JPH0954455A - Developing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a stable image even when the environment changes by using such a toner that contains color particles containing a binder resin and a coloring agent and specified composite fine particles. SOLUTION: In this developing method, an image is developed by using a two-component developer comprising a toner and a carrier at the nearest position between a latent image holding body and a developer holding body. The toner consists of color particles containing a binder resin and a coloring agent and composite fine particles. The composite fine particles are obtd. by treating the surface of inorg. fine particles with a resin essentially comprising a resin obtd. by addition condensation polymn. or condensation polymn. The resin is preferably a polyester resin or melamine resin. Or, the toner is preferably produced by depositing or embedding the composite fine particles on the surface of the color particles. Since these fine particles are not simple particles but have a structure containing hard inorg. fine particles, the toner hardly deforms even when development is repeatedly performed for lots of times. Moreover, since the toner has the resin on its surface, the charge amt. does not decrease even when the toner is stirred in a high temp. and high humidity environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method using an electrostatic charge image developing toner such as electrophotography, electrostatic recording and electrostatic photography.

[0002]

2. Description of the Related Art In recent years, with the progress of electrophotographic technology, electrophotographic technology has been widely used not only as a copying machine but also as an output terminal for printers, fax machines and the like. In particular, since the electrophotographic technique utilizes triboelectrification properties, it is required to exhibit stable triboelectrification properties under any environment and even when used many times.

As a developing method, there are used a developing method using one component of toner alone and a developing method using two components of a mixture of toner and carrier at the position closest to the latent image carrier and the developer carrier. 2 from the viewpoint of stabilizing the charging property
A developing method using a component developer is excellent.

However, in a system in which only inorganic fine particles are externally added to the toner as a fluidizing agent, the charge amount decreases depending on the number of times of development in a high temperature and high humidity environment, especially when developing a large number of sheets with a small printing area. Can be seen, fog,
There was a problem such as toner scattering.

For improving the characteristics in a high temperature and high humidity environment, a technique has been proposed in which fine particles composed of only a specific resin are added, as disclosed in JP-A-64-49052. However, in the case of fine particles composed only of resin, the fine particles are deformed by the mixing stress in the developing machine. The deformed particles hinder the triboelectric charging between the toner carriers,
This was a cause of toner scattering and fogging.

Particles containing fine inorganic particles in resin fine particles are disclosed in Japanese Patent Application Laid-Open No. 4-39669, etc., but the resins listed here have a particularly large printing area under high temperature and high humidity. No effect has been found on the environmental stabilization of the charging characteristics when developing a small number of sheets.

For this reason, at present, no developer has been completed which can stabilize the charging characteristics under high temperature and high humidity, especially when developing a large number of sheets with a small printing area.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing method capable of forming a stable image even when the environment changes. In particular, it is an object of the present invention to provide a developing method capable of imparting a stable charging property even when developing a large number of sheets with a small printing area under a high temperature and high humidity environment and capable of forming a stable image.

[0009]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies and, as a result, have found that two components composed of a toner and a carrier are located at the closest position between the latent image carrier and the developer carrier. In the developing method of developing with a developer,
A toner containing colored particles containing a binder resin and a colorant, and composite fine particles whose surface is treated with an addition condensation polymerization reaction system or a resin containing a condensation polymerization reaction system resin as a main component. It was achieved by a development method characterized by:

It is more preferable that the resin is a polyester resin or a melamine resin. It is also a preferred embodiment that the toner is a toner in which the composite fine particles are embedded in the surface of the colored particles or on the surface.

In the present invention, not only resin fine particles but
Since it is a structure containing hard inorganic fine particles, it does not deform even during a large number of developments, and since it has the resin shown in the present invention on its surface, the charge amount is high even under stirring in a high temperature and high humidity environment. It never drops. Even if the environment changes, it is possible to maintain stable chargeability.

The structure of the present invention will be specifically described below.
The composite fine particles constituting the toner of the present invention are obtained by subjecting the surface of the inorganic fine particles to a surface treatment with a resin. As the resin component, a conventionally known resin can be used. The reaction type resin has a remarkable effect of preventing the decrease in the charge amount due to the mixing in a high temperature and high humidity environment as compared with other resins such as addition polymerization resins. Above all, the effect of the polyester resin, the urethane-modified polyester resin, and the melamine resin is particularly remarkable, and the dispersibility in the toner is also good.

The polyester resin used in the present invention is obtained by condensation polymerization of a carboxylic acid having a valence of 2 or more and an alcohol component having a valence of 2 or more.

As the divalent carboxylic acid, maleic acid,
Fumaric acid, citraconic acid, itaconic acid, glutacoic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecylsuccinic acid, n-dodecenylsuccinic acid, isododecylsuccinic acid Acid, isododecenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, etc. are mentioned, and these acid anhydrides can also be used.

As the dihydric alcohol component, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxypropylene (3.
3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4
-Hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2
-Etherified bisphenols such as bis (4-hydroxyphenyl) propane, polyoxypropylene (6.6) -2,2-bis (4-hydroxyphenyl) propane,
Ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,
3-propylene glycol, 1,4-butanediol,
1,4, butenediol, neopentyl glycol,
1,5-pentane glycol, 1,6-hexane glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, bisphenol Z, hydrogenated bisphenol A and the like can be mentioned. Further, a cross-linking resin having a three-dimensional network structure is preferable from the viewpoint of the deformation resistance of the fine particles. For that purpose, it is preferable to add a trivalent acid and an alcohol as shown below.

As the trivalent carboxylic acid, 1,2,4-
Benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid,
1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-
Examples thereof include cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empol trimer acid. These acid anhydrides can also be used.

As the trihydric alcohol component, sorbitol, 1,2,3,6-hexanetetrol, 1,4-
Sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-
Examples thereof include 1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

As the polyester resin, a urethane-modified polyester resin formed by reacting an isocyanate compound with residual hydroxyl groups of a normal polyester resin is also preferably used in the present invention.

Examples of the isocyanate compound include hexamethylene diisocyanate, isophorone diisocyanate, toluylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, triphenylmethane triisocyanate, an adduct of trimethylolpropane and toluylene diisocyanate, and the above isocyanate compound. Oligomers of can also be used.

The melamine resin according to the present invention can be prepared by subjecting a derivative of melamine and formaldehyde to an addition polymerization reaction. For example, as a derivative from melamine, melamine, methylolmelamine, methylated melamine, methylated methylolmelamine, butylated melamine,
Examples include butylated methylol melamine and hexamethylol melamine.

The inorganic fine particles contained in the composite fine particles include silica, alumina, titania, barium titanate, aluminum titanate, magnesium titanate,
Calcium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, antimony trioxide, zirconium oxide, tungsten oxide, copper oxide, tin oxide,
Inorganic compounds such as tellurium oxide, manganese oxide, boron oxide, silicon carbide, titanium carbide, boron carbide, silicon nitride, titanium nitride, and boron nitride, and metals such as copper, aluminum, and zinc can be used.

The volume average particle size of the composite fine particles is 5 nm to 30.
It is 0 nm, more preferably 10 nm to 200 nm.

The particle size ratio of the composite fine particles to the toner is preferably 1/300 to 1/3 of the number average particle size of the toner. If the particle size ratio is 1/300 or less, it becomes difficult to obtain the effect of improving the characteristics at high temperature and high humidity, and if it is 1/3 or more, the dispersibility in the toner is deteriorated.

The ratio of the resin added to the inorganic fine particles is
0.005 wt% / 99.995 wt% -60 wt% /
40 wt% is preferable. If the resin component is 0.005 wt% or less, the effect of improving the characteristics at high temperature and high humidity does not appear, and 80w
If it is t% or more, it is likely to be deformed due to the mixing stress, which causes a charge inhibition.

<Production Method of Composite Fine Particles> Method of Polymerizing Resin Monomers of Resin Fine Particles in the Presence of Inorganic Fine Particles This method is a method of encapsulating an inorganic fine powder with a resin forming fine particles. It is important to increase the affinity of the inorganic fine particles, and the following methods can be applied.

A) The surface of the inorganic fine particles is preliminarily subjected to adsorption treatment or reaction treatment with an organic polymer, a surfactant or the like to form a surface having an affinity for the resin monomer constituting the fine particles, and the inorganic fine particles are formed. A method of polymerizing a monomer of a resin with a core as a core to encapsulate inorganic fine particles.

B) In the presence of the inorganic fine particles, the monomer of the resin constituting the fine particles is polymerized to form a resin having an ionic group terminal having a polarity opposite to that of the surface charge of the inorganic fine powder, and electrostatic charges of both charges are formed. A method of encapsulating inorganic fine powder with resin by attractive force.

Method of producing composite fine particles after pretreatment of inorganic fine particles by kneading with resin Specifically, resin powder and inorganic fine particles are mixed and kneaded to produce a powder, and the powder is dissolved in a solvent. After that, there is a method of mixing this with a poor solvent for the resin to produce the composite fine particles, or a method of dissolving and then cooling to produce the composite fine particles.

Method Using Emulsion Polymerization Inorganic fine particles are mixed with a resin monomer constituting the fine particles to prepare a dispersion liquid. Then, the dispersion liquid is emulsified in a solution containing a surfactant and emulsion-polymerized to obtain fine particles containing inorganic fine particles.

<Other Toner Additives> In the present invention, in addition to the composite fine particles of the present invention, known inorganic fine particles used as a general fluidizing agent may be added.

In particular, the number average primary particle diameter of these known inorganic fine particles is smaller than the number average primary particle diameter of the composite fine particles of the present invention, and the addition amount is preferably not more than the addition amount of the composite fine particles of the present invention. .

If the average particle size is larger than that of the composite fine particles of the present invention or if the addition amount is large, the effect of the present invention can be obtained because the charges generated by the charging of the toner and the carrier leak under high temperature and high humidity. Hateful.

As the toner base of the present invention, conventionally known toner can be used. The number average particle size of the toner is 3 to
15 μm is preferred.

<Dispersing Means of Composite Fine Particles in Toner> Conventionally known dispersing means for external addition treatment can be used. In addition, the effect of the present invention is more remarkable when the fixing treatment is performed on the toner surface by thermal or mechanical energy during dispersion, which is particularly preferable.

In order to carry out such a toner treatment, it is preferable to carry out the dispersion within the range of the glass transition point (Tg) ± 20 ° C. of the toner as a dispersion condition.

After carrying out such fixing treatment, the composite fine particles of the present invention and the inorganic fine particles generally used as a fluidizing agent may be further added externally.

<Amount Added to Toner> The total amount of the composite fine particles of the present invention added to the toner is preferably 0.5 to 20 wt%. If it is 0.5 wt% or less, the effect of the present invention is difficult to obtain, and if it is 20 wt% or more, the charging between the toner and the carrier is hindered.

When the toner of the present invention is used as a constituent of a two-component developer, a conventionally known carrier can be used. The volume average particle size of the carrier is 10 to
150 μm is preferred.

[0039]

【Example】

1. Preparation of composite fine particles 1-A. Preparation of fine particles (inorganic fine particles treated with polyester resin) 0.755 g of terephthalic acid, 0.697 g of 1,4-butanediol and butyl were added to a three-necked flask equipped with a high-speed stirrer, a reflux condenser and a carbon monoxide introducing tube. Add 3 mg of hydroxytin oxide and keep at 250 ° C. until the reaction is complete. After cooling, the contents are dissolved in THF, SiO ₂ (particle size 10 nm) is added as inorganic fine particles, and the mixture is stirred in a water bath for 7 days.
Heat to 0 ° C. After that, the contents are vacuum-dried and fine particles A are added.
I got

1-B. Preparation of fine particles (inorganic fine particles treated with polyester resin) As the resin raw material of 1-A, bisphenol A propylene oxide 0.05 mol, terephthalic acid 0.02
mol, trimellitic acid 0.02 mol, butylhydroxytin oxide 3 mg, and Al as inorganic fine particles
Fine particles B were obtained in the same manner except that ₂ O ₃ (particle size 150 nm) was used.

1-C. Preparation of Fine Particles (Inorganic Fine Particles Treated with Crosslinking Polyester) As the resin raw material for 1-B, bisphenol A propylene oxide 0.05 mol, terephthalic acid 0.02
mol, trimellitic acid 0.02 mol, butylhydroxytin oxide 3 mg, and Ti as inorganic fine particles
Fine particles C were obtained in the same manner except that O ₂ (particle size 100 nm) was used.

1-D. Preparation of Fine Particles (Inorganic Fine Particles Treated with Urethane Modified Polyester Resin) As the inorganic fine particles of 1-B, MgO (particle diameter 50 nm)
After preparing a resin using the above, fine particles D were obtained by modifying with 0.02 mol of hexamethylene diisocyanate.

1-E. Preparation of fine particles (inorganic fine particles treated with melamine resin) ZnO (particle size 180 nm) as inorganic fine particles in a reaction vessel
10 g, 0.378 g of melamine, and 200 g of a 0.37% formaldehyde aqueous solution adjusted to pH 7.5 with a 10% sodium hydroxide aqueous solution are charged, and the mixture is stirred and heated to 70 ° C. in a water bath until the mixture is completely dissolved. 1 more
After heating for 0 minutes, the reaction is stopped and cooled. Then, the contents were vacuum dried to obtain fine particles E.

1-F. Comparative particles (inorganic particles treated with addition polymerization resin) SiO ₂ (particle size 10 nm) as inorganic particles in the reaction vessel
10 g of styrene, 50 g of styrene, 1 g of azobisisobutyronitrile and 0.5 g of sodium salt of di-2-ethylhexyl sulfosuccinate were reacted in ethanol under a nitrogen stream at 70 ° C. for about 2 hours, and then vacuum dried. Comparative particles F were obtained.

1-G. Comparative Particles (Polyester Particles Without Inorganic Fine Particles) Comparative particles G were obtained in the same manner except that the inorganic fine particles in Example 1-B were not added.

1-H. Comparative particles (inorganic fine particles without resin treatment) Inorganic fine particles TiO ₂ (particle size 100 nm) were prepared.

2. Preparation of colored particles Polyester resin (100 parts), carbon black (5
Part), low molecular weight polypropylene (3 parts) are mixed and kneaded,
The particles were pulverized and classified to obtain colored particles having an average particle size of 11 μm.
The Tg of the colored particles was 55 ° C.

3. Dispersion treatment on colored particles 3-1. External Addition Treatment The colored particles were mixed with 0.5 wt% of fine particles (1-AE) and 0.5 wt% of hydrophobic silica having a number average particle diameter of 10 nm using a Henschel mixer to obtain a toner.

3-2. Fixing treatment 0.5 wt% of colored particles and fine particles (1-AE) are mixed using a Henschel mixer with a temperature control function so that the product temperature is 70 ° C, and then cooled to 20 ° C. 0.5 wt% of hydrophobic silica having an average particle diameter of 10 nm was added and further mixed to obtain a toner.

4. Preparation of carrier St-MM is formed on the surface of ferrite core material with an average particle size of 80 μm.
A copolymer resin (St / MMA = 4/6) was coated to obtain a coated carrier.

5. Preparation of Developer Using the above toner and carrier, 15 g of toner and 285 g of carrier were prepared using a V-type mixer.

<Measurement method> Composite fine particles and inorganic fine particles Number average particle diameter: Transmission electron microscope JEM-2000FX
Image analysis device SPICA after observation with JEOL Ltd.
The number average particle size was determined by (manufactured by Nippon Avionics Co., Ltd.).

Toner number average particle size: measured by Coulter counter Tg: measured by DSC20 manufactured by Seiko Instruments Inc.

The glass transition point is a value measured by DSC, and the intersection of the baseline and the slope of the endothermic peak is taken as the glass transition point. Specifically, using a differential scanning calorimeter, 1
The temperature is raised to 00 ° C., left at that temperature for 3 minutes, and then cooled to room temperature at a falling temperature of 10 ° C./min. Then,
When this sample was measured at a temperature rising rate of 10 ° C./min, the intersection point between the extension line of the baseline below the glass transition point and the tangent line showing the maximum slope from the rising portion of the peak to the peak apex was determined. It is shown as a glass transition point.

<Evaluation> In the evaluation as an example, running was performed while continuously changing the environment and the printing rate.

Low temperature and low humidity (10 ° C, 20% RH) (L
L) prints an A4 original with a print rate of 10% 10,000 times. Print rate 1 at high temperature and high humidity (35 ° C, 80% RH) (HH).
Printing 0% A4 originals 10,000 times The running was performed by changing the A4 originals with a printing rate of 1% to 10,000 times printing at high temperature and high humidity (HH).

The print ratio refers to the area ratio of the print portion of an A4 original.

The image forming apparatus is U-made by Konica Corporation.
It was carried out using a BIX1112 machine.

The evaluation of the image density was carried out by measuring the solid black portion of the copied image with an RD918 type densitometer manufactured by Macbeth.

For evaluation of fog, the relative density of the white background portion of the copied image was measured by the above-mentioned density measuring device.

To evaluate the toner scattering, the scattering was visually confirmed and classified into the following four ranks.

A: No scattering was observed B: Occurrence was observed on the upper lid near the sleeve of the developing machine C: Occurrence was seen on the entire upper lid of the developing machine D: Scattering was observed on almost all inside the machine.

[0063]

[Table 1]

It can be seen from Table 1 that the developing method of the present invention can impart a stable charging property under a high temperature and high humidity environment, especially when developing a large number of sheets having a small printing area, and can form a stable image. I understand.

[0065]

According to the present invention, it is possible to obtain a developing method capable of forming a stable image even when the environment is changed, and particularly, it is stable even when developing a large number of sheets under a high temperature and high humidity environment with a particularly small printing area. Thus, a developing method capable of imparting the charged property and forming a stable image was obtained.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03G 15/08 507 G03G 9/08 372 384

Claims (4)

[Claims] 1. A development method of developing using a two-component developer comprising a toner and a carrier at the position closest to the latent image carrier and the developer carrier, wherein the toner contains a binder resin and a colorant. And a composite fine particle whose surface is treated with a resin containing an addition condensation polymerization reaction system resin or a condensation polymerization reaction system resin as a main component. 2. The developing method according to claim 1, wherein the resin is a polyester resin. 3. The developing method according to claim 1, wherein the resin is a melamine resin. 4. The developing method according to claim 1, wherein the toner is a toner in which the composite fine particles are embedded in or on the surface of the colored particles.