JPS6252563A - Developer - Google Patents

Abstract

PURPOSE:To provide a developer which exhibits a stable frictional electrostatic chargeability even after long-period use or in the special environment of high temp. and high humidity or low temp. and low humidity by specifying the frictional electrostatic charge quantity of a positive chargeability toner and the frictional charge quantity of a mixture composed of the positive chargeability toner and pulverous silica powder. CONSTITUTION:This developer consists of the positive chargeability toner and positive chargeability pulverous silica powder. The frictional charge quantity TA of the toner is TA>=+20muC/g and the frictional charge quantity of the mixture composed of the toner and the pulverous silica powder, when designated as TB is 1<=TA/TB<=3, more preferably, 1.2<=TA/TB<=2. The decrease of the electric charge of the developer and the deterioration of the image are obviated even after repetition of copying for a long-period of time by using the positive chargeability toner and the positive chargeability pulverous silica powder based on the above-mentioned material structure. Always the good image is thus formed and since the stable electrostatic chargeability is exhibited even in the special environment of high temp. and high humidity or low temp. and low humidity, the stable image is shown despite various environmental fluctuations.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer used in electrophotography, electrostatic printing, and the like. More specifically, the present invention relates to a developer containing a non-magnetic, positively charged toner that does not contain a magnetic substance such as magnetite and is made essentially only of an organic substance.

[Prior Art] Conventionally, methods such as cascade h1 and powder-cloud method are known for developing non-magnetic toner in electrophotography, but in general, non-magnetic toner is efficiently transferred to the developing section. In order to transport it, a method is used in which it is mixed with magnetic particles such as iron powder or ferrite powder.

As one example, mixing toner and magnetic particles,
A widely known method is to form a magnetic brush and develop an electrostatic charge image by rubbing.

Still another developing method includes a developer container for storing toner and magnetic particles for toner application, a toner carrier for conveying the toner to a latent image carrier, and a toner outlet from the developer container described in +ij [1]. 1111 A thin layer of toner is formed on the toner carrier by placing a magnet forming a magnetic brush made of magnetic particles for toner coating in contact with the toner carrier on the L flow side, and applying a thin layer of toner to the toner carrier. Instead, there is a method in which the gap between the toner carrier and the electrostatic image holder is set to a large value and the electrostatic image is developed.

In these methods, substantially non-magnetic toner is uniformly mixed with magnetic particles in the developing section! E, or a state of uniform and thin coating on a carrier must be maintained, and the forces to achieve this state are mainly dominated by electroelectric attraction and physical attachment. That is, it is necessary to precisely control the amount of electrostatic charge and triboelectric charging ability of the toner.

However, if the amount of charge of the toner is uniformly controlled,
Moreover, it is extremely difficult to stabilize the amount of charge even after repeated copying over a long period of time or under special environments of high temperature, high humidity, and low temperature and low humidity. Particularly in positively chargeable toners, resins and pigments are the constituent elements of the toner.

It is very difficult to uniformly charge fluidizers, abrasives, lubricants, etc. to +E, and it is not clear what the material composition related to charging should be for a positively chargeable toner.

IFi1 Problem A to be Solved by the Invention The object of the present invention is to provide an IIE chargeable toner that solves the problems mentioned above.
Our objective is to provide a toner that has an ideal material composition as an iE chargeable toner and exhibits stable JTF rub, lip, and lli properties even after long-term use and under special environments of high temperature, high humidity, and low temperature and low humidity. .

Means and actions for solving the L problem] i.e. unoccurred 11
is characterized in that at least the positively charged toner is made of iE-chargeable silicic acid fine powder, the friction da, 'F'il amount TA of the toner is T^≧+20Cog, and the toner and the silicic acid fine powder are 1≦T^/To≦3. Preferably 1.2≦T^/T
The developer satisfies o≦2.

Here, toner refers to particles obtained by kneading, crushing, classifying, melting, spraying (minute P!I) granulation, or polymerization granulation of raw materials, and the subsequent Superplasticizer/
This differs from the form of a developer that is practically sealed by mixing particles with a charge control agent.

As a result of intensive research, the present inventors have discovered that one of the major causes of fluctuations in the charging ability of developers after long-term copying or under special environments of high temperature, high humidity, and low temperature and low humidity is that fluidity improvers or charge control agents are used as fluidity improvers or charge control agents. It was confirmed that there are state-based changes in the silicic acid fine powder added to the toner; qualitative changes due to moisture absorption and drying. Furthermore, the present inventors studied the structure related to charging between the toner and the silicic acid fine powder, and found that the toner has a certain large charging ability, and the silicic acid fine powder would rather play a role in suppressing the electric charge. It was confirmed that the chargeability was stable as a whole, and it was found that satisfying the conditions as described in J.2 is an extremely favorable material composition for a positively chargeable developer.

The toner of the present invention can be manufactured by containing a conventionally known positively chargeable substance, and in particular, a styrene copolymer containing 1 to 15i% of aminoacrylic compound at 50 miM. ($) The one that includes J2 is a big friction;? As the aminoacrylic monomer, which is most preferable because it has an electric power, all conventionally known aminoacrylic monomers can be used, but those represented by the above structural formula are generally effective.

R1 is hydrogen or a methyl group or an ethyl group R2 is a fullkylene group having 1 to 4 carbon atoms lh, Rs C3R is an alkyl group having 1 to 4 prime numbers Constituent components other than aminoagril of the cotama combination are conventionally known lti GS, you can use all of your body, but -
・Generally, styrene-acrylic co-ed: I\ body is 70i
It is desirable that the styrenic monomer contains styrene, vinyltoluene, α-methylstyrene, etc., and the acrylic monomer includes acrylic acid, methyl ethyl acrylate, etc. propyl butyl
2-Ethylhexyl esters, methacrylic acid, methyl, ethyl, propyl, butyl, 2-ethyl methacrylic acid
Examples include esters of hexyl. All conventionally known methods can be used to polymerize the copolymer, but homogeneous systems such as bulk polymerization and solution Togane are particularly preferred.

As the silicic acid fine powder used in the present invention, any powder that satisfies the conditions described above can be used, such as ``fluctuating the amount of triboelectric charge caused by mixing with the toner.'' However, it is desirable that the silicic acid fine powder does not disturb the toner's (ip) concentration as much as possible. Therefore, it is correct in itself;
Silicic acid fine powder having t2 conductivity 1 For example, silicic acid fine powder subjected to a coupling treatment with an aminoalkylsilane compound or a treatment with a silicone oil having an amine in its side chain is preferable, and among them, a fine silicic acid powder having an amine in its side chain is preferable. Silicic acid fine powder treated with silicone oil is most preferable from the viewpoint of environmental stability. As the base material for the silicic acid fine powder, silicic acid fine powder produced by a dry method or a wet method can be used.

Here, the 51-dry method is a method for producing fine silica powder produced by vapor phase oxidation of a silicon halide compound. For example, a method that utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas during oxyhydrogen heating.

(The basic reaction formula is as follows.

SiC! ! s + 2 H2+ 02→SiO2+ 4
It is also possible to obtain a composite fine powder of silica and other total oxides by using HCl or other metal halide compounds such as aluminum chloride or titanium chloride together with a silicon halide compound in this production process.
These are also included.

The 110 temporary silica fine powder produced by 1q gas phase oxidation of a silicon halide compound used in the present invention is as follows:
For example, some products are commercially available under the following trade names.

AEROSIL +30 (11 pieces Aerosil) 200 x50 Te0O 0X80 0X170 0K84 Ca-0-SiL M-5 (CA
BOT Co, Ltd.)ll5-7S-7
5 S-5 H-5 Wacker HDK N 20V
15 (WACKER-C: HEMIE 0888 company)
N20ED-CFine 5ilica (Dow Corning Co., Inc.) Fransol (Fransi1 Inc.) On the other hand, various conventionally known methods can be applied to the method of producing the silicic acid fine powder used in the present invention by a wet method.

For example, the decomposition of sodium silicate by acid, ・If shown in the general reaction formula (the reaction formula is omitted below), Na2O・XSiO2+HC1+H70+5i07・
nH2O+Nac1 and other decomposition of sodium silicate with ammonia salts or alkali salts, after producing alkaline earth metal silicate from sodium silicate,
There are methods such as decomposing with acid to produce silicic acid, using ion exchange resin to produce silicic acid from sodium silicate base liquid, and using natural silicic acid or silicate.

The silicic acid fine powder mentioned here can be any of anhydrous silicon monoxide (silica) and other silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate. .

Commercially available fine silicic acid powders synthesized by a wet method include those sold under the following trade names, for example.

Carplex k4A field, x 5J medicine 21 pseal 11 bottles silica toxyl,
Fine Seal Tokuyama i'f Tatsuvitaseal
Multi-wood fertilizer Jiruton, Silnenx Mizusawa Kagaku Starsil Kamijima Kagaku Himezil
Aihime Pharmaceutical Thyroid
Tomi Davison Chemical Formerly-5il (Hiseal) Pittsburgh Plate GIass, Co
.

(Pittsburgh Plate Glass) Durosil Fiillstoff-GesellschaftUl
torasil (Ultra Seal) Marquard (
7 Uerstotzf 0 Gesellschaft Mark Orth) Manosil (Manonur) Hardman and Ho1den (Hartman at Holden) HOeSCh (Hensch) Che IIlische Fabrik ) loeSc
h K-G (Hiemi 7che Fabrikhensch) Sit-Stone (Silus)-7) Stone
r Rubber Ca.

(Stoner Lover) Nalca (Nalml) Na1co Chew
, Go.

(Narco Chemical) Quso Ph1ladelphia
Quartz Go.

(Philadelphia Quartz) Santocell (Santocell) Monsant
o, (:chemical Go.

(Monsando Chemical) fsil (Imusil) Illinois SMin
erals Co.

(Illinois Mineral) Calciua+ 5ilikat (Calcium
Silicato) Chellische FabrikHoe
sch, ni-G (Hiemisch Verprikhensch) Galsil (Kargil) Fiillstoff-GesellschaftMa
rquart (Fürstoffgesellschaft Markorth) Fortafil (7*Lutafil) IIIperi
al Chemical Industries.

ttd, (Imperial Chemical Industries) Microcal Joseph Crosfields & 5on
s, Ltd.

(Joseph Crossfield and Thump) Manosil (7 Nosil) Hardman and Halden (Hardman
Ant Holden) Vulkasil Farbenfabriken Bryer, A, -
G.

(Falpenfabriken Purya) Tufknit (tough knit) Urham Chemicals, Ltd.

(Doulham Chemicals) Silmoth White Stone [Ko Star Lenx Kamishima Chemical Fricosil Poly Wooden IIP! J: Among the silicic acid fine powders, the specific surface area due to nitrogen adsorption measured by the BET method is 30 m'/g or more (especially 50 to 400 ta'
/g) loses good results.

1. Adding 43 amines to the side chains used in the treatment of the silicic acid fine powder
The silicone oil that can be used is generally expressed by the formula (1): 1 &, ? Silicone oils containing the l'-position can be used.

5i-0- R2... (0 type (Here, R1 is hydrogen, alkyl, (, aryl group.

or represents an alkoxy group, R7 represents alkylene, cyphenylene, and R3 and Ra represent hydrogen, an alkyl group, or an aryl group, provided that the alkyl group, aryl group, alkylene group, or phenylene group in 1- contains an amine. Alternatively, halogen or the like may be substituted within a range that does not impair chargeability, or 1: may be substituted. ) As the silicone oil having an amine in the side chain of the reprint, for example, there is an amino-modified silicone oil represented by the following structural formula 5, which is preferable. , R2 represents an alkylene group, a phenylene group, or an alkyl group containing an amine; R3 represents hydrogen, an alkyl group, or an aryl group; m and n are numbers of 1 or less; Specifically, the following are preferred, and these may be used alone or in a mixed system of two or more.

KF393 (manufactured by Shin-Etsu Chemical) Go
3EiOKF857 (manufactured by Shin-Etsu Chemical)
70 830KF8130 (manufactured by Shin-Etsu Chemical) 250 7HOKF8Eil (manufactured by Shin-Etsu Chemical) 3500 2000KF8B
2 (manufactured by Shin-Etsu Chemical) 750 190
0KF884 (manufactured by Shin-Etsu Chemical) 1700
3800KF865 (manufactured by Shin-Etsu Chemical)
90 4400KF3f+9 (manufactured by Shin-Etsu Chemical) 20 320KF383 (manufactured by Shin-Etsu Chemical) 20 320X-22-3
880 (manufactured by Shin-Etsu Chemical) 90 8800X-
22-3800 (manufactured by Shin-Etsu Chemical) 2300 3
800X-22-380IC (manufactured by Shin-Etsu Chemical) 35
00 3800X-22-3810B (manufactured by Shin-Etsu Chemical) 1300 1700 J1 per amine
1 means tiF”, l, (g/eqi
v), molecules -+, + per molecule. A57. ) is the number ・1x t+/i.

In the present invention, the processing amount of silicone oil having an amine in the side chain is 0.2 of the total treated silicic acid fine powder jI (
~70 weight percent in developer 0.0001-10
It is preferable to set the amount to be % i.

Furthermore, the appropriate amount of silicone oil having an amine in the side chain to be treated is determined by using the following formula: When the specific surface area of the silicic acid fine powder is b112/g and the amine value of the silicone oil having an amine in the side chain is a, particularly good results are obtained when the relationship of formula (■) is satisfied.

The silicone oil becomes in excess of the silicic acid fine powder, causing problems such as leaching of the silicone oil having an amine in the side chain from the silicic acid fine powder, but it is insufficient and the purpose of the present invention cannot be achieved. It becomes difficult.

・25℃ of silicone oil with amine in the side chain
The viscosity at
00 cps or less is preferable. If the viscosity is 50 QOcps or more, the silicone oil having an amine in its side chain will not be sufficiently dispersed in the silicic acid fine powder, which may easily cause poor images such as fog.

1- The treatment of fine silicic acid powder with a silicone oil having an amine in its side chain can be carried out, for example, as follows. Vigorously stir the silicic acid fine powder while heating if necessary, and then spray or vaporize silicone oil containing amine or its solution onto the L side button, or spray the silicic acid fine powder on the L side button. The treatment can be easily carried out by making a slurry and adding a silicone oil having an amine in its side chain or a solution thereof while stirring the slurry.

In the present invention, one type or a mixture of two or more of the silicone oils having amines in the side chains mentioned above may be used.

In addition, the applied charge of these treated silicic acid fine powders may be set so that the ratio TA of the amount of triboelectric charge satisfies the condition described in L, but in general, 0 to 100 parts by weight of toner is used.
．． The effect is exhibited when O is added in an amount of 1 to 3 parts by volume, and particularly preferably when it is added in an amount of 0.03 to 1.5 parts by weight, it exhibits positive chargeability with excellent stability.

Also, K-P! used in the present invention! #The fine powder may be further treated with a conventionally known hydrophobizing agent if necessary, and a known method may be used to treat the fine powder, such as an organosilicon compound that reacts with or physically adsorbs to the fine silicic acid powder. Attachment 17 is achieved by chemical treatment.

Examples of such organosilicon compounds are hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane,
Allyl phenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, silylmercaptan, triorganosilylacrylate, Vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilano, diphenyljethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and per molecule Examples include dimethylborisloyasan, which has 2 to 12 siloxane molecules and each terminal unit has one hydroxyl group bonded to 81. These may be used alone or in a mixture of two or more.

In the present invention, it is possible to add other resins, polymers, etc. to the toner in addition to the copolymer described in L. Examples include polystyrene, styrenic copolymers such as polystyrene-butadiene copolymers, styrene-acrylic copolymers, and polyethylene.

Ethylene copolymers such as polyethylene vinyl acetate copolymer, polyethylene vinyl alcohol copolymer, phenolic resin, and epoxy resin. Allyl phthalate resin, polyamide resin. These include polyester resin, maleic acid resin, etc. Furthermore, there are no particular restrictions on the manufacturing method of any of the resins.

As the coloring material used in the toner of the present invention, conventionally known coloring materials such as carbon black, dyes, and pigments can be used.

It is also possible to add other lubricants, abrasives, etc. to the toner.

Further, the structure of the present invention is applied to a microcapsule toner,
It is also possible to implement the core material or the shell material or both.

Next, a method for measuring the amount of triboelectric charge in the present invention will be described.

FIG. 3 is an explanatory diagram of the frictional charge amount measuring device.

A metal measuring container 12 with a conductive screen 13 of 400 meshes (can be changed as appropriate to a size that does not allow magnetic particles to pass through) on the bottom contains the toner or toner constituent fine particles whose triboelectric charge amount is to be measured, and 200 to 200 mesh particles. Irregular iron powder with a particle size between 300 mesh (11 iron powder EFV200/300
, the surface of which is untreated and similar to the toner carrier, is filled with about 4 g of a mixture (developer) with a charge ratio of 1:9 (substantially no triboelectric charge) and covered with a metal lid 14. Let % WH of the entire measurement container 2 at that time be 1 (g). Next, in the suction @11 (the part in contact with the measurement container 2 is at least an insulator), the suction air from the suction [117 Adjust the control valve 16 to set the pressure of the vacuum gauge 15 to 70+smHg.
Suppose that In this state, suction is applied sufficiently (for about 1 minute) to remove the toner or the mixture of toner and fine silicic acid powder. The potential of the electrometer 19 at this time is assumed to be V (volt).

Here, 18 is a capacitor whose capacity hi is C (gF), and the amount of electricity in the entire measurement container after suction is measured W? (
g), this frictional electrification = r (q/g) is calculated as in the equation.

However, the a11 constant conditions are 23° C. and 50% RH.

[Example] Specific examples will be described below. In addition, all copies and percentages are per-unit sales.

Example 1 Styrene-butyl methacrylate-diethylaminoethyl methacrylate 95 parts rate copolymer (80:17:3) phthalocyanine pigment
5 parts were kneaded, crushed and classified to obtain a toner with a full uniform particle size.

Frictional charging 4′LT^=35.3 Cog.

On the other hand, 100 parts by weight of silicic acid fine powder synthesized by a dry method (trade name, Aerosil TT3O. specific surface area approximately 130 m2/g, manufactured by Aerosil) was stirred and maintained at a temperature of approximately 250°C to add amines to the side chains. silicone oil (viscosity 70 cps at 25°C, per amine;
H830) 20 modified, +7 was sprayed and treated for 10 minutes.

100 parts by weight of the blue toner was mixed with 0.0 parts by weight of silicic acid fine powder treated with a silicone oil having an amine attached to the side chain of 1-.
8 parts by weight were added. Hikosuri electrification of the mixture 7MT8=
It was 22.8μCog, and T/Tn=1.8, which satisfied the conditions of the present invention.

6 parts of a mixture of this toner and silicic acid fine powder and a particle size of 30
Mix with 100 parts of unshaped iron powder of 0 to 400 mesh,
When the developer was obtained and put into a Canon MP-5000 copying machine which had a resolution capable of forming a negative latent image and an image was produced, a clear image without capri was obtained, and the image reflection density was 1. It was .41. Further, in order to examine the durability of the developer, a durability test of 10,000 sheets was carried out, and a clear image (image density 1.38) with no fog, similar to the initial image, was obtained. On the other hand, a high temperature and high humidity environment (30℃, 80%RH)
When I performed the image output in the same way in the same way, the image density was 1.2.
No. 8, an image without any problem of fogging was obtained. Furthermore, clear and fog-free images were obtained even under a low temperature and low humidity environment (10° C., 10%).

Comparative Example 1 3.5% of the silicic acid fine powder of Example 1 was added to the toner of Example 1.
% addition, Tn = 11.7gC/g.

T^/To = 3.8, which did not satisfy the conditions of the present invention.

When the same test as in Example 1 was carried out using this toner, as the number of copies increased, the images became worse with capri. Also, in low temperature and low humidity environments, the image became pale.

Example 2 FIG. 1 is another example of the embodiment. In the figure, 1 is an electrostatic image carrier, 2 is a toner carrier, 5 is a developer, 43 is a developer, 48 is a magnetic roller, 49 is a non-magnetic sleeve thereof, 50 is a magnet, 52 is a magnetic brush, 53
indicates a one-component developer or a mixture of a developer and magnetic particles.By magnetically holding a magnetic carrier in a non-magnetic sleeve 49 to form a brush and rotating the sleeve 49, toner or developer 53 is 1- A uniform one-component developer layer 5 is formed by drawing up the toner with a carrier brush and applying the toner in contact with the toner carrier 21 . At that time, since the magnetic particles are held on the magnetic roller 48 by magnetic force, they do not transfer to the toner carrier 2F.
The image is developed by flying from L to the streetcar image holder L. magnetic roller 4
The gap between 8 and the toner carrier 2 is adjusted so that the thickness of the one-component developer layer on the toner carrier 2 is about 5 to 100 mm.

The gap between the toner carrier 2 and the electrostatic image carrier 1 may be made larger than the thickness of the one-component developer layer, and a developing bias voltage may be applied to the toner carrier 2.

Here, when a toner with an average particle size of t2g consisting of 7 parts of rhodamine pigment was obtained, T^=
It was 22.0 (μCog).

100 parts of this toner and 1.0 parts of the silicic acid fine powder of Example 1
part was mixed. TB=18.3 pG/g, Topa=1.2.

10 parts of a mixture of this toner and silicic acid fine powder and Example 1
The gap between the toner carrier 2 and the magnetic roller 48 is approximately 2ffi layer, and the magnetic brush 5 is mixed with 100 parts of iron powder carrier.
The toner layer of about 80 g was placed in the developing device shown in Fig. 1, which was set to have a maximum J of about 3 mm. The roller L forms an AC waveform with a frequency of 200.
Peak value of Hz voltage ±450 V and DC component -250 ■
and the peak voltage value -700V and +200V7
When the image was developed using a 1t copy machine manufactured by Canon Co., Ltd. (PC-20), good results similar to those of Example 1 were obtained.

Example 3 FIG. 2 is a diagram showing another example of the embodiment.

In the figure, 1 is an electrostatic image carrier, 2 is a toner carrier, and 3 is a toner carrier.
is a hopper, 6 is a bias power supply for development, 5 is a one-component developer, 50 is a fixed magnet, 52 is a magnetic brush made of a mixture of magnetic particles and toner, and 58 is a blade for regulating toner thickness, which is formed on the toner carrier 2L. The magnetic brush 52 is circulated by rotating the toner carrier 2, takes in the silica externally added toner in the hopper 3, and uniformly coats the toner carrier 2 with a thin layer. Next, the toner carrier 2 and the electrostatic image carrier 1 are placed in opposition with a gap greater than the thickness of the toner layer, and the toner 5 on the toner carrier 2F is developed by flying onto the electrostatic charge image on the electrostatic image carrier 1). The thickness of the toner layer is magnetic brush 5.
2, that is, the amount of carrier and the regulating blade 58. The gap between the electrostatic image carrier 1 and the toner carrier 2 may be made larger than the thickness of the toner, and a developing bias may be applied from the bias power source 6.

Here, the mixture 20 of the toner of Example 1 and silicic acid fine powder
g to f iron powder particles -20g1! l-mix and distribute the mixture so that the gap between the regulating blade 58 and the toner carrier 2 is approximately 25 mm.
The image was placed in the developing device shown in Fig. 5, which was set to have zero extension, and the gap between the developing roller and the electrostatic image holder was maintained at 300 μ.
A single layer of toner with a length of approximately 80 mm was formed on the developing roller 2, and the peak value of the voltage at a frequency of 200 Hz was ±450 V as an AC waveform.
By adding a DC component of 250V to the peak value of electric tf -70
Similar good results were obtained when developing at 0V and +200V.

Comparative Example 2 Styrene-butyl methacrylate copolymer (85:15) eEi part Nigrosine dye 2 parts Carbon black 4 parts Average particle size 10. toner (100 copies).

To 100 parts (= 17.5 final G/g), 0.0 parts of silicic acid fine powder with a specific surface area of about 90 m2/H synthesized by a wet method was added.
When mixed with 4 parts, T port = 12.1 final Cog,
TA/TB=1.4. When the same test as in Example 3 was conducted using this toner, the resulting images were extremely pale after several dozen copies, and this tendency was noticeable at high temperatures and high humidity.

[Effects of the Invention] Positive IF conductive toner and i' based on the material structure of the present invention
E? ii' By using electrically conductive silicic acid fine powder, the charge of the developer decreases even after repeated copying over a long period of time, and images do not deteriorate, making it possible to always provide good images. . Furthermore, since the toner exhibits stable charging ability even under special environments such as high temperature and high humidity, and low temperature and low humidity, it was able to provide stable images even under various environmental changes.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views showing different forms of the developing device used to carry out the developing method according to the present invention. FIG. 3 is an explanatory diagram of a measuring device for frictional electrification j13 according to the present invention. l... Electrostatic image holder 2... Toner carrier 3.
··hopper

Claims (1)

[Claims] Consisting of at least a positively charged toner and positively charged silicic acid fine powder, the positively charged toner has a triboelectric charge amount T_A of T_A.
≧+20 μC/g, and 1≦T_A/T_B≦3, where T_B is the amount of triboelectric charge of the mixture of the positively charged toner and the silicic acid fine powder.