US2800077A

US2800077A - Planographic printing plates and methods for manufacturing same

Info

Publication number: US2800077A
Application number: US278871A
Authority: US
Inventors: Thomas U Marron
Original assignee: AB Dick Co
Current assignee: AB Dick Co
Priority date: 1952-03-27
Filing date: 1952-03-27
Publication date: 1957-07-23
Anticipated expiration: 1974-07-23
Also published as: US2970534A

Description

July 23, 1957 T. u. MARRON 2,800,077

PLANOGRAPHIC PRINTING PLATES AND METHODS FOR MANUFACTURING SAME Filed March 27, 1952 PLANOGRAPHIC PRINTING PLATES AND METH- ODS FR MANUFACTURING SAME Thomas U. Marron, Glenview, Ill., assignor to B. Dick Company, Niles, Ill., a corporation of Illinois Application March 27, 1952,'seria1`No. 278,871

4 claims. (cl. 10i-149.2)

nited States Patent4` `C portion formed of an ink receptive, water repellentmate.- p

rial formed or applied onto a surface which beyond the imaged portion is hydrophilic and preferentially receptive to water or other aqueous medium. Thus if the surface of the plate in use is iirst wet with an aqueous repellent composition and then has an oil type ink composition applied thereto, the repellent solution will wet out the non-imaged portion of the surface and the ink composition will be received only by Vthe imaged portion for transfer in the production of copy yby the direct or offset method. At the present time an imaged lithographicplate of the type described is produced generally by two systems hereinafter referred to as the direct image plate 'and the indirect image plate, which develops the image on the surface of the plate by reaction to light or certain light rays resembling photographic processes ofthe like.

In the direct image plate, the surface is formed `of a hydrophilic material which is preferably insolubilized to i resist deterioration in water and the image is formed thereon directly by inscription with a writing instrument,

pencil, crayon, or by transfer of the ink forming composition from a typewriter ribbon upon impact by keys.

There are a number of limitations'in the manufacture and use of present direct image plates whichlit is desirable to overcome or at leastminimize asV much as possible. For example, the production of alargenumber dffcopies of good quality requires that the image forming `material applied to the plate surface becomes strongly anchored thereto, otherwise the image will walk oli? of Vthe plate in use. Strong anchorage has been found diflicultto achieve in View of the vast differences in the physical properties of the respective materials. Generally, the lithographic surface is hydrophilic in character to repel inkfcomposition and preferentially to receive aqueous repellentwhile the image vforming material is hydrophobic inv character to provide for ink receptivity and'water repellency. -The coniiicting properties quite naturally oppose 'the -development of a strong interbonded relation between the hydrophilic surface and the image formed thereon andlimits the number of copies of gcodquality that-'can be produced therefrom.

Considerable care `must be exercised in thevproper selection and application of imaging materialffor particular plates and the imaging operation poses jmany'undesirable steps which have heretofore been considered necessary and conducted as a matter of course but'can now be eliminated with the use Vof structures embodying features of this invention which will hereinafter be described.

No one may have raised the point that Ait 'would be desirable to eliminate the use of special ribbons, crayons or imaging solutions or that it would bedesirable `to eliminate the use thereof entirely in the production of an image on a lithographie or hectographic plate but have, as a matter of necessity, painstakingly threaded typewriter ribbons or lled drawing instruments with imaging compositions for transfer to the. surface ofthe lithographic or hectographic plate. l

The above merely points out a few. of the undesirable characteristics of present plates which can be overcome in accordance -with the practice of this invention.

The concepts of this invention vrelate Vto direct image plates and it is an object of this invention to produce a new and improved lithographic plate which overcomes many of the objectionable characteristics in the production and use of present plates andV it is a related object to proice 4duce a new and `improved imaged lithographie platev` of Another object is to produce a lithographie plate of the type described but in which the steps of imaging the plate do not reqiure the inscription thereon with an ink receptive, water repellent material.

VA further object is 'toproduce a lithographie plate of the type described in which the ink receptive image forming material constitutes a component originally embodied in the plate and it is a related object to provide for the development of an image thereon which is strongly anchored into the surface.

A still further object is to produce a direct image lithographic plate which may be simply Vand economically manufactured and which permits the development of an ink receptive image thereon in an expedient manner without the applieationof imaging compositions.

Another object isto produce a structure which, in itself, may not constitute a lithographic plate but which may be used in the manner described herein for, the development of an-ink receptive image on another lithographie surface in` a new and novel manner and it is a related object to produce a structure of the type described which may be freely handled'as an incidence to normal use without being subject `to the transfer of colored inking substances onto the hand or other objects. l p

,A ,further object is to provide a new and improved Vstructure for use as a direct'image lithographic plate or for use 'in the manufacture of a lithographic plate andit is a related `object to provide a new andim'proved method for developing an ink receptive imaged `portion thereon by indirect process.

A still further 'object is to produce a direct image lithographie plate of the typedescribed which embodies greater flexibility in the composition and in the characteristics of the image forming material and the water receptive material so as to provide for an improved application and use. v

These and other objects and advantages of this invention will hereinafterfappear and for purposes of illustration but not of limitation, embodiments of the invention are shown in Vthe `accompanying drawing in which- Figure l is an enlarged sectional elevational View of a lithographic plate embodying features of this invention; n 'Figure 2 is 'a perspective view in section of the plate Ashown in Figure l illustrating `the reactions occurring therein upon lbeing struck by a typewriter key;

`Figure f3 is a perspective view in section of the plate of Figure 2;

Figure 4 is a .perspective view in section showing the ystructure of Figure l imposition of usefor the preparation of an imaged .plate on another lithographic surface;

Figure 5 lis 'a `topplan fview of-the imagedlithographie plate produced bythe process of Figure 4;

Figure `6V is laysectional elevational -view of the .plate ink receptive image thereon.

shownin Figure l illustrating a modified method for forming the image thereon, and

Figure 7 is a top plan view of the im ge plate pro- 'duce'd'by the process ofl Figure 6. i

Although the objects of thisV invention 'appear to be `somewhat contradictory incharacter, they are all capable of achievement by the use of a lithographicplate prepared yifi-accordance with the practice of this invention having a lithographie surface which differs 'basicallyxfrom anything which has heretofore been produced. yBriefly ldescribed, a lithographie plate embodyin'gfeatures of.y this invention is formed with a lithographi'clcoating 10 yin the form of a polyphase system having a film forming, hydrophilic, water receptive4 material 11 :asf vthe continuous 'phase and an ink receptive,iwater repellent material i2 as the dispe'rsf'etl phase. The continuous phase-.con-

-stitutesza rupturable medium whichv insulates the'ink receptive water repellent material dispersed vtherein as minute particles or droplets. Thusthecoating presents a hydrophilic, water receptive surface but, in response Vto pressure as effected rby the impact ofa typewriter key Vi3, or by a writing instrumentor other .applied force,

the dispersed phase becomes liberated 1in corresponding areas, as illustrated by numeral dfto. provide an gink receptive, water repellent imaged portion 15 on the surface. When used in the normal manner for lithographic duplication, repellent then-preferably wets out the nonimaged portion while ink composition'is received by the -imaged portion 'formed in the areasV of liberated ink receptive material for transfer onto copy as ,previously described.

Upon liberation of the ink receptive material responsive to impact or other applied force, transfer may simultaneously be effected onto a surface of another lithographic plate in surface Contact 'therewith to form the In this capacity, the polyphase layer existing on a suitable base sheet functions in the manner of a typewriter ribbon or carbontype transfer sheet but without being subject to the objection- Vable features of such transfer sheets or typewriter ribbe selected of such film forming hydrophilic colloids as gelatin, glue, casein, polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, carboxymethyl hydroxyethyl cellulose, sodium alginates and the like, preferably insolubilized to resist deterioration by moisture under conditions of use. i

The hydroxy and amino-containing film forming materials, such as casein, zein, polyvinyl alcohol, cellulose ethers, cellulose esters and their salts and the alginates may be insolubilized by reaction with an aldehyde, such as formaldehyde, glyoxal or alum or other tanning agents incorporated directly with the colloid as an ingredient in the coating composition or applied afterwardsV byrwashing the surface with a solution thereof. lThe'cellulose ethers and their salts and polyvinyl alcohol may also be insolubilized to a desired degree by treatment with acids or `acid salts of the type hydrochloric acid, aluminum chloride, iron chloride, zinc chloride and the like', preferably applied as a Wash coat after. the hydrophilic colloid surface has been formed. Application of j the insolubilizing agents as an ingredient in the coating composition may range from 0.5 to 5 percent by weight and treatment as a wash coating may be achived with solutions having a concentration of 2 to 25 percentby weight of the insolubilizing agent dissolved therein.

Reference is made to the issued Patents Nos. 2,534,558,`

2,534,650 and 2,542,784 for amounts ofinsolubilizing agents required and the methods of application.

-Y in which ,it is to bedispersed. kIt is preferred to maintain Yrange from 3 to 15 percent by weight.

The dispersed phase having a base formed of ink receptive and water repellent materials may be compounded of an oily, greasy or waxy base, such for example as natural waxes including carnauba wax, ceresin wax, Japan wax, montan waX and the like; natural waxes such as paraffin waX or other microcrystalline wax; bitumens such as asphalt; fatty acids'such as stearic acid, palmitic acid, oleostearic acid land the like; or'fatty acid amides such as stearamide; pentaerythritol, sterols and the like; or oils such as castor oil, cotton seed oil, hydrogenated castor oil, linseed oil, mineral oils and the like. If the polyphase coating is itself adapted to providethe lithographic surface, the dispersed phase may be formed of solids substantially incapable of uid ilow but, in the event that the polyphase layer is to function as a transfer medium for depositing the hydrophobic ink receptive material released therefrom to an adjacent surface, then Vit is preferred tovcompound thedispersed' phase for ow lsufficient to effect the desiredtransferontothe lithographic surface in contact therewith. Fonsuch purpose,

1- the dispersed phase may beformed Yof oily or greasy substances capable of ow underthe-conditions of use or, in

' The amount of hydrophilic colloid coating and ink which is used in solution to form the continuous phase.

methyl cellulose and other cellulose salt derivatives may Casein, zein, glue and albumenand the like may be used in concentrations ranging from 5 to 25 percent by weight depending, `in part, on the amount of ammonia or other alkalizing Vagent present.

tion ofthe ink receptive substance can best be defined in relation tothe amount of hydrophilic film forming mateiial the ratio between the materials forming the continuous l phase and the dispersed phase Within the range of 3 parts v by Weight of the continuous phase toil to 3 parts by Weight f ing from 2 to l0 mils. Where bending is of lesser import- .'ance, layers as thick as 20 to 25 mils may be used. The

thickness of coat may be controlled by the amount of composition applied per unit area Within limitations compatible with the production of a uniform layer of desired density. Not infrequently in the pijoduction of relatively thick layers, it is expedient to deposit a number of thin coats in vsuccessive operations to build up the desired thickness. Coating may be accomplished by conventional means such as by a roller coater, brush ooater, spraying,

. knife coater or by the use of an air blade to control the thicknessanddistribution of the coating composition as described in the copending application of Mullen, er. No.

206,866, now Patent No. 2,721,815. v

In the manufacture of a planographic printing plate embodying features of this invention, it is preferred to make use of .a backing sheet 16 upon which the coating composition may be applied to form the polyphase layer of desired thickness. For a bendable plate of sufficient flexibility to permit use in a typewriter, the backing sheet Glyoxal (30 percent solution) is preferably formed of thin sheet .stock such as paper, plastic film, metal foil or the like. Where flexibility isunimportant, plates of metal, glass, plastics, berboard, cardboard or the like maybe used. v v

. For a short run plate, that is a plate Vadapted for the A production of 1-0-50 copies; it may be suilicient to use ordinary paper, but it is preferred" to make usefof a high wet strength or waterproof paper, such as-the 'type-having a resinous material represented by urea formaldehyde, melamine fofmaldehyde vor phenol formaldehyde incorporated therein or else treated with awaterproofingmaterial such asr oils,4 waxes, varnishes,'-lacquers Aor the like.

of paper sheets especially prepared with a sur-facehighly receptive to the `coatingcomposition, such as the coated sheets of the above mentioned copending application of Mullen. When the surface ofthe base sheet is coated with a hydrophilic colloi'd to provide -a receptive base for the polyphase system, the thickness of thel'l'nolyphase layer lmay be decreased. f j

It has been found that `the vcharacteristics of the plate may be'improved Aby the us'e of an `inert filler addedv .to

Parts by weight Methyl cellulose (25 cps. viscosity) the methyl-cellulose and glyoxal in Water. and'then dis-l persing the 'castor oil intoy the solution.

` Example 2 In the manufactureof a low'run plate, the coating compositionof `Example 1 is applied by roller-coater technique in amounts to form a layer of l mils thickness 'onto a sheet of partially hydrolyzed cellulose acetate. A polyphase layer of about 2.5mils is formed upon drying at 4room temperature followed by subsequent heating at 105 f' for 30 minutes.

` Example 3V A solution is first formed of a film forming material and is formulated to contain 30 grams hydroxyethyl cellulose percent solution), 25 grams ethylene glycol and 5 grams glyoXal (30 percent solution). A separate emulsion is formed of 5 grams stearic acid, 50 grams castor oil and 5 grams morpholine in 300 grams of water. The emulsion is diluted ten-fold and then .incorporated with the solution of lm forming material in lamounts `to dilute the solution up to 300 ml.

The composition formed is applied onto 60-pound wet strength kraft paper by a dip coating process to form a nlm of about 8 mils thickness which upon drying'at room temperature and subsequent heating for 40-60 minutes at 105 F. provides a polyphase layer having a thickness of about 2 mils.

Example 4 Percent Casein 16.0 Formalin 3.5 Ammonia `1.5 Parain wax 10.5 Mineral oil 2.0 Water 66.5

-Iphase film having athickness of about 5 mils when dry.

. Instead, the polyphaseY layer may be formed on the surface -V The parafn, Waxfsand mineral oil are `dispersed in the solutionA formed of casein, formalin vand ammonia `in Water. VThe coating composition, in the manufacture of a relatively long run plate,is applied by a brush coater to form a layer ofi-5 mils thickness onto the surface of a Y resinous'treatedpaper base sheet l'of the typede'scribed in "the aforementioned Mullen application. After drying the coating at elevated temperatures, va second `layer ofthe coating"compositionislapplied 'after prewetting to deposit another vlayer of about 8 mils thickness to form al polyl Example A Parts by weight Casein V... Formalin 3 Ammonia 1.5 Clay 40 Castor oi1 8 .'Stearic aci;l 1

The casein, yformaldehyde and ammonia is taken into Y'solutionin water and cla'y dispersed therewith. Then the castor foil andr'stearic v'a'cidlis emulsiiied `Within the solutionand the composition diluted to percent by 'weight solids.y

Example 6 I l. Percent by weight Sodium alginate 3.0 Carnauba wax 1.0 .'Minera1`oil t .5 Water 95.5

' 'Example 7- f Percent by weight Polyviny11 a1coho1 (low viscosity grade) 15 Castor oil l0 Water 75 The water soluble substances in the above compositions 4are 'dissolved in V"aqueous medium and the ink receptive hydrophobic oily and waxy materials dispersed therein. The polyphase systems are applied by conventional tech- ,nique onto Vthe surface of a receptive base sheet in amounts to provide the desirable thickness. After the coatings of Examples `6fand.7 have dried, insolubilization of the alginateand the polyvinyl alcohol may be 1achieved by Washingfthe surface .with a 5 percent solution of zinc chloride. The hydrophilic casein of Examples 4 and 5 become insolubilized uponwdrying by reaction with the formaldehyde contained therein and further insolubilization may be achieved by 'an after treatment with a 5 to l5 percent solution of a mineral salt such as zinc acetate, zinc chlo- 1 ride or thelike, or by an additional treatment with forme aldehyde dissolved in aqueous medium.

` plate may be positioned to have the keys of the typewriter impact the backside of the plate. In response to the irnpact pressure, the dispersed ink receptive, water repellent material 12 is liberated from the polyphase system, possibly due to rupture of the continuous lm in the impacted areas, whereby the imaged portion 15 in reverse is formed onthe surface of the polyphase coating to provide the ink receptive, water repellent imaged portion surrounded by the Water receptive surface of the hydrophilic material forming the continuous layer.

If the plate is inserted in the typewriter to present the polyphase vcoating to impact directly by the keys or to receive other pressure tool, the image formed will be in proper dimension for offset printing. It is preferred to place an interlayer sheet of paper or the like adjacent the polyphase coating so as to militate against transfer of the liberated ink receptive material onto the platen or to the 'typewriter keys.

When mounted on the duplicating machine for the production of copies, repellent which is rst applied wets out to duplicate the image thereon.

the surface covered by the continuous phase of `hydro- `philic material and then the inkmaterial which is later applied is received only by the imaged vportion for ,transfer to the copy by direct or oisetmeans depending upon the manner in which the image is located on the plate. il

When properly adjusted, thepressure developed between the plate surface and the offset andinking cylinders is insuicient to cause rupture of the continuous phase of the lithographie coating whereby the non-imaged portion remains water receptive and the formed image maintains its specific letter outline to produce'copy of good quality.

When the polyphase coated structure is to be used as a transfer sheet, such as a'"carbon or typewriter ribbon in the preparation of an ink receptive image upon a separate lithographie surface,'as illustrated inFigure4,-the'c oated 'sheet 20 is positioned substantially in surface Vcontact with the lithographie surface 21 ofthe lithographie plate 22. Upon impact by a typewriter key'23 orupon the'application of pressure to release the dispersed ink ^receptive phase in corresponding areas, the'liberated ink receptive( material 24 transfers to the surface 25 of the lithographie plate to form the image 26 thereon.` VTo form theimage in reverse for direct printing, the force is appliedin Athe desired letter outline through thec'oated sheet preparedin accordance with this invention having the lithographie surface 25 in contact with the polyphase layer 27. If the image is to be formed on the plate in direct order for offset printing, the letter outline is impressed through the transfer sheet containing the polyphase coating/ An important feature of thisV invention resides -also'in` the utilization of the concepts described and claimed herein in the manufacture of a'master for heetograph duplication and particularly for use'in spirit duplicating systems.

In spirit duplicating Yprocesses as they are presently known, the image is formed on the surface. of a hectograph plate by inscribing,.drawing, typing. or die-impressing to apply a composition containing ahigh concentration of a water soluble dye in a base capable of being removed slowly as by solution in Water or valcohol or a combination of water and alcohol or other solvent. The design or letter outline on the surface of the heetograph plate is then contacted in the duplicating machine with copy paper which has previously been moistened by an aqueous system. A portion of the dye forming the image is dissolved in this medium and consequently transfers in part from the heetograph master to the impression paper A substantial number of copies can be made from the heetograph master before the dye is removed therefrom in suicient quantity to` militate against production of good copy.

It will be apparent from this description that the problems in forminga suitable image on the heetograph master and the use thereof in the manufacture of copy of good quality corresponds in many kways to the practice with the lithographie plate.

Therefore, it is an object of this invention also to produce and to provide a method for producing a new and improved heetograph plate and it is a related object to provide means for producing an imaged plate without inscription with imaging materials. Y Y

More speciiically, it is an object of this invention to incorporate all of the objective sought for a lithographie plate into the manufacture of a new andV Vimproved hectographic plate.

In the manufacture of a hectographic plate in accordance with the concepts embodied-in this invention,'the materials adapted for use in forming the continuous phase of the polyphase system are not limited to hydrophilic tilm forming materials but may'in fact andpreferably are selected of tilm forming materials which are not soluble in water or solvent system'used for transfer Vof the coloring medium by hectographic technique. Thus `the continuous phase may be formed of such highly resistant lm formingmaterials as polystyrene, polyvinylidine `chloride`,polyalkyl acrylates such as polyrnethylmethacrylate, polyvinyl acetate, vinyl chloride-vinyl acetateV copolymer, polyvinyl: acetal or butyral, or cellulose ethers and esters of the type nitrocellulose-ethyl cellulose, cellulose acetate, cellulose butyrate and Vthelike resinous materials, or rubber or synthetic elastomeric 4pounded with o r withoutplasticizers or softeners.y

The dispersed phasejmay beV formed of a base `subv-stance which can be slowly dissolvedV in an alcohol or of this invention.

and derivatives thereof.

an alcohol and water system such as of waxes ofthe type 15 paraflin wax, montan wax, esparta wax, beeswax, petrolatum andthe like, alone or in `admixturewitheach. other. Use may also be made. of fats and oils such'as hydrogenatedcastor oil, tallow oils, vegetable oils, animal oils Iny order to secure suicient flow for use in transferring to a hectographic surface in the event that the structure embodying.` features of this invention comprises a carbon type or other transfer sheet, plasticizers or softeners may be incorporated with the materials,` such kfor example as mineral oils, castor oils, petroleum oils, polyethylene glycols, triethylene glycols and the like.` k V VThe material forming the continuous phase is preferably formed of the water soluble iilm forming substances previously described in the event that the image is to be formed drirectlyin the polyphase layer. If the polyphase layer is to operate as a transfer mediumkfor depositing the image on an adjacent receptive surface, then the continuous phase may be formed of any lm forming material including not only the resinous andvrubber-like substances previously described but also the hydrophilic film forming materials used to form the continuous phase in the manufacture of a lithographie plate heretofore described. s

The concentration of film forming material in the coating composition may be variedV consistent with a suitable viscosity for use of the treating composition in coating. The amount very often depends upon the spe-l cic vmaterials and may range from 15-30 percent by weight polystyrene, 10-20 percent by weight polyvinylidine chloride, 10-30 percent by weight butadiene-acrylonitrile copolymer and 10-20 percent by weight rubber hydrochloride. The ratio of dispersed phase toV continuous film forming material may correspond to the amounts used in the manufacture of lithographie plates and the thickness of iilrns desired 'to be deposited on the backing sheet remains substantially the same. Suitable dyes for use as an ingredient in the dispersed phase may be selected of the rhodamine dyes, salfranine, Victoria green or the like.

Example 8 Percent Vinyl chloride-vinylidine chloride copolymer 15 Methyl ethyl ketone A composition containing 40 percent parain wax, 50 percent Victoria green dye and 1() percent petroleum oil is dispersed in the solution of vinyl chloride-vinylidine chloride copolymer and the dispersion applied onto a high wet strength paper by a brush ccater in amounts to supply a layer having a thickness of about l0 mils. Upon air drying and heating for a short time at a temperature of about F., a polyphase layer is formed having a thickness of about 3 mils.

The above is merely representative of the manufacture of a hectographic plate embodying compositions It .will be understood that'other lrn forming materials may be `substituted for polystyrene within the dened amounts and that other waxy or oily substances in various combinations may be substituted in whole or in part for paraflin in the dispersed phase.

When the prepared plate is impacted with a typewriter liey or other writing instrument for producing the image on the hectograph surface, the wax base composition containing the dye as the dispersed phase is liberated to form the corresponding image on the surface for subsequent use as an imaged plate in normal duplicating operations. Instead of forming the image on'the plate surface, the liberated hectograph medium may be transferred onto a hectograph surface in contact therewith and the other plate mounted in the duplicating machine for' the production of copies therefrom.

When mounted in the hectograph duplicating machine, the impression paper is wetted on one side with an aqueous alcoholic solution and then pressed into surface contact with the imaged plate whereby a portion of the imaging composition is dissolved and transferred to the impression paper in the production of copy.

A new and novel concept of this invention also resides in the technique for developing an image on the described planographic masters by a method wherein a heat pattern is developed by directing radiations rich in infrared from a light source onto an original 31 in surface contact with the polyphase coating 32 of the planographic plate 33. The infra-red radiations 34 are absorbed by the letter outlines 35 of the original 31 and converted into heat 36. A heat pattern is formed which transfers to the polyphase layer 32 and is sufficient to cause rupture of the continuous film forming phase in corresponding areas or for other unknown reasonsapparently liberates the ink receptive or separate ,soluble dispersed phase 37 to form an image for use in lithograph or hectograph duplication, respectively. Instead of forming the image on the polyphase layer, transfer may be effected to a receptive surface in contact therewith, as in the transfer sheets previously described. In the latter event, the original may be placedl adjacent the master or addesigns which may be formed for transfer in the imaged jacent the transfer sheet. Considerable advantage results' in transfer systems of the type described when the dispersed phase is compounded with a base substance reducible to owable condition at the elevated temperatures developed.

It will be apparent from this description that there is provided a planographic master which is characterized by exceptional response to impact or pressure and heat to develop an imaged portion thereon for use in duplication by lithographie technique or hectographic technique or to transfer an imaged portion onto a surface and form a master for hectograph or lithograph duplication.

It will be apparent that a transfer sheet of the type produced by this invention is capable of being handled without causing colored material to dirty surfaces or objects in contact therewith thereby to permit use without being subject to the undesirable features of normal carbon sheets, typewriter ribbons or other transfer structures now in use.

More important, preparation of an image for lithograph or hectograph duplication can be achieved without the use of such ribbons, carbons or other transfer materials inscribed upon the surface of the master'thereby to eliminate one elementand operation in the preparation of a duplicating master. In addition, a wide variety of materials may be compounded in the dispersed phase or in the continuous phase to enhance the bonding relation between the two substances in effecting a more permanent imaged master and to impart a liexibility in reproduction and in imag fore been available to thV The structure embodying feat vides a radically new concept in the plicating masters and the production of im It will be apparent that numerous other advan naturally from structures of the type described an greater latitude is provided with respect to the colors an the plate and consists of a polyphase system having a hydrophilic, water insoluble, film forming colloid as Vthe continuous phase and a dispersed phase of an ink receptive, water repellent imaging material which forms an ink receptive image on the lithographie surface when released to the surface of the coating from the polyphase system in the imaged areas.

2. A lithographie plate as claimed in claim l in which the materials forming the polyphase system are present in the ratio of 3 parts by weight of the material forming the continuous phase to 1-6 parts by weight of material forming the discontinuous phase.

3. An` imaged lithographie printing plate comprising a base sheet, a layer on the surface of the base sheet which forms the hydrophilic lithographie surface of the plate and consists of ,a polyphase system having a hydrophilic, water insoluble, film forming colloid as the continuous phase, and a dispersed phase of an ink receptive, water repellent imaging material which forms the ink receptive image-'on the lithographie surface when released from the polyphase system in the imaged areas, and an image formed of the ink receptive, water repellent material released from thepolyphase system to the surface of the coating with the unbroken polyphase system forming the non-imaged portion of the plate.

4. In the method of producing an imaged planographic printing plate the steps of coating a base sheet with a polyphasev system consisting of a continuous phase of `an ink repellent, water receptive, hydrophilic, film forming colloid insoluble in water and a dispersed phase of an ink receptive, water repellent hydrophobic imaging material, drying the coating on the surface of the base sheet to form the hydrophilic lithographie surface thereon, and applying force to the polyphase coating in the imaged areas to break the polyphase system for releasing the imaging material to the surface of the plate to form the image thereon while the remainder of the polyphase system forms the non-imaged hydrophilic portion of the plate.

References Cited in the file of this patent UNITED STATES PATENTS 1,245,120 Neidich Oct. 30, 1917 2,119,031 Wescott May 31, 1938 2,299,693 Green Oct. 20, 1942 2,374,862 AGreen May 1, 1945 2,503,758 Murray Apr. 11, 1950 2,534,650 Worthen Dec. 19, 1950

Claims

1. A LITHOGRAPHIC PRINTING PLATE COMPRISING A BASE SHEET AND A CONTINOUSLY LAYER ON THE SURFACE OF THE BASE SHEET WHICH LAYER FORMS THE HYDROPHILIC LITHOGRAPHIC SURFACE OF THE PLATE AND CONSISTS OF A POLYPHASE SYSTEM HAVING A HYDROPHILIC, WATER INSOLUBLE FILM FORMING COLLOID AS THE CONTINUOUS PHASE AND A DISPERSED PHASE OF AN INK RECEPTIVE, WATER REPELLENT IMAGING MATERIAL WHICH FORMS AN INK RECEPTIVE IMAGE ON THE LITHOGRAPHIC SURFACE WHEN RELEASED TO THE SURFACE OF THE COATING FROM THE POLYPHASE SYSTEM IN THE IMAGED AREAS.