DE1205829B - Process and liquid developer for making electrophotographic images - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

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GERMAN PATENT OFFICE

EDITORIAL

Int. α .:

G 03X4

German class: j57-b-18

Number: 1205 829

File number: C 25215IX a / 57 b

Filing date: October 6, 1961

Opening day: November 25, 1965

The invention relates to a method and a liquid developer for producing electrophotographic Images in which on a photoconductive layer, which consists of a photoconductor and a binder consists, an electrostatic charge image is applied, which is then mixed with a liquid Developer is developed, which consists of a carrier liquid and a toner.

It is known to develop charge images by dusting with a toner of the appropriate polarity and subsequently to fix the toner image by fusing, the toner image prior to fixing to a Image receiving material can be transferred.

Furthermore, the development with a liquid developer is known, in which the melting of the toner image not applicable. The well-known liquid developer is able to fix the image by itself, because a Fixing agent in the developer binds the toner particles to the recording material through an adhesive effect, after the carrier liquid has evaporated. The carrier liquid is for this purpose for the Fixer a solvent.

The disadvantage of this process of liquid development is the reduction in electrical resistance the carrier liquid through the fixative. In particular, the electrical resistance of the liquid developer decreased during storage, so that the shelf life of the developer is quite limited.

The object of the invention is to specify a method by means of which good adhesion of the toner image on the image carrier, as it can be achieved during fusing, is also achieved for liquid development. Furthermore, the developer should have a simpler structure, a larger electrical resistance and a have better shelf life.

The invention relates to a method for producing electrophotographic images, in which in the photoconductive layer as a binder and an incompletely cured material in the developer Carrier liquid a solvent is used for the binder.

The invention also relates to a method for producing an electrophotographic recording material to carry out the method described above, assumed in which is that a photoconductor is dispersed in a binder and a solid layer is produced from the dispersion will; this method is characterized in that it uses a curable binder becomes 5 <> after dispersing the photoconductor 40 to 60%, based on the hardened state, is hardened.

Process and liquid developer for
Production of electrophotographic images

Applicant:

Commonwealth of Australia,

Melbourne (Australia)

Representative:

Dipl.-Ing. E. Rathmann

and Dipl.-Ing. R. Mertens, patent attorneys,

Frankfurt / M., Neue Mainzer Str. 40-42

Named as inventor:

Kenneth Archibald Metcalfe, Fulham;

Robert John Wright, Hectorville (Australia)

Claimed priority:

Australia 7 October 1960 (65 385)

The incomplete curing allows the photoconductive layer to soften during immersion into the liquid developer. This leads to a binding of the toner particles to the recording material, without the need for a fixative in the developer. However, the hardening should be sufficiently complete, to ensure that the softening occurs only on the surface of the recording material without that the latter is too much weakened in stability.

Another object of the invention is a liquid developer, which is characterized in that that the carrier liquid from a solvent for the partially hardened binder of a photoconductive Layer consists.

The carrier liquid consists of a hydrocarbon, preferably cyclohexane or trichloromonofluoromethane.

The objects of the invention ensure that the carrier liquid of the developer is not specific a fixing agent needs to be added, which reduces its electrical resistance, because the carrier liquid acting as a solvent for the binder of the photoconductive layer is capable to soften its surface, so that the toner particles in the softened photoconductive Can store shift. After the carrier liquid has evaporated, the toner then adheres firmly to the recording material.

509 739B78

The invention is described below using an exemplary embodiment with reference to the drawings explained. It shows:

F i g. 1 shows a schematic cross section through a recording material,

F i g. Figure 2 is a similar cross-section, but shows how the developer is applied to such a material acts and

F i g. 3 shows a similar cross-section through the finished picture.

The recording material consists of a substrate 1 made of paper or the like Material on which a conductive layer 2 is applied and on which in turn a photoconductive layer 3 which consists of an at least 40% hardened binder 4 and a photoconductor 5. Of the Photoconductor 5 is dispersed in the binder 4.

The liquid developer 6 consists of a carrier liquid 7 which has an electrical volume resistance of at least 10 ¹⁰ ohm · cm and a dielectric constant of at least 3, so that the carrier liquid does not destroy the charge image on the photoconductive layer during development. The toner particles 8 are dispersed in this carrier liquid.

The carrier liquid 7 is able to dissolve the photoconductive layer 3 on the surface 9, provided that Binder 4 has not been fully cured.

The conductive layer 2 can be, for example, an aluminum layer that is applied in a vacuum Layer carrier 1 applied, for. B. has been sprayed on.

The following are examples of the composition of the recording material and the developer given:

example 1

The photoconductive layer had the following composition:

Alkyd resin modified with phenolic resin and linseed oil with a proportion of
solids from 59 to 61 percent by weight, an acid number from 8 to 12,
a specific gravity of 0.96
where for modification to 100 kg
Alkyd resin 2801 linseed oil is used

became 100 g

Zinc oxide 180 g

Dryer, 4% ig s ^e cobalt naphthenate 0.5 g
Dryer, 15% ig ^e s .. 1.0 g of lead naphthenate
Toluene 200 g

These ingredients were mixed on a ball mill for 8 hours or on a single roller mill for 1 hour long ground together. The resulting coating liquid was on a paper sheet or on a metal sheet using conventional coating methods, ζ. B. by immersion, spray or electrostatic method or applied by means of a doctor blade. After that, the shift lasted for 1 hour kept at 60 ° C, i.e. hardened.

Next, the photoconductive layer was charged by corona discharge in relative darkness.

The charged recording material was imagewise exposed to light or X-rays, e.g. B. by contact or projection exposure, or by exposure in a conventional camera.

After the generation of the charge image, the following composition was used with a liquid developer developed:

Toner (polyvinyl chloride coated carbon particles) Ig

Hydrocarbon fraction from 60 to
145 ⁰ C, a specific gravity
of 0.74 and a proportion of aromatic substances of 10 percent by weight 500 cm ³

The toner was dispersed in the carrier liquid with a pestle and mortar. The dispersion was used as a developer, the toner being attracted to the negatively charged image parts. At the Evaporation of the carrier liquid fixed the toner to the photoconductive layer.

Example 2

The photoconductive layer had the following composition:

Silicone resin 480 g

Zinc oxide 1200 g

Toluene 500 cm ³

These ingredients were milled into a dispersion in a ball mill for 8 hours or in a single roller mill for 1 hour. The resulting paste was mixed with a further 500 cm ^{3 of} toluene and applied to a layer support. Curing was achieved by heating at 90 ° C for 1 hour.

The photoconductive layer was then charged as in Example 1 and exposed. After that, that became electrostatic charge image developed in a developer of the following composition:

Soot or printer's ink Ig

Cyclohexane 500 cm ³

After the carrier liquid had evaporated, the toner was anchored in the photoconductive layer.

One photoconductive layer of the above composition was cured at 93 ° C. for 1 hour, a second at 205 ° C. for the same time. Only in the photoconductive layer cured at 93 ° C. was the toner anchored in the photoconductive layer after the carrier liquid had evaporated.
50

Example 3

The photoconductive layer had the following composition:

Polystyrene / 500 g

Zinc oxide 1200 g

Toluene 500 cm ³

Monomeric styrene 500 cm ³

These ingredients were baked on a ball mill for 8 hours or on a one or three roll mill for 1 hour mixed. The coating liquid thus obtained was coated in a conventional manner Paper web or a metal sheet applied. After drying for 1 hour at 71 ° C, the photoconductive Layer charged and exposed in the manner described above.

Claims (1)

The development of the charge image was applied by means of a layer of a photoconductor and a binding agent, a liquid developer, and the latter was achieved: with a liquid developer made from a carrier toner (red, organic pigment liquid and a toner Particle1) Is 5 characterized by the fact that the binding cyclohexane ''. '.'. '.'. '.'. '.'. '.'. '.'. '.'. '.'. '.'. '.'. '. 500 cm «center; "A volktadig kind of material and i as a carrier liquid em solvent for the trichloromonofluoromethane (CCl3F) .. 500 cm" binder is used the one process for the production of an electrophoto hydrocarbon fraction of 54 to 10 graphic recording material to the 700C, a specific gravity below the Process according to claim 1, in which from 0.67 and a proportion of aro-. eu \ photoconductor in a binder dispersed matic substances of 1 weight urid a solid layer is produced on the dispersion rj% 500 cm3, characterized in that a hardenable P 15 binder is used and after the dispersing of the carrier liquid after evaporation of the persisted Photoconductor up to 40% of the binder until toner adhere to the photoconductive layer. 60%> based on the hardened state,. . is hardened. ti e ι s ρ ι e 1 4 3_ Method according to claim 2, characterized in that the photoconductive layer had the following composition: the photoconductor-binder dispersion is applied to a layer support. Linseed oil-modified alkyd resin with a 4 method according to claim 2, characterized in that the content of solid substances from 59 to is characterized by the fact that em binding compound consists of a hardenable 61 percent by weight, an acid number plastic, in particular a silicone resin, from 15 to 25, a specific gel 2S ei? em polystyrene or an alkyd resin used weight of 1.01, whereby for the modification, 100 kg of alkyd resin 4001 linseed 5 · FluAsif r> electrophotographic developer oil were used 100 g with implementation of the method according to claim 1 zinc oxide 180 ε from emer carrier liquid and a toner, toluene 200 ε 3 °, characterized in that the carrier liquid consists of a solvent for the partially The photoconductive layer was hardened for 16 hours binder of a photoconductive layer at 60 ° C. and then hardened as in Example 1 - consists. ■ used to position an image. 6. Liquid, electrophotographic developer 35 according to claim 5, characterized in that the claims: carrier liquid composed of a hydrocarbon, 1. Process for the production of electrophotogra- preferably from cyclohexane or trichloromono- Fischer pictures, which insists on a photoconductive fluoromethane. 1 sheet of drawings 509 739/378 11.65 © Bundesdruckerei Berlin