US3562119A - Presensitized aluminum photolithographic etched plate and elements and method used in the preparation of same - Google Patents

Presensitized aluminum photolithographic etched plate and elements and method used in the preparation of same Download PDF

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Publication number
US3562119A
US3562119A US586442A US3562119DA US3562119A US 3562119 A US3562119 A US 3562119A US 586442 A US586442 A US 586442A US 3562119D A US3562119D A US 3562119DA US 3562119 A US3562119 A US 3562119A
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plate
diazo
aluminum
light sensitive
lithographic
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US586442A
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English (en)
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John W Krueger
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Wisconsin Alumni Research Foundation
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Wisconsin Alumni Research Foundation
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    • 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
    • G03F7/016—Diazonium salts or compounds

Definitions

  • the stabilized surface is then provided with a coat ing of a water soluble, light sensitive resin forming diazo compound which, upon exposure, is reduced in the exposed areas to a resinous oleophilic, ink receptive compound which represents the ink receptive, water repellent image, while the diazo compound in the unexposed areas is removed by an aqueous wash, or preferably by the desensitizing solution to expose the underlying water receptive, lithographic surface which represents the nonimaged portions of the plate.
  • the ink receptive, water repellent imaging material forms on the surface of the plate in the exposed portions while the unexposed portions remain water receptive and hydrophilic.
  • the plate can be mounted on a conventional lithographic press for the production of multiple copies by conventional lithographic duplicating technique.
  • the number of copies that can be produced from plates of the type described is somewhat limited by the wear of the exposed image on the surface of the plate with the result that the imaged plate cannot be employed as a printing plate in the production of long run lithography.
  • the image formed on the surface of the plate is one characterized as having surface phenomenon, the amount of ink retained on the surface for transfer remains relatively constant in all of the exposed portions of the plate so that toned copies are incapable of being produced with presensitized plates of the type described.
  • FIG. 1 is a perspective view, partially in section, of a diazo sensitized aluminum lithographic plate prepared in accordance with the practice of this invention
  • FIG. 2 is a sectional elevational view of the arrangement of elements for exposure of the diazo sensitized aluminum lithographic plate of FIG. 1;
  • FIG. 3 is a schematic view of the arrangement of elements for electrical etch of the exposed plate of FIG. 2;
  • FIG. 4 is a perspective view, partially in section, of the etched lithographic plate produced in FIG. 3;
  • FIG. 5 is an enlarged perspective view, partially in section, of a modification in the etched lithographic plate of FIG. 4 in which the imaged portion is plated with an ink receptive, water repellent metal.
  • a number of unexpected phenomena, which amount to important discoveries, are involved in the fabrication of the diazo sensitized aluminum lithographic plate of this invention, including the capability of imaging from a negative by photographic means and the preparation of a deep etch lithographic imaged plate from the exposed plate whereby a photolithographic printing plate is made available for the printing industry.
  • an oxide of aluminum forms almost immediately on the surface of the aluminum plate and that the silicate treatment operates to bring about a reaction between the silicate and the aluminum oxide on the surface to form a hydrophilic layer of an aluminum oxidesilicon oxide which represents the lithographic surface and on which the light sensitive diazo resin compound is deposited with the aluminum oxide-silicon oxide layer functioning as a barrier to prevent decomposition or deterioration of the diazo compound applied to the surface thereof.
  • the diazo compound reacts with the nascent aluminum to form a stable diazo-aluminum compound in which the diazo compound retains its sensitivity to light and thus retains the properties required for producing an imaged master in response to exposure to a modulated light pattern corresponding to the image.
  • the described conditions for effecting a stable diazo-surface on the aluminum plate are effected by the incorporation of the diazo compound as an ingredient in a composition with which the surface of the aluminum plate is abraded or otherwise processed to effect removal of the oxide layer and to expose the raw aluminum to the diazo compound for stabilization or reaction.
  • the light sensitive diazo resin or resin forming compound is formulated as a component in combination with rose tripoli or other abradant which is stable to the diazo compound, such as silica dust, glass dust, pumice and the like, as represented by the following example.
  • the surface 14, after scouring, is not dried but is preferably washed with the diazo solution. If suitable precautions are taken, such as Working in an inert atmosphere or under an inert gas, the abraded aluminum can be washed with water before sensitizing. Although less desirable, the aluminum surface can be washed with water and sensitized before drying. In a preferred method, the abraded aluminum is protected from the oxygen in the air as much as possible. It is therefore contemplated to make use of antioxidants, such as thiourea during the process.
  • the rose tripoli in the above example can be replaced, in whole or in part, with other inert scouring agents such as pumice, silica dust and the like abrading materials which are inert to the diazo compound.
  • inert scouring agents such as pumice, silica dust and the like abrading materials which are inert to the diazo compound.
  • light sensitive diazo resins can be employed instead of the p-diazodiphenylamine sulfate-formaldehyde condensate of Example 1, such for example as aromatic azido resins and aliphatic azido resins or resins of the type described in the book entitled The Aromatic Diazo Compounds, by H. K. Saunders, 1949, published by Edward Arnold & Company of London (page 29); or monomolecular imino-quinone diazides; p-tertiary amino diazo resins are also useful, as well as the light sensitive diazo resins or resin forming compounds of the type described in the Jewett et al. Pat. No. 2,714,066. Also use can be made of the parent substance of the diazo resin such as the p-diazo phenylamine sulfate and preferably its formaldehyde reaction product.
  • the amount of light sensitive diazo resin in the diazo solution can be varied over a fairly wide limit, consistent with the ability to form a paste with the scouring material in which sufficient of the diazo resin is present for the combination with the aluminum as it is exposed.
  • concentration of the diazo resin in the solution can be varied up to as much as 25% but it is preferred to make use of between 0.25% to about 10% by weight of the solution and the ratio of the light sensitive diazo resin to the scouring medium can be varied over a fairly wide range such as within the range of one part by Weight of diazo resin to 250 parts by Weight of the rose tripoli or other scouring medium. It is preferred to work with a paste for efficient abrasion and continuous coverage with diazo solution. Thus additions of solution or abradient can be made from time to time.
  • the plate prepared in accordance with the preceding example is stabilized against the decomposition of the diazo resin compound so that additional amounts of diazo resin can be applied from solution onto the stabilized sur face, depending somewhat upon the use made of the plate.
  • the plate can be used as a presensitized photolithographic plate in the same manner as described in the aforementioned Jewett et al.
  • the exposed and developed plate can be mounted on a lithographic printing press for use in the production of a large number of copies of good quality.
  • the plate that is produced is one that is characterized by the formation of the image on the surface, as in the Jewett et al. patent, but in which the surface constitutes a base which differs from that of the silicated aluminum oxide of the aforementioned patent.
  • the adhesion of the image to the surface of the plate is outstanding.
  • diazo stabilized aluminum surface 14 it is desirable to incorporate a higher concentration of the light sensitive diazo resin in the scouring composition in order to deposit a higher concentration of diazo resin on the surface.
  • one or more additional layers 16 of diazo resin is deposited on the diazo stabilized aluminum surface 14.
  • the desired thickness of light sensitive diazo resin coating can be achieved by treatment of the diazo stabilized surface on the aluminum plate with a solution of the diazo resin in water and alcohol having a concentration within the range of about 1-10% by weight and preferably about 38% by Weight of the light sensitive diazo resin solids, as represented by the following example.
  • the solution can be flow coated or roller coated onto, the surface 14 of the diazo stabilized aluminum plate and then air dried or drying can be accelerated with hot air at an elevated temperature below the decomposition temperature for the diazo resin and preferably at a temperature of about 50 C.
  • the formed litho-etched plate can be stored in the dark for a relatively long period of time without deterioration of the light sensitivity of the plate.
  • tive transparency 18 is positioned on the sensitized surface of the aluminum plate and exposed to a carbon arc lamp 20 of 110 volts and 20 amps at a distance of 24 inches for about minutes.
  • a carbon arc lamp 20 of 110 volts and 20 amps at a distance of 24 inches for about minutes.
  • Other exposure techniques can be employed, as by exposure to xenon pulsed lamps and the like, and the exposure can be made through a negative transparency, positive transparency, or by direct exposure, using photographic technique.
  • the exposed plate is then subjected to an electrical etch in which the exposed plate 22 is immersed ,in the electrolyte 24 as the anode while use is made of a zinc rod or plate 26 at the cathode, as represented by the following example.
  • a surprising feature of this invention resides in the discovery that the electrical etch occurs through the light exposed oleophilic, hydrophilic layer rather than the unexposed hydrophilic areas to yield a deep etch well contaiuing the oleophilic image. To my knowledge this phenomenon has never heretofore been described nor even discussed as a possibility. This discovery has these consequences in the photomechanical imaging of metals. (1) All deep etch lithographic processes require that a positive original be used to produce a positive image; in contrast our deep etch process can use the negative directly from the camera and thus avoids the reversal step in the preparation of an original and the ordinary deep etch step in which large open areas must be staged. (2) All deep etch processes on single metal plates yield clear wells which must be made oleophilic wthout rendering unetched areas oleophilic; in contrast to this, our process can yield oleophilic wells.
  • the intensity of the current and the time of etch can be varied over fairly wide limits but in which the upper limit is defined by the time or intensity at which an etch begins to appear in the production of the plate surface underlying the unexposed portions of the plate.
  • the electrolyte When removed from the electrolytic cell, the electrolyte should be washed from the surface of the plate with alcohol, or less desirably with Water, for complete removal and for more rapid drying of the plate surface.
  • the surface of the plate may be then treated with a desensitizer of the type conventionally employed in lithographic duplication, such as the Addressograph-Multigraph desensitizer, with or without previous lacquering of the surface of the plate.
  • the desensitizer is applied preferably with rubbing with a cotton pad or the like to remove the diazo resin from the surface of the plate.
  • the plate may be inked or lacquered either before or after desensitizing, or the oleophilic image left after the etching step may be used as such.
  • the resulting plate is strongly hydrophobic in the etched portion 30 and hydrophilic in the unetched, non-imaged portions 32 of the plate.
  • the plate can be mounted on a conventional lithographic press for wetting sequentially by aqueous fountain solution, to wet out the non-imaged portions of the plate, and then by oleaginous ink, to wet out the etched imaged portions of the plate for transfer of the ink image from the plate to an offset blanket or directly to copy sheets.
  • the plate retains its image for the production of an endless number of copies and the plate can be reused any number of times, with periods of rest in between, Without deterioration of the image.
  • electrolytes can be employed for the electrolytic etch.
  • Such other electrolytes can be represented by aqueous solutions of salts such as sodium chloride, or combinations of sodium chloride and ammonium chloride, preferably in the ratio of 3 to 1, and present in concentrations to give a density of about 21 B.
  • the time of exposure to the electrolytic etch will depend somewhat upon the intensity of the current and concentration of the salts making up the electrolyte solution.
  • This invention contemplates the further improvement in the permanency of the image and in the ink receptivity of the image by flash printing to form a layer of copper and the like hydrophobic metal as a lining in the Wells formed by the etch. This can be accomplished, as by plating with a bath formed of an alkaline solution of copper sulfate, as represented by the following example.
  • EXAMPLE 4 9 grams ethanolamine 5.5 grams copper sulfate 300 cc. water 1% gum arabic or other brightener
  • the background corresponding to the unetched or nonimaged portions of the plate, will not be copper-plated while the walls of the wells formed by the deep etch will receive a thin copper coat which renders the imaged portions permanently hydrophobic.
  • the resulting plate constitutes an improved printing plate from which many hundreds of thousands of copies of good quality can be produced.
  • the light sensitive diazo resin is incorporated as a component in combination with the inert abradant to enable immediate stabilization by reacton or combination With the aluminum as it is freed by the abradant, a degree of stabilization sufficient for the production of a usable photolithographic plate can be achieved when the light sensitive diazo resin is applied for treatment of the aluminum surface independent of the abradant but substantially immediately following treatment of the surface to remove oxides normally formed on the surface, as by scouring with rose tripoli, pumice, silica, etc., wire brushing, rubbing as by kissing one surface with the other for selfabrasion, and the like.
  • the method for producing a diazo presensitized photolithgraphic printing plate comprising the steps of scouring the surface of the aluminum plate with a scouring composition containing the light sensitive, Water soluble diazo resin for combination with the aluminum as it is freed from interfering coatings.
  • the method of producing an imaged aluminum litho-etch printing plate comprising the steps of exposing the presensitized aluminum lithographic printing plate of claim 1 to a modulated light pattern, mounting the exposed plate as the anode in an electrolytic etch cell, passing a current through the cell whereby the portions of the aluminum underlying the exposed portions of the plate become etched, rinsing the surface of the etched plate to remove electrolyte, and then removing the layer containing the diazo resin from the surface of the etched plate to leave a surface having non-etched portions which define the hydrophilic, Water receptive, non-imaged areas 7 of the plate and second etched portions which define the ink receptive, hydrophobic imaged areas of the plate.
  • the method for producing a diazo presensitized photolithographic printing plate comprising the steps of abrading the surface of the aluminum plate to remove aluminum oxides from the surface and immediately following the abrading with a solution containing a water soluble, light sensitive diazo resin for combination with the exposed aluminum for stabilization thereof to form the light sensitive diazo stabilized aluminum surface.
  • the method for producing a diazo presensitized photolithographic printing plate having a diazo stabilized light sensitive aluminum surface which includes the step of coating the diazo stabilized aluminum surface with a solution of a water soluble, light sensitive diazo resin.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)
  • Manufacture Or Reproduction Of Printing Formes (AREA)
  • Printing Plates And Materials Therefor (AREA)
US586442A 1966-10-13 1966-10-13 Presensitized aluminum photolithographic etched plate and elements and method used in the preparation of same Expired - Lifetime US3562119A (en)

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BE (1) BE735076A (xx)
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4201821A (en) * 1978-12-22 1980-05-06 Howard A. Fromson Decorated anodized aluminum article
US4452877A (en) * 1982-08-26 1984-06-05 American Hoechst Corporation Electrolysis treatment of light sensitive diazo coated supports
CN107628666A (zh) * 2017-11-07 2018-01-26 北京工业大学 改性硅藻土负载纳米零价铁去除水中六价铬的方法

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4201821A (en) * 1978-12-22 1980-05-06 Howard A. Fromson Decorated anodized aluminum article
US4452877A (en) * 1982-08-26 1984-06-05 American Hoechst Corporation Electrolysis treatment of light sensitive diazo coated supports
CN107628666A (zh) * 2017-11-07 2018-01-26 北京工业大学 改性硅藻土负载纳米零价铁去除水中六价铬的方法

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GB1278293A (en) 1972-06-21
NL6908848A (xx) 1970-12-14
BE735076A (xx) 1969-12-01

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