CA1044512A - Process for the production of a light-sensitive offset printing plate - Google Patents
Process for the production of a light-sensitive offset printing plateInfo
- Publication number
- CA1044512A CA1044512A CA233,557A CA233557A CA1044512A CA 1044512 A CA1044512 A CA 1044512A CA 233557 A CA233557 A CA 233557A CA 1044512 A CA1044512 A CA 1044512A
- Authority
- CA
- Canada
- Prior art keywords
- coating
- screen
- light
- solvent
- dried
- 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
-
- 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
- G03F7/09—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers
- G03F7/115—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers having supports or layers with means for obtaining a screen effect or for obtaining better contact in vacuum printing
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Structural Engineering (AREA)
- 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)
Abstract
Abstract of the Disclosure In a process for the production of a light-sensitive offset printing plate suitable for the reproduction of halftones in which a light-sensitive coating in a sol-vent is applied to an opaque carrier and dried, a fine-meshed screen is pressed into the coating wet with solvent, and then removed from the coating, whereby relatively thick areas of the copying layer are pulled up by the meshes of the screen resulting in a structured surface of the light-sensitive coating. The screen may be pressed into the wet coating and removed therefrom before it is dried or after the coating is dried and then wetted and softened by a solvent. These offset printing plates are adapted for the reproduction of halftones without screening the light projected on its surface for image-wise exposure.
Description
~O~Sl~
PROCESS FOR II~E PRODUClION OF A LIGHT-SENSITrVE OFFSET PRINTING PLATE
The present invention relates to a process for the production of a light-sensitive offset printing plate from which a printing form may be obtained, without using a halftone screen in the copying of originals, which form reproduces the halftones with satisfactory gradation.
If halftone-images are to be produced in a satisfactory manner by means of a printing form which is produced photomechanically from a light-sensitive offset printing plate, usually a halftone screen is used for the exposure. The use of a halftone screen requires gPeat care and some exper-ience if the reproduction of halftones is to be satisfactory.
Therefore, it already has been proposed to impress a screen-like pattern upon the light-sensitive layer itself. In German Offenlegun~s~h~t No.
1,813,445 published in the name of applicant, Kalle AG.7 on June 25, 1970;
for example, a process is described in which the copying layer applied to the carrier of the copying layer has hollows the size of which is 1 to 50 at the surface of the copying layer and becomes smaller towards the bottom of the copying layer. It is relatively difficult to obtain apparatuses for carrying out the process in such a manner that the halftones are reproduced with good gradation, and it is also difficult to perform the process itself.
It is the object of the present invention to provide a process in ` which offset printing plates can be produced with relatively little expen-diture and having a surface structured in a manner suitable for producing printing forms which print halftones. It was attempted to achieve this ob-ject by proceeding from the above-mentioned process in which a fine pattern is produced on a light-sensitive layer on a carrier. The object is achieved ~; by a process in which during the application of the coating, a fine-meshed screen is pressed into the coating, -1- \,~
;' ~ .
, ~O~S12 while the coatlng is wet with solvent, and is then removed. The process preferably is performed in such a manner that the fine-meshed screen is pressed into the coating and removed before the coating is dried The fine-meshed screen used in the process may be composed of, for example, fine metal wires or plastic fibers, such as polyamide fibers or polyester fibers. Its mesh density preferably is between 20 and 200 meshes per cm. The thickness of the wires or fibers may, for example, be such that they cover about 60 to 80 per cent of the area of the screen fabric and the holes of the screen correspond to 20 to 40 per cent of the area of the screen fabric. However, the thickness of the wires or fibers has no essential influence on the desired effect accord-ing to the invention, i.e. the structuring of the light-sensitlve layer.-In the process, an opaque carrier for the copying layer is used, because otherwise light reflections from the back thereof might inter- ¦
fere with the exposure of the printing plate. Aluminum or zinc plates having a mechanically or electrochemically roughened surface are prefer-ably used. The solution used for the application of the coatlng to the carrier is one of the known copying solutions . It, for example, may contain ¦
a light-sensitive diazonium salt, a light-sensitive quinone diazide com-pound, a light-sensitive azido compound or a light-sensitive photo-polymer composition. The solvent forming one part of the solution thus may be water or an organic solvent containing water, if required.
, The process will now be further described, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a schematic view of one embodiment of the process, Figure la is a schematic view of another embodiment, Figure 2 is a schematic view of still another embodiment of the proces s, and
PROCESS FOR II~E PRODUClION OF A LIGHT-SENSITrVE OFFSET PRINTING PLATE
The present invention relates to a process for the production of a light-sensitive offset printing plate from which a printing form may be obtained, without using a halftone screen in the copying of originals, which form reproduces the halftones with satisfactory gradation.
If halftone-images are to be produced in a satisfactory manner by means of a printing form which is produced photomechanically from a light-sensitive offset printing plate, usually a halftone screen is used for the exposure. The use of a halftone screen requires gPeat care and some exper-ience if the reproduction of halftones is to be satisfactory.
Therefore, it already has been proposed to impress a screen-like pattern upon the light-sensitive layer itself. In German Offenlegun~s~h~t No.
1,813,445 published in the name of applicant, Kalle AG.7 on June 25, 1970;
for example, a process is described in which the copying layer applied to the carrier of the copying layer has hollows the size of which is 1 to 50 at the surface of the copying layer and becomes smaller towards the bottom of the copying layer. It is relatively difficult to obtain apparatuses for carrying out the process in such a manner that the halftones are reproduced with good gradation, and it is also difficult to perform the process itself.
It is the object of the present invention to provide a process in ` which offset printing plates can be produced with relatively little expen-diture and having a surface structured in a manner suitable for producing printing forms which print halftones. It was attempted to achieve this ob-ject by proceeding from the above-mentioned process in which a fine pattern is produced on a light-sensitive layer on a carrier. The object is achieved ~; by a process in which during the application of the coating, a fine-meshed screen is pressed into the coating, -1- \,~
;' ~ .
, ~O~S12 while the coatlng is wet with solvent, and is then removed. The process preferably is performed in such a manner that the fine-meshed screen is pressed into the coating and removed before the coating is dried The fine-meshed screen used in the process may be composed of, for example, fine metal wires or plastic fibers, such as polyamide fibers or polyester fibers. Its mesh density preferably is between 20 and 200 meshes per cm. The thickness of the wires or fibers may, for example, be such that they cover about 60 to 80 per cent of the area of the screen fabric and the holes of the screen correspond to 20 to 40 per cent of the area of the screen fabric. However, the thickness of the wires or fibers has no essential influence on the desired effect accord-ing to the invention, i.e. the structuring of the light-sensitlve layer.-In the process, an opaque carrier for the copying layer is used, because otherwise light reflections from the back thereof might inter- ¦
fere with the exposure of the printing plate. Aluminum or zinc plates having a mechanically or electrochemically roughened surface are prefer-ably used. The solution used for the application of the coatlng to the carrier is one of the known copying solutions . It, for example, may contain ¦
a light-sensitive diazonium salt, a light-sensitive quinone diazide com-pound, a light-sensitive azido compound or a light-sensitive photo-polymer composition. The solvent forming one part of the solution thus may be water or an organic solvent containing water, if required.
, The process will now be further described, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a schematic view of one embodiment of the process, Figure la is a schematic view of another embodiment, Figure 2 is a schematic view of still another embodiment of the proces s, and
-2-, '~ ' ' '' ' m4~slz Figure 3 is a schematic: enlarged view showinsl the lifting of the screen .
In the embodiment shown in Figure 1 a web-like carrier 2 for a copying layer is passed over a drum 1 turning in the direction indlcated by the arrow and is coated, in a manner not shown in detail, with a coating 6 composed of a solution 3 which contains the components of the light-sensitive layer to be applied. During this process and during the subsequent structuring of the coating 6, the carrier 2 of the copying layer lies on the drum 1. The structuring is effected by an endless web 7 composed of a fine-meshed net whlch is guided around the five rollers 4 and is pressed, on a portion of its path, into the coating 6 applied to the carrier 2 of the copying layer, the jacket of the drum 1 serving as an area of counter-pressure. The web-like net 7 turns in the same dire~
tlon as the web-like carrier 2 of the layer and at the same speed. After the web-like net 7 has been removed from the coating 6 by guiding it around one of the five rollers 4, the carrier web 2 provided with the structured coating 6' reaches a drying chamber 10 in which the coating is dried in known manner. After removal from the GOating 6, the fine-~meshed screen web 7 is passed through a cleaning bath 5 . Tn another ` 20 version of this embodiment shown in Figure la the fine-meshed screen 7 is laid on the carrier 2 of the copying layer and then the coating solution
In the embodiment shown in Figure 1 a web-like carrier 2 for a copying layer is passed over a drum 1 turning in the direction indlcated by the arrow and is coated, in a manner not shown in detail, with a coating 6 composed of a solution 3 which contains the components of the light-sensitive layer to be applied. During this process and during the subsequent structuring of the coating 6, the carrier 2 of the copying layer lies on the drum 1. The structuring is effected by an endless web 7 composed of a fine-meshed net whlch is guided around the five rollers 4 and is pressed, on a portion of its path, into the coating 6 applied to the carrier 2 of the copying layer, the jacket of the drum 1 serving as an area of counter-pressure. The web-like net 7 turns in the same dire~
tlon as the web-like carrier 2 of the layer and at the same speed. After the web-like net 7 has been removed from the coating 6 by guiding it around one of the five rollers 4, the carrier web 2 provided with the structured coating 6' reaches a drying chamber 10 in which the coating is dried in known manner. After removal from the GOating 6, the fine-~meshed screen web 7 is passed through a cleaning bath 5 . Tn another ` 20 version of this embodiment shown in Figure la the fine-meshed screen 7 is laid on the carrier 2 of the copying layer and then the coating solution
3 is applied to the carrier through the screen 7. Then, the screen 7 is removed .
In the embodiment shown in Figure 2 the coating 6 applied to a web-like carrier 2 for a copying layer is, after drying, subjected to the pressure of a fine-meshed web-like net 7 guided around the rollers 4 (in Figure 2, three rollers 4) in a manner similar to that shown in Fig-ure 1, while the carrier 2 for the copying layer lies on the drum 1.
~'.
10~51Z
Before being pressed onto the dr~ed coatirlg, the web-like net 7 is passed through a bath S. In this bath is a solvent In which the dried coating is soluble. In the bath 5 the net 7 takes up a quantlty of sol-vent sufficient for softening the dried coating 6.
As shown in an enlarged view in Figure 3, the process of the in-vention makes it possible to produce, in a relatively simple manner, printing plates having a structured light-sensitive copying layer. The fineness of the structuring easily can be adapted to individual require-ments simply by changing the fine-meshed screen used. In the process, 1~ the structured light-sensitive copying layer 6 assumes a shape 6' which corresponds approximately~to a positive image of the screen 7, i.e., the copying layer 6' is thicker in the areas 8 where the wires or flbers of the screen lay on the carrier of the copying layer than in the areas 9 where the holes 11 of the screen were. This has the advantage for the image reproduction that the entire surface, or essentially the entire sur-' face, of the carrier of the copying layer is covered by the light-sensitlve layer.
It will be obvious to those skilled in the art that many modifi-cations may be made w;thin the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.
' ,'' ... .
,.
'~''' ~' ,
In the embodiment shown in Figure 2 the coating 6 applied to a web-like carrier 2 for a copying layer is, after drying, subjected to the pressure of a fine-meshed web-like net 7 guided around the rollers 4 (in Figure 2, three rollers 4) in a manner similar to that shown in Fig-ure 1, while the carrier 2 for the copying layer lies on the drum 1.
~'.
10~51Z
Before being pressed onto the dr~ed coatirlg, the web-like net 7 is passed through a bath S. In this bath is a solvent In which the dried coating is soluble. In the bath 5 the net 7 takes up a quantlty of sol-vent sufficient for softening the dried coating 6.
As shown in an enlarged view in Figure 3, the process of the in-vention makes it possible to produce, in a relatively simple manner, printing plates having a structured light-sensitive copying layer. The fineness of the structuring easily can be adapted to individual require-ments simply by changing the fine-meshed screen used. In the process, 1~ the structured light-sensitive copying layer 6 assumes a shape 6' which corresponds approximately~to a positive image of the screen 7, i.e., the copying layer 6' is thicker in the areas 8 where the wires or flbers of the screen lay on the carrier of the copying layer than in the areas 9 where the holes 11 of the screen were. This has the advantage for the image reproduction that the entire surface, or essentially the entire sur-' face, of the carrier of the copying layer is covered by the light-sensitlve layer.
It will be obvious to those skilled in the art that many modifi-cations may be made w;thin the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.
' ,'' ... .
,.
'~''' ~' ,
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In the process for the production of a light-sensitive offset printing plate suitable for the reproduction of halftones in which a light-sensitive coating in a solvent is applied to an opaque carrier and dried, the improvement which comprises pressing a fine-meshed screen into the coating wet with solvent during the application of the coating to the opaque carrier, and then removing the screen.
2. A process according to claim 1 in which the screen is pressed into the coating and removed therefrom before the coating is dried.
3. A process according to claim 2 in which the screen is passed through a solvent for the coating material after the screen is removed from the coating whereby the screen is cleaned.
4. A process according to claim 1 in which the coating is dried and then wetted and softened by a solvent prior to pressing the screen into the coating.
5. A process according to claim 1 in which the coating is dried and is then wetted and softened by a solvent applied to the coating at the same time as the screen is pressed into the coating.
6. A process according to claim 5 in which the screen is passed through the solvent prior to pressing the screen into the coating whereby the screen applies the solvent.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19742439730 DE2439730C2 (en) | 1974-08-19 | 1974-08-19 | Method of making a photosensitive offset printing plate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1044512A true CA1044512A (en) | 1978-12-19 |
Family
ID=5923563
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA233,557A Expired CA1044512A (en) | 1974-08-19 | 1975-08-15 | Process for the production of a light-sensitive offset printing plate |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5814674B2 (en) |
| CA (1) | CA1044512A (en) |
| DE (1) | DE2439730C2 (en) |
| FR (1) | FR2282660A1 (en) |
| GB (1) | GB1514506A (en) |
| IT (1) | IT1041240B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57171591U (en) * | 1981-04-23 | 1982-10-28 | ||
| EP0109183A3 (en) * | 1982-10-14 | 1985-04-03 | Unilever Plc | Lithographic printing |
| JPS59181586U (en) * | 1983-05-20 | 1984-12-04 | 日本電池株式会社 | Leak-free lead acid battery |
| US4587199A (en) * | 1983-07-11 | 1986-05-06 | E. I. Du Pont De Nemours And Company | Controlled roughening of a photosensitive composition |
| DE3433247A1 (en) * | 1984-09-11 | 1986-03-20 | Hoechst Ag, 6230 Frankfurt | RADIATION-SENSITIVE RECORDING MATERIAL AND METHOD FOR THE PRODUCTION THEREOF |
| JPH0425295Y2 (en) * | 1985-05-13 | 1992-06-17 |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1813445C3 (en) * | 1968-12-09 | 1979-04-12 | Hoechst Ag, 6000 Frankfurt | Photosensitive copying material for the production of a collotype and process for the production of the collotype |
| US3891443A (en) * | 1973-02-01 | 1975-06-24 | Polychrome Corp | Mat finish photosensitive relief plates |
-
1974
- 1974-08-19 DE DE19742439730 patent/DE2439730C2/en not_active Expired
-
1975
- 1975-08-13 IT IT5094975A patent/IT1041240B/en active
- 1975-08-15 CA CA233,557A patent/CA1044512A/en not_active Expired
- 1975-08-15 GB GB3404175A patent/GB1514506A/en not_active Expired
- 1975-08-18 JP JP10005275A patent/JPS5814674B2/en not_active Expired
- 1975-08-18 FR FR7525487A patent/FR2282660A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE2439730A1 (en) | 1976-03-04 |
| DE2439730C2 (en) | 1983-09-15 |
| JPS5814674B2 (en) | 1983-03-22 |
| GB1514506A (en) | 1978-06-14 |
| FR2282660B3 (en) | 1978-04-07 |
| JPS5144004A (en) | 1976-04-15 |
| FR2282660A1 (en) | 1976-03-19 |
| IT1041240B (en) | 1980-01-10 |
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