CA1075300A - Offset printing - Google Patents
Offset printingInfo
- Publication number
- CA1075300A CA1075300A CA234,743A CA234743A CA1075300A CA 1075300 A CA1075300 A CA 1075300A CA 234743 A CA234743 A CA 234743A CA 1075300 A CA1075300 A CA 1075300A
- Authority
- CA
- Canada
- Prior art keywords
- printing
- lithographic printing
- oleophilic
- marking particles
- areas
- 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.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G13/00—Electrographic processes using a charge pattern
- G03G13/26—Electrographic processes using a charge pattern for the production of printing plates for non-xerographic printing processes
- G03G13/28—Planographic printing plates
- G03G13/283—Planographic printing plates obtained by a process including the transfer of a tonered image, i.e. indirect process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
- B41N3/00—Preparing for use and conserving printing surfaces
- B41N3/006—Cleaning, washing, rinsing or reclaiming of printing formes other than intaglio formes
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Printing Methods (AREA)
- Photoreceptors In Electrophotography (AREA)
- Manufacture Or Reproduction Of Printing Formes (AREA)
- Developing Agents For Electrophotography (AREA)
- Printing Plates And Materials Therefor (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method of preparing a reusable lithographic printing surface comprises produced an electrostatic latent image on the surface of a dielectric recording member and developing the image by the attraction thereto of oleophilic electroscopic marking particles and then transferring the developed image to metal surface, and fusing the developer to the hydrophilic metal surface the olephilic electroscopic marking particles being characterised by the inclusion therein of resinous material selected to be resistive to components of the lithographic printing ink which is to be used in conjunction with such lithographic printing surface, and further selected to be soluble in a solvent selected from the group of ketones, alcohols and chlorinated hydrocarbons.
A method of preparing a reusable lithographic printing surface comprises produced an electrostatic latent image on the surface of a dielectric recording member and developing the image by the attraction thereto of oleophilic electroscopic marking particles and then transferring the developed image to metal surface, and fusing the developer to the hydrophilic metal surface the olephilic electroscopic marking particles being characterised by the inclusion therein of resinous material selected to be resistive to components of the lithographic printing ink which is to be used in conjunction with such lithographic printing surface, and further selected to be soluble in a solvent selected from the group of ketones, alcohols and chlorinated hydrocarbons.
Description
~L~7~3~
BACKGROUND OF TIIE INVENTION
Offset lithography is a well known printing process in which the printing surface is substantially planographic, and contains on its printing surface printing areas which 5. are ink accepting, and non-printing areas which are water accep-ting. The printing member is normally a relatively thin metallic sheet having on one surface an ink accepting printing deposit, the printing member normally being prepared away from the printing press by the application of 10. an ink accepting printing deposit to a water accepting surface.
The prepared pxinting member is normally wrapped around-a cylinder, hereinaE-ter referred to as a printing cylinder, and clamped thereto. Roller systems are located adjacent to the printing cylinder to apply water or water ~olutions 150 to the printing surface to wet the non-printing or background areas prior to the application of hydrophobic ink, applied by a urther set of rollers. The water or water solution contained on the non-printing areas of the pxinting surface prevents adherence of the hydrophobic ink 20. thereto, the ink thus adhering to the printing areas only.
In offset lithography the pxinting ink transferred to the printing areas cf the printing surface is transferred subsequently to a blanket of resilient material, such as synthetic rubber or the like, contained as a surface layer 25. on a furthel^ cylinder which rotates in contact with the printing cylinder surace. A further cylinder, known as an impression cylinder, rotates in contact with the blanket cylinder/ and the paper to be printed is fed into and through .
. ' ~
~753~6~
the nip between the blanket cylinder and the impression cylinder to cause transfer of the printing ink deposit from the blanket to the paper. Lithographic printing presses may be web fed or sheet fed, and may contain a 5. multiplieity of printing stations to produce multicolor reproductions and be capable of printing one or both sides of the paper.
As previously stated, offset printing plates are prepared away from the printing press, usually by contact 10. exposure of a light sensitive resist on the surface of the printing plate, which resist is subsequently etehed to differentiate hetween printing and non-printing areas.
Metal printing plates may be of the type commonly known as bi-metal or tri-metal plates eontaining on their printing 15. surfaees suecessive layers of water aeeepting and ink aceepting metals. In these instances the etch resist is used to eontrol the etehing of the top layer of metal, whereby for instance a printing plate may be produced eontaining printing areas consisting of metallie copper 20. and non-printing areas eonsisting of metallie ehromium.
Other wa~er aecepting metals sueh as grained zine and grained aluminium are also used for lithographic printing plates. In these instances the ink aeeepting printing areas usually eonsist of hardened photoresist.
25. Prior art offset printing presses are eonstrueted to allow fitting of printing plates as previously dese~ibed.
Thus the plate eylinder includes elamping means whieh normally allow the plate to be stretehed and elamped around ~753~
., the plate cylinder. The end clamps require a gap in the plate cylinder, and such gap extends across the full printing width of the plate cylinderO
Thus prior art offset printing presses are not 5. adaptable to continuous printing, such as is required for wall paper printing or the printing of transfer paper for textile printing~ -Furthermore in prior art offset printing processesthe printing plate is not normally considered to be 10. reusable, and at the conclusion of each printing run it is necessary to remove and discard each printing plate thereon and insert other printing plates for further press runs. This operation involves considerable press down-time and material wastageO
15. The present invention teaches a method and means whereby these deficiencies may be overcome, and in a~dition teaches a method of printing surface preparation which may be carried out on the printing press.
DESCRIPTION OF THE IN-~ENTION
._ _ _ . , .
~0. The present invention relakes to printing surface preparation, and allows the placing of an ink accepting printing deposit on a water accepting surface, which water accepting surface may if desired by a continu~us cylindrical form. Thus the ink accepting printing deposit may form a 250 continuous pattern around the cylindrical surface with no gap or joint line, thereby allowing the continuous printing o~ paper webs or the like.
This invention involves process steps as now followsO
~7~3~ ~
A dielectric recording member is imaged by imposition thereon of a pat-tern corresponding to the information to be printed. Such pattern is in the form of an electrostatic latent image contained on one surface of a 5. reusable or disposable dielectric electrophotographic ox electxostatic recording member. The electrostatic latent image is developed by a-ttraction thereto of electroscopic markin~ particles. The developed image deposit is subsequently transferred to the printing surface using 10. electrostatic transfer methods similar to those of U.S. Pat. No. 3,419,~11, U.S. Pat. Mo. 3,328,193 and U.S. Pat. No. 3r355,288. The transferred image deposit is fixed to the printing surface by the application of heat.
The composition of the electroscopic marking particles 15. used to form the printing deposit on the printing surface is chosen in relation to the composition of the printing ink to be used subsequently, in that the resinous heat fusible or thermoplastic substance contained in such electroscopic marking particles must withstand contact with the offset 20. ink without being degraded for instance by solvation, swelling or chemical reaction with the oleoresinous vehicles and/or dilutents or solvents used for same contained in the offset ink. In addition, in those instances where in accordance with this invention it is required to re-use the 25. printing surface the composition of the electroscopic marking particles used to for~ the printing deposit is also influenced by requirements for printing deposit removal and printing surface reconditioning after completion of the ,3~
printing XUII.
The nature of the printing surface and the desired printing run length also determine the selection of materials for the composition of the electroscopic 5- marking particles.
It will be realised that the dielectric recording member comprises a base mernber having disposed on one surface at least thereof a dielectric layer capable of retaining an electrostatic charge. Such dielectric 10. recording member may comprise a base having on one side I a layer of insulating resin or the like, or altern~.tively . . . ~
such dielectric recording member may comprise a base having on one side thereof a photoconductive layer. The type of dielectric recording member used is dependent on the 15. latent image producing means used, as will be hereinafter described. ~'urther the dielectric recording member may be disposable or reusable as desired.
Printing surfaces in accordance with the present invention may be considered to be reusable. The 20. printing deposit on the printing surface comprises an oleophilic pigmented resin deposit, which pigmented resin deposit is heat fused to the printing surface. Upon completion of the printing run the printing deposit may be removed frorn the printing surface by the application of 25. a suitable solvent for the resin of the printing deposit.
Such solvent m~y be applied by dipping, brushing, spraying or other me~ns as desired, and in addition image deposit - removal may be assisted by the concurrent applica~ion of ~7~3~
friction through a suitable applicator such as a rotating brush or the like. Generally the solvent used to remove the image deposit will also remove printing ink and recondition the printing surface 5~ upon drying for re-imaging, although in some instances further reconditioning treatment may be required, such as rinsing with c~ean solvent of the same cor,lposition as that used to remove the image deposit, or of different composition thereto, followed by further drying of the 10. printing surfaceO
The printing surface in accordance with this invention may be any water accepting metal surface, such as grained or anodized aluminium, grained zinc, chromium, nickel, or stainless steel. The water accepting metal 15. used is dependent largely on printing surface life and reusability requirements. Thus when the printing surface is in the form of a reusable contlnuous cylinder it is advantageous to use chromium or stainless steel or other water accepting relatively-non-corrosive hard material 20. for the printing surface. In those instances in which ; the present invention is used to produce wrap around printing plates suitable for attachment to prior art lithographic printing presses less durable materials such as grained aluminium may be used. Even in these instances 25. limited plate reusability is attainable, such as 5 to 10 reimaging cycles.
In order that the invention may be more readily understood, reference will now be made to specific 53~
examples. However it will be realised that offset llthography is a widely used printing process and a variety of lithographic printing machines are used to print a wide variety of papers using a wide variety of 5. jobbing and special purpose lithographic printing inks.
Thus in the following examples printing deposit toner formulations are disclosed in relation to certain specific inks and printing surfaces. However those skilled in the art will be able to adhpt the teachings herein disclosed 10. for lithographic print:ing purposes not spe~ifically , described wi-thout departing from the spirit of the present - ~ invention. Consequently the examples should be read as illustrative only and not in the limiting sense.
15. A photoconductive recording member was prepared by coating a paper base with a 25 gsm dry weight coating oE
the following composition.
Photoconductive zinc oxide 175 grms Epoxy ester resin, 50% solids 100 grms 20. Toluene 100 grms The components were mixed together and ball milled for 60 hours to a Hegman gauge reading of 7O5~ The epoxy ester resin is a dehydrated castor oil modified epoxy resin, specific gravity 0.9, short oil length, acid 25. value 5-~.
The thus produced photoconductive recording member was charged and exposed using a positive transparency of the material to be printed as a light mask to form an ~37536~
electrostatic latent image thereon. The electrostatic latent image was of negative charge.
A dispersion of electroscopic marking particles was prepared as follows:
5- Pigment C.I. Pigment Red 53 30 grms Retone resin, cyclohexanone formaldehyde type95 grms Ethanol 200 grms The ketone resin was dissolved in the ethanol, and 10. the pigment was then added. The resultant mixture was ball-mixed for 4 hours and subsequently precipitated in water, filtered, drled and crushed.
The crushed powder was dispersed by milling in 1200 grms of isoparaffinic hydrocarbon dispersant.
15.The thus produced dispersion was used to develop the previously produced electrostatic latent image on the I surface of the electrophotographic recording member.
I A grained aluminium offset printing plate was ~ positioned on a grounded base member and the developed -, 20. surface o~ the photoconductive recording member was contacted therewith. The developed image deposit was transferred to the grained aluminium surface using electrostatic transfer technique.
The transferred image deposit was then fixed to the 25. printing plate by heat fusion at a temperature of within the range 110-120C.
The image bearing printing plate was attached to the plate cylinder of a small offset printing press and .
9.' ~7~3~
used to pri.nt 1000 copies of the information thereon on paper using a jobbing balck offset printing ink.
After complet:ion of 'che printing run the printing plate was cleaned by rubbillg with a cloth pad wetted with 5- methyl ethyl ketone, which remo~ed bo-th residual printing nk and the image deposit, leaving the printing plate in a suitable condition for re-use.
In addition to being uneffected by the components of the jobbing black offset printing ink used, the image 10. deposit of this example was also uneffected by the components of an offset printing ink suited to heat transfer calender printing of textiles.
Example 1 was repeated with the exception that the 15. grained aluminium printing plate was replaced with a grained zinc printing plate.
EXA~IPLES 3~and 4 . . _ .
Examples 1 and 2 weJ:e repeated with the exception I that the electrostatic latent image on the electro-20. photographic recording member was developed using a li~uid dispersed toner of the following composi-tion:
`; Resinated phthalocyamine blue pigment such as microlith blue 4GT, by Ciba-Geigy 14 grms 25. Solid epoxy resin, crushed, epoxide eq~iv~lent 870-1000 28 grms Isoparaffinic hydrocarbon dispersant 250 grms These components were ball milled together for 72 hours~
~753~
and diluted for use as a toner in the proportions 20 ml - of concentrate to 1 litre isoparaffinic hydrocarbon dispersant.
In t~is instance the fusing temperature of the image ; 5. deposit was 96-104C. The plate~was cleaned after completion of the printing run by rubbing with a cloth pad wetted with methylene chloride.
In addition to being uneffected by the components of the jobbing black offset-printing ink used, the image 10. deposit of these examples was also uneffected by the components of an offset printing ink suited to heat transfer calender printing of textiles.
E~MPLES 5 - 8 Each of examples 1-4 were repeated using a dye 15. sensitised photoconductive recording member, which was exposed after charging using a fibre optic faceplate cathode ray tube controlled by an input signal corresponding to the information to be reproduced.
-20. Each of examples 1-4 were repeated using a dielectric recording member as the image bearing member. The dielectric recording member comprised a paper base having on one surface thereof a 5 gsm layer of polyvinyl J
butyral resin. The latent image was produced by stylus 25. wri~ing, using writing styli to which 500 volt negative pulses were applied from a control circuitry to produce an electrostatic latent image thereon corresponding to alphanumeric information~
11 .
~753~
Each of examples 1 to 12 were repeated with the exception that the printing plates were in the form of continuous cylinders o~ grained aluminium and grained 5. zinc respectively. In these examples electrostatic image transfer was car~ied out directly on the printing press, the electrostatic transfer means comprising a roller attached to the printing press to form a nip between said roller and the prin-ting cylinder through which nip the 10. developed recording member was passed to ef~ect transfer o the image deposit contained thereon to the printing cylinder. , Examples 3 and 4 were repeated with the exception 15. that the crushed epoxy resin ~as replaced with a crushed epoxy resin, epoxide equivalent 450-525, melting range 64-74C, specific gravity 1.2.
i Examples 3 and 4 were repeated with the exception 20. that the crushed epoxy resin was replaced ~ith a crushed solid epoxy resin, epoxide equivalent 575-700, melting range 80-90~o Examples 1 and 2 were xepeated with the exception 25. that the electrostatic latent image on thç electro-photographic recording mem~er was de~eloped using a liquid dispersed toner of the Eollowing composition:
~L~7~3~
Alcohol sol~ble resin maleic ester, 30 grms - Acid No, 110-125, SG 1.08, melting point 130-140C.
Resinated carbon black, hydrocarbGn 15 yrms 5. dispersible, such as Microlith Black CT, by Ciba-Geigy.
- Isoparaf-finic hydrocarbon250 grms These components wer~ ball,milled together for 72 hours, and diluted for use in the proportions 20 ml of concentrate 10. to 1 litre isoparaffinic hydrocarbon dispersant.
The plate was cleaned after completion of the printiny run by rubbing with a cloth pad wetted with butanol.
Examples 1, 3 and 29 were xepeated with the exception 15. that the grained al~ninium printing plate was replaced with a tri-metal plate, the wacer accepting,surface of which was electroplated chromium.
There has been described an imaging method and means whereby printing deposits can,be produced on offset printing 20. surfaces. The herein described method and means is suited to the formation of printing deposits'on continuous printing surfaces, which has not heretofor been known in relation to offset lithography. In addition the disclosed method and means allows reuse of the prin~ing surface on completion 25. of the printing run.
13.
BACKGROUND OF TIIE INVENTION
Offset lithography is a well known printing process in which the printing surface is substantially planographic, and contains on its printing surface printing areas which 5. are ink accepting, and non-printing areas which are water accep-ting. The printing member is normally a relatively thin metallic sheet having on one surface an ink accepting printing deposit, the printing member normally being prepared away from the printing press by the application of 10. an ink accepting printing deposit to a water accepting surface.
The prepared pxinting member is normally wrapped around-a cylinder, hereinaE-ter referred to as a printing cylinder, and clamped thereto. Roller systems are located adjacent to the printing cylinder to apply water or water ~olutions 150 to the printing surface to wet the non-printing or background areas prior to the application of hydrophobic ink, applied by a urther set of rollers. The water or water solution contained on the non-printing areas of the pxinting surface prevents adherence of the hydrophobic ink 20. thereto, the ink thus adhering to the printing areas only.
In offset lithography the pxinting ink transferred to the printing areas cf the printing surface is transferred subsequently to a blanket of resilient material, such as synthetic rubber or the like, contained as a surface layer 25. on a furthel^ cylinder which rotates in contact with the printing cylinder surace. A further cylinder, known as an impression cylinder, rotates in contact with the blanket cylinder/ and the paper to be printed is fed into and through .
. ' ~
~753~6~
the nip between the blanket cylinder and the impression cylinder to cause transfer of the printing ink deposit from the blanket to the paper. Lithographic printing presses may be web fed or sheet fed, and may contain a 5. multiplieity of printing stations to produce multicolor reproductions and be capable of printing one or both sides of the paper.
As previously stated, offset printing plates are prepared away from the printing press, usually by contact 10. exposure of a light sensitive resist on the surface of the printing plate, which resist is subsequently etehed to differentiate hetween printing and non-printing areas.
Metal printing plates may be of the type commonly known as bi-metal or tri-metal plates eontaining on their printing 15. surfaees suecessive layers of water aeeepting and ink aceepting metals. In these instances the etch resist is used to eontrol the etehing of the top layer of metal, whereby for instance a printing plate may be produced eontaining printing areas consisting of metallie copper 20. and non-printing areas eonsisting of metallie ehromium.
Other wa~er aecepting metals sueh as grained zine and grained aluminium are also used for lithographic printing plates. In these instances the ink aeeepting printing areas usually eonsist of hardened photoresist.
25. Prior art offset printing presses are eonstrueted to allow fitting of printing plates as previously dese~ibed.
Thus the plate eylinder includes elamping means whieh normally allow the plate to be stretehed and elamped around ~753~
., the plate cylinder. The end clamps require a gap in the plate cylinder, and such gap extends across the full printing width of the plate cylinderO
Thus prior art offset printing presses are not 5. adaptable to continuous printing, such as is required for wall paper printing or the printing of transfer paper for textile printing~ -Furthermore in prior art offset printing processesthe printing plate is not normally considered to be 10. reusable, and at the conclusion of each printing run it is necessary to remove and discard each printing plate thereon and insert other printing plates for further press runs. This operation involves considerable press down-time and material wastageO
15. The present invention teaches a method and means whereby these deficiencies may be overcome, and in a~dition teaches a method of printing surface preparation which may be carried out on the printing press.
DESCRIPTION OF THE IN-~ENTION
._ _ _ . , .
~0. The present invention relakes to printing surface preparation, and allows the placing of an ink accepting printing deposit on a water accepting surface, which water accepting surface may if desired by a continu~us cylindrical form. Thus the ink accepting printing deposit may form a 250 continuous pattern around the cylindrical surface with no gap or joint line, thereby allowing the continuous printing o~ paper webs or the like.
This invention involves process steps as now followsO
~7~3~ ~
A dielectric recording member is imaged by imposition thereon of a pat-tern corresponding to the information to be printed. Such pattern is in the form of an electrostatic latent image contained on one surface of a 5. reusable or disposable dielectric electrophotographic ox electxostatic recording member. The electrostatic latent image is developed by a-ttraction thereto of electroscopic markin~ particles. The developed image deposit is subsequently transferred to the printing surface using 10. electrostatic transfer methods similar to those of U.S. Pat. No. 3,419,~11, U.S. Pat. Mo. 3,328,193 and U.S. Pat. No. 3r355,288. The transferred image deposit is fixed to the printing surface by the application of heat.
The composition of the electroscopic marking particles 15. used to form the printing deposit on the printing surface is chosen in relation to the composition of the printing ink to be used subsequently, in that the resinous heat fusible or thermoplastic substance contained in such electroscopic marking particles must withstand contact with the offset 20. ink without being degraded for instance by solvation, swelling or chemical reaction with the oleoresinous vehicles and/or dilutents or solvents used for same contained in the offset ink. In addition, in those instances where in accordance with this invention it is required to re-use the 25. printing surface the composition of the electroscopic marking particles used to for~ the printing deposit is also influenced by requirements for printing deposit removal and printing surface reconditioning after completion of the ,3~
printing XUII.
The nature of the printing surface and the desired printing run length also determine the selection of materials for the composition of the electroscopic 5- marking particles.
It will be realised that the dielectric recording member comprises a base mernber having disposed on one surface at least thereof a dielectric layer capable of retaining an electrostatic charge. Such dielectric 10. recording member may comprise a base having on one side I a layer of insulating resin or the like, or altern~.tively . . . ~
such dielectric recording member may comprise a base having on one side thereof a photoconductive layer. The type of dielectric recording member used is dependent on the 15. latent image producing means used, as will be hereinafter described. ~'urther the dielectric recording member may be disposable or reusable as desired.
Printing surfaces in accordance with the present invention may be considered to be reusable. The 20. printing deposit on the printing surface comprises an oleophilic pigmented resin deposit, which pigmented resin deposit is heat fused to the printing surface. Upon completion of the printing run the printing deposit may be removed frorn the printing surface by the application of 25. a suitable solvent for the resin of the printing deposit.
Such solvent m~y be applied by dipping, brushing, spraying or other me~ns as desired, and in addition image deposit - removal may be assisted by the concurrent applica~ion of ~7~3~
friction through a suitable applicator such as a rotating brush or the like. Generally the solvent used to remove the image deposit will also remove printing ink and recondition the printing surface 5~ upon drying for re-imaging, although in some instances further reconditioning treatment may be required, such as rinsing with c~ean solvent of the same cor,lposition as that used to remove the image deposit, or of different composition thereto, followed by further drying of the 10. printing surfaceO
The printing surface in accordance with this invention may be any water accepting metal surface, such as grained or anodized aluminium, grained zinc, chromium, nickel, or stainless steel. The water accepting metal 15. used is dependent largely on printing surface life and reusability requirements. Thus when the printing surface is in the form of a reusable contlnuous cylinder it is advantageous to use chromium or stainless steel or other water accepting relatively-non-corrosive hard material 20. for the printing surface. In those instances in which ; the present invention is used to produce wrap around printing plates suitable for attachment to prior art lithographic printing presses less durable materials such as grained aluminium may be used. Even in these instances 25. limited plate reusability is attainable, such as 5 to 10 reimaging cycles.
In order that the invention may be more readily understood, reference will now be made to specific 53~
examples. However it will be realised that offset llthography is a widely used printing process and a variety of lithographic printing machines are used to print a wide variety of papers using a wide variety of 5. jobbing and special purpose lithographic printing inks.
Thus in the following examples printing deposit toner formulations are disclosed in relation to certain specific inks and printing surfaces. However those skilled in the art will be able to adhpt the teachings herein disclosed 10. for lithographic print:ing purposes not spe~ifically , described wi-thout departing from the spirit of the present - ~ invention. Consequently the examples should be read as illustrative only and not in the limiting sense.
15. A photoconductive recording member was prepared by coating a paper base with a 25 gsm dry weight coating oE
the following composition.
Photoconductive zinc oxide 175 grms Epoxy ester resin, 50% solids 100 grms 20. Toluene 100 grms The components were mixed together and ball milled for 60 hours to a Hegman gauge reading of 7O5~ The epoxy ester resin is a dehydrated castor oil modified epoxy resin, specific gravity 0.9, short oil length, acid 25. value 5-~.
The thus produced photoconductive recording member was charged and exposed using a positive transparency of the material to be printed as a light mask to form an ~37536~
electrostatic latent image thereon. The electrostatic latent image was of negative charge.
A dispersion of electroscopic marking particles was prepared as follows:
5- Pigment C.I. Pigment Red 53 30 grms Retone resin, cyclohexanone formaldehyde type95 grms Ethanol 200 grms The ketone resin was dissolved in the ethanol, and 10. the pigment was then added. The resultant mixture was ball-mixed for 4 hours and subsequently precipitated in water, filtered, drled and crushed.
The crushed powder was dispersed by milling in 1200 grms of isoparaffinic hydrocarbon dispersant.
15.The thus produced dispersion was used to develop the previously produced electrostatic latent image on the I surface of the electrophotographic recording member.
I A grained aluminium offset printing plate was ~ positioned on a grounded base member and the developed -, 20. surface o~ the photoconductive recording member was contacted therewith. The developed image deposit was transferred to the grained aluminium surface using electrostatic transfer technique.
The transferred image deposit was then fixed to the 25. printing plate by heat fusion at a temperature of within the range 110-120C.
The image bearing printing plate was attached to the plate cylinder of a small offset printing press and .
9.' ~7~3~
used to pri.nt 1000 copies of the information thereon on paper using a jobbing balck offset printing ink.
After complet:ion of 'che printing run the printing plate was cleaned by rubbillg with a cloth pad wetted with 5- methyl ethyl ketone, which remo~ed bo-th residual printing nk and the image deposit, leaving the printing plate in a suitable condition for re-use.
In addition to being uneffected by the components of the jobbing black offset printing ink used, the image 10. deposit of this example was also uneffected by the components of an offset printing ink suited to heat transfer calender printing of textiles.
Example 1 was repeated with the exception that the 15. grained aluminium printing plate was replaced with a grained zinc printing plate.
EXA~IPLES 3~and 4 . . _ .
Examples 1 and 2 weJ:e repeated with the exception I that the electrostatic latent image on the electro-20. photographic recording member was developed using a li~uid dispersed toner of the following composi-tion:
`; Resinated phthalocyamine blue pigment such as microlith blue 4GT, by Ciba-Geigy 14 grms 25. Solid epoxy resin, crushed, epoxide eq~iv~lent 870-1000 28 grms Isoparaffinic hydrocarbon dispersant 250 grms These components were ball milled together for 72 hours~
~753~
and diluted for use as a toner in the proportions 20 ml - of concentrate to 1 litre isoparaffinic hydrocarbon dispersant.
In t~is instance the fusing temperature of the image ; 5. deposit was 96-104C. The plate~was cleaned after completion of the printing run by rubbing with a cloth pad wetted with methylene chloride.
In addition to being uneffected by the components of the jobbing black offset-printing ink used, the image 10. deposit of these examples was also uneffected by the components of an offset printing ink suited to heat transfer calender printing of textiles.
E~MPLES 5 - 8 Each of examples 1-4 were repeated using a dye 15. sensitised photoconductive recording member, which was exposed after charging using a fibre optic faceplate cathode ray tube controlled by an input signal corresponding to the information to be reproduced.
-20. Each of examples 1-4 were repeated using a dielectric recording member as the image bearing member. The dielectric recording member comprised a paper base having on one surface thereof a 5 gsm layer of polyvinyl J
butyral resin. The latent image was produced by stylus 25. wri~ing, using writing styli to which 500 volt negative pulses were applied from a control circuitry to produce an electrostatic latent image thereon corresponding to alphanumeric information~
11 .
~753~
Each of examples 1 to 12 were repeated with the exception that the printing plates were in the form of continuous cylinders o~ grained aluminium and grained 5. zinc respectively. In these examples electrostatic image transfer was car~ied out directly on the printing press, the electrostatic transfer means comprising a roller attached to the printing press to form a nip between said roller and the prin-ting cylinder through which nip the 10. developed recording member was passed to ef~ect transfer o the image deposit contained thereon to the printing cylinder. , Examples 3 and 4 were repeated with the exception 15. that the crushed epoxy resin ~as replaced with a crushed epoxy resin, epoxide equivalent 450-525, melting range 64-74C, specific gravity 1.2.
i Examples 3 and 4 were repeated with the exception 20. that the crushed epoxy resin was replaced ~ith a crushed solid epoxy resin, epoxide equivalent 575-700, melting range 80-90~o Examples 1 and 2 were xepeated with the exception 25. that the electrostatic latent image on thç electro-photographic recording mem~er was de~eloped using a liquid dispersed toner of the Eollowing composition:
~L~7~3~
Alcohol sol~ble resin maleic ester, 30 grms - Acid No, 110-125, SG 1.08, melting point 130-140C.
Resinated carbon black, hydrocarbGn 15 yrms 5. dispersible, such as Microlith Black CT, by Ciba-Geigy.
- Isoparaf-finic hydrocarbon250 grms These components wer~ ball,milled together for 72 hours, and diluted for use in the proportions 20 ml of concentrate 10. to 1 litre isoparaffinic hydrocarbon dispersant.
The plate was cleaned after completion of the printiny run by rubbing with a cloth pad wetted with butanol.
Examples 1, 3 and 29 were xepeated with the exception 15. that the grained al~ninium printing plate was replaced with a tri-metal plate, the wacer accepting,surface of which was electroplated chromium.
There has been described an imaging method and means whereby printing deposits can,be produced on offset printing 20. surfaces. The herein described method and means is suited to the formation of printing deposits'on continuous printing surfaces, which has not heretofor been known in relation to offset lithography. In addition the disclosed method and means allows reuse of the prin~ing surface on completion 25. of the printing run.
13.
Claims (5)
1. A method of preparing a reusable lithographic printing surface comprising the steps of:-producing an electrostatic latent image on the surface of 2 dielectric recording member, developing said electrostatic latent image by the attraction thereto of oleophilic electro-scopic marking particles, transferring electrostatically said oleophilic electroscopic marking particles from said dielectric recording member to a hydrophilic metal surface, and fusing said transferred oleophilic electroscopic marking particles to said hydrophilic metal surface by the application of heat to form a lithographic printing surface containing oloephilic printing areas and hydrophilic non-printing areas, said oleophilic electroscopic marking particles being characterised by the inclusion therein of resinous material selected to be resistive to components of the lithographic printing ink which is to be used in conjunction with such lithographic printing surface, and said resinous material being further selected to be soluble in a solvent selected from the group of ketones, alcohols and chlorinated hydrocarbons.
14.
14.
2. A reusable lithographic printing surface consisting of a hydrophilic metal surface having formed thereon oleophilic printing areas, characterised by said oleophilic printing areas comprising oleophilic electroscopic marking particles transferred thereto and heat fused thereon by raising the temperature of said oleophilic electroscopic marking particles contained on said hydrophilic metal surface to a temperature within the range 64°C
to 140°C, said heat fused oleophilic marking particles being characterised by the inclusion therein of resinous material selected to be resistive to components of the lithographic printing ink which is to be used in conjunction with said lithographic printing surface, and said resinous material being further selected to be soluble in a solvent selected from the groups of ketones, alcohols and chlorinated hydrocarbons.
to 140°C, said heat fused oleophilic marking particles being characterised by the inclusion therein of resinous material selected to be resistive to components of the lithographic printing ink which is to be used in conjunction with said lithographic printing surface, and said resinous material being further selected to be soluble in a solvent selected from the groups of ketones, alcohols and chlorinated hydrocarbons.
3. A reusable lithographic printing surface as disclosed in claim 2, further characterised by said oleophilic printing areas being removed after completion of lithographic printing from said hydrophilic metal surface by the simultaneous action of said solvent for said resinous matter contained within said oleophilic printing areas and of friction.
4. A lithographic printing plate having on one side thereof a lithographic printing surface as disclosed in claim 2.
5. A lithographic printing cylinder having its outer cylindrical printing surface as disclosed in claim 2.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU873574 | 1974-09-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1075300A true CA1075300A (en) | 1980-04-08 |
Family
ID=3699448
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA234,743A Expired CA1075300A (en) | 1974-09-02 | 1975-09-02 | Offset printing |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS6341746B2 (en) |
| CA (1) | CA1075300A (en) |
| DE (1) | DE2539025A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4533611A (en) * | 1982-04-29 | 1985-08-06 | Hoechst Aktiengesellschaft | Process for preparing a planographic printing plate |
| US5213041A (en) * | 1991-06-28 | 1993-05-25 | Man Roland Druckmaschinen Ag | Method and system for fusing printing image deposits on surfaces of a printing substrate, and removal thereof for re-use of the surface |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL8003134A (en) * | 1980-05-29 | 1982-01-04 | Veco Beheer Bv | METHOD AND APPARATUS FOR FORMING A METAL PREPARATION USING A PHOTO SEMICONDUCTIVE MATERIAL |
| JPS57211161A (en) * | 1981-06-23 | 1982-12-24 | Dainippon Printing Co Ltd | Production for flat printing plate |
| JPS593450A (en) * | 1982-06-30 | 1984-01-10 | Fuji Photo Film Co Ltd | Engraving method of electrophotoengraving material |
| JPS60119576A (en) * | 1983-12-02 | 1985-06-27 | Fuji Photo Film Co Ltd | Production of lithographic printing plate |
| TR24835A (en) * | 1990-07-07 | 1992-05-01 | Thomson Brandt Gmbh | TELEVISION TRANSFER SYSTEM |
| DE4216636C2 (en) * | 1992-05-20 | 1995-11-23 | Roland Man Druckmasch | Process and device for erasing and hydrophilizing a printing form imaged by means of a thermal transfer process |
| US6006666A (en) * | 1992-05-20 | 1999-12-28 | Man Roland Druckmaschinen Ag | Method and apparatus for erasing the ink-carrying layer from the surface of an image-containing printing form |
-
1975
- 1975-09-02 CA CA234,743A patent/CA1075300A/en not_active Expired
- 1975-09-02 JP JP50106461A patent/JPS6341746B2/ja not_active Expired
- 1975-09-02 DE DE19752539025 patent/DE2539025A1/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4533611A (en) * | 1982-04-29 | 1985-08-06 | Hoechst Aktiengesellschaft | Process for preparing a planographic printing plate |
| US5213041A (en) * | 1991-06-28 | 1993-05-25 | Man Roland Druckmaschinen Ag | Method and system for fusing printing image deposits on surfaces of a printing substrate, and removal thereof for re-use of the surface |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2539025A1 (en) | 1976-03-11 |
| JPS6341746B2 (en) | 1988-08-18 |
| JPS5153914A (en) | 1976-05-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |