JPH06130733A - Method of magnetism-agitation- area development - Google Patents

Abstract

PURPOSE: To provide a magnetic agitating area development method which improves the flow characteristics of a developer by passing this developer through the nonmagnetic region of a developer housing. CONSTITUTION: This magnetic agitating area development method includes the provision of the developing area existing between a transporting member having a rotary magnet 5 for transporting developer particles 8 which contain toners contg. resins, pigments, charge additive particles and surface additive particles and carriers contg. cores of soft ferrite or sponge iron, etc., subjected or not subjected to coating or subjected to partial coating and an image forming member 1. In this magnetic agitating area development method, the carriers have magnetic field magnetization of about <10emu/g and the developer 8 is transported to a photoconductive image forming member 1 by the transporting device. The toners adheres to the image on the image forming member 1, thereby giving rise to development.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to developing methods and, more particularly, the invention relates to an improved magnetic stir zone developing method that provides excellent developer flow, especially through the non-magnetic regions of the developer housing. Regarding In one embodiment, the present invention relates to a magnetic stir zone development method of the type described in US Pat. No. 4,565,765. The disclosure of this U.S. Pat. No. 4,565,765 is incorporated herein by reference, in which a soft ferrite carrier is selected as the developer. The carrier is usually coated with a polymer or mixture of polymers. As a reference, for example, US Pat. No. 4,937,
166 and 4,935,326, the disclosures of which are incorporated herein by reference. The advantages associated with the method of the present invention include the ability to use conventional manufacturing techniques and coating methods to form soft ferrite carrier particles with optimal charging characteristics and easy transfer of developer through the developer housing. It includes what you can do. These advantages have been achieved in the examples by using magnetic stir zone development methods and compositions that use soft ferrite or iron carriers, where the carriers have improved flow properties.

[0002]

2. Description of the Related Art In the patentability search report, the following US patents are cited. First, US Pat. No. 4,764,445 discloses electrophotographic hard ferrite magnetic carrier particles for use in two-component developers, in which the ferrite has a maximum retention of at least 300 Oersted when magnetically saturated. It may have a hexagonal crystal structure with magnetic force (see columns 2 to 5). Next 4,73
No. 2,835 discloses a carrier containing spherical magnetic particle material used in electrophotographic developers. At first glance, the shape and composition of the ferrite particles give the toner good fluidity (see, for example, columns 3 and 4). Also, the fourth, 640,
No. 880 discloses a magnetic brush development method using a semiconductive carrier. This carrier can crush the toner agglomerates by mechanical force to increase the fluidity of the toner (see columns 3, 4). No. 4,277,552 discloses a magnetic developing method using a magnetic powder having a high coercive force, a magnetic toner containing toner particles, and a magnetic roll (see columns 3 and 4). No. 4,623,603 discloses a spherical magnetic zincate type hexagonal ferrite carrier powder (see columns 2 and 3). U.S. Pat. No. 4,546,060 also discloses, for example, a development system in which a synthetic carrier type material can be selected that includes a resin and a hard ferrite having a maximum coercive force of at least 300 Gauss. .

[0003]

It is a feature of the present invention to provide a magnetic stir zone developing method which uses carrier core particles or fine particles of soft ferrite or sponge iron to improve its flow characteristics. These and other features of the present invention have been achieved in the Examples by providing a magnetic stir zone development method in which soft ferrite or sponge iron carrier core particles or particulates are selected. More particularly, the present invention relates to a magnetic stir zone development method using a developer composition comprising a toner and a carrier of soft ferrite or sponge iron, such as copper zinc ferrite available from Steward Chemical, in which case The carrier can be coated with a polymer or a mixture of polymers.

In an embodiment, the present invention is directed to a magnetic stir zone development method that includes providing a development zone between an imaging member and a transport member. The transport member includes roll means such as a rotating shell containing a rotating magnet for transporting developer particles. Further, the developer particles include a toner containing a resin, a pigment, charge additive particles, and surface additive particles,
A carrier comprising a coated or uncoated or partially coated core. In this case, the carrier has a zero field magnetization in the range of 0 to 9 below about 10 emu / g, the developer is transported by the transport member to the photoconductive imaging member, and the toner is deposited on the imaging member. Development occurs by adhering to an image.

[0005]

SUMMARY OF THE INVENTION A magnetic stir zone developing method according to the present invention comprises a toner containing a resin, a pigment, charge additive particles and surface additive particles, coated or uncoated or partially coated. A magnetic stir zone development method comprising providing a development zone between a carrier member comprising a rotating magnet for conveying developer particles including a carrier including a core being coated and an imaging member. Wherein the carrier has a zero field magnetization of less than about 10 emu / g, and the developer is transported by the transport member to the photoconductive imaging member and the toner adheres to the image on the imaging member. It is characterized in that development occurs.

The magnetic stir zone development method is illustrated in FIG. 1 and in FIGS. 1-3 of US Pat. No. 4,565,765. FIG. 1 corresponds to FIG. 1 of US Pat. No. 4,565,765, where US Pat.
Image forming member 1 and transport and development roll means as described in No. 90 are shown. US Patent 4,265,
The disclosure of No. 990 is incorporated herein by reference. The transport developing roll means is a shell 3 which is stationary or is rotating in a direction opposite to the rotating direction of the rotating magnet 5 therein, developer particles 8, and a developing container 9.
And pickoff baffle 11 and mixed paddle wheel 1
3, developer container means 15 (not shown), toner or a mixture of toner and carrier replenishing and distributing means 16,
Trim bar or measuring slit 17 and intermediate transfer roll 1
9 and a fixed magnet 21. The relative directions of movement of the members are indicated by arrows. Generally, during operation, the image forming member 1 moves in the direction opposite to the movement of the magnet 5. By this movement, the developer particles are conveyed to the developing area between the image forming member 1 and the shell 3, and the toner particles contained in this developing area are agitated. When the image forming member 1 is moving in the same direction as the movement of the magnet 5, a higher background is generally generated, which is not preferable.
However, stirring of the developer by the rotating magnet 5 can be achieved without depending on the direction of movement of the image forming member 1. A more detailed description of this method is given in US Pat. No. 4,565,765.

Examples of suitable toner resins selected in the process of the present invention and present in the toner in various effective amounts, such as from about 70% to about 95% by weight, include polyesters.
Includes ester polymerization products of styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-butadiene copolymer, polyamide, epoxy resin, polyurethane, polyolefin, vinyl resin and dicarboxylic acid, and diol containing diphenol. Be done.

A number of suitable known pigments can be selected as the colorant for the toner particles, such as Cabot Corporation.
n) available from Regal 330 (registered trademark) and Columbian Chemicals (Columbia).
Raven available from n Chemicals (RA
VEN) 5250®, carbon black, nigrosine dyes, aniline blue, phthalocyanine derivatives, magnetite and mixtures thereof.

As the pigment or colorant, magenta, cyan,
Color toner compositions containing and / or yellow particles and mixtures thereof are also included in the scope of the present invention. Examples of optional charge enhancing additives that are present in various effective amounts, such as from about 0.1 to about 20% by weight include US Pat. No. 4,298,
Alkylpyridinium halides such as cetylpyridinium chloride of 672, U.S. Pat. No. 4,338,
No. 390, cetylpyridinium tetrafluoroborate, quaternary ammonium sulfate, sulfonate charge control agents, stearylphenethyldimethylammonium tosylate, and distearyldimethylammonium such as US Pat. No. 4,560,635. Included are methyl sulfate, stearyl dimethyl hydrogen ammonium tosylate, and other known similar charge enhancing additives. Negative charge enhancing additives that may be used include aluminum salicylate and potassium tetraphenylborate. For the toner, silica such as Aerosil R972 (registered trademark) as a surface additive, metal oxide such as tin oxide, titanium oxide and aluminum oxide, metal salt of fatty acid such as zinc stearate, Silicas treated with charge additives and Petrolite Corp.
available from Unilation
N) (registered trademark), US Pat. No. 5,102,7
Reference can be made to No. 55 polymeric hydroxy compound. These additives, which may be present as a mixture, are added in effective amounts, the amount being, for example, about 0.1.
To about 5% by weight, with about 0.1 to about 1% by weight being preferred.

The linear polymer uniline has a fully saturated hydrocarbon backbone with at least 80% polymer chains terminated at one end by a hydroxyl group. This alcohol has the general formula C
It is represented by H ₃ (CH ₂ ) _n CH ₂ OH. Where n is about 3
A number from 0 to about 300, from about 30 to about 100
Is preferred. These alcohols are available from Petrolite Corporation.

Carrier particles that can be selected for mixing with the toner compositions of the present invention include carrier particles that can triboelectrically obtain a charge of a polarity opposite to that of the toner particles. More specifically, as the carrier particles of the present invention, it is possible to select negative carrier particles to which positively charged toner particles can be attached. Alternatively, the carrier particles having a positive polarity can be selected so that the toner composition having a negative polarity can be used. The selected carrier particles are considered to be magnetically weak, their remanence is less than 10 emu / g, for example it is zero magnetic field.
The field is about 0 to about 9 emu / g, which is, for example, zero magnetic field (zero applied magne).
It corresponds to the magnetic intensity in tic field). Examples of suitable carrier particles include particles with a particle size of 50 and 65 μm.
emu / g nickel zinc ferrite, particle size diameter 65 and 90 μm, 50 emu / g copper zinc ferrite, 65 μm
Zinc ferrite called Stabilized Magnetite, available from Powdertech Corporation at 72 emu / g at m, 62 emu / g at 50 μm, 68 em at 60 μm.
Copper Zinc Ferrite available from Steward Chemical at u / g, Hoeganoes Corporation at 50 and 60 μm
Includes ferrites such as sponge iron available from. The magnetization of the sponge iron core is not considered to be saturated in the magnetic field normally used in xerography (about 800 Gauss), so a more appropriate value is the intensity at 800 Gauss, which is about 85 emu / g. Is.

The polymer carrier coating comprises a vinyl chloride-chlorotrifluoroethylene copolymer which may include conductive particles such as carbon black therein and US Pat. Nos. 3,467,634 and 3,3. 52
A polyvinylidene fluoride resin as in 6,533,
Fluorinated polymers such as poly (chlorotrifluoroethylene), fluorinated ethylene-propylene copolymers, and US Pat. Nos. 3,467,634 and 3,526,533.
Of styrene, methyl methacrylate and silane such as triethoxysilane, polytetrafluoroethylene, polyacrylic acid containing fluorine, polymethacrylic acid and vinyl chloride. A polymer,
Many known coatings are included, such as trichlorofluoroethylene and other known coatings. A soft ferrite core, which is a copper-zinc ferrite core with a dual polymer coating on the core, is preferably selected as the carrier component and is described in US Pat. No. 4,937,166.
And No. 4,935,326, the disclosures of which are incorporated herein by reference.

Examples of special carrier cores are nickel-zinc ferrites with a d × M product of less than 4000, copper-zinc ferrites with a d × M product of less than 4000, and a d × M product of 50.
A soft ferrite selected from the group consisting of zinc ferrites less than 00, the developer being at least 4
Adjusted to a concentration of wt%. Here, d is the diameter (μm) of the core particle, and M is the saturation magnetization (emu /
g).

The invention and advantages described herein are preferably obtained by preparing a toner composition by the method of providing wax or uniline as an external component, preferably in an amount of about 0.05 to about 5% by weight. . further,
The resulting toner particles, including wax, generally have an average diameter of about 1 to about 50 μm.

[0015]

EXAMPLES Table 1 shows the performance of many different core materials evaluated on a manually operated roll machine including the magnet construction of FIG. 10 g of carrier, core, pile of developer to be analyzed are placed on the roll and the roll is rotated at about 20 cm per second. Note down the behavior of the material and after repeating the test of manually forming a pile on the roll. The poorly moving material barely spreads from the initial ridges or retains its original shape when manually re-peaked. Materials with poor movement are classified or evaluated in Table 1 with a minus sign (-). Materials that behave well spread quickly around the roll and are clearly agitated by the rotation of the roll. Materials that perform well are classified or rated in Table 1 with a plus sign (+). The material in between takes a considerable amount of time to spread after being collected. This intermediate material is classified in Table 1 by the open circle symbol (o).
It has been found that the consistent and smooth operation of the toner and developer of the present invention where the carrier is, for example, soft ferrite, in the above equipment corresponds to excellent flowability and excellent agitation in a xerographic machine. .

Virtually all ferrite, iron and steel cores behave poorly in this device without the use of toner. In particular, in Table 1, CuZn PT1 and NiZ
Only n PT1 behaves relatively well in the evaluation without coating. These are materials that have the best combination of small grain size and low saturation magnetization, and the properties of small grain size and low saturation magnetization generally result in good performance on rolls. All other cores recorded show poor behavior when evaluated without toner.

It is a feature of the invention that all of the evaluated cores have excellent on-roll properties when adjusted to a sufficiently high toner concentration with the appropriate toner. Therefore, for example, when toner 2 was used to adjust the toner concentration to 7% by weight, all the cores had excellent characteristics. In Toner 1, all but one of the six cores at 7 wt% with somewhat inferior properties have a particle size of 90 μm or greater. Good performance is generally found in those with smaller core particle size and lower saturation magnetization. Therefore, the ferrite having a product of the diameter and the saturation magnetization (d × M) of less than 4000 μm-emu / g has excellent properties as described above except for one, and has the same properties as the St1 of CuZn and the toner 1. With one exception, all toners and 4% by weight have excellent flowability. CuZn St1 was also coated with various polymers and demonstrated good performance as shown in Table 1 when used in a fully functional developer housing as described herein.

Although sponge iron cores may require high toner concentrations to obtain adequate flowability, none of the sponge iron cores tested (denoted as Fe) were tested with all toners and 7 wt. Good performance is shown at a toner concentration of%. The magnetization of sponge iron core is more than that of ferrite.
Its functional limits may differ from ferrite in some instances, as it changes with changes in the magnetic field.

The exact toner concentration required for good flow characteristics will vary with the design of the magnet in the developer housing, toner component, carrier component, etc. Smaller carriers appear to be suitable for higher toner concentrations. Carrier charge generation is related to surface area per mass, which is inversely proportional to diameter. Therefore, a small carrier can sufficiently charge a large amount of toner, and is more suitable for achieving a high toner concentration. Particle size is 65 μm
The following carriers are preferred for embodiments of the present invention.

The product of the diameter and the saturation magnetization (d × M) is useful for classifying carriers, but it is not possible to clearly distinguish between good and bad behavior. In particular, Zn PT
1 or stabilized magnetite behaves better than this expected standard, probably because the material has a relatively low density of about 2.20, resulting in low magnetic strength per unit volume. is there. Therefore, the magnetic field at the carrier bead is lower.

However, the behavior on the roll cannot be completely predicted only by the characteristics of the carrier core. This is because the results for Toner 1 are often worse than the results for Toner 2 and Toner 3. Although small particle size and low magnetic strength are the norm, performance with individual toners is often empirical. The compositions of the various toners evaluated are set forth in Note C for Table 1.

Further, the carrier obtained from the core of the present invention is a highly functional magnetic stirring zone enhancer (MAZE = Magnet).
ically aggregated zone enha
It has been shown that it can be used to obtain an nced) developer. In particular, St1 of CuZn is the quinal (KYN) described in US Pat. Nos. 5,015,550, 4,937,166 and 4,935,326.
AR (R) and PMMA mixtures have been coated in various proportions and coating weights and then mixed with different toners to make a developer. Examples of such developers are summarized in Table 2. Mean value of charge ratio (Q / M or friction) to mass by conventional blowoff friction measurement and charge by diameter (Q / D) by charge spectrograph described in US Pat. No. 4,375,673. The values (average and width) are also listed in Table 2. The various toner compositions evaluated are shown at the end of Table 2. All carriers in Table 2 are based on the CuZn St1 core in Table 1.

The marking machine used to produce xerographic copies from these MAZE developers has an operating speed of 6.8 inches per second (40 cpm).
Variable speed electric circuit board operated by
Xerox Corporation converted into a speed breadboard
Tion) 1075 machine MAZ developer housing. An overview of the MAZE developer housing is shown in Figure 1 above. The 27 mm diameter developer roll 3 includes a harmonic magnet 5 consisting of eight electrodes that rotate in the operating direction and rotate in the opposite direction. The magnetic intensity of the peak is about 500 gauss on the roll surface. The transport roll 19 pulls up the developer from the paddle wheel 13 and carries the developer on one surface to the measuring slit 17. The developer material is pulled up through the slit and circulates through the (wrapped) development zone. The developer is removed from the roll 3 by an iron scraping blade 11 which is maintained on the surface of the roll 3 by a magnetic force and which is vertically positioned.

As shown in Table 2, the Q / M average value and
The Q / D average value and the width of the Q / D distribution change considerably. Excellent carrier bead movement and agitation was observed around developer roll 3 for all developers. Therefore,
The flowability of the developer is independent of the individual charging level when the toner concentration exceeds 4% by weight. Developer operation (r
un) 7, 9 and 12 only have suitable charge levels and charge distributions for proper development without high background.

[0025]

[Table 1]

Notes on Table 1 a = toner flow rate:-= poor flowability on roll, forming persistent peaks + = good flowability and agitation even after manual peaking Having: o = intermediate flowability, peaks disappear slowly Carrier: CuZn = copper zinc ferrite NiZn = nickel zinc ferrite Zn = zinc ferrite Fe = sponge iron b = manufacturer: PT = powder tech, St = steward, Ho = Heuga Knows c = Toner Concentration (wt%) and Toner Composition Toner 1: 0.7% Aerosil R972 on surface
And 10% of Raven 5250 ™ carbon black from Colombian Chemicals in a styrene-n-butylmethacrylate copolymer with 0.7% zinc stearate Toner 2: PLIOTONE. ) (Registered trademark) styrene-butadiene copolymer with 5% HOSTAPERM PINK (trademark),
Includes 1% dimethyl distearyl ammonium methyl sulphate (DDAMS) Toner 3: Toner 2 with 20% DDAMS surface treated Aerosil R812® 0.4% d = According to manufacturer's specifications Diameter of a given carrier core (μm), saturation magnetization and density e = magnetization measured at 800 Gauss instead of saturation magnetization

[0027]

[Table 2]

Toners used in Table 2 Toner 4: 92% styrene-n-butylmethacrylate copolymer mixed with 6% Regal 330 and 2% cetylpyridinium chloride Toner 5: 80% Pliotone styrene-butadiene co-polymer. Polymer, 16% magnetite, 3% legal 33
Mixture of 0, 1% dimethyl distearyl ammonium methyl sulphate (DDAMS) Toner 6: 92.5% styrene-n-butyl methacrylate copolymer, 6% Legal 330, 1.5% DDA
Mixture of MS and 0.5% Aerosil R972 Toner 7: 63.38% styrene-butadiene copolymer, 21.12% crosslinked (divinylbenzene) styrene-
n-Butyl Methacrylate Copolymer, 10% Legal 3
30, 5% 660P ™ wax, 0.5% DDA
MS, 0.3% aminosilane treated Aerosil R9
Toner 8: 75% pliotone styrene-butadiene copolymer, 6.72% styrene-n-butylmethacrylate copolymer, 5.72% legal 330, 1.0%
DDAMS, 1.0% Litol Scarlet (LITH
OL SCARLET ™, a 50:50 mixture of 0.56% Hostaperm Pink and styrene-n-butyl methacrylate copolymer and 0.3% Aerosil R9.
Toner 9: 85% Priotone Styrene-Butadiene Copolymer, 4% MAPICO BL
ACK) (registered trademark), 10% legal 330, 1.0
% DDAMS, 0.15% aminosilane treated Aerosil R972, 0.25% Unilin wax blend Aerosil R972 and Unilin are present on the toner surface.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a magnetic stirring zone developing method according to the present invention.

[Explanation of reference numerals] 1 image forming member 3 shell 5 rotating magnet 8 developer particles 9 developing container 11 pick-off baffle 13 mixing paddle wheel 16 replenishing and distributing means 17 measuring slit 19 intermediate transfer roll 21 fixed magnet

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Michael Jay. Del Gio United States New York 14620 Rochester Highlands Avenue 114 (72) Inventor Gerald Tee. Rioi USA New York 14580 Webster Hartsville Lane 292 (72) Inventor Susan Jay. Clemmer New York, USA 14580 Webster Autumn Circle 575 (72) Inventor Lucinda A .. Dietrick New York, USA 14450 Fairport Whitney Ridge Road 30 Apartment A-11 (72) Inventor Sheryl A. Hanslick USA New York 14580 Webster Gravel Road 917

Claims (1)

[Claims] 1. Developer particles comprising a toner comprising a resin, a pigment, charge additive particles and surface additive particles, and a carrier comprising a coated or uncoated or partially coated core. A magnetic stir zone development method comprising providing a development zone between a transport member having a rotating magnet for transporting the image and an imaging member, wherein the carrier has a zero magnetic field magnetization of less than about 10 emu / g. And the developer is conveyed to the photoconductive image forming member by the conveying member, and the toner adheres to the image on the image forming member to cause development, and the magnetic stirring zone developing method.