CA1181626A - Aqueous composition-sensitive photoconductive composition containing zn0 or ti0 in2 xx and a photoconductive anthraquinone pigment - Google Patents
Aqueous composition-sensitive photoconductive composition containing zn0 or ti0 in2 xx and a photoconductive anthraquinone pigmentInfo
- Publication number
- CA1181626A CA1181626A CA000408553A CA408553A CA1181626A CA 1181626 A CA1181626 A CA 1181626A CA 000408553 A CA000408553 A CA 000408553A CA 408553 A CA408553 A CA 408553A CA 1181626 A CA1181626 A CA 1181626A
- Authority
- CA
- Canada
- Prior art keywords
- photoconductive
- composition according
- photoconductive composition
- aqueous
- group
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
- G03G5/02—Charge-receiving layers
- G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
- G03G5/09—Sensitisors or activators, e.g. dyestuffs
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
- G03G5/02—Charge-receiving layers
- G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
- G03G5/08—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic
- G03G5/087—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic and being incorporated in an organic bonding material
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Photoreceptors In Electrophotography (AREA)
- Printing Plates And Materials Therefor (AREA)
Abstract
ABSTRACT OF DISCLOSURE
An aqueous composition-sensitive photoconductive composition useful in the preparation of aqueous composition decoatable electrophotographic elements, such elements and low cost lithographic printing plates prepared from said elements the aqueous composition-sensitive photoconductive composition comprising the admixture of an inorganic photoconductor, an organic photoconductor and an aqueous composition-sensitive resin, and, if desired, to increase exposure speed, a dyestuff photosensitizer.
An aqueous composition-sensitive photoconductive composition useful in the preparation of aqueous composition decoatable electrophotographic elements, such elements and low cost lithographic printing plates prepared from said elements the aqueous composition-sensitive photoconductive composition comprising the admixture of an inorganic photoconductor, an organic photoconductor and an aqueous composition-sensitive resin, and, if desired, to increase exposure speed, a dyestuff photosensitizer.
Description
This invention relates to lithographie printing plates.
~ore partieularly, it rela-tes to an aqueous eomposition-sensitive,;
photoconductive insulating eomposition use~ul in the preparation of electrophotograp~ic elements, to such elements, to a proeess for preparing lithographic printing plates -From sueh eleetro-photographic elements and to the lithographic printing plates prepared by sueh a process.
Electrophotographic reproduction is based on the ability of some normally insulating materials, whose surfaces have been electriccllly charged, to selectively conduct electrie eharge upon image~vise irradiation whereb~ an electrostatic latent image is formed upon such a ma-terial. I.e., the charge is conducted away -from the surFaee and thro`ugh those portions of the insul~ting materials which have been exposed to the radiation while the areas of the surFaee whieh have not been irradiated retain their original charges. The electrostatic la-tent image is an invisible electrostatic charge pattern generated in a usual exposure pro-eedure, e.g., by lens-projected imaging or contaet-printing methods, wherein the charge clensity at the various areas of the surfaee is a funetion of the intensity of irradiation at said areas during exposure. The thus formecl laten-t image may be developed (i.e., made visible~ by treatment with a po-vder (whieh !
may or may not be eolorecl and/or mixed with a binding resin) whieh is attracted to the non-irradiatecl surface areas whieh have retainecl their ellar~es thereby providing a sharp eontrast be-t~veen the irradiated (non-image) and non-irradiated (image) areas. The developillK agent is chosen so that a:Fter -Fixation i-t is resistant to -the subsequent]y applied _~ous composition and prevents attacl; by said so]ution on the unclerlying photoconductive layer.
The visible image is then fi~ed by causing it -tc~ become permanently
~ore partieularly, it rela-tes to an aqueous eomposition-sensitive,;
photoconductive insulating eomposition use~ul in the preparation of electrophotograp~ic elements, to such elements, to a proeess for preparing lithographic printing plates -From sueh eleetro-photographic elements and to the lithographic printing plates prepared by sueh a process.
Electrophotographic reproduction is based on the ability of some normally insulating materials, whose surfaces have been electriccllly charged, to selectively conduct electrie eharge upon image~vise irradiation whereb~ an electrostatic latent image is formed upon such a ma-terial. I.e., the charge is conducted away -from the surFaee and thro`ugh those portions of the insul~ting materials which have been exposed to the radiation while the areas of the surFaee whieh have not been irradiated retain their original charges. The electrostatic la-tent image is an invisible electrostatic charge pattern generated in a usual exposure pro-eedure, e.g., by lens-projected imaging or contaet-printing methods, wherein the charge clensity at the various areas of the surfaee is a funetion of the intensity of irradiation at said areas during exposure. The thus formecl laten-t image may be developed (i.e., made visible~ by treatment with a po-vder (whieh !
may or may not be eolorecl and/or mixed with a binding resin) whieh is attracted to the non-irradiatecl surface areas whieh have retainecl their ellar~es thereby providing a sharp eontrast be-t~veen the irradiated (non-image) and non-irradiated (image) areas. The developillK agent is chosen so that a:Fter -Fixation i-t is resistant to -the subsequent]y applied _~ous composition and prevents attacl; by said so]ution on the unclerlying photoconductive layer.
The visible image is then fi~ed by causing it -tc~ become permanently
-2~
..
attached to a support on which the image is desired. The support may be the original support to which the composi-tion was applied before exposure or a material to which the ima~e was transferred after development and is chosen in accordance with -the desired end use. ~or instance,i~ the final product is to be a lithographic prin-ting plate then the supporting material is a lithographically ¦
suitable supporting material to which the photoconductive compos- ¦
ition is applied and the developed image is fixed directly there- ¦
upon. In tha-t case the exposed areas are removed (decoated) from the plate after the image has been fixed thereon, by means o~ de coating compositions, i.e., aqueous compositions which attack and either dissolve or disperse the exposed photoconductive composi-tion so that it no longer adheres -to the support material.
The electrostatic latent image is formed on the surface of an insulating photoconductive layer carried on a conductive support.
For example, the free surface of the photoconductive layer is uniformly charged, in the dark, e.g., by application of a corona discharge, and most of the charge is maintained on said surface, due to the insulating character of the layer, in the absence of irradiation. Upon imagewise exposure, however, the conductivity of the layer is greatly increased in the irradiated areas in pro- I
~portion to the intensity of irradiation. ThusJ -the surface charge ' in such areas is permitted to "leak" o-ff while the charge in the irradiated areas is not af~ected. This pattern of charged and un-¦
charged surface areas is the aforementioned electrostatic latent image.
Electrophotographic materials and processes are of great importance in many areas of the graphic arts industry including the preparation of lithographic prin-ting plates, where they have been found to be preferable to other conventional methods which require additional process steps of preparing a mask or trans-parency from the original image prior to the exposure step. This .3_ requirement hasl inter alia, the dîsadvantage of using a ~ilm ~or the transparency wnich is expensive (especially i~ the ~ilm uses a silver halide coating) and requiring additional equipment for preparing the transparencies. In -the electrographic processes the above step is not required as the image is formecl on the printing plate directly from the original resulting in consider-able savings in money and time. This increased interest has created a need for suitable materials meeting stringent require-ments regarding, e.g., spectral range of use (i.e., range of 'i radiation waveleng-ths within which material is photoconductive), simplicity of handling, and reliability. In the past such materials have included elemental and inorganic substances such as, selenium, sulfur, zinc oxide, and tellurium and organic sub-stances such as, anthracene and anthraquinone.
The above materials, however, suffer -Erom a number o-f dis-advantages, e.g., in the areas of spectral range of use, ease of handling, light sensitivi-ty and stability.
The above disadvantages have been somewhat obviated by com-positions comprising the substituted oxadiazoles described in U.S. Patent No. 3,ti89,447 or the substituted oxazoles described ~in ~.S. Patent No. 3, 257,203 which may also comprise water insoluble resins, as well as photosensitizers to increase their sensitivity to the visible areas of the spectrum.
However, said compositions su~-fer the disadvantages o-E poor resolution and sensitivity to the "pre-exposure effect" and high material costs.
"Sensitivity to the pre-exposure efEect" reEers to that property o:E some insulating photoconductive materials whereby their capacity to be charged, as vell as their photoconductivity upon irradiation is temporarily decreased upon exposure to radiation, prior to the electrostatic charging. These decreased capacities return to their normal values after the elements have been stored in the dark for a period o~ time. The need for such "dark storage" is disadvantageous either ~vith respect to an in-crease in "down-time" or by requiring an e~cess O:e inventory.
Additionally, the elements comprising the above photoconduc- `
tive compositions can only be decoated using organic solvents.
At present, when the environmental impact of all industrial processes and materials is being critically scrutinized, that factor can be an extreme limitation on the use of such compositionq and provides an incentive for greater research efforts to produc.e elements which can be decoated by means of aqueous compositions.
The instant invention overcomes the aforementioned disadvan-tages by providing a low cost co!nposition which has good spectral sensitivity, good speed, good resolution, is not subject to the pre-exposure effect, and is decoatable, by aqueous compositions.
It is an object of this invention to provide a photocon-ductive insulating composition of good spectral sensitivity, good speed and good r~solution which is soluble or dispersible in aqueous ' compositions.
It is a further object of the invention to provide an electro--photographic element of good spectral sensitivity, good speed, good resol.ution and which after imagewise exposure and fixing may,, be decoated by means of aqueous compositions.
Ihe instant invention also provides a low~cost :lithographic pri.nting plate of good resolution. e .
5_ In accordance with the invention it has now been found that a photoconductive composition of good spectral sensitivity, good speed, good resolution and solubility or dispersibility in aqueous compositions may be prepared by admixing an inorganic photoconductor, a photoconductive organic pigment and at least one insulating resin which is soluble or dispersible in aqueous compositions.
Thus in accordance with this invention there is provided a photoconductive composition~ which is dispersible in aqueous compositions, consisting essentially of an admixture of l. at least one inorganic photoconductor selected from the group consisting of ZnO and TiO2, 11. at least one photoconductive anthraquinone pig-ment, and II~. at least one insulating resin soluble ordispersiblein an aqueous composition.
Inorganic p'notoconductors useful in connection with the invention are any of those known in the art including zinc oxide, titanium dioxide, and the like. A preferred inor-ganic photoconductor is zinc oxide.
The organic photoconductive pigments which may be used according to the invention are known in the art and include anthraquinone class pigments, preferably C.I. Pigment Red ~5 168 (e.g., Monolite TM Red 2Y, I.C.I. Co.~ and C.I.
Pigment Orange 43 (e.g., Indofast TM , Hermon Chemical Co., Hostaperm TM Orange GR, ~oechst Co.) wherein C.I.
indicates "Color Index".
The aqueous composition-sensitive (defined as being either soluble or dispersible in the aqueous composition) resins useful in accordance with the invention are known in the art and include phenol-formaldehyde resins, phenoxy resins, epoxy resins and homo- and co-polymers comprising residues of vinyl alcohol" (which exists only in polymers), hydroxyalkyl acrylates or methacrylates, vinyl acetate, acrylic monomers, N-vinylpyrrolidone-2, vinyl-sulfonic acid, styrenesulfonic acid, acxylamide and its deriva- ¦
tives, maleic anhydride, vinyl e-thers, and the like. Preferred resins are phenoxy resins (e.g., Bakelite phenoxy resin PKH~I, Union Carbide Corp.) and poly(vinyl acetate3 homo- or co-polymers.
The decoating aqueous compositions may be any of -those known to the art for decoating aqueous composition-sensitive resins, preferably aqueous alkaline solutions of pH of greater than 10.
Use of the above compositions is however, limited due to their relatively slow speed. It has now been found, in accordance with another embodiment of the instant invention, that the speed of the above compositions may be increased by addition of dyestuff photosensitizers. Photosensi-tizers which may be used in this in-vention include triarylmethane dyes, such as, ~lethyl Violet;
xanthene dyes such as the rhodamines (e.g., Rhodamine Bj and phthaleins (e.g., Rose Bengal); and the like and mixtures thereof.
A preferred photosensitizer is Rose Bengal.
In a preferred embodiment the photoconductive composition comprises about 3 to about 25~o ~t. of the inorganic photoconductor, amounts of organic photoconductive pigment in the range of about 4 to about 30% wt. and about 20 to about 80% wt. of the aqueous composition-sensitive resin, all o-f the percentages being based on~
the weight of the dried coating.
In a most preferred embodiment the composition -further com-prises about 0.5 to about 5% wt. of dyestuff photosensitizers baseld on the total weight of the dried coating. I
In addition, if desired, the photoconductive composition may I
comprise other additives selected from "other" resins, i.e., resins which are not aqueous composition-sensitive, reactive diluents which are converted to aqueous composition-sensitive resins or "other"
resins upon irradiation, plasticizers, fillers, colorants, -therm-ally and/or photolytically activated polymerization initiators, thermal polymerization inhibitors, and the like and mix-tures thereof.
i _7_ , .', . I
, Other resins useful in connection with the invention may be i illustrated by polystyrene, ABS terpolymers, ethylene-propylene rubbers, and the like.
The reactive diluents may be any oE those known in the art, such as, vinyl ace-tate, styrene, alkyl acrylates and metha- i cyrlates, maleic anhydride, and the like.
According to the invention there is also provided an electro-photographic element comprising an electrically conduc-tive support having adherent to at least one surface thereof any of the photo-conductive compositions of the invention as described above.
The electrically conductive support may comprise any of thosesupports known in the art including metal sheets or foils, glass plates, paper sheets or webs or plastic sheets or webs especially those made of electrically conductive resins. The supports, dependent upon the intended end use of the elements, may be opaque, translucent or transparent. If an absorbent support, such as paper, is ued it is desirable that it be pretreated to prevent absorption of the coating solution The pretreatment may be accomplished by, e.g., adsorption of methyl cellulose or poly (vinyl alcohol) from aqueous solutions or polyamides from aqueous alcoholic solutions.
The photoconductive compositions may be applied to the support by any means kno~vn to the art, such as, spray, meniscus, wire wound rod reverse coating, gravure coating, whirl coating from solutions in appropriate solvents or by melt coating of the undissolved photoconductive compositions.
The presen-t invention also provides a method for preparing lithographic printing plates which comprises the steps of, I. electrostatically char~ing the free surface of the photoconductive layers of any of the above elements, prepared according to the invention, ~vherein the conductive support comprises a lithographically suitable ma-terial;
.f I --8~
,, , "
II. image-wise exposing the charged surface to radiation, whereby the charge is dischar~ed in the exposed areas in proportion to the intensity of the radiation, to provide an electrostatic latent image;
III developing said laten~ image to provide a visible image;
IV. fixing said visible image, and I V. removing the exposed photoconductive composition by treatment with a suitable aqueous composition to produce the desired printing plate.
If desired, stages I to IV may be repeated several times, before going to to step V, using different masks in order to superimpose several images upon each other in the final plate.
IYhile the coatings are, in tllemselves, non-r~diation-sen~itiv,e application of a positive or negative electrostatic charge thereto~, e.g., by means of a corona discharge, renders them radiation-sensitive.
The electrostatic latent image is formed on the charged element by imagewise irradiation thereof. The racliation may be , selected ~rom the whole electromagnetic spectrum including1 visible light~ UV or IR radiation and electron beam. Preferred radiation is in the UV and visible light areas of the spectrum.
Development of the latent electrostatic image may be accomplished by any neans known in the art including treatment of the imagewise exposed eoement with liquid or dry toners such as, dye filled resins and the carbon black or colored resin described in U.S. Patent No. 3,139,447.
The developed (visible) image is then made permanent, ~i.e., ~fixed) e.g., by heating in -the presence or absence of solvent vapors, or by treatment with steam and/or pressure.
The thus fixed image element is then convertecl to the desired lithographic printing plate by treatment with an appropriate, ~aqueous composition, preferably an aqueous alkali solution prefer-ably o-f a pll of greater of 10, to remove the exposed aqueous r _9.
composition soluble or dispersible photoconductive composition.
i If desired, the aqueous composi-tion may also comprise organic solvents to aid in wetting the resinous components of the photo~
conductive composition whereby removal of the exposed composition~
from the support is facilitated.
The ~ollowing examples are illustrative of the invention and methods for its accomplishment.
Example 1 ~t A mixture comprising 10.0 gms of Monolite TM Red 2Y, 8.0 gms of ZnO, 0.1 gms of Rose Bengal, 50 ml. of methyl Cellosolve T~lt~lC) and ~00 ml methyl ethyl ketone (MEK) ~vas ground in a ball mill I -~' tusing Borundum T~ balls) for 16 hours. To the above mixture was then added a solution comprising 40.0 gms of Resyn ~ 28 2930 ta carboxylated vinyl acetate terpolymer manu~actured by National Starch and Chemical Corp., Bridge-vater, N.J.) 50 ml of ~IC and 100 ml MEK. The resultant mixture ~Yas then milled an additional
..
attached to a support on which the image is desired. The support may be the original support to which the composi-tion was applied before exposure or a material to which the ima~e was transferred after development and is chosen in accordance with -the desired end use. ~or instance,i~ the final product is to be a lithographic prin-ting plate then the supporting material is a lithographically ¦
suitable supporting material to which the photoconductive compos- ¦
ition is applied and the developed image is fixed directly there- ¦
upon. In tha-t case the exposed areas are removed (decoated) from the plate after the image has been fixed thereon, by means o~ de coating compositions, i.e., aqueous compositions which attack and either dissolve or disperse the exposed photoconductive composi-tion so that it no longer adheres -to the support material.
The electrostatic latent image is formed on the surface of an insulating photoconductive layer carried on a conductive support.
For example, the free surface of the photoconductive layer is uniformly charged, in the dark, e.g., by application of a corona discharge, and most of the charge is maintained on said surface, due to the insulating character of the layer, in the absence of irradiation. Upon imagewise exposure, however, the conductivity of the layer is greatly increased in the irradiated areas in pro- I
~portion to the intensity of irradiation. ThusJ -the surface charge ' in such areas is permitted to "leak" o-ff while the charge in the irradiated areas is not af~ected. This pattern of charged and un-¦
charged surface areas is the aforementioned electrostatic latent image.
Electrophotographic materials and processes are of great importance in many areas of the graphic arts industry including the preparation of lithographic prin-ting plates, where they have been found to be preferable to other conventional methods which require additional process steps of preparing a mask or trans-parency from the original image prior to the exposure step. This .3_ requirement hasl inter alia, the dîsadvantage of using a ~ilm ~or the transparency wnich is expensive (especially i~ the ~ilm uses a silver halide coating) and requiring additional equipment for preparing the transparencies. In -the electrographic processes the above step is not required as the image is formecl on the printing plate directly from the original resulting in consider-able savings in money and time. This increased interest has created a need for suitable materials meeting stringent require-ments regarding, e.g., spectral range of use (i.e., range of 'i radiation waveleng-ths within which material is photoconductive), simplicity of handling, and reliability. In the past such materials have included elemental and inorganic substances such as, selenium, sulfur, zinc oxide, and tellurium and organic sub-stances such as, anthracene and anthraquinone.
The above materials, however, suffer -Erom a number o-f dis-advantages, e.g., in the areas of spectral range of use, ease of handling, light sensitivi-ty and stability.
The above disadvantages have been somewhat obviated by com-positions comprising the substituted oxadiazoles described in U.S. Patent No. 3,ti89,447 or the substituted oxazoles described ~in ~.S. Patent No. 3, 257,203 which may also comprise water insoluble resins, as well as photosensitizers to increase their sensitivity to the visible areas of the spectrum.
However, said compositions su~-fer the disadvantages o-E poor resolution and sensitivity to the "pre-exposure effect" and high material costs.
"Sensitivity to the pre-exposure efEect" reEers to that property o:E some insulating photoconductive materials whereby their capacity to be charged, as vell as their photoconductivity upon irradiation is temporarily decreased upon exposure to radiation, prior to the electrostatic charging. These decreased capacities return to their normal values after the elements have been stored in the dark for a period o~ time. The need for such "dark storage" is disadvantageous either ~vith respect to an in-crease in "down-time" or by requiring an e~cess O:e inventory.
Additionally, the elements comprising the above photoconduc- `
tive compositions can only be decoated using organic solvents.
At present, when the environmental impact of all industrial processes and materials is being critically scrutinized, that factor can be an extreme limitation on the use of such compositionq and provides an incentive for greater research efforts to produc.e elements which can be decoated by means of aqueous compositions.
The instant invention overcomes the aforementioned disadvan-tages by providing a low cost co!nposition which has good spectral sensitivity, good speed, good resolution, is not subject to the pre-exposure effect, and is decoatable, by aqueous compositions.
It is an object of this invention to provide a photocon-ductive insulating composition of good spectral sensitivity, good speed and good r~solution which is soluble or dispersible in aqueous ' compositions.
It is a further object of the invention to provide an electro--photographic element of good spectral sensitivity, good speed, good resol.ution and which after imagewise exposure and fixing may,, be decoated by means of aqueous compositions.
Ihe instant invention also provides a low~cost :lithographic pri.nting plate of good resolution. e .
5_ In accordance with the invention it has now been found that a photoconductive composition of good spectral sensitivity, good speed, good resolution and solubility or dispersibility in aqueous compositions may be prepared by admixing an inorganic photoconductor, a photoconductive organic pigment and at least one insulating resin which is soluble or dispersible in aqueous compositions.
Thus in accordance with this invention there is provided a photoconductive composition~ which is dispersible in aqueous compositions, consisting essentially of an admixture of l. at least one inorganic photoconductor selected from the group consisting of ZnO and TiO2, 11. at least one photoconductive anthraquinone pig-ment, and II~. at least one insulating resin soluble ordispersiblein an aqueous composition.
Inorganic p'notoconductors useful in connection with the invention are any of those known in the art including zinc oxide, titanium dioxide, and the like. A preferred inor-ganic photoconductor is zinc oxide.
The organic photoconductive pigments which may be used according to the invention are known in the art and include anthraquinone class pigments, preferably C.I. Pigment Red ~5 168 (e.g., Monolite TM Red 2Y, I.C.I. Co.~ and C.I.
Pigment Orange 43 (e.g., Indofast TM , Hermon Chemical Co., Hostaperm TM Orange GR, ~oechst Co.) wherein C.I.
indicates "Color Index".
The aqueous composition-sensitive (defined as being either soluble or dispersible in the aqueous composition) resins useful in accordance with the invention are known in the art and include phenol-formaldehyde resins, phenoxy resins, epoxy resins and homo- and co-polymers comprising residues of vinyl alcohol" (which exists only in polymers), hydroxyalkyl acrylates or methacrylates, vinyl acetate, acrylic monomers, N-vinylpyrrolidone-2, vinyl-sulfonic acid, styrenesulfonic acid, acxylamide and its deriva- ¦
tives, maleic anhydride, vinyl e-thers, and the like. Preferred resins are phenoxy resins (e.g., Bakelite phenoxy resin PKH~I, Union Carbide Corp.) and poly(vinyl acetate3 homo- or co-polymers.
The decoating aqueous compositions may be any of -those known to the art for decoating aqueous composition-sensitive resins, preferably aqueous alkaline solutions of pH of greater than 10.
Use of the above compositions is however, limited due to their relatively slow speed. It has now been found, in accordance with another embodiment of the instant invention, that the speed of the above compositions may be increased by addition of dyestuff photosensitizers. Photosensi-tizers which may be used in this in-vention include triarylmethane dyes, such as, ~lethyl Violet;
xanthene dyes such as the rhodamines (e.g., Rhodamine Bj and phthaleins (e.g., Rose Bengal); and the like and mixtures thereof.
A preferred photosensitizer is Rose Bengal.
In a preferred embodiment the photoconductive composition comprises about 3 to about 25~o ~t. of the inorganic photoconductor, amounts of organic photoconductive pigment in the range of about 4 to about 30% wt. and about 20 to about 80% wt. of the aqueous composition-sensitive resin, all o-f the percentages being based on~
the weight of the dried coating.
In a most preferred embodiment the composition -further com-prises about 0.5 to about 5% wt. of dyestuff photosensitizers baseld on the total weight of the dried coating. I
In addition, if desired, the photoconductive composition may I
comprise other additives selected from "other" resins, i.e., resins which are not aqueous composition-sensitive, reactive diluents which are converted to aqueous composition-sensitive resins or "other"
resins upon irradiation, plasticizers, fillers, colorants, -therm-ally and/or photolytically activated polymerization initiators, thermal polymerization inhibitors, and the like and mix-tures thereof.
i _7_ , .', . I
, Other resins useful in connection with the invention may be i illustrated by polystyrene, ABS terpolymers, ethylene-propylene rubbers, and the like.
The reactive diluents may be any oE those known in the art, such as, vinyl ace-tate, styrene, alkyl acrylates and metha- i cyrlates, maleic anhydride, and the like.
According to the invention there is also provided an electro-photographic element comprising an electrically conduc-tive support having adherent to at least one surface thereof any of the photo-conductive compositions of the invention as described above.
The electrically conductive support may comprise any of thosesupports known in the art including metal sheets or foils, glass plates, paper sheets or webs or plastic sheets or webs especially those made of electrically conductive resins. The supports, dependent upon the intended end use of the elements, may be opaque, translucent or transparent. If an absorbent support, such as paper, is ued it is desirable that it be pretreated to prevent absorption of the coating solution The pretreatment may be accomplished by, e.g., adsorption of methyl cellulose or poly (vinyl alcohol) from aqueous solutions or polyamides from aqueous alcoholic solutions.
The photoconductive compositions may be applied to the support by any means kno~vn to the art, such as, spray, meniscus, wire wound rod reverse coating, gravure coating, whirl coating from solutions in appropriate solvents or by melt coating of the undissolved photoconductive compositions.
The presen-t invention also provides a method for preparing lithographic printing plates which comprises the steps of, I. electrostatically char~ing the free surface of the photoconductive layers of any of the above elements, prepared according to the invention, ~vherein the conductive support comprises a lithographically suitable ma-terial;
.f I --8~
,, , "
II. image-wise exposing the charged surface to radiation, whereby the charge is dischar~ed in the exposed areas in proportion to the intensity of the radiation, to provide an electrostatic latent image;
III developing said laten~ image to provide a visible image;
IV. fixing said visible image, and I V. removing the exposed photoconductive composition by treatment with a suitable aqueous composition to produce the desired printing plate.
If desired, stages I to IV may be repeated several times, before going to to step V, using different masks in order to superimpose several images upon each other in the final plate.
IYhile the coatings are, in tllemselves, non-r~diation-sen~itiv,e application of a positive or negative electrostatic charge thereto~, e.g., by means of a corona discharge, renders them radiation-sensitive.
The electrostatic latent image is formed on the charged element by imagewise irradiation thereof. The racliation may be , selected ~rom the whole electromagnetic spectrum including1 visible light~ UV or IR radiation and electron beam. Preferred radiation is in the UV and visible light areas of the spectrum.
Development of the latent electrostatic image may be accomplished by any neans known in the art including treatment of the imagewise exposed eoement with liquid or dry toners such as, dye filled resins and the carbon black or colored resin described in U.S. Patent No. 3,139,447.
The developed (visible) image is then made permanent, ~i.e., ~fixed) e.g., by heating in -the presence or absence of solvent vapors, or by treatment with steam and/or pressure.
The thus fixed image element is then convertecl to the desired lithographic printing plate by treatment with an appropriate, ~aqueous composition, preferably an aqueous alkali solution prefer-ably o-f a pll of greater of 10, to remove the exposed aqueous r _9.
composition soluble or dispersible photoconductive composition.
i If desired, the aqueous composi-tion may also comprise organic solvents to aid in wetting the resinous components of the photo~
conductive composition whereby removal of the exposed composition~
from the support is facilitated.
The ~ollowing examples are illustrative of the invention and methods for its accomplishment.
Example 1 ~t A mixture comprising 10.0 gms of Monolite TM Red 2Y, 8.0 gms of ZnO, 0.1 gms of Rose Bengal, 50 ml. of methyl Cellosolve T~lt~lC) and ~00 ml methyl ethyl ketone (MEK) ~vas ground in a ball mill I -~' tusing Borundum T~ balls) for 16 hours. To the above mixture was then added a solution comprising 40.0 gms of Resyn ~ 28 2930 ta carboxylated vinyl acetate terpolymer manu~actured by National Starch and Chemical Corp., Bridge-vater, N.J.) 50 ml of ~IC and 100 ml MEK. The resultant mixture ~Yas then milled an additional
3 hours.
The above mixture was applied by means o~ ~18 wire wound , rod to a 14 1/2 in. by 22 inch, 12 gauge sheet of aluminum which had first been pumice grained and anodized. The resultant elemen~
was then dried using a hot air blower followed by heating at 100~
for 1/2 hour to yield the desired electrophotographic element.
Il The free insulating surface of the above element was then ! electrostatically charged by means of a corona discharge, image--wise exposed to a Visible/Argon Laser (Muirhead,Inc.) at 80 amps j Laser power,toned and ~ixed by heating. The-resultant plate was then decoated, to remove exposed ~non-image) portions of the coating,by means of an aqueous alkaline decoating solution. The decoated plate was t~len gu~ned by conventional means and used on an ATF Chief TM press to produce 121,000 acceptable impressions. I
~t ~ ,:
~ o--xa~
Example 1 was repea-ted except that 5.0 gms of Re~ynTM28-2930, were replaced by 5.0 gms of Bakelite TM phenoxy resin PKH~, -the ~onolite Red was replaced by 10.0 gms of Hostaperm TM Orange GR
and only 4.0 gms of ZnO were used. Similar results were ob~ained.
The above mixture was applied by means o~ ~18 wire wound , rod to a 14 1/2 in. by 22 inch, 12 gauge sheet of aluminum which had first been pumice grained and anodized. The resultant elemen~
was then dried using a hot air blower followed by heating at 100~
for 1/2 hour to yield the desired electrophotographic element.
Il The free insulating surface of the above element was then ! electrostatically charged by means of a corona discharge, image--wise exposed to a Visible/Argon Laser (Muirhead,Inc.) at 80 amps j Laser power,toned and ~ixed by heating. The-resultant plate was then decoated, to remove exposed ~non-image) portions of the coating,by means of an aqueous alkaline decoating solution. The decoated plate was t~len gu~ned by conventional means and used on an ATF Chief TM press to produce 121,000 acceptable impressions. I
~t ~ ,:
~ o--xa~
Example 1 was repea-ted except that 5.0 gms of Re~ynTM28-2930, were replaced by 5.0 gms of Bakelite TM phenoxy resin PKH~, -the ~onolite Red was replaced by 10.0 gms of Hostaperm TM Orange GR
and only 4.0 gms of ZnO were used. Similar results were ob~ained.
Claims (13)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A photoconductive composition, which is dispersible in aqueous compositions, consisting essentially of an admixture of
1. at least one inorganic photoconductor selected from the group consisting of ZnO and TiO2, II. at least one photoconductive anthraquinone pigment, and III. at least one insulating resin soluble or dispersible in an aqueous composition.
2. The photoconductive composition according to claim 1 further containing at least one dyestuff sensitizer.
3. The photoconductive composition according to claim 2 wherein said dyestuff sensitizer is selected from the group consist-ing of triarylmethane and xanthene dyes.
4. The photoconductive composition according to claim 3 wherein said dyestuff sensitizer is Rose Bengal.
5. The photoconductive composition according to claim 1 wherein said photoconductor is ZnO.
6. The photoconductive composition according to claim 1 wherein said pigment is selected from the group consisting of C.l Pigment Red 168, and C.I. Pigment Orange 43.
7. The photoconductive composition according to any one of claims 1,5 or 6 wherein said resin is selected from the group consisting of phenolformaldehyde resins, phenoxy resins, epoxy resins and homo and co-polymers of vinyl acetate, and acrylic monomers.
8. The photoconductive composition according to claim 1 wherein said inorganic photoconductor is ZnO, and the organic photoconductor is C.I. Pigment Orange 43, and the resin is a carboxyl containing poly (vinyl acetate) copolymer.
9. The photoconductive composition according to claim 2 wherein said inorganic photoconductor is ZnO, and the organic photoconductor is C. I. Pigment Orange 43, the resin is a carboxyl containing poly (vinyl acetate) copolymer and the sensitizer is Rose Bengal.
10. The photoconductive composition according to claim 1 further containing at least one additive selected from the group consisting of colourants, other resins reactive diluents, plasticizers and fillers.
11. The photoconductive compositions according to claim 10 fur-ther containing at least one additive selected from thermally and/or phytolitically activated polymerization initiators, and thermal polymerization initiators.
12. An electrophotographic element comprising a conductive base material having coated upon at least one surface thereof a photoconductive composition, which is soluble or dispersible in aqueous compositions, consisting essentially of as major ingredients:
1. at least one inorganic photoconductor selected from the group consisting of ZnO and TiO2, II. at least one photoconductive anthraquinone pigment, and III. at least one insulating resin soluble or dispersible in an aqueous composition.
1. at least one inorganic photoconductor selected from the group consisting of ZnO and TiO2, II. at least one photoconductive anthraquinone pigment, and III. at least one insulating resin soluble or dispersible in an aqueous composition.
13. The element according to claim 10 wherein said composition further contains at least one dyestuff sensitizer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US28902781A | 1981-08-03 | 1981-08-03 | |
| US289,027 | 1988-12-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1181626A true CA1181626A (en) | 1985-01-29 |
Family
ID=23109703
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000408553A Expired CA1181626A (en) | 1981-08-03 | 1982-07-30 | Aqueous composition-sensitive photoconductive composition containing zn0 or ti0 in2 xx and a photoconductive anthraquinone pigment |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5827151A (en) |
| AU (1) | AU8635882A (en) |
| CA (1) | CA1181626A (en) |
| DE (1) | DE3227475A1 (en) |
| FR (1) | FR2510775B1 (en) |
| GB (1) | GB2103818B (en) |
| IT (1) | IT1149332B (en) |
| NL (1) | NL8202927A (en) |
| ZA (1) | ZA825152B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6046507U (en) * | 1983-09-07 | 1985-04-02 | 三菱レイヨン株式会社 | optical coupler |
| DE3417951A1 (en) * | 1984-05-15 | 1985-11-21 | Hoechst Ag, 6230 Frankfurt | ELECTROPHOTOGRAPHIC RECORDING MATERIAL |
| JPH07110419B2 (en) * | 1986-08-26 | 1995-11-29 | マツダ株式会社 | Overlap welding method |
| JPH0638174B2 (en) * | 1987-03-16 | 1994-05-18 | 三菱製紙株式会社 | Electrophotographic planographic printing plate |
| JP2622753B2 (en) * | 1988-06-27 | 1997-06-18 | 石原産業株式会社 | How to create an offset printing master |
| JPH03146957A (en) * | 1989-11-02 | 1991-06-21 | Iwatsu Electric Co Ltd | Printing plate for electrophotographic engraving |
| WO2011145111A1 (en) * | 2010-05-18 | 2011-11-24 | Secretary, Department Of Information Technology (Dit) | Micro/nano photoconductor |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1117391B (en) * | 1959-03-18 | 1961-11-16 | Kalle Ag | Electrophotographic process for the production of printing forms |
| BE613038A (en) * | 1961-01-25 | |||
| DE2054118A1 (en) * | 1970-11-04 | 1972-05-10 | Hauffe K | Bipolar charge-/discharge-able coating - for xerography with zinc oxide and photoconductive organic pigment in resin |
| DE2322046C3 (en) * | 1973-05-02 | 1979-11-22 | Hoechst Ag, 6000 Frankfurt | Process for the production of printing forms |
| US4076528A (en) * | 1973-05-12 | 1978-02-28 | Xerox Corporation | Xerographic binder plate |
| JPS5840734B2 (en) * | 1975-12-24 | 1983-09-07 | 株式会社リコー | Kodo Denseikan Kotai |
| JPS5845709B2 (en) * | 1976-10-09 | 1983-10-12 | 三菱製紙株式会社 | Electrophotographic paper for lithographic printing with improved base paper |
| JPS6059587B2 (en) * | 1979-03-23 | 1985-12-25 | コニカ株式会社 | electrophotographic photoreceptor |
-
1982
- 1982-07-19 ZA ZA825152A patent/ZA825152B/en unknown
- 1982-07-20 NL NL8202927A patent/NL8202927A/en not_active Application Discontinuation
- 1982-07-22 DE DE19823227475 patent/DE3227475A1/en not_active Ceased
- 1982-07-22 GB GB08221219A patent/GB2103818B/en not_active Expired
- 1982-07-23 AU AU86358/82A patent/AU8635882A/en not_active Abandoned
- 1982-07-30 JP JP57134624A patent/JPS5827151A/en active Pending
- 1982-07-30 IT IT48915/82A patent/IT1149332B/en active
- 1982-07-30 CA CA000408553A patent/CA1181626A/en not_active Expired
- 1982-08-03 FR FR8213566A patent/FR2510775B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5827151A (en) | 1983-02-17 |
| AU8635882A (en) | 1983-02-10 |
| GB2103818B (en) | 1985-03-20 |
| ZA825152B (en) | 1983-07-27 |
| IT8248915A0 (en) | 1982-07-30 |
| FR2510775A1 (en) | 1983-02-04 |
| GB2103818A (en) | 1983-02-23 |
| DE3227475A1 (en) | 1983-02-17 |
| NL8202927A (en) | 1983-03-01 |
| FR2510775B1 (en) | 1989-09-22 |
| IT1149332B (en) | 1986-12-03 |
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