DE1497145C3 - Electrophotographic recording material - Google Patents

Description

1M97 145

finely divided copper (II) _-yerbindung; Consists of copper (II) sulfide, copper (li) selenide, copper (II) ^ hydroxide, copper (II) oxide, copper (II) carbonate, basic copper (H) carbpnati copper (ill) phosphate , Copper (II) arsenite, copper (II) oxalate, copper (II) oleate or copper (II) stearate, with; a solution of an organic binder, mixed and then the resulting mixture as a coating on ... a, carrier, applied. In a light-sensitive layer of zinc oxide in a light-adjusted state, the adsorption of oxygen on the surface of zinc oxide is prevented by certain factors; die.by a binder; delayed recovery calm down; , probably on the mechanism by which the functional group in the binder is absorbed on the surface of zinc oxide in place of oxygen or scavenges the oxygen.

It is believed that the copper (II) compound the absorption progress after a certain Mechanism promotes. Although it is not yet clear whether some of the copper (II) ions are partially present in the If the surface of zinc oxide is present or not, partial penetration or uptake of copper (II) ions can occur take place in view of the fact that by mixing zinc oxide and a binder with copper (II) ions in an amount of only 0.002 Ge-r weight percent, based on the zinc oxide, a considerable effect is produced.

The amount of copper (II) salt can be used to achieve a clear effect in the above Area lie. Resistance to exposure is achieved by increasing the amount of zinc oxide added amount reached. Even if a large amount of such a water-insoluble copper compound is added the other electrophotographic properties are hardly affected. The zinc oxide Copper (II) ions can be added in an amount up to about 20 percent by weight.

The phenomenon of fatigue is known to depend on the surface layer of a photosensitive layer away. According to the invention, the photosensitive layer can also be provided only on the surface layer with the lower layer free of the copper compound. In the case of a light-sensitive Layer with a thickness of about 20 microns is used if only the surface layer with a thickness of about 2 to 5 microns or above consists of a high fatigue recovery layer, the Character of the photosensitive layer is determined by the properties of the surface layer.

In the case of a binder with a hardening mass, the fatigue recovery is delayed in the usual way by hardening or solidification. However, the presence of copper salt can somewhat ameliorate this disadvantage. Among the copper (II) compounds, the copper (II) stearate additionally has the particularly advantageous feature that when it is added to the coating liquid containing zinc oxide particles, the precipitation of zinc oxide particles is prevented and a back dispersion of zinc oxide particles precipitated in the coating liquid is also easily obtained , thereby improving the stability and durability of the coating liquid; that is, a large amount of cupric stearate makes the thixotropic liquid liquid, and difficulties may arise in some coating operations. However, when used appropriately, the sedimentation _; of inorganic pigments : such as zinc oxide, prevented, which improves the resistance of the coating liquid to the coating liquid: therefore, the stearate is preferably used together with a

•; 5 other copper salt ^used; : to: achieve two or more advantages and improvements at the same time '. Combinations of two or more other copper (II) salts can also be used advantageously. , ·

IP Since the copper connection improves the dark dampening character, it is also possible to add a material which itself has a deteriorating effect on the throwing dampening property, e.g. a: sensitizer, the addition of which is undesirable for this reason. ''"'■ - ■■■■' ■ . '"" ■: ■ · ■ -; ■ '■■''- ■ This is shown below in Examples 4 and 5, wherein the presence of the copper compound eliminates the disadvantage that occurs when using aluminum stearate alone, with aluminum stearate

ap increases the dispersibility of a pigment, however, the dark attenuation character deteriorates. A similar effect can be achieved when used together can be observed with a sensitizing dye. . ■

Another advantage of the electrophotographic layer according to the invention is that it not only generally for copier purposes in the office, but also for embossing or marking purposes can be used.

3P The invention is explained in more detail below using examples.

Example composition A

Parts by weight

Photoconductive zinc oxide powder 100

Soy type alkyd resin varnish (soy modification, oil

length 40%) 30

(non-volatile 50%)

Silicone resin varnish with a low degree of polymerisation 30th

(non-volatile 60%)

Cobalt naphthenate 1.0

Methyl ethyl ketone peroxide 0.5

Toluene 20

The above composition was placed in a porcelain ball mill and placed in appropriately ground.

In the composition was 0.02 parts of copper sulfide introduced to obtain Composition B. The two masses became expedient diluted with toluene and sprayed onto a soft steel plate coated with a top coat, to obtain a coating layer of 20 microns.

-After standing for 2 days at room temperature the plates were left in a dark place for more than 10 hours, after which they were one

1/4197

• Subjected to corona discharge in a dark place - Have been,! The electrophotographic: properties were determined, whereby the following results were obtained. In addition, after issuance A pre-exposure examines the recovery characteristics. . . , ■ · ■ '■' ■

• ■! The following properties were found:

A. B. Initial surfaces potential. . . . . . ; . . . . . . . 450 to 450 to. 500VoIt 500VoIt Half time for Dunkeldämp fung i ... 6 to 8 to 8 min 9 min Relative sensitivity for xenon light 100 70 Initial potential at Be charge after pre-exposure with light from ,. 5000 lux from a fluo- rescens lamp during 5 min and standing in line a dark place rend 2 min (5000 lux off a glow lamp) .... 70 to 250 to 80 volts 300 volts

Initial surfaces ■ - ■ c ■ ■ ·. . D, ■: potential 450 to 450 to Half time for Dunkeldämp 500 volts 500 volts fung ............: approximately approximately IO Relative sensitivity 5 min 7 min for xenon light. Initial potential according to Be 100 90 clearing with light from 500 lux from a glow 15th lamp for 5 min and standing at one dark place during 5 min 100 to 400 to 20th 150 volts 460 volts

3O

In Composition B, the sensitivity is slightly lower, but this is the case in the practical Use is without disadvantage. The recovery or recovery from fatigue is there faster in the composition A.

Example 2

Similarly, compositions or compositions C and D given below were obtained uniformly mixed and ground and applied to an original paper on which polyvinylpyrrolidone has been applied as an undercoat; the masses C and D were each in a layer thickness from 15 to 18 microns (on a dry basis) applied and dried.

Composition C

Parts by weight

Photoconductive ZnO powder 100

Silicone resin varnish (non-volatile material 80%) 18

Styrene-modified alkyd resin paint

(non-volatile material 50%) ..... 32

Toluene 10

Methyl ethyl ketone 10

Composition D

Composition of C with another addition of the following components:

Parts by weight

Copper (II) stearate 0.2

Copper (II) oxalate <.... 0.2

Example 3

Similarly, the two compositions given below were based on an aluminum plate in a layer thickness of 20 microns ( on dry basis) applied:

Lead chromate 15 parts by weight

Composition E

Parts by weight

Photoconductive zinc oxide 100

Polyvinyl butyral 45

Toluene 60

Ethyl acetate 120

Isopropyl alcohol 20:

Composition F

Composition E with a further addition of 0.015 parts by weight of copper (II) oxide.
The following properties were found:

Initial surfaces E. F. 45 potential 220 to 250 to Half time for Dunkeldämp 250 volts 280 volts fung approximately approximately 50 Relative sensitivity 3 min 4 min for xenon light Initial potential after Vor 100 105 exposure to light from 500 lux from a glow 55 lamp for 5 min and standing at one dark place during 5 min 120 to 200 to 60 150 volts 220 volts

. In this case the cupric oxide acted like a sensitizer to some extent implemented.

B e i s ρ i e 1 4

A similar effect of promoting fatigue recovery through the addition of copper salt

was observed as with the two compositions according to Example 2, when these 8 ml of 0.5% Rose Bengal solution was added. Here the recovery or recovery was with the Composition of C faster with the addition of Rose Bengal.

; For example, 5

The following two compositions were made on 80 micron original paper applied in a layer thickness of 15 microns:

Composition G

Parts by weight

Photoconductive zinc oxide 100

Polybutyl methacrylate 10

Aluminum stearate 0.8

Silicone resin varnish (non-volatile material 60%) 21

Sulphonamide resin varnish (non-volatile material 50%) 10

Ethyl acetate 20

Toluene 20

Composition H

Composition G mixed with 2 parts by weight of copper (II) sulphate.
The following properties were found:

Steel plate applied to a photoconductive layer with a dry thickness of 15 to 18 microns to build. The properties of the layers are summarized in the table below, with the Results listed under 1, 2 and 3 by determination after placing in a darkroom were obtained for more than 10 hours. In addition, the storage stability of the coating liquid means that in the table

ίο is indicated under 5, the symbol »a« the case, in which there is almost no caking of the zinc oxide precipitate after the coating liquid is left to stand was observed in a closed vessel for more than 2 weeks and the formed Precipitations could easily be converted back into the dispersion. The symbol "b" denotes the case in which caking was observed and the redispersion of the Precipitation was difficult.

G H Initial surfaces potential 300 to 280 to 320 volts 300VoIt Half time for Dunkeldämp fung 1 min 2 min Relative sensitivity for xenon light 100 120 Initial potential after Vor exposure to light from 1000 lux from one Glow lamp during 5 min and standing in line a dark place rend 5 min 150 to 240 to 160 volts 260 volts

35

Example 6

The following compositions were made by mixing and grinding those listed below Components made in each case:

I. J 1. Initial surfaces potential 450 to 450 to 500 volts 500 volts 2nd half for dark damping 5 min 7 min 3. Relative sensitivity for xenon light 100 90 4. Initial surfaces potential according to plan clearing with light from 500 lux of a glow lamp for 5 min and standing while 5 min in a dark chamber 100 to 420 to 150 volts 480 volts 5. Storage stability "B" "A"

As shown in the table above, Composition I has difficulties or disadvantages with the properties listed under (4) and (5), while the composition J is in the properties listed under (4) and (5) as well as other properties as excellent proved.

Example 7

The following compositions were made:

Composition I

Parts by weight

Photoconductive zinc oxide 100

Silicone resin varnish (non-volatile material 60%) 18

Styrene-modified alkyd resin paint (non-volatile material 50%) 32

Toluene 10

Methyl ethyl ketone 10

Composition J

Composition I with a further addition of 0.4 parts by weight of copper (II) stearate.

The above-mentioned coating-forming liquid compositions I and J were each used as a coating on a composition K treated with a sandblasting blower (control)

Parts by weight

Photoconductive zinc oxide 100

Silicone resin varnish (non-volatile material 60%) 35

Phenol-modified alkyd resin varnish

(non-volatile material 50%) 18

Toluene 20

Composition L

Composition K with a further addition of 1 part by weight of copper (II) stearate.

Each of these compositions was coated onto high quality paper with an intermediate or Underlayer (substrate) of polyvinyl alcohol with a thickness of 60 microns in a layer thickness of 12 microns

crown applied on a dry basis. The results of the determination of the storage reliability the coating compositions and the properties of the photosensitive layers after drying are compiled in the table below:

K L. .1. Initial surfaces potential 320 to 340 to 360 volts 380 volts 2nd half for dark damping 5 to 6 to 6 min 8 min 3. Relative sensitivity for xenon light 100 100 4. Initial surfaces potential according to seal with light from 2000 lux of a glow lamp for 5 min and after standing in one Darkroom rend 5 min 100 to 370 to 120 volts 410 volts 5. Storage stability of the liquid sigen composition (without cobalt naphtha nat) "B" "A"

Example 8
The following compositions were made:

Composition M (control)

Parts by weight

Photosensitive zinc oxide 100

Epoxy modified alkyd resin (non-volatile material 50%) 55

Toluene 30

Methyl ethyl ketone peroxide 0.5

Composition N

Composition M mixed with 0.7 parts by weight of copper (II) stearate.

Each of compositions M and N was mixed with 10 parts by weight of a 10% solution of cobalt naphthenate in toluene immediately before coating and then placed on a steel plate as a coating under Formation of a dry film with a layer thickness of 30 to 35 microns applied. The drying was carried out by allowing the material to stand at room temperature overnight.

The following results were obtained:

1. Initial surface- '■ "-'' ^: • ■ M n ' ao potential 450 to 450 to 2. Half time for dark 500 volts 500VoIt damping 5 to 6 to 3. Relative sensitivity " ^J '■ 6 min 8 min for xenon light 4th Initial surface 100 100 potential according to plan clearing with light from 30th 2000 lux of a glow lamp for 5 min and standing in one Darkroom rend 5 min ^:. .- ■. 35 ■ 100 to 370 to Shelf life of the ' 120 volts 410 volts liquid cohesion setting (without addition of cobalt naphthenate) 40 "C" ("b") "A"

Claims (5)

to.heat.in a diinkle ^ place.Qder.a. negative patent claim: j ^ gf w Since the corona discharge itself is a recovery;: '·. ·::. ■ .. ■' - ■ .-: - 'a layer of' The unadjusted state to the electrophotographic recording material 5 brings about the darkly smacked state, it is with a ZnO binder layer which, based on the ZnO for the correct assessment of the degree of fatigue, contains between 0.002 and 20 percent by weight, a charge time-surface potential curve of a salt and which is free of organic absorption, instead of the initial surface potential of phosphorus compounds, can be measured by this. The gradient of the connection is contained in a dark-colored layer, which indicates that the ZnO binder layer has been left to stand in a dark place for a long period of time at least one water-insoluble Cu-II layer. ; ·.;. ; . '·. . ; Charging curve u is particularly high and the value of the saturation potential is high, while with a .. '". ·:" ■ · · ■ ·. ·. 'M:.: .. v':;:;. ■>. '. light-adjusted layer of the slope gradient.; . ... 15 is weak and the value of the saturation potential is low. : ··; ■. · ■ ·. '. The rate of recovery from fatigue varies greatly depending on the binder associated with the zinc oxide. Research has shown that silicone resin is most advantageous in this regard. The invention relates to an electrophoto, with many other resins, graphic recording material having a ZnO such as alkyd, epoxy, epoxy ester resins, mixed poly binder layer, based on on the ZnO, between merisate of vinyl chloride and acetate, acrylic acid ester, 0.002 and 20 percent by weight of a salt contains methacrylic acid ester, polyvinyl butyral, mixed poly and which is free of organic phosphorus compounds. 25 merisate of styrene and butadiene, sulfonamide and The properties of an electrophotographic polyketone and their miscible combinations, light-sensitive layer, which are disadvantageous from the photoconductive compared to silicone resin, d. H. the capable zinc oxide and an electrically insulating recovery rate is considerably lower, film-forming material is considerably lower. In the case of thermosetting or solidifying materials, the recovery rate is slower after the hardening is reduced by changing the film-forming material, the 3 ° resins as previously. A new one was flowing. Proposed method in which use was made of this for an electrophotographic material (cf. German features indicated below important. Auslegeschrift 1 294 198). 1. A high initial surface potential (potential ^{35. In} ^ f German Patent 1 249 691 is also ^{proposed immediately after charging by means of an} electrophotographic recording material corona discharge in a dark room), with a photoconductive layer 2. appropriately slow dark attenuation, ^m . * in ^a binder that is dispersed in a 3. Rapid light attenuation and low residual potential binder containing dispersed zinc oxide. This _t j _a j ro ₄₀ recording material ^is characterized by 4. No fogging during development. that it is in the photoconductive layer and / or in the intermediate layer has at least one organic phosphor Studies have been carried out on various phosphorus compounds. Binder compositions executed and thereby According to a further proposal (cf. German found that a considerable number of them (patent specification 1278 242) is said to be capable of being used for electrophotography. Superphical recording material at least one alidies has been found that the degree of influencing phatic monobasic or polybasic carboxylic acid with the feature (1) by irradiation with light in front of the water-solubilizing groups, their salt or charge, is considerably due to the special binding their reaction product with Contain ZnO,
agent composition is changed, and that therefore 5 ° the object of the invention is to provide an electronic, the following condition (5) must be added. trophotographic recording material with a 5. Practically eliminating the influence of ^ZnO f ^ίηα * ™ ^ ^lsc ^ ^die '. ^{On the basis of} - ^{the Z} ? ° 'the pre-exposure between 0.002 and 20 percent by weight of a salt and which are free of organic phosphorus A state in which the influence of 55 bonds is, this recording material the pre-exposure remains, is compensated with »light - a significantly improved fatigue recovery« denotes, while a state at points. which such an influence by storage on This object is achieved in that the ZnO- at least one water-insoluble binder layer in a dark place for a long period of time is avoided, referred to as "dark adjustment" contains 6o Cu-II compound. sird. The recording material according to the invention When a layer is in the light-balanced state it can be made in an effective and convenient manner (State of fatigue) of the corona discharge are under- compared with the known working methods, is thrown, the potential is low and the dark - in which a zinc oxide with an aqueous solution damping speed high. 65 of an inorganic salt is treated. In order to apply this material to the dark-blended electrophotographic recording material To bring state, it is effective, it can be made by at a dark- according to the invention len place to stand for a long period of time, one a photoconductive zinc oxide powder and one