JPS6032062A - Developing method - Google Patents

Abstract

PURPOSE:To obtain efficient developing property without blocking by carrying magnetic toner containing iron oxide of specific quantity or more in the same direction as the moving direction of the surface of a picture carrier. CONSTITUTION:The magnetic toner 9 adsorbed to the surface of a non-magnetic sleeve 3 is carried in the arrow S direction by the relative rotation between the non-magnetic sleeve 3 and a magnetic member 6. The magnetic toner 9 passing through a doctor gap (d) is contacted with the surface of a photosensitive drum 1 near a developing gap D and adhered to the surface to form a toner image. Although the carrying speed of the toner 9 is set up to a high speed as possible, the speed should be 1.1 times or less the perpheral speed of the surface of the photosensitive drum 1. Efficient developing property is obtained by setting up the content of magnetic powder in the toner 9 to 60wt% or more. If the content exceeds 80wt%, fixing property is extremely deteriorated.

Description

[Detailed Description of the Invention] [Technical Field] This invention develops an electrostatic charge image formed on the surface of an image carrier using a one-component heat-fixing magnetic toner (visualized by a magnetic brush method). Regarding the method.

[Prior art] As a copying method using electrophotography, for example, an electrostatic charge image is formed on various photoreceptors such as a Se photoreceptor, a 7"10 photoreceptor, an organic photoconductor, etc., and a magnetic developer is used to develop the image. It is generally known to develop the image by a brush method and then fix it, or to transfer the developed image onto a transfer sheet 1 such as plain paper and then fix it to obtain the final image.

The magnetic developer used in this copying method is generally a two-component developer, which is a mixed powder of non-magnetic toner in which various additives such as colorants and dyes are dispersed in a magnetic carrier and fixing resin. be. However, when using this two-component developer, it is necessary to provide the developing device with a means to keep the toner concentration in the developer constant and a means to uniformly stir and mix the toner and carrier. There is a problem in that devices are becoming larger and more complex. In addition, if the sharp particles continue to be mixed with toner for a long time, a toner film will be formed on the surface of the carrier particles, which will deteriorate the carrier's friction and friction charging properties, so the carrier should be replaced regularly. -I need to do it.

Therefore, it has been proposed to use carrier particles as a magnetic developer to develop electrostatic images using a one-component magnetic developer mainly consisting of resin and magnetic powder (for example, in Japanese Patent Application Laid-Open No.
49-4532), it was first put into practical use using treated paper such as zinc oxide paper or electrostatic recording paper, and then directly reviewed after development, followed by electrophotographic copying that included the transfer process described in Moe. It has also been put into practical use as a method.

In the copying method that includes this transfer process, °C is the image quality,
In particular, from the viewpoint of fixing properties, magnetic toner with a low magnetic powder content (approximately 40% by weight or less) and a magnetic toner (for example, Japanese Patent Application Laid-Open No. 1983-1999-1)
66455) is often used. However, in order to perform good development using such a low-magnetic toner, the transport speed of the magnetic toner is set to be at least twice the moving speed of the photoreceptor surface. Therefore, high pressure is applied when the magnetic toner passes through the doctor blade. Therefore, there is a problem that blocking is likely to occur.

[Objective] An object of the present invention is to provide a developing method that eliminates the problems of the prior art described above and provides good developability without blocking.

[Summary] The developing method of the present invention includes installing a non-magnetic sleeve that holds a permanent magnet member having a plurality of magnetic poles therein, facing the surface of an image carrier that moves in a predetermined direction and holds an electrostatic image. A magnetic toner mainly composed of thermoplastic resin and magnetic powder is supplied onto the non-magnetic sleeve, and the magnetic toner is brought into contact with the surface of the image carrier by relative rotation between the permanent magnet member and the non-magnetic sleeve. A developing method in which the electrostatic charge image is visualized by conveying the magnetic toner toward a gap opposite to a magnetic sleeve and selectively adhering the magnetic toner to the surface of the image carrier in the gap, wherein iron oxide is used as the magnetic toner. using a magnetic toner containing 60% by weight or more of It is characterized by being conveyed at a speed of .1 times or more -F.

[Configuration] [Effect] The details of the present invention will be explained below with reference to the drawings.

FIG. 1 is a sectional view showing an example of a developing device for carrying out the present invention.

In the figure, reference numeral 1 denotes a photoreceptor drum holding an electrostatic charge (indicated by a + symbol in the figure) on its surface, which moves in the direction of arrow 1 in the figure. A developing device 2 is installed around the photoreceptor drum (the developing device 2 is placed opposite the surface of the photoreceptor drum 1 with a gap (hereinafter referred to as a developing gear) 1). A permanent magnet member 6 consisting of a magnetic slave 3 and a permanent magnet 4 having a plurality of magnetic poles on its surface fixed to a shaft 5.
, the doctor blade 7 is arranged to maintain a gap (hereinafter referred to as doctor gap) d between it and the non-magnetic sleeve 3.
, l# with toner Ia8 containing magnetic toner 9.

According to the above-described developing device, the magnetic toner 9 attracted to the non-magnetic sleeve 3 is conveyed in the direction of the arrow S in the figure by the relative rotation of the non-magnetic sleeve 3 and the permanent magnet member 6. After passing through the doctor ear d, the magnetic toner 9 comes into contact with the surface of the photoreceptor drum 1 near the development gap D (=J) and adheres thereto, forming a toner image 10.The magnetic toner 9 after passing through the development gap D (The toner 9 is conveyed in the direction of the arrow S shown in the figure and collected in the toner tank 8.Then, the toner image 10 is transferred onto a transfer sheet (not shown) by a transfer means (not shown) such as a corona transfer device. After being transferred, a final image is obtained via a fixing means (not shown).

The inventors of the present invention have investigated the conditions under which good development can be carried out without blocking using the developing apparatus shown in FIG. 1, and have found several conditions.

First, if the conveyance speed of the magnetic toner is too fast, the magnetic toner is likely to be hit by strong horns as it passes through the doctor gap, making it more likely that blocking will occur. In order to prevent this, it is necessary to reduce the number of rotations of the non-magnetic sleeve as much as possible. However, if the number of rotations of the non-magnetic sleeve is reduced, the force for conveying the magnetic toner is weakened, resulting in a decrease in developing performance.

Therefore, in order to compensate for the decrease in developability, it is necessary to rotate the permanent magnet member in the same direction as the non-magnetic sleeve. Rotating the non-magnetic sleeve in the same direction as the permanent magnet member is described in, for example, Japanese Patent Application Laid-Open No. 55-126266-C.
However, studies conducted by the present inventors have confirmed that this toner transport method is extremely effective in preventing blocking.

Also, in order to prevent blocking, the toner transport speed V□ expressed by the following formula needs to be as fast as possible,
In particular, it is most preferable that V = 0, but it is sufficient if it is 1.1 times or less of the circumferential speed of the surface of the photoreceptor drum, 1ffi Vp.

D: Outside diameter of non-magnetic sleeve (mm) 1) Toner thickness on sleeve + nm) P: Number of magnetic poles of permanent magnet 11,: Number of rotations of non-magnetic sleeve (r, p, 13)
t16: Number of revolutions of permanent 11 stones (r, p, m, )
In addition, in order to slow down the toner transport speed and obtain good development performance, it is necessary to increase the movement of the magnetic toner on the non-magnetic sleeve to increase the chances of the magnetic 1 hener coming into contact with the photoreceptor surface. Yes, by increasing the magnetic force of the permanent magnet member, specifically in the range of 700 to 1700G on Three 1, and by increasing the number of rotations of the permanent magnet member.
1000r, p, m, or more (outer diameter 29.3111111
In the case of φ), it is preferable to increase the number of magnetic poles.

Next, when carrying out the above-mentioned one henna one conveyance method, the composition of the magnetic toner is also an important factor.

In other words, according to the above-described toner conveying method, the magnetic toner on the non-magnetic sleeve does not follow the rotation of the non-magnetic sleeve;
As the permanent magnet member rotates, it receives a force in the opposite direction to the non-magnetic sleeve, so if the content of magnetic powder in the toner is low, the movement of the magnetic toner on the non-magnetic sleeve will be reduced. As a result of studies conducted by the present inventor, the content of magnetic powder in the toner should be 60% by weight or more (preferably 70% by weight or more).
It has been found that good developability can be achieved by using the following formula. However, if the content of magnetic powder exceeds 80% by weight, the fixing properties will be extremely reduced, so it is necessary to exceed 80% by weight.

Examples of magnetic powder include powders of metals such as iron, nickel, chromium, and cobalt, and alloys thereof. Yes, Noelai 1-
Alternatively, various substances exhibiting ferromagnetism such as hematite (γ-Fe 203 ) and magnetite (Fe203 and/or Fe304) are known, but it is necessary to use hematite or magnetite from the viewpoint of magnetic properties and hue. Of the magnetic properties, saturation magnetization (4πIs) is proportional to the content of magnetic powder, but a range of 50 to 72 ellllj/(+ is appropriate).On the other hand, coercive force (zi-IC) is determined depending on the type of magnetic powder. , if the J is too low, blocking will easily occur, while if the J is too high, the proportion occupied by sword-shaped particles will increase, and the volume of magnetite will increase, so 80.
-4000e (preferably 100-3000e) is suitable.

The fixing resin needs to be appropriately selected depending on the fixing method. In the case where the equation 54.n is a heating A = Bun type, or in the case of a heat roll type such as a heat roll, the following thermoplastic resins are used, for example. Styrenes, vinyl esters, Nisdels of α-methylene aliphatic monocarboxylic acids, acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers, vinyl ketones, N
- Pomopolymers obtained by polymerizing monomers such as vinyl compounds, copolymers obtained by copolymerizing two or more of these monomers, or mixtures thereof may be used. In addition, non-vinyl resins such as non-vinyl thermoplastic resins such as rosin-modified phenol-formalin resin, bisphenol-type epoxy resin, oil-modified 1-box resin, polyurethane resin, lerulose resin, polyneedle resin, and polynisdel 4'tJ resin, or A mixture of the above-mentioned vinyl resin and the above-mentioned vinyl resin can also be used.

In particular, when fixing the developed toner image by heating in an oven, a sphenol-based epoxy resin is preferable.
In the case of fixing using a hot roll, a resin whose main component is a styrene resin, or a Borier or Stell resin is desirable. The greater the styrene component of the styrene resin, the better the mold releasability against hot rolls. Further, Ic, which further improves the releasability from hot rolls, includes fatty acid metal salts, low molecular weight polyethylene, polypropylene, and carbon atoms of 28 or more. It is effective to add higher fatty acids, natural or synthetic paraffins, etc.

The magnetic toner used in the present invention contains the above-mentioned magnetic powder and resin as essential components, and optionally includes a resistance modifier such as carbon black, a fluidity modifier such as 5i02 particles, nigrosine dye and metal-containing azo dye. may contain various additives such as charge control agents such as (for example, see Japanese Patent Application Laid-Open No. 57-97545@), and can be manufactured using these materials by known methods such as pulverization or spray drying ( can be done.

The magnetic toner thus obtained is directly determined after development:
It can be applied to either the so-called CPC method in which the toner is transferred after development, or the so-called P'PC method in which it is transferred after development and then fixed.Especially when it is applied to the PPC method, the volume of the magnetic toner is limited from the viewpoint of transferability. The resistance is preferably 108 Ω・C11 or more, and when transferring to plain paper, it is 10 Ω・0.
m or more is better. Also, regarding the toner order, 5 to 50
It is sufficient that the thickness is within the range of 5 to 30 μm, especially when the layer is used in a PPC system.

In addition, in the present invention, the resistance of the toner is determined by placing 1 to 10 toner powders in a Teflon (trade name) cylinder with an inner diameter of 3.05 mmφ.
The value is measured under a load of 100 (Jr) and an electric field of 4000 v/am. was evaluated as follows. First, the blocking property was evaluated using a non-magnetic cylindrical hermetic container with one end sealed (outer diameter 60 m1 Ilφ, inner diameter 5811 mφ, length 1
0100Il1 is stood upright, and after filling the inside with 1ooor of magnetic toner, the other end is sealed with a lid.Then, the cylindrical container is vibrated up and down for 2 minutes at a frequency of 20 times/min and an amplitude of 2II1m, and the vibrations are measured before and after vibration. The aggregation state of the toner was observed and evaluated. Storage stability at high temperatures was evaluated by leaving the magnetic toner on a Petri dish at a temperature of 55° C. for 100 hours.

[Example 1] Acrylic to styrene resin (weight average molecule 11 i!io
o.

00, number average molecule m 200000)...25
Part by weight: Polypropylene (molecular weight: 3000, Viscol 550P manufactured by Sanyo Chemical Co., Ltd.)...Triple part: Magnetite (RB-81, ll-1c 180 0e)
) A total of 100 buns The above composition was mixed in a heating kneader for 30 minutes, and then cooled and solidified. The cooled solidified product is pulverized into particles of 30 μm or less using a jet mill, 0.05 parts by weight of a fluidity modifier (carbon black) is added to the pulverized powder, mixed, and then classified to obtain particles with a particle size of 5 to 20 μm. (with 17, the volume resistance is 1×
A magnetic toner of 10 Ω·C11 l was obtained.

Using the above magnetic toner, an experimental copying machine equipped with the developing device shown in FIG.
Image planning was performed under zero environmental conditions. In this case, a Se drum having an outer diameter of 120+n+aφ was used as the photosensitive drum 1 and rotated at a circumferential speed of 100 mm/sea. In addition, the non-magnetic sleeve 3 (a stainless steel cylinder with an outer diameter of 31.4 ml and 1φ) is rotated in the direction of arrow X shown in the figure.
, p, i+, and rotate the permanent magnet member 6 (outer diameter 29.
3mm+φ, 8-pole symmetrical magnetization, magnetic flux density on the sleeve is 8
300 Ba-ferrite magnet fixed to the shaft)
was rotated at 150 Or, p, to, in the same direction as the sleeve. Also, the developing gear 11 lug D and the doctor gap d
were adjusted to 0.34 mm and 0.2411 Illl, respectively. Xerox paper was used as the transfer paper, and the fixing was carried out by a heat roll fixing machine having a fixing roll covered with Deflon (trade name) heated to 170°C and a pressure roll made of silicone rubber. is 63II
lllll/SeC.

As a result, the resolution is 8 lines / III 111, and the resolution is 1
．． 26 and high quality images with good halftone reproducibility were obtained. Further, the above magnetic toner did not cause any problems in terms of blocking properties and storage stability.

[Comparative Example 1] The blending amounts of 7dylene-acrylic resin and magnetite were
A magnetic toner was prepared under the same conditions as in Example 1 except that the amounts were 47 parts by weight and 50 parts by weight, respectively. Using this magnetic toner, the -C1 permanent magnet member was kept stationary and the non-magnetic sleeve was rotated at 122 r, p=i- (V7=200.
Image evaluation was performed under the same conditions as in Example 1 except for
Book/mi+ was not satisfactory.

1 Example 21 Styrene-〇-butyl methacrylate (number average molecular weight 2
0000, weight i) average molecule m 220000)...
・20 parts by weight polynismil resin (PS#2 manufactured by Hitachi Chemical)...7
Weight part polypropylene (Sanyo Chemical Co., Ltd. Goskoal 550P)...
...3 parts by weight of magnetite (E P T 500 manufactured by Toda Kogyo, ■HC
The above composition was kneaded for 30 minutes using a two-roll heating mixer, and then cooled and solidified. Cooled solidified product in jet mill 3
Grind into particles of 0 μm or less, add 0.08 parts by weight of a fluidity modifier (carbon black) to the pulverized powder, mix, and classify to obtain particles with a particle size distribution of 5 to 20 μm (with a volume resistance of 5
A magnetic toner of ×100·eta was obtained.

Using the above magnetic toner as a ζ permanent magnet and using an S'-ferrite magnet with a magnetic flux density of 9400 on the sleeve,
Permanent magnet member and non-magnetic sleeve each 1000r,
Rotate by p, i, and 60 r, Fl, lll (
Vl-=40 mm/sec), and the same conditions as in Example 1 except that the circumferential speed of the 3e drum was 60 o+i/sec.

When we conducted an image evaluation, we found that the resolution was 8 lines/ml11
A high-quality image with a 1-peta density of 1.43 and good halftone reproducibility was obtained.

Further, the above magnetic toner did not cause any problems in terms of blocking properties and storage stability.

[Comparative Example 2] A magnetic toner was prepared under the same conditions as in Example 1, except that the amounts of styrene-〇-butyl methacrylate and magnetite were 40 parts by weight and 50 parts by weight, respectively.

Using this magnetic toner, the permanent magnet member was kept stationary and the non-magnetic sleeve was rotated at 61 r, l), I (Vy
= 100.3111/See) When image evaluation was performed under the same conditions as in Example 1, the density was 0.86,
The resolution was 5.6 lines/Ill, which was not satisfactory.

[Effects] As described above, according to the present invention, high-quality images can be obtained without blocking.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of an apparatus for carrying out the developing method of the present invention. Sleeve, 6: Permanent magnet member, 9: Magnetic toner first
figure

Claims (1)

[Claims] 1. Reinstall the non-magnetic sleeve that moves in a predetermined direction and holds therein a permanent magnet part having a plurality of polar magnets facing the surface of the image carrier that holds the electrostatic charge image; A magnetic toner mainly composed of thermoplastic resin and magnetic powder is supplied onto the sleeve, and the magnetic toner is transferred between the image carrier surface and the non-magnetic sleeve by relative rotation between the permanent magnet 6 and the non-magnetic sleeve. The -CiIil magnetic toner is conveyed toward the opposing gap of the -CiIil in the opposing gap.
In the developing method in which the electrostatic charge image is visualized by selectively exposing the surface of the image carrier, a magnetic toner containing 60% or more of iron oxide is used as the magnetic toner, and the opposing gap is The magnetic toner is moved in the same direction as the moving direction of the image carrier surface and at a speed of 1.0% of the moving speed of the image carrier surface.
It is characterized by being conveyed at a speed of 1 times or less. a-image method.