DE1472915A1 - Process for the preparation of photoconductive surfaces - Google Patents

Description

"Process for the preparation of photoconductive surfaces"

The invention relates to a method for preparing photoconductive surfaces.

Photoconductive surfaces for the production of xerographic images usually contain one Photoconductor that is vapor-deposited on a surface or applied in the same way as it is to it. But it can also A fine-grain photoconductor can be embedded in an insulating, film-forming mother layer. In this The photoconductor is able to trap an electrical trap

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Carry charge that can be changed by exposure to a picture or the like. The one made in this way electrostatic image can be removed by touching the surface with developer particles that carry the correct charge, be wrapped.

Photoconductor surfaces of this type can be used in many ways. They are used to produce visible images, the molding of printed pieces or the manufacture of printed circuits. In various processes, the Photoconductor surface used in various ways to get to the desired object.

It is known to form an image on a photoconductor and then develop the image with a masking developer, which is able to prevent attack on the photoconductive layer in the layers below the cover, so that the rest of the photoconductive layer can be removed by dissolving or etching it away.

The invention relates generally to such a process, but has a much wider field of application and can be used wherever a photoconductive layer is to be removed in order to carry out etching or other work to gain access to the area below.

The process of preparing photoconductive surfaces According to the invention, there is an invisible electrostatic image on a photoconductive surface is generated that as-then the electrostatic is not visible image is developed with a first liquid developer, at least a portion of which has an affinity to the charged area of the non-visible electrostatic image "drawn on and on it should be noted that hereafter, while the first liquid developer on the photoconductive surface bl * ;. b, -, these with a second liquid developer; .- *

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that cannot combine with the first liquid developer, after which the photoconductor is touched by an offsetting agent accepted by either one of the fluids and that the dissolved parts of the photoconductor are removed.

In one exemplary method, the second liquid does not contain the same as the first liquid developer is miscible, a dissolving agent for the photoconductor, so that when this liquid is used the photoconductor dissolves where it is touched by the liquid.

Another method is to apply the dissolving liquid to the surface after applying the second liquid upset. The dissolving liquid is chosen so that it is only attacked by one of the liquids, to connect with her and the photoleita is there to decompose where it is touched by the dissolving liquid.

In the process, when a pure liquid developer is used, the development evidently takes place by that the first liquid carries a different charge compared to the electrostatic image, so that the liquid is attracted to the charged areas of the image, and that is why, if, during the first Liquid is held in place, the surface is touched by a second liquid, which with the the first liquid is immiscible, the second liquid is deposited on the areas that are unaffected by the first liquid contained, so if the second liquid is of the dissolving type or a dissolving type Medium carries, or if in consequence a dissolving medium

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one of the liquids is added, which: with This medium is miscible, the photoconductive surface at the points where the liquid is so changed that it can be easily removed.

To protect the first liquid against removal during the subsequent application of the second liquid the two processes become so fast. executed that the first liquid is prevented from leave the area concerned. The conditions here are of course such that the electrostatic image it is not marred if the first liquid is an insulator and the electrostatic field attracts the first liquid holds its place.

About the sticking of the first liquid after it has settled To facilitate this, this liquid can be of high viscosity, for example a silicone, and thus have the tendency to to stay in their position. However, a developer medium can also be applied with the liquid and be deposited together with it to hold the liquid in place in this way. In this In the trap, the developer material is preferably of a nature that it absorbs the liquid around it better to hold on.

After the deposition of the second liquid and the dissolving medium, the surface it acts on can be weighted or washed away in any way. It will be found that, using the invention, photoconductors such as selenium or zinc oxide are easily removed by the use of a solution of 5 to 10 % sodium hydroxide, sodium sulphide or sodium hydroxide in ethyl alcohol or methyl alcohol or diacetone or some other higher alcohol.

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The invention is not restricted to the substances mentioned but can be used together with any suitable ones Substance can be used with advantage.

A preferred embodiment of the method consists, for example, in that a zinc oxide or a selenium coating is made on paper or metal in the already known way, then charged and with a Image is exposed so that an electrostatic, invisible image is contained on the surface. This picture will then developed with a developer that creates a developer liquid with a boiling point and high viscosity

whose electrical resistance is higher than 10 'ohm cm and whose dielectric constant is less than 5 which may contain a fine-grained material, for example resin or the like, or a resin or a other binder together with pigment powder. The resin or the corresponding substance are preferably chosen so that they absorb some insulating fluid and hold it in place during the subsequent process.

After developing the picture in this way and for so long If the picture is still wet, a mixture is applied to the surface that contains a polar substance, such as alcohol and contains an insulating liquid which may be the same as that used for the first part of the method was used. However, these two liquids must not be miscible, so that the polar liquid differs from the insulating liquid is repelled, which sits on the picture and only the remaining surface is moist hold is able. A caustic medium can be added to the alcohol so that the photoconductive surface is dissolved there where the corrosive acts on them. The method can also be continued so that the area of a corrosive mixture in alcohol or in another

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polar liquid is dissolved after being exposed it was first treated with the mixture of polar and non-polar liquids.

The disintegrated area can then be removed simply by using mechanical means, for example by • in a jet of water or an abrasive as it turned out has that the dissolving effect made the surface easily removable.

In the case of using selenium, one becomes of the need relieved of using carbon disulphide as a solvent. The procedure becomes much safer and better this way.

To better understand the invention, various embodiments of the method are described below, reference being made to the drawings. It is understood that variations of these embodiments are within the limits the invention remain as it is designated in the claims.

The drawing explains two options for carrying out the process using the process steps.

1 shows a simple method option with a small number of method steps.

In the first step, a photoconductive layer 2 carries a charge 1 on the base 3, The photoconductive layer is of known form, such as a vacuum deposition of selenium on a base, or a zinc oxide photoconductor, which is in a resin film or the like. embedded and mounted on a thin stump made of aluminum or paper or some other material. The charge is applied in any manner, for example, by first the photoconductive surface to a corona discharge and then the exposure through a negative exposes a

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To get invisible electrostatic image according to the template.

The second step is to develop the invisible electrostatic image. For this purpose, a first liquid is used With the help of the roller 4 · applied to the surface. The roller is permeable and carries the necessary developer liquid with it. A developed image 5 is therefore created on the photoconductive surface 2, which is held on by the charge.

In the third step, the second liquid 6 is applied, preferably using a roller 7, which the Carries liquid. The wetting of the photoconductive surface by this liquid takes place in those areas where the developer 5 was not attracted and not retained on the photoconductor surface. For this reason, the Both liquids must be immiscible, so the first applied liquid 5 controls the deposition of the second liquid 6.

In this case, the liquid 6 contains a photoconductor dissolving agent, which is why the photoconductor after application is resolved. In process step 4 it is then shown such as a jet of water or some other liquid applied with sufficient force, the second liquid and the dissolved photoconductor are removed.

A beam or a brush is marked with 8, and the surface from which the photoconductor is removed, transmits' the indicator. 9

Although the jet can remove both liquids, the first liquid 5 and the second liquid 6, but since the First liquid 5 does not contain any dissolving agent, it is obvious that the photoconductor, as far as it thereby

is protected, not touched, and therefore during 909817/0611. 8th-

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the flushing operation, even if both liquids be removed, one area is freed from the photoconductor because of the dissolving effect, while the other Area holds the photo conductor.

In this way, of course, an archetype can be produced in a simple manner, for example by using a Underlay made of aluminum or plastic or made of film provided with a photoconductive surface, the process allows that the original image is produced without gaps according to the "full-wet" (allwet) process by adding the first liquid is simply applied to the developed image and then the second liquid, which is the dissolving agent contains, is applied, after which, after dissolution has taken place, the liquids by washing off, wiping off or the like. Removed, whereby the archetype arises. The archetype has areas in which the aluminum or the plastic is exposed and areas where the photoconductor stays in place. Determine the latter areas an image that can be used directly in offset printing or other processes as desired.

The advantage of this process is that there is no drying between the individual process steps and that the procedure can be carried out in the shortest possible time.

Another possible method is shown in FIG. Method step 1 shows the invisible electrostatic ^{image 10 on a} photoconductor 11 on a base. Step 2 shows how the roller 13 applies the developer 14 to the invisible electrostatic image 10. In method step 3, the second liquid 16, which in this case can quite simply be a polar substance, is applied by means of the roller 15. The first developer 14 was an insulating liquid; in the present case both liquids were applied to the

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Area according to the original template of the electrostatic Image captured. In process step 4 one can see how a dissolving liquid 18 can be applied to the surface by means of a roller 17. In In this case the dissolving liquid naturally has an affinity for or a solubility in the liquid 16, so that it is absorbed or retained by this liquid and thereby causes the liquid is transformed into a dissolving agent that acts on the photoconductor in the area concerned. In the process step 5 finally, liquid and photoconductors are removed from the area 20 by means of the jet 19, while region 21 holds the photoconductor in place due to the protection provided by liquid 14.

It is obvious that when using this additional process step and primarily when using two more selective liquids on the photoconductor surface, the dissolving Means can be selected to be miscible with the liquid 16 or else with the liquid 14 and that it therefore, instead of being absorbed by the liquid 16 as shown in Figure 2, it is absorbed by the insulating liquid 14 can be absorbed, so that the opposite areas of the photoconductor surface are removed in each case will.

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example

A sheet of paper, plastic, metal or another material is initially used as a base with a provided photoconductive surface, which has the following composition:

Photoconductive zinc oxide 100 g

slightly saturated alkyd resin 30 g

Coloring agent, Bengali pink 0.1 g

Dye, sodium fluorescein 0.01 g

Dye, brilliant green 0.01 g

Dryer 0.02 g

ToIuen 50 g

After 6-8 hours of drying at 60 ^° C., the coating is ready for use in the optional method according to the invention. At a field strength of 25.4 KV / cm, the sheet is electrostatically charged, creating a surface charge that corresponds to a 300 V potential.

The sheet is then exposed to the desired object and developed in a developer composed as follows:

Shellsol T 90 parts by volume

(liquid hydrocarbon
the Shell Company)

liquid silicone 10 ". "

(e.g. Dow Corning Silicone
fluid, viscosity 200 cps).

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These ingredients are mixed together to form a liquid developer, from which the liquid silicone is applied Image areas · settles and leaves a viscous image.

The sheet is developed either with the image surface after down in a metal bowl or with metal rollers, so that there is a maximum of support in the areas of greatest density. Do this in the bowl Requires 30 seconds to 1 minute or four times rolling with the roller. Then the damp sheet is covered with clear Shellsol T rinsed to remove the excess and while still wet placed in an emulsion of Shellsol T and water, which the following Composition has:

Shellsol T 60 ml

Water 4-0 ml

Dampening agent, Nonidet T

P-40 (Shell Company) 1 ml.

These liquids are vigorously shaken in a vessel _f so that an emulsion is formed. This emulsion causes the optional wetting of the image areas with Shellsol T and the non-image areas with water.

The still moist sheet is now in for about 20 seconds immersed a bath made up of a 10% solution of potassium hydroaqyd consists in ethyl alcohol. Here the photoconductor is in the water-containing non-image areas, where the dissolving Agent mixes with the liquid already located there, dissolved. Then the sheet is out of the bathroom

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taken out and in a water bath or under a water jet, the coating of the non-image areas is washed. For the purpose of printing, the sheet is then with a humidifying agent, for example with a 5% sodium orthophosphate solution in water or a. . 50% solution of a commercially available 3? 1atten dissecting agent, moistened and then with color for the purpose of printing Mistake.

Arranged on a metal base, the sheet can now be partially and deeply etched for use as a printing block and also to form small pieces from thin metal sheets.

Example 2 SSSSSSSSSSSSS3SSSSS

This example is similar to Example 1, but instead of the insulating liquid developer (silicone liquid) first made a concentrated developer, which has the following composition:

Monolit Eot: 100 g

Lithograph varnish 200 g

Pentacite P423 rubber 100 g

Cyclohexane 20 g

The concentrate is mixed together in a billet mill, where a paste is made. Meses concentrate is in Shellsol T or any other hydrocarbon solvent dispersed, for example a flash point 'of 57 ° C and contains O-hydrocarbons. The mix

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The ratio should be 1g paste to 100 g Shellsol T.

The developer is then used as in Example 1. He is a first developer who adheres a little more firmly, but who in turn has the effect of the image before the action of the shield second liquid

Example 3

According to Examples 1 and 2, an aluminum sheet can be etched after the image has been applied and the coating has been removed in order to produce a metal part by etching «The etchant can be, for example, a 10% hydrofluoric acid.

example

In Examples 1 and 2, the sheet can be a glass There are bases coated with zinc oxide, bismuth trioxide, lead iodide, cadmium sulfide, cadmium selenide or the like is. After removing the coating from the substrate in the non-image area, the glass can be selectively etched with hydrofluoric acid will.

Example 5

In example 1 or 2 a brass leaf can be used

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and after the selective removal of the coating, the sheet can be selectively coated with gold, chromium, silver, nickel or the like be electro-plated ..

Example 6

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The sheet of paper, plastic, metal, wood or other material can be placed in a vacuum chamber with a thin coating of amorphous, photo-insulating selenium or sulfur or arsenic trichloride with a thickness of "for example 0.5 5 micron coated. Then the sheet is charged and developed with a developer according to Example 1 and 2, for example by replacing the Monolith Hot with Mikrolith Schwarz CT and the Shellsol T with mineral turpentine (4f>% aromatics) is modified. Then the sheet selectively moistened in an emulsion which has a similar composition as in Examples 1 and 2, but which, if desired, it can be modified by using Teepol as a substitute for Nonidet. After selective humidification The plate can be more caustic to remove selenium from non-image areas by using a 10% solution Advertise soda treated in water or methyl alcohol. Then the sheet can be used for similar lithographic purposes or can be used as a printing block or for transparent reproduction.

Example 7

In Example 6, the selectively dissolved selenium plate

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have a glass or film base. After removing the selenium from the non-image areas as well as selectively from the seamlessly tinted surfaces create a transparency that has a strong ability to dissolve.

Example 9

In example 6 the base can be made of glass and the developer according to example 2 can contain ceramic powder with flux. After their completion, these powders can be burned onto the glass by heating in an oven, for example to 800 ^° C.

Example 10

The sheet of paper, plastic, metal, wood or other material can be dipped or by vapor deposition in a vacuum be covered with an organic photoconductor, so that a plate is created, as it is made by Kalle AG, Germany, is distributed. This sheet is charged, exposed and developed with a developer according to Example 2, which, if necessary, by the use of Peerless carbon black instead of Monolite Red and changed to Shellsol T is dispersed. The emulsion that is used in example 2 for selective moistening can, if desired, can be modified by using a petroleum distillate (white spirits) and water together with a suitable carrier, for example Teepol, or triethanolamine Oleate can be modified. With the selective

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Removal of the organic photoconductor coating is a solution of 5% sodium hydroxide in water for a time of Applied 10 seconds to the organic photoconductor off. remove the non-image areas. Then the plate can used in lithography.

Example 11

In Example 9, the sheet can be made of aluminum and the end product becomes a piece formed by etching when it is diluted 1 - 10 % in water with hydrofluoric acid.

Example 12

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In Examples 1, 2, 6 or 8, the sheet may be multilayered with a printed circuit board, and the copper sheet contained thereon may be etched by etching with ferric chloride or acid or the like after the selective removal of the photoconductor. Then in the desired areas of copper conductors can be formed where the completeness ^and edge sharpness is maintained in an improved manner.

Example. 13th

In examples 1, 2, 6 or 10, the sheet made of fabric,

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Cotton, wool, synthetic fibers and. like. "exist and the fabric can be selectively dyed or printed.

From these examples it can be seen that our process in the exposure and development of a surface is modified which carries an oleophilic image while it is wet, consists in selectively moistening the sheet with another Liquid, in the subsequent selective dissolution or Disintegration of the coating in fixed areas, so that a selective barrier to a subsequent attack or a post-treatment of the underlying sheet is built up.

Example 14

In the removal process according to Example 2, instead of the potassium hydroxide solution in ethyl alcohol, a solution of! Your in xylene is used, which selectively softens the image areas that are moistened by water. After the moistened sheet has been heated to 65 ^° C. for one minute, the softened image areas are washed off with xylene,; '-Cumolj ^ mineral turpentine or the like. Removed.

Example I5

In Example 6, in which a thin layer of amorphous selenium is the photoconductor, the solution is potassium hydroxide in ethyl alcohol replaced by a solution of

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Potassium sulfide or sodium sulfide in a higher alcohol or replaced by carbon disulfide.

Example 16

In example 10, where the photoconductor layer is an organic photoconductor, the potassium hydroxide solution is through replaced by a solution of benzene or highly aromatic solvents.

Example 17

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The sheet covered with zinc oxide resin is charged,
exposed and developed with the following developer:

Water soluble gum (e.g. starch) 10 g
Shellsol T, hydrocarbon solvent 50 g.

These substances are ground together to form a paste and then dispersed in Shellsol T in a ratio of 1 g paste. to 100 g of Shellsol T. This dispersion is used to develop the image, the gum falling on the areas containing the charge and the hydrocarbon solvent wetting the remaining areas. The leaf is then exposed to the water (which the
second liquid in this process), which represents the

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water-soluble gum dissolves and falls in its place. The non-image areas that were created with Shellsol T are moistened, unaffected by the washing process, and these areas will then withstand subsequent attack with acid. The image areas moistened with water are now exposed to an acid, for example a 30% strength Acetic acid, which mixes with the water and dissolves the zinc oxide. The sheet can be selectively colored and, where necessary, be subjected to a further resolution, for example to '. Etching a glass base.

Example 18

Replaced in example 17 where the photoconductor is zinc oxide strength can be obtained from acaeien resin, tragacanth gum, ethyl cellulose and the like

Example 19

In example 17 "where the photoconductor" was replaced by selenium, the rubber is replaced by potassium sulfide. This is ground to a fine powder and in a similar manner dispersed in the rubber. When moistened with water, the potassium sulfide attacks the selenium and enables it to be removed.

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Example 20

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In Example 17, the photoconductor is through an organic Photoconductor replaced, ζ, B. by poly (n-propenyl carbazole) and the gum is replaced with an organic acid, e.g. through palmitic acid, lauric acid, myristic acid and the like dispersed in a hydrocarbon solvent with a high boiling point or in silicone oil or ParaJELnÖl or the like.

Example 21

In any of the preceding examples, the caustic solution or the like is replaced by the solution of a ketone, e.g. 1: - 10% acetone in water.

Example 22

In the previous example, the ethyl alcohol or Like. Replaced by a solution of an aldehyde in alcohol or. Water e.g. a 1% solution.

Example 23

In the previous examples, where the coating is resin-bonded

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den is, or is an organic photoconductor, becomes the Ultimate solution or the coating replaced by a solution of Chlorethane (Chlorothene) in alcohol.

Claims : 909817/0611

Claims (16)

Godfather not claimed 1)! Process for the preparation of photoconductive surfaces, characterized in that on a photoconductive surface a invisible electrostatic image is created that the invisible electrostatic image with a first developer is developed, which at least partially has an affinity for the charged areas of the invisible electrostatic image, causing it to be drawn there and held on becomes that while the first developer liquid adheres to the photoconductive surface remains, the surface is moistened with a second liquid that is with the first "liquid is immiscible, the photoconductor being treated with a dissolving agent through contact that selectively belongs to and is accepted by one of the two liquids, and that the photoconductor is removed where it has dissolved. 2) Method according to claim 1, characterized that the second liquid contains the photoconductor dissolving agent. 3) Method according to claim 1, characterized that the dissolving liquid is used after the second liquid, but that it is selective with only one of the both liquids can be combined in order to dissolve the photoconductor where it is »09-817 / 061 1 is touched. 4) Method according to one of the preceding claims, characterized in that the liquid developer an electrically insulating Liquid is that has an affinity for the charging areas of the non-visible electrostatic Image has, which is why she is attracted to it and captured on it. 5) Method according to one of the preceding claims, characterized in that the first developer contains an insulating carbon-hydrogen liquid in which a liquid Silicone is suspended, which is attracted to the invisible electrostatic image. 6) Method according to one of the preceding claims, characterized in that .the second liquid that coincides with the first liquid immiscible "is a polar liquid. 7) Method according to claim 6, characterized that the second liquid is the emulsion of a carbon-hydrogen with Water is such that the image areas are wetted with the hydrophobic liquid and that the non-image areas are hydrophilic. 909817/0611 8) Method according to claims 1 and 2., D a through characterized in that the first developing liquid contains an electrically insulating carbon-hydrogen liquid in which fine-grained matter is suspended, which is attracted by the electrostatic image, and thus the adherence of the carbon-hydrogen -Liquid on the image areas during the application of the second so that it cannot be mixed Liquid supported and caused by the fact that the second liquid only wets the non-image areas. 9) Method according to claims 1 and 2, characterized in that the first developer liquid contains an electrically conductive liquid that acts as a carrier for small particles which are attracted to the image area and which hold the liquid on the image area, as long as the small particles are held there. 10) Method according to claims 1 and 2, characterized in that the first developer liquid an electrically conductive • liquid that acts as a carrier for small particles which are attracted to the image area and which the liquid only while on the image area hold, as the small particles linger there, and that this liquid also the Non-areas moisturizes that further, while the first developer is present on the non-image area is, the ^ lrche with a second liquid, the SG9817 / 0611 which is immiscible with the first liquid, is wetted, whereby the developer particles removed. 11) Method according to any one of the preceding claims, in which the invisible image is on a photoconductor surface is formed with an etchable base, characterized in that After removing the pot conductor, in the places where it is dissolved, the base n, n of the Photoconductor-free areas are etched. 12) Method according to claims 1 to 10 with a not "nc visible image on the photoconductor, the supported by a pad, thereby characterized in that after removing the photoconductor, there v / o it is dissolved, a layer is applied to the base in the places where the photoconductor has been removed. 13) Method according to the preceding claims, characterized in that the photoconductor is an organic photoconductor and that the second liquid contains an alcohol, so that the photoconductor is dissolved. 14) Method according to claims 1 -12, characterized in that the photoconductor is an inorganic photoconductor and that the second liquid is an alcohol and caustic potash) so that the photoconductor is dissolved. 909817/0611 15) Method according to claims 1 -12, characterized characterized in that a photoconductive selenium fish is used and that the second Liquid contains alcohol and caustic potash so that the selenium is dissolved. 16) Method according to claims 1 -12, characterized characterized in that after the application of the first developer and the second liquid, an alcohol or an alcohol and caustic potash placed on the wet surface to selectively step to one of the liquids, so that the photoconductor is dissolved in this area. 909817/061 1