Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/06—Silver salts
  • G03F7/063—Additives or means to improve the lithographic properties; Processing solutions characterised by such additives; Treatment after development or transfer, e.g. finishing, washing; Correction or deletion fluids
• • 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
  • B41N3/08—Damping; Neutralising or similar differentiation treatments for lithographic printing formes; Gumming or finishing solutions, fountain solutions, correction or deletion fluids, or on-press development

Definitions

• the present invention relates to lithographic processes and to lithographic printing plates made photographically.
• the printing plate comprises a support which when wet is oleophobic and carries a line or dot image which is oleophilic.
• the oleophilic properties of the image and the elecphobic and hydrophilic properties of the surrounding support surface are relative in nature to some extent.
• both ink and water are applied and the support is sufficiently hydrophilic to acceptwater but not the geasy ink, while the image accepts the ink but not the water.
• the diiference in hydrophilic and oleophilic properties of the image and v the background surface is sufiiciently great that when water and ink are applied, the image will accept sufiicient ink without the background accepting any ink at all.
• lithographic printing plates are supports the nature of whose surface is such that when wetted it will not accept the ink although if ink is applied when the surface is dry the ink so applied is not removed by subsequent wetting.
• the practice inmaking a photolithographic printing plate is to produce an oleophilic image on the hydrophilic support which can be put into an inking machine whereby large numbers of copies can usually be made very rapidly from the one plate.
• Aluminium sheet employed in the art is provided with an inert hydrophilic surface. This is often done by treating the aluminium to produce thereon an aluminium compound which is hydrophilic for instance aluminium oxide as in the case of anodised aluminium, aluminium silicate and chromatiscd aluminium.
• One object of the present invention is to provide a process which entirely avoids etching after formation of the image by making the image areas very oleophilic compared with the background areas.
• An object of the present invention is to provide a process which satisfies these requirements in a verysurprisingly simple way namely by forming a silver image on a lithographic printing plate and merely treating it with a special type of organic compound which is adsorbed to the surface of the silver and renders it oleophilic while having no appreciable elfect on the hydrophilic proper-,
• This treatment of the silver image with the solution can be very easily done by swabbing or rubbing a solution of the organic compound over the image for a few seconds using cotton wool.
• An important advantage is that there is nothing critical about this treatment. It is believed that the organic compound is rapidly adsorbed to the surface of the silver and this takes place immediately the solution is applied thus rendering the time of application very short and not critical.
• the present invention provides a'lithographic printing process which comprises forming on a lithographic printing surface a photographic silver image and bath ng the silver image in a solution of a sulphur or selenium organic compound containing an oleophilic group in the molecule and being a compound which when brought into contact with the silver at ordinary room temperature becomes integrated to the surface of, and only in the region of the silver and thereby renders the surface of the silver oleophilic by virtue of the oleophilic groups, inking the silver image with greasy printing ink and printing therefrom in a lithographic printing press.
• the support is free of metals and metal salts which are readily converted into oleophilic metal derivatives of said organic compound.
• the development of the diffusing silver halide must be sufiiciently greatto ensure that the developed image on the printing surface is built up to a suit-able high density at the surface.
• a lithographic printing process which comprises forming on a lithographic printing surface containing a silver precipitating agent a silver image from the diffusing silver halide of an exposed and developed silver halide emulsion layer in contact with the printing surface and then bathing the silver image so formed in a solution of an organic compound containing an oleophilic group in the molecule and being a compound which when brought into contact with the silver at ordinary room temperature becomes integrated to the surface of, and only in the region of'the silver and thereby renders the surface of the silver oleophilic by virtue of the oleophilic groups, inking the silver a image with greasy printing ink and printing therefrom in a lithographic printing press.
• organic compound In order that the organic compound shall be adsorbed to the surface of the silver it must contain in the molecule one or more groups having an aflinity for silver.
• groups include the following:
• R is a group which can easily be hydrolyzed off leaving SH, such as acoyl, aroyl, amidinium or NHR when R is alkyl, aryl, aralkyl, cyclo alkyl, heterocyclyl.
• the organic compound In order that the organic compound shall confer oleophilic properties on the silver, it must contain one or more oleophilic groups in the molecule. In general it is found that suitable oleophilic characteristics are conferred on the silver image if the organic compound contains a. fatty chain or a substituent containing at least four carbon atoms, e.g., potassium butyl xanthate.
• the fatty chain may be one of less than four carbon atoms, e.g., S-methyl isothiuronium salts, ethyl isothiuronium salts which split in alkaline solutions to give S-methyl mercaptan and ethyl mercaptan respectively, triazole mercaptans and tetrazole mercaptans.
• Organic compounds which contain the aforesaid groups in the molecule and therefore may be used in the present invention include the following:
• R is an alkyl or cycloalkane, preferably of, but not limited to, the range C to C
• These compounds have good stability when dissolved or dispersed in water or aqueous solutions of gum arabic or carboxy methyl cellulose.
• R is H2 H
• FORMULA 1 Compounds of this class can be prepared by the method of or analogous to the method described by Burke J.A.C.S., 69, 236-7 (1947).
• triazine thiols are l-dodecyl-l,2,4,5-tetrahydro-1,3,5-triazine-4thiol and l-octyl-1,2,4,5-tetrahydro-1,3,5-triazine-4-thiol.
• Thio acids and their salts such as thio-benzoic acid or potassium octylxanthate, dithiocarbamates, for exam ple diethyldithiocarbamate, zinc dibutyldithiocarbamate, the polysulphide derivatives of dithiocarbamates which are activated by alkali, e.g., tetraethylthiuramdisulphide.
• Thio amides e.g., phenylthiourea, N-(N-octylthiocarbamoyl) glycine, thiopropionanilide, phenylthiosemicarbazide.
• Isothiocyanates e.g., phenylisothiocyanate.
• the silver precipitating agents such as development nuclei on the lithographic printing support should preferably be free of particles of compounds such as zinc sulphide because many of the said organic compounds having the properties required for making the surface of the silver oleophilic chemically react with zinc sulphide to convert it into the metal derivative of said organic compound, and we have found that such conversion of the zinc sulphide nuclei in the background renders those nuclei sufficiently oleophilic to cause the background to accept visible amounts of ink unless the plate is wetted extensively when making the copies therefrom.
• nuclei of for instance silver or silver sulphide, which are not converted into particles of a silver salt of the organic compound are the preferred kind of nuclei to employ in this invention. If a low concentration of zinc sulphide nuclei is used in order to try to avoid this difficulty caused by the conversion, there are insutficient nuclei to yield a sufficiently strong surface image.
• the development nuclei comprises silver or silver sulphide it is necessary to use as little colloidal binder as possible for holding the nuclei on the surface of the support since if too much binder is used, the silver image which is formed is protected by the binder and is not sufficiently strong at the surface to operate satisfactorily in the linking process. It is preferable to obtain adherence between the nuclei and the surface by means other than using a colloidal binder.
• an excellent support to use in our invention is aluminum the surface of which comprises a hydrophilic aluminum compound, for example we prefer anodised aluminum.
• Other supports may be used in the present invention for example, grained zinc chemically treated to produce a hydrophilic lithographic surface, and paper lithographic supports.
• a thin hydrophilic layer such as a layer of casein or silica or polyvinyl alcohol with suitable fillers if necessary and then silver nuclei may be deposited thereon and will adhere thereto.
• Various plastics may also be used as supports, for example surface hydrolyzed cellulose ester sheetings.
• a suitable nucleated surface can be produced on aluminium which has been treated to convert the surface into a hydrophilic aluminium compound for use in making printing plates by the present invention by merely bathing the surface of the aluminium with a colloidal solution of silver or gold or silver sulphide.
• An alternative but less convenient way of forming such nuclei on the aluminium surface is to bathe the aluminium surface first with a solution of silver nitrate followed by bathing with sodium sulphide thus producing nuclei of silver sulphide.
• nucleating layer is formed by simply bathing the anodised aluminium in a simple aqueous colloidal solution of silver this ensures that the amount of the silver which is absorbed by the anodised aluminium surface per unit area is extremely low and no colloid binder is necessary.
• Colloidal solutions of silver which may be used for this purpose are, for instance, those giving yellow, red or black solutions and containing between 0.1 and 0.001 mol of silver per litre.
• the simplest way of treating the silver image with the organic compound according to our invention is to form the silver image first and then merely apply to it a solution of the organic compound.
• the silver image may be formed in the presence of the said organic compound.
• the image can be treated with the organic compound by coating the organic compound on the aluminium plate before forming the image thereon and in this case the organic compound becomes adsorbed to the silver as the image is formed.
• adsorption of the organic compound by the silver image depends on whether the support has been specially coated with development nuclei, such as colloidal silver or silver sulphide particles and the concentration of such nuclei. If the concentration of nuclei is high then a black image of metallic silver is obtained with the organic compound adsorbed or partly adsorbed thereto. However if the concentration of nuclei is very low or nil a whitish image may result which comprises largely or wholly the silver derivative of the said organic compound formed by double decomposition of the silver halide with the organic compound. 7
• a two layer material may be usedin the present invention namely one in' which the receiving layer (which may contain development nuclei) is coated beneath the light sensitive silver halide layer it only being necessary to remove, such as by washing away, the latter layer after the silver image has been formed in the receiving layer.
• the emulsion layer may be for instance, a cellulose dib'asic acid ester emulsion layer described in the Yackel et al., US. Serial No. 586,705, filed May 23, 1956.
• Example 1 A silver sol is prepared by the classical Carey Lea method and is Well Washed and finally diluted to 1 gram in 100 cos. of distilled water. A sheet of aluminium 0.005 inch thickand anodised to give a tihckness of aluminium oxide of about 0.5 gram per square metre is bathed in this solution, the excess removed and the sheet dried.
• a high contrast negative material such as Kodak Chemical Transfer Negative Paper comprising a sensitive silver chloride emulsion is exposed either by transmission or by reflex and in conjunction with the prepared'metal receiving sheet is fedthrough a normal processing machine for the silver diffusion process such as the Remington Rand TC; 35, containing a developer of the following composition:
• the two sheets are squeegeed together as they emerge from the developer and are left in contact for /2 minute after which they are stripped apart and the transferred silver image on the aluminium receiving sheet is rinsed and then is swabbed for a few seconds with the following solution:
• Acetone ccs 50 Water do 50 The excess is removed'with a sponge moistened with a weak solution of gumarabic after which the image may be inked in the usual way either by hand or on a lithographic printing machine, and will give several thousands of copies.
• solutions which may be used for treating the silver image in the foregoing are: (a) 1 dodecyl vl,2,4,5 tetrahydro 1,3,5 tritetrah.ydrol,3,5 -triazine-4thiol in acetone is shaken vigorously with 50 ml. of a 5% aqueous. solution of carboxy, methyl cellulose to form a crude emulsion. i 0
• nucleated supports which may be used in the present invention are:
• Example 2 1 gram of chloroauric acid H(AuCl is dissolved in 500 ml. of distilled water, it is neutralized with 0.1 N potassium carbonate and heated. A few drops of a solution of White phosphorus in ether are added to produce a gold sol. This gold sol. is washed and diluted to 1 litre and a sheet of anodised aluminium bathed in it and dried.
• Example 2v This is the same as Example 2v except that the metal sheet instead of being anodised aluminium is a sheet of aluminium on the surface of which a fine sharp lithographic grain has been produced by a chemical etching technique to produce for instance an aluminum silicate or chromate surface, a suitable material being that sold commercially by Addressograph Multigraph for conventional lithographic platemaking.
• the metal sheet instead of being anodised aluminium is a sheet of aluminium on the surface of which a fine sharp lithographic grain has been produced by a chemical etching technique to produce for instance an aluminum silicate or chromate surface, a suitable material being that sold commercially by Addressograph Multigraph for conventional lithographic platemaking.
• Example 4 A lithographic paper plate sold by the Addressograph Multigraph Corporation under the name Blue Duplimat is first treated with a solution of 1% sodium sulphide in water for about 20 seconds and then washed for 2 to 3 minutes and dried off. This treatment is believed to form zinc sulphide in the Duplimat'coating by'the reaction with a soluble zincsalt already incorporated during manufacture of the material. Such treatment provides a suitable nucleated receiving layer.
• V lithographic paper plate sold by the Addressograph Multigraph Corporation under the name Blue Duplimat is first treated with a solution of 1% sodium sulphide in water for about 20 seconds and then washed for 2 to 3 minutes and dried off. This treatment is believed to form zinc sulphide in the Duplimat'coating by'the reaction with a soluble zincsalt already incorporated during manufacture of the material. Such treatment provides a suitable nucleated receiving layer.
• Example 5 A sheet of negative paper such as Kodak Chemical Transfer paper is exposed as in Example 1 and then together with a sheet of anodised aluminium carrying silver nuclei is fed through a processing machine as in Example 1, and using the same developer but also containing 5 grams per litre of 1-hexyl-l,2,4,5-tetrahydro-l,3,5-triazine-4-thiol. When the two sheets are separated the aluminium sheet carries a positive silver image which is oleophilic. It is wiped over with a 2% solution of gum arable and then inked in the usual way.
• negative paper such as Kodak Chemical Transfer paper
• Example 6 A sheet of anodised aluminium foil nucleated by treatment with a silver sol. as in Example 1 is coated with a thin layer of 0.5% solution of 1-octyl-l,2,4,5-tetrahydro- 1,3,5-triazine-4-thiol in ethyl alcohol and then dried off.
• a sheet of light sensitive halide negative material such as Kodak Chemical Transfer paper is exposed to a positive image and then in conjunction with the sheet of coated anodised aluminum foil is fed through a Remington Rand TC. 35 machine containing the same developer as in Example 1.
• the aluminum sheet bearsja black positive image.
• This sheet is then wiped with a swab containing ethyl alcohol to remove the unused triazine compound.
• a 2% solution of gum arabic is then wiped on the aluminium and then it is inked in the usual way.
• Example 7 A sheet of Blue Duplimat is treated with sodium sulphide as in Example 4.
• the paper plate is now wiped over with a 2% solution of hypo in water and dried 01f.
• a sheet of light sensitive silver halide negative material such as that supplied for the solvent transfer process, e.g., Kodak Chemical Transfer paper is exposed to a positive image, developed for about 20 seconds in the developer used in Example '1 but omitting the hypo, and then while still containing the developer it was laminatedinto contact with the paper Duplimat. After a few-seconds the sheets are separated and a positive image is visible on the Duplimat sheet.
• the surface of this sheet is now moistened with Platex solution or with a mixture of:
• Platex is a proprietory solution sold by Addressograph Multigraph Limited for treating Duplimat sheets.
• Example 8 A sheet of brush grained aluminium foil is surface anodized in the known manner to give an aluminium oxide layer of about 0.5 gram per square metre and coated with the following solution:
• a lithographic printing process which comprises forming on a support containing a silver precipitating agent a silver image from the diffusing silver halide of an exposed and developed silver halide emulsion layer in contact with the support and then directly bathing the silver image so formed in a solution of a compound of the class consisting of oleophilic organic compounds containing a thiol group, oleophilic organic compounds generating a thiol group, and selenium analogues of said compounds, inking the silver image with greasy printing ink and printing therefrom in a lithographic printing press.
• a lithographic printing process comprising forming on a support having development nuclei coated thereon a silver image by development of the diffusing silver halide from an exposed and developed silver halides layer in contact therewith and directly bathing the silver image on the support in a solution of a compound of the class consisting of oleophilic organic compounds containing a thiol group, oleophilic organic compounds generating a thiol group, and selenium analogues of said compounds, inking the silver image with greasy printing ink and printing therefrom in a lithographic printing. press.
• a lithographic printing process according to claim 1 wherein the support is free of metals and metal salts which are readily converted into metal derivatives of said organic compound.
• a lithographic printing process according to claim 1 wherein the support is aluminium which has been chemically treated to form a surface layer of a hydrophilic aluminium compound.
• a lithographic printing process which comprises forming on a nucleated support a photographic silver image by diffusing silver halide imagewise from an exposed and developed silver halide emulsion over the said support and removing the said emulsion, the step of directly after formation of the silver image bathing the image in a solution of a compound of the class consisting of oleophilic organic compounds containing a thiol group, oleophilic organic compounds generating a thiol group and selenium analogues of,said compounds, inking the silver image with greasy printing ink and printing therefrom in a lithographic printing press.
• a process for preparing'a photographic image from an exposed silver halide emulsion layer comprising developing the emulsion layer, transferring the silver halide from the undeveloped areas of the emulsion layer to a. support containing a silver precipitating agent in the presence of a silver halide solvent and directly following the formation of the silver image on the said support, contacting the silver image with an organic compound containing an oleophilic group in the molecule and selected from the compounds of the general formula wherein R is a member of the class consisting of alkyl and cycloalkane groups, inking the silver image with greasy printing ink and printing therefrom in a lithographic printing press.
• a process for preparing a photographic image from an exposed silver halide emulsion layer comprising developing the emulsion layer, transferring the silver halide from the undeveloped areas of the emulsion layer to a support containing a silver precipitating agent in the presence of a silver halide solvent and directly following the formation of the silver image on the said support, contacting the silver image with an organic mercaptan containing an oleophilic group in the molecule which is 10 capable of rendering the silver image oleophilic, inking the silver image with greasy printing ink and printing therefrom in a lithographic printing press.
• a process for preparing a photographic image from an exposed silver halide emulsion layer comprising developing the emulsion layer, transferring the silver halide from the undeveloped areas of the emulsion layer to a support containing a silver precipitating agent in the presence of a silver halide solvent and directly following the formation of the silver image on the said support, contacting the silver image with a thio-acid containing an oleophilic group in the molecule which is capable of rendering the silver image oleophilic, inking the silver image with greasy printing ink and printing therefrom in a lithographic printing press.
• a process for preparing a photographic image from an exposed silver halide emulsion layer comprising developing the emulsion layer, transferring the silver halide from the undeveloped areas of the emulsion layer to a support containing a silver precipitating agent in the presence of a silver halide solvent and directly following the formation of the silver image on the said support, contacting the silver image with a thio-amide containing an oleophilic group in the molecule which is capable of rendering the silver image oleophilic, inking the silver image with greasy printing ink and printing therefrom in a lithographic printing press.
• a process for preparing a photographic image from an exposed silver halide emulsion layer comprising developing the emulsion layer, transferring the silver halide from the undeveloped areas of the emulsion layer to a support containing a silver precipitating agent in the presence of a silver halide solvent and directly following the formation of the silver image on the said support, contacting the silver image with an isothiocyanate containing an oleophilic group in the molecule which is capable of rendering the silver image oleophilic, inking the silver image with greasy printing ink and printing therefrom in a lithographic printing press.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Printing Plates And Materials Therefor (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)

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Citations (5)

• 0
  • BE BE582161D patent/BE582161A/xx unknown
  • BE BE582160D patent/BE582160A/xx unknown
• 1958
  • 1958-08-29 GB GB40344/59A patent/GB934694A/en not_active Expired
  • 1958-08-29 GB GB27799/58A patent/GB934691A/en not_active Expired
• 1959
  • 1959-06-05 GB GB19301/59A patent/GB934693A/en not_active Expired
  • 1959-06-05 GB GB19300/59A patent/GB934692A/en not_active Expired
  • 1959-08-21 FR FR803328A patent/FR1242943A/fr not_active Expired
  • 1959-08-21 FR FR803327A patent/FR1243430A/fr not_active Expired
  • 1959-08-26 US US836077A patent/US3161508A/en not_active Expired - Lifetime

Patent Citations (6)

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