JP2001013780A - Image forming method and one-component developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent transfer-missing and to obtain a copied image having good image characteristics. SOLUTION: In the image forming method using a one-component developer and a contact transfer process, the thickness of the developer carried on a developer carrier is regulated with a magnetic blade disposed near the developer carrier, a transfer material to which an image is transferred is brought into contact with the surface of an electrostatic latent image support under 10-100 g/cm contact pressure, and an image developed with the developer is transferred to the top of the transfer surface of the transfer material. The one-component developer contains at least a bonding resin and a magnetic powder and has >=105 deg. contact angle to water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for visualizing an electrostatic latent image used in a recording method utilizing an electrophotographic method, an electrostatic recording method, an electrostatic printing method or a toner jet recording method. And an image forming method using the one-component developer.

[0002]

2. Description of the Related Art A conventional image forming method such as electrophotography is disclosed in U.S. Pat.
No. 23910 (U.S. Pat. No. 3,666,363) and Japanese Patent Publication No. 43-24748 (U.S. Pat.
71361) describes various methods. The developing methods applied to these electrophotographic methods are roughly classified into a dry developing method and a wet developing method, and the former can be further classified into a method using a one-component developer and a method using a two-component developer. .

[0003] The specifications of the copying apparatus, such as small size, light weight and low power consumption, have been pursued, and various devices have been devised so as to be constituted by simpler elements.
For this reason, the two-component developing method contradicts demands for downsizing and weight reduction of the machine device, considering that a carrier and an ATR mechanism for controlling the mixing ratio of toner and carrier are required. . From this, it can be said that the one-component developing method is preferable.

[0004] Among the one-component developers, there are many excellent ones using a developer composed of a magnetic toner.
For example, US Pat. No. 3,909,258 proposes a method of developing using a conductive magnetic toner. In this technique, a conductive magnetic toner is supported on a cylindrical conductive sleeve having magnetism therein, and is contacted with an electrostatic charge image to be developed. At this time, in the developing unit, a conductive path is formed by the toner particles between the surface of the recording medium and the surface of the sleeve. Due to the Coulomb force, the toner particles adhere to the image area and are developed.

The developing method using the conductive magnetic toner is an excellent method that avoids the problems associated with the conventional two-component developing method. However, since the toner is conductive, the developed image can be transferred from the recording medium. There is a problem that it is difficult to transfer electrostatically to a final supporting member such as plain paper.

As a developing method using a high-resistance magnetic toner capable of electrostatic transfer, there is a developing method utilizing dielectric polarization of toner particles. However, this method is problematic in that the development speed is essentially low and the density of the developed image cannot be sufficiently obtained, and is practically difficult.

Another development method using a high-resistance magnetic toner is to frictionally charge the toner particles by friction between the toner particles or between the toner particles and a sleeve and the like, and contact the toner particles with an electrostatic image holding member. Methods for developing are known. However, also in this method, since the number of times of contact between the toner particles and the friction member is small, triboelectric charging tends to be insufficient.
Further, this method has a problem that the Coulomb force between the charged toner particles and the sleeve is increased, so that the toner is liable to aggregate on the sleeve, and is practically difficult.

However, Japanese Patent Application Laid-Open No. 55-18656 and the like have proposed a new jumping developing method which has solved the above-mentioned problems. In this method, a magnetic toner is applied very thinly on a sleeve and then frictionally charged, and then the frictionally charged toner is developed very close to an electrostatic image. This method is to apply the magnetic toner on the sleeve very thin, to increase the chance of contact between the sleeve and the toner, to enable sufficient triboelectric charging, and to support the magnetic toner by magnetic force, In addition, by moving the magnet and the toner relatively, the aggregation of the toner particles is released, and the toner is sufficiently rubbed with the sleeve, so that an excellent image can be obtained.

In the above-mentioned jumping developing method, as a method for applying the toner on the sleeve, a conventionally known magnetic blade or a pressing using an elastic blade formed of an elastic material such as rubber is used. There is a method in which the thickness of the magnetic toner layer is regulated and the magnetic toner is applied on the developing sleeve.

However, when an elastic blade is used, since the elastic blade is pressed against the sleeve with a certain pressure, the blade or sleeve surface is liable to wear over a long period of use, and stable triboelectric charging of the toner from start to end is achieved. It can be difficult to do.

On the other hand, with respect to the magnetic toner, a considerable amount of fine powder magnetic powder is mixed and dispersed in the toner, and a part of the magnetic powder is exposed on the surface of the magnetic toner particles.
It is conceivable that the type of the magnetic powder affects the triboelectric charging characteristics and the like of the magnetic toner and consequently the development characteristics of the magnetic toner.

Further, in the conventional jumping developing method using a magnetic toner, when the developing process is repeated for a long period of time, the fluidity of the magnetic toner deteriorates, and normal frictional charging cannot be obtained. Therefore, it tends to be difficult to always keep the thickness of the toner coat layer on the sleeve uniform.

[0013] Magnetic iron oxide is mainly used as the fine magnetic powder contained in the magnetic toner. Although there have been many proposals for this magnetic iron oxide, there are still many points to be improved.

For example, JP-A-3-67265 proposes a method using spherical magnetic particles having a divalent metal oxide in the surface layer of magnetic iron oxide particles. According to this method, in order to weaken the magnetic binding force and magnetic cohesion of the magnetic toner, the holding force of the magnetic particles is preferably 40 to 70 Oe (3.2 to 5.6 kA / m), which is relatively small. It is described that a material having a small residual magnetization is preferable.

However, as a result of a detailed study, it has been found that when spherical magnetic particles are used for the magnetic toner, the magnetic toner particles have a spherical surface, compared to the case where hexahedral or octahedral magnetic particles are used. There is a problem in that the amount of magnetic fine particles exposed to the surface increases, and the amount of shaving on the surface of the electrostatic latent image carrier increases. Further, when spherical magnetic particles are used, the magnetic regulation force of the toner becomes small, so that it becomes difficult to keep the toner coat layer thickness on the sleeve always stable when using a magnetic blade.

On the other hand, in the transfer step, an image forming step includes a step of electrostatically transferring a transferable toner image formed on the surface of the electrostatic latent image carrier to a paper or plastic sheet-like transfer material. In an apparatus, an image carrier that moves endlessly, such as a rotating cylindrical shape or an endless belt shape, is used, and a transfer roller to which a bias is applied is pressed against this, and a transfer material is passed between the two. To transfer the toner image on the electrostatic latent image carrier side onto a transfer material
(For example, an apparatus described in JP-A-59-46664) has been proposed.

[0017] Such an apparatus adjusts the pressing force of the transfer roller against the electrostatic latent image carrier to adjust the static pressure of the transfer material, as compared with a transfer means using corona discharge which has been widely used in the past. The adsorption area on the latent image carrier can be enlarged. In addition, since the above-described apparatus positively supports the transfer material at the transfer portion, the transfer material is less likely to be out of synchronization due to the transfer material transporting unit or to a transfer deviation due to a loop or curl existing in the transfer material. In this type, it is easy to respond to requests for shortening the transfer material transport path and downsizing of the electrostatic latent image carrier as the image forming apparatus of this type is downsized. On the other hand, in a device that performs transfer by contact, a transfer current is supplied from the contact portion, so that it is necessary to apply a certain pressure to the transfer device. When such a pressure (contact pressure) is applied, pressure is also applied to the toner image on the electrostatic latent image carrier, so that toner aggregation is likely to occur.

Further, when the surface of the electrostatic latent image carrier is made of a resin, adhesion between the toner aggregate and the electrostatic latent image carrier occurs, so that the transfer of the toner to the transfer material is prevented. In an extreme case, there is a phenomenon that a portion where the adhesion between the electrostatic latent image carrier and the toner becomes strong is not transferred at all and an image defect occurs on a transferred image.

It has been confirmed by previous studies that this phenomenon is particularly remarkable in a line portion having a thickness of 0.1 to 2 mm. This is because, in the line portion, the amount of applied toner increases due to a so-called edge phenomenon, aggregation tends to occur due to pressure, and loss due to transfer tends to occur. The transferred image at this time is a copy on which only the outline image is formed, and is referred to as “missing during transfer”.

The transfer dropout phenomenon occurs when the transfer material has a thickness of 10
This is particularly likely to occur in thick paper of 0 g / m ² or more, transparency films having high smoothness, and the like. In addition, the tendency is more likely to occur on the back side (second side) of double-sided copying than on single-sided copying. Since a transfer material such as a cardboard or a film is thick, the effect of the transfer electric field is small, and a strong pressurization is considered to easily cause a hollow phenomenon.

On the other hand, since the transfer roller is formed of an elastic material such as rubber, it is worn by a long-term use, the peripheral speed is reduced, and a hollow portion occurs. Also, the transfer roller made of an elastic material is not easy to adjust the balance of the pressing force at the left and right ends unlike the rigid body. For this reason, the transfer speed of the transfer material may be different between the left and right sides, and the transfer direction may be bent. As a result, there is a problem that a one-loop occurs in the transfer material between the transfer portion and the fixing portion to disturb the image. .

In particular, in order to reduce the size of the machine and shorten the first copy time, which are often seen in recent years, the distance between the transfer device and the fixing device is shortened, and the transfer material is sent to the fixing device without passing through a transport system. In such an image forming apparatus,
This problem is more likely to occur. As a result, the transferred image rubs against other objects in the apparatus, causing contamination on the image after fixing, or causing an image distortion due to a shock when the fixing device enters. To prevent this, it is effective to increase the contact pressure of the transfer roller with the electrostatic latent image carrier and increase the holding force at the transfer roller portion. This may cause a phenomenon or cause scratches or scraping on the surface of the electrostatic latent image carrier, resulting in a shorter life of the electrostatic latent image carrier.

It has also been conventionally practiced to reduce the shock by suppressing the occurrence of image distortion by changing the angle at which the transfer material enters the fixing device, but to increase the latitude. It is not enough.
Further, it has been proposed that the transfer speed of the transfer material is controlled to achieve both the transferability and the reduction of the shock caused by the entry of the fixing device. Although this method is certainly effective, it is not only difficult to control but also complicated in the mechanism itself, which is not preferable in terms of cost.

As described above, a transfer apparatus that performs transfer by contact has many advantages such as miniaturization and low power, but tends to have a narrow latitude with respect to a transfer material.

[0025]

As described above, as a problem related to an image forming apparatus and an image forming method using an abutting transfer method, there has been a problem of transfer failure called "missing transfer". . Until now, many approaches from an apparatus side or an approach from a developer have been performed, but a sufficiently satisfactory one has not been devised so far. The cause of this is to reduce the contact pressure at the transfer site in order to prevent the transfer omission phenomenon,
Alternately, changing the peripheral speed of the transfer roller and the electrostatic latent image carrier has conventionally been performed. However, in these cases, adverse effects such as image distortion due to a shock at the time of entry into the fixing device due to deterioration of the paper conveyance and electrostatic damage are caused. This is because phenomena such as shortening of the service life due to scratches and scraping of the latent image carrier occurred. Therefore, in order to obtain a good image, the latitude is extremely narrow.

Accordingly, an object of the present invention is to solve such various problems. That is, an object of the present invention is to provide an image forming apparatus based on pressure transfer such as a contact transfer method, which has a transfer step of obtaining a high-quality image that is faithful to a latent image regardless of the conditions of a transfer material. An object of the present invention is to provide an image forming method and a developer that can be used in this method. In other words, it is an object of the present invention to provide an image forming method and a developer which can obtain a copy image having good image characteristics without any occurrence of the “transfer missing” phenomenon in any image.

Another object of the present invention is to provide an image forming method capable of always providing a high-quality image without causing a transfer omission phenomenon even when a thick transfer material is used or both sides are copied. And a developer.

Another object of the present invention is to provide good transfer of a transfer material, no image distortion at the time of fixing, and
An object of the present invention is to provide an image forming method and a developer which can always obtain good image quality from a thin line to a bold character.

Another object of the present invention is to provide an image forming method and a developer capable of obtaining a copy image having a clear character and a density gradation faithful to a document over a long period of time. It is in.

Another object of the present invention is to provide an image forming method and a developer which are stable against environmental changes such as high temperature and high humidity or low temperature and low humidity and can always exhibit good characteristics. is there.

[0031]

Means for Solving the Problems As a result of intensive studies, the present inventors have focused on the contact angle of the developer, and have used a one-component magnetic developer designed so that this value becomes a certain value or more. As a result, the above-mentioned problem can be solved.

That is, according to the image forming method of the present invention for solving the above-mentioned problems, the electrostatic latent image carried on the electrostatic latent image carrier is formed by a one-component developer carried on the developer carrier. By developing, an image forming method for forming a developed image on the electrostatic latent image carrier, transferring the developed image to a transfer material, and heating and fixing the developed image transferred to the transfer material, The thickness of the developer carried on the developer carrier is regulated by a magnetic blade arranged at a constant distance from the surface of the developer carrier and formed on the electrostatic latent image carrier. The developed image has a transfer surface of the transfer material of 10 to 1000 g / c with respect to the surface of the electrostatic latent image carrier.
By transferring the developed image onto the transfer surface of the transfer material by contacting with a contact pressure of m, the one-component developer contains at least a binder resin and a magnetic powder, and is in contact with water. The angle is at least 105 °.

By using such an image forming method, it is possible to form a good image free from the phenomenon of missing during transfer and to carry the transfer material satisfactorily. Further, according to the image forming method of the present invention, a favorable image can always be formed even in an environment such as high temperature and high humidity or low temperature and low humidity.

When the image forming method of the present invention is used, the transfer material is brought into contact with the surface of the electrostatic latent image carrier,
The transfer may be performed by bringing a biased roller into contact with the back surface of the transfer surface of the transfer material.

The magnetic powder contained in the one-component developer used in the image forming method of the present invention is 79.58.
The saturation magnetization (σs) under a magnetic field of kA / m (1 k Oersted) is 55 Am ² / kg or more, and the residual magnetization (σr)
[Am ² / kg]) and the coercive force (Hc [kA / m]) (σr × Hc) may be 80 to 210 kA ² m / kg. At this time, the magnetic powder may be contained in the one-component developer in a ratio of 20 to 200 parts by weight based on 100 parts by weight of the binder resin. Further, the magnetic powder may have a hexahedral or octahedral shape.

The binder resin contained in the one-component developer used in the image forming method of the present invention may include a polyester resin, a vinyl resin, or a mixture of a polyester resin and a vinyl resin. .

The one-component developer used in the image forming method of the present invention further contains a wax. The wax has a peak molecular weight of 300 to 5000 obtained by gel permeation chromatography, and has a weight average molecular weight of The ratio (Mw / Mn) to the number average molecular weight is 1.1
~ 15. At this time, the wax may have a melting point of 70 to 140 ° C. defined by an endothermic peak temperature at the time of temperature rise measured by a differential scanning calorimeter.

Further, a developer according to the present invention for solving the above-mentioned problems develops an electrostatic latent image carried on an electrostatic latent image carrier with a one-component developer carried on the developer carrier. Thereby forming a developed image on the electrostatic latent image carrier, transferring the developed image to a transfer material, and heating and fixing the developed image transferred to the transfer material, a one-component system used in an image forming method. A developer comprising at least a binder resin and a magnetic powder, and having a contact angle with water of 105 ° or more.

By using such a one-component developer, it is possible to form a good image in which the phenomenon of omission during transfer does not occur. Further, by using the developer of the present invention, even in environments such as high temperature and high humidity or low temperature and low humidity,
A good image can always be formed.

[0040]

Embodiments of the present invention will be described below.

As a result of intensive studies, the inventors have found that in a developing method using a one-component developer, a magnetic blade is used for the developing system, and a developer having a high contact angle is used. It has been found that high transferability can be obtained by the effect. When an elastic blade is used for the development system,
With the wear of the blade and developer carrier due to long-term durability,
The triboelectricity of the developer is reduced. This problem,
In particular, it occurs remarkably when the process speed is high.
However, the image forming method of the present invention uses a magnetic blade and does not directly contact the magnetic blade and the developer carrying member. The agent maintains a stable chargeability all the time. Further, in the image forming method of the present invention,
Since a developer having a high contact angle is used, the developer has high water repellency, and in a high-temperature and high-humidity environment, the tribo is hardly reduced due to the influence of humidity (moisture adhesion to the developer). Become. Therefore, according to the image forming method of the present invention, it is considered that high releasability is achieved even with the developer on the latent image carrier (developer that has contributed to development), and transferability to the transfer material is improved. Can be

First, the one-component developer of the present invention (hereinafter simply referred to as "developer") will be described. The developer of the present invention contains at least a binder resin and a magnetic powder, and has a water contact angle of 105 ° or more.
This contact angle is preferably 105 to 135 °, more preferably 105 to 130 °. When the contact angle of the developer with water is within this range, the developing process is performed when a toner image formed by developing the electrostatic latent image on the surface of the electrostatic latent image carrier with the developer is transferred to a transfer material. Since the releasability of the agent from the electrostatic latent image bearing member is improved, a phenomenon of “missing during transfer” does not occur, and a good copy image can be obtained. If the contact angle is smaller than the above range, the difference between the developer and the contact angle between the developer and the surface of the electrostatic latent image carrier becomes small, so that the electrostatic latent image formed on the surface of the electrostatic latent image carrier is developed. When a toner image formed by development with an agent is transferred to a transfer material, it may be difficult to release the toner image from the surface of the electrostatic latent image carrier. As a result, the above-described transfer dropout phenomenon easily occurs, which is not preferable. Note that this transfer omission phenomenon is likely to appear particularly when a cardboard or a transparency film is used as a transfer material. On the other hand, if the contact angle is larger than the above range, the developing property and the cleaning property of the developer remaining on the electrostatic latent image carrier may be affected, which is not preferable.

According to the study of the present inventor, the developer having the above-mentioned contact angle has a specific acid value because the binder resin constituting the developer has a specific acid value. This can be achieved by including a binder resin and a wax having a specific peak molecular weight and structure.

As the binder resin constituting the developer of the present invention, a resin composition comprising a polyester resin, a vinyl resin, or a mixture of a polyester resin and a vinyl resin can be preferably used. In particular, a resin composition comprising a mixture of a polyester resin and a vinyl resin can be preferably used.

The composition of the polyester resin and the vinyl resin constituting the resin composition is 30: 70-9 by weight.
0:10 is sufficient, but preferably 40:60 to 8
0:20. If the composition ratio of the polyester resin forming the mixed resin composition is too small or too large, the dispersion state of the wax contained in the developer may be difficult to control. Absent. The details of the wax will be described later.

As described above, when the binder resin constituting the developer has a specific acid value, the developer of the present invention can have the above-mentioned contact angle. The acid value of the binder resin is 5 to 60 m in order to control the dispersion state of the wax.
gKOH / g, preferably 7 to 50 mg KO.
More preferably, it has an acid value of H / g. When the acid value is too small or too large, it is difficult to control the dispersion state of the wax in the developer, which is not preferable.

That is, if the polarity of the binder resin and the polarity of the wax described later are made desired, the dispersion state and the dispersion diameter of the wax in the binder resin can be controlled, and the surface of the developer becomes hydrophobic. Lots of high wax, uniform, and
It can be present in a state having a large dispersion diameter.
Thereby, a developer having a high contact angle can be obtained.

In the developer of the present invention, the binder resin preferably contains a THF (tetrahydrofuran) -insoluble component in order to impart high-temperature offset resistance to the developer during fixing to the transfer agent. Further, the melt viscosity of the binder resin is also important for controlling the dispersion of the wax in the kneading step in the production of the developer, so that the content of the THF-insoluble component is also important in this respect. The THF insoluble content is 5 to 60
%, Preferably 7 to 55% by weight, more preferably 10 to 50% by weight. THF
If the content of the insoluble component is too smaller than the above range,
Not only does the high-temperature offset resistance of the developer deteriorate,
Since the melt viscosity in the kneading step becomes too low, reagglomeration of the wax occurs, and it becomes difficult to control the dispersion state.
On the other hand, when the content of the THF-insoluble component is too large than the above range, not only the low-temperature offset property is easily generated, but also a component having a high melt viscosity and a component having a low melt viscosity are mixed in the kneading step, so that the wax Is unfavorable because the dispersion particle size distribution becomes wide and the dispersion state cannot be controlled.

The polyester resin as the binder resin constituting the developer of the present invention generally uses a polycarboxylic acid (generally, dicarboxylic acid) as an acid component and a polyhydric alcohol as an alcohol component, and is obtained by condensation polymerization of these. It is obtained. When used as the developer of the present invention, it is particularly preferable that the components represented by the formulas (a) to (d)
And further contains at least one or more of a divalent carboxylic acid represented by the formula or a monohydric alcohol represented by the formula (e).

[0050]

Embedded image

[0051]

Formula (e) R ₈ —OH wherein R ₁ represents a linear, branched or cyclic alkyl or alkenyl group having 14 or more carbon atoms, and R ₃ , R ₄ ,
R ₅ and R ₆ represent a hydrogen atom, a linear, branched or cyclic alkyl group or alkenyl group having 3 or more carbon atoms, and may be the same substituent, but they are not hydrogen atoms at the same time; R ₈ represents a linear, branched or cyclic alkyl or alkenyl group having 12 or more carbon atoms, and n represents an integer of 12 to 40. Examples of the compound represented by the formula (a) include the following compounds (a-1) to (a-6).

[0052]

Embedded image Examples of the compound represented by the formula (b) include the following compounds (b-1) to (b-4).

[0053]

Embedded image (b-1) HOOC- (CH 2) 14 -COOH (b-2) HOOC- (CH 2) 18 -COOH (b-3) HOOC- (CH 2) 24 -COOH (b-4 ) HOOC— (CH ₂ ) ₃₄ —COOH Examples of the compound represented by the formula (c) include the following compounds (c-1) to (c-3).

[0054]

Embedded image Examples of the compound represented by the formula (d) include the following compounds (d-1) and (d-2).

[0055]

Embedded image Examples of the compound represented by the formula (e) include the following compounds (e-1) to (e-5).

[0056]

Embedded image (e-1) (n) C 12 H 25 -OH (e-2) (i) C 12 H 25 -OH (e-3) (n) C 14 H 29 -OH (e-4 ) (n) when using a _{C 20 H 41 -OH (e-} 5) (n) a polyester resin as C ₃₀ H ₆₁ -OH binder resin of the developer of the present invention, examples of the monomer include the following .

First, the main alcohol components include ethylene glycol, propylene glycol, 1,3-butanediol, 2,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5- ぺPentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl 1,3-
Examples include hexanediol, hydrogenated bisphenol A, bisphenol derivatives represented by the following formula (g), and diols represented by the following formula (h).

[0058]

Embedded image In the above formula (g), R represents an ethylene or propylene group, x and y are each an integer of 1 or more, and x
The average value of + y is 2 to 10.

[0059]

Embedded image The main acidic components include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid or anhydrides thereof; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid or anhydrides thereof; Succinic acid or an anhydride thereof substituted with an alkyl group of the number 6 to 12; and unsaturated dicarboxylic acids such as fumaric acid, maleic acid and citraconic acid, or anhydrides thereof.

As a method of obtaining a vinyl resin as a binder resin constituting the developer of the present invention, a method of polymerizing a monomer constituting the vinyl resin may be mentioned.
The following are examples of monomers used in producing the vinyl resin.

Styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene,
p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, p -Methoxystyrene, p-chlorostyrene, 3,4-dichlorostyrene,
styrene and its derivatives such as m-nitrostyrene, o-nitrostyrene and p-nitrostyrene; ethylene,
Styrene unsaturated monoolefins such as propylene, butylene and isobutylene; unsaturated polyenes such as butadiene and isoprene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl acetate, vinyl propionate And vinyl esters such as vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, methacryl Α-methylene aliphatic monocarboxylic esters such as stearyl acrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, acrylic acrylate Acrylic esters such as pill, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl methyl Vinyl ethers such as ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone Vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide;

Further, unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid and mesaconic acid; maleic anhydride, citraconic anhydride, itaconic anhydride, alkenyl succinic anhydride Unsaturated dibasic acid anhydrides such as those; methyl maleate half ester, maleic acid ethyl half ester, maleic acid butyl half ester, citraconic acid methyl half ester, citraconic acid ethyl half ester, citraconic acid butyl half ester, methyl itaconate Half esters of unsaturated dibasic acids such as half ester, methyl alkenyl succinate half ester, methyl fumarate half ester and methyl half mesaconic acid; unsaturated dibasic acid esters such as dimethyl maleic acid and dimethyl fumaric acid; Le acid, methacrylic acid, crotonic acid,
Α, β-unsaturated acids such as cinnamic acid; crotonic anhydride,
Α, β-unsaturated acid anhydrides such as cinnamic anhydride;
anhydrides of β-unsaturated acids and lower fatty acids; alkenyl malonic acid, alkenyl glutaric acid, alkenyl adipic acid,
Examples thereof include monomers having a carboxyl group such as these acid anhydrides and monoesters thereof.

Further, acrylic acid or methacrylic acid esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate; 4- (1-hydroxy-1-methylbutyl) styrene 4- (1-hydroxy Monomers having a hydroxy group such as -1-methylhexyl) styrene are exemplified.

Examples of the polymerization initiator used for producing a vinyl resin include, for example, 2,2′-azobisisobutyronitrile and 2,2′-azobis (4-methoxy-
2,4-dimethylvaleronitrile), 2,2-azobis (-2,4-dimethylvaleronitrile), 2,2′-azobis (-2methylbutyronitrile), dimethyl-2,
2'-azobisisobutyrate, 1,1-azobis (1
-Cyclohexanecarbonitrile), 2- (carbamoylazo) -isobutyronitrile, 2,2'-azobis
(2,4,4-trimethylpentane), 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile,
Ketone peroxides such as 2,2'-azobis (2-methyl-propane), methyl ethyl ketone peroxide, acetylacetone peroxide, cyclohexanone peroxide, 2,2-bis (t-butylperoxy) butane, t-butylhydro Peroxide, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, di-cumyl peroxide, α, α'-bis (T-butylperoxyisopropyl) benzene, isobutyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5
-Trimethylhexanoyl peroxide, benzoyl peroxide, m-trioil peroxide, di-
Isopropyl peroxydicarbonate, di-2-ethylhexylperoxydicarbonate, di-n-propylperoxydicarbonate, di-2-ethoxyethylperoxycarbonate, di-methoxyisopropylperoxydicarbonate, di (3-methyl -3-methoxybutyl) peroxycarbonate, acetylcyclohexylsulfonyl peroxide, t-butylperoxyacetate, t-butylperoxyisobutyrate,
t-butyl peroxy neodecanoate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxy laurate, t-butyl peroxy benzoate,
t-butyl peroxyisopropyl carbonate, di-
t-butyl peroxyisophthalate, t-butyl peroxyallyl carbonate, t-amyl peroxy 2-
Ethyl hexanoate, di-t-butylperoxyhexahydroterephthalate and di-t-butylperoxyazelate are exemplified.

As described above, as the binder resin contained in the developer of the present invention, each of the above-mentioned polyester resins and each of the vinyl resins can be preferably used, and a mixture of each of these polyester resins and each of the vinyl resins is preferably used. Can be more preferably used.

The developer of the present invention preferably further contains a wax because the contact angle with water has the above value. Wax contained in the developer of the present invention,
The peak molecular weight (Mp) obtained by gel permeation chromatography (for example, using a GPC-150 column manufactured by Waters) is 500 to 5000, and the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) is 1.1 to 1.1. 15, Mp is 700 to 4500, and Mw /
Mn is more preferably 1.2 to 10.

When Mp and Mw / Mn of the wax are in the above ranges, the dispersion particle diameter of the wax is increased,
In addition, since the particle size distribution can be sharpened, the contact angle of the developer can be increased. Therefore, by using a wax having the values of Mp and Mw / Mn in the above ranges in combination with the above-mentioned binder resin, a developer having a contact angle with water of 105 ° or more can be obtained. Mp
Alternatively, when the value of Mw / Mn is smaller than the above range, the dispersed particle diameter of the wax in the developer becomes too small. When the value of Mp or Mw / Mn is larger than the above range, the dispersed particle size can be increased, but it is difficult to make the dispersed particle size uniform since the particle size distribution is widened. . In either case, it is difficult to control the dispersed particle diameter of the wax, and it is difficult to set the contact angle of the developer to a desired value, which is not preferable.

The developer of the present invention may contain two or more different waxes. In this case, Mp obtained by the above gel permeation chromatography method is 500 to 5000, and Mw / Mn is 1 .2 to 15
It is preferable that Mp is 700 to 4500 and Mw is
/ Mn is more preferably 1.5 to 12. Mp
Alternatively, when the value of Mw / Mn is too small or too large, the particle size distribution of the wax in the developer particles becomes too wide, so that it becomes difficult to control the dispersed particle size. Not preferred.

As the wax having the above-mentioned properties in the developer of the present invention, a wax selected from hydrocarbon wax, polyethylene wax or polypropylene wax can be preferably used.

The wax contained in the developer of the present invention is:
Waxes such as synthetic hydrocarbons and the like obtained from the distillation residue of hydrocarbons obtained by the Age method consisting of carbon monoxide and hydrogen or by hydrogenating them can be used. Further, those obtained by separating a hydrocarbon-based wax by use of a press sweating method, a solvent method, vacuum distillation, or a separation crystallization method can be more preferably used.

The wax contained in the developer of the present invention is:
It has a structure represented by the formula (A).

[0072]

Embedded image CH ₃ — (CH ₂ —CH ₂ ) _a —CH ₂ —CH ₂ —X (A) In the formula (A), X represents a hydroxyl group or a carboxyl group. a preferably represents an integer of 20 to 60. More preferably, X is a hydroxyl group and a represents an integer of 30 to 50.

The wax contained in the developer of the present invention is:
In the case of acid-modified polyethylene, 1 to 20 mg KO
It preferably has an acid value of H / g, and is obtained by modifying polyethylene with an acid monomer selected from at least one of maleic acid, half-esterified maleic acid, and maleic anhydride. More preferably, it has an acid value of 3 to 15 mgKOH / g.

In the case where the wax used in the present invention is an acid-modified polypropylene, the polyethylene is made of an acid monomer selected from at least one of maleic acid, a half-ester of maleic acid, and maleic anhydride. It has been denatured. At this time,
The wax preferably has an acid value of 1 to 20 mgKOH / g, and more preferably has an acid value of 2 to 15 mgKOH / g.

The wax contained in the developer of the present invention is:
Differential scanning calorimeter (DS) of wax-containing developer
In the DSC curve measured in C), the melting point defined by the endothermic peak at the time of temperature rise is preferably from 70 to 140 ° C, more preferably from 75 to 135 ° C.
If the melting point of the wax deviates significantly from this range,
This may adversely affect the high-temperature offset resistance and blocking resistance of the developer, which is not preferable.

Next, the magnetic powder contained in the developer of the present invention will be described. As will be described in detail later, the image forming method according to the present invention is applicable to a one-component developing method using a magnetic blade. Therefore, care must be taken in selecting the material of the magnetic powder. In the above developing system, in order to satisfy all items of image density, fog and image quality, the product (σr × Hc) of the residual magnetization (σr) of the magnetic powder and the coercive force (Hc) is 60 to 250 kA ² m. / Kg is preferred.

If the value of σr × Hc is smaller than the above range, the ability of the developer to suppress the flying of the developer at the position between the magnet poles on the developer carrying member is reduced, and fog is generated particularly in a low humidity environment. This is not preferable because it easily occurs. σ
If the value of r × Hc is too small, it will
In the evaluation of a large number of images, there is a problem that it is difficult to keep the layer thickness of the developer on the developer carrier constant, which is not preferable. On the other hand, if the value of σr × Hc is too large, the movement of the developer on the developer carrier is hindered, and the amount of triboelectric charge of the developer is reduced. It is easy to invite and it is not preferable.

Further, in order to increase the solid black image density and satisfy both the density gradation and the character line density, 79.
The saturation magnetization (σs) of the magnetic powder under a magnetic field of 58 (1 k Oe) is preferably 50 kA ² m / kg or more, more preferably 55 kA ² m / kg or more. If the value of σs is smaller than the above range, the amount of the developer that may be present on the developer carrier is reduced, so that the solid black image density is reduced, and the density gradation and the character line density are reduced. It will be difficult to satisfy both.

The shape of the magnetic powder contained in the developer of the present invention is more preferably a hexahedral shape or an octahedral shape. Hexahedral or octahedral magnetic powder makes it more difficult for the magnetic powder to appear on the developer surface as compared to spherical ones. As a result, the number of sites where the binder resin or wax appears on the surface of the developer increases, so that the contact angle of the developer with water can be increased.

Further, as the magnetic powder contained in the developer of the present invention, a magnetic iron oxide such as magnetite, maghematite, ferrite or the like containing a different element and a mixture thereof are more preferably used. At this time, the different elements contained in the magnetic powder are lithium, beryllium, boron, magnesium, aluminum, silicon, phosphorus, germanium, zirconium, tin, sulfur, calcium, scandium, titanium, vanadium, chromium, manganese, and cobalt. , Nickel, copper, zinc and gallium are preferred.

The material of the magnetic powder is most preferably a magnetic iron oxide containing an element selected from the group consisting of magnesium, aluminum, silicon, phosphorus and zinc as a different element. The above-mentioned different element may be taken into the crystal lattice of iron oxide, may be taken into iron oxide as an oxide, or may exist as an oxide or hydroxide on the surface. It is preferable that a large amount of the fine particles exist near the surface of the fine particles of the powder. It is a preferred embodiment that it is contained as an oxide.

These different elements can be incorporated into the particles of the magnetic powder by mixing the salts of the different elements at the time of producing the magnetic powder and adjusting the pH. Further, by adjusting the pH after the formation of the magnetic powder, or by adjusting the pH by adding a salt of each of the different elements, the different elements can be precipitated on the surface of the magnetic particles.

In order to impart good dispersibility and magnetic properties to the developer, the content of the different element is preferably 0.05 to 10% by weight based on the iron element of the magnetic iron oxide. More preferably, it is 0.1 to 7% by weight. If the content of the different element is too low than the above range,
Since the effect of containing different elements cannot be obtained, good dispersibility (in the developer) and magnetic properties cannot be obtained. On the other hand, if the content of the different element is more than the above range, the charge is released too much, resulting in insufficient charging of the developer, making it difficult to obtain good developing characteristics.

The magnetic powder containing a different element can be produced, for example, by the following method.

(A) An aqueous solution containing a ferrous salt as a main component is
Mix with an aqueous solution of an alkali equivalent or more to iron. At this time, the concentration of free hydroxyl groups was maintained at 1 to 3 g / l,
The oxidation reaction is performed at ~ 90 ° C. After the completion of the oxidation reaction, the weight ratio (% by weight) of Zn / Fe in the entire magnetic powder is 0.05.
亜 鉛 3% by weight (preferably 0.1-1.6% by weight) is added with a ferrous salt containing zinc, and the pH is adjusted to 6.0-6.0%.
Adjust to 9.0 and perform the oxidation reaction again. After the oxidation reaction, a ferrous salt containing silicate is added so that the weight ratio (% by weight) of Si / Fe in the whole magnetic fine particles is 0.01 to 3% by weight, and pH 6.0 to 9 is added. And then perform the oxidation reaction again. After completion of the reaction, the mixture is filtered and dried to obtain a magnetic iron oxide as a magnetic powder.

As described above, by adding a different element (in this case, Zn or Si) to the magnetic powder, the electric resistance of the magnetic powder can be reduced without deteriorating the magnetic properties of the magnetic powder, and It is possible to sharpen the charge amount distribution. Therefore, in the developing method using the magnetic blade, the thickness of the developer on the developer carrier can be kept suitable and stable from beginning to end, and as a result, good image characteristics can be obtained.

These magnetic materials have a number average particle size of 0.0
5 to 1.0 μm, preferably 0.1 to 0.5 μm.
More preferably, it is μm. Regarding the BET specific surface area, ^{2 to} 40 m ² / g (more preferably 4 to ²⁰ m ² / g)
g) is preferably used. These magnetic powders
It is preferably used in an amount of 20 to 200 parts by weight based on 100 parts by weight of the binder resin.

A charge controlling agent may be added to the developer of the present invention, if necessary, in order to further stabilize the chargeability. When adding the charge control agent, the amount used is preferably 0.1 to 100 parts by weight of the binder resin.
It is 10 parts by weight, more preferably 0.2 to 5 parts by weight.

The following are used as charge control agents. For example, an organic metal complex or a chelate compound is effective as a negatively chargeable one. Examples thereof include a monoazo metal complex, an aromatic hydroxycarboxylic acid-based metal complex, and an aromatic dicarboxylic acid-based metal complex. aside from that,
Aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids, and their metal salts, anhydrides, esters, and phenol derivatives of bisphenols.

The positively charged ones may be modified with nigrosine and an aliphatic metal salt; tributylbenzylammonium-1-hydroxy-4-naphthosulfonate;
Onium salts such as quaternary ammonium salts such as tetrabutylammonium tetrafluoroborate, and their analogs such as phosphonium salts, and lake pigments thereof (for the lake-forming agent, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, etc.) Acids, ferricyanides,
Metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide; diorganotin borates such as dibutyltin borate, dioctyltin borate, dicyclohexyltin borate;
There are a guanidine compound, an imidazole compound and the like, and these can be used alone or in combination of two or more. Among them, nigrosine, a triphenylmethane compound, and a quaternary ammonium salt compound in which the counter ion is not halogen are preferably used.

Further, any suitable pigment or dye may be added to the developer of the present invention. However, a dark color is preferable so as not to impair the color of the magnetic fine particles.
For example, examples of the pigment include carbon black, aniline black, acetylene black, phthalocyanine blue, and induslen blue. These are used in an amount necessary to maintain the optical density of the fixed image, and the amount added is preferably from 0.1 to 20 parts by weight, and more preferably from 0.2 to 10 parts by weight based on 100 parts by weight of the binder resin. More preferably, the addition amount is in parts by weight. Further, a dye may be further used for the same purpose. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, methine dyes, and the like, and the amount thereof is preferably 0.1 to 20 parts by weight, more preferably 0 to 20 parts by weight, based on 100 parts by weight of the binder resin. .3 to 1
The addition amount of 0 parts by weight is good.

It is preferable that the developer of the present invention further contains an inorganic fine powder or a hydrophobic inorganic fine powder. As these fine powders, for example, silica fine powder or titanium oxide fine powder is preferably used alone or in combination. In particular, in order to impart fluidity to the developer, it is preferable that the fine powder be present near the surface of the developer. The fine powder preferably has a number average particle size of 5 to 100 nm, more preferably 5 to 50 nm. The specific surface area by measuring nitrogen adsorption by the BET method, as a base powder, as long 30 m ² / g or more, preferably in the range of 60~400m ² / g. The fine powder surface-treated as long 20 m ² / g or more, preferably in the range of 40 to 300 m ² / g. The addition amount of these fine powders is 0.03 to 5 parts by weight with respect to 100 parts by weight of the developer in order to obtain an appropriate surface coating amount.
It is preferably in parts by weight.

Among them, the silica fine powder is particularly a dry method produced by vapor phase oxidation of a silicon halide compound, a dry silica called fumed silica, and a so-called wet silica produced from water glass or the like. Both can be used. However, it is preferable to use dry silica which has few silanol groups on the surface and inside and has no production residue.

It is preferable that the silica fine powder has been subjected to a hydrophobic treatment. To hydrophobize, using an organic silicon compound or the like that reacts or physically adsorbs with silica fine powder,
Good to be treated chemically. As a preferable method, after the dry silica fine powder generated by the vapor phase oxidation of the silicon halide compound is treated with a silane coupling agent,
Alternatively, a method of treating with a silane coupling agent and, at the same time, treating with a high molecular weight organic silicon compound such as silicone oil may be used.

Examples of the silane coupling agent used for the hydrophobizing treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, and allylphenyldisilane. Chlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyl Dimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-di Vinyltetramethyldisiloxane,
1,3-diphenyltetramethyldisiloxane is exemplified.

Examples of the high molecular weight organic silicon compound include silicone oil. Preferred silicone oils have a viscosity at 25 ° C. of about 30 to 1000
It belongs to Centistokes. For example, dimethyl silicone oil, methylphenyl silicone oil, α-
Preferred are methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil.

The method of treating the silicone oil may be, for example, a method of directly mixing the silica fine powder treated with the silane coupling agent with the silicone oil using a mixer such as a Henschel mixer, Alternatively, a method of directly spraying silicone oil on silica to be used as a source may be used. Alternatively, after dissolving or dispersing the silicone oil in an appropriate solvent, mixing with a base silica fine powder,
It may be manufactured by removing the solvent.

As a preferable method of hydrophobizing the silica fine powder, for example, a method of adjusting by treating with dimethyldichlorosilane, then with hexamethyldisilazane, and then with silicone oil can be mentioned. As described above, it is particularly preferable to treat the silica fine powder with two or more kinds of silane coupling agents and then perform an oil treatment as a method for effectively increasing the degree of hydrophobicity.

Further, those obtained by subjecting the titanium oxide fine powder to the hydrophobic treatment or oil treatment applied to the silica fine powder described above can also be preferably used in the developer of the present invention.

An external additive other than the silica fine powder may be added to the developer of the present invention, if necessary. For example, it is a fine particle which functions as a charge assisting agent, a conductivity-imparting agent, a fluidity-imparting agent, an anti-caking agent, a releasing agent at the time of hot roll fixing, a lubricant or an abrasive.

Examples of such fine particles include inorganic fine particles and organic fine particles. For example, abrasives such as cerium oxide, silicon carbide and strontium titanate (strontium titanate is preferable); anti-caking agent; carbodiblack, zinc oxide, antimony oxide;
Conductivity imparting agents such as tin oxide; and developability improvers such as white fine particles and black fine particles having a polarity opposite to that of the developer.
The amount of the external additive to be added to the developer is preferably 0.1 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the toner.

Hereinafter, the method for producing the one-component developer of the present invention will be described. First, a binder resin, wax, magnetic powder, and, if necessary, a charge control agent, a pigment or dye as a colorant, and additives are sufficiently mixed by a mixer such as a ball mill. Next, the mixture is melted, kneaded, and kneaded using a hot kneader such as a heating roll, a kneader, or an extruder, so that the resins are compatible with each other, and magnetic fine particles, a charge control agent, A product in which a pigment or a dye is dispersed or dissolved is obtained. After cooling and solidifying this product,
The one-component developer of the present invention can be obtained by pulverization and classification.

The weight average particle size (D4) of the developer of the present invention is preferably 4 to 12 μm in order to have stable developability and to form a good quality image.
When D4 is smaller than the above range, it is difficult to control charging, and it is difficult to maintain stable developing properties from beginning to end. If D4 is larger than the above range, it is not preferable because the quality of the formed image is liable to be deteriorated particularly in long-term evaluation.

Next, an image forming method of the present invention using the above-mentioned developer will be described. The image forming method of the present invention comprises:
The one-component developer containing at least the binder resin and the magnetic powder has a contact angle with water of 105 ° or more, and the contact pressure of the transfer material with the electrostatic latent image carrier is 10 to 10
Except for setting it to 00 g / cm, it can be carried out using an image forming apparatus using a conventional one-component developer. Therefore, the image forming apparatus will be described first, and then the image forming method of the present invention will be described.

As examples of the image forming apparatus used in the present invention, there are an image forming apparatus using a corona charger as shown in FIG. 1, and an image forming apparatus using contact charging as shown in FIG. No. Further, as an example of the transfer unit constituting the image forming apparatus shown in FIGS. 1 and 2, there are a transfer roller shown in FIG. 3 and a transfer belt shown in FIG. Here, a case of an image forming apparatus including a corona charger and a transfer roller will be described as an example, that is, with reference to FIGS. 1 and 3.

The image forming apparatus has a cylindrical electrostatic latent image carrier 1 whose axis is in a direction perpendicular to the plane of FIG. The electrostatic latent image carrier 1 has a photosensitive layer and a conductive substrate, and is rotated in the direction of arrow A in FIG.

Around the electrostatic latent image carrier 1, a primary charger (corona charger) 302 and a primary charger 302 for uniformly charging a part of the surface of the electrostatic latent image carrier 1. Image-modulated laser light 3 applied to the surface of the electrostatic latent image carrier 1 charged by the
05, an exposure unit 30 which projects the laser beam 305 onto a charged surface to attenuate the potential of the projected portion to form an electrostatic latent image
3, a developing device 309 for developing the electrostatic latent image formed by the exposure unit, a conductive transfer roller for transferring the developed image to a transfer material, and a transfer material for transferring the image transferred to the transfer material. And a cleaner 308 for removing residual toner remaining on the surface of the electrostatic latent image carrier 1 even after transfer, and a device for removing static electricity from the electrostatic latent image carrier 1. An erase exposure unit 306 is provided.

The developing device 309 is filled with a developer 310. In the developing device 309, a cylindrical non-magnetic developing sleeve 304, which is a developer carrier, is close to the electrostatic latent image carrier 1 and substantially parallel to the electrostatic latent image carrier 1. And so on. The distance between the electrostatic latent image carrier surface 1 and the developing sleeve 304 is set to be equal to or greater than the thickness of the developer carried on the developing sleeve 304. The developing sleeve 304 is provided in a developing section where the electrostatic latent image is developed, in the same direction as the rotation direction of the electrostatic latent image carrier 1,
That is, it rotates in the direction of arrow B in FIG.

Further, inside the developing sleeve 304, a multi-pole permanent magnet (magnet roll) serving as a magnetic field generating means is provided.
314 is arranged so as not to rotate. further,
In order to regulate the thickness of the developer 310 carried on the developing sleeve 304, an iron magnetic blade 311 is provided at a certain magnetic pole position of the permanent magnet 314 at a certain distance from the surface of the developing sleeve 304. They are arranged to face each other. At this time, the gap between the magnetic blade 311 and the developing sleeve 304 is preferably 50 to 500 μm.

The developer 310 in the developing device 309 is applied on the surface of the developing sleeve 304 and
A negative or positive charge is applied to the developer 310 by friction between the surface of the developer 04 and the developer 310. The thickness of the developer 310 applied on the surface of the developing sleeve 304 is
It is regulated uniformly by the magnetic blade 311. Therefore, the thickness of the developer at the developing site (the surface of the developing sleeve 304 closest to the electrostatic latent image carrier 1) is smaller than the gap between the electrostatic latent image carrier 1 and the developing sleeve 304, so that the developing The agent 310 comes into non-contact with the electrostatic latent image carrier 1. At this time, the thickness of the developer 310 is 30 to 300.
It is preferably in the range of μm.

At this time, in order to improve the developing state, the rotation speed of the developing sleeve 304 is preferably controlled to be 80 to 300% of the speed (process speed) of the surface of the electrostatic latent image carrier 1. If the rotation speed of the developing sleeve 304 is lower than the above range, the amount of the developer contributing to the development is reduced, so that the density tends to decrease. If the rotation speed of the developing sleeve 304 is too high than the above range, an excessive amount of the developer may be developed, which may easily cause adverse effects such as deterioration of fog and an increase in toner scattering amount. Not preferred.

In the developing section, the developer carrier 304
Alternatively, an AC bias or a pulse bias may be applied by the bias applying unit 312. In this case, the AC bias preferably has a frequency f of 200 to 4000 Hz and an amplitude Vpp of 500 to 3000 V. The developer is
The developer particles are transferred to the electrostatic image side by the action of an electrostatic force on the surface of the electrostatic latent image carrier and an AC bias or a pulse bias.

Note that instead of the above-described magnetic blade,
It is also conceivable to use an elastic blade formed of an elastic material such as silicone rubber. However, the elastic blade regulates the layer thickness of the developer by pressing against the surface of the developing sleeve 304 and applies the developer on the developer carrier. That is, since this elastic blade regulates the thickness of the developer by pressing,
When image evaluation is performed for a long period of time, it is difficult to secure a stable developer layer thickness from start to end due to scratches or defects on the elastic blade, or wear on the surface of the developing sleeve 304. In particular, as the image forming apparatus is used for high-speed copying, this tendency becomes more noticeable. For this reason, it is preferable to use a magnetic blade as a means for regulating the thickness of the developer.

The transfer roller 2 has a cylindrical shape having an axis parallel to the electrostatic latent image carrier 1 and its surface is brought into contact with the electrostatic latent image carrier 1 at a predetermined pressure. I have. In the present invention, the contact pressure of the transfer roller 2 against the surface of the electrostatic latent image carrier 1 is set to 10 to obtain a high-quality transfer image.
It is preferably 1000 g / cm and 20 to 800.
g / cm is more preferable. In addition, the fixing device 3
In consideration of the rush shock to 07, it is preferable to apply a contact pressure of 20 g / cm or more. When the contact pressure is lower than the above range, poor transfer tends to occur due to insufficient transfer current. Taking into account the rush shock to the fixing device 307, and when the contact pressure is too large, the occurrence of a transfer omission phenomenon and the occurrence of scratches and scraping on the surface of the electrostatic latent image carrier are reduced. Not preferred to trigger.

In the present invention, the contact pressure (linear pressure) is calculated by the following equation.

[0116]

(Linear pressure) [g / cm] = (total pressure applied to the transfer material) [g] / (length contacted) [cm] Further, the transfer roller 2 is And a conductive elastic layer 2b (see FIG. 3). The conductive elastic layer 2b is made of polyurethane or EPD in which a conductive material such as carbon is dispersed.
M (ethylene / propylene rubber) or the like, and is made of an elastic body having a volume resistance of 10 ⁶ to 10 ¹⁰ Ω · cm. A bias is applied to the metal core 2 a by the constant voltage power supply 3. As the bias condition, the current value is 0.1 to 5
Preferably, the voltage (absolute value) is 0 μA and the voltage (absolute value) is 100 to 5000 V. The voltage (absolute value) is 500 to 400
More preferably, it is 0V.

Next, the image forming method of the present invention will be described with reference to FIG. Here, a case where a negatively charged developer is used as the developer will be described as an example.

First, the surface of the electrostatic latent image carrier 1 is negatively charged by the primary charger 302, and is exposed by a laser beam 305 using an image scanning method. As a result, a digital latent image, which is an electrostatic latent image, is carried on the surface of the electrostatic latent image carrier 1.

This digital latent image is stored in the magnetic blade 31
The reversal development is performed by a one-component developer 310 filled in a developing device 309 provided with a magnet 314 and a developing sleeve 304 as a developer carrier. As described above, the bias applying unit 3 is provided on the developing sleeve 304.
12, an alternating bias, a pulse bias and / or a DC bias are applied.

A bias is applied to the transfer roller 2 by a constant voltage power supply 3. When the transfer material P is transported to the transfer roller 2, the image (toner image) on the surface of the electrostatic latent image carrier 1 developed by the developing device 309 is transferred onto the transfer material P by the transfer roller 2 to which the bias is applied. Is transferred to The transfer material P separated from the electrostatic latent image carrier 1 is subjected to a fixing process by a heating and pressing roller fixing device 307 in order to fix the toner image transferred onto the transfer material P.

The one-component developer remaining on the surface of the electrostatic latent image carrier 1 after the transfer step is removed by a cleaner 308 having a cleaning blade. After the completion of the cleaning process, the electrostatic latent image carrier 1 is neutralized by erase exposure 306, and the process starting from the charging process by the primary charger 302 is repeated.

Here, the image forming method and the image forming apparatus applied to this method when the corona charger is used as the primary charger 302 and the transfer roller 2 is used as the transfer device are described. However, as shown in FIG. 2, a contact charger 415 provided with a bias applying section 416 as a primary charger may be used, or a transfer step may be performed using a transfer belt 6 as shown in FIG. .

Next, the methods for measuring the properties of the developer of the present invention are listed below.

(1) Measurement of contact angle of developer with water (a) Sample preparation: about 10 g of developer was applied at 200 kgf / c
Compression molding is performed for 2 minutes at a pressure of m ² to produce a disk-shaped sample having a diameter of 25 mm and a thickness of about 10 mm. This is about 27
mm glass sample bottle (for example, Snap Cup N
o. 30). Next, on a hot plate heated to 100 to 120 ° C., the sample in the sample bottle was interrogated for about 5 to 10 minutes through a Teflon sheet.
A pressure of kgf / cm ² is applied. When the developer, which is a sample, softens / melts, it is air-cooled to room temperature, and then the glass sample bottle is broken to take out a molten molded product of the developer. This melt-molded product is sequentially polished using an abrasive of # 280 → # 800 → # 1500 to obtain a disk-shaped sample having a diameter of 25 mm and a thickness of about 5 mm. The surface for measuring the contact angle of the disc-shaped sample is finished so as not to be visually scratched.

(B) Measuring method: The contact angle is measured by the following measuring apparatus and measuring conditions. Note that ion-exchanged water or commercially available purified water is used for the measurement. The measurement is performed five times for each sample, and the average value is defined as the contact angle of the developer.

Measuring device: FACE contact angle measuring device (manufactured by Kyowa Interface Chemical Co., Ltd.) Measuring temperature: 23 to 25 ° C. Measuring humidity: 40 to 60 ° C. (2) Magnetic properties (σs, σr, Hc) of magnetic powder A good solvent for the resin is selected, and the developer is dissolved in this solvent. The magnetic powder contained in the solvent is separated using a magnet. By repeating this operation several times, the binder resin that has adhered to the surface of the magnetic powder is washed off and used as a sample.

The magnetic properties are measured by, for example, VSMP-1 manufactured by Toei Industry Co., Ltd. When measuring the magnetic properties, a sample of magnetic powder of 0.1 to 0.15 g was subjected to a sensitivity of 1 mg.
Weigh precisely with a direct reading balance. Measurement of magnetic properties is 25 ° C
Perform in the environment before and after. The external magnetic field when measuring magnetic properties is
The sweep rate is set to 10 minutes when the hysteresis loop is drawn at 79.58 kA / m (1 k Oersted).

(3) Average Particle Size of Magnetic Powder In the case of a developer of magnetic powder, a sample treated in the same manner as in (2) above is used as a sample. A transmission electron micrograph of the magnetic powder is projected and, after magnifying 40,000 times, arbitrarily select 250 developer particles, and then select Mar particles in the projected diameter.
The tin diameter (the length of a line segment bisecting the projected area in a certain direction) is measured, and this is indicated by the number average diameter.

(4) Measurement of acid value The acid value is measured according to the measurement method described in JIS K0070. Measurement device: Automatic potentiometric titrator AT-400 (manufactured by Kyoto Electronics) Calibration of the device: 120 ml of toluene and 30 ml of ethanol
Is used. Measurement temperature: 25 ° C. Sample preparation: 1.0 g of toner is added to 120 ml of toluene, and dissolved by stirring with a magnetic stirrer at room temperature (about 25 ° C.) for about 10 hours. 30 ml of ethanol
To make a sample solution.

Measurement operation: 1) The sample is used after removing additives other than the binder resin in advance, or the acid value and the content of components other than the binder resin and the crosslinked binder resin are determined in advance. . 0.8 to 2.0 (g) of the crushed sample is precisely weighed. The weight of the precisely weighed binder resin is defined as W (g). For example, when measuring the acid value of the binder resin from the developer, the acid value and the content of the pigment, the dye, the magnetic powder or the like are separately measured, and the acid value of the binder resin is obtained by calculation. 2) A sample (binder resin) was placed in a 300 (ml) beaker, and a mixed solution of toluene / ethanol (4/1) 150
(Ml) and dissolve. 3) Titration with an ethanol solution of 0.1 mol / l KOH using an automatic potentiometric titrator (for example, a potentiometric titrator AT-400 manufactured by Kyoto Electronics Co., Ltd. (wi)
n workstation) and automatic titration using an ABP-410 motorized burette is available). 4) The amount of the KOH solution used at this time is defined as S (ml), a blank is measured at the same time, and the amount of the KOH solution used at this time is defined as B (ml). 5) Calculate the acid value by the following equation. f is a factor of KOH.

[0131]

## EQU2 ## Acid value (mgKOH / g) = ｛(S−B) × f ×
5.61｝ / W (5) Measurement of THF-insoluble content 0.5 to 1.0 g of the developer is weighed (this is referred to as W ₁ g), and this is filtered with a cylindrical filter paper (for example, No. 86 manufactured by Toyo Roshi Kaisha, Ltd.).
R) and run through a Soxhlet extractor, where T
Extract with 200 ml of HF for 10 hours. After evaporating the soluble component solution extracted by the solvent, 10
After vacuum drying for several hours at 0 ° C., the amount of the THF-soluble resin component is weighed (this is referred to as W ₂ g). Next, the weight (W ₃ g) other than the resin component in the toner. The THF-insoluble content is obtained from the following equation.

[0132]

(Equation 3) Alternatively, the extracted component (W ₄ g) may be weighed, and the THF-insoluble content may be determined from the following equation.

[0133]

(Equation 4) (6) Measurement of melting point of wax ASTM D3418- using a differential scanning calorimeter (DSC measuring device) and DSC-7 (manufactured by PerkinElmer).
Measure according to 82.

The measurement sample is 2 to 10 mg, preferably 5 m
Weigh g precisely. This was put in an aluminum pan, and an empty aluminum pan was used as a reference.
The measurement is carried out at a temperature rising rate of 10 ° C./min under a normal temperature and a normal humidity in a range of 200 ° C. to 200 ° C.

In this heating process, an endothermic peak of the main peak of the DSC curve in the temperature range of 30 to 200 ° C. is obtained. The temperature of the endothermic main peak is defined as the melting point of the wax.

(7) Measurement of glass transition temperature (Tg) of binder resin ASTM D3418- was measured using a differential scanning calorimeter (DSC measuring device) and DSC-7 (manufactured by PerkinElmer).
Measure according to 82.

The measurement sample is 5 to 20 mg, preferably 10
Weigh the mg precisely. This was placed in an aluminum pan, and an empty aluminum pan was used as a reference.
The measurement is performed in a temperature range of 0 to 200 ° C. at a temperature increasing rate of 10 ° C./min under normal temperature and normal humidity. In this heating process, the temperature is 40 to 10
An endothermic peak of the main peak in the range of 0 ° C. is obtained.

At this time, the intersection between the line of the midpoint of the baseline before and after the endothermic peak appears and the differential heat curve is defined as the glass transition temperature Tg in the present invention.

(8) Measurement of molecular weight distribution of wax GPC measuring apparatus: GPC-150C (Waters) Column: GMH-HT 30 cm double (manufactured by Tosoh Corporation) Temperature: 135 ° C. Solvent: o-dichlorobenzene (0.1% ionol) Addition) Flow rate: 1.0 ml / min Sample: Inject 0.4 ml of 0.15% sample Under the above conditions, the molecular weight of the sample is calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample. It is calculated by converting to a polyethylene using a conversion formula derived from the Mark-Houwink viscosity formula.

(9) Measurement of molecular weight distribution of binder resin The molecular weight of the chromatogram by GPC is measured under the following conditions.

The column was stabilized in a heat chamber at 40 ° C., and tetrahydrofuran (THF) was passed through the column at this temperature as a solvent at a flow rate of 1 ml per minute.
As the binder resin, a resin passed through a roll mill (130 ° C., 15 minutes) is used as a sample. A THF solution of the resin adjusted to a concentration of 0.5 to 0.6% by weight was added to the column for 50 to 20.
Measure by injecting 0 μl. The molecular weight distribution of the sample is
It is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number. As a standard polystyrene sample for preparing a calibration curve, for example, P
less Chemical Co. Made or
Tosoh Corporation with a molecular weight of 6 × 10 ² , 2.1 × 10 ³ , 4
× 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 ×
10 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ ,
It is appropriate to use 4.48 × 10 ⁶ samples and to use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

In order to accurately measure the molecular weight region of 10 ³ to 2 × 10 ^6, a plurality of commercially available polystyrene gel columns are preferably combined.
rs Co., Ltd. μ-styragel 500, 10 ³ , 1
0 ⁴ 10 ⁵ combination or, shodex of Showa Denko Co., Ltd.
KA-801, 802, 803, 804, 805, 8
06,807 are preferred.

(10) Measurement of Particle Size Distribution of Developer The particle size distribution of the developer of the present invention is measured by using Coulter Counter TA-II or Coulter Multisizer II.
(Manufactured by Coulter). As the electrolytic solution, a solution prepared by preparing a 1% aqueous NaCl solution using primary sodium chloride is used. For example, ISOTON-II (manufactured by Coulter Scientific Japan) can be used. At the time of measurement, 0.1 to 5 ml of a surfactant, preferably an alkylbenzenesulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution.
Add ~ 20 mg. The electrolyte in which the developer of the sample is suspended is
Perform a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and measure the volume and number of the developer having a particle size of 2 μm or more by using the above-described measuring device, using a 100 μm aperture as an aperture, to obtain a volume distribution and a number distribution. Was calculated.

[0144]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

<Production Example 1 of Binder Resin> Terephthalic acid 4.0 mol% Succinic acid derivative represented by formula (a-3) 3.5 mol% Trimellitic anhydride 3.0 mol% Bisphenol A propylene oxide addition Product 7.5 mol% Bisphenol A ethylene oxide adduct 3.5 mol% The above polyester monomer is put into an autoclave together with an esterification catalyst, and a decompression device, a water separation device, a nitrogen gas introduction device, a temperature measurement device and a stirring device are provided. The reaction mixture was mounted and subjected to a polycondensation reaction while heating to 210 ° C. in a nitrogen gas atmosphere to obtain a polyester resin.

Next, 75 parts by weight of the above polyester resin, 15 parts by weight of styrene, 10 parts by weight of 2-ethylhexyl acrylate and 2 parts by weight of dibutyltin oxide were added to 100 parts by weight of xylene, and the mixture was heated to the reflux temperature of xylene. Further, under a nitrogen atmosphere, a solution prepared by dissolving 1 part by weight of t-butyl hydroperoxide in 20 parts by weight of xylene was added dropwise over 1 hour. After keeping at that temperature for further 8 hours, the mixture was heated to 200 ° C. under reduced pressure and the solvent was removed to obtain a resin composition (1) composed of a mixture of a polyester resin and a vinyl resin.

The obtained resin had an acid value of 19 and a Tg of 59.
It was 5 ° C., had a peak at 8000 in the GPC chart, and had a gel fraction of 26%.

<Production Examples 2 to 6 of Binder Resin> A polyester resin and a polyester resin were prepared in the same manner as in Production Example 1 of the resin except that the wax shown in Table 1 was added in the production process of the resin of the resin composition (1). Resin composition consisting of a mixture with vinyl resin (2)
To (6) were obtained.

[0149]

[Table 1] <Production Example 7 of Binder Resin> 75 parts by weight of styrene 12 parts by weight of n-butyl acrylate 10 parts by weight of monobutyl maleate 2 parts by weight of di-tert-butyl peroxide In 200 parts by weight of xylene heated to the reflux temperature, The above material was added dropwise over 5 hours. After completion of the polymerization under xylene reflux (about 140 ° C.),
Xylene was removed while raising the temperature to ° C. The resin thus obtained is referred to as resin A.

Resin A 30 parts by weight Styrene 47 parts by weight N-butyl acrylate 13 parts by weight Monobutyl maleate 8 parts by weight Divinylbenzene 0.5 parts by weight Benzoyl peroxide 1.5 parts by weight Wax (4) 4 parts by weight Part 7 parts by weight of wax (6) Next, 180 parts by weight of water in which 0.1 part by weight of a partially saponified polyvinyl alcohol was dissolved was added to the above-mentioned material, followed by stirring to obtain a suspension dispersion. 50 parts by weight of water was further added thereto, and the above suspension and dispersion was added to a reaction vessel purged with nitrogen.
The suspension polymerization reaction was performed at a reaction temperature of 80 ° C. for 10 hours. After the reaction, the resin composition was washed with water, dehydrated and dried to obtain a resin composition (7) which was a vinyl resin containing wax.

The obtained vinyl resin (7) had an acid value of 28,
At Tg of 58 ° C, the GPC chart shows 5000 and 160
It had a peak at 00 and the gel fraction was 28%.

<Comparative Production Example 1 of Binder Resin> Terephthalic acid 8.5 mol% Trimellitic anhydride 3.5 mol% Bisphenol A propylene oxide adduct 5.0 mol% Bisphenol A ethylene oxide adduct 5.0 mol % Charge the above materials together with an esterification catalyst into an autoclave, equip it with a decompression device, a water separation device, a nitrogen gas introduction device, a temperature measurement device and a stirrer, and heat it to 200 ° C in a nitrogen gas atmosphere while performing condensation polymerization. The reaction was performed to obtain a polyester resin (comparative resin composition (1)).

The acid value of the obtained resin is 12, and the Tg is 60 ° C.
Has a peak at 5000 in the GPC chart,
The gel fraction was 5%.

<Comparative Production Example 2 of Binder Resin> 18 parts by weight of styrene 5 parts by weight of 2-ethylhexyl acrylate The above materials were added to 100 parts by weight of xylene, and heated to the reflux temperature of xylene under a nitrogen atmosphere. Next, a xylene solution in which 1 part by weight of t-butyl peroxide was dissolved was added dropwise to 50 parts by weight of xylene over about 1 hour.
By heating for a period of time, a radical polymerization reaction was performed.
After completion of the polymerization reaction, 80 parts by weight of the above-mentioned comparative resin composition (1) (polyester resin) was added to the xylene solution in which the vinyl polymer was dissolved, and dissolved and mixed. Xylene was removed under reduced pressure to obtain a mixture of a polyester resin and a vinyl polymer (comparative resin composition (2).

The acid value of the obtained resin is 5, and Tg is 60 ° C.
In the GPC chart, peaks were found at 2800 and 7000, and the gel content was 7%.

<Production Example 1 of Magnetic Powder> Fe ²⁺ 1.5 mol /
1.65 liters of aqueous ferrous sulfate solution containing 1 liter;
Mix 88 liters of 4N sodium hydroxide aqueous solution,
Stir well.

After adjusting the residual sodium hydroxide in the mixed aqueous solution to 4.2 g / liter, the temperature was adjusted to 80 ° C.
, Air was blown at a rate of 30 liters / minute to once terminate the reaction. The reaction product thus obtained is referred to as “reaction slurry A”.

Next, 2.25 liters of an aqueous solution obtained by adding zinc sulfate so that Zn ²⁺ becomes 0.5 moles / liter was separately added to an aqueous ferrous sulfate solution containing 1.0 moles / liter of Fe ^2+. Prepare and add to the reaction slurry A,
The reaction was terminated by blowing air at a rate of 5 l / min. The reaction product thus obtained is referred to as “reaction slurry B”
And

Next, an aqueous solution of ferrous sulfate containing 1.0 mol / l of Fe ²⁺ , to which sodium silicate (No. 3) was added so that the content of Si ⁴⁺ was 0.45 mol / l. .3 L was separately prepared, added to the reaction slurry B, and air was blown at 15 L / min again to terminate the reaction.

The obtained magnetic powder (1) was processed by the usual washing, filtering, drying and crushing steps. This magnetic powder
Table 2 shows the magnetic properties of (1).

<Production Example 2 of Magnetic Powder> A magnetic powder (2) was obtained in the same manner as in Production Example 1 of magnetic powder except that the amount of zinc sulfate and the reaction conditions were changed. Table 2 shows the magnetic properties of the magnetic powder (2).

<Production Example 3 of Magnetic Powder> Production Example 1 of magnetic powder except that zinc sulfate and sodium silicate were not added.
Magnetic powder (3) was obtained in the same manner as described above. Table 2 shows the magnetic properties of the magnetic powder (3).

<Production Example 4 of Magnetic Powder> The magnetic powder (4) having the magnetic properties shown in Table 2 by changing the amounts and methods of addition of zinc sulfate and sodium silicate, the pH of the reaction system, the reaction time, and the reaction temperature. I got

[0164]

[Table 2] <Example 1> Resin composition (1) 100 parts by weight Magnetic fine particles (1) 90 parts by weight Monoazo-based iron complex represented by the following formula 2 parts by weight Wax (1) 8 parts by weight

[0165]

Embedded image After pre-mixing the above mixture with a Henschel mixer,
Melt kneading was performed at 130 ° C. using a twin-screw kneading extruder. After allowing the kneaded product to cool, it is coarsely pulverized by a cutter mill, further pulverized by a fine pulverizer using a jet stream, and further classified by an air classifier to obtain a fine powder having a weight average particle size of 7.0 μm. I got a body.

Next, silica fine powder (BET specific surface area 30
0 m ² / g) 100 parts by weight of dimethyldichlorosilane 2
After the treatment with 0 parts by weight, the treatment was further carried out with 10 parts by weight of hexamethyldisilazane. Further, dimethyl silicone oil (oil viscosity 10
0CS) After spraying 15 parts by weight on the silica fine powder using a spray and applying the mixture, the mixture is heated at 190 ° C. for 5 hours,
A treated silica fine powder having a degree of hydrophobicity of 98.0% and a BET specific surface area of 200 m ² / g was obtained.

To 100 parts by weight of the kneaded material fine powder, 1.2 parts by weight of the treated silica fine powder and 3.0 parts by weight of strontium titanate fine particles were added and mixed with a Henschel mixer to obtain a one-component developing solution. Agent (1) was obtained.

The image evaluation when an image was formed using the one-component developer (1) was evaluated using a Canon copier GP-4.
0 (see FIG. 2). Here, the process speed (the rotation speed of the electrostatic latent image carrier 1) was set to 150 mm / s. Developer carrier (developing sleeve 3
The peripheral speed of 04) was 1.8 times the process speed.

The electrostatic latent image carrier 1 was charged by contact charging using a charging roller having a conductive rubber layer made of EPDM and the surface of which was coated with a nylon resin.

The electrostatic latent image carrier 1 has a diameter of 3 mm.
A photosensitive drum having an OPC photosensitive layer on a 0 mm aluminum cylinder was used as a developer carrying member.
mm aluminum substrate, subjected to blasting, and provided with a resin layer in which conductive fine powder is dispersed,
Fixed magnet 3 having four magnetic poles (the developing magnetic pole is 950 G)
14 was used.

The conditions for the transfer roller 2 were set as follows. The rubber hardness of the transfer roller 2 was 33 °. The bias application conditions were as follows. When the transfer material P was A4 size paper, the constant current was 20 μA, and when the transfer material P was postcard size paper, the constant voltage was +2 kV. Transfer roller 2
The conductive elastic layer 2b is made of EPD in which conductive carbon is dispersed.
M, and its volume resistance is 10 ⁸ Ω · cm. The contact pressure of the transfer material P against the electrostatic latent image carrier 1 was set to 100 g / cm.

The gap between the developer carrier 1 and the magnetic blade 311 is set to 210 μm, the gap between the developing sleeve 304 and the electrostatic latent image carrier 1 is set to 200 μm, and an AC bias (f = 2000 Hz, Vpp = 900 V) And a DC bias (Vdc = −550 V) was applied to the developing sleeve 304. The potential of the dark portion on the electrostatic latent image carrier 1 is-
The voltage was set to 720 V, the light potential was set to -160 V, and the development was performed by reversal development.

The image was evaluated in a normal temperature and low humidity environment (23 ° C./5
% RH), using a chart with a document ratio of 6%, 64
Continuous copying of 60,000 sheets was performed with g / m ² A4 size paper. Further, before and after this evaluation (at the start and after copying 60,000 sheets), double-sided copying was performed using a postcard made by government, and the level of missing during transfer was confirmed. Table 4 shows the results. Next, the above experiment was conducted under a high temperature and high humidity environment (32 ° C./85% R).
H) was also performed. Table 5 shows the results.

The evaluation method is described below. (1) The evaluation was performed in five grades of （(good), △ (somewhat good), △ (normal: acceptable level), △ (somewhat bad), and × (bad). (2) Two-sided copying was performed using a postcard made by government as a transfer material, and the image was observed by a microscope (magnification: 50 times) to determine the omission in the transfer. (3) The shock at the time of entry into the fixing device was evaluated by making a copy using a line original and visually checking the blur of the line on the image. (4) The image quality was comprehensively determined by visually observing the copied image. (5) The image density is a value obtained by measuring the reflection image density with Macbeth RD918 (Macbeth). (6) Regarding the surface condition of the drum, the surface layer thickness of the electrostatic latent image carrier is measured by the quiescent current, and the scratch mark appearing on the copy image is matched with the scratch on the surface of the electrostatic latent image carrier. Judgment was made comprehensively by combining the above items.

In this example, good developability was obtained in both normal temperature, low humidity, and high temperature and high humidity environments. Was confirmed.

Examples 2 to 8 The same procedures as in Example 1 were carried out except that the binder resin and the magnetic powder used in the production of the one-component developer were changed as shown in Table 3. A developer was manufactured by the method, and image evaluation was performed using the developer. However, in Examples 7 and 8, the contact pressure of the transfer material on the electrostatic latent image carrier was 300 g / cm.
And 700 g / cm. Tables 4 and 5 show the evaluation results. Under any environment, good results were obtained as in the case of Example 1.

[0177]

[Table 3] <Embodiment 9> In Embodiment 1, the process speed (peripheral speed of the electrostatic latent image carrier) was changed from 150 mm / s to 210 mm.
Except for changing to / s, the same image evaluation as in Example 1 was performed. As shown in Tables 4 and 5, the results are shown in Example 1.
There was no significant difference, and good results could be obtained.

<Embodiment 10> In Embodiment 1, the process speed (peripheral speed of the electrostatic latent image carrier) was changed to 150 mm / s.
The image evaluation was performed in the same manner as in Example 1 except that the image evaluation was changed to 100 mm / s. As shown in Tables 4 and 5, there was no significant difference from Example 1 and good results could be obtained.

<Embodiment 11> The embodiment 1 is the same as the embodiment 1 except that the transfer roller 2 is changed to a transfer belt 6 having a conductive roller 7 (see FIG. 4) to which a bias is applied.
Image evaluation was performed in the same manner as described above. As shown in Tables 4 and 5, there was no significant difference from Example 1 and good results could be obtained.

<Comparative Examples 1 and 2> In Example 1,
A developer was produced in the same manner as in Example 1 except that the binder resin used in producing the developer was changed to Comparative Resin Compositions (1) and (2), respectively, and an image was formed using this developer. An evaluation was performed. The results are shown in Tables 4 and 5. In each case, although no major defect was observed in terms of developability (image quality of line image, fogging, etc.), the level of missing during transfer was inferior to each of the above Examples. In particular, in the evaluation using the postcard manufactured by 60,000 copies, the level of the omission during the transfer was remarkably reduced.

Comparative Example 3 Image evaluation was performed in the same manner as in Example 1 except that the contact pressure of the transfer material with the electrostatic latent image carrier was changed to 5 g / cm. . The results are shown in Tables 4 and 5. As shown in Tables 4 and 5, under both normal temperature and low humidity and high temperature and high humidity environments, the image quality was deteriorated due to the occurrence of omission during transfer, and the image distortion due to the shock when the transfer material entered the fixing device. The occurrence of such adverse effects was observed.

<Comparative Example 4> Image evaluation was performed in the same manner as in Example 1, except that the contact pressure of the transfer material with the electrostatic latent image carrier was changed to 1500 g / cm. . The results are shown in Tables 4 and 5. From the start, the post-transfer dropout level of the postcard was poor, and the image density decreased as the number of copies increased. After the evaluation of 60,000 sheets, the surface of the electrostatic latent image carrier was observed. As a result, many scratches were found on the surface, and it was confirmed that the amount of shaving of the surface layer was increased.

<Comparative Example 5> In Example 1, the magnetic blade for regulating the thickness of the developer layer of the developer carrier was changed to an elastic blade made of silicone rubber, and was brought into contact with the developing sleeve. Thickness regulated. Otherwise, image evaluation was performed in the same manner as in Example 1. As shown in Tables 4 and 5, although there was no problem at the start, the image density and the image quality became remarkably reduced as the number of copies increased. After the evaluation of 60,000 copies, the elastic blade was observed. As a result, many defects at the blade tip were found.

<Reference Example 1> Production of a developer and image evaluation were performed in the same manner as in Example 1, except that the magnetic powder used in the production of the developer was changed to magnetic powder (3). did. The results are shown in Tables 4 and 5. In this case, there was no problem with respect to the transferability of the developer at the start, but with regard to the developability, only an image in which fogging was particularly noticeable was obtained, and both image density and image quality were not satisfactory.

<Reference Example 2> In Example 1, except that the magnetic powder used in the production of the developer was changed to the magnetic powder (4),
Production of a developer and image evaluation were performed in the same manner as in Example 1. The results are shown in Tables 4 and 5. Regarding developability,
As in Reference Example 1, only an image with noticeable fog was obtained. The transferability was also inferior to each of the above examples. Further, the surface of the electrostatic latent image carrier after copying 60,000 sheets had a large amount of scratches and shavings.

[0186]

[Table 4]

[0187]

[Table 5]

[0188]

As described above, by using the developer of the present invention containing at least a binder resin and a magnetic component and having a contact angle to water of 105 ° or more and an image forming method using this developer, In particular, good image characteristics excellent in transferability can be obtained.

Further, according to the present invention, in an image forming method using a contact transfer method such as pressure transfer, a high-quality image faithful to a latent image can be obtained regardless of transfer material conditions. Can be

Further, according to the present invention, a transferred image having good image characteristics can be obtained without occurrence of the “transfer missing” phenomenon in any image. Further, even when a thick transfer material is used, or when copying is performed on both sides, the phenomenon of “missing during transfer” does not occur, and a high-quality image can always be obtained.

Further, according to the present invention, the transfer material is conveyed well, and no image distortion occurs during fixing.
Good image quality can always be obtained from thin lines to bold characters.

Further, according to the present invention, it is possible to obtain an image in which characters are clear and have a density gradation property faithful to an original document for a long period of time.

According to the present invention, furthermore, it is stable against environmental changes such as high-temperature, high-humidity or low-temperature, low-humidity environment and can always exhibit good characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an image forming apparatus using a corona charger as a primary charger for carrying out an image forming method of the present invention.

FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus that performs charging by contact charging to carry out the image forming method of the present invention.

FIG. 3 is a contact transfer device using a transfer roller, which is applied to the image forming apparatus of FIGS. 1 and 2;

4 is a contact transfer device using a transfer belt, which is applied to the image forming apparatuses of FIGS. 1 and 2;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrostatic latent image carrier 2 transfer roller (roller transfer means) 2 a core 2 b conductive elastic layer 3 constant voltage power supply 4, 5 transfer / conveyance guide 6 transfer belt 7 conductive roller 302 primary charger 304 developing sleeve (developer) Carrier) 305 Pre-exposure 306 Erase exposure device 307 Fixing device 308 Cleaner 309 Developing device 310 One-component developer 311 Magnetic blade 312 Developing bias applying section 313 Developer stirring and conveying section 314 Fixed magnet 415 Contact charging section 416 Bias applying section P transfer Lumber

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H005 AA01 AA02 AA06 CA04 CA08 CA13 CA14 CB03 EA02 EA03 EA06 EA07 EA10 FA06 2H032 AA05 BA12 BA23 CA02 DA04 DA11 DA13 2H077 AD02 AD06 AD13 AD23 AD24 AD36 AD37 AE03 AE04 AE03 AE04

Claims (9)

[Claims] An electrostatic latent image carried on an electrostatic latent image carrier is developed with a one-component developer carried on a developer carrier to thereby develop a developed image. Forming an image on the transfer material, transferring the developed image to a transfer material, and heating and fixing the developed image transferred to the transfer material, wherein the thickness of the developer carried on the developer carrier is The developed image formed on the electrostatic latent image carrier is regulated by a magnetic blade disposed at a predetermined distance from the surface of the developer carrier, and the transfer surface of the transfer material is fixed on the electrostatic latent image carrier. 10 to the surface of the latent image carrier
By contacting at a contact pressure of 1000 g / cm,
The developed image is transferred onto a transfer surface of the transfer material, wherein the one-component developer contains at least a binder resin and a magnetic powder, and has a contact angle to water of 105 ° or more. Image forming method. 2. The method according to claim 1, wherein the transfer material is brought into contact with the surface of the electrostatic latent image carrier by bringing a biased roller into contact with the back surface of the transfer surface of the transfer material. The image forming method according to claim 1, wherein 3. The magnetic powder according to claim 1, wherein the magnetic powder has a 79.58 kA / m (1
k Oersted) magnetic field (σs) of 5
5 Am ² / kg or more and the residual magnetization (σr [Am ² / k
g]) and the coercive force (Hc [kA / m]) (σr × H
3. The image forming method according to claim 1, wherein c) is 80 to 210 kA ² m / kg. 4. The one-component developer according to claim 1, wherein the magnetic powder is contained in the one-component developer in a ratio of 20 to 200 parts by weight based on 100 parts by weight of the binder resin. Item. 5. The image forming method according to claim 1, wherein the magnetic powder has a hexahedral or octahedral shape. 6. The binder resin according to claim 1, wherein the binder resin contains a polyester resin, a vinyl resin, or a mixture of a polyester resin and a vinyl resin.
The image forming method according to any one of the above. 7. The one-component developer further contains a wax, wherein the wax has a peak molecular weight obtained by gel permeation chromatography of 300 to 5000, and a ratio (Mw) between the weight average molecular weight and the number average molecular weight. /
Mn) is 1.1 to 15;
7. The image forming method according to any one of claims 1 to 6. 8. The wax has a melting point defined by an endothermic peak temperature upon heating measured by a differential scanning calorimeter of 70 to 70.
The image forming method according to claim 7, wherein the temperature is 140C. 9. The electrostatic latent image carrier is developed by developing an electrostatic latent image carried on the electrostatic latent image carrier with a one-component developer carried on a developer carrier. A one-component developer used for an image forming method which is formed on, transfers the developed image to a transfer material, and heat-fixes the developed image transferred to the transfer material, comprising at least a binder resin and a magnetic powder. And a contact angle with water of 105 ° or more.