JP3507313B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus used in an electrophotographic method, an electrostatic recording method, a magnetic recording method, etc., and particularly, an image forming method in which a toner image on a latent image carrier is transferred by a contact transfer means. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic method, U.S. Pat. No. 2,297,691 and JP-B-42-23910 are known.
A number of methods are known as described in Japanese Patent Publication No. 43-24748 and Japanese Patent Publication No. 43-24748. Generally, a photoconductive substance is used to form an electrostatic latent image on a photoreceptor by various means, and then the latent image is developed with toner,
If necessary, the toner image is transferred to a transfer material such as paper and then fixed by heating, pressure, heating and pressurizing or solvent vapor to obtain a copy.

In an image forming apparatus such as a general copying machine, a transfer device for transferring a toner image on a latent image carrier to a transfer material is supplied with a high voltage on a discharge wire facing the latent image carrier. A transfer device that applies so-called corona discharge has been widely used. However, since the corona discharger is basically based on air discharge, it often generates ozone, which is not desirable for the human body. Therefore, it is necessary to add a special mechanism to remove ozone, which makes the device larger. Was to be complicated.

Therefore, in recent years, instead of such a corona discharger, a contact type transfer device which generates less ozone has been studied and has been put into practical use. Such an apparatus has an advantage that the transfer can be performed by applying a low voltage and the amount of ozone generated can be reduced as compared with the transfer means using the corona discharge which has been widely put into practical use.
Furthermore, by adjusting the pressure contact force of the transfer roller with respect to the latent image carrier, it is possible to enlarge the adsorption area of the transfer material with respect to the latent image carrier. Further, since the transfer material is positively pressed and supported at the transfer portion, there is little risk of synchronization failure due to the transfer material transporting means and transfer deviation due to loops and curls existing in the transfer material, and transfer due to downsizing of the image forming apparatus. It is easy to meet the demand for shortening the material conveying path and downsizing the latent image carrier.

However, since the back surface charge is less supplied than in the case of corona transfer, when peeling discharge occurs during the separation of the transfer material from the latent image carrier, it is transferred onto the transfer material. There is a problem in that the toner holding power is lowered, the toner is scattered, and the dot reproducibility is lowered.
In the case of the reversal developing system, the charge polarity of the toner on the transfer material becomes equal to the charge polarity of the surface of the latent image carrier. Therefore, the transfer current supplied from the transfer rotator easily flows into the surface of the latent image carrier. As a result, the transfer charges cannot be sufficiently retained on the transfer material, and transfer defects are likely to occur. In order to prevent this,
It was confirmed that when a large amount of transfer current was passed from the transfer roller, the occurrence of transfer defects was reduced, but since a large amount of transfer current flowed from the transfer roller to the latent image carrier, the latent image carrier was damaged. It was confirmed that inconvenience would occur. Further, in a system having a high process speed, the time during which the transfer current can be applied to the transfer material is shortened, and it is becoming difficult to obtain a satisfactory image.

On the other hand, studies are being conducted to improve the transfer characteristics of toner in a contact charging system. For example, Patent Kaihei 8-36
Japanese Patent No. 316 proposes an attempt to obtain good image quality even in a contact transfer system by using a developer in which two kinds of external additives having different average particle diameters are externally mixed with a toner resin base. However, since two types of external additives having different average particle diameters are used to improve the fluidity of the toner, it is difficult to optimize the addition amount of both external additives, and it is difficult to control the charge amount. It is thought that Further, if the particle size of the toner particles is reduced in order to obtain a high-quality image, the fluidity of the developer deteriorates, and there is a problem that the developer scatters at the time of transfer, or voids occur. In order to solve these problems, the toner particle size and the toner cohesion are optimized, but the transfer conditions are adequate considering the toner charge amount on the latent image carrier and the toner charge amount on the transfer material. There is no example examined in. As described above, the contact transfer type image forming apparatus in which the physical properties of the toner are taken into consideration is still insufficient, and there are many points to be improved.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image which can obtain a good copy image by utilizing an image forming apparatus, that is, a contact transfer means, in which the problems of the prior art are greatly improved. To provide a forming apparatus. A further object of the present invention is to provide an image forming apparatus that does not cause damage such as transfer failure. A further object of the present invention is to provide an image forming apparatus which does not have a hollow portion during transfer. A further object of the present invention is to provide an image forming apparatus capable of always obtaining an image with high density, high resolution and little fog even in a developing system using reversal development, which has a high process speed.

[0008]

Means for Solving the Problems The inventors of the present invention have reached the following invention in the course of intensive studies to solve the above-mentioned various problems and develop an image forming apparatus which meets the above-mentioned object of the present invention. . That is, the present invention relates to (i) a latent image carrier for carrying an electrostatic latent image, and (ii) a toner carrier for carrying toner to a developing area facing the latent image carrier while carrying the toner. A developing device for forming an electrostatic latent image formed on the latent image carrier by using a toner carried on the toner carrier to form a toner image, and (iii) the above A contact transfer member for contacting the latent image carrier to form a nip as a transfer site is provided, and a transfer charge is applied to the transfer material conveyed to the transfer site and carried by the latent image carrier. An image forming apparatus having at least a transfer device for transferring a toner image, comprising:
The constant current control means for outputting a predetermined current value,
With a constant voltage control unit that outputs at a constant voltage value, transfer
Switching between constant current control and constant voltage control according to the size of the material
In addition, the latent image carrier has a peripheral speed of 180 mm / s or more, and the charge amount (a) of the toner image developed on the latent image carrier is 6 to 30 mC in absolute value. /
and is set so that the ratio of the charge amount (b) of the toner on the transfer material after transfer to the above charge amount (a) satisfies 1 <b / a <1.5 (1), Further, the image forming apparatus is characterized by using a toner having an aggregation degree of 1 to 30% at 25 ° C. and 60% RH.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors consider the reason why the image forming apparatus of the present invention having the above-described structure exerts its original effect as follows. That is, the present inventors
As a result of diligent studies to solve the above problems, even when the peripheral speed of the latent image carrier is relatively high at 180 mm / s or more, the charge amount (a) of the toner on the latent image carrier and the transfer material If the charge amount (b) of the toner and the cohesion degree of the toner to be used are maintained in an appropriate range, the transfer is sufficiently performed at the time of contact transfer, resulting in problems such as transfer failure, scattering, and voids. It has been found that the above problems can be solved without the occurrence of. Then, as a result of various studies on the range in which the charge amount (a) of the toner on the latent image carrier and the charge amount (b) of the toner on the transfer material are appropriate, the latent image carrier is shown for the following reasons. charge amount of the toner (a) above is the absolute value of 6 to 30mC / k g, and the charge amount of the toner on the transfer material (b) is the 1 <b / a <1.5, excellent above It has been found that the range is suitable for obtaining the effect. Also,
The proper range of the cohesion of the toner used is 25
It was also found that the aggregation degree at 60 ° C. and 60 RH% was 1 to 30%.

[0010] charge of the toner on the latent image bearing member when (a) is less than 6mC / k g in absolute value, is transferred to the charge amount of the toner on the latent image bearing member is less hesitation. Further, if a large amount of transfer current is passed during transfer in order to obtain sufficient transfer toner, not only the transfer current flows through the transfer material to the latent image carrier, but also image defects such as scattering occur, which is not preferable. On the other hand, the charge amount (a) is 30 mC / k in absolute value.
If it exceeds g, it is difficult for the toner to be transferred from the latent image carrier to the transfer material, and transfer failure occurs. Further, when the ratio (b / a) of the charge amount (b) of the toner on the transfer material to the charge amount (a) of the toner on the latent image carrier is 1 or less, problems such as transfer failure and hollow defects may occur. It tends to occur, and b / a is 1.5
The above case is not preferable because the scattering becomes worse. More preferably, the value of b / a is 1.05 to 1.45. The toner used is 25 ° C, 60RH%
When the cohesion degree below is 1 to 30%, the adhesive force between the toners and the adhesive force between the toner and the latent image carrier are small, so that the peripheral speed of the latent image carrier is 180 mm / s or more, which is relatively high. Even in this case, problems such as omission of image and transfer tailing do not occur during contact transfer.

In the present invention, the charge amount of the toner on the latent image carrier and the charge amount of the toner on the transfer material were determined by the suction Faraday gauge method. In this suction type Faraday gauge method, the outer cylinder is pressed against the surface of the latent image carrier or transfer material, and all the toner on a certain area on the latent image carrier or transfer material is sucked and collected by the inner filter. Then, the mass of the sucked toner is calculated from the increase in the weight of the filter. At the same time, the charge amount of the toner on the latent image carrier and the charge amount of the transfer material toner are obtained by measuring the charge amount accumulated in the inner cylinder electrostatically shielded from the outside. By calculating the ratio of the obtained mass and charge amount, the charge amount (a) of the toner on the latent image carrier, the charge amount (b) of the toner on the transfer material, and their ratio (b / a) are calculated. ) Can be calculated.

The aggregation degree of the toner used in the present invention is measured by using a powder tester (manufactured by Hosokawa Micron Co., Ltd.) under conditions of 25 ° C. and 60 RH%. Sieves having openings of 75 μm, 150 μm, and 250 μm are arranged in this order from the bottom, 5 g of toner is put into the sieve having openings of 250 μm, and a voltage of 2.4 v is applied to the vibration system to apply vibration for 15 seconds. After the vibration, the weight of the toner on each sieve was measured, and the weights of 0.2, 0.12, and 0.04 were applied to the weights, respectively, and the results were calculated as a percentage.

In the present invention, the weight average diameter X (μm) of the toner used preferably satisfies the following condition (2). 3.5 ≦ X ≦ 9.0 (2) When X (μm) is less than 3.5 μm, 25 ° C., 60
Since the degree of toner aggregation under RH% is large, the adhesive force between the toner particles and the adhesive force between the toner and the latent image carrier are large, and problems such as defective transfer and hollow defects occur. If it exceeds 9.0 μm, the toner becomes large with respect to a small latent image on the latent image carrier, so that it becomes difficult to achieve high image quality.

The weight average particle diameter of the toner of the present invention is the Coulter Counter TA-II or Coulter Multisizer.
It was determined from the measurement of particle size distribution using II (manufactured by Coulter). As the electrolytic solution, a 1 wt% NaCl aqueous solution prepared by using primary sodium chloride is used. As the electrolytic solution, for example, ISOTON-II (manufactured by Coulter Scientific Japan Co.) can be used. As a specific measuring method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the volume distribution is measured by measuring the volume and number of toner particles of 2 μm or more by using the 100 μm aperture as an aperture with the measuring device. Then, the number distribution was calculated, and the weight-based weight average diameter X (the median value of each channel was used as a representative value for each channel) calculated from the volume distribution according to the present invention was calculated.

In the image forming apparatus of the present invention, the transfer unit includes a constant current control unit that outputs a predetermined current value,
That having a constant voltage control means for outputting at a predetermined low voltage.
That is, when only the constant current control unit is provided, when a small-sized transfer material is passed, the transfer current is transferred to the non-sheet passing area due to the difference in resistance between the sheet passing area and the non-sheet passing area. Flow easily, the amount of transfer charge applied to the back surface of the transfer material decreases, and transfer defects such as transfer omissions easily occur. on the other hand,
When only the constant voltage control means is provided, the low voltage value is usually set so as not to cause the transfer omission even in the transfer material of the small size, and thus the transfer material is transferred when the transfer material of the large size is passed. The charge amount is likely to be excessive, resulting in a transfer failure.

The contact transfer device that can be used in the present invention is not limited to the roller type, and any contact charging device such as a belt type or a combination of a belt and an electrode blade can be used. FIG. 1 shows a schematic side view of a main part of an image forming apparatus using a transfer roller as an example. In the illustrated apparatus, a cylindrical latent image carrier 1 that extends in a direction perpendicular to a paper surface and rotates in an arrow direction is shown. A conductive transfer roller 2 that comes into contact with this is provided.

In FIG. 1, the periphery of the latent image carrier 1 is
A primary charging device for uniformly charging the surface, a light source such as image-modulated laser light or reflected light from an original is projected on the charging surface, and the potential of the relevant portion is attenuated to form an electrostatic latent image. An exposure unit for forming, a developing unit, a cleaner for removing toner remaining on the surface of the latent image carrier after transfer, and other members necessary for image formation are provided, but they are omitted.

The transfer roller 2 includes a core metal 2a and a conductive elastic layer 2
b, the conductive elastic layer 2b has a conductive material such as carbon dispersed therein, for example, a polyurethane resin or an ethylene-propylene-diene terpolymer (EPD).
It is made of an elastic body having a volume resistance of 10 ⁶ to 10 ¹⁰ Ω · cm such as M). The contact pressure used in the present invention is preferably a linear pressure of 3 g / cm or more. The linear pressure is calculated by the following formula (3). If the contact pressure is less than 3 g / cm, it is not preferable because the transfer material is easily shaken and a transfer failure due to insufficient transfer current occurs.
Particularly preferably 20 g / cm 2 or more (more preferably 25 g / cm 2 or more)
˜80 g / cm).

A bias is applied to the core metal 2a by a constant voltage power source 3. As the bias condition, a current value of 0.
1 to 50 μA and voltage (absolute value) of 100 to 5000 V (more preferably 500 to 4000 V) are preferable. Figure 2
Is an example of a contact transfer device that uses a constant voltage power source and a constant current power source for the core metal 2a. This device is a device that can switch the transfer power source according to the size information of the transfer material that is passed.

The latent image carrier which can be used in the present invention is not limited to the electrophotographic photosensitive member, and may be an electrostatic recording derivative or a magnetic recording magnetic substance, and after transfer to the latent image carrier is possible. The formation principle and process are also arbitrary. Further, the latent image carrier is not limited to the drum type, but may be a belt type, a web type, a sheet type or the like.

The transfer material that can be used in the present invention may be an intermediate transfer belt or an intermediate transfer member such as the same as well as a commercially available paper or OHP film.

Next, the image forming apparatus of the present invention will be described. An example of the image forming apparatus of the present invention is shown in FIG. 3, but the image forming apparatus of the present invention is not limited to this.
In FIG. 3, the latent image carrier 1 is made of an organic photoconductor, and after being uniformly charged by the charging roller 6, a laser beam L modulated by an image signal is irradiated by a laser scanner (not shown) to obtain a desired electrostatic charge. A latent image is formed. This electrostatic latent image is reversely developed by the toner T contained in the developing device 7 and visualized as a toner image. On the other hand, the transfer material P fed by a sheet feeding means (not shown) has a pair of conveying rollers 8a and 8b, and transfer entrance guides 9a and 9b.
Is transferred to a transfer portion by a voltage applied with a voltage having a polarity opposite to that of the toner to form a nip N with the latent image carrier 1.
Thus, the toner image is transferred onto the transfer material P. After that, the transfer material P is transported by the transport guide 11 after the excessive transfer current is removed by the static elimination needle 10, and is fixed by the fixing device 13.
And the toner image on the transfer material P is thermally fixed. After the transfer, the toner remaining on the surface of the latent image carrier is cleaned by the cleaner 1.
2 and the same image forming process is repeated again.

For the toner used in the image forming apparatus of the present invention, it is preferable to use a charge control agent mixed with toner particles (internal addition) or mixed with toner particles (external addition).
The charge control agent makes it possible to control the charge amount adapted to other systems such as a developing system, and particularly in the present invention, this makes it possible to optimize the charge amount of the toner on the transfer material. And good transferability can be obtained.

When the toner used in the present invention has a negative triboelectrification property, examples of charge control agents include organic salicylate metal salts, alkylsalicylic acid metal salts, dialkylsalicylic acid metal salts and naphthoic acid metal salts. It is desirable to contain a metal complex salt; a dye such as a monoazo dye; a monoazo dye derivative such as a metal complex salt of a monoazo dye. As the negative charge control agent of the dye compound, for example,
Examples thereof include those represented by the following general formula (I).

[0025] (In the formula, M represents a coordination center metal, and examples thereof include Cr, Co, Ni, Mn, and Fe having a coordination number of 6. Ar is an aryl group such as a phenyl group and a naphthyl group. These may have a substituent, and examples of the substituent in this case include a nitro group, a halogen group, a carboxyl group, an anilide group, an alkyl group having 1 to 18 carbon atoms and an alkoxy group. X, X ′, Y and Y ′ are —O—, —CO—, —NH—, or —NR.
-(R is an alkyl group having 1 to 4 carbon atoms). A ⁺ represents hydrogen, sodium ion, potassium ion, ammonium ion, or aliphatic ammonium ion. )

Particularly effective charge control agents usable in the present invention include, for example, monoazo iron complex salts represented by the following formula (II). (In the formula, X ₁ and X ₂ represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group or a halogen atom,
X ₁ and X ₂ may be the same or different, m and m ′ represent an integer of 1 to 3, Y ₁ and Y ₃ represent a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group. , A sulfonamide group, a mesyl group, a sulfonic acid group, a carboxyester group, a hydroxy group, an alkoxy group having 1 to 18 carbon atoms, an acetylamino group, a benzoylamino group or a halogen atom, and Y ₁ and Y ₃ are the same. Or may be different, n and n'represent an integer of 1 to 3, Y ₂ and Y ₄ represent a hydrogen atom or a nitro group, A ⁺ represents a cation ion, and 75 to 98 mol% It has an ammonium ion, and also has a hydrogen ion, a sodium ion, a potassium ion, or a mixed ion thereof. )

When the toner used in the present invention has a positive triboelectric charging property, it may be used as a charge control agent.
For example, modified products of nigrosine and fatty acid metal salts;
Tributylbenzylammonium 1-hydroxy-4-
Naphtosulfonates, quaternary ammonium salts such as tetrabutylammonium tetrafluoroborate, and onium salts such as phosphonium salts which are analogs thereof and lake pigments thereof, triphenylmethane dyes and lake pigments thereof (as a lake agent). Are phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanic acid, ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; Diorganotin borates such as dibutyl tin borate; guanidine compounds, imidazole compounds and the like. These may be used alone or in combination of two or more. Among these, a triphenylmethane compound and a quaternary ammonium salt whose counter ion is not halogen are preferably used.

Further, a homopolymer (homopolymer) of a monomer represented by the following general formula (III) and at least one copolymerizable monomer such as styrene, an acrylic acid ester and a methacrylic acid ester described below are included. Can be used. (In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ and R ₃ are substituted or unsubstituted alkyl groups (preferably,
Represents a carbon number of 1 to 4). The charge control agent in these cases also has an action as (all or part of) the binder resin.

The content of the charge control agent is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the binder resin of the toner,
Particularly, 0.2 to 3 parts by mass is preferable. If the proportion of the charge control agent is too large, the fluidity of the toner deteriorates and fog is likely to occur. On the other hand, if the proportion is too small, it is difficult to obtain a sufficient charge amount.

As the binder resin constituting the toner that can be used in the image forming apparatus of the present invention, it is preferable to use vinyl resin or polyester resin as the main component. Examples of the vinyl-based monomer for producing the vinyl-based resin include styrene, o-methylstyrene,
m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene,
2,4-dimethylstyrene, pn-butylstyrene,
Styrene and its derivatives such as p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene and pn-dodecylstyrene; ethylene, Ethylenically unsaturated monoolefins such as propylene, butylene, isobutylene; unsaturated polyenes such as butadiene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride; vinyl acetate, vinyl propionate, Vinyl ester acids such as vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate. , Me Α-methylene aliphatic monocarboxylic acid esters such as phenyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, acrylic Acid n-octyl, dodecyl acrylate,
Acrylic esters such as 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl methyl ether,
Vinyl ethers such as 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 and N-vinyl pyrrolidone N-vinyl compounds; vinylnaphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.

Further, unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenylsuccinic acid, fumaric acid and mesaconic acid; maleic anhydride, citraconic anhydride, itaconic anhydride, alkenylsuccinic anhydride Unsaturated dibasic acid anhydrides such as: maleic acid methyl 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, itaconic acid methyl ester Half ester of unsaturated dibasic acid such as half ester, alkenyl succinic acid methyl half ester, fumaric acid methyl half ester and mesaconic acid methyl half ester; unsaturated dibasic acid such as dimethyl maleic acid and dimethyl fumaric acid
Di esters, acrylic acid, methacrylic acid, crotonic acid,
Α, β-unsaturated acids such as cinnamic acid; crotonic anhydride,
Α, β-unsaturated acid anhydrides such as cinnamic acid anhydride,
An anhydride of β-unsaturated acid and lower fatty acid; alkenylmalonic acid, alkenylglutaric acid, alkenyladipic acid,
Examples thereof include monomers having a carboxyl group such as 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- Examples thereof include monomers having a hydroxyl group such as hydroxy-1-methylhexyl) styrene.

Among the vinyl resins obtained by using one kind or two or more kinds of these monomers, the glass transition temperature in the present invention is 45 to 80 ° C., preferably 55 to 80 ° C.
70 ° C. and number average molecular weight (Mn) of 2,500 to 5
50,000, preferably 3,000 to 20,000, and a weight average molecular weight (Mw) of 10,000 to 1,50.
10,000, preferably 25,000-1,250,0
It is advisable to use No. 00 as the main component of the binder resin. In the present invention, as a more preferable form of the binder resin, a developer is dissolved in a solvent, and a molecular weight distribution of the filtrate is measured by gel permeation chromatography (GPC). 3,000 to 30,000, more preferably 3,
500-20,000 area, and 50,000-
1,200,000, preferably 80,000 to 1,1
0,000, more preferably 100,000-1,0
Each of them has a peak in the area of 0,000.

The polyester resin preferably used as the binder resin of the toner used in the present invention has an alcohol component in an amount of 45 to 55 mol% in all components.
A composition having an acid component of 5 to 45 mol% is preferable. As the alcohol component, for example, ethylene glycol,
Propylene glycol, 1,3-butanediol, 1,
4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, a bisphenol derivative represented by the following formula (IV); diols represented by the following formula (V), and the like.

[0035]

[0036] (In the formula, R is an ethylene group or a propylene group,
x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10. )

The divalent carboxylic acid contained in the total acid component in an amount of 50 mol% or more includes, for example, benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and phthalic anhydride, or their anhydrides; succinic acid, Alkyldicarboxylic acids such as adipic acid, sebacic acid, azelaic acid or the anhydrides thereof, and further succinic acid substituted with an alkyl group having 6 to 18 carbons or the anhydride thereof;
Examples thereof include unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid and itaconic acid, and anhydrides thereof.

Further, as the alcohol component other than the above, glycerin, pentaerythritol, sorbit, sorbitan, and further, for example, polyhydric alcohols such as oxyalkylene ether of novolac type phenol resin, trimellitic acid as the acid component other than the above. And polyvalent carboxylic acids such as pyromellitic acid, benzophenonetetracarboxylic acid and their anhydrides.

In the practice of the present invention, the components of the polyester resin which are particularly preferable as the binder resin include the bisphenol derivative represented by the above formula (IV) as the alcohol component, and the acid component as phthalic acid or terephthalic acid. Examples thereof include isophthalic acid or its anhydride, succinic acid, n-dodecenylsuccinic acid, or its anhydride, and dicarboxylic acids such as fumaric acid, maleic acid and maleic anhydride. Preferred examples of the crosslinking component include trimellitic anhydride, benzophenonetetracarboxylic acid, pentaerythritol, and oxyalkylene ether of novolac type phenol resin.

Further, among the polyester resins obtained above, the glass transition temperature is 40 to 90 ° C., preferably 4
5 to 85 ° C., and the number average molecular weight (Mn) is
1,000-50,000, preferably 1,500-2
10,000, more preferably 2,500 to 10,000
0, weight average molecular weight (Mw) of 3,000 to 3,000
50,000, preferably 10,000 to 2,500,0
00, more preferably 40,000 to 2,000,0
It is recommended to use the one of 00.

The acid value of the polyester resin is 2.5.
-80 mgKOH / g is preferable, more preferably 5-60 mgKOH / g, still more preferably 1
It is 0 to 50 mgKOH / g, and the OH value is preferably 80 or less, more preferably 70 or less, and further preferably 60 or less. When the acid value of the polyester resin is less than 2.5, the amount of the carboxyl group-related aggregates of the binder resin formed is small, and the charging speed tends to be slow, which is not preferable. Further, when the acid value of the polyester resin exceeds 80, a large number of carboxyl groups which do not form a part of the aggregated aggregate are present in the polyester resin, so that the polyester resin is easily attacked by moisture, which deteriorates environmental stability. Is likely to occur, which is not preferable. Further, when the OH value of the polyester resin exceeds 80, a large number of OH group aggregates are formed, so that the polyester resin is apt to be attacked by water, and therefore environmental stability is likely to deteriorate, which is not preferable.

In the present invention, one or more polyesters having different compositions, molecular weights, acid values and / or OH values may be mixed and used as a binder resin. In the present invention, polyurethane, Epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, etc. may be mixed with the above binder resin, if necessary. You can

Further, as the colorant of the toner regardless of whether it is one component or two components, carbon black, titanium white,
All other pigments and dyes can be used. For example, when the toner is used as a magnetic color toner in the present invention, the dye may be C.I. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I.
Mordant Red 30, C.I. I. Direct Blue 1,
C. I. Direct Blue 2, C.I. I. Acid Blue 9, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. Mordant Blue 7, C.I. I. Direct Green 6, C.I.
I. Basic Green 4, C.I. I. Basic green 6 and the like can be mentioned. Pigments include yellow lead, cadmium yellow, mineral fast yellow, navel yellow, naphthol yellow S, Hansa yellow G, permanent yellow NCG, tartrazine lake, red lead yellow lead, molybdenum orange, permanent orange GT.
R, Pyrazolone Orange, Benzidine Orange G, Cadmium Red, Permanent Red 4R, Watching Red Calcium Salt, Eosin Lake, Brilliant Carmine 3B, Manganese Purple, Fast Violet B, Methyl Violet Lake, Navy Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue lake, phthalocyanine blue, fast sky blue, indanthrene blue BC, chrome green, chromium oxide, pigment green B, malachite green lake, final yellow green G and the like can be mentioned. The amount of the colorant used is 0.1 to 60 with respect to 100 parts by mass of the binder resin.
Parts by mass, preferably 0.5 to 50 parts by mass.

When the toner is used as a magnetic toner in the present invention, the magnetic substance may also serve as a colorant. As the magnetic material contained in the magnetic toner of the present invention,
Iron oxide such as magnetite, maghemite, and ferrite,
And iron oxides containing other metal oxides; metals such as Fe, Co, Ni, or these metals and Al, Co, C
u, Pb, Mg, Ni, Sn, Zn, Sb, Be, B
Examples thereof include alloys with metals such as i, Cd, Ca, Mn, Se, Ti, W and V, and mixtures thereof.

As the magnetic material, conventionally, iron trioxide (Fe ₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), zinc iron oxide (ZnFe ₂ O ₄ , iron yttrium oxide (Y _{3) is used.} Fe ₅ O
₁₂ ), iron cadmium oxide (CdFe ₂ O ₄ ), iron gadolinium oxide (Gd ₃ Fe ₅ O ₁₂ ), iron oxide copper (CuFe
₂ O ₄ ), lead iron oxide (PbFe ₁₂ O ₁₉ ), iron nickel oxide (NiFe ₂ O ₄ ), neodymium iron oxide (NdFe ₂ O ₃ ), barium iron oxide (BaFe ₁₂ O ₁₉ ), magnesium iron oxide (MgFe) ₂ O ₄ ), iron manganese oxide (MnFe ₂ O ₄ ),
Known are lanthanum iron oxide (LaFeO ₃ ), iron powder (Fe), cobalt powder (Co), nickel powder (Ni), and the like.

In the present invention, the above magnetic materials are used alone or in combination of two or more. Particularly suitable magnetic materials for the purposes of the present invention are fine powders of ferric tetroxide or γ-iron sesquioxide. These ferromagnetic materials have an average particle size of about 0.05 to 2 μm, and have magnetic properties of 795.8 kA / m applied, coercive force of 20 to 150 kA / m, and saturation magnetization of 5
0~200Am ² / k g (preferably 50~100Am ²
/ K g), it is desirable for residual magnetization 2~20Am ² / kg. The magnetic substance is used in an amount of 10 to 200 parts by mass, preferably 20 to 15 parts by mass with respect to 100 parts by mass of the binder resin.
It is 0 part by mass.

In the present invention, it is a good example to incorporate one or two or more releasing agents in the toner.
Examples of the releasing agent used in the present invention include aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, and paraffin wax; oxidized polyethylene wax, block copolymer waxes thereof, and other aliphatic waxes. Oxides of hydrocarbon waxes; waxes containing fatty acid esters such as carnauba wax, sazol wax, montanic acid ester wax as a main component, and fatty acid esters such as deoxidized carnauba wax partially or wholly deoxidized Things are included.

Further, saturated straight-chain fatty acids such as palmitic acid, stearic acid and montanic acid; unsaturated fatty acids such as blancinic acid, eleostearic acid and varinaric acid;
Saturated alcohols such as stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubayl alcohol, ceryl alcohol, and melissyl alcohol; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; Saturated fatty acid bisamides such as methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, hexamethylenebisstearic acid amide; ethylenebisoleic acid amide,
Unsaturated fatty acid amides such as hexamethylene bisoleic acid amide, N, N'-dioleyl adipamide, N, N'-dioleyl sebacic acid amide; m-xylene bisstearic acid amide, N, N'-di Aromatic bisamides such as stearylisophthalic acid amide; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate, magnesium stearate (generally called metal soap); styrene and aliphatic hydrocarbon wax Waxes grafted with vinyl monomers such as acrylic acid; partial esterification products of fatty acids such as behenic acid monoglyceride and polyhydric alcohols; methyl ester compounds having hydroxyl groups obtained by hydrogenation of vegetable oils, etc. Is mentioned. In the present invention, the above releasing agents can be used alone or in combination of two or more kinds, and the amount of the releasing agent used is 0.1 with respect to 100 parts by mass of the binder resin.
˜20 parts by mass, preferably 0.5 to 10 parts by mass.

Further, the toner used in the present invention is mixed with an inorganic fine powder or a hydrophobic inorganic fine powder in order to improve environmental stability, charge stability, development stability, fluidity, storability and the like. It is preferable. Examples of these include silica fine powder, titanium oxide fine powder, and hydrophobized products thereof. These are preferably used alone or in combination of two or more.

As the silica fine powder, both so-called dry method produced by vapor phase oxidation of a silicon halogen compound or dry silica called fumed silica and so-called wet silica produced from water glass can be used. However, dry silica having less silanol groups on the surface and inside the silicic acid fine powder and having no production residue such as Na ₂ OSO ₃ is preferable. Further, in the case of wet silica, it is possible to obtain a composite powder of silica and another metal oxide in the manufacturing process, for example, by using another metal halogen compound such as aluminum chloride or titanium chloride together with a silicon halogen compound. The silica fine powder also includes them.

Further, the silica fine powder is preferably hydrophobized. Hydrophobization is performed by chemically treating with an organic silicon compound that reacts with or physically adsorbs to silica fine powder. A preferred method for hydrophobizing treatment is, for example, after treating dry silica fine powder produced by vapor phase oxidation of a silicon halide with a silane coupling agent, or simultaneously with treating with a silane coupling agent, an organosilicon such as silicone oil. Examples include a method of treating with a compound. The silane coupling agent treatment of the silica fine powder is, for example, a dry treatment of reacting the vaporized silane coupling agent with the silica fine powder grounded by stirring or the like, or silane in a dispersion liquid in which silica is dispersed. It can be carried out by a generally known method such as a wet method in which a coupling agent is dropped and reacted.

Examples of the silane coupling agent used in the hydrophobizing treatment include dimethyldichlorosilane, trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, and vinyltrichlorosilane. Examples thereof include ethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinylchlorosilane and dimethylvinylchlorosilane.

Examples of the organic silicon compound include silicone oil and the like. The preferred silicone oil has a viscosity of about 30 to 10 at 25 ° C.
00 centistokes are used. When the fine silica powder is negatively charged silica, examples of silicone oils that can be used include dimethyl silicone oil, alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil. preferable. When the fine silica powder is positively charged silica, the silicone oil should be treated with a silicone oil having an organo group having at least one nitrogen atom in the side chain or a nitrogen-containing silane coupling agent. Is preferred.

The method for treating silicone oil is, for example, a method in which silica fine powder treated with a silane coupling agent and silicone oil are directly mixed using a mixer such as a Henschel mixer, and silicone oil is added to a suitable solvent. After dissolving or dispersing, a method of mixing with a fine silica powder as a base and removing the solvent may be used.

As a preferred method of hydrophobizing the silica fine powder, there is a method of treating the silica fine powder with dimethyldichlorosilane, then with hexamethyldisilazane, and finally with silicone oil. Thus, it is particularly preferable to treat the silica fine powder with two or more kinds of silane coupling agents and subsequently to treat with silicone oil, since the degree of hydrophobicity can be effectively increased. Titanium oxide fine powder that has been subjected to a hydrophobizing treatment on the above silica fine powder and further a silicone oil treatment is also preferably used in the present invention.

Among the above silica fine powders, those having a specific surface area of 30 m ² / g or more (particularly preferably 50 to 400 m ² / g) by nitrogen adsorption measured by the BET method are preferably used.

To the toner used in the present invention, various external additives such as a lubricant other than silica fine powder or titanium oxide fine powder, an abrasive, and a fluidity imparting agent may be added, if necessary. Examples of the lubricant include Teflon, zinc stearate, and polyvinylidene fluoride.
Of these, polyvinylidene fluoride is preferable. Examples of the polishing agent include cerium oxide, silicon carbide, and strontium titanate. Among them, strontium titanate is preferable. Examples of the fluidity-imparting agent include titanium oxide and aluminum oxide, and among them, hydrophobic ones are particularly preferable. Anti-caking agent, or
For example, carbon black, zinc oxide, antimony oxide,
A small amount of a conductivity-imparting agent such as tin oxide, and white particles and black particles having opposite polarities can be used as a developing property improver. The resin fine particles, the inorganic fine powder or the hydrophobic inorganic fine powder mixed with the toner is preferably used in an amount of 0.1 to 5 parts by mass (preferably 0.1 to 3 parts by mass) with respect to 100 parts by mass of the toner. .

When the toner used in the present invention is a non-magnetic toner which also uses a carrier, examples of usable carriers include non-coated carriers such as iron powder, ferrite powder, magnetite powder and glass beads, and styrene. A carrier coated with an acrylic resin, a silicone resin, a fluorine-modified acrylic resin, or a granulation carrier can be used. in this case,
The amount of carrier used is 10 per 100 parts by weight of toner.
˜1000 parts by mass (preferably 30 to 500 parts by mass) should be used. The particle size of the carrier is 4 to 100
μm (preferably 10 to 80 μm, more preferably 20)
.About.60 .mu.m) are preferably used in matching with the toner of the present invention.

The toner used in the present invention is prepared by thoroughly mixing the above-mentioned toner constituent materials with a mixer such as a ball mill, and then using a heat kneader such as a heating roll, kneader or extruder to melt, knead, and knead the mixture. It can be obtained by kneading, cooling and solidifying, crushing, and strict classification.

[0060]

EXAMPLES The basic constitution and features of the present invention have been described above. The present invention will be specifically described below with reference to Examples and Comparative Examples. However, the invention is not limited to these examples. The number of parts in the examples is part by mass.

Example 1-Polyester resin 100 parts-Magnetic iron oxide 90 parts-Low molecular weight ethylene-propylene copolymer 4 parts-Metal complex salt compound (of the above chemical formula (II)) 2 parts The above polyester resin is It is obtained by condensation at a ratio of bisphenol A / terephthalic acid / n-dodecenyl succinic acid / trimellitic acid / diethylene glycol = 20/38/15/5/22 (molar ratio). Also,
The acid value of the resin is 27, the hydroxyl value is 8, the weight average molecular weight (Mw) is 550,000, and the number average molecular weight (Mn) is 4800.
And the glass transition temperature (Tg) was 57 ° C.

The above materials were premixed with a Henschel mixer, and then melt-kneaded at 130 ° C. with a twin-screw kneading extruder. After the kneaded product was allowed to cool, it was crushed using a fine crusher using a jet stream, and further classified using an air classifier to obtain a magnetic toner having a weight average particle diameter of 7.0 μm. Hexamethyldisilazane 2 per 100 parts of this magnetic toner
Henschel mixer with 1.0 part of hydrophobic dry silica fine particles (BET specific surface area 300 m ^{2 /} g) treated with 5 parts and 10 parts of dimethyl silicone oil (both 100 parts of silica raw material) and 3 parts of strontium titanate fine particles. Externally added to obtain a negatively chargeable magnetic toner having hydrophobic dry silica fine particles and strontium titanate fine particles on the surface of the magnetic toner particles. 25 ° C., 60 RH% of the toner
The aggregation degree below was 14.1%.

The obtained negatively chargeable magnetic toner was modified as shown in FIG.
By P215, plain paper of different sizes (A3 size and B5 size 64g / m ² paper) is alternately changed every 500 sheets, and a continuous 40,000 sheet passing test (image evaluation) is performed under normal temperature and normal humidity environment ( It carried out under 23 degreeC and 60 RH%). Here, the peripheral speed (process speed) of the latent image carrier is 220 mm / s, and the peripheral speed of the developer carrier is 396 mm / s.
set to s. In digital copiers, diameter is 30m
A latent image carrier having an OPC photosensitive layer on an aluminum cylinder of m was charged to −700 V by a charging roller, a digital latent image was formed by image scanning with a laser beam, and frictionally charged by a developing sleeve. Reverse development was performed with a negatively chargeable magnetic toner to obtain a toner image. A DC bias of −580 V and an AC bias V _{pp of} 800 V (frequency 1800 Hz) were applied to the developing sleeve.

The magnetic toner image on the latent image carrier was electrostatically transferred onto plain paper by roller transfer. At that time, A3
20 μA for constant-size plain paper
For B5 size plain paper, perform constant voltage control. 2
kV was applied to the transfer roller. A transfer roller made of polyurethane resin in which carbon was dispersed was used. The resistance value of the roller was 10 ⁸ Ω · cm. The static paper after transfer was separated from the latent image carrier after static elimination, and the magnetic toner image on the plain paper was fixed by a hot roll fixing device having a fixing roller and a pressure roller. Evaluation was performed according to the following method and evaluation criteria. Table 1 shows the cohesion degree and the charge amount of the toner, and Table 2 shows the evaluation results. The same operation was performed in other Examples and Comparative Examples described later.

(1) Image Quality Scattering Characters of "Den" of about 2 mm square were copied, and the level of sharpness of characters such as toner scattering around the characters of "Den" was evaluated by observation with an optical microscope. ◯: There is almost no toner scattering around the characters. Δ: A little toner scattering X: A lot of toner scattering Dot reproducibility An independent 1-dot pattern was printed out and the reproducibility of 1 dot was evaluated by optical microscope observation. ○: Dots are reproduced faithfully △: Image has some irregularity ×: Image has a lot of irregularity and reproducibility is poor. The level of dropout of the toner of the character "Den" was evaluated. ○: No voids △: There are some voids, but they can be identified as characters ×: There are voids and the characters are visible

(2) Image Density Evaluation was carried out by maintaining the image density at the end of printing out 20,000 sheets on ordinary plain paper for copying (75 g / m). As the image density, a "Macbeth reflection densitometer" (manufactured by Macbeth Co.) was used to measure the relative density with respect to the print-out image of the original document density of 0.00 white background. (3) Fog was calculated by comparing the whiteness of the transfer paper measured with a fog reflectometer (manufactured by Tokyo Denshoku Co., Ltd.) and the whiteness of the transfer paper after printing solid white.

As a result, as shown in Table 2, it was possible to obtain an image having no transfer defects, excellent image quality, and no fog and high image density through durability. Table 1
The toner charge amount on the latent image carrier shown in is -12.35 m.
Is the absolute value of the C / k g, an average value of those measured at multiple time points over the durability. As a result of the measurement, the toner charge amount on the latent image bearing member was -11.0 to -13.
In the range of 7mC / k g, also the charge amount on the transfer material -
In the range of 14.1~-18.5mC / k g (average value 16.3mC / k g), both were confirmed to be stable.

Example 2 Polyester resin was replaced with styrene / n-butyl acrylate / butyl maleic acid half ester (70/2 in molar ratio).
(Copolymerized 0/10), having a weight average molecular weight (Mw) of 12,000, a number average molecular weight (Mn) of 290000, an acid value of 25, and a Tg of 61.
A magnetic toner having a weight average particle diameter of 6.3 μm was obtained in the same manner as in Example 1 except that the styrene resin at ℃ was used. The toner was externally added in the same manner as in Example 1 to obtain a negatively chargeable magnetic toner. The aggregation degree of this toner at 25 ° C. and 60 RH% was 17.8%. Further, this negatively chargeable magnetic toner was used and evaluated in the same manner as in Example 1. As a result, as shown in Table 2, good results almost equal to those in the case of Example 1 could be obtained.

Reference Example 1 In Example 1, 2 parts of carbon black was added in place of the magnetic powder to obtain a toner having a weight average diameter of 8.9 μm, and 0.8 part of silica fine particles was added to 100 parts of the toner. A toner was manufactured and evaluated in the same manner as in Example 1 except that 1 part of the strontium titanate fine particles was externally added. The aggregation degree of the obtained non-magnetic toner at 25 ° C. and 60 RH% was 5.5%. However, the developing device is for non-magnetic one-component toner. Regard resulting et al, non-magnetic one-component toner, which can hold a sufficient charge amount, it was possible to obtain a good images having throughout stable. The evaluation method was the same as in Example 1 except that postcard (105 g / m ² paper) was used as the transfer material and only constant voltage control (2 kV) was used as the transfer means. As a result, good results could be obtained as shown in Table 2.

Reference Example 2 A toner having a weight average diameter of 3.9 μm was obtained in the same manner as in Example 1 except that 3 parts of phthalocyanine blue was added instead of the magnetic powder, and 100 parts of the toner was added. On the other hand, a toner was manufactured in the same manner as in Example 1 except that 2.0 parts of silica fine particles and 4 parts of strontium titanate fine particles were externally added. 25 ° C. of the toner, 6
The degree of aggregation under 0 RH% was 27.2%. For image evaluation, a two-component developing device was used, Cu-Zn ferrite carrier was used as the carrier, and the surface was coated with a fluororesin / styrene-acrylic resin (= 40/60 (mass ratio)). I used the one. The developer used was a mixture of toner and carrier in a mass ratio of 4:96. Regarding the evaluation method, Example 1 was used except that thick paper (128 g / m ^{2 of} A3 size) was used as the transfer material and only constant current control (20 μA) was used as the transfer means.
The same method was used. As a result, as shown in Table 2, good results could be obtained.

[0071] Example 5   -Styrene / n-butyl acrylate copolymerization suspension (molar ratio 70/30     Mn = 11000; Mw = 2800000; Tg = 60 ° C.) 100 parts   ・ 85 parts of magnetic powder     ・ 2 parts of Nigrosine     ・ Low molecular weight ethylene-polypropylene copolymer 4 parts

Using the above materials, a positively chargeable magnetic toner having a weight average diameter of 5.8 μm was obtained in the same manner as in the toner manufacturing method of Example 1. To 100 parts of this magnetic toner, 1.5 parts of hydrophobic dry silica fine particles (BET specific surface area of 200 m ^{2 /} g) treated with 15 parts of amino-modified silicone oil (amine equivalent: 800) (based on 100 parts of silica base material). Then, 0.8 part of strontium titanate fine particles was externally added by a Henschel mixer to obtain a positively chargeable magnetic toner having hydrophobic dry silica fine particles and strontium titanate fine particles on the surface of the magnetic toner particles. 25 ° C, 60R of the toner
The degree of aggregation under F% was 24.4%.

The positively charged magnetic toner obtained above was subjected to image evaluation by a copying machine in which a modified machine of the digital copying machine GP215 used in Example 1 was further modified for positive toner. Here, the peripheral speed of the latent image carrier is 300 mm / s,
The peripheral speed of the developer carrying member was set to 540 mm / s. In a digital copying machine, a latent image carrier having a photosensitive layer made of amorphous silicon is charged to 400 V by a charging roller on a cylinder made of aluminum having a diameter of 30 mm, and a digital latent image is formed by image scanning with a laser beam and developed. Reverse development was performed with a positively chargeable magnetic toner frictionally charged by a sleeve to obtain a toner image. A DC bias of 250 V and an AC bias of V _pp 700 V (frequency 2700 Hz) were applied to the developing sleeve. Regarding the transfer means, the same procedure as in Example 1 was performed except that a negative transfer bias was applied. As the fixing device, the same heat roll fixing device as in Example 1 was used.

The evaluation results are shown in Table 2. As in the case of Example 1, it was possible to obtain a high-density high-quality image free from transfer defects through durability test. This embodiment is an example in which a positively chargeable magnetic toner, the toner charge amount on the latent image bearing member shown in Table 1 is the absolute value of the + 13.94mC / k g, over the durability It is the average of those measured at multiple time points. As a result of the measurement, the toner charge amount on the latent image bearing member throughout running is, + 11.38~ + 16.50mC / k g is in the range of, also, the charge amount on the transfer material + 14.1～ + 1
It is in the range of 8.5mC / k g (mean + 15.75m
C / k g), as in the case of this case Example 1, it was confirmed that stable.

Example 6 Image evaluation was carried out in the same manner as in Example 1 except that the environment for image formation was changed to a low humidity environment (23 ° C./5 RH%). However, a current of 23 μA was applied to the transfer roller during transfer. All the transfer papers used were left for one week in the above environment. The evaluation result is
It was good all the time shown in Table 2.

Example 7 Image evaluation was carried out in the same manner as in Example 1 except that the environment for image evaluation was changed to a high temperature and high humidity environment (30 ° C./80 RH%). . However, a current of 16 μA was applied to the transfer roller during transfer. All the transfer papers used were left for one week in the above environment. As shown in Table 2, good results could be obtained.

Example 8 In Example 5, the weight average diameter of the toner prepared was 1
Change to 1.5 μm, and add 0.6 parts of silica fine particles and 0.5 parts of strontium titanate fine particles as external additives to be added externally.
A toner was manufactured in the same manner as in Example 1 except that parts were changed. The aggregation degree of the toner at 25 ° C. and 60 RH% was 1.3%. For image evaluation, Example 5
As shown in Table 2, good results could be obtained.

Reference Example 3 In Reference Example 2 , the weight average diameter of the toner prepared was 2.
A toner was manufactured in the same manner as in Example 1 except that the particle size was changed to 9 μm, the silica particles were changed to 2.5 parts, and the strontium titanate particles were changed to 5 parts. 25 ° C. of the toner,
The degree of aggregation at 60 RH% was 29.9%. Image evaluation was performed by the same method as in Reference Example 2 except that only constant voltage control (2 kV) was used for the transfer means, and good results were obtained as shown in Table 2.

Comparative Side 1 In Example 1, the weight average diameter of the toner prepared was 2.
The particle size was 5 μm, and 1.8 parts of the silica fine particles and 5 parts of the strontium titanate fine particles used in Example 1 were added to 100 parts of the toner, and external addition treatment was performed to obtain a negatively chargeable magnetic toner. The aggregation degree of the toner at 25 ° C. and 60 RH% was 74.4%. When image evaluation was carried out in the same manner as in Example 1 except that the above toner was used, the toner on the latent image bearing member was electrostatically firmly attached to the surface of the latent image bearing member because the charge amount of the toner on the latent image bearing member became too high. On the transfer material, making it difficult to transfer to the transfer material and causing transfer failure.
Image generation was stopped after 1000 sheets were printed.

Comparative Example 2 In Example 1, the weight average diameter of the toner prepared was 12.
The particle size was 3 μm, and 0.7 part of the silica fine particles and 0.3 part of the strontium titanate fine particles used in Example 1 were added to 100 parts of the toner, and external addition treatment was performed to obtain a negatively chargeable magnetic toner. The aggregation degree of the toner at 25 ° C. and 60% RH% was 0.7%. Image evaluation was carried out in the same manner as in Example 1 except that the above toner was used, but the charge amount of the toner on the latent image carrier was low. Therefore, transfer from the latent image carrier to the transfer material under the applied transfer bias condition. Difficult to transfer and poor transfer. The obtained image had damage such as scattering and the image density was low.

Comparative Example 3 In Example 1, the weight average diameter of the toner prepared was 10.
The particle size was 8 μm, and 0.8 part of the silica fine particles and 3.5 parts of the strontium titanate fine particles used in Example 1 were added to 100 parts of the toner, and external addition treatment was performed to obtain a negatively chargeable magnetic toner. The aggregation degree of the toner at 25 ° C. and 60 RH% was 42.0%. Also, when displaying images,
Image evaluation was performed in the same manner as in Example 1 except that the transfer control unit was only constant current control. As a result, when 2,000 sheets were passed, a transfer failure occurred in the A3 size plain paper image except in the image area corresponding to the B5 size. Since the obtained images had a lot of damage such as scattering, the evaluation was stopped.

Comparative Example 4 Image evaluation was carried out in the same manner as in Comparative Example 3 except that the transfer control means was only constant voltage control in Comparative Example 3, and even when 1200 sheets of paper were passed through, A3 size plain paper was obtained. Since the image density of the image was low and the image quality was extremely poor due to poor transfer, the evaluation was stopped. The results are shown in Table 1.

[0083]

[0084]

[0085]

As described above, according to the present invention,
In an image forming apparatus that transfers a toner image obtained by reversal development onto a transfer material by contact transfer at a relatively high process speed, the charge amount of the toner on the latent image carrier and the charge of the toner on the transfer material. Quantity and 25 ℃, 60
By defining the aggregation degree of the toner under RH% within an appropriate range, the following excellent effects are exhibited. (1) In the transfer step by contact transfer, good transferability can be stably obtained without causing damage such as transfer failure. (2) Regardless of the image output environment and the type or size of the transfer material, it is possible to stably obtain an image free from image defects such as scattering and voids. (3) Even in a system with a high process speed, since the charge amount of the toner on the latent image carrier is uniformly maintained at an appropriate value, the adhesive force between the toner and the adhesive force between the toner and the latent image carrier are maintained. Can be made small, and a high-density and high-quality image can always be stably obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a transfer process that can be used in the present invention.

FIG. 2 is an explanatory diagram showing an example of a transfer process having a switching control means for constant voltage control and constant current control that can be used in the present invention.

FIG. 3 is a schematic explanatory diagram of an image forming apparatus used in Examples and Comparative Examples of the present invention.

[Explanation of symbols]

1: latent image carrier 2: Transfer roller 2a: core of transfer roller 2b: Conductive elastic layer of transfer roller 3: Constant voltage power supply 4: Constant current power supply 5: Switching control means 6: Primary charging roller 7: Developing device 8a, 8b: Conveyor rollers 9a, 9b: Transfer entrance guide 10: Static elimination needle 11: Transport guide 12: Cleaner 13: Fixing device 131: fixing roller 132: Pressure roller 133: heating member for fixing roller 134: Fixing roller surface temperature detecting element 135: fixing roller bias application power source 136: fixing separation claw L: Laser light P: Transfer material N: Nip

Continuation of front page (56) Reference JP-A-2-282760 (JP, A) JP-A-8-160783 (JP, A) JP-A-7-199688 (JP, A) JP-A-7-114275 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/08 501 G03G 15/16

Claims (3)

(57) [Claims] 1. A latent image carrier for carrying (i) an electrostatic latent image, and (ii) a toner carrier for carrying toner to a developing region facing the latent image carrier while carrying the toner. A developing device for developing an electrostatic latent image formed on the latent image carrier with a toner carried on the toner carrier to form a toner image, and (iii) the latent image A toner having a contact transfer member for contacting with the image carrier to form a nip as a transfer site and imparting a transfer charge to the transfer material conveyed to the transfer site to carry the latent image carrier. In an image forming apparatus having at least a transfer device for transferring an image, the transfer device outputs a constant current control output at a predetermined current value.
Stage and constant voltage control means for outputting a predetermined voltage value.
The constant current control and constant voltage control according to the size of the transfer material.
And a peripheral speed of the latent image carrier is 180 mm / s or more, and the charge amount (a) of the toner image developed on the latent image carrier is 6 in absolute value. To 30 mC / kg, and the ratio of the charge amount (b) of the toner on the transfer material after transfer to the above charge amount (a) satisfies 1 <b / a <1.5 (1) An image forming apparatus using a toner which is set and further has a cohesion degree of 1 to 30% at 25 ° C. and 60% RH. 2. The image forming apparatus according to claim 1, wherein the weight average diameter X (μm) of the toner satisfies the following condition (2). 3.5 ≤ X ≤ 9.0 (2) 3. A constant current for a large-sized transfer material.
Control and constant voltage control for small transfer materials.
The image forming apparatus according to claim 1 or 2, characterized in that the control.