CA1060695A - Photolithographic receptor base - Google Patents

Photolithographic receptor base

Info

Publication number
CA1060695A
CA1060695A CA232,879A CA232879A CA1060695A CA 1060695 A CA1060695 A CA 1060695A CA 232879 A CA232879 A CA 232879A CA 1060695 A CA1060695 A CA 1060695A
Authority
CA
Canada
Prior art keywords
solution
sheet
silver
plate
layer
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
Application number
CA232,879A
Other languages
French (fr)
Inventor
David R. Boston
Dallas K. Pierson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
3M Co
Original Assignee
Minnesota Mining and Manufacturing Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Minnesota Mining and Manufacturing Co filed Critical Minnesota Mining and Manufacturing Co
Application granted granted Critical
Publication of CA1060695A publication Critical patent/CA1060695A/en
Expired legal-status Critical Current

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Classifications

    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004Photosensitive materials
    • G03F7/06Silver salts
    • G03F7/07Silver salts used for diffusion transfer

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)
  • Printing Plates And Materials Therefor (AREA)
  • Manufacture Or Reproduction Of Printing Formes (AREA)
  • Manufacturing Of Printed Wiring (AREA)

Abstract

ABSTRACT
A photolithographic receptor base for silver salt diffusion transfer imaging comprising a substrate with a layer of hydrophilic colloidal silica containing silver precipitating nuclei thereon, the silica layer being formed from a mixture of two colloidal silica solutions of substantially uniform particle size, one having a particle size of about 2.5 times that of the other. The photolithographic base of the present invention has a longer useful life than those Known in the prior art. This is believed to be the result of forming the base from two colloidal silicas rather than the single colloidal silica of the prior art.

Description

. 1060695 FN 911,668 PHOTOLITHO~RAPHIC RECEPTOR BASE
. .
This invention relates to lithographic printin~
and more particularly, to a photolithographic image receptor sheet which can be imaged by utilization of silver salt dif~usion trans~er principles.
Procedures for preparlng photographic images of silver by diffusion transfer principles are generally well known in the art. Typically, an imagewise exposed silver halide emulsion is contacted with a processing compositlon containing a developing agent to reduce the exposed silver halide to silver in the emulsion and a sllver halide solvent capable of providing a soluble silver complex with the un-exposed silver halide. An imagewise distributlon of this silver complex is then transferred to a superposed silver-receptive stratum where it is reduced to metallic silver to impart thereto a ~ilver transfer image.
Dlf~usion transfer has been employed in connection with photolithography by utillzing a hydrophilic material as the silver receptive stratum (to thereby provide the background of a printing pla~e). The silver image is then used to generate an ink-receptive printing surface on the hydrophilic background. In such a system the hydrophilic background. In such a system, the hydrophilic silver-receptive ~tratum of the receptor sheet contains silver-precipitating nucl,ei di~persed in a microscopically continuous vehicle or matrix. One such matrix which has --~
been used is colloidal sllica, the silver belng deposited lmagewise on the sllica surface to provide the ink-recep-tive image areas of the plate.
Two-~old di~ficulties are presented by thls approach. First of all, a colloldal silica surface is , ,,, q~

106~695 generally not tough enough to withstand the pressures and abrasive forces exerted by the press rollers, limiting the plate in terms of press life. Secondly~ a sllica matrlx typically does not allow sufflcient silver deposition on the surface thereof to provide a durable ink-receptive image area capable of extended press runs.
One commercially successful photolithographic plate using the diffuslon transfer process~ disclosed in Ca,Yao/~
Assignee's copendin~ application Serial No. 940,565 filed September 14, 1965 in the name of Eikvar, alleviates a part of the aforementioned difficulties. Therein a sheet structure is disclosed comprising a base sheet having an organophilic surface over which is coated a liquid perme-able tough hydrophillc layer, e.g. silica, containing silver precipitating nuclei therein. Upon imaging by diffusion transfer, the hydrophilic layer is contacted with a solution whlch leaches the silver image from such layer. Upon swabbing and rinsing the plate, portions of ~ --the hydrophilic layer are also removed to reveal or expose the underlying organophilic ink-receptive surface in deslred image areas. Thus, Eikvar removes the problem of silver image breakdown by not utllizing the silver as his ink-receptive printing areas.
While Elkvar's plate exhibits numerous advantages over previously provided ~tructures, the difficulty with background breakdown when hydrophilic silica is utilized, remains.
The present invention provides a tough hydrophilic silica background capable of extended press runs and allows sufficient sllver deposition on the silica surface to provide a durable ink-receptive image ~rea.

106~)695 In accordance with the invention there is pro-vided a photolithographlc receptor base for imaging by the silver salt diffusion transfer process comprislng a support havlng a hydrophlllc colloldal sillca layer contalning silver precipitating nuclei thereon, said silica layer being ~ormed from a mixture of two colloidal silica solutions, each of a substantially uniform particle size, and wherein the particle size of one of the solutions is about 2.5 times greater than that of the other solution.
Thls serves to optimlze the amount of interparticle bonding and number of particles per unit volume in the silica lattice.
The hydrophllic silica matrix formed ls ldeal for preparing a silver-imaged lithographic plate since it `
insures optimum silver deposition at the surface thereof and it minimizes the tendency Or the silica particles to abrade a crush during press operatlon.
Utllizing this silica matrix a lithographic prlnting plate having extended press life compared to prior disclosed plates utilizing colloidal sillca as the hydrophilic base can be prepared.
The particles in a dry hydrophilic matrix of colloidal silica are spheroidal in shape and chemically bonded to one another at points where they touch. Although not wishing to be llmited by theory 3 it is bolivod that the silica lattice formed resembles a densely packed lattice array of spherical particles such as that commonly termed the "cubic close pack". In such a lattice array, a rela-tively large void is created between the touching particles, the diameter of the void being about 40 percent of the di-ameter of the particles of the lattice. This voidg when pro~ected throughout the matrix, produces a relatively porous lattice.

, .~ . . . .

~060695 In a silica matrix utilized as a diffusion transfer receptor, this would increase the tendency for silver to be deposited within the silica lattice as opposed to on the surface thereof and also lessen the resistance of the matrix particles to abraslon or crushing.
In an extended lattice, the number of large voids should equal the number of particles within the lattice.
If each such large void is filled with a particle of the appropriate size, the porosity of the lattice should be substantially reduced because more particles are contained per unit volume. Additionally, the number of interparticle bonds in the lattice should double thereby greatly increas-ing the reslstance of the particles to abrasion or crushing.
While the foregoing is based on theory, it has been found that a colloidal silica matrix prepared in accordance with this theoretical approach provides an extremely effective photolithographic receptor base.
Thus, if a colloidal silica solution having a substantially unlform particle slze is mixed with a second colloidal silica solution having a substantially uniform particle size, the particle slze of the flrst being about
2.5 tlmes that of the second, a silica matrix can be formed havin~ excellent effectivenesc as a hydrophilic receptor base.
By substantially uniform particle size is meant that the smallest particles of the first solution are generally at least about 1.5 tlmes larger than the largest particles of the second solution.
Commerclally available colloidal silica solutions generally contain a range of partlcle sizes, e.g. 4 to 7 m~, 8 to 11 m~, 14 to 17 m~, 21 to 25 m~, etc. A preferred 106~695 ~4 mixture is Nalco 1030 which is a solution having sillca particles in the size range of 14 to 17 m~, and Nalco 2195, which is a solution having silica particles in the slze range of 4 to 7 m~.
In theory, an extended lattice should produce a large void for every particle. Therefore, the optlmum particle ratio of small particles to large particles should be 1 to 1. However, silica particles are only spheroidal and not spherical, and the solution particle sizes are only substantially uniform and not absolute.
Accordingly, it has been found that a particle ratio of small to large particles of from about 0.5 to 1 to about 4 to 1 will provide a suitable photolithographlc surface with about o.8 to 1 to about 2tO to 1 being preferred. -~
As the ratio decreases, the effectiveness of the silica -~
surface is reduced because the particle density, i.e. the number of particles, per unit volume decreases. As the ratio increases, while the particle density per unit volume increases, the smaller particles apparently migrate to the silica surface and thereby cause a reduction in ad-hesion of reduced silver to the surface.
Conventional substrates sùch as polyesters or metals can be utilized as the plate backing in my invention.
The substrate typically can be coated initially with adhesion promoters, e.g. vinly chloride-acetate~ prior to application of the sillca layer thereto.
My inven~ion will now be more specifically described with the aid of the following non-limiting examples, whereln all parts are by weight unless otherwise specified.

t~ad~r~ 5 ~060695 Example 1 A support sheet composed of 4 mil (100 micron) polyethylene terephthalate film is coated on one surface ,~
with an 8-micron thick dr~ layer from a solution containing 48 percent solids by weight of Union Carbide's Vinylite VAGH vinyl chlorlde-acetate resin and American Cyanamide's Unitane OR 350 (tltanium dioxide) pigment in a ratio of
3 parts titanlum dloxlde to 1 part by weight of resin.
The pigment previously had been dispersed in the solution by ball mllling for 48 hours and the pigmented solution in methyl ethyl ketone solvent was coated on the support sheet and dried at 150F for 5 minutes.
The coated support sheet is overcoated with a hydrophlllc slllca layer of the followlng composltion, followed by drying for 20 seconds at 150F.
Ingredient Amount .
"Nalco 1030" colloidal sllica solution (having a particle size range o~ 14 to 17 m~) 227 grams "Nalco 2195'l colloidal silica solution (having a particle size range of 4 to 7 m~) 11.9 grams Merck's Silver Protein Mild at 10 percent solids in water 4.5 milliliters ;-~lycerin 1.1 grams - The gl,ycerin, whlle not necessary in the slllca layer, improves shelf~ e stability of the receptor element.
After allowing the coated sheet to cure for 25 days at ambient conditions, a high contrast chlorbromlde photographlc emulsion (e.g. one having a chloride/bromide ratio of 2:1 and a gelatln/silver ratio o~ 1.2:1) is coated over the hydrophillc sllica layer at a silver coating ' weight of 20 milligrams per square decimeter.

* tr~ rK -6-~06~)695 A 10-inch by 15-inch sheet of the above material was placed in the exposure unit o~ a Minnesota Mining and .l Manu~acturing Brand 412 Camera Plate Processor and exposed imagewise to a target. The sheet was then photographically 5 developed with a diffusion transfer developer having the following composition.
In~redient Amount deionized water 1,000 milliliters sodium sul~ite 80 grams hydroquinone 35 grams sodium thiosulfate 15 grams sodium hydroxlde 28.5 grams potassium bromide 2.5 grams 0.5 percent benzotriazole in water 25 milllliters After washing the emulsion o~f' with warm water, a positlve, rlght-readlng copy of the original is obtained, characterized by the imagewise formation o~ dense, continuous sllver masses havlng a mlrror-llke metalllc appearance on the sillca layer sur~ace.
The copy ls then lmmersed for 25 seconds at room temperature ln a solution of the ~ollowing composltlon:
In~redient Amount Potasslum Ferrocyanide 33.0 grams Sodlum Chloride 17.5 grams 2-Benzyl-2-lmidazoline hydrochloride 10 grams Delonlzed water (in amount suf~icient to make one liter of solution) This material conditions the silver image areas so as to be lithographically functional, i.e. ink receptive.
A~ter washing the sheet material ~or 10 seconds and drying, ~ ~raJe /no.rk ~0160695 the sheet was mounted onto an ATF Chief 15 printlng press whereupon 8000 good quallty copies were prepared with no deterioratlon in image quality.
Example ?
A printing plate was prepared as per Example 1 5 with the exception that the following colloidal sllica solutlon was utilized:
Ingredi _ Amount Nalco 1030 815 grams Nalco 2195 41.5 grams Merck's Silver Proteln Mild 25.2 milliliters Glycerine 15.6 grams Deionized water 153.5 grams The plate was processed as per Example 1. Upon mounting on a press, about 5500 good ~uality copies were obtained.
When Example 2 is repeated utilizing only Nalco 1030 sillca in place o~ the mixture, only about 1500 copies were obtained prior to plate breakdown.
It will be understood that the present invent~on ls also appllcable to a two sheet structure whereln the photographic emulsion ls omitted from the plate and carried by a separate fllm carrler, e.g., a conventlonal photographic fllm. The latent lmage can thus be ~ormed by exposure of the . ..... .
photographlc fllm, the ~ilm then placed in intimate contact 25 with the hydrophllic layers of Examples 1 and 2, and developed utilizing the developer of Example 1. Following development the two sheets can be peeled apart, e~fectuating a silver image on the hydrophllic surface.

~ ~r~JeJh~.r~

Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A photolithographic receptor sheet for imaging by a silver salt diffusion transfer process comprising a support having coated thereon a hydrophilic colloidal silica layer containing therein silver precipitating nuclei, said layer having been formed from a mixture of first and second colloidal silica solutions, each of said solutions having substantially uniform particle sizes, and wherein the particle size of said first solution is about 2.5 times greater than the particle size of said second solution.
2. The sheet of claim 1 wherein the concentration of said solutions is such that the ratio of particles of said second solution to said first solution is from about 0.5 to 1 to about 4.0 to 1.
3. The sheet of claim 2 wherein said ratio is 1.0 to 1.
4. The sheet of claim 1 wherein said support is polyester.
5. The sheet of claim 1 further comprising an adhesion promoting layer interposed between said support and said silica layer.
6. The sheet of claim 5 wherein said adhesion promoting layer comprises a vinyl chloride-acetate resin and titanium dioxide.
7. A lithographic plate having image areas and background areas comprising a support having coated thereon a hydrophilic colloidal silica layer said silica layer having silver deposited thereon by means of a diffusion transfer process to thereby form said image areas, said silica layer having been formed from a mixture of first and second colloidal silica solutions, each of said solutions having substantially uniform particle sizes, and wherein the particle size of said first solution is about 2.5 times greater than the particle size of said second solution.
8. The plate of claim 7 wherein the concen-tration of said solutions is such that the ratio of par-ticles of said second solution to said first solution is from about 0.5 to 1 to about 4.0 to 1.
9. The plate of claim 8 wherein said ratio is 1.0 to 1.
10. The plate of claim 7 wherein said support is polyester.
11. The plate of claim 7 further comprising an adhesion promoting layer interposed between said support and said silica layer.
12. The plate of claim 11 wherein said adhesion promoting layer comprises a vinyl chloride-acetate resin and titanium dioxide.
CA232,879A 1974-09-09 1975-08-05 Photolithographic receptor base Expired CA1060695A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US50424474A 1974-09-09 1974-09-09

Publications (1)

Publication Number Publication Date
CA1060695A true CA1060695A (en) 1979-08-21

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Country Status (13)

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JP (1) JPS5156303A (en)
AR (1) AR207598A1 (en)
AU (1) AU8462175A (en)
BE (1) BE833183A (en)
CA (1) CA1060695A (en)
CH (1) CH616886A5 (en)
DD (1) DD121200A5 (en)
DE (1) DE2540319C3 (en)
FR (1) FR2284138A1 (en)
GB (1) GB1502649A (en)
IT (1) IT1044674B (en)
SU (1) SU631060A3 (en)
YU (1) YU226775A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2813495A1 (en) * 1977-03-28 1978-10-05 Minnesota Mining & Mfg PHOTOLITHOGRAPHIC RECEIVING SHEET

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1004080A (en) * 1972-01-07 1977-01-25 Eastman Kodak Company Lithographic material
JPS5115764B2 (en) * 1972-04-05 1976-05-19

Also Published As

Publication number Publication date
DE2540319B2 (en) 1981-06-11
IT1044674B (en) 1980-04-21
DE2540319A1 (en) 1976-03-18
SU631060A3 (en) 1978-10-30
FR2284138B1 (en) 1981-08-21
AR207598A1 (en) 1976-10-15
GB1502649A (en) 1978-03-01
BE833183A (en) 1976-03-08
FR2284138A1 (en) 1976-04-02
JPS5644428B2 (en) 1981-10-19
JPS5156303A (en) 1976-05-18
DD121200A5 (en) 1976-07-12
DE2540319C3 (en) 1982-03-18
CH616886A5 (en) 1980-04-30
AU8462175A (en) 1977-03-17
YU226775A (en) 1982-05-31

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