JP2003233221A - Two component developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide two component developer with superior durability even when used in a device with an inorganic photoreceptor. <P>SOLUTION: In the two component developer composed of toner and carrier and used for the device with the inorganic photoreceptor, the carrier is ferrite carrier containing ≤5000 ppm of copper. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-component developer used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method and the like.

[0002]

2. Description of the Related Art Conventionally, the ease of manufacture, the finished state,
From the viewpoint of photoreceptor characteristics and the like, inorganic photoreceptors such as Se and CdS, among others, photoreceptors made of amorphous selenium are widely used. In particular, the advantages of the amorphous selenium photoreceptor are that it has high sensitivity and excellent printing durability, and due to its characteristics, it is desired to be used in high speed machines. However, the background fog is likely to occur even though the charge amount is not reduced.
Therefore, as a solution to such a problem, a color toner containing dark blue has been reported (Japanese Patent Laid-Open No. 2000-1.
No. 47831), there is a limit to the improvement of chromatic color pigments in black toner.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a two-component developer having excellent durability even when used in a device equipped with an inorganic photoconductor.

[0004]

Means for Solving the Problems The present inventors believe that the trace amount of metal impurities in the carrier may contaminate the inorganic photoconductor, and as a result of various investigations, the inclusion of copper contained in the ferrite carrier has been investigated. By adjusting the amount, it was found that the durability of the two-component developer provided with an inorganic photoreceptor is remarkably improved, and the present invention has been completed.

The present invention relates to a two-component developer comprising a toner and a carrier, which is used in an apparatus equipped with an inorganic photoconductor, wherein the carrier is a ferrite carrier having a copper content of 5000 ppm or less. .

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a ferrite carrier having an adjusted copper content is contained in a two-component developer used in a device provided with an inorganic photoconductor, particularly a photoconductor made of amorphous selenium. It is characterized by the fact that The content of copper in the ferrite carrier is 5000 ppm or less, preferably 0.1 to 3000 ppm, more preferably 1 to 1000 ppm, and particularly preferably 10 to 30.
It is 0 ppm.

The main component of the raw material of the ferrite carrier is F
e ₂ O ₃ , with secondary components of MgO, Mn ₃ O ₄ ,
CuO, NiO, ZnO, SrCO ₃ , BaCO ₃ , M
nCO _{3 and the} like are listed, and as additives, A1 ₂ O ₃ ,
SiO ₂ , Bi ₂ O ₃ , CaCO ₃ , V ₂ O ₅ , TiO
₂ , SnO ₂ , PbO and the like can be mentioned, but in the present invention,
From the viewpoint of adjusting magnetic properties and easiness of production, a ferrite carrier containing iron oxide as a main component and containing at least a magnesium compound and / or a manganese compound, and more preferably a manganese compound is preferable. The content of magnesium in the ferrite carrier is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight, and the content of manganese is preferably 0 to 40% by weight, more preferably It is 10 to 35% by weight.

In general, a ferrite carrier is prepared by mixing the above-mentioned raw materials and additives, calcining the mixture at about 1000 ° C., and then immersing the mixture in water and finely pulverizing it with a ball mill to an average particle size of about 1 μm. Polyvinyl alcohol or the like is added as a binder therein, and a defoaming agent, a dispersant or the like is further added to form a slurry. The slurry is granulated with a spray dryer and dried with hot air. Then, after firing at about 1200 ° C. or higher and crushing, a ferrite carrier can be obtained through magnetic selection and classification.
The magnetic characteristics of the ferrite carrier can be adjusted by changing the additive and the amount to be mixed with the raw material mainly containing iron oxide. The content of copper in the ferrite carrier can be adjusted by selecting a raw material such as iron oxide having a smaller content of copper, adjusting the addition amount thereof, and adjusting the content of copper in the firing container.

The surface of the carrier may be further coated with a resin from the viewpoint of charging property, durability and the like. Examples of the coating resin include fluororesin, silicone resin, acrylic resin, styrene-methacrylate resin, styrene-acrylic copolymer resin, polymer resin, polybutadiene resin, and mixed resins thereof.
The resin coating can be performed by dissolving the resin in an organic solvent or the like, applying it to the surface of the carrier by dipping, spraying or the like, and then performing drying or heat curing to form a film.

The two-component developer of the present invention has a saturation magnetization,
From the viewpoint of charging ability, specific gravity, etc., it is not particularly limited as long as it contains the ferrite carrier, and the toner constituting the developer is particularly limited to a normal toner composed of a binder resin, a colorant and the like. Can be used without.

Although the details of the reason why the effect of the present invention is obtained by such a ferrite carrier is not clear, it is presumed as follows. That is, by adjusting the content of copper contained in the ferrite carrier, crystallization on the surface of the inorganic photoconductor, particularly the amorphous selenium photoconductor is suppressed, uniform charging becomes possible, and even the unexposed photoconductor surface portion is obtained. It is not exposed. Therefore, it is considered that the occurrence of background fog can be effectively suppressed in a reversal development type apparatus that irradiates a portion corresponding to a character with light to form a latent image. The chargeability of the developer of the present invention is not particularly limited. However, since the inorganic photoconductor, particularly the amorphous selenium photoconductor is easily positively charged, in the reversal development method using a positively chargeable two-component developer, The effect is particularly remarkable.

Examples of the binder resin include polyester, polyester / styrene-acrylic polymerized resin, mixed resin of polyester and other resin, hybrid resin, styrene-acrylic resin, and the like. Among these, fixing property, durability and From the viewpoint of colorant dispersibility, polyester and hybrid resin are preferable, and polyester is more preferable.

The polyester used in the present invention can be produced, for example, by using the compounds exemplified in JP-A-7-175260 and referring to the method described therein.

As the raw material monomer of the polyester, an alcohol component having a valence of 2 or more and a carboxylic acid component such as a carboxylic acid, a carboxylic acid anhydride or a carboxylic acid ester having a valence of 2 or more are used.

Preferred dihydric alcohol components are alkylene (C2 or C3) oxide adducts of bisphenol A (average addition mole number 1 to 10), ethylene glycol, propylene glycol, 1,6-hexanediol, bisphenol. A, hydrogenated bisphenol A and the like. Preferred trihydric or higher alcohol components are sorbitol, 1,4-sorbitan, pentaerythritol, glycerol, trimethylolpropane and the like.

As the divalent carboxylic acid component, various dicarboxylic acids, succinic acid substituted with an alkyl group or an alkenyl group having 1 to 20 carbon atoms, anhydrides and alkyls of these acids (having 1 to 12 carbon atoms). ) Ester and the like,
Preferred are maleic acid, fumaric acid, terephthalic acid and succinic acid substituted with an alkenyl group having 2 to 20 carbon atoms. Preferred trivalent or higher carboxylic acid components are 1, 2,
Examples thereof include 4-benzenetricarboxylic acid (trimellitic acid), its acid anhydride, and alkyl (C1-12) ester.

When the raw material monomers for the polyester are polymerized, a commonly used esterification catalyst such as dibutyltin oxide may be appropriately used in order to accelerate the reaction.

In the present invention, the hybrid resin is prepared, as described in JP-A-8-171231, from a mixture of two raw material monomers of two polymerization systems each having an independent reaction route, and the two polymerization reactions are carried out. It is obtained by doing.

The above-mentioned two polymerization reactions proceed in independent reaction paths, and it is preferable that the two polymerization reactions are a reaction for producing a polycondensation resin and an addition polymerization resin, respectively. Typical examples of polycondensation resins include polyester and polyester.
Examples thereof include polyamides and polyamides. Typical examples of addition polymerization resins include vinyl polymerization resins obtained by radical polymerization reaction.

Among these, the polyester component can be obtained by using the same divalent or higher alcohol component and carboxylic acid component such as divalent or higher carboxylic acid, carboxylic acid anhydride or carboxylic acid ester as the raw material monomer. .

As the raw material monomer used for forming the polyester / polyamide or the amide component in the polyamide, various known polyamines, aminocarboxylic acids, amino alcohols and the like can be mentioned, preferably hexamethylenediamine and ε-. It is caprolactam.

Raw material monomers used to form the vinyl polymer resin obtained by the addition polymerization reaction include styrene; ethylenically unsaturated monoolefins such as ethylene and propylene: diolefins such as butadiene; ) Ethylenic monocarboxylic acid such as acrylic acid: alkyl of (meth) acrylic acid (having 1 to 18 carbon atoms)
Examples thereof include esters of ethylenic monocarboxylic acids such as esters.

The hybrid resin is prepared by mixing the raw material monomer of the polycondensation resin, the raw material monomer of the addition polymerization resin, a polymerization initiator and the like, and first, at 50 to 180 ° C., a polycondensation reaction is mainly performed by a radical polymerization reaction. A polymer obtained by obtaining an addition polymerization type resin component having a group, then raising the reaction temperature to 190 to 270 ° C., and then forming the polycondensation type resin component mainly by a polycondensation reaction is preferable. By using such a mixture of raw material monomers as a raw material and allowing two independent reactions to proceed, it is possible to efficiently obtain a resin in which the compatibility of two types of resins is improved.

The weight ratio of the polycondensation resin to the addition polymerization resin, that is, the weight ratio of the raw material monomer of the polycondensation resin to the raw material monomer of the addition polymerization resin is usually 50 from the viewpoint of dispersibility of the addition polymerization resin. / 50 to 95/5, preferably 60/40 to 95/5.

Further, the toner used in the present invention includes
Additives such as colorants, mold release agents, charge control agents, conductivity modifiers, extender pigments, reinforcing fillers for fibrous substances, antioxidants, antioxidants, fluidity improvers, cleaning improvers, etc. , May be appropriately contained.

As the colorant, all of the dyes and pigments used as toner colorants can be used. Carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment green B, rhodamine- B base,
Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Disazo Yellow and the like can be used alone or in admixture of two or more, and can be used for black toner, monocolor toner and full color toner Although any of them can be used, black toner is particularly preferable because the effect of the present invention can be more remarkably exhibited. The content of the colorant is the binder resin 1
1 to 10 parts by weight is preferable with respect to 00 parts by weight.

The releasing agent is preferably a low-melting wax having a melting point of 70 to 90 ° C., and examples thereof include ester wax and synthetic wax such as Fischer-Tropsch wax.

Examples of the positively chargeable charge control agent include a nigrosine dye, a triphenylmethane dye containing a tertiary amine as a side chain, a quaternary ammonium salt compound, a polyamine resin, an imidazole derivative, and the like. From the viewpoint of dispersibility and stabilization of the charge amount of the toner, nigrosine dye is preferable. Examples of the negative charge control agent include metal-containing azo dyes, copper phthalocyanine dyes, and metal complexes of alkyl derivatives of salicylic acid. In addition,
Both the positively chargeable charge control agent and the negatively chargeable charge control agent may be contained.

The toner in the present invention may be a toner obtained by any conventionally known method such as a kneading and pulverizing method and an emulsion phase inversion method. From the viewpoint of productivity, the pulverized toner by the kneading and pulverizing method is used. preferable. In the case of pulverized toner by the kneading pulverization method, the binder resin, the colorant, the charge control agent, etc. are uniformly mixed by a mixer such as a Henschel mixer, and then melt-kneaded by a closed kneader or a uniaxial or biaxial extruder. It can be produced by cooling, pulverizing, and classifying.In the emulsion phase inversion method, the binder resin, the colorant, the charge control agent, etc. are dissolved or dispersed in an organic solvent, and then emulsified by adding water, Then, it can be separated and classified to be manufactured. The volume average particle diameter of the toner is preferably 3 to 15 μm. An external additive such as a fluidity improver may be added to the surface of the toner.

In the two-component developer of the present invention obtained by mixing toner and carrier, the weight ratio of toner and carrier (toner / carrier) is 0.5 / 100 to 8/10.
0 is preferable, and 1/100 to 6/100 is more preferable.

The two-component developer of the present invention, preferably the two-component developer which is more positively charged than the chargeability of the selenium photoreceptor, is an electrophotographic apparatus such as a copying machine or a printer, preferably a printer, equipped with an amorphous selenium photoreceptor. Even when used for, since the high-quality image can be obtained without generating the background stain for a long period of time while maintaining the chargeability of the non-exposed portion, it is preferably used in the reversal development type apparatus. Peripheral speed is 3
70 mm / sec or more, further 450-2400 mm
/ Sec sec. The peripheral speed of the photoconductor is the moving speed of the surface of the photoconductor, and when the radius of the photoconductor is γ [mm] and the number of rotations is n [r / sec], 2
It is represented by πγ · n [mm / sec].

[0032]

[Examples] [Copper content in iron oxide and carrier] (1) A sample is prepared by a wet decomposition method shown in the following items. Collect 0.1 g of the sample (iron oxide or carrier) in the decomposition vessel. Using a microwave wet ashing apparatus (A-300 manufactured by PROLABO), 2 ml of sulfuric acid is added and heated to carbonize the sample, and then hydrogen peroxide is gradually added to decompose the sample. Replace the sample in a volumetric flask and add pure water to 50
Increase to ml. (2) Using the ICP emission spectrometer (JY238 manufactured by JobinYbon), elemental analysis of the prepared sample is performed under the following measurement conditions to determine the copper content.

Production Example of Toner Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 48.8 parts by weight (70 mol%), polyoxyethylene (2.2) -2,2-bis ( 4-Hydroxyphenyl) propane 19.5 parts by weight (30 mol%), isododecenyl succinic anhydride 6.1 parts by weight (1
1.5 mol%), 19.5 parts by weight of terephthalic acid (59 mol%), 6.1 parts by weight of trimellitic anhydride (16 mol%), and 0.01 part by weight of dibutyltin oxide as an esterification catalyst. , Nitrogen atmosphere, ASTM D36-86
220 until the softening point measured by
The reaction was carried out at ° C. After the reaction was completed, the mixture was cooled and pulverized to obtain a resin (polyester).

100 parts by weight of the obtained resin, 7 parts by weight of carbon black "Monarch 880" (manufactured by Cabot),
Polypropylene wax "Viscor 660P" (manufactured by Sanyo Kasei Co., Ltd.) 1.5 parts by weight and charge control agent "Bontron"
N-01 "(manufactured by Orient Chemical Industry Co., Ltd., Nigrosine dye) (2.0 parts by weight) is premixed by using a Henschel mixer, melt-kneaded by a twin-screw extruder, cooled, and then subjected to normal pulverization and classification steps. Then, 0.3 part by weight of hydrophobic silica "HVK2150" (manufactured by Clariant Co., Ltd.) was mixed and adhered to the surface of 100 parts by weight of the obtained powder using a Henschel mixer to obtain a toner having a volume average particle size of 10 μm. It was

Carrier Production Example 100 parts by weight of iron oxide (Fe ₂ O ₃ ) shown in Table 1 was added to Table 1
The amount of magnesium oxide (MgO) and / or manganese oxide (Mn ₃ O ₄ ) shown in Table 1 was added, and 100 parts by weight of the resulting mixture was mixed with a binder (polyvinyl alcohol).
1.5 parts by weight and 0.5 parts by weight of the dispersant were added, and water was added so that the slurry concentration became 50% by weight. Wet-pulverize and mix this with an attritor manufactured by Mitsui Mining Co., Ltd. for 1 hour,
A slurry was prepared.

The slurry was granulated and dried with a spray drier, then fired at about 1500 ° C. in a nitrogen atmosphere in an electric furnace and classified with a vibrating sieve to obtain a carrier core material.

Fluorine resin "HYLAR301F" (manufactured by Ausimond) based on 1000 parts by weight of the obtained core material
6 parts by weight, acrylic resin "Dianal BR-80"
Methyl ethyl ketone was added to 4 parts by weight (manufactured by Mitsubishi Rayon Co., Ltd.) to prepare a resin solution for coating the core material. This resin solution was spray-coated on the core material using a fluidized coating device. Then, in the fluidized bed,
Heat treatment at 100 ℃ for 60 minutes, average particle size 110
μm carriers C-1 to C-8 were obtained.

[0038]

[Table 1]

Examples 1 to 6 and Comparative Examples 1 and 2 3 parts by weight of the toner obtained in the above production example and 97 parts by weight of the carrier shown in Table 2 were mixed in a Nauta mixer,
Each developer was obtained.

A reversal development type printer "Infoprint 4000IS" using amorphous selenium as a photoconductor.
l "(manufactured by IBM Japan, Ltd., linear velocity: 106)
6 mm / sec, resolution: 240 dpi, developer magnet roll number: 3), blackening rate 8
% Of the printed pattern was continuously printed on 100,000 sheets using a continuous paper of 11 × 18 inches, and the background fog was evaluated.
The results are shown in Table 2.

[Amount of charge] Measured using a Q / M meter (manufactured by Epping Co.). A specified amount of the developer is put into a cell attached to a Q / M meter, and only the toner is sucked through a sieve (twill weave) having an opening of 32 μm. The voltage change on the carrier that occurs at that time is monitored and 90
The voltage after 2 seconds is converted into the charge amount to obtain the charge amount of the developer.

[Fog] "Model 938 Spectrodensito
meter "(X-Rite, aperture: 20 mm, measurement mode: Yxy, light source: D ₆₅ , viewing angle: 10 degree)
Is used to measure the Y value of the white background portion of the printed paper and the unprinted paper, and the value of the background fog = Y value of the unprinted paper−the white background Y value of the printed paper is obtained.

[0043]

[Table 2]

Example 7 Instead of polyester as a binder resin, Japanese Patent Laid-Open No.
-Developer in the same manner as in Example 1 except that a toner containing 100 parts by weight of a resin (hybrid resin) produced according to the method described in Example 1 of Japanese Patent Publication No. 87839 is used and does not contain polypropylene wax. To prepare. Further, by using this developer and performing continuous printing on 100,000 sheets in the same manner as in Example 1, high quality images without background fog can be continuously obtained as in the case of the developer in Example 1. .

From the above results, it can be seen that the background fog is more likely to occur due to printing durability as the content of copper increases. In particular, Comparative Examples 1 and 2 in which the content of copper exceeds 5000 ppm
Then, the image quality is significantly deteriorated due to the occurrence of background fog.
Since the fluctuations in the charge amount are small in any of the examples and comparative examples, it is understood that the cause of the background fog is not due to the decrease in the charge amount.

[0046]

According to the present invention, there is provided a two-component developer capable of maintaining high image quality for a long time without causing scumming even when used in a device equipped with an inorganic photoconductor, particularly an inorganic photoconductor made of amorphous selenium. can do.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hidenori Tachi             1334 Minato Minato, Wakayama Kao Corporation             Within (72) Inventor Koji Akiyama             1334 Minato Minato, Wakayama Kao Corporation             Within F-term (reference) 2H005 BA02 CB04 DA03 EA10                 2H068 CA11

Claims (5)

[Claims] 1. A device provided with an inorganic photoconductor,
A two-component developer comprising a toner and a carrier, wherein the carrier is a ferrite carrier having a copper content of 5000 ppm or less. 2. The two-component developer according to claim 1, wherein the inorganic photoconductor is a photoconductor made of amorphous selenium. 3. The two-component developer according to claim 1, which is used in a printer in which the peripheral speed of the photoconductor is 370 mm / sec or more. 4. The two-component developer according to claim 1, which is a positively chargeable developer used in a reversal development type apparatus. 5. The two-component developer according to claim 1, wherein the toner is black toner.