DE2165031A1 - Electrophotographic process - Google Patents

Description

PATENTANWKLTE

DR. E. WIEGAND DiPL-ING. W. NIEMANN 21650Ί1 DR. M. KÖHLER DIPL-ING. C. GERNHARDT

MÖNCHEN HAMBURG TELEPHONES 55547ί 8000 MONKS 15, TELEGRAMS: KARPATENT · NUSSBAUMSTRASSE 10

December 28, 1971 W 40 895/71 - Ko / DE. '

Fuji Photo EiIm Co. ltd., Ashigara-Kamigun, Kanagav / a / Japan

Electi? Q.photographic process

The invention is concerned with electrophotography using photoconductive toners, and more particularly relates to an improved method of US Pat Electro: phQtographie being one more picture education

VCEusualJif as carried out twice on a single substrate

can. ·

Electrophpt? OgraEh.ische ^ _#> ^ _vr Procedure Using

of photoconductive toners are in Japanese Patent Publication 22645/1963 given; In the process, a very small powder of photoconductivity is

(sprinkled) / evenly dispersed over a conductive substrate / 'and the powder charged at this) time or after the dispersion so that it has the desired polarity, v / ie shown in Pig.1. In the tfig. 1 denotes the BesugsKiffer 1 dap substrate and the BeaugSBiffer 2 denotes the photoconductive toner that is electrically charged with a negative polarity. The distribution of electrical charges within r 20983070 & eO BAD ORIQlMAL

the toner layer is shown schematically as the details are not clear about this. A light image is then focused on the surface of the substrate 1. The electric charge on the toner in the light rays heavily irradiated area is neutralized due to the photoconductivity of the toner and the electrostatic attack •: There is therefore a drawing between the substrate 1 and the toner 2 lost (see Fig. 2, in which the light is indicated by the arrows). Who irradiated with light in this way Toner is then selectively removed from the substrate by suitable means, such as an air jet stream, as follows that the image focused on the substrate is developed (See Fig. 3 wherein the toner 2 is shown selectively removed).

The image obtained according to FIG. 3 can be used for another Material can be transferred or fixed on the substrate. If the toner contains a thermoplastic resin, fixation can be achieved by applying heat or a solvent be effected. If the toner is different colors, try a different color again on the substrate repeating the above Method dispergiM ^ fff ^ if ^ can create an image with two Colors are preserved. In the same way, it is found that a multicolor image is obtained when the above Procedures are repeated as necessary.

Since the photoconductive toners having a relatively simple composition have heretofore been used the toner image remains a considerable amount after fusing of photoconductive constituents, as a result of the presence of the first image the formation of the second image or the subsequent images on the same substrate was obstructed.

In recent years, however, photoconductive toners have been used of superior behavior and these toners have

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those in Japanese Patent Publication, for example 12385/1969, Belgian patent 710 572 and the like specified structure. You can choose from one typically composed of an insulating resin consisting of a clear core, the outer surface of which is covered with a thin layer of photoconductive material is covered. These toners have lower residual potentials after exposure to light and are of uniform construction as compared to the toners; H. which have the same composition within the Toners own far superior.

Obwol

protrude c

an insulating layer without photoconductive properties transferred when the toiler by applying a solvent or fixated by heat 'and their useful structure is thereby destroyed. Especially if that's through such toner formed image as in Pig. 3 and mixed with a solvent 3 as in Pig. 4 shown is sprayed, the toner is dissolved under the action of the solvent and adheres to the surface of the substrate deposited. Palis performing a second electrophotographic Method can be carried out on such a surface of the substrate by dispersing toners .shall occur when the toner is charged - the exposure the same with light to form an image has great difficulty due to the presence of an insulating Layer which consists of the toner that has already been developed, in the case of the newly dispersed toners, in particular in area 21 of the Pig. 4i showing a dissolved toner. The newly dispersed one and therefore charged toner cannot be discharged even when exposed to light rays. On the other hand, the newly dispersed toner in the area 22 easily discharged. That means the second picture

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is seriously affected by the presence of the first image and the reproduction of high accuracy of the second picture becomes practically impossible.

Therefore, an object of the invention is an improved electrophotographic 'method, v / obei the above-mentioned drawbacks of conventional electrical ■ ■ ---} photograph are substantially overcome.

According to the invention, with an electrophq_tß_T "" ~. * graphic process, whereby a practically uniform distributed powdered layer of a very finely divided photoconductive toner, which consists of cores of an insulating thermoplastic resin coated with a photoconductive Layer are equipped, consists of an aj Substrate is formed with a conductive surface and this toner is then electrostatically charged, so that a first image is focused on the toner layer in the areas strongly irradiated by light rays be removed by a suitable method so that a first toner image is obtained, this toner image then fixed. these steps are formed from another on the same substrate Toner layer repeated and a second and optionally

send formation of the photoconductive toner layer on this image a uniform treatment on the substrate at the same time or after the development of the first image is carried out so that the areas with the remaining toner are electrically can be made conductive to the extent desired. The inventor " manure is thus characterized in that a treatment to transfer the to be developed or already developed Toner is performed in the conductive state prior to the subsequent deposition or depositions is to develop the highly insulating character of theon or overcome the already developed toner layer.

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In the drawings are ..

1-3 schematic sections to illustrate the Image forming process using photoconductive toners, which is the basic process of electrophotography represent, . , ■

while the Pig. 4 and 5 are schematic representations showing the stages of the ^. _4th ____. "Show electrophotography according to the invention ... show.

As stated above, the photoconductive toner used according to the invention has a build-up. '_ = construction as stated in Japanese Patent Publication 12385/1969. Such a toner shows practically "no photoconductivity, when the toner is in a layer by means of a solvent or heat fusing of the core of the toner is convicted. The core of the toner, if it is made of glass or quartz, is sprayed onto the substrate a resin solvent is developed or deposited on the toner and in this pail the insulating layer is also formed on the substrate. '■

So that the subsequent image formation stages have no influence of the previously formed image, it is necessary that the previously formed image part a surface resistance value of 10 ohms cm or less and the exposed part of the substrate must also be at a value below the value given above can be set. It is also possible to make only the part of the image conductive, e.g. by means of electrostatic sputtering (Spraying) of conductive particles, with opposite charge than the developed image on which the charge is charged maintained can be achieved.

The nature, principle and applicability of the present invention will emerge from the following description of the invention in detail in connection with the accompanying drawings.

In piss. 1, the reference numeral 1 is a substrate an electrical conductor, such as metal, an insulator with a conductive layer on the surface or a semiconductor bo ~

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draws. In each pall, the substrate or the surface layer of the substrate must have a surface resistance of less than 10 ^ ohms per cm. This can be achieved by a thin layer of an electric charge preventive agent or a conductive resin. Numerous such materials have adhesive properties, but in the context of the present invention, since the photoconductive toner must not adhere to the surface layer of the substrate 1, materials with a low adhesive strength must be selected for this purpose. For this, - that where 5 particles from 10 to 100. U are sprayed onto the surface of the substrate, the surface that has no affinity for the particles is preferred, which means that the particles pass through a weak fabric or impact will fall off, so show no stickiness. This requirement also applies to the following treatment "for obtaining electrical conductivity. Reference numeral 2 denotes photoconductive toners having a structure as disclosed in, for example, Japanese Patent Publication 12385/1969.

• These toners are electric before, at the same time or charged after being dispersed on the surface of the substrate 1. The relationship between the amount of dispersed Toners and their behavioral properties were based on the International Conference for Electronic Photography in Rochester, September 1968, with the appropriate

e toner amount; 50-200 g / cm ² , νο ^ ψί $ & ψοη ^ ΨαΆ ^ η ¥ o1fern with cores made of a transparent plastic resin is found on Applied Optics, Supplement 3, On Electrophotography 1969, pages 124 to 128 and H. Goto, K. Ohbuchi, S. Satainatsu, H. Kato The Image Forming Process of Photoconductive Toner referenced.

The tray of exposure and development will be the one in Pig. Condition shown received. The development can be done by an air blower or by rotating glass beads with proportionately large diameter can be achieved on the surface of the substrate. The fixation stage shown in FIG can be removed by spraying a solvent over the remaining Toner or by applying heat to the remaining

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toner can be achieved. Palls the core material of the .. .kS! ^ M «LiS§S ^e fiSffiSlB ^ girf ^e iSffeSlS ⁿ n58SSÄig is-

can be dissolved in a solvent / the fixing stage can be carried out by spraying on a solution of a binding synthetic resin »such as silicone resin _v .. polyvinyl acetate,

/ Chloride, vinyl acetate, polyacrylate, polymethacrylate polymer "and the like can then be achieved.

The electrical conductivity treatment that is the characteristic feature of the present Invention represents, can at the same time, with this pixel

\ y before the second spray process / stage or as an independent "stage / äused. Im the former case becomes a solvent or a solution containing an electroconductive resin or a charge preventive agent contains, in the fixing process to achieve the fixation and to achieve the electrical at the same time Conductivity used. . . Since numerous resins that make up a surface make conductive, and numerous charge prevention agents

- in polar solvents such as water, methanol and ethanol are soluble, and, in view of the fact that the core material of the toner, namely vinyl chloride, vinyl acetate, Polystyrene, polyacrylate copolymers are soluble in non-polar solvents, unfavorably in habitual form are contained, the charge preventive agent or charge preventive resin may be made into a separate one Solution can be processed and sprayed onto the already fixed image.

If the fixation and the guiding at the same time which is the case when a liquid that dissolves the photoconductive toner and the conductive resin contains may be a resin or an agent

° advertising o 'the or conversely the Fixierharzlösung may be in the form of a Q colloid are dispersed in the conductive agent, dispersed to Leitendmachung that is not essential "■ lent is achieved in the fixing solution in the form of a colloid. **> As a means of achieving conductivity, ο quaternary ammonium alc polymers (polyvinyl-eenzyltrimethylammonium chloride and the like), polyvinylbenzenesulfoxide \ colloidal alumina, colloidal silica and similar materials can be used. Furthermore, quaternary

Ammonium salt type cation activating agents or the like be applied for the same purpose. In addition, those described in U.S. Patents 3,295,967 and 3,288,770 or Japanese Patent Publication 14035/1969 can also be used. Since the polymer or the interface activating agent exhibits adhesive-type tendencies, colloidal alumina can be used or colloidal silica material may be dispersed therein to reduce adhesion.

It follows that, according to the invention, the selection of any particular conductive agent or charge prevention agents critical. is. The material can come from a large group can be selected, the above-mentioned materials being only examples, as long as those mentioned above Conditions excluding conductivity and stickiness to be fulfilled. It can be seen that the ideal material does not adhere to the material applied later Toner is, and therefore, as the adhesiveness increases, the excellent results of the invention worsen.

"It is important that in achieving conductivity The treatment carried out does not damage the quality of the image that has already been formed. the The above-mentioned means for achieving conductivity form a transparent layer over and out of the image Basically, they can be used to achieve multicolored images be turned. An amount of 1 g to 10 g per 1 m of the product to achieve conductivity. applied to the picture surface and this amount becomes even then not significantly changed if the agent contains other high resistance components. The important feature lies ο that the surface resistance of the image area is less

S is 10 ⁹ ohms per cm ² . bypassing the

Q The substrate treated in this way leaves; the \ an-. > · Closing stages regardless of the presence or absence of

O- -

cd Presence of the toner image on the substrate. In Fig. 5 eats

ο the case shown where the electrically conductive layer 3 is over ■ the ^ toner image is formed.

. The · .... ElektropJhotog ^ phie according to the invention further explained in detail with reference to the following examples, without being limited thereto.

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Example 1

A mixture of the following substances was in a K mill ground and mixed; . ■. .; · -: ■ ·. · ■. ".

photoconductive zinc oxide (ZnO, ^ .-. · ". ·;«. · ■: -.-.- Sasex. # 2000, product of Sakai Chemical Ind .; 15 parts by weight

Silicone resin paint I ¹ SR-107
. (Product of the Fuji High Molecule Ind. Go.)

(Methylphenylsiloxane) x 50 parts by weight

Cyclohexane. -. 100 parts by weight

. .20 parts of the ground, and. dis-oerated mixture became 70 parts of polymethyl methacrylate resin granules with an average grain size of 70 microns with an absorption factor for radiation of 3800 S of 2.5-mm, v / as is within the specific sensitive wavelength range of zinc oxide, added and stirred and a coated photoconductive powder in the dried Condition preserved.

The photoconductive toner thereby obtained became on

a conductive black paper (soot-containing paper) with a UDerriac conductivity of about ^ Q-2 / area

(10 ¹ ^ ⁰ square) at 50% HH W

an amount of 80 g / m 2 surface area and the black paper carrying the toner particles ·. · ■ electrically in a dark room by corona discharge to a negative \ whereby the initial arrangement of the powder layer was about 300 V J polarity ~ resolved "düiiv.'liachdem" the black paper has been exposed to license, a stream of air was blown on the paper so that a white image was obtained on a background of black color.

About the image formed on the black / white paper became a fixation and conductivity achieving liquid from 10 parts of ECR-34 (Dpw Chemical Co., aqueous LtJ-

Weight
solution with a content of 35/9 »polyvinylbenzyltrimethylammonium chloride), 30 parts of Alumina Sol 100 (product of Nissan Kagaku * Co., aqueous colloid system with a content of about 20% colloidal aluminum oxide), 20 parts of acetone, 50 parts of dimethylformamide and 90 parts of methanol sprayed onto the element so that an amount of 2 g / m 2 of the non-volatile layer remained on the image.

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- ίο -

After the first image was thereby completely fixed, a second image was formed over the first image and a photoconductive toner prepared in the following manner was used; - ........

Cadmium- £ elb ~ prans.e (product of. 150 parts of HitsuBisni Hetal Mining Co.)
• FSK-10 silicone resin coating? of Puji High Molecule Ind. Co. 40 parts

Cyclohexane 120 parts

The above substances were ground and kneaded in a ball mill for about 17 hours. 30 g of the ground substances became 100 g of one granular powder was added, which was sieved an acrylic material MH-105 from Fujikura Kasei Co. lait

—1 an absorption factor of 1.8 ram for radiation a wavelength of 5500 S. within the specific sensitive wavelength range of cadmium-yellow-orange on a minimum grain diameter of 35 microns and one maximum grain diameter of 104 microns was made, was added. The mixture was continued to stir and stir Using hot air, dried and lightly ground in a mortar to a powdery structure.

The resulting powder was over the first image

iiL an amount of 0.008 g / cm dispersed, jolßk, trisch Gew with the eleEtriscne from initial voltage about 260 ν was ^ö

load, exposed to light to form a second image using a xenon larape, using developed on the surface of blown compressed air and the second image in yellow-orange without any influence through * r first picture? obtain. The second picture was fixed using dimethylformamide, thereby obtaining a two-color image.

For comparison purposes, the first image was simply fixed by dimethylformamide, dried and then that second image formed in the above-mentioned manner.

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The yellow-orange toner stuck over the first Image and a faithful reproduction was not obtained.

Example 2 . '. ^

Each in the same procedure as in Example 1, the first photoconductive toner was prepared and used in the following manner. An art paper - that is, a high quality clay-coated paper with a surface conductivity of about 10 ^^ / area (mho square) at 70% RH
used as substrate:

";.. Acrylbase MH-105 (granular polyraeth-

acrylic acid-ethy! polymeres of the Fu; jikura ; "· ■ Kasei Co. with a K ~ ¥ ert of 60-70 and a grain size of 60-100 mesh) .50 parts

Fuchsin. 0.1 parts

'Methylene Chloride' 450 parts

Vln a calibration fö gl-shaped Lös ung transferred / After aas above mixture was wörtren / was

it is dried to a powder-like structure with an absorption ^{factor of 0.9 x 10 mm -1 for} irradiations with 3800 % within the specific sensitive wavelength range of zinc oxide by means of a spray dryer using an air spray. To 50 parts of this powdery substance, 20 parts of the following mixture were added, stirred and dried using hot air.

photoconductive zinc oxide (ZnO: Sazex 150 parts. ·. 3F £ 00p. Product of Sakai Chemical Ind.), _

Polystyrene. 15 parts.

. Cyclohcxane _Λ 250 parts

The resulting core bodies .'wurden red when they were fixed by means of a solvent. To the Fixation was a mixed liquid content of 1: 1 from dimethylformamide and methylene chloride applied. For treatment to achieve conductivity was a liquid made by mixing 100 parts of a

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10 $ aqueous solution of fSO ethylbenzene potassium sulfonate, 40 parts of colloidal silica as a dispersion in water with a content of 20 $> silica and a trace of dodecylbenzene sodium sulfonate was used. This was sprayed over the first image in an amount that resulted in 3 g / m 2 of the non-volatile layer after drying had been carried out.

The second image was formed in the same manner as in Example 1. Equivalent results were obtained. ■ '

Example 5

Following the procedure of Example 1, the Fixation and conductivity treatment carried out simultaneously with the following liquid:

, _.Polyvinvlbenzp.lkaliuinsulfQnat (the Vis- 1C parts

kositajb from 1u & ew.% of Verbinaunp; in 1% aqueous NaCl solution was 50 cp)

Polybutyl methacrylate water emulsion (non-volatile substance 20 ^) -. .50 parts

Water 140 parts

. This treatment liquid was not of the toner image of water-repellent character due to the Presence of the anionic activator in the emulsion rejected. Excellent results have been obtained.

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Claims (3)

Claim (iy electron photographic.es method, v / obei a uniform powdery layer of photoconductive toner particles with a core body made of a transparent insulating substance and a photoconductive one formed on the surface of the core body Layer is formed on a substrate with a suitable electrical conductivity, this powdery Layer electrically charged, exposed to a first light image, which in the one with light is strong irradiate the area lying toner particles are removed from the surface of the substrate and the remaining Toner particles are fixed to form a first image, with at least one additional Layer of photoconductive toner particles uniformly on the same substrate is formed and the. above steps to obtain an image on the same substrate repeatedly v / ground, characterized in that after the formation of an image, but before the formation of a subsequent photoconductive toner layer, at least the toner layer by using a material that has essentially no adhesiveness to the Shows toner, is made electrically conductive, with at least the first toner image a surface resistance 1o 2 was given by less than 10 ohms / cm, under Use of a solvent or heat so that the region of the previous picture is an Aelectric '_.
suitable / has conductivity. 2. The method according to claim 1, characterized in that the treatment for issuing the guidance 209830/0990 JAMtOiKO GAS 2165Ö31 ability and fixation in a single stage (simultaneously) executes. 3. The method according to claim 1, characterized in that that colloidal aluminum oxide is used as a means of treatment for imparting conductivity. 209830/0990