JPS59176753A - Developer - Google Patents

Abstract

PURPOSE:To obtain a developer durable and stable against long time uses, and capable of forming a sharp developed image high in resolution by melting fine colloidal particles of a metal oxide and attaching them to the surface of each particle obtained by dispersing a colorant into a binder resin. CONSTITUTION:Fine colloidal particles of metal oxide is melted and attached to the surface of each particle btained by dispersing a colorant into a binder resin. It is desirable that said particles have 5-30mum particle diameter, and 60-200 deg.C softening point. A preferable amt. of said colloidal fine particles to be added to said particles is 1-20wt%, because when <1wt%, various characteristics to be enhanced by attaching the fine particles are made insufficient, and when >20wt%, increase of the effect is not attained and control of the shapes, etc. tend to be made difficult.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developer used for visualizing electrostatic latent images in electrophotography or electrostatic recording.

[Technical background of the invention and its problems]

As an electrophotographic developing method, for example, U.S. Patent No. 2,87
No. 4,063, No. 2,618,552, No. 2,221
, No. 776 and No. 2,902,974, respectively, are known, based on the magnetic brush method, the cascade method, the Nogurada cloud method, the fur brush method, and the like.

Among these methods, the magnetic brush method and the cascade method using a two-component thread developer mainly consisting of toner and carrier are commonly worn. Developing devices using these methods can easily produce images that are relatively stable and of excellent quality.

However, on the other hand, there are drawbacks common to two-component developers as shown below. In other words, ■toner is
Frictional charges are received due to mutual friction between toner and carrier, but in this case, if used for a long time,
The carrier surface becomes contaminated with the toner composition and as a result cannot acquire sufficient charge. (2) The mixture ratio of toner and carrier must be adjusted within a predetermined range; however, if used for a long period of time, the mixture ratio will fluctuate and deviate from the predetermined range. (2) Pig powder or glass beads with oxidized surfaces are generally used as carriers, but in this case, the surface of the photoreceptor is mechanically damaged by these carriers.

For this reason, various developing methods using a one-component developer consisting only of toner have been proposed. And so,
A number of development methods have been proposed that use a developer that is magnetically sensitive and is generally called a magnetic toner. Among these, U.S. Pat.
Products based on No. 1 etc. have been put into practical use. However, these methods also have the following drawbacks. In other words ■
Because magnetic toner with relatively low resistivity is used, it is difficult to electrostatically transfer the developed image on the electrostatic latent image to a supporting member such as plain paper, and in a humid atmosphere. It has disadvantages such as insufficient transfer, and (2) color toner cannot be obtained because the toner contains a large amount of magnetic powder.

However, recently, a developing method using a one-component toner that does not contain magnetic powder and has a high specific resistance has been attracting particular attention.

Such developing methods include, for example, U.S. Pat.
No. 5,847, No. 3.152,012, Special Publication No. 1973
-9475, 45-2877, 54-3624
Examples include methods based on the touchdown method, impression method, and jumping method described in the No. These methods utilize conventional toners used in two-component systems.

However, in this case, various problems associated with the -component system are unavoidable, as described below.

The first problem is the formation of a layer of toner composition on a developer carrier (so-called sleeve) due to long-term use, a so-called filming phenomenon.This phenomenon causes a ghost image to occur. For example, JP-A-55-113071,
In the coating method or charging method for the toner disclosed in Japanese Utility Model Application Publication No. 55-8913, etc., the above-mentioned phenomenon becomes noticeable. In order to solve this problem, a method of adding polytetrafluoroethylene (see Japanese Patent Publication No. 54-654) has been proposed, but this method, like the case of adding water-dispersible silica described later, has been proposed for a long time. Because polytetrafluoroethylene separates from the toner and forms a layer on the developer carrier over a period of use, it is not a perfect solution.

The second problem is fluidity and cohesiveness. That is, in the developing method disclosed in %Kokai No. 52-143831, the toner must be applied extremely thinly and uniformly onto the developer carrier, but in this case, the applied toner has no fluidity. The characteristics of being good and not clumping together are omitted. However, to date, no toner that fully satisfies these properties has been developed.

As a means to improve the fluidity of toner and prevent agglomeration,
The method described in No. 44 and the like has been proposed.

According to these methods, some improvement is possible, but it is still not sufficient, and the following problems may occur.In other words, as described in Japanese Patent Publication No. 54-16219, hydrophobic silica gold is added to the toner. When added externally, with long-term use,
The silica separates from the toner and accumulates on the developer carrier, adversely affecting development. In addition, special public service 54-203
As described in No. 44, in the case where the toner contains hydrophobic silica, in order to obtain the effect, a large amount of hydrophobic silica must be contained, which impairs fixing properties, etc., so this is not a preferable method.

The third problem is the problem of N″ Surobai City 7. That is,
When using the jumping method disclosed in Japanese Patent Application Laid-open No. 55-18657, etc., the donor must be efficiently triboelectrified with the developer carrier, but this is not always possible with conventional toners. do not have. In particular, in color toners, polar Nfl having coloring properties such as dyes are used.
It is not possible to use J-medicine.

Among the above-mentioned developing methods, Japanese Patent Publication No. 41-9475,
45-2877, a non-contact developing method in which an electrostatic image holder and a developer carrier are arranged so that the surface of the electrostatic image holder and the developer layer are not in contact with each other in a developing section was disclosed in Japanese Patent Laid-Open No. 5
Recently, it has been attracting particular attention because it can easily be colored by overlapping development as disclosed in No. 1-77233. In the method described in Japanese Patent Publication No. 4'l-9475, etc., the electrostatic charge on the electrostatic image holding surface causes developer particles to fly due to the electric field formed between the electrostatic image holding surface and the developer carrier. It was designed to visualize electric images.

However, when developing an electrostatic image by the above-mentioned method using a developer commonly used in the past, the developed image obtained has a low resolution and is cut off due to the developer scattering around the image area. This tends to result in poor images. This includes 2
There are two possible major causes. That is, one originates from the distortion of the lines of electric force at the edge of the electrostatic image, and the other originates from the aggregation of developer particles. When the counter electrode is placed with a gap in between the electrostatic image and the area of the electrostatic image holder and the counter electrode is finite, the lines of electric force from the edge of the electrostatic image toward the counter electrode will be distorted. With a light. Figure 1 illustrates such distortion of electric lines of force. ◇The electrostatic image holder 1 is composed of a conductive layer 2 and an electrically shielding layer 3. An electrostatic image is formed on the surface of the dielectric layer 3. is formed. Among the lines of electric force 5 directed from the electrostatic image to the counter electrode 4 arranged parallel to it, those generated from the edge of the electrostatic image draw a curve as shown in the same figure and reach the counter electrode 4. It is incident perpendicularly to this. However, since the electrostatic image is formed by positive charges, the counter electrode 4 and the conductive layer 2 are grounded. FIG. 2 shows an example in which the electrostatic image holder 1 and the counter electrode 4 have a curved surface. become noticeable. Figure 3 shows the force that acts on a charged particle with a negative charge when placed in such an electric field, and the locus of motion when the charged particle flies under the action of this force. . An upward electrostatic force F1 perpendicular to the counter electrode 4 acts on the charged particles 30 placed near the counter electrode 4, and the charged particles 30 start flying upward. Inertial force F2 and electrostatic force F1' act on the flying charged particles 31, and the charged particles 3 receive a force in the direction of the resultant force F3 of these forces. Since the direction of F is different from the direction of the electrostatic force FI', the trajectory 32 of the flight of the charged particles 31 deviates from the lines of electric force, and the charged particles 3 reach an area where no electrostatic image exists. Toner scattering around the image area occurs through this mechanism. As the mass of the charged particles, ie, the toner, increases, the inertial force F increases, so that the toner's arrival point is further away from the area where the electrostatic image exists, and toner scattering becomes more pronounced. Furthermore, when the developer particles aggregate, the mass of the toner increases, the inertial force F increases, and the point where the toner reaches is far away from the area where the electrostatic image exists. Furthermore, due to the impact upon arrival, the agglomerated state is broken and the phenomenon of toner scattering becomes more noticeable as shown in FIG. As described above, in the developing method described in Japanese Patent Publication No. 41-9475, etc., toner scattering around the image area is an unavoidable problem when conventional developers are used.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and it can be used for a long time without causing filming on developer carriers and photoreceptors, is stable, has excellent fluidity and agglomeration resistance, and is efficient. The purpose of the present invention is to provide a small amount of developer which can be easily rubbed, has little toner scattering around the image area, and can form a sharp developed image with high resolution.

[Summary of the invention]

The gist of the present invention is to obtain a developer having the various effects described above by fusing colloidal fine particles of gold FA oxide onto the surface of particles made by dispersing a coloring agent in a binder resin. do.

Thermoplastic resins are used as the binder resin, such as various styrene resins, various acrylic resins, polyethylene, polypropylene, polyamide resins, polyesters, maleic acid resins, coumarone resins, polyurethane resins, and polyvinyl chloride. , I-vinyl acetate, I-vinyl butyral, polyvinylidene chloride, phenolic resins, polyethers, or copolymers thereof or cellulose resins, asphalt, dammar, and even thermosetting resins such as epoxy before adding a curing agent. Examples include resin oligomers and the like.

The coloring agent generally includes dyes, pigments, carbon black, etc., and in some cases, mixtures thereof or magnetic powder may also be used. Such coloring agents include, for example, dyes such as nigrosine dyes, carmine dyes, various basic dyes, acid dyes, oil dyes, and anthraquinone dyes; benzidine-based yellow organic pigments, quinanthrine-based organic pigments, and rhodamine-based organic pigments. Pigments such as inorganic pigments such as , phthalocyanine organic pigments, zinc oxide, titanium oxide, and red iron oxide; Caden black such as furnace black, acetylene black, and thermal black; Magnetic powders such as γ-Fe3O4, N1, Fe, and Co. be able to.

The particles preferably have a particle size in the range of 5 to 30 μm. It is desirable that the softening point of such particles be in the range of 60 to 200° C. for reasons described later. In addition, the softening point here means the value measured by the Linde and Gaull method specified in JISK-2531.

As the colloidal fine particles of the metal oxide, Irrsμ
Chemical formula 5in2°Ti with primary particle size of ~0.1μ
O2a At205, ZnO, Fe2O3, Ni2
O3# or At203 and 5102. TlO2 and At20
3. A mixed oxide of TiO2 and 5i02 can be mentioned. Among these colloidal fine particles, silicon dioxide (S102) is particularly useful because it has relatively high resistance and excellent charging properties. Further, the amount of colloidal fine particles attached to the particles (colored particles) is preferably in the range of 1 to 20% by weight. The reason for this is that when the amount of colloidal fine particles attached is less than 1% by weight, the improvement in maneuverability due to the attachment of the fine particles cannot be sufficiently achieved;
Is it foolish that the effect of the adhesion does not change even if the amount is exceeded?
This can easily become an obstacle when adjusting the shape, etc.

In addition, if necessary, the relative humidity of the developer may be 40% or more.
Hydrophobized colloidal fine particles may be used in order to withstand even under the i environment.

Further, in order to obtain a developer having positive polarity and stable chargeability, colloidal fine particles may be treated with a silane coupling agent having an amine group.

Such coupling agents include, for example, the product name KBM-
602, KBM-603 (both manufactured by Shin-Etsu Silicon)
, 5f (6020 (manufactured by Toshi Silicone Co., Ltd.), A-11
00, A-1120 (both manufactured by Nippon Unicar Co., Ltd.), and the like. When colloidal fine particles are treated with such a silane coupling agent, their hygroscopicity slightly increases, so it is desirable to use hydrophobized colloidal fine particles.

Next, a manufacturing method for obtaining the developer of the present invention will be explained below by showing an example.

First, binder resin and colorant are mixed in a gall mill, ■ type mixer,
After mixing using a Sm mixer, Kooning blender, etc., the resulting mixture is kneaded using a double-arm knee 2-1 three roll, co-kneader, pressure kneader 1, etc. The powder is pulverized using a pulverizer such as a ball mill, and the resulting powder is further classified using a sieve, an air classifier, etc. to produce particles (colored particles) of a predetermined particle size. When manufacturing such colored particles, the binder resin used must be adjusted to suit the softening point of the colorant to be dispersed. The one with the dot is selected.

For example, when a large amount of carbon black, which has a large surface area and a large oil absorption capacity, is added as a coloring agent, the softening point of the binder resin used may be as low as 200°C; When adding a small amount of coloring agent that dissolves in the binder resin, the softening point of the binder resin used should be 20
It may be a value close to 0°C. For this reason, among the binder resins mentioned above, it is difficult to use low molecular weight polyethylene, polypropylene, or polyamide resins with softening points in the range of 60 to 180°C, and the use of such resins improves pressure sensitivity. This makes it possible to obtain a developer having high pressure fixing properties.

Next, the colored particles and the colloidal fine particles of the metal oxide are mixed for a predetermined time using a mixer such as a sol mill, a type mixing rod, a Henschel mixer, or a Kooning blender, so that the colloidal fine particles are attached to the surface of the colored particles.

Next, the colloidal fine particles adhering to the surface of the colored particles are fused to the surface to firmly bind them together, and a developer having a generally spherical overall shape is produced. This step is performed using a thermal granulation device. As this device, for example, the
The apparatus for spheronizing thermoplastic particles disclosed in No. 2165 and the like is applied.

In other words, this device has a hot air temperature of 200°C from the heat exchanger.
~600℃, hot air flow rate 0.1-5 rr//min, particle dispersion air flow rate 0.1-2 rr//min, particle concentration 7-10
014/i and a pressure of 0.01 to 2 kg/lrI, the colored particles melt and firmly fuse the lubricant fine powder attached to the surface to themselves. be able to.

In the above-mentioned fusing step, the softening point of the colored particles becomes a problem. That is, when the softening point of colored particles exceeds 200°C, it is necessary to raise the hot air temperature to 600°C or higher in order to melt the colored particles using the above device, but this is difficult to operate the device. At the same time, there is a risk that the binder resin will be thermally decomposed and its initial properties will deteriorate.

In addition, the lower limit of the softening point of the colored particles is set at 60°C because if the temperature near the recovery section of the device exceeds 60°C, the developer obtained will be deformed and agglomeration will easily occur. [Effects of the Invention] According to the developer of the present invention, the following glaze effects can be achieved.

(1) A stable developer that can withstand long-term use without causing filming on developer carriers, photoreceptors, etc. can be obtained.

((1) A developer with good fluidity and agglomeration resistance can be obtained.

(li(l) A developer capable of efficient triboelectrification is obtained.

A developer compatible with a 4ψ-component non-contact development method can be obtained.

In the M-component non-contact development method, a sharp image with high resolution can be obtained without any toner scattering around the image area.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to Examples.

Example 1 92 negative parts of styrene-n-butyl methacrylate copolymer (Hima SBM-73F, manufactured by Sanyo Kasei@) and 8 liter parts of carbon black (MA-8; Mitsubishi Kasei M) were mixed in a sol mill for about 2 hours. After that, the mixture was kneaded for about 2 hours using a double-arm kneader.

After cooling the kneaded material, it was roughly pulverized with a hammer mill, and further classified using a jet mill to obtain colored particles having a particle size of 5 to 10 μm. These colored particles had sufficient performance for heat fixing in conventional two-component developers, and their softening point was 118°C.

Next, 100 parts by weight of the colored particles and 1ON base of colloidal fine particles (Aerosil 300, 1 manufactured by Nippon Aerosil Co., Ltd.) were mixed in a ball mill to adhere the colloidal fine particles to the surface of the colored particles. Next, this was put into a thermal granulation device disclosed in Japanese Patent Publication No. 55-2165.
Hot air temperature 400℃, hot air volume 1-7 minutes, particle dispersion air flow rate 0
．． IJ 1 minute, particle law 10! -/lt? Under the conditions of
The treatment was performed at a pressure of approximately 0.1 kycd. The colloidal fine particles were fused to the colored particles, and at the same time, a developer having a spherical shape as a whole was obtained.

Therefore, the charging properties, fluidity, cohesiveness, foot shield properties, and stability of the developer of Example 1 and the developer made of the colored particles (Comparative Example 1) were comparatively measured. .

(1) Charging characteristics A two-component developer was prepared from each developer using a carrier (TEF V2O0/300゜Japan Iron Powder ■jB), and a plow-off charge amount measuring device (Electrophotography, 16, (1977
) 52; Journal of the Society of Electrostatics, 4° (1980) 1.34
), the charging characteristics were measured.

As a result, the charging characteristics of the developer of Example 1 were 1938
At μC/9-, the start-up was quick, and the stirring time remained almost constant even when the stirring time was changed, indicating stability.

On the other hand, Comparative Example 1 had a C) of 27 .mu.C/f-, and as the stirring time increased, the charge amount decreased to 0.21 .mu.C/7 at a stirring time of 48 hours, which lacked stability.

(2) Fluidity The fluidity was investigated by measuring the angle of repose. The devices are A, B, and D.
A powder property measuring device (manufactured by Tsutsui Rikagaku Kikai ■) was used.

As a result, the angle of repose of the developer of Example 1 was 34°.

That of the developer of Comparative Example 1 was 61°, and the fluidity was significantly improved.

(3) Cohesiveness After putting the sample into a 1 oomt wide-mouth bottle and tapping it several dozen times, it was left in a 60° C. constant temperature bath for 24 hours. At that time, the state of aggregation of each developer was observed with the naked eye.

Although no aggregation phenomenon was observed in the developer of Example 1,
The developer of Comparative Example 1 aggregated into blocks.

(4) Fixability A fixing test was conducted in an oven fixing device at 180°C. The developers of Example 1 and Comparative Example 1 both exhibited good fixing properties.

(5) Stability The one-component non-magnetic developing device shown in FIG. 5 was attached to the developing section of a PPC electronic copying machine (ReoDry BD716) next summer, and repeated development tests were conducted.

In addition, 51 in the figure is a developer carrying member that supports the developer and supplies it to the latent image surface, 52 is a stirring blade that stirs the developer, and 5
3 is a hot spring 4 N for storing developer; 54 is a developing bias; 55 is an elastic blade for thinly and uniformly depositing the developer on the developer carrier 1; 56 is a developer;
A selenium photoreceptor 57 is an electrostatic image carrier, and a latent image 58 having an electrostatic charge is formed on the surface of the selenium photoreceptor.

The developing conditions are: developing bias 54: 200 VN peripheral speed of Igushihokirou latent image holding member 57: 80 mm/sec, developer carrier 5;
The gap between the latent image holding member 1 and the latent image holding member 57 was 200 μm.

In the case of Example 1, an extremely uniform thin layer of developer 56 is obtained, and the elastic blade 55 and developer carrier 5
The surface potential of the thin layer of developer 56 due to friction with
It was confirmed that the battery was charged uniformly at ±5V.

Even after repeating the developing operation about 100,000 times, no filming occurred on the developer carrier 5 and the latent image holder 52, and they were extremely stable.

On the other hand, in the case of Comparative Example 1, a uniform layer of the developer 56 was not obtained, the layer thickness was thick, and the charging was e50±12.
There was a wide variation in V. The image is Kavli,
It is a low quality product with a lot of uneven density, and it is about 10,000 yen.
Filming occurred after 0 iterations.

(6) Humidity Dependency The above copying machine was set in a test room where the relative humidity could be controlled within the range of 20% to 90%, and a development test was conducted. Example 1
In an environment where the relative humidity exceeded 40%, poor development and transfer occurred, and a sufficient image could not be obtained.

This is due to the hygroscopicity of the colloidal fine particles used in the examples.

Therefore, a similar trial was made using hydrophobicized colloidal fine particles CR976 (manufactured by Nippon Aeronol Co., Ltd.) instead of the above-mentioned Aerosil 300 (manufactured by Nippon Aerotsuru Co., Ltd.).

As a result, charging characteristics e41μC/n・r, angle of repose 33°
In addition, a clear image with no development defects or transfer defects was obtained even in an environment with a relative humidity of 80%.

Polystyrene (D-125, manufactured by Esso Petrochemical) 60
Parts by weight, styrene-butadiene copolymer (2007J,
B) 20 parts by weight of low molecular weight polyethylene (manufactured by Zeon ■), low molecular weight polyethylene (
Sunwax 151-P, manufactured by Sanyo Chemical ■) 10 stacked parts,
After mixing 10 parts by weight of Carbon Brass (Raben 40, manufactured by Columbian, USA) in a Henschel mixer for about 10 minutes, the mixture was kneaded 3 to 5 times with a triple roll.

After cooling, the mixture was coarsely pulverized with a hammer mill and classified using an emitter to obtain colored particles of 5 to 10 μm.

100 parts by weight of these colored particles and hydrophobic silica (R972,
(manufactured by Nippon Aerosil ■) using a Kooning blender to adhere hydrophobic silica to the surface of the colored particles. The softening point of this particle was 175°C. The colored particles have sufficient performance as a conventional two-component developer for heat rolls.

Next, the colored particles 100 to which the hydrophobic silica was attached
Parts by weight and 10 parts by weight of hydrophobic colloidal fine particles R974 (manufactured by Nippon Aerosil Co., Ltd.) were mixed in a Lumil, and the colloidal fine particles were adhered to the surface of the colored particles.

Subsequently, this was subjected to a fusion treatment using the thermal granulation apparatus of Example 1 under the same conditions except that the hot air temperature was 600° C. to obtain a developer.

The developer of Example 2 and the developer made of colored particles to which hydrophobic silica was attached (Comparative Example 2) were tested in the same manner as in Example 1 to determine charging characteristics, fluidity, cohesiveness, fixing properties, and the like. Stability was measured. The results are summarized in Table 1.

Example 3 Colloidal fine particles used in Example 1 (Aerosil 300
), the surface of colloidal silicon dioxide was treated with a silane coupling agent and a hydrophobizing agent having an amine group.
A developer was produced in the same manner as in Example 1 using H200 (manufactured by Nippon Aerosil Co., Ltd.).

The developer obtained is Teiden lid ■20μq? When developed using this, no capri was observed in the image. In this case, a zinc oxide photoreceptor was used instead of a selenium photoreceptor. Further, when a test was conducted using colloidal silicon dioxide in which the amount of the silane coupling agent added was varied, the effect appeared when the amount added was 1% by weight, and the effect became saturated when the amount exceeded 10M.

Furthermore, similar effects can be obtained by using silane coupling agents such as 5H6020 (manufactured by Toshi Silicone), A-1100, A-1120 (all manufactured by Nippon Unicar), and KBM602 (manufactured by Shin-Etsu Silicone). Ta.

Example 4 92 parts by weight of low molecular weight polypropylene (Viscol 550-p, manufactured by Sanyo Kasei ■) and 7 talocyanine blue organic pigment CI 74260 (Fast Dan Blue 5007)
, manufactured by Dainippon Ink ■) for about 5 minutes in a Henschel mixer, and then kneaded in a pressurized second machine. The softening point of the mixer was 156°C. After cooling it, crush it,
Colored particles with a particle size of 5 to 10 μm were prepared by classification.

Next, 100 parts by weight of the colored particles and 10 parts by weight of colloidal fine particles R972 (manufactured by Nippon Aerosil Co., Ltd.) were added. - A developer was prepared in the same manner as in Example 1 after mixing for 10 hours in "Lumil". about,
The respective characteristics were measured in the same manner as in Example 1. The results are summarized in Table 2.

Example 5 In place of the low molecular weight polypropylene of Example 4, a low molecular weight polyamide (Persamide 940; manufactured by Daiichi General@) was used.
A developer was produced in the same manner as in Example 4 except that . This developer exhibited good properties similar to those of Example 4.

Examples 6 to 12 Styrene-acrylic resin (JR-1000; manufactured by Sanyo Kasei Co., Ltd.) was used instead of polystyrene in Example 2, and partially crosslinked styrene-acrylic resin (S- 115; manufactured by Nippon Zeon Co., Ltd.), multi-colored particles were prepared in the same manner as in Example 2, and colloidal fine particles R976 were added to 100 parts by weight of the colored particles.
(manufactured by Nippon Aerosil Co., Ltd.) in the amounts shown in Table 3 to produce seven types of developers in the same manner as in Example 2.

Therefore, the various percent properties of the developers of Examples 6 to 12 were examined in the same manner as in Example 1.

The results are also listed in Table 3.

Example 13 With the composition of Example 2, the particle size is 2 to 5 μm and 14 to 7 μm.
15~10μrn, 6~12μm, 10~20μm
Five types of colored particles were treated in the same manner as in Example 2 to produce a developer. These five types of developers were placed in the developing device shown in FIG. 5, and development was carried out under the same conditions as in Example 1'' to examine the resolution of each developer. As a result, the characteristic diagram shown in Figure 6 was obtained. As is clear from FIG. 6, when a developer with a particle size of 10 μm or less is used,
A good developed image with a resolution of 6 ip/1 m or more was obtained. 3 tp when using a developer with a particle size of 11 μm or more
/Im or less, toner scattering around the image area was noticeable. The particle diameter was measured using a Coulter Counter (manufactured by Nikkaki Co., Ltd.).

Example 14 Colored particles 10 with a particle size of 5 to 10 μm used in Example 13
0 parts by weight, 10 parts by weight of colloidal fine particles (R974; manufactured by Nippon Aerosil Co., Ltd.) were put into a sol mill and processed, and then the hot air temperature of the thermal granulation device was set to 350°C and 600°C to obtain 2 parts with different shapes. A seed developer was produced. The developer processed at 350°C had a slightly rounded amorphous shape, and the developer processed at 600°C had a spherical shape.

As a result of applying a developer to the above two glazes in the developing device shown in FIG. 5 and developing them under the same conditions as in Example 1, 3
The amorphous developer processed at 50°C showed some toner scattering around the image area, whereas the spherical developer processed at 600°C showed no toner scattering around the image area.

Example 15 Colored particles 10 with a particle size of 5 to 10 μm used in Example 13
10 parts by weight of the former and 0.1 to 10 parts by weight of the latter were added to 0 parts by weight of colloidal fine particles of R974 (manufactured by Nippon Aerosil Co., Ltd.) and aluminum oxide C (manufactured by Nippon Aerosil Co., Ltd.) to change the specific resistance by 10 to 10 Ωcrn. A developer was produced.

Note that the manufacturing method is exactly the same as in Example 6.

Each of the obtained developers was developed under the same conditions as in Example 1, and the copy density with respect to the specific resistance of the developer was investigated, and the characteristic diagram shown in FIG. 7 was obtained. As is clear from FIG. 7, the developed image is clear when using a developer having a resistance of 10@9 Ωm or less, but the transfer is poor and the image density is low. Therefore, it is desirable that the specific resistance of the developer is 100 m or more.

Example 16 When the developers of Examples 6 to 12 were placed in the developing device shown in FIG. 5 and developed, toner scattering was observed around the image area with the developers of Examples 6 and 7. On the other hand, Example 8
It is not observed at all in the developer Nos. 1 to 12, and therefore, it is desirable that the angle of repose of the developer is 35° or less.・Example 17 0.1 to 10 parts by weight of a polarity control agent such as a metal-containing azo dye or nigrosine dye was added to the colored particles of Example 1, and the developer carrier was then processed in the same manner as in Example 1. The amount of triboelectric charge with is 0.1 to 10μC/? A developer was produced.

When each developer was placed in the developing device shown in FIG. 5 and developed in the same manner as in Example 1, the copy quality against the amount of triboelectric charge of the developer was investigated, and the characteristics shown in FIG. 8 were obtained. I got the diagram. As is clear from Fig. 8, <, 0.1 to 1μ
C/P friction f'4 JI4. ? Since it was difficult for the developer to adhere to the carrier 5, uneven development was often observed.

On the other hand, in the case of a developer of 2 μC/fl- or more, the developer adhered uniformly onto the carrier 51, and a cylindrical image with uniform density was obtained.

Example 18 10 to 150 parts by weight of magnetic powder (BL-100* manufactured by Titanium Kogyo Co., Ltd.) was added to the composition of Example 1 to prepare developers having different specific gravities.

When each developer was placed in the developing device shown in FIG. 5 and developed in the same manner as in Example 1, the resolution with respect to the specific gravity of the developer was investigated, and the characteristic diagram shown in FIG. 9 was obtained. .

As is clear from FIG. 9, when a developer with a specific gravity of 1.5 or more is used, there is no toner scattering around the image and the resolution is 6.
It was possible to obtain images that were sharper than LpAm.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of electric lines of force generated from an electrostatic image, and Figures 3 and 4 are illustrations of the force acting on charged particles in the electric field formed by the electrostatic image, and the forces acting on charged particles, respectively. Fig. 5 is a cross-sectional view of a bag portion showing one form of the developing device used in the present invention, and Fig. 6 shows the particle diameter of the developer and the resolution of the obtained copy image. Figure 7 is a characteristic diagram showing the relationship between the resistivity of the developer and the density of the copy image obtained. Figure 8 is the amount of frictional charge between the developer and the developer holder and the copy image. Characteristic diagram showing the relationship with the concentration of
The figure is a characteristic diagram showing the relationship between the specific gravity of developer particles and the resolution of a copy image obtained. DESCRIPTION OF SYMBOLS 1... Electrostatic image holder, 2... Conductive layer, 3... Dielectric layer, 4... Counter electrode, 5... Lines of electric force, 30.3
DESCRIPTION OF SYMBOLS 1... Charged particle, 32... Trajectory, 5... Developer carrier, 52... Stirring blade, 53... Hopper, 5
4... Bias, 55... Elastic blade, 56...
- Developer, 57... Electrostatic image holder, 58... Latent material. Applicant's representative Patent attorney Takehiko Suzue Figure 2 Figure 3 Figure 4 Figure 5 Figure 5 61 611 4m) Figure 7 1101---L---3---Ya 3 20 22

Claims (9)

[Claims] (1) A developer characterized in that colloidal fine particles of a metal oxide are fused to the surface of particles made by dispersing a coloring agent in a solidifying resin. (2) The developer according to claim 1, wherein the particles have a softening point in a temperature range of 60 to 200°C.・ (3) The developer according to claim 1 or claim 2, characterized in that the colloidal fine particles are fused to the particles in a weight ratio of 1 to 20% by weight. (4) The developer according to claim 3, wherein the colloidal fine particles are hydrophobized. (5) Developer 0 according to claim 3, wherein the colloidal fine particles are treated with a silane coupling agent having an amine group. (6) The developer according to claim 5, wherein the colloidal fine particles are made hydrophobic after being treated with a silane coupling agent having an amine group. (7) The developer according to claim 1, characterized in that colloidal fine particles of metal oxide are fused to the surfaces of the particles to make them spherical. (8) The developer according to claim 1, characterized in that colloidal fine particles of a metal oxide are fused to the surface of the particles to have a specific resistance of 10,100 or more. (9) The developer according to claim 1, characterized in that colloidal fine particles of a metal oxide are fused to the surface of the particles so that the angle of repose is 35° or less.