging and the filming of a photoreceptor are hardly caused even under severe environment such as high temperature and high humidity and low temperature and low humidity. SOLUTION: In this developing device in which an electrostatic latent image formed on the surface of a latent image holding body obtained by electrification by an electrifying member with exposure is developed to a toner image, and this image forming method in which the toner image developed by the developing method is transferred to transfer material and then fixed thereon; the surface of the developing roll is constituted of a rubber elastic body, and the surface roughness in the peripheral direction of the developing roll is <=10 μm and the surface roughness in the shaft direction thereof is <=10 μm, and then toner whose content of boron or phosphorus is 0.1 to 100 ppm is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a developing method and an image forming method.

[0002]

2. Description of the Related Art Conventionally, an image forming method using an electrophotographic method, such as an electrophotographic printer, includes a charging step of uniformly and uniformly charging the surface of a photosensitive drum as a latent image holding member by a charging device. An exposing step of forming an electrostatic latent image on a surface of a charged photoreceptor by a latent image forming apparatus such as a laser beam irradiating apparatus; a developing step of developing the electrostatic latent image using toner by a developing device; And a fixing step of fixing the transferred toner image to a transfer material.

The developing device used in the developing step of such an image forming method has a developing roll. When the developing roll rotates in the developing device, the toner in the developing device adheres to the outer peripheral surface due to electrostatic force or the like due to friction. A part of the toner adhered to the outer peripheral surface of the developing roll is selectively moved to the surface of the photosensitive drum according to the latent image pattern when the surface of the developing roll comes into contact with or comes close to the surface of the photosensitive drum. The electrostatic latent image on the drum is developed, and a toner image is formed on the surface of the photosensitive drum. This toner image is transferred to a transfer material to form an image.

[0004] In such a developing roll, it is important to attach toner so as to form a uniform and thin layer on the outer peripheral surface of the developing roll. If the toner does not uniformly adhere to the outer peripheral surface of the roll, when the electrostatic latent image is developed on the surface of the photosensitive drum, fogging of the photoconductor or paper occurs. In addition,
Photoconductor fog is a phenomenon in which toner having a polarity opposite to the polarity of the toner to be attached to the photosensitive drum adheres to the photosensitive drum, making uniform charging difficult and causing problems such as deterioration in image quality. Paper fogging is a phenomenon in which toner having a polarity opposite to the charge of the photosensitive drum adheres to a non-image portion of the photosensitive drum and is transferred to a transfer material, causing a problem such as deterioration of image quality.

In a conventional developing roll, the surface has a volume resistivity of 10 so that the toner is easily attached electrostatically.
^A material composed of an elastic body exceeding ⁸ Ω · cm has been developed. Further, there has been proposed a developing roll provided with means for controlling the surface potential of the developing roll and capable of adjusting the amount of toner adhered.

However, in these developing rolls,
It was difficult to form a uniform toner layer, and there was a possibility that the above-mentioned fogging of the photoconductor and the fogging of the paper would still occur.

[0007]

In order to solve the above-mentioned problems, the present applicant has proposed that the surface is made of a rubber elastic body, the surface has a surface roughness of 10 μm or less, and the surface has an axial surface roughness of 10 μm or less. An image forming apparatus having a developing roll having a surface roughness in the direction of 10 μm or less has been proposed. However, it has been found that in a severe environment of high temperature and high humidity and low temperature and low humidity, it is still impossible to suppress the photoreceptor fogging and filming, and an object of the present invention is to solve these problems.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the developing roll of the developing device constituting the image forming apparatus has a specific surface roughness. It was found that the above object can be achieved by using and a specific toner.
The present invention has been completed.

Thus, according to the present invention, there is provided a developing method for developing an electrostatic latent image formed by exposure on the surface of a latent image holding member obtained by being charged by a charging member into a toner image. The surface of the developing roll is made of a rubber elastic material, the surface has a surface roughness of 10 μm or less, the surface has an axial surface roughness of 10 μm or less, and the toner has a boron or phosphorus content of 0.1 μm or less. There is provided a developing method of 1 to 100 ppm, and an image forming method in which a toner image developed by this method is transferred onto a transfer material and then fixed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A developing roll used in the developing method of the present invention selectively removes a part of the toner adhered to the outer periphery in a predetermined pattern corresponding to a latent image on the outer peripheral surface of a latent image holding member. A developing roll for performing development by moving to at least a surface having a rubber elastic body, a surface circumferential surface roughness of 10 μm or less, and a surface axial surface roughness of 10 μm or less. is there. In the present invention, the surface roughness in the circumferential direction and the surface roughness in the axial direction may approach zero as long as it is 10 μm or less, but is preferably about 6 to 8 μm in consideration of mass productivity and economy. .

If the surface roughness in the circumferential direction is larger than 10 μm, a uniform toner layer cannot be formed along the circumferential direction, and the resolution may be deteriorated. Also,
If the surface roughness in the axial direction is larger than 10 μm, a uniform toner layer cannot be formed along the axial direction, and the resolution may be deteriorated.

In the present invention, the surface roughness refers to the surface of the roll traced in a measuring direction (circumferential or axial direction) with a stylus, and its movement is recorded, and the unevenness of the surface is expressed as a surface roughness curve. , 5 points from the higher side and 5 points from the lower side of the curve were selected and averaged. The difference between the respective averages is defined as the surface roughness (Rz).

As shown in FIG. 1, the outer periphery of a conductive shaft 71 of this developing roll is covered with a rubber elastic body 72. The conductive shaft 71 is made of, for example, a metal such as stainless steel. In order to cover the outer periphery of the conductive shaft 71 with the rubber elastic body 72, the rubber elastic body 72 may be applied to the outer periphery of the conductive shaft 71 by means such as press molding and extrusion molding. In this case, extrusion molding is particularly preferable. This is because it is suitable for mass production and, unlike press molding, a split mold line is not formed.

The rubber elastic material constituting the surface of the developing roll is not particularly limited, but includes styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylic rubber, epichlorohydrin rubber, urethane rubber, silicone Rubber and the like are preferably used, and epichlorohydrin rubber, acrylonitrile-butadiene copolymer rubber, and a blend of epichlorohydrin rubber and acrylonitrile-butadiene copolymer rubber are preferably used.

As a means for making the surface of the developing roll have a surface roughness in the above-mentioned range, a means for polishing the outer peripheral surface of the rubber elastic body with a cylindrical cutting machine or the like can be used. Polishing is performed first with a coarse cutting file or whetstone, and finally with a fine file or whetstone or wet polishing.

When the developing roll is composed of a conductive shaft and a rubber elastic body, the electric resistance between the surface of the rubber elastic body and the surface of the conductive shaft is 10 ⁵ to 10 ⁸ Ω (5
00V voltage applied) or volume resistivity 10 ⁷ -10 ¹⁰
It is preferably Ω · cm. If the resistance of the rubber elastic body is too low, current may flow from the developing roll to the latent image carrier (photosensitive drum), and the charge of the toner may leak to the developing roll. On the other hand, if the resistance of the rubber elastic body is too high, it is not preferable because the surface may be charged due to friction and adversely affect development.

In the developing method of the present invention, an electrostatic latent image formed by exposure on the surface of a latent image holding member obtained by charging with a charging member is developed into a toner image.

In the image forming method of the present invention, the toner image obtained by the above-described developing method is transferred to a transfer material and then fixed.

Hereinafter, the developing method and the image forming method of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a view showing an example of an image forming apparatus to which the developing method and the image forming method of the present invention can be applied. As shown in FIG. 2, the image forming apparatus has a photosensitive drum 1 as a latent image holding member, which is rotatably mounted in the direction of arrow A.

The photosensitive drum 1 has a photoconductive layer provided on a conductive support drum, and the photoconductive layer is made of, for example, an organic photoconductor, a selenium photoconductor, a zinc oxide photoconductor, an amorphous silicon photoconductor, or the like. , Preferably an organic photoreceptor. Examples of the resin that binds the photoconductive layer to the conductive support drum include a polyester resin, an acrylic resin, a polycarbonate resin, a phenol resin, and an epoxy resin, and a polycarbonate resin is preferable.

Around the photosensitive drum 1, along a circumferential direction thereof, a charging roll 3 as a charging member, a laser beam irradiation device 4 as an exposure device, a developing device 11, and a transfer roll 5
And a cleaning device 2.

Charging means that the photosensitive drum 1 is charged by a charging member.
Is positively or negatively charged uniformly. As a charging method for the charging member, in addition to the charging roll 3 shown in FIG. 2, there are a contact charging method for charging with a fur brush, a magnetic brush, a blade, and the like, and a scorotron type non-contact charging method using corona discharge. It is also possible to replace them.

Exposure is to irradiate the surface of the photosensitive drum with light corresponding to an image signal by a laser light irradiation device 4 as an exposure device as shown in FIG. This is to form an electrostatic latent image. Such a laser beam irradiation device 4 is composed of, for example, a laser beam irradiation device and an optical lens. In addition, as an exposure apparatus, there is an LED irradiation apparatus.

Developing is a process in which the developing device 11 attaches toner to the electrostatic latent image formed on the surface of the photosensitive drum 1 by exposure. In the reversal development, the toner is attached only to the light irradiation section. In the normal development, a bias voltage is applied between the developing roll 7 and the photosensitive drum 1 so that the toner can be attached only to the light non-irradiated portion.

The developing device 11 shown in FIG. 2 is a developing device used in a one-component contact developing system, and has a developing roll 7 and a supply roll 9 in a casing 12 in which a toner 10 is stored. The developing roll 7 is arranged so as to partially contact the photosensitive drum 1, and rotates in the direction B opposite to the photosensitive drum 1. The supply roll 9 contacts the developing roll 7 and rotates in the same direction C as the developing roll 7 to supply the toner 10 to the outer periphery of the developing roll 7. Other development methods include a one-component non-contact development method, a two-component contact development method, and a two-component non-contact development method.

In the casing of the developing device, a toner supply roll may be rotatably arranged close to the developing roll in order to make toner adhere to the outer peripheral surface of the developing roll. It is preferable that a bias voltage is applied to the conductive shaft of the developing roll.

In the case of reversal development, a voltage having the same polarity as that of the electrostatic latent image on the latent image holding member is applied to the conductive shaft of the developing roll.

Transfer means transferring the toner image formed on the surface of the photosensitive drum formed by the developing device 11 to a transfer material 6 such as paper by applying a transfer voltage having a polarity opposite to that of the toner by the transfer device. Usually, a transfer roll 5 as shown in FIG. 2 is used as a transfer device, but there are also belt transfer and corona transfer.

Fixing is to fix the toner image transferred onto the transfer material 6 such as paper so that the toner image is not separated from the transfer material. Normally, heat fixing is performed by two rolls (a heating roll 13 and a pressure roll 14) as shown in FIG. 2, but in addition, another heating roll is used instead of the heating roll 13. Pressure fixing, flash fixing using a xenon lamp without using a roll, or solvent fixing using an organic solvent.

Although it is not necessary to perform cleaning at the same time as the development, a cleaning step for removing the toner remaining on the surface of the photosensitive drum by the cleaning device 2 may be provided between the transfer roll and the charging member. preferable. Usually, a cleaning blade is used for this cleaning device.
Cleaning with a magnetic brush, a cleaning roll, static electricity or the like has also been proposed.

In the image forming apparatus shown in FIG. 2, the surface of the photosensitive drum 1 is uniformly charged to the negative polarity by the charging roll 3 and then an electrostatic latent image is formed by the laser beam irradiation device 4. The developing device 11 develops the toner image.

Subsequently, the toner image on the photosensitive drum 1 is transferred to a transfer material 6 such as paper by a transfer roll 5, and is fixed to the transfer material by two fixing rolls (a heating roll 13 and a pressure roll 14). Is done. If necessary, the transfer residual toner remaining on the surface of the photosensitive drum is cleaned by the cleaning device 2, and then the next image forming cycle is started.

Although the image forming apparatus shown in FIG. 2 is for monochrome, the developing method and the image forming method of the present invention can be applied to a color image forming apparatus such as a copying machine or a printer for forming a color image. .

As a color image forming apparatus, a multi-developing system in which a multi-color toner image is developed on a photoconductor and is collectively transferred to a transfer material, after a single-color toner image is developed on the photoconductor, There is a multiple transfer system in which transfer to a transfer material is repeated for the number of colors of the color toner. In the multiple transfer system, a transfer material is wound around a transfer drum and a transfer is performed for each color. A primary transfer is performed for each color on an intermediate transfer body, and a multicolor image is formed on the intermediate transfer body. After the formation, the intermediate transfer system that performs the secondary transfer at once, the developing device is arranged in tandem around the photoconductor,
There is a tandem system in which a transfer material is sucked and conveyed by a transfer conveyance belt and each color is sequentially transferred to the transfer material. Among these, a tandem type image forming apparatus capable of performing image formation at high speed is preferable.

FIG. 3 is a schematic view showing an example of a tandem type color image forming apparatus to which the image forming method of the present invention can be applied. In the tandem type color image forming apparatus, an image forming section in which the laser beam irradiating device 4, the photosensitive drum 1, the developing device 11, and the cleaning device 2 are set is provided by the number of toner colors to be used. Each image forming unit is normally arranged in the order of yellow, magenta, cyan, and black along the transport belt 15, and the image formed by each image forming unit is adsorbed on the transport belt and transported. The image is transferred onto the transfer material 7 by the transfer roll 5 in a superimposed manner and is fixed. As described above, the transfer material is generally transported by a transport belt, but may be transported by being attracted to a transfer drum. in this case,
Each image forming section is arranged in order along the transfer drum.

The letters Y, M, C, and K shown in FIG. 3 correspond to the colors of the toner in each image forming unit, namely, yellow, magenta, cyan, and black.

The toner used in the present invention contains boron or phosphorus, particularly preferably boron. Their content is 0.1-100 ppm, preferably 0.2-50 ppm.
ppm, more preferably 0.5 to 10 ppm.
If the boron or phosphorus content is small, poor cleaning on the photoreceptor occurs and image quality is likely to occur,
Conversely, if the content is large, fogging occurs when the temperature or humidity fluctuates, and the image quality deteriorates.

The method for incorporating boron or phosphorus into the toner includes: i) adding a boron or phosphorus compound at the time of melting and kneading the binder resin; ii) polymerizing in the presence of the boron or phosphorus compound; iii) pulverizing Post-addition to a toner produced by polymerization, polymerization, association or the like. Among them, it is preferable to apply the method of ii) of polymerizing in the presence of a boron or phosphorus compound because the stability during polymerization is improved.

The boron or phosphorus content is a value measured by the following method. That is, about 5 g of precisely weighed toner is put in a 100 ml plastic container, and ion-exchanged water 50
The resulting mixture was shaken to disperse the toner. Next, the container is immersed in warm water of 90 ° C., and the entire container is heated.
Shake for another 30 minutes. After filtration through a 0.4 μm filter, the amount of boron or phosphorus dissolved in the filtrate was quantified by ion chromatography, and the measured value was taken as the content in the toner.

The volume average particle size (dv) of the toner used in the present invention is not particularly limited, but is usually 2 to 10 μm, preferably 2 to 9 μm, more preferably 3 to 8 μm. In addition, volume average particle diameter (dv) / number average particle diameter (d
Although p) is not particularly limited, it is usually 1.7 or less, preferably 1.5 or less, more preferably 1.3 or less. Two
The toner having a number average particle diameter of 4 μm is preferably 4 to 8% by number. If the amount is smaller than this, the resolution may be reduced, and if it is larger, the fluidity may be reduced.

Further, the sphericity (Sc / Sr) of the value obtained by dividing the area (Sc) of the circle having the diameter by the absolute maximum length of the particle by the substantial projected area (Sr) of the particle is 1 to 1.3. Preferably, the toner is spherical in nature.

The preferred toner for use in the present invention has a volume resistivity (log (Ω · cm)) measured by a dielectric loss meter.
However, it is usually 10 to 13, preferably 10.5 to 12.5. If the volume specific resistance is small, fogging may occur, and if it is large, cleaning failure may occur.

The preferred toner used in the present invention has a softening temperature (hereinafter sometimes referred to as Ts) by a flow tester of usually 50 to 80 ° C., preferably 60 to 70 ° C.
° C, and the flow start temperature (hereinafter sometimes referred to as Tfb) is usually 90 to 150 ° C, preferably 100 to 1 ° C.
30 ° C. If the softening temperature is low, the storability may decrease, and if it is too high, the fixability may decrease. If the flow start temperature is low, the hot offset resistance may decrease, and if it is high, the fixability may decrease.

The glass transition temperature by a differential scanning calorimeter (hereinafter, also referred to as DSC) is usually from 0 to 80 ° C.
Preferably it is 40-60 degreeC. If the glass transition temperature is low, the storability may decrease, and if it is too high, the fixability may decrease.

The toner used in the present invention may be so-called core-shell type (also called capsule type) particles obtained by combining two different polymers inside (core layer) and outside (shell layer) of the particles. it can. In the core-shell type toner, by lowering the fixing temperature and preventing aggregation during storage by forming a shell (shell layer) with a material having a higher softening point on the surface of the material having a lower softening point inside (core layer). It is preferable because it can be balanced with. As a method for obtaining the core-shell toner, a method such as a spray drying method, an interface reaction method, an in situ polymerization method, and a phase separation method can be adopted. In particular, an in situ polymerization method or a phase separation method is preferable because of high production efficiency. The core particles of the core-shell toner may be obtained by a pulverization method, or may be obtained by a polymerization method, an association method, or a phase inversion emulsification method.

In the case of a core-shell toner, the volume average particle size of the core particles is not particularly limited, but is usually 2 to 10 μm.
Preferably it is 2 to 9 μm, more preferably 3 to 8 μm. In addition, volume average particle diameter (dv) / number average particle diameter (d
Although p) is not particularly limited, it is usually 1.7 or less, preferably 1.5 or less, more preferably 1.3 or less.

The weight ratio between the core layer and the shell layer of the core-shell type toner is not particularly limited, but is usually 80/20 to 9/9.
Used at 9.9 / 0.1.

If the ratio of the shell layer is smaller than the above-mentioned ratio, the storability deteriorates. On the contrary, if the ratio is larger than the above-mentioned ratio, it may be difficult to fix at a low temperature.

The average thickness of the shell layer of the core-shell toner is usually from 0.001 to 1 μm, preferably from 0.003 to 1 μm.
It is 0.5 μm, more preferably 0.005 to 0.2 μm. When the thickness is large, the fixability is reduced, and when the thickness is small, the storability may be reduced. It is not necessary that all the surfaces of the core particles forming the core-shell type toner are covered with the shell layer.

The core particle diameter of the core-shell toner and the thickness of the shell layer can be observed by an electron microscope.
It can be measured by directly measuring the size and shell thickness of randomly selected particles from the observation photos,
When it is difficult to observe the core layer and the shell layer with an electron microscope, it can be calculated from the particle size of the core particles and the amount of the polymerizable monomer forming the shell layer used in the production of the toner particles.

The toner used in the present invention contains a binder resin, a colorant, and a charge control agent, and may contain other additives such as a release agent and a magnetic material, if necessary.

As the binder resin, a thermoplastic resin which has been widely used for a toner is conventionally used. For example, polymers of styrene such as polystyrene and polyvinyltoluene and substituted products thereof; styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-acrylonitrile copolymer, Styrene copolymers such as styrene-maleic acid copolymer and styrene-maleic acid ester copolymer; polymethyl methacrylate, polyester, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, and fat Group or alicyclic hydrocarbon resins, aromatic petroleum resins, etc., and these can be used alone or in combination.

As the coloring agent, any pigment and / or dye can be used in addition to carbon black, titanium black, magnetic powder, oil black, and titanium white. Black carbon black has a primary particle size of 20 to
Those having a thickness of 40 nm are preferably used. If it is less than 20 nm, the carbon black may aggregate and not uniformly disperse in the toner, resulting in a toner with much fog. On the other hand, when it is larger than 40 nm, a large amount of a polyvalent aromatic hydrocarbon compound such as benzopyrene generated during the production of carbon black remains in the toner in a large amount, which may cause environmental safety problems.

When a full-color toner is obtained, a yellow colorant, a magenta colorant and a cyan colorant are usually used.

As the yellow colorant, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I.
I. Pigment Yellow 3, 12, 13, 14, 15,
17, 62, 65, 73, 83, 90, 93, 97, 1
20, 138, 155, 180 and 181.

As the magenta colorant, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I.
I. Pigment Red 48, 57, 58, 60, 63,
64, 68, 81, 83, 87, 88, 89, 90, 1
12, 114, 122, 123, 144, 146, 14
9, 163, 170, 184, 185, 187, 20
2, 206, 207, 209, 251, C.I. I. Pigment Violet 19 and the like.

As the cyan coloring agent, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds and the like can be used. Specifically, C.I. I. Pigment Blue 2,
3, 6, 15, 15: 1, 15: 2, 15: 3, 15:
4, 16, 17, and 60, and the like.

The amount of such a coloring agent is usually 1 to 10 parts by weight based on 100 parts by weight of the binder resin.

As the charge control agent, a charge control agent conventionally used for a toner can be used. For example, Bontron N01 (manufactured by Orient Chemical Industries), Nigrosine Base EX (manufactured by Orient Chemical Industries), Spiron Black TRH (manufactured by Hodogaya Chemical Industries), T-7
7 (manufactured by Hodogaya Chemical Industries), Bontron S-34 (manufactured by Orient Chemical Industries), Bontron E-81 (manufactured by Orient Chemical Industries), Bontron E-84 (manufactured by Orient Chemical Industries), COPY CHARGE NX (Clariant) Co., Ltd.), COPY CHARGE NEG
(Manufactured by Clariant Co., Ltd.), and JP-A-63-60458 and JP-A-3-175.
Quaternary ammonium (salt) group-containing copolymers described in JP-A-456-456, JP-A-3-243954, JP-A-11-15192, and the like;
No. 4, JP-A-3-15858, etc., a sulfonic acid (salt) group-containing copolymer can be synthesized and used as a charge control agent (charge control resin).

Among these, it is preferable to use a charge control resin. The charge control resin is preferable because it has high compatibility with the binder resin, is colorless, and can provide a toner having stable chargeability even in high-speed color continuous printing.

The glass transition temperature of the charge control resin is usually 4
The temperature is from 0 to 80C, preferably from 45 to 75C, and more preferably from 45 to 70C. If it is lower than this, the preservability of the toner becomes worse, and if it is higher, the fixability may be lowered.

The amount of the charge controlling agent is usually 0.01 to 20 parts by weight, preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the binder resin.
It is a ratio of 1 to 10 parts by weight.

Examples of the release agent include low-molecular-weight polyolefin waxes such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, and low-molecular-weight polybutylene; natural plant waxes such as candelilla, carnauba, rice, wood wax, and jojoba; paraffin; Crystallin,
Examples include petroleum waxes such as petrolactam and modified waxes thereof; synthetic waxes such as Fischer-Tropsch wax; polyfunctional ester compounds such as pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, and dipentaerythritol hexamyristate.

These can be used alone or in combination of two or more.

Of these, synthetic waxes (particularly Fischer-Tropsch wax), terminal-modified polyolefin waxes, petroleum waxes, and polyfunctional ester compounds are preferred. Among the polyfunctional ester compounds, in a DSC curve measured by a differential scanning calorimeter, the endothermic peak temperature at the time of temperature rise is 30 to 200 ° C, preferably 40 to 200 ° C.
Polyester compounds such as pentaerythritol ester having a temperature in the range of 160 ° C., more preferably in the range of 50 to 120 ° C., and dipentaerythritol ester having the endothermic peak temperature in the range of 50 to 80 ° C., are fixed and peeled as toner. It is particularly preferable from the viewpoint of the balance of properties. Among them, it has a molecular weight of 1,000 or more, dissolves at least 5 parts by weight at 25 ° C with respect to 100 parts by weight of styrene, and has an acid value of 10 mg / KO.
Those having H or less are more preferable because they have a remarkable effect on lowering the fixing temperature. The endothermic peak temperature is ASTM D3418.
This is the value measured by -82.

The release agent is used in an amount of usually 0.5 to 50 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the binder resin.

The toner used in the present invention may contain a magnetic material. As the magnetic material, for example, magnetite, γ-iron oxide, ferrite, iron oxide such as iron-rich ferrite; metals such as iron, cobalt, nickel or these metals and aluminum, cobalt, copper, lead,
Magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium,
Examples include alloys with metals such as titanium, tungsten, and vanadium, and mixtures thereof.

The toner used in the present invention preferably has an external additive attached or buried on the surface of the toner particles. Examples of the external additive include inorganic particles and organic resin particles, and it is preferable to use inorganic particles and organic resin particles in combination. In order for the external additive to adhere to the polymer particles, the external additive and the polymer particles are usually charged into a mixer such as a Henschel mixer and stirred.

The toner of a further preferred embodiment used in the present invention has silica fine particles (A) having an average primary particle size of 5 to 20 nm, preferably 7 to 15 nm, and an average primary particle size of 0.05 to 0.05 nm. -1 μm, preferably 0.1-0.
An external additive containing organic or inorganic fine particles (C) of 8 μm is added to toner particles. The external additive has an average primary particle size of 20 to 60 nm, preferably 25 to 60 nm.
More preferably, it contains 50 nm of silica fine particles (B). By adhering or embedding an external additive on the surface of the particles, the chargeability, fluidity, storability and the like of the particles can be adjusted.

If the average particle diameter of the silica fine particles (A) is small, the photoreceptor is likely to cause filming. If the average particle diameter of the silica fine particles (B) is small, the photoreceptor tends to cause filming. When the average particle size of the organic or inorganic fine particles (C) is small, the polishing property is reduced, and when the average particle size is large, the fluidity is sometimes reduced.

The silica fine particles (A) or silica fine particles (B) are not particularly limited, but are preferably subjected to a hydrophobic treatment. Hydrophobized silica fine particles are generally commercially available, but can also be obtained by hydrophobizing with a silane coupling agent or silicone oil.

As a method of the hydrophobizing treatment, a method of dropping or spraying a silicone oil or the like as a treating agent while stirring the fine particles at a high speed, or a method of dissolving a treating agent and dispersing the fine particles in an organic solvent being stirred. After the addition and mixing, a method of performing a heat treatment or the like can be given. In the former case, the treating agent may be diluted with an organic solvent or the like.

The degree of hydrophobicity is from 20 to 90% as measured by the methanol method. Preferably 40 to 80
%. If the degree of hydrophobicity is small, it is easy to absorb moisture under high humidity,
If the degree of hydrophobicity is too high, sufficient polishing properties may not be obtained.

The organic fine particles are not particularly limited, but the compound constituting the fine particles usually has a glass transition temperature or melting point of 80 to 80 from the viewpoint of suppressing blocking between the particles.
The temperature is 250 ° C, preferably 90 to 200 ° C.

Examples of the compound constituting the organic fine particles include a methyl methacrylate polymer and a styrene-methyl methacrylate copolymer.

The sphericity (Sc / Sr) obtained by dividing the area (Sc) of a circle whose diameter is the absolute maximum length of the particle by the substantial projected area (Sr) of the particle is not particularly limited.
1.3, preferably 1-1.2. If the sphericity is large, the transferability may decrease.

Examples of the inorganic fine particles include silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, barium titanate, and strontium titanate, and those obtained by subjecting them to surface treatment with tin or antimony, and the like. No.

The addition amount of the silica fine particles (A) is not particularly limited, but is usually 0.1 to 100 parts by weight of the toner particles.
It is 1 to 3 parts by weight, preferably 0.2 to 2 parts by weight. If the amount is small, the fluidity may be reduced and fuzz may occur. Conversely, if the amount is large, the fluidity may be increased and fog may be easily caused.

The addition amount of the silica fine particles (B) is not particularly limited, but is usually 0.1 to 100 parts by weight of the toner particles.
It is 1 to 1 part by weight, preferably 0.2 to 0.7 part by weight. If this amount is small, the polishing property may decrease and filming may occur, and if it is large, the fluidity decreases,
In some cases, it may become easier to wear.

The addition amount of the organic or inorganic fine particles (C) is not particularly limited, but is based on 100 parts by weight of the toner particles.
It is usually 0.1 to 2 parts by weight, preferably 0.2 to 1 part by weight. If the amount is less than this, filming may occur. On the other hand, if the amount is more than this, the fluidity may be reduced, and the film may be easily blurred.

The attachment or burying of the external additive is usually carried out by stirring the external additive and the toner particles in a mixer such as a Henschel mixer.

The toner used in the present invention is not limited by its manufacturing method. For example, in a thermoplastic resin serving as a binder resin component, after a colorant, a charge control agent, a release agent, and the like are melt-mixed and uniformly dispersed to form a composition, the composition is pulverized and classified. A pulverization method for obtaining a toner by dissolving or dispersing a colorant, a charge control agent, a release agent, and the like in a polymerizable monomer that is a binder resin raw material, and after adding a polymerization initiator,
A polymerization method of suspending in an aqueous dispersion medium containing a dispersion stabilizer, heating to a predetermined temperature to start polymerization, and after the polymerization is completed, a polymerization method of obtaining a toner by filtering, washing, dehydrating and drying,
Particles of the binder resin obtained by emulsion polymerization or suspension polymerization, particles containing a colorant and a charge control agent are associated with each other, and the associated particles are subjected to heat treatment, filtration, and drying to form a toner. The resulting association method, a hydrophilic group-containing resin as a binder resin, a colorant, a charge control agent and the like are added and dissolved in an organic solvent, and then the resin is neutralized, phase-inverted, and then dried. The toner can be produced by a phase inversion emulsification method or the like for obtaining a toner. From the viewpoint of obtaining a toner that provides an image with good dot reproducibility, it is preferably produced by a polymerization method, and more preferably polymerized in the presence of a compound containing boron or phosphorus.

In the polymerization method, the polymerization of the polymerizable monomer composition can be carried out by any of emulsion polymerization, suspension polymerization, precipitation polymerization, and soap-free polymerization. The suspension polymerization method is preferred from the viewpoint of improving the transferability and transferability.

As a polymerizable monomer for obtaining a binder resin, a monovinyl monomer, a crosslinkable monomer, a macromonomer and the like can be mentioned. This polymerizable monomer is polymerized to become a binder resin component in the polymer particles.

Specific examples of the monovinyl monomer include aromatic vinyl monomers such as styrene, vinyltoluene and α-methylstyrene; (meth) acrylic acid; methyl (meth) acrylate, and (meth) acrylic acid. Ethyl, propyl (meth) acrylate, butyl (meth) acrylate, (meth)
Derivatives of (meth) acrylic acid such as 2-ethylhexyl acrylate, cyclohexyl (meth) acrylate, isobonyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and (meth) acrylamide; ethylene,
Monoolefin monomers such as propylene and butylene; and the like.

The monovinyl monomer may be used alone or in combination of a plurality of monomers. Of these monovinyl monomers, an aromatic vinyl monomer alone, or a combination of an aromatic vinyl monomer and a derivative of (meth) acrylic acid is preferably used.

The use of a crosslinkable monomer or a crosslinkable polymer together with the monovinyl monomer is effective for improving hot offset. The crosslinkable monomer is a monomer having two or more polymerizable carbon-carbon unsaturated double bonds. In particular,
Aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; diethylenically unsaturated carboxylic esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate;
Examples thereof include compounds having two vinyl groups such as N, N-divinylaniline and divinyl ether, and compounds having three or more vinyl groups such as pentaerythritol triallyl ether and trimethylolpropane triacrylate. Crosslinkable polymer is a polymer having two or more vinyl groups in the polymer, specifically, polyethylene, polypropylene, polyester and polyethylene glycol having two or more hydroxyl groups in the molecule. Esters obtained by subjecting a polymer to a condensation reaction with an unsaturated carboxylic acid monomer such as acrylic acid or methacrylic acid can be mentioned. These crosslinkable monomers and crosslinkable polymers can be used alone or in combination of two or more. The amount used is usually 10 parts by weight or less, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the monovinyl monomer.

It is preferable to use a macromonomer together with the monovinyl monomer, because the balance between the storability and the low-temperature fixability is improved. The macromonomer has a vinyl polymerizable functional group at the terminal of the molecular chain, and is an oligomer or polymer having a number average molecular weight of usually 1,000 to 30,000. When a polymer having a small number average molecular weight is used, the surface portion of the polymer particles becomes soft, and the storage stability decreases. Conversely, when a polymer having a large number average molecular weight is used, the meltability of the macromonomer is deteriorated, and the fixability is lowered.

Examples of the vinyl polymerizable functional group at the terminal of the macromonomer molecular chain include an acryloyl group and a methacryloyl group, and a methacryloyl group is preferable from the viewpoint of easy copolymerization.

The macromonomer preferably has a higher glass transition temperature than the polymer obtained by polymerizing the monovinyl monomer.

Specific examples of the macromonomer used in the present invention include polymers obtained by polymerizing styrene, styrene derivatives, methacrylates, acrylates, acrylonitrile, methacrylonitrile, etc., alone or in combination of two or more. A macromonomer having a polysiloxane skeleton can be exemplified, and among them, a polymer obtained by polymerizing a hydrophilic monomer, particularly a methacrylic ester or an acrylic ester, alone or in combination thereof is preferable.

When a macromonomer is used, the amount thereof is usually based on 100 parts by weight of the monovinyl monomer.
0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight,
More preferably, it is 0.05 to 1 part by weight. When the amount of the macromonomer is small, the storage stability does not improve. When the amount of the macromonomer is extremely large, the fixing property is reduced.

Examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; and metal oxides such as aluminum oxide and titanium oxide. Products; metal compounds such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; water-soluble polymers such as polyvinyl alcohol, methyl cellulose, and gelatin; anionic surfactants and nonionic surfactants And amphoteric surfactants, and these may be used alone or in combination of two or more.

Among these, a dispersion stabilizer containing a metal compound, particularly a colloid of a poorly water-soluble metal hydroxide, can narrow the particle size distribution of the polymer particles, and after washing the dispersion stabilizer. Is preferable because the remaining of the film is small and an image can be clearly reproduced.

The dispersion stabilizer containing a colloid of a poorly water-soluble metal hydroxide is not limited by its production method, but the poorly water-soluble polyhydric metal compound obtained by adjusting the pH of the aqueous solution of the polyvalent metal compound to 7 or more can be used. Colloidal metal hydroxide,
In particular, it is preferable to use a colloid of a poorly water-soluble metal hydroxide generated by a reaction of a water-soluble polyvalent metal compound and an alkali metal hydroxide in an aqueous phase.

The colloid of the poorly water-soluble metal hydroxide has a number particle size distribution D50 (50% cumulative value of the number particle size distribution) of 0.1.
5 μm or less, D90 (90% cumulative value of number particle size distribution)
Is preferably 1 μm or less. When the particle size of the colloid increases, the stability of polymerization is lost, and the storage stability of the toner decreases.

The dispersion stabilizer is usually used in a proportion of 0.1 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer. If this proportion is less than 0.1 part by weight, it is difficult to obtain sufficient polymerization stability, and a polymer aggregate is easily generated. Conversely, if it exceeds 20 parts by weight, the toner particle size after polymerization becomes too fine, which is not practical.

The compound containing boron or phosphorus used in the preferred method for producing the toner used in the present invention is a water-soluble compound that is soluble in water. After dissolving in water,
It may be decomposed in water.

Compounds containing boron include boron trifluoride, boron trichloride; tetrafluoroboric acid, sodium tetrahydroborate, potassium tetrahydroborate; sodium tetraborate, sodium tetraborate decahydrate, and metaborate Sodium acid, sodium metaborate tetrahydrate, sodium peroxoborate tetrahydrate, boric acid,
Examples include potassium metaborate and potassium tetraborate octahydrate.

Examples of the phosphorus-containing compound include phosphoric acid,
Phosphonic acid, phosphinic acid, metaphosphoric acid, diphosphoric acid; sodium phosphinate monohydrate, sodium phosphonate pentahydrate, sodium hydrogen phosphonate 2.5 hydrate, sodium phosphate dodecahydrate, phosphorus Disodium hydrogen oxyate,
Disodium hydrogen phosphate decahydrate, sodium dihydrogen phosphate monohydrate, sodium dihydrogen phosphate dihydrate, sodium hypophosphate decahydrate, sodium diphosphate decahydrate, Disodium dihydrogen phosphate, disodium dihydrogen diphosphate hexahydrate, sodium triphosphate, cyclo-
Sodium tetraphosphate, potassium phosphinate, potassium phosphonate, potassium hydrogen phosphonate, potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium diphosphate trihydrate, potassium metaphosphate, and the like. . Of these, compounds containing boron, especially tetraborate, are preferred.

Examples of the polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate; 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2
-Methyl-N- (2-hydroxyethyl) propionamide, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′- Azo compounds such as azobisisobutyronitrile; di-t-butyl peroxide, dicumyl peroxide, lauroyl peroxide,
Benzoyl peroxide, t-butylperoxy-2-
Ethyl hexanoate, t-hexyl peroxy-2-
Ethyl hexanoate, t-butyl peroxypivalate, di-isopropyl peroxydicarbonate, di-
t-butyl peroxyisophthalate, 1,1 ', 3
Peroxides such as 3′-tetramethylbutylperoxy-2-ethylhexanoate and t-butylperoxyisobutyrate can be exemplified. Further, a redox initiator obtained by combining these polymerization initiators and a reducing agent can be exemplified.

Among these, it is particularly preferable to select an oil-soluble polymerization initiator soluble in the polymerizable monomer to be used, and if necessary, a water-soluble polymerization initiator can be used in combination therewith. . The polymerization initiator comprises a polymerizable monomer 10
0.1 to 20 parts by weight, preferably 0.3 to 15 parts by weight, more preferably 0.5 to 10 parts by weight, based on 0 parts by weight.

The polymerization initiator can be added in advance to the polymerizable monomer composition. In the case of suspension polymerization, after the completion of the granulation step or during the course of the polymerization reaction, or in the case of emulsion polymerization. Can be added directly to the emulsion after the emulsification step or during the polymerization reaction.

It is preferable to add a molecular weight modifier at the time of polymerization. As the molecular weight modifier, for example,
t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, 2,2,4,6,6-
Mercaptans such as pentamethylheptane-4-thiol; halogenated hydrocarbons such as carbon tetrachloride and carbon tetrabromide; and the like. These molecular weight regulators can be added before the start of polymerization or during the polymerization. The molecular weight modifier is usually 0.01 to 10 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer.
It is used in a proportion of up to 5 parts by weight.

The suspension polymerization method, which is a preferred method for producing the toner used in the present invention, is carried out in an aqueous dispersion medium containing a dispersion stabilizer, by adding a polymerizable monomer, a colorant, a charge controlling agent and other additives. The polymerizable monomer composition containing the agent is suspended and polymerized using a polymerization initiator. Other additives include the above-mentioned release agent, magnetic material, water-soluble boron or phosphorus-containing compound, molecular weight modifier and the like.

As the toner of the present invention, the toner obtained by the above-described production method can be used as it is, or a core-shell toner can be used.

Examples of the method for producing the core-shell type toner include a spray drying method, an interfacial reaction method, an in situ polymerization method and a phase separation method. A core-shell toner is obtained by using the obtained toner as a core particle and coating it with a shell layer. At this time, in situ
The polymerization method and the phase separation method are preferred from the viewpoint of production efficiency.

A method for producing a core-shell type toner by the in situ polymerization method will be described below.

A polymerizable monomer for forming a shell (polymerizable monomer for shell) and a polymerization initiator are added to an aqueous dispersion medium in which core particles are dispersed, and the mixture is polymerized to form a core-shell type. A toner can be obtained.

As a specific method of forming a shell,
A method of continuously polymerizing by adding a polymerizable monomer for shell to the reaction system of the polymerization reaction performed to obtain the core particles, or charging the core particles obtained in another reaction system, and then polymerizing the shell for polymerization. A method of adding a reactive monomer and polymerizing stepwise.

The polymerizable monomer for shell may be added to the reaction system all at once, or may be added continuously or intermittently using a pump such as a plunger pump.

As the polymerizable monomer for the shell, monomers which form a polymer having a glass transition temperature of more than 80 ° C., such as styrene, acrylonitrile and methyl methacrylate, may be used alone or in combination of two or more. be able to.

When adding the polymerizable monomer for shell, it is preferable to add a water-soluble radical initiator since a core-shell type toner can be easily obtained. When a water-soluble radical initiator is added during the addition of the shell polymerizable monomer, the water-soluble radical initiator enters the vicinity of the outer surface of the core particle to which the shell polymerizable monomer has migrated, and It is considered that a polymer (shell) is easily formed at the same time.

Examples of the water-soluble radical initiator include persulfates such as potassium persulfate and ammonium persulfate;
Azobis (4-cyanovaleric acid), 2,2′-azobis (2-amidinopropane) dihydrochloride,
Azo-based initiators such as 2,2'-azobis-2-methyl-N-1,1'-bis (hydroxymethyl) -2-hydroxyethylpropioamide; oil-soluble initiators such as cumene peroxide and redox catalysts And the like; and the like. The amount of the water-soluble radical initiator is usually 1 to 50% by weight, preferably 2 to 20% by weight, based on 100 parts by weight of the monomer for shell.

The aqueous dispersion of the obtained toner (polymer particles) is washed with sulfuric acid to adjust the pH of the system to about 5.0 with sulfuric acid. Next, after dehydrating using a filter, water washing is performed by sprinkling washing water. By repeating this, the dispersion stabilizer can be removed and the content of boron or phosphorus in the toner can be adjusted.

After the washing and dehydration are completed, the toner which can be used in the present invention is obtained by drying.

[0118]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited to these examples. In addition, parts and%
Are by weight unless otherwise specified.

In this example, evaluation was made by the following method.

[Evaluation Method] (Volume Average Particle Size) The volume average particle size (dv) and the particle size distribution of the toner, that is, the ratio (dv / dp) of the volume average particle size to the number average particle size (dp), are multisizer. (Manufactured by Beckman Coulter). The measurement by the multisizer was performed under the conditions of an aperture diameter: 100 μm, a medium: Isoton II, a concentration of 10%, and the number of measured particles: 100,000. (Number average particle diameter) The number average particle diameter of the organic fine particles is determined by taking an electron microscope image of each particle and photographing the photograph with an image processing / analysis apparatus (Luzex IID Co., Ltd., Nireco). It is an average value for 100 circle equivalent diameters measured under the condition of 2%, total processed particles: 100. (Sphericity) The sphericity (Sc / Sr) was determined by taking an electron micrograph of each particle and photographing the photograph using an image processing / analysis apparatus Luzex IID (manufactured by Nireco Corporation). 2%, total processed particles:
Under 100 conditions, a value obtained by dividing the area of the maximum outer circumference circle by the substantial cross-sectional area was measured, and the average value of the measured values was obtained.

(Resolution) Using the image forming apparatus shown in FIG. 2, one day and one white line were printed after being left for 24 hours in an (H / H) environment at a temperature of 35 ° C. and a humidity of 80%. Whether the image quality was reproducible was observed with an optical microscope, and evaluated according to the following criteria.

A: One dot line and one dot white line are reproduced.

Δ: One-dot line and one-dot white line are not reproduced, but two-dot line and two-dot white line are reproduced.

×: A 2-dot line and a 2-dot white line are not reproduced.

(Fog) Continuous printing is performed at 5% print density under the same conditions using the above-described image forming apparatus, and printing is stopped in the middle of printing (at the time of printing 100 sheets) and after printing 10,000 sheets. The toner in the non-image area on the photoreceptor after the development was adhered to an adhesive tape (Scotch Mending Tape 810-3-18 manufactured by Sumitomo 3M Limited). It was affixed to printing paper, and its whiteness (B) was measured with a whiteness meter (manufactured by Nippon Denshoku). Similarly, only the adhesive tape was stuck on the printing paper, and its whiteness (A) was measured. The fog value was calculated by the following formula: fog (%) = (AB). A smaller value indicates less fog.

(Filming) Using the above-described image forming apparatus, continuous printing was performed at a print density of 5% under the same conditions, and halftone printing was performed for every 500 sheets. The number of sheets to be counted was counted. The final print number is 20,000. Those without numbers in the table indicate that filming did not occur even after continuous printing of 20,000 sheets.

(Reference Example 1) 100 parts of styrene, 2.5 parts of sodium styrenesulfonate, 1.5 parts of sodium chloride and 4000 parts of ion-exchanged water were added to a reaction vessel equipped with a stirrer purged with nitrogen, and mixed. To 80 ° C. After heating, 2,2'-azobis [2-methyl-N-
(2-Hydroxyethyl) propionamide] (trade name: "VA-086", manufactured by Wako Pure Chemical Industries) 3% aqueous solution 5
The polymerization was started by adding 00 parts. On the way, while measuring the polymerization conversion rate, when the conversion rate reached 30%, 0.1 part of t-dodecyl mercaptan was added, and 7 minutes from the start of polymerization.
After an hour, the conversion was measured to be 98%. Next, 400 parts of methyl methacrylate was added over 15 minutes, and after continuing polymerization for another 3 hours, the polymerization was stopped by cooling with water,
An aqueous dispersion of core-shell organic fine particles was obtained. At this time,
The polymerization conversion was 100%, the number average particle diameter of the organic fine particles was 0.38 μm, and the sphericity was 1.13.

(Toner Production Example 1) 80.5 parts of styrene,
19.5 parts of butyl acrylate, 7 parts of carbon black (trade name # 25, manufactured by Mitsubishi Chemical Corporation), 1 part of a charge control agent (trade name: Spiron Black TRH, manufactured by Hodogaya Chemical Co., Ltd.), 0.3 part of divinylbenzene, Polymethacrylic acid ester macromonomer (Toa Gosei Chemical Industry Co., Ltd., AA6, Tg = 9
A homomixer (TK type, manufactured by Tokushu Kika Kogyo Co., Ltd.) capable of mixing 0.8 parts of dipentaerythritol hexamyristate and 4 parts of t-butylperoxy-2-ethylhexanoate with high shearing force. ), 12000 rpm
The mixture was stirred, mixed and uniformly dispersed at a rotation speed of to obtain a polymerizable monomer composition for a core.

On the other hand, an aqueous solution obtained by dissolving 9.8 parts of magnesium chloride (a water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water and an aqueous solution obtained by dissolving 6.9 parts of sodium hydroxide in 50 parts of ion-exchanged water were stirred. A magnesium hydroxide colloidal dispersion was prepared by gradually adding the solution below. The particle size distribution of the formed colloid was measured with a Microtrac particle size distribution analyzer (manufactured by Nikkiso Co., Ltd.). The particle size was D50 (50% cumulative value of the number particle size distribution) of 0.38 μm and D90.
(90% cumulative value of the number particle size distribution) was 0.84 μm. In the measurement using the Microtrac particle size distribution analyzer, the measurement range was 0.12 to 704 μm, the measurement time was 30 seconds, and the measurement was performed using ion-exchanged water as the medium.

To the magnesium hydroxide colloidal dispersion obtained above, 1 part of the polymerizable monomer composition for core and further 1 part of sodium tetraborate decahydrate were added, and the mixture was stirred using a propeller stirrer. Stir and mix to obtain a composition dispersion, and then use a pump to a granulator (CLEARMIX CLM-0.8S: manufactured by M-Technic) operating at a rotor rotation speed of 21,000 rpm. Then, droplets of the polymerizable monomer composition for the core were granulated. The aqueous dispersion of the granulated composition was transferred to a reactor equipped with a stirring blade.
The aqueous dispersion of the composition was heated to initiate polymerization. At this time, the temperature of the polymerization reactor jacket and the temperature of the polymerization reaction solution were measured so that the temperature of the aqueous dispersion became constant at 90 ° C., and the jacket temperature was controlled by using a cascade control method or the like.

After confirming that the polymerization conversion reached almost 100%, 2 parts of methyl methacrylate were added.
2,2 ′ azobis (2-methyl-N- (2-hydroxyethyl) -propionamide) (trade name “VA-08
6 ": Wako Pure Chemical Industries, Ltd.) An initiator solution obtained by dissolving 0.2 part in 100 parts of ion-exchanged water was added to the reaction vessel and polymerized to obtain an aqueous dispersion of polymer particles. The aqueous polymer particles are dehydrated,
After washing and drying, core-shell type toner particles were obtained.

100 parts of the toner particles obtained above were mixed with silica fine particles (A) (trade name: RX200, manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 12 nm and a hydrophobicity of 65%.
Part, silica fine particles (B) having an average particle diameter of 40 nm and a hydrophobicity of 64% (trade name: RX50, manufactured by Nippon Aerosil Co., Ltd.)
5 parts and organic fine particles having an average particle diameter of 0.38 μm and a sphericity of 1.13 synthesized in Reference Example 1 were added and mixed using a Henschel mixer to produce a toner (T1).

The toner thus obtained had a volume resistivity of 11.5 (log (Ω · cm)). The volume average particle diameter (dv) of the toner is 6.9 μm,
The ratio of the volume average particle diameter to the number average particle diameter (dv / dp) is 1.
21 and the sphericity (Sc / Sr) of the value obtained by dividing the area (Sc) of the circle having the absolute maximum length of the toner as the diameter by the substantial projected area (Sr) of the particle is 1.1, and the boron content is 1.1. Was 1.7 ppm.

(Toner Production Example 2) In the toner production example 1, except that sodium phosphate was added instead of sodium tetraborate decahydrate when the magnesium hydroxide colloidal dispersion was produced, A toner (T2) was produced in the same manner as in Example 1.

The specific volume resistance of the obtained toner is as follows.
6 (log (Ω · cm)). The volume average particle size (dv) of the toner is 7.1 μm, the ratio of the volume average particle size to the number average particle size (dv / dp) is 1.24, and the circle has the absolute maximum length of the toner as the diameter. Of the particle (Sc) divided by the actual projected area (Sr) of the particle.
r) was 1.1 and the phosphorus content was 1.9 ppm.

(Toner Production Example 3) A toner (T3) was produced in the same manner as in Toner Particle Production Example 1, except that sodium tetraborate decahydrate was not added.

The specific volume resistance of the obtained toner is as follows.
4 (log (Ω · cm)). The volume average particle size (dv) of the toner is 7.2 μm, the ratio of the volume average particle size to the number average particle size (dv / dp) is 1.25, and the circle has the absolute maximum length of the toner as the diameter. Of the particle (Sc) divided by the actual projected area (Sr) of the particle.
r) was 1.2 and contained no boron and phosphorus

(Example 1) As shown in FIG.
A rubber elastic body 22 composed of a blend rubber of epichlorohydrin rubber and acrylonitrile-butadiene copolymer rubber is provided on the outer periphery of a stainless steel shaft 21 mm.
It was formed with a thickness of 3.9 mm by extrusion molding. Thereafter, the outer peripheral surface of the rubber elastic body 22 was polished with a cylindrical cutting machine, so that the surface roughness of the outer peripheral surface was set to 8.0 μm in the axial direction and the circumferential direction.

As shown in FIG. 2, this developing roll 8 is
The photosensitive drum 1 was placed in contact with the photosensitive drum 1 such that the contact width was about 2 mm. An organic photosensitive drum was used as the photosensitive drum 1, and its outer diameter was 30 mm.

As the charging device 3, a corona discharge device that makes the surface potential of the photosensitive drum 1 uniform at about Vc = −600 V was used. As the exposure device 4, a combination of a laser device and an optical system was used. Supply roll 9
, A sponge roll made of urethane rubber having an outer diameter of 13 mm was used. The supply roll 9 was brought into contact with the developing roll 7 so that the contact width was about 2 mm.

As the layer thickness regulating blade 8, a rubber elastic body made of urethane was used, which was attached to the outer periphery of the developing roll 7 so as to have a linear pressure of about 1 g / mm. Continuous printing was performed using the toner T1 obtained in Toner Production Example 1 as the toner 10 housed in the developing device 11, and the image resolution and the fogging and filming of the photoconductor were evaluated. Table 1 shows the evaluation results.

(Examples 2 to 4, Comparative Examples 1 to 4) Evaluations were made in the same manner as in Example 1 except that the surface roughness of the developing roll and the toner used for development were changed as shown in Table 1. .
Table 1 shows the evaluation results.

[0143]

[Table 1]

Table 1 shows the following.

In the image forming methods of Comparative Examples 1 and 2 in which the surface roughness in the circumferential direction and axial direction of the developing roll is larger than the range specified in the present invention, the resolution is poor and the photosensitive member is easily fogged in a severe environment.

In the image forming methods of Comparative Examples 3 and 4 in which the toner does not contain the specific amount of boron or phosphorus specified in the present invention, fogging of the photoreceptor easily occurs under severe environment, and filming easily occurs.

In contrast, it can be seen that the image forming methods of Examples 1 to 4 of the present invention have high resolution and are unlikely to cause fogging or filming of the photosensitive member.

[0148]

According to the present invention, the toner layer can be uniformly formed on the developing roll, so that the resolution is high. Further, even in a severe environment such as high temperature, high humidity and low temperature, low humidity, fogging and filming of the photoreceptor are prevented. It turns out that it is hard to happen.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a developing roll according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a tandem type color image forming apparatus according to an embodiment of the present invention.

[Description of Signs] 1. Photosensitive Drum 2. Cleaning Device 3. Charging Roll 4. Laser Light Irradiation Device 5. Transfer Roll 7. Developing Roll 8. Layer Thickness Control Blade 9. Supply Roll 10. ..Toner 11..Developing device 13..Heating roll 14..Pressing roll 15..Conveying belt 71..Conductive shaft 72..Rubber elastic

Continued on the front page F term (reference) 2H005 AA06 AA21 AB06 AB07 CB08 CB20 EA10 2H030 AB02 AD01 BB01 BB22 BB41 BB71 2H077 AD06 FA01 FA22

Claims (3)

[Claims] 1. A developing method for developing an electrostatic latent image formed by exposure on a surface of a latent image holding member obtained by being charged by a charging member into a toner image, wherein the surface of a developing roll used for development is developed. Is made of a rubber elastic body, and the circumferential surface roughness of the surface is 10 μm or less and the axial surface roughness of the surface is 10 μm.
m or less, and the boron or phosphorus content of the toner is 0.1
-100 ppm. 2. An image forming method, wherein a toner image obtained by the developing method according to claim 1 is transferred onto a transfer material and then fixed. 3. An operation of developing an electrostatic latent image formed by exposure on a surface of a latent image holding member obtained by being charged by a charging member into a toner image, and then transferring the toner image to a transfer material includes yellow, magenta, cyan, and yellow. This is a color image forming method in which a color toner image is obtained by using each of black toners, and the transferred color toner image is fixed, wherein a surface of a developing roll used in development is made of a rubber elastic body. A color image forming method, wherein the surface has a circumferential surface roughness of 10 μm or less, the surface has an axial surface roughness of 10 μm or less, and the toner has a boron or phosphorus content of 0.1 to 100 ppm.