JPH0247670A - Electrophotographic image forming method - Google Patents

Abstract

PURPOSE:To prolong the life of a developer and the maintenance cycle of a fixing device by incorporating fine inorg. particles having pH >=7.0 into the developer and providing a resin coating layer dispersedly contg. metal coated fillers as the surface layer of a heat roller, then grounding this layer. CONSTITUTION:The fine inorg. particles having pH >=7.0 are incorporated into the developer and the resin coating layer 13 dispersedly contg. the metal coated fillers is provided as the surface layer of the roller 1 used for fixing with the heat roller; in addition, the layer 13 is grounded. The rise of the triboelectrostatic charge of the toner is improved in this way and the stable positive triboelectrostatic charge over a long period of time and the good transfer characteristic in high-temp. high-moisture environment are maintained. The electrostatic adhesive power of the toner to the fixing rolls 1, 2 is decreased and the exchange cycle of the fixing cleaning roll is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to electrophotographic copying, and more particularly to a developer for forming a copied image and fixing of the copied image.

[Prior art]

As a method for forming an image from information to be visualized, methods using electrostatic latent images, such as electrophotography, electrostatic recording, and electrostatic printing, are widely used.

For example, in electrophotography, a latent image carrier provided with a photosensitive layer made of a photoconductive material is given a static charge of -, and then image exposure corresponding to the original image is applied to the surface of the latent image carrier. A corresponding electrostatic latent image is formed, and this electrostatic latent image is developed with a developer to form a toner image. This toner image is transferred to a recording material such as paper and then fixed by heating, pressure, etc. to form a copy image. On the other hand, after the transfer step, the latent image carrier is neutralized, and then the toner remaining on the latent image carrier without being transferred is cleaned, and the toner is used for forming the next copy image.

Furthermore, in order to stably form high-quality, fog-free copied images over a large number of times, it is required that the triboelectric charging properties of the toner be maintained stably.

An example of a developer used in electrophotography is an electrostatic image developer composed of toner particles containing polyester as a binder resin, inorganic fine particles made of negatively charged silica fine particles, and a fluororesin-coated carrier. (Unexamined Japanese Patent Publication No. 6
0-176052), or composed of toner particles containing polyester as a binder resin, positively chargeable non-@ fine particles made of alumina fine particles, titanium oxide fine particles, nitrogen-containing silica fine particles, etc., and a fluororesin-coated carrier. electrostatic image developer (Japanese Patent Application Laid-Open No. 62-229158
No.) etc. are known.

However, in the technique disclosed in JP-A-60-176052 that uses a combination of negatively chargeable silica fine particles and a fluorine-based resin coated carrier with strong negative chargeability, the triboelectricity of the toner particles rises poorly, and the number of copies is As the amount increases, toner scatters in the developing section, contaminating the charging electrode, transfer electrode, separation electrode, etc., resulting in image defects or transfer defects. Furthermore, when the amount of toner scattering increases, backside staining occurs in which the backside of the leading edge of the transfer material is stained with toner.

In addition, fluorine-based resins such as polytetrafluoroethylene and fluoroethylene propylene used as the coating layer of the fixing roll have good electrical insulation properties and are easily negatively charged.
In the technology using positively chargeable inorganic fine particles disclosed in JP-A No. 62-229158, the triboelectricity of the toner particles rises well and image defects due to toner scattering are reduced. Due to the charging property of the toner, electrostatic adhesion to the negatively charged fixing roll increases, resulting in poor offset properties and shortening of the fixing cleaning roll replacement cycle.

On the other hand, as a technique for improving offset properties, there is a technique for containing a low-resistance substance in the heating roll coating layer (Japanese Patent Publication No. 58
-23626), or technology for containing a conductive substance in the primer layer, JP-A-57-150869, JP-A-57-150869, JP-A-57-150869;
No. 83181, No. 59-111177, or a technique for incorporating oxobenzoyl polyether and carbon black into polytetrafluoroethylene used as a heating roll coating layer (Japanese Unexamined Patent Publication No. 100777/1983). There is.

These technologies improve the offset properties and paper wrapping properties around the fixing roll by making the heating roll coating layer conductive. When the resistance of the transfer paper decreases due to moisture absorption, transfer current leaks from the heating roller, resulting in defective transfer and a decrease in transfer efficiency. In addition, if the fixing process is repeated many times, the separating claw or the surface of the heat roller that contacts the temperature sensor may become worn or scratched, resulting in poor mold releasability and the occurrence of image off and set failures. It will be done.

[Purpose of the invention]

Based on the above-mentioned circumstances, the present invention has been developed to provide a toner with good triboelectric charge build-up, stable positive triboelectrification over a long period of time, good transfer performance in a high temperature and high humidity environment, and a fixing roll. It is an object of the present invention to provide an image forming method in which the electrostatic adhesion of toner to the toner is small, the replacement cycle of the fixing cleaning roll is long, and the life of the developer and the maintenance cycle of the fixing device are long.

[Structure of the invention]

The object of the present invention described above is to provide an image forming method in which an electrostatic latent image is formed on a latent image carrier, developed with a developer, and the generated toner image is transferred to a recording material and fixed with a heated roller. The developer contains inorganic fine particles having a pH of 7.0 or more, and a resin coating layer containing dispersed metal coat filler is provided as a surface layer of the roller used for the heat roller fixing, and the core layer is grounded. This is achieved by a characteristic electrophotographic image forming method.

Furthermore, the volume resistivity of the resin coating layer is 10' to 10'' Ωc.
It is preferable that it is m.

Next, the present invention will be explained in detail.

A typical embodiment of the fixing roller according to the present invention is shown in Fig. M1. 3A shows a cross section perpendicular to the axes of the heat roller 1 and the pressure roller 2, and FIG.

The heat roller 1 and the pressure roller 2 are pivotally attached to the copying machine housing so as to be in contact with each other at a predetermined pressure, and generally, a rotation drive mechanism is connected to the heat roller so that the heat roller 1 and the pressure roller 2 rotate freely depending on the pressure roller. provided.

It is preferable to use a conductive material for the bearing used for shaft attachment, and in particular in the present invention, since it is necessary to ground the heat roller l.
It is essential that the bearing 31 is made of conductive material.

The pressure roller 2 has a cylindrical base 2 made of aluminum or the like; and an elastic layer 22 made of an elastic resin material such as silicone rubber.
is provided.

The heat roller l according to the present invention has a cylindrical base 1 made of aluminum or the like.
A release layer 13 is provided on the surface of 1 with a primer layer 2 for adhesion interposed therebetween. Further, a heating heat source, for example, a halogen heater 14, is inserted into the hollow space of the cylindrical base 11. Note that the heat source 14 is not shown in FIG. 1(b).

The surface temperature of the heat roller 1 is detected by a thermistor 4, which is connected to a temperature control means to turn on and off the heat source to maintain the temperature in an appropriate temperature range for fixing without causing offset failure.

The mold release layer 13 is preferably made of a fluorine-based resin with good mold release properties, and in particular, the composition of the resin is polyethylene tetrafluoride-perfluorinated alkyl vinyl ether copolymer (PFA resin), ethylene fluoride-hexafluoride resin, etc. At least one of polypropylene copolymer (FEP resin), polytetrafluoroethylene (PTFE resin)
Preferably, it consists of two.

Furthermore, in the present invention, the volume resistivity of the release layer 13 is adjusted by dispersing and containing a metal coat filler in the resin of the release layer 13. The volume resistivity is 10
A range of ' to 10'' Ω·C11 is preferable.

If the volume resistivity exceeds 101Ω・cam, there is no problem in practicality, but the offset property tends to decrease.
Furthermore, if it is less than 10'Ω·C11, transfer defects may occur in high temperature and high humidity environments.

Furthermore, in the case of the present invention, there are signs that the mold releasability deteriorates due to excessive metal coat filler, and the offset resistance tends to decrease.

At present, the metal coat filler used in the present invention can be divided into three types depending on the shape of the substrate that coats the metal.Firstly, one is a fine ceramic hollow sphere coated with silver, aluminum, copper, zinc, or ferrite. First mentioned is a filler whose surface is coated with a specific gravity of about 0.8, which is lightweight, has a compressive strength of about 3 kg/ma'', and is also excellent in heat resistance. A commercially available product is Metalite A from Toyo Aluminum Co., Ltd.
g, Melatite Au.

Metalite 7 Elite, Ag clad
TV etc. are being shown.

A different type is one in which fine scales or strips of mica, glass, etc. are coated with aluminum, copper, zinc, stainless steel, nickel, etc.
Commercial products based on mica include Toyo Aluminum (
Mica clad Al, Mica clad
Cu, Micr clad Zn, Mica clad
d Stainless steel is an example. There are also those whose base material is glass strips.

A third type is one based on short glass fibers or the like.

FIG. 2 shows the relationship between the vt% of the metal coat filler dispersed in the PFA resin and the volume resistivity Ω·Cl11.

The volume resistivity was measured by vacuum-depositing gold on the surface of a heat roller on which a 20 μm resin film was formed, and then measuring the area lc + m x 1.
am was measured using an electrometer (Kesley 617 programmable electrometer).

As the release resin primer used for the primer layer 12, a commercially available solution type primer mainly composed of fluororesin is used as an adhesive undercoat for the metal material such as iron alloy or aluminum alloy. Specifically, DuPont Tackware (A Primer) 459-882, Mitsui 70 Rochemical 1MP9028N, and the like are used.

The heat roller according to the present invention using the above material is obtained by applying the solution type primer on the aluminum cylindrical base, and then mixing and dispersing powder such as PFA and metal coat filler thereon. Apply the dispersion,
Made by drying and heat treatment if necessary.

The developer according to the present invention is mixed with inorganic fine particles. Examples of such inorganic fine powder include fine silica powder, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, and oxide Examples include chromium, cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride, with silica fine powder being particularly preferred.

The inorganic fine particles used in the present invention are selected from those having a pH of 7.0 or higher.

In addition, p) (measurement was based on the following method.

:Measurement of pH value: Add 100ml of distilled water to 4g of inorganic fine particles and stir vigorously for 5 minutes with a homomixer. Distilled water is boiled to produce CO.

A pH of at least 5.5 is used. Under no circumstances should an alkaline solution be added to increase the pH value.

When measuring, stop stirring and measure the pH value of the solution with a glass electrode pF+ meter. The device is calibrated with a buffer solution before measurements.

Commercially available Nlica fine particles with a pH of 7.0 or higher include [
Aerosil R812j, r Aerosil RX 200J
(manufactured by Nippon Aerosil Co., Ltd.), etc.

Furthermore, it is preferable that these inorganic fine particles be surface-treated with an amine-modified silicone compound to have a pH of 7.0 or more.

The amines include primary, secondary and tertiary amines,
Also included are ammonium salts derived from tertiary amines.

Preferred examples of the amine-modified silicone compound include amino-modified silane coupling agents, amino-modified silicone oils, and polysiloxanes containing ammonium salts (polysiloxane ammonium salts).

A known technique can be used to treat the surface of the inorganic fine particles with the amine-modified silicone compound. Specifically, for example, after dispersing the inorganic fine particles in a solution in which the silicone compound is dissolved in a solvent, , removing the solvent by filtration or spray drying, followed by drying and curing by heating, or using a fluidizing bed device, spraying a solution of the silicone compound dissolved in a solvent to coat the inorganic fine particles; A method may be used in which the solvent is removed by heating and drying to form a film.

The particle size of the inorganic fine particles according to the present invention is such that the average particle size of the primary particles is 3I11μ to 2μm1, particularly 5 to 500L11μm.
It is preferable that it is within the range of . Further, the specific surface area determined by the BET method is preferably 20 to 500 m''/g. If the average particle diameter is too small or the specific surface area is too large, inorganic fine particles may be removed during cleaning using a blade-type cleaning device, for example. It easily slips through, resulting in poor cleaning.

There are cases. On the other hand, when the average particle size is too large or the specific surface area is too small, the fluidity of the developer decreases, making the charging property unstable, and as a result, durability may decrease.

When forming a developer using the above-mentioned inorganic fine particles,
The above-mentioned inorganic fine particles are added to and mixed with the toner particles from the outside, so that they are contained in a state attached to the surface of the toner particles, and a carrier and the like are further mixed therein.

The content ratio of the inorganic fine particles is 0.1 to 5v of the toner.
It is preferably t%, particularly preferably 0.1 to 2wt%. When the content ratio of the inorganic fine particles is too small, the fluidity of the developer may decrease, resulting in poor triboelectric charging properties of the toner, making it difficult to impart an appropriate amount of positive charge to the toner. This may cause fogging.

In addition, when the content ratio is excessive, some of the inorganic fine particles may exist in a free state from the toner particles, and as a result, the free inorganic fine particles may adhere to and transfer to the carrier particles, or the inner wall of the developing device, the developing When the toner adheres and accumulates on the sleeve, regulating blade, etc., and eventually the triboelectricity of the toner becomes poor, making it difficult to apply an appropriate amount of positive charge to the toner, resulting in fogging and a decrease in image density. There is.

Such inorganic fine particles with a pH of 7.0 or higher and whose surfaces are particularly treated with an amine-modified silicone compound become inorganic fine particles with excellent positive chargeability, and are also excellent in moisture resistance and durability, and are not affected by environmental conditions. The result is inorganic fine particles with stable positive triboelectric charging properties.

As the amino-modified silane coupling agent according to the present invention, for example, the following compounds can be preferably used.

HzNCt(zcH2cHzcH2sI (OC1'+
3) s[(,NCH,CH,CH,5i(OC,H,
)3CH3 HJCHzCHzNHCHtCHzCHzSi(0(J
h) zl(,NC0NI(CH2CH□CHtSi(O
CzHs)s82NCFIzCHzNHCH*CH2C
H25t (OCRs) 3H2NCH2CH,NHC
H2CH2N+(CI(2-CH2C1(,5i(OC
H3)3HsC:0COCFIzCH2NHCHzCH
z-Sl(OCHx)iHsC20CO(lJIzcH
2NHCH2CH2NH-CH2CH2C)+2s l
(OCHx) sH, C20COCH2CH2Nl(
CIl, CH2No-CH2CH2NI (CI(2C
H,NHCH,--CH2CHzS1(OCHx)x H3C0COCHI CH2NHCH2CH2NH-C
H, C) 12 CI 2 S i (OCH Yu).

(HsCzO)3SiC)I,CH,CH2H (HsCzO)ssic)12cH2cHzH3CNH
CH,CH,CH,5i(OC2H5)382N(CH
2CH2NH)2C1(2C82CH, -3i(OCH
3) 3H, CN) ICONH.

C3JSt (OCHJs) Examples of commercially available amine-modified silicone oils that can be preferably used include those listed in the table below.

Further, in the above compound, the alkoxy group may be substituted with a chlorine atom. These compounds may be used alone or in combination.

As the amino-modified silicone oil according to the present invention, for example, those represented by the following general formula [1] can be preferably used.

General formula [1] R11 represents an alkylene group, arylene group, aminoalkylene group, etc., R12 and R13 each represent a hydrogen atom, a hydroxyl group, an alkyl group, an aryl group, etc.,
x and y each represent an integer of 1 or more.

The polysiloxane ammonium salt according to the present invention includes:
Dimethylpolysiloxane ammonium salt, which has high positive chargeability and is less likely to cause cleaning defects, is preferred. The dimethylpolysiloxane ammonium salt is generally a dimethylsiloxane containing a structural unit represented by the following formula (A), for example, represented by the structural formula (B).

(A) Formula % Formula % Each group represented by R3 to R includes those having a substituent.

Formula (B) where %R1 is a hydrogen atom, a hydroxy group, an alkyl group,
Aryl group, alkoxy group, or P.

Here, R6 and R7 each represent a hydrogen atom, a hydroxy group, an alkyl group, an aryl group or an alkoxy group,
These groups also include those having substituents. R1~R
X has the same meaning as R l-Rs and X in the formula (A) above. m and n each represent an integer of 1 or more.

Kylene group, arylene group, aralkylene group, -NH-N
Examples include HCO- or a group consisting of any combination of these groups. ), or represents a simple bond, R1, R6
and R6 each represent a hydrogen atom, an alkyl group or an aryl group, and X represents a halogen atom.

Examples include those shown by the structural formula, but these include (CH2)3 CH.

C11゜ IΦ N-CH,・CQ CH.

・ -CzH, -NHz　・CQe CH.

CJ4　NH(CHs)z・CQ CH.

CHI.

-C,H,-N (CHI)3 ・CQCsHs N
HI・CQ CQ \ C, H, OH Polysiloxane ammonium salt is obtained by using an organohalogenated silane having an ammonium salt as a functional group and an organohalogenated silane having no ammonium base in the polymerization step. It can be obtained by a method of introducing it by copolymerization, a method of partially modifying a polysiloxane obtained by polymerization using an organohalogenated silane with an organic group having an ammonium salt as a functional group, and the like. Here, organoalkoxine may be used instead of organohalogenated silane. Moreover, some compounds can also be obtained as commercial products.

The toner for developing electrostatic latent images according to the present invention contains a coloring agent in a binder made of a commonly used toner resin such as a polyester resin, a styrene-acrylic resin, etc. magnetic material in the resin,
It may also contain a property improver.

Examples of the coloring agent include carbon blank, nigrosine dye (C, 1 No. 504158), aniline blue (C, 1, No. 50405), and carfoil blue (C, I).

Noazoic Blue3), Chrome Yellow (C,
], No. 14090), Ultramarine Blue (C,
1, No. 77103), DuPont Oil Red (C
, 1 No. 26105), quinoline yellow (C, 1, N
o47005), methylene blue chloride (C, l
.

No. 52015), phthalocyanine blue (C, 1, N
o74160), malachite green oxalate (C
, I, No. 42000), lamp black (C1,
No. 77266), Rose Bengal (c, 1. No. 4)
5435) and mixtures thereof can be used. The amount of the colorant used is usually 0.1 to 20 parts by weight, particularly preferably 0.5 to IO parts by weight, per 100 parts by weight of the toner.

Examples of the magnetic material include metals or alloys exhibiting ferromagnetism such as ferrite and magnetite, compounds containing these elements, and the like. These magnetic substances are uniformly dispersed in the resin in the form of fine powder with an average particle size of 0.01 to 1 μm, for example, and the content thereof is 20 to 80 parts by weight per 100 parts by weight of toner.

The property improver includes a fixability improver, a charge control agent,
There are others.

As the fixing property improver, for example, polyolefin, fatty acid metal salt, fatty acid ester wax, paraffin wax, polyamide wax, silicone wax, etc. can be used. Especially the softening point (ring and ball method JIS K2
531) is preferably 60-180'C(7) '7').

As the charge control agent, conventionally known ones can be used, and examples thereof include nigrosine dyes, metal-containing dyes, and the like.

To give an example of a preferred method for manufacturing the toner of the present invention, first, a resin material for the binder or a toner component such as a coloring agent added thereto as required is melt-kneaded using, for example, an extruder, and after cooling, a jet A toner having a desired particle size can be obtained by pulverizing the toner using a mill or the like and classifying the powder.

The toner of the present invention is used to develop an electrostatic latent image formed in, for example, an electrophotographic copying machine, and the obtained toner image is electrostatically transferred onto a transfer paper and fixed by an upper heating roller fixing device to be copied. An image is obtained.

In the present invention, the effects of the present invention can be obtained with either a one-component developer consisting only of a non-magnetic toner or a toner containing a magnetic substance, or a two-component developer using a toner and a carrier. can. - Layer In order to maintain excellent charge rise and charge stability and obtain good image quality even after multiple uses, it is preferable to use a two-component developer that uses carrier particles, and furthermore, the carrier particles are toner particles. In order to prevent contamination caused by the like, it is preferable to use a resin-coated carrier coated with a low surface energy resin such as a silicone resin or a fluorine resin, and in particular, it is excellent in the ability to impart positive chargeability to the toner. A carrier coated with a fluorine-based resin is preferred.

The magnetic particles include substances that are strongly magnetized in the direction of a magnetic field, such as metals exhibiting ferromagnetism such as iron, ferrite, and magnetite, nickel, and cobalt, alloys, or compounds containing these elements;
Alloys that do not contain ferromagnetic elements but become ferromagnetic through appropriate heat treatment, such as alloys called Heusler alloys such as manganese-copper-aluminum or manganese-copper-tin, or chromium dioxide. Particles can be used.

〔Example〕

(2) Developer An example of a preferred electrostatic latent image developer of the present invention will be described below.

(Manufacture of binder resin) Dicarboxylic acids and dialcohols shown in Table 1 below were prepared in a four-hole round bottom flask with a capacity of 1Q equipped with a thermometer, a stainless steel stirrer, a glass nitrogen gas introduction tube, and a flowing condenser. Set the flask on a mantle heater, introduce nitrogen gas from the nitrogen gas inlet tube to raise the temperature while keeping the inside of the flask in an inert atmosphere, and then add 0.05 g of dibutyltin oxide. Temperature 200℃
After reacting while keeping at "Viscol 660P" (manufactured by Sanyo Chemical Co., Ltd.)
2 parts by weight of alkylene bis fatty acid amide "Hoechst WaxCJ (manufactured by Hoechst) 2 parts by weight or more of the substances were mixed and melted and kneaded using heated rolls,
After cooling, it is coarsely pulverized, then finely pulverized using a supersonic jet mill, and classified using a wind classifier to obtain an average particle size of 11.0μ.
m toner powder was obtained.

(Manufacture of inorganic fine particles) (1) Inorganic fine particles l (for examples) Put silica fine particles [Aerosil 200J (manufactured by Nippon Aerosil Co., Ltd.) into a mixer, and add the silica fine particles to the silica fine particles.
γ-Aminopropyltriethoxysilane diluted with alcohol so that the amino-modified silane coupling agent was 5 wt % was added and stirred at high speed. The obtained fine powder is 1
After drying at 20°C, the silica is placed in a mixer again and stirred until the viscosity at 25°C is 1.
00cps dimethyl silicone oil is 2wt%
It was sprayed so that The mixture was stirred at high speed for 2 hours at room temperature, further stirred at 160° C. for 15 hours, and then the mixture was further stirred at room temperature for 3 hours at atmospheric pressure to produce inorganic fine particles 1 treated with a nitrogen-containing substance.

These inorganic fine particles l have an average primary particle diameter of 12 mμBE.
The T specific surface area was 130 m''/g.

(2) Inorganic fine particles 2 (for examples) Average particle size is 12+sμ, BET specific surface area is 200m”/
100 parts by weight of silica fine particles "Aerosil 200J (manufactured by Nippon Aerosil Co., Ltd.) of
200cps amino modified silicone oil rs F
8417J (manufactured by Shi Silicone Co., Ltd.) 10 parts by weight and hexamethyldisilazane r S Z 6079J
(manufactured by Toray Silicone) and 100 parts by weight of hexane.
After surface treatment was performed by adding the treatment liquid dissolved in parts by weight dropwise to the high-speed rotating mixer, the contents of the mixer were transferred to a flask and heated at a temperature of 100 to 100°C under an inert gas atmosphere.
By heating at 150° C. for 5 hours while stirring, hexane as a solvent was removed and the reaction was advanced to produce inorganic fine particles 2 treated with a nitrogen-containing substance.

The inorganic fine particles 2 have an average primary particle diameter of 13 mμ, and B
The ET specific surface area was 180 m''/g.

(3) Inorganic Fine Particles 3 (for Examples) Polysiloxane ammonium salt shown below was dissolved in xylene to prepare a treatment liquid.

(X is an integer) Next, silica fine particles "Aerosil 200J (manufactured by Nippon Aerosil Co., Ltd.) are placed in a mixer, and the above-mentioned polysiloxane is sprayed at a ratio of 5 wt% to the silica fine particles. The solvent, xylene, was removed in a flask at a temperature of 200°C for 5 hours with stirring, and the surface was treated with polysiloxane ammonium salt (nitrogen-containing substance) to obtain al-free fine particles. "Fine Particles 3". The inorganic fine particles 3 have an average primary particle diameter of 12 nlZ and a specific surface area of 11 by the BET method.
It's 5m" and 7g.

(4) Inorganic fine particles 4 (for examples) Silica fine particles "Aerosil R812J (manufactured by Nippon Aerosil Co., Ltd.) treated with hexamethyldisilazane are used as inorganic fine particles 4 for examples of the present invention.

The inorganic fine particles 4 have an average primary particle diameter of 7ωμ, BE
The T specific surface area was 200 m2/g.

(5) Inorganic fine particles 5 (for examples) Alumina fine particles "Aerosil RX-Cl (manufactured by Nippon Aerosil Co., Ltd.) treated with hexamethyldisilazane are used as inorganic fine particles 5 for examples of the present invention.

The average particle diameter of the primary particles of the inorganic fine particles 5 is 20+sμ,
The BET specific surface area was 70 m''7g.

(6) Inorganic fine particles (1) (for comparison) Negatively chargeable treated with dimethyldichlorosilane/Rica fine particles r Aerosil R-972JC manufactured by Nippon Aerosil Co., Ltd.)
is referred to as Comparative Example Inorganic Fine Particles (1).

Table 2 lists the pH of each inorganic fine particle.

*■ Value when dispersed at 4% in a 1:1 solution of methanol and water *2 HMPS: Hexamethyldisilazane (manufacturing of carrier) Vinylidene fluoride-ethylene tetrafluoride copolymer rVT-1o
ll (copolymerization molar ratio = 80:20, intrinsic viscosity =
0.95 dQ/g, manufactured by Daikin Industries, Ltd.) and 6 g of methyl methacrylate copolymer [Acrivet MFJ (manufactured by Mitsubishi Rayon Co., Ltd.)] in a mixed solvent of acetone and methyl ethyl ketone (mixed volume ratio = 1: I) 500 m
4 to prepare a coating solution. Using a fluidizing bed device, the coating solution was coated onto I kg of spherical copper-zinc ferrite magnetic particles (manufactured by Nippon Tetsuko Kogyo Co., Ltd.), and then heat treated at 200'C for 5 hours. The aggregate was sieved to produce a carrier having a resin coating layer with a thickness of about 2 μm. The average particle size of this carrier was 82 μm.

(Manufacture of developer) 5 parts by weight of a composite toner obtained by mixing 100 parts by weight of the toner produced by the above method with 0.8 parts by weight of the inorganic fine particles using a Hennel mixer and 100 parts by weight of the carrier were mixed using a V-type mixer. , and mixed to prepare a developer.

(6) Heat Roller Table 3 lists the specifications of the fixing rolls A-H of the present invention and the comparative fixing roll I.

The metal coat filler was added using the method described above.

Copying was evaluated under conditions where the temperature of the heat roller and backup roller was stable.

(2) Evaluation of Offset Properties Table 4 shows the temperatures at which offset occurs when the developer containing each inorganic fine particle produced by the above method is combined with each heat roller.

For evaluation, a modified U-Bix 1550 manufactured by Konica Corporation (linear speed 139 m+a/5ee) was used. In advance, the paper should not be passed sufficiently at 01230°C ◎;240°C
However, the thermal roller of the present invention does not generate offset even when the thermal roller temperature reaches 230° C. in combination with any developer containing inorganic fine particles. Furthermore, when the temperature is 240°C, A and B of the present invention.

Offset may be observed in the G and H heat rollers.

On the other hand, in the heat roller of the comparative example, offset occurs at 210° C. even when the developer containing inorganic fine particles according to the present invention is used in combination, and the roller does not meet the practical level.

Further, in the combination of the heat roller of the comparative example and the developer containing inorganic fine particles of the comparative example, offset may occur at 210'C, and occurrence of offset is definitely observed at 220°C.

■Comprehensive evaluation: Konica (
Co., Ltd. U-Bix1550 modified machine (linear speed 139mm/
Table 5 shows the results of the live-action comprehensive performance evaluation for 5ea).

Note that the fixing temperature was 200°C.

With the combination of the heat roller of the present invention and the developer containing no FI and fine particles of the present invention, (Examples 1 to 8) all had good charging start-up and initial images, and even after 60Kc, the images remained unchanged. It was good.

Among them, the developer containing inorganic fine particles 1 and 2.3 surface-treated with a nitrogen-containing substance according to the present invention had a very stable toner charge amount, so we further evaluated Examples 2 to 5. , the image quality was good up to 100Kc.

On the other hand, in the developer containing inorganic fine particles of the comparative example, stains at the leading edge of the image due to toner scattering occurred by 15KC in any combination with the heat roller.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an a-ra according to the present invention. FIG. 2 is a graph showing the relationship between the metal coat filler dispersed and contained in the PFA resin and the volume resistivity (Ωc+m). 1... Heat roller 2... Pressure roller 11... Cylindrical substrate 12... Primer layer 13... Release layer 14... Heat source 21... Cylindrical substrate 22... Elasticity layer

Claims (1)

[Claims] In an image forming method in which an electrostatic latent image is formed on a latent image carrier, developed with a developer, and the generated toner image is transferred to a recording material and fixed with a heated roller, the developer contains an inorganic material with a pH of 7.0 or more. An electrophotographic image forming method, comprising: providing a resin coating layer containing fine particles and dispersing a metal coat filler as a surface layer of the roller used for the heat roller fixing, and the layer being grounded.