DE1497221A1 - Process for the transfer of electrical charges by means of liquid layers - Google Patents

Description

D1PL.-ING. F.Weickmann, Dr. Ing.A.Weickmann, Dipl.-iNG.ii. w D.IPL.-PHYS. Dr. K. FiNCKE patent attorneys. ' S MUNICH 17, MDHLSTILASSE 21, KUFNUUHEIT 413921/22 'I 7 9/2 2

RANK ΧΒΒΟΣ LIMITED

37/41 Mortimer Street, London, W.I / Engtand

. ι. . . . .ι Ii ₍ - -; M ~ m - mm * m-.

Yerfahrea to the contract. of electrical charges

£ by means of liquid soils

The present invention / relates to application of electrical charges by means of liquids for electrical | Static HD Formation Devices ^ .. In particular, see ^ the invention to a chemical; Doping such liquids, whereby the transmission characteristics for electrical charges are controlled to create a charge pattern: transfer between opposing surfaces, yon obtain various imaging materials; the charge transferring Liquid separates, while the opposite-Λ lying surfaces. J

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The transfer of electrostatic charge patterns has found a variety of uses in the field of Xerography and related electrostatic printing processes have proven advantageous. In the case of a common xerography procedure, as described, for example, in US Pat. No. 2,297,691, a xerographic Plate, which consists of a layer of photoconductive insulating material applied to a conductive support, A uniform electrical charge is applied to its surface, which is usually achieved by means of conventional Projection techniques through the "bu reproducing object is exposed. During this process, the plate discharge depending on the radiation hitting them, creating a latent electrostatic image on or in the photoconductive layer is created. By applying 'finely crushed ^ electrically charged material, such as

wise electroscopic powder, on the photoconductive layer the latent image is developed with the powder being electrostatic is held on the contact surface in a pattern corresponding to the latent image. After that, that is developed xerpgrafisehe powder image usually on a 'carrier'. transferred surface on which it. is attached by suitable means «by charge transfer from the xerographic plate on a suitable dielectric surface it becomes possible electrostatic image. to remove the dielectric surface

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wrap. It / thus becomes possible / the destruction of the photo

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conductive layer or the need to clean it, whereby the service life is increased.

In U.S. patent application Bor. 193 277 a new image generation process has been proposed which is called "thermoplastic recording" and with which a liattertoi ^ epr ^ duktioa. {Oontinous * tone. Reproduction) is possible. Dabtt is transferred to a charged thermoplastic resin a Jötöleiter _t is an image projected * wherein check the plate according dee image yerformt if ei # duroh drying is developed "the drying is IfÄriiiezufuhr or a solvent Trorgenomnien ,, whereby the thermoplastic layer is given a microscopic uneven Öberflaohe. piping uneven surface can can be described as wavy, striped, wrinkled, curled or "dull soled". Me * Lpcal deformations are so milky, whereby the 5) formations depend on the strength of the light irradiated into the various areas. It arise. abweohseatnd equally spaced elevations and valleys of variable width and / or height Boundaries arise * Such fields also cause a deformation of a thermoplastic layer and only form relief-like elevations at the mentioned boundaries. Sqlohe patterns

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can be used directly or _{eliminated or reduced in size by long enough trookneai (} jflee deformable material until a frost pattern is created). The image produced in this way can be used in various ways for optical projections or lessons a "solvent with simultaneous uniform light irradiation" can be deleted, but the intensity and the irradiation time is higher than during development

Various methods are known for charging a thermoplastic layer in order to achieve deformation of the layer. The use of a charge transfer layer between the thermoplastic layer and the photoconductor is suggested in the aforementioned patent Ser. No. 193,273 The technology of! charge transfer has many advantages. There is the option of opaque or colored To use photoconductors in imaging systems, where the final image is checked by projection without the ability to project high-efficiency white light images is limited. Another benefit is there therein ,, that charge transfer processes involve the use of Make photoconductors possible, which in other processes because of 'the high spontaneous arrogance discharge are uncommon ", Finally, the method is advantageous because the conductive substrate is made of a suitable charge-absorbing dielectric such as a thermoplastic layer used for this purpose

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can be to impress a field on the photoconductor during the exposure; This makes corona discharges unnecessary, with which the photoconductor is charged in known methods. Therefore, only low voltages are required with respect to corona discharges. The use of a narrow air gap as a charge-transferring medium between two surfaces is known from US Pat. No. 2,973,943 / Although charge transfer via air or other gaseous media is a common method, it has some disadvantages. Initially, the charge transfer does not occur until a critical threshold voltage of a few hundred volts is exceeded. There are no serious disadvantages associated with the presence of such voltages if the amount of charge to be transferred is relatively large and the exact value of the amount of charge transferred is not critical. In imaging systems with high demands on image quality, such as continuous tone reproduction, it is, however, extremely difficult to precisely match fine gradations of the transferred charge, which ultimately represent the fine gradations of image density. This disadvantage adheres to the. Charge transfer via gas breakthroughs generally occurs because it is imprecise because the required voltage depends on the width of the gap. There are uniform gap widths required by about 10 / u to a l aduhgs * - transfer possible to make _e gap widths of this magnitude, however, are due ttagenauigkeiten the Materialoberfläohen difficult to achieve '' from US Patent 2,975,052 is

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known that a thin layer of liquid acts as a charge transferring Medium can serve and that such layers provide a higher accuracy than air or gaseous media. It has shown that the transmission properties of Liquids must be adapted to the specific application. Therefore, there must be a coupling between two layers forming charge-transferring liquid be designed for each application so that a sufficient amount of charge arises «For the use as a charge image transmitter on a defarmable plastic layer stand for. the electric Control defined critical limits. It has shown, that for the method according to the invention too little electrical Resistance means a loss of image accuracy. On the other hand, too high a resistance can lead to - no Image or just a very faint image on the thermoplastic Sohioht arises. Therefore, the liquid used must be considered in terms of their electrical properties within more precise

i
There are limits to transferring a sufficient amount of charge to achieve the image deformation described above. For obvious reasons, it must also be chemically compatible with the materials of the adjacent layers.

It is known that certain commercially available materials as described, for example, in U.S. Pat. No. 2,975,052 Silicone oils lead to the desired results. Anyway, it is generally not possible to get one in the trade

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borrowed. MateriaHäaäie of desired physical properties to find which are in the optimal resistance range * In addition, it is not known that such materials are suitable for the special purpose of charge transfer. ν Therefore, no value was placed on / to manufacture the materials • in such a way that their electrical properties always lie exactly in the area which they are for a special Makes charge transfer suitable. The resistance area must be observed very precisely for a charge transfer | however, impurities that are almost always present and vary from batch to batch change with unknown additions the resistance range in such a way, that these liquids, are unsuitable for charge transfer purposes.

Investigations on which the invention is based have shown that liquids suitable for charge transfer are produced can be made by adding a liquid of raw resistance is doped, making the resistance controllable, reliable and reproducible · in an optimal range is reduced,

It is therefore the object of the invention to create liquids with suitable reproducible conductivity characteristics for charge-transferring arrangements which have a higher dielectric strength by introducing doping materials into liquids; the liquids should t ■. . be able to charge charges from metallic layers

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to transfer dielectric layers and- as an intermediate layer between a photoconductive and a charge-absorbing layer Layer, in particular an imagewise deformable thermoplastic Layer, be suitable.

In a process for the transfer of electrical charges on a surface of an electrically insulating charge-receiving Layer is therefore provided according to the invention that applied between the on a conductive substrate

one

electrically insulating charge-receiving layer and / charged carrier layer, which exists between the conductive substrate and the charged carrier layer for a predetermined time an electrical Beb compound, a

coupling layer is used, which consists of a, a to reduce their resistance to one for charge transfer liquid of high electrical resistance containing suitable value doping material consists*

Further details of the invention emerge from the The following description of exemplary embodiments based on the figures. It shows:

Fig. T is a schematic representation of an arrangement for Transfer of charges from a metallic containing an image in the form of a relief-like pattern Layer on an electrical charge receiving layer j

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Fig. 2 is a schematic representation of an arrangement for ' Transfer of charges from a dielectric substrate containing an electrostatic image on a dielectric charge receiving layer j

Fig. 3 is a schematic representation of an arrangement for Transfer of charges from a photoconductor to a thermoplastic deform in the form of an image * bare sohiohtf and "

Fig. 4 shows a family of curves ,, the cooperation between the Hague, shows with different charge transfer to be achieved ElÜeaigkeiten resolving power and the time period between the charge transfer and the development of the electrostatic image _v.

1 shows an arrangement for applying a charge image on a dielektriscu, o layer, being charge-bearing Liquids according to the invention used wercU η. The various elements are designed in the form of a multi-layer arrangement. This contains a charge-absorbing Layer, which in turn consists of a carrier 10 on a possibly * conductive layer Tl (required if the carrier 10 has a dielectric character) and a dielectric Sohioht consists. This charge-receiving layer is electrically conductive through an intermediate layer 13 of a charge-transferring liquid on a conductive or semiconducting one

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Sohicht 14 stored, which he must have a pre-formed picture relief 15 contains. In the illustrated embodiment, the Arrangement made so that the charge-transferring liquid, only that covers the protruding parts of the relief. It has been shown, however, that suitable liquids with limited conductivity charge selectively from the protrude beyond protruding parts, even if the spaces are completely filled with liquid. About a Switch 18 is a voltage source 19 to substrate 14 and the conductive layer 11 switched.

Metals such as aluminum have proven suitable for the substrate 14 provided with protruding image parts 15. The charge-absorbing body consists of the 7 _} 62x10 cm thick carrier 10 made of Mylar, which is coated with the thin layer 1.1 made of aluminum and the 5.08x10 cm thick layer 12 made of Velsiijol X-37 (from Velsicol Chemical Corp ”) isb. The Velsicol X-37 is a 125 milliliter diethyl ether

dissolved monounsaturated primary complex

(60 grams). ) he space between the Seliefbild and the load-receiving body is filled with a charge-transferring liquid, which consists of approximately 0.5 fo in liquid Jüb-orkohlenstoff dissolved trifluoroacetate "The fluorocarbon is from Minnesota Mining and Manuf ac touring Comp Delivered under the designation FC-75, It consists of the. essentially from cyclipchem perfluoroethers from empiris

hen formula Cg]? .. gO. With the relief-shaped, at

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The negative TqI of the voltage sexual 19 connected ¹ rail 14 will carry charges corresponding to the protruding areas on the surface of the layer 12. The substrate 15 'is then removed - the layer afflicted with the charges, can be treated further using techniques known per se. "It has been shown that voltages of the order of 100% are sufficient for this charge transfer, which can be achieved with conventional xerographic processes such as Cascade development can be treated further. If the charge-transferring liquid is not used, so bil-. there are no noticeable charges on the charge-absorbing layer at 100 yoIt. It is only at voltages of 200 volts and above that a weak image can be determined as a result of air breakthrough effects. When using special charge-transferring liquids, the improved uniformity of the electrostatic image obtained is evident. "■■ -._ * .. ·

When positive 'charges on the same charge-absorbing Layer are to be transferred, delivers the described 1 * 0-35 liquid, for contact times of 1 second and less, extremely faint images, for! the transfer of positive charges a preferred liquid consists of about 0.2. # Trifluoroacetic acid dissolved in hexamethyldisiloxane; hexamethyldisiloxane is a silicone fluid with a viscosity of 0 ^ 65 oentistokes from the company

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Dow Chemical Company or General Electric Company. The liquid accordingly delivers positive charge images on the charge-absorbing layer. Both related to The liquid described in the embodiment according to Jig, 1 consist of a liquid base material of high resistance, which is used to produce the desired conductivity range can be doped for charge carriers of a certain polarity. Furthermore, the liquids are evaporable, so that the electrostatic images created by.! charge transfer immediately after the charge transfer through dry powders or other means can be developed without there being the liquid Layer bothers.

A visible Heliefmusters a uniform charge transfer from a planar conductive surface may be other than the charge transfer over the protruding portions of the described arrangement to take place in order to sensitize for example, a xerographic photoconductor ₀

In Fig. 2 is a further embodiment, -in the charges are transferred from one dielectric layer to another ο In this case, a carrier 25 becomes a conductive one Layer 26 'and a dielectric layer 27 of existing, charge-absorbing body by a roller 2o ^ e against a charged, layer coated with a charge transferring liquid film 30 and deposited on a conductive substrate 31 29 pressed. The charged dielectric layer 29 ″: ax; n

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for example from an S ¹ Ot ο it er, on which a charge grid is generated by uniform charging and by irradiation with an optical image. The charge-transferring liquid can be applied both before and after the charging of the sheet 29. The charge-absorbing dielectric layer 27 can consist of a deformable material in order to develop deformations. Likewise, a non-deformable material can be used for powder development or some other form of electrostatic image use.

3s has proven to be beneficial that the liquid layer 30 is divided by the fact that too much liquid is now applied to the top layer 29 and that after the formation of the electrostatic image, the layer 27 that absorbs the liquid is then replaced by a Ueite is rolled up, whereby the excess liquid is squeezed out and a uniform film is formed. Instead of a should, for example, a Teflon sheet, about as wide as the charge-absorbing layer, can be used. Such a production of the liquid. ücliicrrb prevents the formation of cavities and bubbles. The thickness of the liquid layer is essentially determined by the pressure and the number of overflows. pressure-transmitting devices and determined by the flexibility of the carrier layer 25. Does the tracer layer 2.5 consist of 7? 6x10 cm thick Mylar, so fühifc a medium hand pressure with a Teflüxi- ^ lc "vb" i..sci "ileifer üu a middle layer of liquid- -j γόη utv / a 1 to 2 / cu with -repeated stroking over

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or thinner substrate thicknesses, film thicknesses of less than 1 / U can be achieved. On the other hand, with reduced pressure Film thicknesses of about 5 / rev can be achieved. As the charge transfer not critical with regard to the liquid film thickness there is no need to make great demands on them in terms of accuracy.

If the conductive substrates 25 and 31 are electrically connected by the switch, the charges are distributed on the layer 29 in such a way that, after the separation, the potentials of the layers 27 and 29 are approximately equal. The type of charge-transferring liquid layer 30 in the arrangement according to FIG. 2 depends on the required conductivity and other physical properties. If liquid is to be capable of evaporation, the same liquids as those described in connection with the exemplary embodiment according to FIG. 1 can be used. In addition, the FG-76 liquid fluorocarbon manufactured by Minnesota Mining and Manufacturing Company is vaporizable. Trifluoroacetic acid is also suitable as a doping material for this liquid. About 0,001 ° / o trifluoroacetic acid in FC-75 are sufficient to achieve the required conductivity for the transfer of negative charges. Slightly larger quantities are required for the transfer of positive charges. Other suitable dopants for these liquids are trifluoroethanol, m-aminobenzene trifluorite and iviethyl trifluoroacetate.

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In jig. Figure 3 is an arrangement for applying an image charge shown on a deformable image carrier layer, in which ' ! Liquids according to the invention. Find use »How with the arrangements according to Jig. 1 and 2 are the individual .. elements ea in an electrically coupled multi-layer arrangement joined together, which is a thermoplastic layer 40 and layers applied to it in the form of a conductive layer 41 and a flexible substrate 42. Located on the opposite side of the thermoplastic layer one separated from this by a layer of liquid 43 and photoconductive layer 44 deposited on a conductive substrate 45

The arrangement shown offers many gate parts: no separate charging step is necessary, and it does photoconductors with relatively high "dark currents" can be used; IOt ο le it er can be used which have a kap'aaitive Require coupling on their free surfaces; high yields of uants can be achieved by taking up unfortunately relatively large upright on the image receiving layer get,! will; /

There can be a larger amount of charge !! accumulate than can be saved by “■ he image on naiirae layer; . · UiK'-. it köniioi- ^ leiclifürmige charges for Empfindlichkeitsmeij-sv / corner si - be discharged oüer. _. .

- jjie thin vt-s.i.Or.uierb & re layer 40 consists of a material

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which is usually hard and electrically insulating, however can be temporarily softened by the application of heat or a solvent. Layer 40 can be opaque if only reflection is taken into account} it can also be transparent - and is usually also as in the present exemplary embodiment. Layer 40 is shown here evenly thick; sje consists of an approximately 2 to 5 / U thick thermoplastic resin with a flat surface, the material selection is not for a relief-like figure as critical as for a matte picture; It is a big It is possible to choose from materials with electrically insulating properties, which can be dried in stacks. The table indicates materials, which are suitable for a re- and / or matt imaging by deformation.

Handicapped -
Piccotex

Piccolyte
Staybelite 5
Btaybelite 10
Piccoumaron

Chemical name

lerpen resin resin ester resin ester Oumaron

Piccolastic D15Ö styrene

Piecoflex 100A polyvinyl chloride

Neville ^ R13 '- Coumarone Inks

Uevillac soft Phena is ready for you

Manufacturer

Pennsylvania Industrial Chemicals Co.

Hercules Powder Co,

Pennsylvania Industrial Chemicals Co.

"■

Heville Chemical Co.

Il

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Trade name Ghemisolie Designation manufacturer

Nevillac soft coumarone in Piccolastic E125 styrene

leville Chemical Go.

Pennsylvania Industrial Chemicals Co.

Picco 75
Piccopale 70

In the

Hydrocarbon
(unsaturated)

Piccolastic A-50 "Styrene"

Piccolastic A-75 styrene "" .. ".-

The layer 41, which is approximately 1UO "to 800 Anstrom thick, is conductive and consists of a material such as copper godide, Aluminum, chromium or inc one 1; ! Layer 42 consists of o a material of sufficient strength to support the layers applied to it; the material used is Mylar, üodar-l-oIyester or similar flexible transparent fabrics in question. ■ ·

The layer 44 can generally be composed of a photoconductive insulating material Made of material that is suitable for xerography purposes is. Such materials are selenium, glass, sulfur or aniicaaen and other organic photoconductors as well as distributions of photoconductive dyes such as zinc oxide and various Resins or other insulating binders. The layer 44 consists generally made of a good insulator that holds a surface charge in the dark but becomes conductive when it is Visible light, tinting radiation or other forms

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is exposed to active radiation.

The carrier 45 is insulating compared to the photoconductive one Layer 44 conducts well, and consists of materials such as aluminum, brass with paper or glass, with a conductive Cover is provided.

In order to apply a charge corresponding to an image to the thermoplastic layer, an object 46 is projected onto the photoconductive layer 44 via an objective lens 47 and a diaphragm 48. The sequence is controlled diirch a switch which opens the shutter 48 and at the same time a voltage source 50 to the conductive layers 41 and switches. The areas of the photoconductive layer 44 which are exposed to the light coming from the object 46 become conductive, whereby charge flows from the conductive layer 45 to the layer 44 and over the liquid layer 43 2 to the surface of the thermoplastic layer 40. The charged layer 40 can be removed from the arrangement and, as described above, dried by the addition of heat or a solvent in order to produce the deformations corresponding to the image.

The charge transfer by means of a liquid is compared with the method according to the US patent application Ser .l \ To. 193 273 critical to a far greater extent. If the liquid is practically insulating, there will be too little. Transfer charge,

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As a result, the subsequent development of the thermoplastic layer did not provide sufficient pictorial deformation. If the resistance of the liquid kexts layer is too low, then cross-flows of charge occur and the charge transfer becomes uncontrollable, as a result of which the resolution of the pictorial deformations to be developed becomes poor. It has been shown that a thickness of the 1 " ¹ IuSsIgICeXtSSChXClIt of 1 to 5 / U, in particular of 2 / U, is favorable. Smaller thicknesses lead to uneven discharges, while larger thicknesses require higher voltages. The more precise process of charge transfer is more complicated than was described here, but the simplified model is sufficient for the process shown here. "..". ■; -., - ■ "-".

If the charge transfer to ax deformable thermoplastic ¹ layer-add a. Developing a matt image can reduce the amount of charge if liquid remains on the deformable layer during the development through the supply of heat. For this purpose a liquid that cannot be vaporized is suitable. However, liquids must be used which are chemically compatible with both the thermo-plastic layer and the ΙΌΐο-conductor. A suitable liquid exists for use with the Staybelite layers . Polymethylsiloxansilicon of liquid with a viscosity of 50 Centist-akes and bis (Iributylzinn) -oxyd as a dopant This liquid over- a - ■ -..

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carries positive and negative charges, enables high resolution and has a non-destructive effect on the matt image. Als-Do- ' Other tin compounds can also be used will. However, the striking similarity) in the structural formulas of dimethyl polysiloxane and up to (tributyltin) oxide a partial explanation for their solubility

possibility and its applicability for the procedure according to the Invention. .

Although the mechanism of charge transport in dielectric " Liquids has not yet been precisely clarified, it is assumed that that possibly apart from highly pure, liquefied noble gases, the charges are coupled to molecules through the Move liquid. From this point of view, the dopant forms particles which propagate through the liquid can move and positive and negative charges through it transport. How the facts are also theoretically may, it has been experimentally proven that charge from the · ■ Edge layer between photoconductor and liquid to the edge layer between liquid and charge-absorbing layer is transported where it is held. The separation the charge-receiving layer then enables the electrostatic image to be developed, for example as a matt image.

The amount of time required for charge transfer depends the effective conductivity of the liquid being transferred, ab · Liquids with relatively high conductivity, such as

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"For example, the above-mentioned bis (ü} ributyltin) oxide containing, transports charge from the photoconductor to a matt developable one charge-absorbing Soh.i-0.n fractions of a Second. For liquids with lower conductivity is the time is greater. The cargo transport continues after completion the exposure continues to a lesser extent when the substrates only electrically, are connected. It is therefore often advantageous to maintain a field after exposure is complete, so that a stronger charge transfer takes place, liquids with lower conductivity are sometimes advantageous, because in these there is a lower charge movement, whereby higher image resolutions are obtained. · '

4 shows the relationship between the image resolution and the time between the end of exposure and the start of the thermoplastic heat treatment. The parameter is -i the liquid used. A part of this time interval is used to complete the charge transfer. ! The remaining time interval represents the duration between. the separation of the thermoplastic layer from the photoconductor and the time required for the heat treatment, in which the charge transverse movements take place, whereby the image resolution is reduced after increasing resolution or decreasing J.eitfiuii ^ since.: bit ^^ ributylsinnO-pxyd 0,4 fo,

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bis (tributyltin) oxide 0.2 fo, bis (tributyltin) oxide 0.08 #, dibutyltin dilaurate 0.4 $. Another tin compound to the! Tetrabutyltin is used to produce relatively low conductivities. Curves A and B apply to relief images, while curves 0, D and E apply to matt images. ■

As can be seen from the set of curves for the various liquids, the resolution in line pairs per millimeter has a maximum of less than 1 minute and decreases with increasing charging time. The maximum of the charge transfer for the different doped insulating liquids is between 0 _,; 2 and 0.4 seconds. The maximum resolution is around 1 minute.

As stated above, there are special dopants-for certain Liquids cheap and unfavorable for others. It has been shown that if the formulas match the Dopants with those of the liquids have a greater Solubility for the dopants exists, whereby the Charge transfer properties are improved. For example igt bis (tributyltin) oxide for a silicone fluid with a viscosity of 50 centistokes it is okes unsuitable for a SÖ icon liquid of 60 Gent •is, : _ . ,

The invention created new processes and substances for an optimal charge transfer with liquid layers

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specified. The resulting effects are in charge-transferring Arrangements can be exploited. Apart from the specified liquids and dopants are still suitable other materials not specifically listed here for the stated purpose. It can with the invention "Process generally dielectric fluids with suitable Physical properties are used whose intrinsic resistance is too high for a charge transfer. By Addition of a suitable amount of doping material can reduce the resistor in a suitable and reproducible manner Value that is suitable for charge transfers is.

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Claims (1)

- '24 - "■■■ .- ■ U97221 Patent claims s M J Method for the transfer of electrical charges a surface of an electrically insulating, charge-receiving Layer, characterized in that "that between the applied on a conductive substrate electrically insulating charge-receiving layer and a charged layer Carrier layer, in which between the conductive substrate and the charged carrier layer for a specified ' When an electrical connection is established, a coupling layer is used, which consists of one, and one for degradation their β-resistance to one for charge transfer liquid of high electrical resistance containing suitable value doping material consists" That the same can be used ■ * ■ 2. A method according to claim 1, characterized in that as dopant sto ^ _t as dibutyltin dilaurate, bis (tributyltin) -oxyd, glacial acetic acid, trifluoroethanol, m-Aminobenzoltrifluorit, trifluoroacetic ^ methyl trifluoroacetate, TetrabutylKinn and mixtures thereof. 3 »Method according to claim 1 or 2, characterized in that that-to? Imprinting a charge on the substrate as a voltage source is switched between the individual layers. 909819/0993 4. The method according to claim 1, 2 or 3, characterized in that J that the substrate is provided with a latent, charge image « 5. The method naoh the preceding claims, characterized in, that as a charge-absorbing layer a deformable & re plastic layer is used. 6. The method according to the preceding claims, characterized in that that a photoconductor is used as the substrate «| 7. The method according to any one of claims 1 to 6, characterized by that as a charge-transferring liquid with Up to 0.4 ü-ev /.- ^ dibutyltin dilaurate doped silicone oil is used will. . ■ " 8. The method according to any one of claims 1 'to 6, characterized in that that as a charge-transferring liquid a ' Silicone oil doped with up to 0.4% by weight of bis (tributyltin) oxide is used. ο Method according to one of Claims 1 to 6, characterized in that a silicone oil doped with glacial acetic acid is used » '10 .. Method according to one of Claims 1 to 6, characterized in that that a silicone oil doped with Tetrabutylss.inn is used as the charge-transferring liquid, " 9098 19/0993 11. The method according to any one of claims 1 "to 6, characterized in that fluorocarbon doped with at least 0.001% by weight of trifluoroacetic acid is used as the charge-transferring liquid. 12. The method according to any one of claims 1 to 6, characterized ', that fluorocarbon doped with dimethyl trifluoroacetate is used as the charge-transferring liquid will. 13 »Method according to one of Claims 1 to 6, characterized in that that fluorocarbon doped with trifluoroethanol is used as the charge-transferring liquid. 14. The method according to any one of claims 1 to 6, characterized in, that fluorocarbon doped with m-aminobenzene trifluorite is used as a charge-transferring liquid finds. BAD OfVGiNAL '9Ö981970993