JPH0635234A - Developing method - Google Patents

Abstract

PURPOSE:To provide the developing method by which a satisfactory picture quality is obtained even when plain paper is used, by a simple constitution. CONSTITUTION:In the developing method for developing a toner image on the surface of an image carrier 1 by radiating an optical signal from the back of the image carrier 1 by providing the image carrier 1 consisting of an optical semiconductor material of transparency, and a developing roll 5 for forming a magnetic brush, this method uses the image carrier 1 formed in positive chargeability, and a magnetic developer obtained by mixing a positive chargeability toner formed in 10<2>-10<8>OMEGA.cm volume specific resistance, and 5-20mum average particle diameter, and a negative chargeability magnetic particle formed in 10<3>-10<12>OMEGA.cm volume specific resistance, and 10-100mum average particle diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic developer which is irradiated with an optical signal from the back surface of an image carrier made of an optical semiconductor material having a light-transmitting property and which is conveyed by a developing roll composed of a permanent magnet member and a sleeve. The present invention relates to a developing method for selectively adhering toner therein.

[0002]

2. Description of the Related Art Conventionally, as a means for reproducing information such as a document or a figure, means such as electrophotography, electrostatic recording or electrostatic printing has been generally used. For example, in an electrophotographic copying machine or a facsimile, a toner in which an electrostatic latent image is formed on a photoconductor layer or a dielectric layer and then charged to a predetermined polarity by frictional charging with a carrier by a magnetic brush method, Alternatively, an image forming method is often adopted in which a magnetic toner containing a binder resin and magnetic powder as main components is selectively adhered to the latent image to obtain a reproduced image. However, when such an image forming method is adopted, an electrostatic latent image forming means including a charging means for uniformly charging the image carrier in advance is provided separately from the developing means in the image forming apparatus. Since it is necessary, there is a problem that the device becomes complicated and tends to increase in size.

Therefore, as disclosed in, for example, Japanese Patent Publication No. 55-30228, a magnetic toner having conductivity is magnetically adsorbed and held on a sleeve made of a non-magnetic conductive material, and the sleeve is opposed to the sleeve. An information signal is applied to the recording electrode while passing a sheet-shaped recording member between the recording electrode and the recording electrode, and electrostatic force is applied to the magnetic toner, and this magnetic toner is selectively adhered to the recording member. There is a suggestion to do so.

In addition to the above, many proposals have been made for the direct recording means. However, in all of them, the recording member is passed between the recording electrode and the counter electrode to perform the recording only by the electric means. Therefore, in order to obtain a good recorded image, it is necessary to strictly select various conditions such as the gap between the electrodes and the amount of toner supplied onto the recording member. Furthermore, when plain paper is used as the recording member, the surface resistance of the paper is greatly affected by environmental conditions such as humidity and temperature.Therefore, it is necessary to adjust the developing conditions according to these environmental conditions, There are problems such as not being able to record,
It has not been put to practical use yet.

On the other hand, an optical signal corresponding to the original image is radiated from the back surface of the image carrier made of an optical semiconductor material having translucency,
An image in which conductive magnetic toner conveyed by a developing roll including a permanent magnet member and a sleeve is selectively adhered to the surface of an image carrier to perform development, and the reproduced image is transferred and fixed on the surface of the recording member. Forming methods have also been proposed.

[0006]

The above-mentioned rear exposure method
In the image forming method, the volume resistivity value is, for example, 10
^Four-10¹²A so-called medium resistance magnetic toner of Ω · cm is used.
The developability is good, but the transfer efficiency of the reproduced image is high.
There is a problem that it is low. In other words, most as a transfer means
Even if the common corotron method is used, the reproduced image
The image is not completely transferred to the surface of the recording member, causing so-called transfer blur.
Image quality is degraded. For this reason, plain paper is used as the recording member.
Has the disadvantage that it cannot be used.

On the other hand, it is conceivable to uniformly charge the recording member in advance in order to improve the transfer efficiency. However, since this complicates the image forming apparatus, it has been required in recent years to make the apparatus compact, It is not preferable because it cannot meet the needs of price reduction. It should be noted that means for using recording paper which has been subjected to surface treatment in advance in order to improve transfer efficiency leads to an increase in paper cost and is unsuitable for this kind of apparatus for processing and recording a large amount of information. Therefore, even when plain paper is used, it is desired to develop a developing method having high transfer efficiency and capable of forming a high quality reproduced image.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems existing in the prior art and to provide a developing method having a simple structure and capable of obtaining a reproduced image of good quality even when plain paper is used. To do.

[0009]

In order to achieve the above object, in the present invention, an image carrier made of a light-transmitting optical semiconductor material is movably provided and a plurality of magnetic poles are provided on the surface. A hollow cylindrical sleeve made of a non-magnetic material and having a built-in permanent magnet member is provided so as to face the surface of the image carrier, and the magnetic developer supplied onto the sleeve is rotated relative to the sleeve and the permanent magnet member. The recording medium is conveyed to a recording area formed between the sleeve and the image carrier by means of an optical signal corresponding to the original image from the back surface of the image carrier to irradiate the surface of the image carrier with the magnetic developer. In the developing method for selectively adhering the toner, the image carrier formed to have a positive charging property and the volume resistivity of 10 ² to 10 ⁸ Ω.
cm, an average particle diameter of 5 to 20 μm, a positively chargeable toner, and a volume resistivity of 10 ³ to 10 ¹² Ω · cm, an average particle diameter of 10 to 1
The technical means of using a magnetic developer prepared by mixing negatively chargeable magnetic particles formed to have a diameter of 00 μm was adopted.

The positively chargeable toner constituting the magnetic developer used in the present invention has an average particle size of 5 to 20 .mu.m, preferably 6 to 16 .mu.m. It is not preferable because scattering occurs. On the other hand, if the particle size is large, the resolution and developability are lowered, which is inconvenient.

Next, the average particle size of the negatively chargeable magnetic particles is 10
.About.100 .mu.m, preferably 30 to 70 .mu.m, and larger in particle size than the positively chargeable toner. If the particle size is small, it tends to adhere to the image carrier, which is not preferable. On the other hand, when the particle size is large, it is necessary to more strictly control the toner density in the case of using a magnetic developer, and the surface of the image carrier is easily scratched, which is inconvenient.

If the volume resistivity of the positively chargeable toner is less than 10 ² Ω · cm, the conductivity is too high.
The charge injected into the toner is lost, the developability is lowered, and the background fog is generated, which is not preferable. On the other hand, if the volume resistivity exceeds 10 ⁸ Ω · cm, the magnetic field of the permanent magnet member increases the electric resistance of the toner chain formed on the sleeve, which makes it difficult to apply a bias voltage and reduces the developability. It is inconvenient.

[0013] On the other hand, if the volume resistivity of the negatively chargeable magnetic particles is less than 10 ³ Ω · cm, it is not preferable for breakdown at low voltage under the in positively chargeable toner exceeds 10 ¹² Ω · cm For the same reason as above, the charge injection effect becomes small, which is inconvenient.

In order to obtain the above volume resistivity value, for example, conductive particles such as carbon powder are added in an amount of 0.2 to 20.
It is desirable to contain it by weight%. The conductive particles can be added internally and / or externally to the toner.

Next, as the binder resin constituting the toner, the following ones can be used. When the fixing method is a heat fixing method (open or hot roll), for example, the following thermoplastic resins, that is, styrenes, vinyl esters, α-methylene aliphatic monocarboxylic acid esters, acrylonitrile, methacryloyl are used. A homopolymer obtained by polymerizing monomers such as nitrile, acrylamide, vinyl ethers, vinyl ketones and N-vinyl compounds, a copolymer obtained by copolymerizing two or more kinds of these monomers, or a mixture thereof is used. Can be used. Further, a non-vinyl type resin such as a non-vinyl type thermoplastic resin such as a bisphenol type epoxy resin, an oil modified epoxy resin, a polyurethane resin, a cellulose resin, a polyether resin or a polyester resin, or a vinyl type resin such as those described above. Can be used.

When the fixing system is the pressure fixing system, for example, the following pressure-sensitive resins, that is, higher fatty acids, higher fatty acid derivatives, higher fatty acid amides, waxes, rosin derivatives and alkyd resins are used. , Epoxy modified phenolic resin, Natural resin modified phenolic resin, Amino resin, Silicone resin, Urea resin, Acrylic acid or methacrylic acid and long chain alkyl methacrylate, Copolymerization oligomer of long chain alkyl acrylate, Polyolefin, Ethylene / vinyl acetate copolymer Examples thereof include a polymer, an ethylene / vinyl alkyl ether copolymer, and a maleic anhydride copolymer.

These resins can be arbitrarily selected and used by arbitrarily mixing them, but in order not to lower the fluidity when used as a toner, a resin having a glass transition point of higher than 40 ° C. or a resin mixture. Is effective.

The toner in the magnetic developer used in the present invention is not only a non-magnetic toner but also a magnetic powder made of a compound or alloy containing iron, such as ferrite or magnetite, or an element exhibiting ferromagnetism such as cobalt or nickel. A magnetic toner containing is also usable. The magnetic powder has an average particle size of 0.01 to 3 in order to be uniformly dispersed in the toner.
It is desirable that the thickness is formed to μm. The content may be in the range of 30 to 75% by weight.

Further, additives such as various pigments and dyes used in general dry developers may be contained as a component other than the above components, but the addition amount is 10% by weight or less so as not to deteriorate the fixing property. It is good to say

The above toner can be manufactured, for example, as follows. That is, the raw materials are first kneaded by heating, cooled and solidified, then pulverized, and then classified to obtain toner particles having a predetermined particle size. The conductive particles may be externally added to the surface of the toner particles, and the conductive particles may be fixed by a heat treatment, or the conductive particles may be internally added in the heating and kneading step, or the internal / external addition means may be used in combination. Good.

Next, as the magnetic particles constituting the magnetic developer, not only the particles made of the ferromagnetic material as described above,
A dispersion of these particles in a binder resin can also be used, but magnetite or ferrite particles are most suitable. The magnetic particles may be used as they are, but it is effective to provide a coating layer made of a resin material on the surface of the magnetic particles.

As the resin material for forming the coating layer,
It is preferable that the main component is a fluororesin having a hydrophilic functional group, for example, a carboxyl group and / or a hydroxyl group.
As the fluororesin, tetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, fluoroethylene propylene copolymer, ethylene tetrafluoroethylene copolymer, polychlorotrifluoroethylene, ethylene chlorotrifluoroethylene copolymer, fluoroethylene Copolymers and the like are known, and it is preferable to use a resin obtained by introducing a hydrophilic functional group such as a carboxyl group, a hydroxyl group, an amino group or an epoxy group into these fluororesins.

A hardener may be used in combination to firmly fix the fluororesin containing the hydrophilic functional group on the surface of the magnetic particles. Examples of such a curing agent include thermosetting compounds such as melamine and various amine salts.

Further, as a coating material, the adhesiveness with magnetic particles is improved, or the abrasion resistance is improved, the fusion of toner is prevented,
In addition to the above, a small amount of phenol resin, urea resin, alkyd resin, other filler, diluent, flexibility-imparting agent, etc. can be blended for the purpose of controlling toner chargeability and imparting fluidity to the developer. .

[0025]

FIG. 1 is a cross-sectional explanatory view of essential parts showing an example of a developing device used in the developing method of the present invention. In FIG. 1, reference numeral 1 denotes an image carrier, for example, a conductive layer 3 having a light transmitting property and an organic optical semiconductor material having a light transmitting property, or a on a surface of a support 2 made of a light transmitting material such as glass. -A photosensitive layer 4 made of a SiH film is applied to form a hollow cylindrical shape, and is provided so as to be rotatable clockwise, for example. The photosensitive layer 4
A protective layer made of a wear resistant material may be provided on the surface of the.

A developing roll 5 is provided at the end of a developer tank 7 containing the magnetic developer 6 and is provided so as to face the image carrier 1. The developing roll 5 is configured by coaxially combining a permanent magnet member 8 having a plurality of magnetic poles on the surface and a hollow cylindrical sleeve 9 made of a nonmagnetic material such as an aluminum alloy. By magnetic rotation, the magnetic developer 6 can be conveyed to the recording area 10 formed between the developing roll 5 and the image carrier 1. The sleeve 9 that constitutes the developing roller 5 is electrically connected to the bias voltage source 11.

Next, 12 is an optical signal irradiating means, which is provided on the back side of the image carrier 1 in the recording area 10 so as to irradiate the image carrier 1 with an optical signal corresponding to the original image. Reference numeral 13 denotes a transfer roll, which is provided so as to rotate in pressure contact with the surface of the image carrier 1.
Reference numeral 14 is a recording member, which is movable in the arrow direction,
It is possible to travel to a fixing unit (not shown) provided in the subsequent stage.

With the above structure, when the magnetic developer 6 is supplied to the recording area 10 by the developing roll 5, the magnetic developer 6 is formed.
Forms a so-called magnetic brush in the recording area 10, and this magnetic brush makes sliding contact with the surface of the image carrier 1 with a certain width. Therefore, it is possible to apply a charge or a potential due to frictional charging to the surface of the image carrier 1. Alternatively, a charging means such as a scorotron or a charging brush may be provided before development in order to stabilize the charge amount.

On the other hand, when an optical signal corresponding to the original image is emitted from the back surface of the image carrier 1 through the optical signal irradiating means 12, a portion of the surface of the image carrier 1 which is not irradiated with light and the developing roller 5 are irradiated.
There is no potential difference between the developing roller 5 and the developing roller 5, and the toner in the magnetic developer 6 adheres to that portion and is developed as a toner image. Next, the toner image is transferred to the image carrier 1 and the transfer roll 1.
3 is transferred onto the moving recording member 14 which is sandwiched between the recording member 14 and the recording member 14 and further fixed by the fixing means.

[0030]

EXAMPLES In the above-described developing method, as a result of an examination focusing on the characteristics of the toner and the magnetic particles constituting the magnetic developer, it was found that by setting the volume resistivity value to a specific range, the image density It was revealed that a high-quality image with good resolution was obtained. The results will be described below.

First, by mixing the following raw materials, a magnetic toner (A1) and a non-magnetic toner (A2) having a positive charging property,
And magnetic particles (B1) and (B2) having negative chargeability
And (B3) were prepared.

(A1) Positively chargeable magnetic toner Styrene-n-butylmethacrylate copolymer 27 parts by weight (Mn = 1.6 × 10 ⁴ , Mw = 21 × 10 ⁴ ) Magnetite 60 parts by weight (Toda Kogyo EPT500) Polypropylene 5 Parts by weight (Viscole 550P made by Sanyo Kasei) Positive charge control agent 3 parts by weight (Oil black BY made by Orient Chemical Co., Ltd.) 5 parts by weight carbon black (# 44 made by Mitsubishi Kasei) A kneader with a heating roller After kneading for 30 minutes, cooling and solidification, pulverization and classification are carried out to obtain a positively chargeable magnetic toner having an average particle size of 11 μm.
1 part by weight of carbon black (manufactured by Mitsubishi Kasei
44) was added and uniformly fixed on the surface of the magnetic toner.

(A2) Positively chargeable non-magnetic toner Styrene-n-butyl methacrylate copolymer 77 parts by weight (Mn = 1.6 × 10 ⁴ , Mw = 21 × 10 ⁴ ) Polypropylene 5 parts by weight (Viscole 550P manufactured by Sanyo Kasei Co., Ltd.) Positive charge control agent 3 parts by weight (Orient Chemical's Bontron S-31) Filler (CaCO ₃ ) 5 parts by weight (Nitto Koka Kogyo's MSK-C) Carbon black 10 parts by weight (Mitsubishi Kasei # 44) Above The blended raw materials were produced by the same means as in (A1) above.

(B1) Negatively charged magnetic particles Styrene-n-butyl methacrylate copolymer 30 parts by weight (Mn = 1.6 × 10 ⁴ , Mw = 21 × 10 ⁴ ) Magnetite 60 parts by weight (EPT500 manufactured by Toda Kogyo) Polypropylene 5 Parts by weight (Viscole 550P manufactured by Sanyo Kasei) 3 parts by weight of negatively chargeable charge control agent (Bontron E-81 manufactured by Orient Chemical Co., Ltd.) 2 parts by weight of carbon black (# 44 manufactured by Mitsubishi Kasei) Kneader with heating roller Kneading for 30 minutes, cooling and solidifying, crushing and classification to obtain negatively charged magnetic particles having an average particle size of 50 μm, and further 120
0.5 part by weight of carbon black (Mitsubishi Kasei # 4
4) was added and uniformly fixed on the surface of the magnetic particles.

(B2), (B3) Negatively chargeable magnetic particles Ba-Ni-Zn based ferrite carrier 100 parts by weight (Hitachi Metals KBN-100) Resin * (Hitachi Metals HM-40) 3 parts by weight Curing agent ( Melamine-formalin) 0.1 parts by weight * Mixture of 30% by weight of polyvinyl fluoride modified with a carboxyl group (acid value 20) and 70% by weight of styrene-acrylic resin A fluidized bed coating device is used with the above composition. Then 17
Heat treatment at 0 ° C for 30 minutes, crush and classify for 30 to 7
A resin-coated carrier of 0 μm was obtained. B2 uses the ferrite carrier as it is, and B3 uses carbon black (# 44 manufactured by Mitsubishi Kasei) on the resin-coated carrier.
0.5 wt% coating.

The positively chargeable toner prepared as described above and the negatively chargeable magnetic particles were mixed to form a magnetic developer having a toner concentration of 40%, and the result was developed under the conditions described below.
Shown in. The volume specific resistance values of the positively chargeable toner and the negatively chargeable magnetic particles shown in Table 1 are set to an appropriate amount (10 and several mg) of the sample.
Weigh it, fill it into a Teflon (trade name) cylinder with an inner diameter of 3.05 mm with an improved dial gauge, and load it under a load of 0.1 kg.
D. C. An electric field of 100 V / cm was applied and measured, and the resistance value was calculated. A Yokogawa Hewlett-Packard Model 4329 Insulation Resistance Tester was used to measure the resistance.

Next, development, transfer and fixing conditions will be described. First, the doctor gap that regulates the layer thickness of the magnetic developer 6 on the developing roll 5 was 0.3 mm, and the developing gap of the recording area 10 was 0.25 mm. Next, the developing roll 5 is S
A permanent magnet member 8 magnetized with 8 poles is incorporated in a sleeve 9 made of US304 and having an outer diameter of 20 mm, the surface magnetic flux density on the sleeve 9 is 700 G, and the rotation speed of the sleeve 9 is 150 r.p.
m.

The image carrier 1 was formed of a positively chargeable organic photo-semiconductor to have a diameter of 40 mm and a peripheral speed of 50 mm / sec.
On the other hand, a bias voltage of +350 V was applied to the sleeve 9. The transfer roll 13 had an outer diameter of 40 mm, and was formed by applying a 2.5 mm-thick polyacetal resin on the surface of a cored bar made of SUS304 and pressed against the image carrier 1 with a surface pressure of 12 MPa to be driven. The fixing temperature in the fixing means is 190
° C, linear pressure was 1 kg / cm.

[0039]

[Table 1]

As is clear from Table 1, good development can be achieved by using the low-resistance toner and the low- and medium-resistance magnetic particles (carriers). Further, by improving the transfer means, it was possible to obtain a good image even with the low resistance toner.

In this embodiment, an example in which carbon black is used as the conductive particles to be added to the toner has been described, but other conductive particles such as metal powder of Ni, Al, etc. may be used. The toner may be internally added to the toner, or the internal addition and the external addition may be used together. The toner concentration in the magnetic developer is preferably 10 to 95% by weight. The image carrier is preferably formed in a hollow cylindrical shape, but may be formed in an endlessly movable belt shape and suspended between pulleys made of a conductive material. Further, auxiliary uniform charging means may be provided in the vicinity of the image carrier.

[0042]

Since the present invention has the structure and operation as described above, even when plain paper is used with a simple structure, the image density and resolution are large, and a high-quality image without fog is obtained. The effect is that it can be formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of essential parts showing an example of a developing device used in a developing method of the present invention.

[Explanation of symbols]

 1 image carrier 5 developing roll 12 optical signal irradiation means

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G03G 15/00 115 15/09 Z G03G 9/08 374 9/10 331

Claims (1)

[Claims] 1. An image carrier made of an optical semiconductor material having a light-transmitting property is movably provided, a permanent magnet member having a plurality of magnetic poles provided on the surface thereof is built in, and a non-magnetic material is formed into a hollow cylindrical shape. A sleeve is provided so as to face the surface of the image carrier, and the magnetic developer supplied onto the sleeve is conveyed to a recording area formed between the sleeve and the image carrier by relative rotation of the sleeve and the permanent magnet member. Then, in the developing method in which the toner in the magnetic developer is selectively adhered to the surface of the image carrier by irradiating the recording area with an optical signal corresponding to the original image from the back surface of the image carrier, it is formed to be positively charged. Image carrier and volume resistivity 10 ² ~
A mixture of positively chargeable toner having a particle size of 10 ⁸ Ω · cm and an average particle size of 5 to 20 μm and negatively chargeable magnetic particles having a volume resistivity of 10 ³ to 10 ¹² Ω · cm and an average particle size of 10 to 100 μm are mixed. And a magnetic developer comprising