CA1199217A - Offset printing form and method of making it - Google Patents
Offset printing form and method of making itInfo
- Publication number
- CA1199217A CA1199217A CA000423104A CA423104A CA1199217A CA 1199217 A CA1199217 A CA 1199217A CA 000423104 A CA000423104 A CA 000423104A CA 423104 A CA423104 A CA 423104A CA 1199217 A CA1199217 A CA 1199217A
- Authority
- CA
- Canada
- Prior art keywords
- layer
- resist
- photoresist
- offset printing
- printing form
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
- B41C1/00—Forme preparation
- B41C1/10—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
- B41C1/1008—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials
- B41C1/1033—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials by laser or spark ablation
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Thermal Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Printing Plates And Materials Therefor (AREA)
- Photosensitive Polymer And Photoresist Processing (AREA)
Abstract
OFFSET PRINTING FORM AND METHOD OF MAKING IT
Abstract The offset printing form comprises a metal foil (1) rendered oleophobic and a superimposed micro-rough layer (2) in the form of the pattern to be printed, consisting of a resist filled with e.g. soot, possibly a thin metal layer (3) applied onto the resist layer (2), and a top layer (4) of photoresist.
For making the offset printing form, a record carrier consisting of a metal foil (1) rendered oleophobic, a superimposed micro-rough resist layer (2) filled e.g. with soot, and a superimposed thin metal layer (3) with an inscribed pattern corresponding to the pattern to be printed, is blanket deposited with a layer (4) of a pho-toresist which is subsequently blanket irradiated, the radiation being reflected several times where the photo-resist layer (4) lies on the metal layer (3), between the interface photoresist-aluminum and photoresist-air, and being subsequently developed. Simultaneously with development, or subsequently, exposed regions of metal layer (3) are removed, and finally the exposed regions of resist layer (2) are removed.
Abstract The offset printing form comprises a metal foil (1) rendered oleophobic and a superimposed micro-rough layer (2) in the form of the pattern to be printed, consisting of a resist filled with e.g. soot, possibly a thin metal layer (3) applied onto the resist layer (2), and a top layer (4) of photoresist.
For making the offset printing form, a record carrier consisting of a metal foil (1) rendered oleophobic, a superimposed micro-rough resist layer (2) filled e.g. with soot, and a superimposed thin metal layer (3) with an inscribed pattern corresponding to the pattern to be printed, is blanket deposited with a layer (4) of a pho-toresist which is subsequently blanket irradiated, the radiation being reflected several times where the photo-resist layer (4) lies on the metal layer (3), between the interface photoresist-aluminum and photoresist-air, and being subsequently developed. Simultaneously with development, or subsequently, exposed regions of metal layer (3) are removed, and finally the exposed regions of resist layer (2) are removed.
Description
2~.~
The invention relates to an offset printing form comprising a metal foil and a photoresist layer placed thereupon, in the form of the pattern to be printed, and a method of making an offset printing form from a record carrier inscribed with an electro-erosion printer.
Usually, such record carriers for electro-erosion printers, hereinafter called record carriers, consist o~ a thin metal film applied on a substrate. At least that substrate portion which is adjacent to the metal film is non--conductive. An offset printing form is a flat printing form where the image-wise differentiation is effected in practically one plane, and implemented chemophysically through oleophilic and o:Leophobic areas on the printing ; form. An offset printing form consists of at least two layers, i.e. a mechanicallv stable carrier foil and a thin layer thereupon which has a design corresponding to the pattern to be printed. The exposed surface of the substrate which in the present case consists, e.g., of aluminum is preferably oleophobic, and the layer material which in the present case consists of a resin layer is oleophilic, i.e.
ink-attractive. However, there also exist offset printing forms where the carrier ma-terial which in that case consists, e.g~, of a synthetic foil is oleophilicl whereas the surface of the layer which in that case preferably consists of aluminum represents the oleophobic areas.
There already exist offset printing forms made of record carriers. The production of such offset printing forms is GE9-81~018 l described e.g. in DE-AS l 496 152, and DE-OS 24 59 055, 25 14 682, and 24 33 448. The thus made offset printing forms are each of the type which is used less frequently where the carrier foil is oleophilic and the applied layer, e.g. an aluminum layer is oleophobic. The offset printing forms made in accordance with prior art are available either after printing, or after a protective layer covering e.g. the aluminum has been removed during printing. Furthermore, high resolution patterns cannot be transferred by means of electro-erosion printers onto the record carriers used there. This is due to the fact that the layer or layers to be printed on have to be relatively thick to make sure that the offset printing form is suEficiently stable from a mechanical point of view.
A record carrier without these disadvantages is structured of a metal foil carrying a layer only as few ~m thick which consists of a high impedance, light-absorbing resist and which is of a defined micro-roughness. Onto this resist, a very thin mekal layer is vapor-deposited. In that connection, "thin" means less than lOO nm, and "high impedance" means greater than lOO MQ/ ~ . When this record carrier is inscribed, current is guided through the thin aluminum layer by means of a stylus; a light arc forming at the point of contact after the aluminum has melted there, that light arc effecting the evaporation of the melted aluminum. Owing to the above mentioned roughness in combination with the small thickness of the metal layer to be inscrihed, highly resolved patterns can be transferred onto the record carrier~ Attempts have been made to use the above mentioned record carrier after printing directly as an offset printing form. However, it has turned out that the 1 highly oleophobic qualities of the aluminum, together with the highly oleGphilic characteristics of the resist could not be reached. This wettability difference would have been the prerequisite for using the above mentioned record carrier as an offset printing form. Furthermore, the inscribed record carrier did not have the mechanical stabl-lity needed for an offset printing formD
It is the object of the invention to provide an o:Efset printing form that can be made of a record carrier which is inscribed by means of an electro-erosion printer, and which has a micro-rough, high impedance, light-absorbing .resist deposited on a metal carrier foil and a thin metal layer vapor deposited on said resist, as well as a method of making such an offset foil of the above menti.oned record carrier.
This object is achieved with an o~fset printing form of the type and method specifie~ below a.nd in the claims~
Offset printing forrns according to the preamble of patent claim 1 are known e.g~ from the article "Neue Technologien zur filmlosen Herstellung von Druckformen" (New technologies for the film-less making of printing forms~ by H.W. Vollmann, published in Angewandte Chemie, 92, pp~95ff~(1980)o Such offset printing forms are made from an original transparent photographic image is made through which a photoresist layer prQvided on an aluminum foil is e~posed and subsequenily developed, with the offset printing form being obtained as a result~ In this manner, it is also possible to make an offset printing form of a pattern 30- inscribed by means of an electro erosion printer in a record carrier. The generation of the offse~ printing form in G~9 81-018 3 2~L7 1 accordance with the invention ho~ever does not require the production of a transparent photographically made original, nor the photolithographic transfer of the pattern made thereon into a photoresist layer. In fact, -the offset printing form as disclosed by the invention can be made directly from the record carrier inscribed by the electro-erosion printer, and of the kind defined with the object of the present invention, involving only a very small amount of time and apparatus. Contrary to the offset printing forms produced through the direct inscribing in the record carrier, in accordance with the above mentioned prior art, the offset printing form as disclosed by the invention is mechanically stable, and patterns of ~ery high resolution can be transferred thereby.
The method of making the of~set printing ~orm in accordance with the invention has been developed on the hasis of the surprising fact that in a uniform blanket exposure of a photoresist layer those areas on this layer which are on a micro-rough, reflecting surface are exposed to a radiation dose greater than twice that of those areas of the photoresist layer that are provided on a non-reflecting surface. If the photoresist layer is exposed to a radiation dosage of only about one third of that specified per se for the photoresist selected for a predetermined layer thickness, the differences of radiation intensity to which the individual photoresist areas will have ~een exposed is sufficient to ensure that during development the photoresist (with a positive resist being assumed for the present case) will remain over the ;
. G~9-81~018 4 1 non-reflectin~ substrate, and will be removed over the reflecting substrate.
A record carrier which is structured of a metal foil carrier, a superimposed soot-filled resist layer with a micro-rough surface, and a thin metal layer vapor deposited thereon, also havin~ micro-rou~hness, shows (after havin~
been inscribed by means of the electro- erosion printer, with the thin metal layer beiny selectively removed) micro-rough reflecting surface portions where the thin metal layer still exists, as well as non-reflecting surface areas where the metal layer has been removed. If therefore such a record carrier is coated with a photoresist layer, and subsequently exposed to a uniform blanket radiation it is possible, provided the procedures are executed as speclfied above, to generate in the photoresist layer a pattern which corresponds to the pattern inscribed by means of the electro~erosion printer. If in addition thereto it is made sure that those area~ of the thin metal layer and of the soot-filled layer which are not covered by the pattern in the photoresist are removed, the finished offset printing form in accordance with the invention is available, provided the metal carrier foil has been rendered oleophobic prior to the coating with the soo$ filled resist. It is pointed out in this connection that although micro-roughness increases the differences in radiation intensity it is not exclusively responsible therefor, iOe. there would be radiation differences in the above used record carriers with inscribed patterns a~so in those cases where the thin metal layer is completely smooth. It is true that the radiation differences would be smaller than if there were no 1 mlcro-rough metal layer~ but if a suitable photoresist and process conditions are selected :it should suffice for effecting useful differences in developing speed.
Advantageous embodiments of the offset printing form of the method of making them in accordance with the invention ; are described below.
The invention will be described with reference to drawings illustrating embodiments in accordance with the invention. Figs. 1 to 4 illustra~e in schematic cxoss-section the offset pri.nting form in accordance with the invention, in sequential stages of its manufacture, an inscribed record carrier.
In the following, the production of the offset printing form as disclosed by the ;.nvention will be described in detail, with reference to Fiys. 1 to 4.
Fig. 1 shows in a schematic cross-section the record carrier of which the offset printing form in accordance with the invention is made. The record carrier consists of a metal carrier foil 1 onto which is applied a layer 2 of a soot-filled resist, i.e. a resist which preferably contains a filler consisting of soot and if necessary calcium car-bonate. Onto layer 2, a thin metal layer 3 is vapor de-posited~ Metal carrier foil 1 consists preferably of aluminum, but other metals are suitable, too, which can be rendered oleophobic. Aluminum can be rendered oleophobic, or example, by means of anodizing. Metal carrler foil 1 is between O.l and 0O3 mm thicko Onto metal carrier foil 1 for GEg~81-018 6 2~
1 instance onto a foil of anodi~ed aluminum the soot-filled resist layer is applied which on an average is approximately 2 ~m thick. The resist material used is taken preferably from the group containing cellulose nitrate, cellulose butyrate, e.g. an acetomonobutyrateO As a plasticizer the resist preferably contains phthalic acid esters in quanti ties between approxi~ately 8 percent and 30 percent by weight of the resist portion. The soot portion in the resist is approximately less than 15 percent by weight of the resist portion. The size of the primary soot grains is approximately 0.05 ~m, and that of the secondary grains bet-ween approximately 2 and approximately 8 ~m. The secondary soot grains effect a micro-roughness of the resist layer in the order of approximately 5 ~m. The resist is deposited in that a dispersi.on of the components of resist layer 2 in an organic solvent, as e.g. ethyl acetate, with a solids content between approximately 20 and approximately 25 percent by weight i.s applied onto metal foil 1, and in that ; subsequently the solvent is evaporated. Thin metal layer 3 which preferably consists of aluminum and is approximately 30 nm thick, is vapor deposited onto dried resist layer 2.
Metal layer 3 is of approximately the same roughness as resist layer 2. The roughness of metal layer 3 ls necessary for inscribing the record carrier with the electro-erosion printer, and it is of advantage in the production of the offset printing form.
Fig. 1 depicts a structure after having been inscribed, i.e., after part of aluminum layer 3 has been selectively removed. Inscrlbing can be effected by means of the electro-erosion printer in such a manner that the portion to G~9-81 018 7 l be inscribed is contacted with a stylus, and that subse-quently there flows a current through the stylus and metal layer 3 which melts the metal at the spo-~ to be inscribed, so that an arc is formed which causes the evaporation of the melted metal. A contributory factor for the forming of the arc is the above discussed micro-roughness of metal layer 3 - t.he micro-roughness effects very high local field intensities.
In the next process step, a photoresist 4 is applied onto the structure of Fig. 1, e.g. by spraying or immersion. Since usually the pattern inscribed in the aluminum layer is to be transferred later with the offset printing form, the photoresist will generally be a positive : resist. However, it is also possible to transfer with the offset printing form the negative of the inscribed pattern, i.e. where the pattern inscribed in aluminum layer 3 is not dyed on the printed pages. In those cases a negative resist is used. In the following specification it is assumed that the photoresist used is a positive resist. Photoresist layer 4 is between approximately 1 and approximately 5 ~m thiclc. The thickness of photoresist layer 4 is substantially determined by the solubility of the exposed photoresist in the solvent for soot-filled resist layer 2.
Photoresist layer 4 is dried at temperatures of less than approximately 150C, and subsequently exposed. The blanket exposure preferably carried out with a broad band tungsten .~ lamp takes approximately 2 to approximately 5 minutes. The process involved is the following: Photoresist layer 4 over ;~ 30 those regions where aluminum layer 3 has been removed during . inscribing, i.s traversed by light and subsequently the :`
l radiation is completely absorbed in soot-filled resist layer 2~ i.e. these por-tions of photoresist layer 4 are traversed by radiation only once. However, where under photoresist layer 4 ther~ is still aluminum layer 3, the radiation is reflected, after having passed -through photoresist layer 4 at the surface of aluminum layer 3. Owing to the micro~roughness of aluminum layer 3, the radiation is reflected in very different directions and also causes total reflections on the one hand at the interface between photoresist and aluminum layer 3, and on the other a-t the interface between the photoresist and air. The effect of the above mentioned ref].ection of the radiation is that in those areas of photoresist ~ which are based on aluminum layer 3 a beam tra~erses photoresist layer 4 in its entire thickness at least two to three times on an averaye, with the consequence that those pho-toresist reyions which are based on aluminum layer 3 are irradiated with a hi.gher intensity than the re~ions placed directly on soot-filled resist layer 2.
~0 If in the next process step the structure obtained after irradiation and depicted in Fig. 2 is exposed to a developer suitable for the photoresist, the different effective intensity with which the individual regions of photoresist layer 4 have been irradiated suffices to permit complet~ removal of the photoresist ~here aluminum layer 3 s-till exists, whereas in those regions where the photoresist is placed on soot-~illed resist layer 2 d.irectly, photoresist layer 4 is not removed or to a very small extent only. Since the usual developers of the most fre~uently used positive resists ~polymers of the phenoiic resins of G~9-81-01~ 9 l the Novolak-type) are buffered a~ueous-alkaline solutions, aluminum layer 3 is completely removed, too, during developing. Fig~ 3 depicts in a schematic cross~section the structure ob~ained after developing. The areas of photoresist layer 4 which are left untouched by development reproduce the pattern inscrib~d by the electro-erosion printer in the record carrier, or in metal layer 3, respectively.
rrhe next process step removes those areas of soot-filled resist layer 2 which are not covered by photoresist layer 4. Depending on the resist used, a more or less concentrated acetic acid is employed. To give an example: For a cellulose nitrate resist ace-tic acid of over 80 percent concentration is used, for a resist on the cellulose acetomonobutyrate basis an acetic acid of approximately 50 percent to 60 percent concentration is used, and for a resist which contains cellulose butyrate as resist material which is marketed by Chicago Molted Products under the model designation B-120 an acetic acid of 30 percent is used. The removal of resist layer 2 takes between approximately 3 to 5 minutes. Fiy. 4 shows in a schematic cross section the structure thus obtained which represents a finished offset printing form in accordance with one aspect of th~ invention. In the following, the invention will be described in more detail with reference to a specific example.
.~
This example is based on an inscribed record carrier which consists of a 0.2 mm thick anodized aluminum foil~ a superimposed micro-rough~ soot filled resist layer 2 with an GE9~81-018 10 1 average thickness of approximately 2)um which contains as resist material the above mentioned cellulose butyrate marketed by Chicago Molted Products under the model designa-tion B-120, and as a plasticizer phthalic acid esters and a filler in the form of calcium carbonate and soot, the phthalic acid ester and the filler being provided in a quantity of approximately 20 percent by weight of the resist material portion, and oE an approximately 30 nm thick aluminum layer 3 vapor deposited onto resist layer 2. By means of blanket spraying onto layer 3 or ~, respectively, the record carrier is coated with an approximately 2 ~m thick layer 4, which consists of a phenolformaldehyde resin of the Novolak type, a positive resist which contains a diazonaphthoquinone as a sensitizer. A photoresist of the above rnentioned type is marketed e.g. hy Shipley under the trade name 1350 H. The photoresist layer is dried at a temperature of less than 150C. Subsequently, photoresist layer 4 is blanket exposed with an 1000 Watt broad band tungsten lamp for 3 minutes approximately. The thus obtained structure is developed with a buffered aqueous-alkaline developer solution for several minutes, with the photoresist over layer 3 and subsequently layer 3 itself being removed. The resulting structure is processed for three to five minutes with 30 percen-t acetic acid to remove those areas of resist layer 2 which are not covered by photoresist layer 40 The thus obtained structure can be used as an offset printing form without any additional processing~ This offset printing form is characterized by a high mechanical stability, and by the fact that metal foil 1 and photoresist layer 4 differ distinctly with respect to their wettability with ink.
GE9-81~018 11
The invention relates to an offset printing form comprising a metal foil and a photoresist layer placed thereupon, in the form of the pattern to be printed, and a method of making an offset printing form from a record carrier inscribed with an electro-erosion printer.
Usually, such record carriers for electro-erosion printers, hereinafter called record carriers, consist o~ a thin metal film applied on a substrate. At least that substrate portion which is adjacent to the metal film is non--conductive. An offset printing form is a flat printing form where the image-wise differentiation is effected in practically one plane, and implemented chemophysically through oleophilic and o:Leophobic areas on the printing ; form. An offset printing form consists of at least two layers, i.e. a mechanicallv stable carrier foil and a thin layer thereupon which has a design corresponding to the pattern to be printed. The exposed surface of the substrate which in the present case consists, e.g., of aluminum is preferably oleophobic, and the layer material which in the present case consists of a resin layer is oleophilic, i.e.
ink-attractive. However, there also exist offset printing forms where the carrier ma-terial which in that case consists, e.g~, of a synthetic foil is oleophilicl whereas the surface of the layer which in that case preferably consists of aluminum represents the oleophobic areas.
There already exist offset printing forms made of record carriers. The production of such offset printing forms is GE9-81~018 l described e.g. in DE-AS l 496 152, and DE-OS 24 59 055, 25 14 682, and 24 33 448. The thus made offset printing forms are each of the type which is used less frequently where the carrier foil is oleophilic and the applied layer, e.g. an aluminum layer is oleophobic. The offset printing forms made in accordance with prior art are available either after printing, or after a protective layer covering e.g. the aluminum has been removed during printing. Furthermore, high resolution patterns cannot be transferred by means of electro-erosion printers onto the record carriers used there. This is due to the fact that the layer or layers to be printed on have to be relatively thick to make sure that the offset printing form is suEficiently stable from a mechanical point of view.
A record carrier without these disadvantages is structured of a metal foil carrying a layer only as few ~m thick which consists of a high impedance, light-absorbing resist and which is of a defined micro-roughness. Onto this resist, a very thin mekal layer is vapor-deposited. In that connection, "thin" means less than lOO nm, and "high impedance" means greater than lOO MQ/ ~ . When this record carrier is inscribed, current is guided through the thin aluminum layer by means of a stylus; a light arc forming at the point of contact after the aluminum has melted there, that light arc effecting the evaporation of the melted aluminum. Owing to the above mentioned roughness in combination with the small thickness of the metal layer to be inscrihed, highly resolved patterns can be transferred onto the record carrier~ Attempts have been made to use the above mentioned record carrier after printing directly as an offset printing form. However, it has turned out that the 1 highly oleophobic qualities of the aluminum, together with the highly oleGphilic characteristics of the resist could not be reached. This wettability difference would have been the prerequisite for using the above mentioned record carrier as an offset printing form. Furthermore, the inscribed record carrier did not have the mechanical stabl-lity needed for an offset printing formD
It is the object of the invention to provide an o:Efset printing form that can be made of a record carrier which is inscribed by means of an electro-erosion printer, and which has a micro-rough, high impedance, light-absorbing .resist deposited on a metal carrier foil and a thin metal layer vapor deposited on said resist, as well as a method of making such an offset foil of the above menti.oned record carrier.
This object is achieved with an o~fset printing form of the type and method specifie~ below a.nd in the claims~
Offset printing forrns according to the preamble of patent claim 1 are known e.g~ from the article "Neue Technologien zur filmlosen Herstellung von Druckformen" (New technologies for the film-less making of printing forms~ by H.W. Vollmann, published in Angewandte Chemie, 92, pp~95ff~(1980)o Such offset printing forms are made from an original transparent photographic image is made through which a photoresist layer prQvided on an aluminum foil is e~posed and subsequenily developed, with the offset printing form being obtained as a result~ In this manner, it is also possible to make an offset printing form of a pattern 30- inscribed by means of an electro erosion printer in a record carrier. The generation of the offse~ printing form in G~9 81-018 3 2~L7 1 accordance with the invention ho~ever does not require the production of a transparent photographically made original, nor the photolithographic transfer of the pattern made thereon into a photoresist layer. In fact, -the offset printing form as disclosed by the invention can be made directly from the record carrier inscribed by the electro-erosion printer, and of the kind defined with the object of the present invention, involving only a very small amount of time and apparatus. Contrary to the offset printing forms produced through the direct inscribing in the record carrier, in accordance with the above mentioned prior art, the offset printing form as disclosed by the invention is mechanically stable, and patterns of ~ery high resolution can be transferred thereby.
The method of making the of~set printing ~orm in accordance with the invention has been developed on the hasis of the surprising fact that in a uniform blanket exposure of a photoresist layer those areas on this layer which are on a micro-rough, reflecting surface are exposed to a radiation dose greater than twice that of those areas of the photoresist layer that are provided on a non-reflecting surface. If the photoresist layer is exposed to a radiation dosage of only about one third of that specified per se for the photoresist selected for a predetermined layer thickness, the differences of radiation intensity to which the individual photoresist areas will have ~een exposed is sufficient to ensure that during development the photoresist (with a positive resist being assumed for the present case) will remain over the ;
. G~9-81~018 4 1 non-reflectin~ substrate, and will be removed over the reflecting substrate.
A record carrier which is structured of a metal foil carrier, a superimposed soot-filled resist layer with a micro-rough surface, and a thin metal layer vapor deposited thereon, also havin~ micro-rou~hness, shows (after havin~
been inscribed by means of the electro- erosion printer, with the thin metal layer beiny selectively removed) micro-rough reflecting surface portions where the thin metal layer still exists, as well as non-reflecting surface areas where the metal layer has been removed. If therefore such a record carrier is coated with a photoresist layer, and subsequently exposed to a uniform blanket radiation it is possible, provided the procedures are executed as speclfied above, to generate in the photoresist layer a pattern which corresponds to the pattern inscribed by means of the electro~erosion printer. If in addition thereto it is made sure that those area~ of the thin metal layer and of the soot-filled layer which are not covered by the pattern in the photoresist are removed, the finished offset printing form in accordance with the invention is available, provided the metal carrier foil has been rendered oleophobic prior to the coating with the soo$ filled resist. It is pointed out in this connection that although micro-roughness increases the differences in radiation intensity it is not exclusively responsible therefor, iOe. there would be radiation differences in the above used record carriers with inscribed patterns a~so in those cases where the thin metal layer is completely smooth. It is true that the radiation differences would be smaller than if there were no 1 mlcro-rough metal layer~ but if a suitable photoresist and process conditions are selected :it should suffice for effecting useful differences in developing speed.
Advantageous embodiments of the offset printing form of the method of making them in accordance with the invention ; are described below.
The invention will be described with reference to drawings illustrating embodiments in accordance with the invention. Figs. 1 to 4 illustra~e in schematic cxoss-section the offset pri.nting form in accordance with the invention, in sequential stages of its manufacture, an inscribed record carrier.
In the following, the production of the offset printing form as disclosed by the ;.nvention will be described in detail, with reference to Fiys. 1 to 4.
Fig. 1 shows in a schematic cross-section the record carrier of which the offset printing form in accordance with the invention is made. The record carrier consists of a metal carrier foil 1 onto which is applied a layer 2 of a soot-filled resist, i.e. a resist which preferably contains a filler consisting of soot and if necessary calcium car-bonate. Onto layer 2, a thin metal layer 3 is vapor de-posited~ Metal carrier foil 1 consists preferably of aluminum, but other metals are suitable, too, which can be rendered oleophobic. Aluminum can be rendered oleophobic, or example, by means of anodizing. Metal carrler foil 1 is between O.l and 0O3 mm thicko Onto metal carrier foil 1 for GEg~81-018 6 2~
1 instance onto a foil of anodi~ed aluminum the soot-filled resist layer is applied which on an average is approximately 2 ~m thick. The resist material used is taken preferably from the group containing cellulose nitrate, cellulose butyrate, e.g. an acetomonobutyrateO As a plasticizer the resist preferably contains phthalic acid esters in quanti ties between approxi~ately 8 percent and 30 percent by weight of the resist portion. The soot portion in the resist is approximately less than 15 percent by weight of the resist portion. The size of the primary soot grains is approximately 0.05 ~m, and that of the secondary grains bet-ween approximately 2 and approximately 8 ~m. The secondary soot grains effect a micro-roughness of the resist layer in the order of approximately 5 ~m. The resist is deposited in that a dispersi.on of the components of resist layer 2 in an organic solvent, as e.g. ethyl acetate, with a solids content between approximately 20 and approximately 25 percent by weight i.s applied onto metal foil 1, and in that ; subsequently the solvent is evaporated. Thin metal layer 3 which preferably consists of aluminum and is approximately 30 nm thick, is vapor deposited onto dried resist layer 2.
Metal layer 3 is of approximately the same roughness as resist layer 2. The roughness of metal layer 3 ls necessary for inscribing the record carrier with the electro-erosion printer, and it is of advantage in the production of the offset printing form.
Fig. 1 depicts a structure after having been inscribed, i.e., after part of aluminum layer 3 has been selectively removed. Inscrlbing can be effected by means of the electro-erosion printer in such a manner that the portion to G~9-81 018 7 l be inscribed is contacted with a stylus, and that subse-quently there flows a current through the stylus and metal layer 3 which melts the metal at the spo-~ to be inscribed, so that an arc is formed which causes the evaporation of the melted metal. A contributory factor for the forming of the arc is the above discussed micro-roughness of metal layer 3 - t.he micro-roughness effects very high local field intensities.
In the next process step, a photoresist 4 is applied onto the structure of Fig. 1, e.g. by spraying or immersion. Since usually the pattern inscribed in the aluminum layer is to be transferred later with the offset printing form, the photoresist will generally be a positive : resist. However, it is also possible to transfer with the offset printing form the negative of the inscribed pattern, i.e. where the pattern inscribed in aluminum layer 3 is not dyed on the printed pages. In those cases a negative resist is used. In the following specification it is assumed that the photoresist used is a positive resist. Photoresist layer 4 is between approximately 1 and approximately 5 ~m thiclc. The thickness of photoresist layer 4 is substantially determined by the solubility of the exposed photoresist in the solvent for soot-filled resist layer 2.
Photoresist layer 4 is dried at temperatures of less than approximately 150C, and subsequently exposed. The blanket exposure preferably carried out with a broad band tungsten .~ lamp takes approximately 2 to approximately 5 minutes. The process involved is the following: Photoresist layer 4 over ;~ 30 those regions where aluminum layer 3 has been removed during . inscribing, i.s traversed by light and subsequently the :`
l radiation is completely absorbed in soot-filled resist layer 2~ i.e. these por-tions of photoresist layer 4 are traversed by radiation only once. However, where under photoresist layer 4 ther~ is still aluminum layer 3, the radiation is reflected, after having passed -through photoresist layer 4 at the surface of aluminum layer 3. Owing to the micro~roughness of aluminum layer 3, the radiation is reflected in very different directions and also causes total reflections on the one hand at the interface between photoresist and aluminum layer 3, and on the other a-t the interface between the photoresist and air. The effect of the above mentioned ref].ection of the radiation is that in those areas of photoresist ~ which are based on aluminum layer 3 a beam tra~erses photoresist layer 4 in its entire thickness at least two to three times on an averaye, with the consequence that those pho-toresist reyions which are based on aluminum layer 3 are irradiated with a hi.gher intensity than the re~ions placed directly on soot-filled resist layer 2.
~0 If in the next process step the structure obtained after irradiation and depicted in Fig. 2 is exposed to a developer suitable for the photoresist, the different effective intensity with which the individual regions of photoresist layer 4 have been irradiated suffices to permit complet~ removal of the photoresist ~here aluminum layer 3 s-till exists, whereas in those regions where the photoresist is placed on soot-~illed resist layer 2 d.irectly, photoresist layer 4 is not removed or to a very small extent only. Since the usual developers of the most fre~uently used positive resists ~polymers of the phenoiic resins of G~9-81-01~ 9 l the Novolak-type) are buffered a~ueous-alkaline solutions, aluminum layer 3 is completely removed, too, during developing. Fig~ 3 depicts in a schematic cross~section the structure ob~ained after developing. The areas of photoresist layer 4 which are left untouched by development reproduce the pattern inscrib~d by the electro-erosion printer in the record carrier, or in metal layer 3, respectively.
rrhe next process step removes those areas of soot-filled resist layer 2 which are not covered by photoresist layer 4. Depending on the resist used, a more or less concentrated acetic acid is employed. To give an example: For a cellulose nitrate resist ace-tic acid of over 80 percent concentration is used, for a resist on the cellulose acetomonobutyrate basis an acetic acid of approximately 50 percent to 60 percent concentration is used, and for a resist which contains cellulose butyrate as resist material which is marketed by Chicago Molted Products under the model designation B-120 an acetic acid of 30 percent is used. The removal of resist layer 2 takes between approximately 3 to 5 minutes. Fiy. 4 shows in a schematic cross section the structure thus obtained which represents a finished offset printing form in accordance with one aspect of th~ invention. In the following, the invention will be described in more detail with reference to a specific example.
.~
This example is based on an inscribed record carrier which consists of a 0.2 mm thick anodized aluminum foil~ a superimposed micro-rough~ soot filled resist layer 2 with an GE9~81-018 10 1 average thickness of approximately 2)um which contains as resist material the above mentioned cellulose butyrate marketed by Chicago Molted Products under the model designa-tion B-120, and as a plasticizer phthalic acid esters and a filler in the form of calcium carbonate and soot, the phthalic acid ester and the filler being provided in a quantity of approximately 20 percent by weight of the resist material portion, and oE an approximately 30 nm thick aluminum layer 3 vapor deposited onto resist layer 2. By means of blanket spraying onto layer 3 or ~, respectively, the record carrier is coated with an approximately 2 ~m thick layer 4, which consists of a phenolformaldehyde resin of the Novolak type, a positive resist which contains a diazonaphthoquinone as a sensitizer. A photoresist of the above rnentioned type is marketed e.g. hy Shipley under the trade name 1350 H. The photoresist layer is dried at a temperature of less than 150C. Subsequently, photoresist layer 4 is blanket exposed with an 1000 Watt broad band tungsten lamp for 3 minutes approximately. The thus obtained structure is developed with a buffered aqueous-alkaline developer solution for several minutes, with the photoresist over layer 3 and subsequently layer 3 itself being removed. The resulting structure is processed for three to five minutes with 30 percen-t acetic acid to remove those areas of resist layer 2 which are not covered by photoresist layer 40 The thus obtained structure can be used as an offset printing form without any additional processing~ This offset printing form is characterized by a high mechanical stability, and by the fact that metal foil 1 and photoresist layer 4 differ distinctly with respect to their wettability with ink.
GE9-81~018 11
Claims (21)
1. Offset printing form comprising a metal carrier foil (1) rendered oleophobic; and a superimposed photoresist lay-er (4) in the form of the pattern to be printed, characterized in that between the metal foil (1) and the photoresist layer (4) a micro-rough layer (2) consisting of a high impedance, light absorbing resist and possibly a metal layer deposited on the light absorbing resist layer is provided
2. Offset printing form as claimed in claim 1, characterized in that the metal foil (1) is anodized.
3. Offset printing form as claimed in claim 1 or 2, characterized in that the metal foil (1) consists of aluminum, the resist material in the layer (2) of a material selected from the group containing cellulose butyrate and cellulose nitrate, and that the photoresist consists of positive or negative resist.
4. Offset printing form as claimed in claim 1 or 2, characterized in that the resist forming the layer (2) contains a filler, e.g. soot.
5. Offset printing form as claimed in claim 1 or 2, characterized in that the metal foil (1) is between approximately 0.1 and approximately 0.3 mm thick, the resist layer (2) is on an average approximately 2 µm thick, the thin metal layer (3) is approximately 30 µm thick, and the photoresist layer (4) between approximately 1 and approximately 5 µm thick.
6. Offset printing form as claimed in claim 1 or 2, characterized in that the micro-roughness of the resist layer (2) is in the µm range.
7. Method of making an offset printing form as claimed in claim 1, characterized in that a record carrier which consists of a metal foil (1) rendered oleophobic, of a superimposed, high impedance, light absorbing, and micro-rough resist layer (2), and of a superimposed thin metal layer (3) in which by means of an electro-erosion printer a pattern corresponding to the pattern to be printed is inscribed, is blanket coated with a layer (4) of a photoresist which subsequently is blanket irradiated and subsequently developed, that simultaneously with the development or subsequent to it the exposed areas of the metal layer (3), and finally the exposed areas of the resist layer (2) are removed.
8. Method as claimed in claim 7, characterized in that the thickness of the photoresist layer (4) is determined in the first place on the basis of its solubility in the solvent for the resist layer (2).
9. Method as claimed in claim 8, characterized in that in the presence of a resist layer (2) containing cellulose butyrate as a resist material, a 2 µm thick layer of a positive photoresist is applied, and that as a solvent for the photoresist layer a 30 percent acetic acid is used.
10. Method as claimed in any one of claims 7 to 9, characterized in that the photoresist layer is irradiated with a light quantity which is smaller by a factor of greater than 3 than it has been determined for the photoresist to produce an image on a smooth, non-reflecting background.
11. Method as claimed in any one of claims 8 to 9 characterized in that a record carrier which consists of an aluminum foil (1) rendered oleophobic, a superimposed high impedance, light absorbing, and micro-rough resist layer (2) which contains cellulose butyrate as a resist material, and which also consists of a superimposed approximately 30 nm thick aluminum layer (3) in which by means of an electro-erosion printer a pattern corresponding to the pattern to be printed has been inscribed, is blanket coated with an approximately 2 µm thick layer (4) of a positive resist which subsequently is blanket irradiated with a 1000 Watt tungsten broad band lamp, and subsequently developed, the still existing areas of the metal layer (3) being removed, and that finally the exposed areas of the resist layer (2) are removed with an approximately 30 percent acetic acid.
12. A structure for making an offset printing form comprising (a) a metal carrier foil, (b) a micro-rough layer of high impedance light absorbing resist; (c) a layer of photoresist superimposed on said high impedance light absorbing resist.
13. The structure of claim 12 further including a metal layer deposited on said high impedance light absorbing resist.
14. An offset printing form derived from the structure of claim 13 in which said metal layer deposited on said high impedance light absorbing resist has been retained in selected areas over said high impedance light absorbing resist.
15. An offset printing form of claim 14 wherein said photoresist has been removed from said selected areas over said metal layer.
16. An offset printing form of claim 15 wherein said metal layer is removed from said selected areas with or after said photoresist portions have been removed.
17. An offset printing form of claim 16 where said high impedance light absorbing resist has been removed from under said selected areas where said metal layer and photoresist have been removed.
18. A method of making a printing form useful for offset printing utilizing a record carrier structure including:
a metal carrier foil having superimposed high impedance light absorbing micro-rough resist layer and a thin metal layer covering said resist layer said method comprising (a) treating said structure by removing selected portions of said thin metal layer by electro erosion;
(b) coating said treated structure with a blanket coat layer photoresist;
(c) blanket irradiating said photoresist;
(d) developing said photoresist to remove desired portions of photoresist defined in relation to the remaining portions of the thin metal layer.
a metal carrier foil having superimposed high impedance light absorbing micro-rough resist layer and a thin metal layer covering said resist layer said method comprising (a) treating said structure by removing selected portions of said thin metal layer by electro erosion;
(b) coating said treated structure with a blanket coat layer photoresist;
(c) blanket irradiating said photoresist;
(d) developing said photoresist to remove desired portions of photoresist defined in relation to the remaining portions of the thin metal layer.
19. The method of claim 18 including removing the exposed areas of said metal layer simultaneously with or subsequently to development.
20. The method of claim 19 including removing exposed areas of said resist layer.
21. The method of any of claims 18 through 20 wherein said metal carrier foil is rendered oleophobic and said photoresist is oleophilic.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP19820101858 EP0088139B1 (en) | 1982-03-09 | 1982-03-09 | Lithographic printing plate and method for producing the same |
| EP82101858.7 | 1982-03-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1199217A true CA1199217A (en) | 1986-01-14 |
Family
ID=8188908
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000423104A Expired CA1199217A (en) | 1982-03-09 | 1983-03-08 | Offset printing form and method of making it |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0088139B1 (en) |
| JP (1) | JPH0247737B2 (en) |
| CA (1) | CA1199217A (en) |
| DE (1) | DE3275025D1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8703376D0 (en) * | 1987-02-13 | 1987-03-18 | Vickers Plc | Printing plate precursors |
| US4911075A (en) * | 1988-08-19 | 1990-03-27 | Presstek, Inc. | Lithographic plates made by spark discharges |
| CN110429029B (en) * | 2019-08-23 | 2022-02-18 | 合肥维信诺科技有限公司 | Photoresist pattern preparation method and array substrate preparation method |
| CN112259676B (en) * | 2020-10-19 | 2022-11-01 | 济南晶正电子科技有限公司 | Film bonding body with pattern, preparation method and electronic device |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2214934B1 (en) * | 1973-01-18 | 1978-03-24 | Thomson Csf | |
| GB1480081A (en) * | 1973-09-18 | 1977-07-20 | Ricoh Kk | Methods of producing printing masters by spark-recording |
| GB1451378A (en) * | 1973-12-13 | 1976-09-29 | Vickers Ltd | Lithographic printing blanks and their inscription |
| GB1490732A (en) * | 1974-04-05 | 1977-11-02 | Vickers Ltd | Electro-responsive printing blanks and their inscription |
| CA1144418A (en) * | 1979-12-17 | 1983-04-12 | Ari Aviram | Erosion process for generation of offset masters |
-
1982
- 1982-03-09 EP EP19820101858 patent/EP0088139B1/en not_active Expired
- 1982-03-09 DE DE8282101858T patent/DE3275025D1/en not_active Expired
- 1982-12-20 JP JP22219682A patent/JPH0247737B2/en not_active Expired - Lifetime
-
1983
- 1983-03-08 CA CA000423104A patent/CA1199217A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0088139B1 (en) | 1987-01-07 |
| DE3275025D1 (en) | 1987-02-12 |
| EP0088139A1 (en) | 1983-09-14 |
| JPH0247737B2 (en) | 1990-10-22 |
| JPS58153938A (en) | 1983-09-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0169049B1 (en) | Dye transfer image process | |
| EP0160396B1 (en) | Laser-imageable assembly and process for production thereof | |
| US4882245A (en) | Photoresist composition and printed circuit boards and packages made therewith | |
| US4034183A (en) | Process for the production of planographic printing forms by means of laser beams | |
| EP0684133B1 (en) | Lithographic printing members for use with laser irradiation imaging apparatus | |
| US4123279A (en) | Light-sensitive o-quinonediazide containing planographic printing plate | |
| CA2140462C (en) | Seamless offset lithographic printing members for use with laser-discharge imaging apparatus | |
| US2770534A (en) | Method and material for making overlay masks | |
| CA1051707A (en) | Photoresist film with non-photosensitive resist layer | |
| CA1096221A (en) | Manufacture of imaged articles by laser irradiation of a non-photo sensitive material | |
| WO1999011458A1 (en) | Thermal lithographic printing plates | |
| CA1088799A (en) | Metal image-forming material having an interlayer of aluminum/iron alloy | |
| US4183990A (en) | Step tablet | |
| CA1199217A (en) | Offset printing form and method of making it | |
| JPS55105560A (en) | Photoengraving by laser | |
| CA1289803C (en) | Photoresist composition and printed circuit boards and packages made therewith | |
| US6245477B1 (en) | Imagable compositions and printing forms | |
| EP0176693A2 (en) | Process for protecting vapor-deposited metal layers | |
| US2258956A (en) | Steel plate for lithographic printing | |
| EP0168179B1 (en) | Improvements relating to photolithography | |
| US4612270A (en) | Two-layer negative resist | |
| US4272604A (en) | Base plate and lithographic plate prepared by sensitization thereof | |
| GB1560325A (en) | Imaging film and method | |
| US6098544A (en) | Short run offset printing member | |
| US3856529A (en) | Method and materials for making half tone prints |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |