JPH09265205A - Electrostatic charge image developer, electrostatic charge image developing method, and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent electrification characteristics, stable max. image density, low fog, high resolution, and good low temp. fixing property and offset resistance by controlling the saturation water adsorption amt. and the water adsorption rate of a toner into specified ranges. SOLUTION: The saturation water adsorption amt. and the water adsorption rate of a toner are controlled to <=1.0wt.% and >=0.2wt.%/hour, respectively. The saturation water adsorption amt. means the amt. of water in terms of wt.% adsorbed during a toner is left to stand for 24 hours at 30 deg.C and 80% RH. The water adsorption rate is determined by measuring the water adsorption amt. (A) (wt.%) when the toner is left to stand for 24 hours at 20 deg.C and 50% RH, then further leaving the toner to stand for 1 hour at 30 deg.C and 80% RH, measuring the water adsorption amt. (B) (wt.%), and calculating (B)-(A) (wt.%/ hour). When the water adsorption rate is less than 0.2wt.%/hour, such a problem may occur that the toner can not follow changes in the temp. and humidity in a machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developer used in a copying machine, a printer, etc., an electrostatic image developing method and apparatus.

[0002]

2. Description of the Related Art Conventionally, studies and developments regarding a developer, a developing method and an apparatus for an electrostatic charge image developing method, which is a typical image forming method, have been actively conducted. Of these, many are related to the two-component developing method, which is a stable method, and it can be said that the two-component developing method is excellent.

However, the two-component developing method also has problems,
In particular, it is necessary to accurately control the toner density. Otherwise, excellent charging characteristics cannot be obtained, and stable maximum image density cannot be obtained. Further, a developing toner having a low fog and a high resolution cannot be obtained.

On the other hand, as a general problem of the developing toner, there is a demand for a toner having excellent charging characteristics, good low-temperature fixing property, and excellent fixing offset resistance, and at present, it is still a problem in practical use. There is a continuous demand for something that does not have any. Regarding these technologies, recently, Japanese Patent Laid-Open No.
-49587 has been published.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and has excellent charging characteristics, stable stable maximum image density, low fog and high resolution. Moreover, it was made for the purpose of providing an electrostatic charge image developer having good low-temperature fixability and excellent fixing offset resistance, and a developing method and apparatus using the same.

[0006]

The object of the present invention has been achieved by adopting any of the following constitutions.

(1) In an electrostatic charge image developer containing an electrostatic charge image developing toner and a carrier, the saturated moisture adsorption amount of the toner is 1.0% by weight or more, and the moisture adsorption rate is (0.
2% by weight / hour) or more).

(2) An electrostatic image developer containing a toner for developing an electrostatic image and a carrier is used, and the density of the toner is controlled by a sensor which outputs an electric signal according to a change in magnetic permeability of the developer. In an electrostatic charge image developing method of visualizing an electrostatic latent image while controlling the output of this sensor in accordance with a change in humidity, when the saturated moisture adsorption amount of the toner is 1.0% by weight or more, the moisture adsorption A method for developing an electrostatic charge image, wherein the speed is (0.2% by weight / hour) or more.

(3) An electrostatic image developer containing a toner for developing an electrostatic image and a carrier is used, and the density of the toner is controlled by a sensor which outputs an electric signal according to a change in magnetic permeability of the developer. In an electrostatic charge image developing device that visualizes an electrostatic latent image while controlling the output of this sensor according to changes in humidity, when the saturated moisture adsorption amount of the toner is 1.0 wt% or more, An electrostatic charge image developing device having a speed of (0.2% by weight / hour) or more.

Hereinafter, the present invention will be described in more detail.

<Saturated Moisture Adsorption Amount> In the present invention, the saturated moisture adsorption amount means the amount of moisture adsorption when the toner is left at 30 ° C. and 80% RH for 24 hours, which is expressed by weight%.
Actually, the water adsorption amount was determined by the following measuring device.

Hiranuma Trace Moisture Analyzer: AQS-724
(Manufactured by Hiranuma Sangyo Co., Ltd.) Measured toner amount: 0.5 g It should be noted that, for a toner having a saturated moisture adsorption amount of less than 1.0% by weight,
It is not possible to obtain a toner having excellent charging characteristics, good low-temperature fixing property, and good fixing offset resistance. On the other hand, if it exceeds 10% by weight, problems such as charge amount when used at high temperature and high humidity, deterioration of dark decay characteristics, and aggregation of toner when left unattended occur, and the practicality as a toner is lost.

<Moisture Adsorption Rate> The moisture adsorption rate is determined by measuring the amount of moisture adsorption (% by weight) when the toner is left at 20 ° C. and 50% RH for 24 hours, and the value is defined as A. Then 30 ° C
After leaving it at 80% RH for 1 hour, measure the amount of water adsorption afterwards,
Let the value be B. At that time, the water adsorption rate = BA (weight% / hour).

If the water adsorption rate is less than (0.2% by weight / hour), it may not be possible to keep up with the fluctuation of the temperature / humidity in the machine, and if the water adsorption rate exceeds 1.0% by weight / hour. It is difficult to obtain it in the above range of the amount of adsorbed water.

<Toner Density Detection> On the other hand, as a method for controlling the toner density by a sensor which outputs an electric signal according to a change in magnetic permeability of the developer, specifically, Japanese Patent Laid-Open No. 63-63
No. 148281, JP-A-3-59576, JP-A-7
No. 140726 and the like.

In this method, the magnetic permeability is low when the toner concentration of the developer, which is a mixture of the magnetic carrier and the non-magnetic toner, is low, and the magnetic permeability is low when the toner concentration is low, that is, the carrier concentration is high. Get higher In this case, even if the bulk density of the developer rises in an environment where the temperature and humidity are high, the same judgment is made that the toner concentration is apparently low.

However, the output of this sensor is controlled according to the change in humidity, and even if the ambient temperature and humidity conditions change, the same sensor output is always output when the weight ratio of toner to carrier is substantially the same. If it can be adjusted so that it can be obtained, it is easy to control the toner density, and thus it is easy to keep the image density constant at any time.

In the above toner concentration detecting method, if the output of the sensor is increased, it is determined that the toner concentration is decreased, but if the control voltage is decreased, the output of the sensor is decreased. Therefore, in the present invention, when the bulk density rises under high humidity, the control voltage corresponding to it is lowered so that the output of the sensor does not rise, and apparently the toner density is lowered. It is possible to prevent toner from being replenished.

Specifically, the humidity sensor measures the outside air humidity to 7
At 0% RH or higher, the control voltage is lowered by 0.2 V (in this case, the normal control voltage is 7.0 V).

<Binder Resin for Toner> The binder resin for toner according to the present invention is not particularly limited as long as it satisfies the above requirements. In terms of chemical structure, for example, a styrene-based polymer, an acrylic acid ester-based polymer, a methacrylic acid ester-based polymer, a polyester-based polymer, and a copolymer thereof can be said to be typical. However, it can be said that the above range defined by the present invention has a large water adsorption property,
In terms of chemical structure, for example, there is a polyester polymer resin described in JP-A-7-140726.

That is, the saponification value is 300 to 700 [KOHm
g / g], an acid value of 30 to 80 [KOHmg / g], and a chloroform insoluble content of 0.5 to 20% by weight, a polyester resin satisfying the above-mentioned requirements of the present invention is selected. preferable.

Here, the saponification value means the number of milligrams of potassium hydroxide necessary for saponifying 1 g of the sample, and the acid value means the acid contained in 1 g of the sample (the carboxyl group existing at the molecular end). Refers to the number of milligrams of potassium hydroxide required to neutralize.

The saponification value and the acid value are JI
It is measured according to SK 0070.

Further, the chloroform-insoluble matter means a filter paper-impermeable matter when a sample is dissolved in chloroform, and is obtained as follows.

The resin sample was finely pulverized, and 5.00 g of the sample powder that passed through the 40-mesh sieve was collected and placed in a container of 150 ml capacity together with 5.00 g of the filter aid Radiolite (# 700). Chloroform 100 g is poured into and is placed on a ball mill stand and rotated for 5 hours or more to sufficiently dissolve the sample in chloroform. On the other hand, a filter paper (No. 2) with a diameter of 7 cm was placed in the pressure filter, 5.00 g of radiolite was uniformly precoated on it, and a small amount of chloroform was added to bring the filter paper into close contact with the filter. After that, the contents of the container are poured into a filter.
Further, the container is thoroughly washed with 100 ml of chloroform and poured into a filter so that deposits do not remain on the container wall. Then, the upper lid of the filter is closed and filtration is performed. Filtration is performed under a pressure of 4 kg / cm ² or less, and 100 ml of chloroform is added after the outflow of chloroform is stopped.
Is added to wash the residue on the filter paper, and pressure filtration is performed again. After the above operation is completed, all of the filter paper, the residue on it, and the radiolite are placed on an aluminum foil and placed in a vacuum drier, at a temperature of 80 to 100 ° C. and a pressure of 100.
After drying for 10 hours under the condition of mmHg, the total weight a (g) of the dry solid thus obtained is measured, and the chloroform-insoluble content x (% by weight) is determined by the following formula.

[0026]

[Equation 1]

The monomer used for synthesizing the polyester resin preferably used in the present invention is
(A) constitutes a main chain which is a basic skeleton of polyester,
A divalent alcohol monomer and a divalent carboxylic acid monomer,
(B) A trivalent or higher polyhydric alcohol monomer and / or a trivalent or higher polyvalent carboxylic acid monomer, which is involved in the non-linearization of the polyester (formation of a side chain / crosslinked structure), is an essential component. And Further, if necessary, a monomer other than the above (a) and (b) can be used in combination.

Examples of the divalent alcohol monomer in (a) above include polyoxypropylene (2.2)-
2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -bis (4-hydroxyphenyl) ) Propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-
Etherified bisphenols such as bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,
4-butanediol, 1,4-butenediol, neopentyl glycol, 1,5-pentanediol, 1,6
Examples thereof include hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A and hydrogenated bisphenol A.

Examples of the divalent carboxylic acid monomer in the above (a) include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, Sebacic acid, azelaic acid, malonic acid, n-dodecylsuccinic acid,
Examples thereof include n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, and anhydrides or lower alkyl esters of these acids.

Examples of the trihydric or higher polyhydric alcohol monomer in (b) above include sorbitol, 1, 2,
3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol,
1,2,5-pentanetriol, glycerol, 2-
Methylpropanetriol, 2-methyl-1,2,4-
Examples thereof include butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like.

Examples of the trivalent or more polyvalent carboxylic acid monomer in (b) above include 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid,
1,2,4-naphthalenetricarboxylic acid, 1,2,4-
Butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1, Examples thereof include 2,7,8-octanetetracarboxylic acid, pyromellitic acid, empole trimer acid, and anhydrides or lower alkyl esters of these acids.

The method for producing the polyester resin is not particularly limited, but from the viewpoint of controlling the saponification value, the acid value and the proportion of the chloroform insoluble content within a certain range, the polyester resin is produced according to the following conditions. Is preferred.

The polyester resin is 300 KOHmg /
A resin having a saponification value of g or more is preferable, and a resin having a large content of ester bonds is preferable. In order to synthesize such a resin, it is necessary to synthesize it from a monomer having a relatively small molecular weight. The average molecular weight of the monomer is preferably 205 or less, more preferably 16
0 or less.

The polyester resin is 30 KOHm
A resin having an acid value of g / g or more, and in order to synthesize such a resin, in the alcohol monomer and the carboxylic acid monomer, the ratio of the carboxylic acid monomer (the ratio as a functional group) Should be increased. Specifically, the carboxyl group of the carboxylic acid monomer may be 1.0 to 1.4 with respect to 1 hydroxyl group of the alcohol monomer, preferably 1.1 to
A good value is 1.4.

From the viewpoint of controlling the ranges of saponification value and acid value, when the amount of the monomer in the polymerization reaction system decreases due to scattering or sublimation, the polymerization reaction system is sequentially replenished with the monomer corresponding to the decreased amount. It is preferable to carry out the reaction.

The polyester resin is preferably a resin having a chloroform insoluble content of 0.5 to 20% by weight, and the following conditions are preferable for synthesizing such a resin.

The proportion of chloroform-insoluble matter can be controlled by adjusting the cooling rate of the product (polyester) after the termination of the polymerization reaction.

The proportion of the chloroform-insoluble matter can be controlled by adjusting the proportion of the trivalent or higher polyvalent monomer [(ii)]. In order to adjust the ratio of the chloroform insoluble content to the range of 0.5 to 20% by weight,
Although it depends on other synthesis conditions, it is preferable to use the polyvalent monomer having a valence of 3 or more in an amount of 1 to 15 mol%.

This trivalent or higher polyvalent monomer [(b) above]
May be added to the reaction system together with the divalent monomer [(a)] to cause the polymerization reaction, but the linear polyester having a number average molecular weight of about 300 to 1400 may be used depending on the divalent monomer. After synthesizing the above, it is also possible to add a polyvalent monomer having a valence of 3 or more to this system to cause a polymerization reaction between the linear polyester and the polyvalent monomer.

<Electrostatic Image Developing Toner> The toner of the present invention contains at least a binder resin and a colorant, and contains, for example, the above-mentioned polyester resin as the binder resin. As the binder resin constituting the toner, different kinds of resins may be used in combination as needed.

The colorant constituting the toner of the present invention is not particularly limited, and conventionally known dyes, pigments and the like can be mentioned.

Specifically, for example, carbon black, nigrosine dye (CI. No. 50415B), aniline blue (CI. No. 50405), chalco oil blue (CI. No. azoic Blue 3). ,
Chrome Yellow (CI No. 14090), Ultramarine Blue (CI No. 77103), Dupont Oil Red (CI. No. 26105), Quinoline Yellow (CI. No. 47005), Methylene blue chloride (CI No. 52015), phthalocyanine blue (CI. No. 74160), malachite green (CI. No. 42000), lamp black (CI. No. 77266), Rose Bengal (CI No. 45435), mixtures thereof, and others. The mixing ratio of the colorant is preferably 1 to 20 parts by weight based on 100 parts by weight of the binder resin.

The toner of the present invention may contain other additives, if necessary. As such an additive, a low molecular weight polyolefin such as a low molecular weight polyethylene or a low molecular weight polypropylene can be preferably used, and a softening point by the ring and ball method of 70 to 150 ° C. is particularly preferable, and a low molecular weight polyolefin of 120 to 150 ° C. is more preferable. It can be preferably used.

Further, when the low molecular weight polyolefin is added, the toner of the present invention is further improved in offset resistance and its productivity (grindability of toner raw material).

The content of the low molecular weight polyolefin is usually preferably 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

The particle size of the toner of the present invention is arbitrary, but a toner having a small particle size is likely to exhibit the effects of the present invention, and the volume average particle size is 2
It is preferably ˜12 μm, and particularly preferably 3 to 9 μm.

Further, from the viewpoint of further increasing the charging speed and further improving the charging characteristics, it is preferable that the toner of the present invention is externally added with inorganic fine particles.

As such inorganic fine particles, those having a number average primary particle diameter of 5 to 40 nm are preferable. The specific surface area of the inorganic fine particles measured by the BET method is 40 to 200 m ² /
g is preferable. The mixing ratio of the inorganic fine particles is preferably 0.1 to 1.0% by weight of the whole toner.

Examples of the constituent material of the inorganic fine particles include silica, alumina, titanium oxide and the like. Among these, silica fine particles are preferable, and silica fine particles whose surface is hydrophobized are particularly preferable.

As an example of the method for producing the toner of the present invention, a binder resin containing the above-mentioned polyester resin, a colorant, a low molecular weight polyolefin, and other various additives which are added as necessary are added. Premixing, melt-kneading, cooling, coarse pulverization, fine pulverization of this mixed system, and then classification are performed to obtain a toner in the form of particle powder having a desired particle diameter.

<Carrier> The toner of the present invention is mixed with a carrier and used as a two-component developer.

As the carrier constituting the two-component developer, an uncoated carrier composed only of magnetic particles such as iron, ferrite and magnetite, a resin coated carrier in which the surfaces of the magnetic particles are coated with a resin, or a magnetic fine particle is a resin or the like. Any of the carriers dispersed in can be used.

The particle size of the carrier is 20 to 20 in terms of volume average particle size.
150 μm is preferred. When the surface of the magnetic particles is coated with a resin or the like, the resin is not particularly limited, but for example, styrene-acrylic resin, silicone resin,
Fluorine resins and the like are often used.

<Image Forming Method and Apparatus> An image forming method using the developing method and apparatus of the present invention will be described below with reference to the sectional view of the analog type image forming apparatus shown in FIG. The image forming method of the present invention is not limited to this, and can be applied to general electrophotographic devices such as digital copiers, LED printers, and liquid crystal shutter printers. , Printing, facsimile, etc.

In FIG. 1, reference numeral 10 denotes an organic photosensitive drum, which is rotationally driven in the direction of the arrow (clockwise), and is uniformly charged by a charger 11.
2, an image is exposed to form an electrostatic latent image.

In the image exposure means 12, an image exposure obtained by optically scanning an original by an original scanning optical system (not shown) is applied on the photosensitive drum 10 to form the electrostatic latent image.

The electrostatic latent image is magnetically brush-developed by the developing device 13 to form a toner image. Here, the developing device 13
Is filled with a two-component developer composed of a non-magnetic toner and a magnetic carrier, and after being stirred and mixed by the screws 131 and 132 and the stirring blade 133, the outer circumference of the magnet 135 is rotated by a sleeve 134 in the direction of the arrow. The magnetic brush is adhered and conveyed to form a magnetic brush, and the electrostatic latent image is developed by the magnetic brush.

Reference numeral 23 denotes a sensor which detects the toner density control based on the change in the magnetic permeability of the developer and outputs an electric signal corresponding to the change. The toner is replenished from a toner replenishing device (not shown) in accordance with the signal. A humidity sensor 24 is placed at a position away from the fixing device 20 and measures the humidity of the outside air. The toner image is made to be easily transferred by the PTL 14, and then transferred onto the transfer material P which is conveyed by the timing rollers 17 and 18 at the same timing.
It is transferred by the action of 5 and separated by the separation electrode (separator) 16.

The transfer material P separated by the separation pole 16 and the separation claw 181 is conveyed by the conveyor belt 19 to the fixing device 20, and the toner image is thermally fixed on the transfer material P. After the transfer, the photoconductor drum 10 is cleaned by a cleaning device (cleaning device) 21, and is neutralized by the pre-charging static elimination lamp PCL22 to prepare for the next image formation.

In the cleaning device 21, the transfer residual toner on the photosensitive drum 10 is cleaned by the guide roller 212 and the cleaning blade 211, and the cleaned toner is cleaned by the guide roller 212.
Then, the toner is fed into the unloading screw 214 via the guide plate 213, and is discharged to the external toner receiver by the unloading screw.

[0061]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

(Preparation of Toner) Polymerizable monomer neopentyl glycol 28.6 mol%, ethylene glycol 1
9.1 mol%, terephthalic acid 45.2 mol%, anhydrous 1,
A polyester resin was prepared using 7.1 mol% of 2,4-benzenetricarboxylic acid. Its acid value is 70
(KOHmg / g), saponification value 530 (KOHmg / g)
g), the softening point was 146 ° C, the glass transition temperature was 69 ° C, and the chloroform-insoluble content was 2%.

100 parts by weight of the above polyester, 8 parts by weight of Black Pearls L (manufactured by Cabot), and purified carnauba wax No. After mixing 2 parts by weight of No. 1 (manufactured by Noda Wax Co.) and 2 parts by weight of Hoechst Wax C (manufactured by Hoechst Co.), the mixture was melt-kneaded by a twin-screw extruder, cooled, and then coarsely ground by a hammer mill. Then, the mixture was finely pulverized with a Kryptron (manufactured by Kawasaki Heavy Industries, Ltd.) and classified with a Microplex to obtain colored particles having a volume average particle size of 8.5 μm. Aer
0.6 parts by weight of osil R-805 (manufactured by Aerosil), 0 parts of Aerosil T-805 (manufactured by Aerosil).
Add 8 parts by weight and use a Henschel mixer with a peripheral speed of 40 m
/ S for 20 minutes to produce the toner of the present invention.
The characteristics of the obtained toner are as follows.
In terms of% by weight, the moisture adsorption rate was 0.5% by weight / hour, and the softening point was 121 ° C. (at a moisture content of 1.0% by weight).

(Preparation of Carrier) Cyclohexylmethacrylate (CHMA) / Methylmethacrylate (M
MA) = A copper / zinc ferrite carrier with a weight average particle diameter of 60 μm coated with a copolymer resin of 5/5 was prepared.

(Actual copying test) The carrier and the toner were added at a ratio of 6 parts by weight of the toner to 94 parts by weight of the carrier and mixed in a mixer at room temperature for 20 minutes, and then a mesh opening 10 was obtained.
A developer was prepared by sieving with a 6 μm sieve. 1 using Konica 7050 manufactured by Konica Corporation using the obtained developer
After making 30,000 copies in an atmosphere of 0 ° C and 20% RH, 30
Performed a 30,000 copy test in an atmosphere of ℃ and 80% RH,
Table 1 shows the results of evaluation of image density, fog density, and resolution by performing image sampling. Further, the developer was sampled to measure the toner concentration in the developer. The results are shown in FIG.

<Image Density> The relative density of a solid image having a document density of 1.38 with respect to a copied image was measured by a Macbeth densitometer and used as an image density.

<Fog Density> The relative density of a white background portion having a document density of 0.000 with respect to a copied image was measured with a Macbeth densitometer and defined as a fog density.

<< Resolution >> A pattern consisting of five fine lines having the same line width and spacing is used in 2.8, 3.2, and 1 mm intervals.
3.6, 4.0, 4.5, 5.0, 5.6, 6.3,
7.1, 8.0 original images were copied, and the obtained copied images were observed with a magnifying glass at a magnification of 10 times. The number of images (lines / mm) in which fine lines were clearly separated was solved. It was considered as an image.

In Example 1, the humidity sensor was used for control. That is, when the outside air humidity is 70% RH or higher, the toner concentration control is performed from the target control level of 6% to 5.5.
%, The control voltage is changed to 7.
Changed from 0V to 6.8V. The second embodiment does not perform such control.

[0070]

[Table 1]

The developer of the present invention exhibits some characteristics as shown in FIG. 2 even under extremely severe conditions as described above (no control in FIG. 2). However, it can be seen that even better results can be obtained by controlling the toner concentration with a sensor that outputs an electric signal according to a change in the magnetic permeability of the developer and controlling the output of this sensor according to a change in humidity.

[0072]

According to the present invention, it has excellent charging characteristics,
It is possible to provide an electrostatic image developer capable of obtaining a stable maximum image density, having a low fog and a high resolution, good low-temperature fixability, and excellent in fixing offset resistance, and a developing method and apparatus using the same. I can.

[Brief description of drawings]

FIG. 1 is a sectional view of an image forming apparatus using an electrostatic charge image developing method and apparatus according to the present invention.

FIG. 2 is a diagram showing a change in toner concentration during a copy test.

[Explanation of symbols]

 10 Photoreceptor Drum 13 Developers 131, 132 Screw 23 Toner Density Control Sensor 24 Humidity Sensor

Claims (3)

[Claims] 1. In an electrostatic charge image developer containing an electrostatic charge image developing toner and a carrier, the saturated moisture adsorption amount of the toner is 1.0% by weight or more, and the moisture adsorption rate is (0.2% by weight / (Time) or more, an electrostatic image developer. 2. An electrostatic image developer containing a toner for developing an electrostatic image and a carrier is used, and the density of the toner is controlled by a sensor which outputs an electric signal according to a change in magnetic permeability of the developer. In an electrostatic charge image developing method in which an electrostatic latent image is visualized while controlling the output of this sensor according to a change in humidity, a saturated moisture adsorption amount of the toner is 1.0% by weight or more, and a moisture adsorption rate is Is (0.2% by weight / hour) or more. 3. An electrostatic image developer containing a toner for developing an electrostatic image and a carrier is used, and the density of the toner is controlled by a sensor which outputs an electric signal according to a change in magnetic permeability of the developer. In an electrostatic charge image developing device that visualizes an electrostatic latent image while controlling the output of this sensor in accordance with changes in humidity, the saturated moisture adsorption amount of the toner is 1.0% by weight or more, and the moisture adsorption speed is Is (0.2% by weight / hour) or more.