KR900001468B1 - Carrier of developer electrophoto-graphic copying machine - Google Patents

Abstract

The carrier for a developer has a composition of formula (MO)x(Fe2O3) y in which M is at least one metal selected from a group containing Li, Mn, Ni, Zn, Cd, Cu, Co, Mg. The composition has a bulk density of 1.8 - 3.4 g/cm3 and a magnetisation of 10 30 emu/g in a magnetic field of 450 - 1,000 Oe(oersted).

Description

Developer Carrier for Electrophotographic Copiers

1 is a graph showing the relationship between the developing electric field and the spatial frequency for the dielectric carrier and the conventional conductor carrier of the present invention.

2 is a graph showing the relationship between magnetic field strength and magnetization strength for a carrier of the present invention and a conventional carrier.

3 is a graph showing the good regeneration area of the blackish black portion.

4 is a graph showing the magnetization characteristics of a carrier different from the carrier of the present invention.

FIG. 5 is a graph showing the regeneration of the blackish black portion of the carrier with the magnetization properties shown in FIG.

The present invention relates to a developer for an electrophotographic copier, and more particularly to a carrier of a two-component developer for an electrophotographic copier.

As a carrier of the two-component developer for electrophotographic copiers, iron powder, ferrite powder, or the like has been used. The carrier has a resistivity of about 10 ¹⁶ dBm exhibiting conductive properties and a resistivity of about 10 ¹² dBm exhibiting dielectric properties.

When using a conductive carrier having a resistivity of about 10 ⁶ dBm, charge injection from the developing roll is carried out and the actual developing electric field becomes large, so that the light-free black portion can be developed with high strength. The term " solid black portion " means here the no-light black portion of the original being copied. In this case, however, undesirable white lines sometimes occur in the non-light black portions, resulting in poor reproduction of thin lines.

On the other hand, when using a dielectric carrier having a resistivity of about 10 ¹² dBm, the relationship between the developing electric field and the spatial frequency, that is, the number of lines / mm is shown in FIG. The maximum value of the developing electric field is in the strength region between 1.0 and 10 lines / mm, in which the fine line regeneration is excellent. But the field to develop is very weak. This is because charge injection from the developing roll is not performed in the light black portion, and a charge having a polarity opposite to that of the toner remains in the carrier on the surface of the dielectric developing layer after development. Therefore, the dielectric carrier has a drawback of a so-called peripheral effect so that the toner density at the center of the no-light black portion is significantly reduced compared to the edge portion.

It is an object of the present invention, in particular, to provide a carrier for a developer in which the reproducibility of the thin lines obtainable by the dielectric developer is maintained well.

It is another object of the present invention to provide a developer carrier for enhancing the toner density in the regeneration center of the opaque black region.

Another object of the present invention is to provide a carrier for a developer having a long life.

(에르스텟)의 자계내의 자화율이 10-30emu/g인 (MO)_X(Fe₂O₃)_Y로 표시되는 조성These and other objects and properties, advantages have a bulk density of 1.8-3.4 g / cm 3, 450-1000

The composition represented by (MO) _X (Fe ₂ O ₃ ) _Y having a susceptibility of 10-30 emu / g in the magnetic field of (ersted).

The above and other objects, features and advantages will be described in more detail with reference to the accompanying drawings.

(에르스텟)의 자계내의 자화률이 10-30emu/g인 (MO)_X(Fe₂O₃)_Y로 표시되는 조성물로 구성된 현상제의 캐리어에 의해 달성된다. 이 경우에, M은 리듐, 망간, 니켈, 아연, 카드뮴, 구리, 코발트 및 마그네슘을 포함하는 그룹으로부터 선택되는 최소한 하나의 금속이다. 상기 목적은 상기 조성물이 수지로 피복되어 구성된 현상제의 캐리어에 의해 역시 달성될 수 있다.The above-mentioned object of the present invention is a bulk density of 1.8-3.4 g / cm 3 And 450-1000

(MO) The susceptibility in the magnetic field of (Eersted) is 10-30 emu / g_X(Fe₂O₃)_YIt is achieved by a carrier of a developer composed of a composition represented by. In this case, M is at least one metal selected from the group comprising lithium, manganese, nickel, zinc, cadmium, copper, cobalt and magnesium. This object can also be achieved by a carrier of a developer in which the composition is covered with a resin.

2 to 5, an embodiment of the present invention has been described. 2 is a diagram illustrating magnetization characteristics of various types of carriers. In FIG. 2, a represents magnetization characteristics of a conventional iron oxide powder and b represents magnetization characteristics of a conventional ferrite carrier.

In the case of using powdered iron oxide having magnetization properties shown by curve a in FIG. . In addition, the inverted electric charge is held on the carrier on the surface of the developer layer as described above, so that the magnetic field for development is weakened, thereby preventing the generation of high density radiant images. It is possible to increase the density of the radiated image by increasing the rotational speed of the developing roll. However, the toner images formed on the photodetector carry carry strongly connected to each other.

The reproducibility of the blackish black portion in the radiated image produced by the developing apparatus using the magnetic brush has been studied in connection with the present invention. In the developing apparatus, the developer used includes a toner mixed with a carrier containing ferrite as a main component. Regeneration of the no-black part has also been studied in connection with carriers with different magnetization properties. As a result, it was found that the good reproducibility of the no-light black portion can be obtained by the property indicated by the hatched area in FIG.

범위의 세기를 가진 자계 및 10-30emu/g 범위의 자화 강도에 의해 규정된다. 캐리어의 자계 강도가 10emu/g이하일때, 광 감지체상에 위치하는 캐러어의 양이 증가하면 토너 밀도는 불충분하게 된다. 제2도에서의 캐리어의 자화 특성 곡선 c 및 d는 제3도에서의 c'및 d' 포인트와 각각 대응한다.The area of FIG. 3 is 450-1000

It is defined by the magnetic field with intensity in the range and the magnetization strength in the range 10-30emu / g. When the magnetic field strength of the carrier is 10 emu / g or less, the toner density becomes insufficient if the amount of carriers placed on the photosensitive member increases. The magnetization characteristic curves c and d of the carrier in FIG. 2 correspond to the c 'and d' points in FIG. 3, respectively.

According to the carrier of the present invention having the magnetization properties shown by curves c and d in FIG. 2, the bonding force is weakened by the magnetic field affecting between the carriers, so that the developer on the developing roll easily moves in the thickness direction of the developing layer. do. The toner located inside the developing layer is used for developing. It is possible to quickly remove the charge remaining on the carrier on the surface of the developing layer from the toner, and to remove the toner together with the carrier from the surface of the photosensitive body. As a result, an appropriate radiation image having a high density can be obtained without weakening the developing electric field. The binding force acting between the carriers is not strong enough to cause the above-mentioned deterioration, so

의 자계 강도에서 자화 강도 10-30emu/g의 자화 강도를 가진 캐리어를 사용한 본 발명으로부터 유도되는 또다른 장점은 현상제의 수명이 현저히 증가하는 것이다. 토너 및 캐리어의 두 성분으로 구성되는 현상제의 수명은, 토너 또는 토너에 포함된 첨가제가 캐리어 입자의 표면에 달라붙어 캐리어의 전기 전하의 충전 용량을 감소시키기 때문에 짧아진다. 자계에 의해 캐리어 사이에 작용하는 결합력이 커질수록, 캐리어의 표면에 부착되는 첨가제는 더욱 증가한다.450-1000

Another advantage derived from the present invention using a carrier having a magnetization strength of 10-30 emu / g at a magnetic field strength of is a significant increase in the lifetime of the developer. The lifetime of the developer consisting of two components, the toner and the carrier, is shortened because the toner or the additive contained in the toner clings to the surface of the carrier particles to reduce the charge capacity of the electric charge of the carrier. The greater the bonding force acting between the carriers by the magnetic field, the more additives are attached to the surface of the carrier.

According to the carrier with the weak bonding force acting between the carriers, the toner or additives adhering to the carrier surface is significantly reduced. The life of the developer is extended by about 10 times the life of the conventional carrier powder composed of iron oxide.

의 자계에서 자화 강도 10-30emu/g 범위는 캐리어 조성물을 선택함으로 얻어질 수 있다. 1.8g/㎤-3.4g/㎤ 범위내에서 캐리어의 벌크 밀도(A, D)를 설정하는 것이 바람직하다. 왜냐하면 캐리어가 과다한 다공으로 구성되어 있으면, 캐리어의 기계적 강도는 바람직하지 못하게 감소되기 때문이다. 또, 수지로 피복된 캐리어를 사용하는 경우에, 캐리어를 수지로 피복시키기가 어렵다. 왜냐하면 수지가 다공성 캐리어를 통해 스며들기 때문이다. 반면에, 벌크 밀도가 과도하게 크면, 캐리어는 파괴되기 쉬우며 현상 기계는 바람직하지 못한 큰 토오크를 가져야 한다.450-1000

The magnetization strength in the range of 10-30 emu / g in the magnetic field of can be obtained by selecting the carrier composition. 1.8g / cm 3 -3.4g / cm 3 It is preferable to set the bulk density (A, D) of the carrier within the range. This is because if the carrier is made up of excessive porosity, the mechanical strength of the carrier is undesirably reduced. Moreover, when using the carrier coated with resin, it is difficult to coat the carrier with resin. This is because the resin seeps through the porous carrier. On the other hand, if the bulk density is excessively large, the carriers are susceptible to breakage and the developing machine should have an undesirable large torque.

범위일때 10-30emu/g 범위의 자화 강도가 현상 롤상에서 유지될 수 있도록 몰비 X/Y는 0.85이하가 되어야 한다.When the molar ratio X / Y in the (MO) _X (Fe ₂ O ₃ ) _Y structural formula reaches 0.85 to 1, magnetization tends to be large. Magnetic field strength is 450-1000

In the range, the molar ratio X / Y should be less than 0.85 so that the magnetization strength in the range of 10-30 emu / g can be maintained on the developing roll.

The carrier of the present invention is preferably composed of (CuO) 0.15-04, (ZnO) 0-0.2 and (Fe ₂ O ₃ ) 0.6-0.7. Selected values for the bulk density of the carrier can be obtained by performing a final heat treatment at about 1000 ° C. to remove bubbles in the carrier particles.

The carrier is made by combining (Fe ₂ O ₃ ) and (MO), and the molar ratio X / Y is 0.85 or less. The mixture is now ground and mixed for at least one hour using a wet ball mill or a wet vibrating ball mill. The slurry thus obtained is dried, powdered and calcined at a temperature of 700-1200 ° C. The calcareous product is composed of fine particles of size up to 20 μm, suitably up to 5 μm.

The particles thus formed are maintained at a temperature of 100-1500 ° C. for 1-24 hours. The sintered product can be further reduced and the surface of the product can be reoxidized at low temperatures if necessary. The required resistivity of the carrier can be obtained by coating the carrier with styrene resin, fluororesin or the like. In this case, it is selected to match the toner used for the water used for coating.

The above-described manufacturing method can produce an ideal carrier for a developer. The above-mentioned manufacturing method is described by way of example only, and the present invention is not limited to the above-mentioned manufacturing method.

According to a particular embodiment of the carrier of the present invention, the carrier may be created as follows.

EXAMPLE

0.23 mol% CuO, 0.07 mol% ZnO, 0.7 mol% Fe ₂ O ₃ is made into powder,

일 때 자화 강도는 33emu/g이다. 자계 강도가 500

일 때 자계 강도는 20emu/g이다. 캐리어의 벌크 밀도는 2.4g/㎤이다.The carrier has a magnetization characteristic as shown by curve f in FIG. 4 and has a magnetic field strength of 1000

The magnetization strength when is 33emu / g. Magnetic field strength of 500

When the magnetic field strength is 20emu / g. The bulk density of the carrier is 2.4 g / cm 3.

According to a copy test using a two-component developer consisting of a toner and a carrier, and a conventional magnetization brush developing apparatus, an original image having a light gray black portion having a gray density of 0.7 has an image density of 1.1 even at the center of the light black portion. Copied.

의 자계에서 자화 강도가 각각 10emu/g 및 300emu/g인 캐리어의 자화 특성을 나타낸다. 곡선 h및 i는 유사한 자계에서 40emu/g 및 50emu/g의 자화 강도를 각각 나타낸다.Several carriers with different magnetization characteristic curves as shown in FIG. 4 were similarly tested. Curves e and g are 500

In the magnetic field of, the magnetization strengths of the carriers of 10 emu / g and 300 emu / g, respectively. Curves h and i show magnetization intensities of 40 emu / g and 50 emu / g, respectively, in similar magnetic fields.

According to the test result, the curves e and g can obtain good radiation capability of the light black part as shown in FIG. The carriers shown by curves h and i have insufficient radiation capacity at points h and i. The dotted line shown in FIG. 5 represents the boundary between the poor radiation condition and the good radiation condition for the light black part.

Radiation tests comparing the life of the present invention and the carrier of the prior art were continued. The lifetime of a conventional carrier with iron oxide is about 20,000 copies per kilogram of toner.

As described above, the radiation ability of the thin lines provided in the dielectric developer is maintained at a high level by the developer of the present invention. In addition, the toner density of the light black portion is increased and the life of the developer is significantly increased as compared to the developer of the prior art.

Although suitable embodiments of the present invention have been described above, it is to be understood that the preferred embodiments of the present invention described above may be changed or modified without departing from the spirit and scope of the appended claims.

Claims (7)

450-1000

Consisting of a composition represented by (MO) _X (Fe ₂ O ₃ ) _Y with a bulk density of 1.8-3.4 g / cm 3 and susceptibility 10-30 emu / g in the magnetic field of (ersted), where M is lithium, manganese, nickel And at least one metal selected from the group consisting of zinc, cadmium, copper, cobalt and magnesium. The carrier of claim 1, wherein the carrier is composed of (CuO) 0.15-0.4, (ZnO) 0-0.2, and (Fe ₂ O ₃ ) 0.6-0.7. The carrier for a developer according to claim 1, wherein the carrier is formed by coating the composition with a resin. The carrier for a developer according to claim 3, wherein the resin is a styrene resin. The carrier for a developer according to claim 3, wherein the resin is a fluoro resin. The carrier for a developer according to claim 1, wherein the molar ratio X / Y is 0.85 or less. A developer having a mixture of toner and a carrier for toner, the carrier having a magnetic field of 450-1000

Composed of a composition represented by (MO) _X (Fe ₂ O ₃ ) _Y having a susceptibility of 10-30 emu / g and a bulk density of 1.8-3.4 g / cm 3 in (ersted), where M is lithium, manganese, nickel, A developer, characterized in that at least one metal selected from the group consisting of zinc, cadmium, copper, cobalt and magnesium.

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