CA1329505C - Coating printing cylinders by applying a photocrosslinkable recording layer - Google Patents
Coating printing cylinders by applying a photocrosslinkable recording layerInfo
- Publication number
- CA1329505C CA1329505C CA000528651A CA528651A CA1329505C CA 1329505 C CA1329505 C CA 1329505C CA 000528651 A CA000528651 A CA 000528651A CA 528651 A CA528651 A CA 528651A CA 1329505 C CA1329505 C CA 1329505C
- Authority
- CA
- Canada
- Prior art keywords
- recording layer
- layer
- printing
- photocrosslinkable
- exposed
- 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 - Fee Related
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
- G03F7/20—Exposure; Apparatus therefor
- G03F7/24—Curved surfaces
-
- 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
- G03F5/00—Screening processes; Screens therefor
- G03F5/20—Screening processes; Screens therefor using screens for gravure printing
-
- 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
- G03F7/16—Coating processes; Apparatus therefor
- G03F7/18—Coating curved surfaces
-
- 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
- G03F7/20—Exposure; Apparatus therefor
- G03F7/2022—Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure
Landscapes
- 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)
- Peptides Or Proteins (AREA)
- Pens And Brushes (AREA)
- Medicines Containing Antibodies Or Antigens For Use As Internal Diagnostic Agents (AREA)
- Materials For Photolithography (AREA)
- Paper (AREA)
- Heat Sensitive Colour Forming Recording (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
Printing cylinders are coated by a process in which preprepared, solid, photocrosslinkable recording layers are mounted the said recording layers being pre-exposed beforehand from the back through a halftone transparency in such a way that the layers are still thermoplastically deformable and are preferably still weldable. Printing cylinders coated in this manner can be further processed to give continuous or seamless coated pringing cylinders and printing forms for rotary printing, which permit satisfactory printing of low tonal values.
Printing cylinders are coated by a process in which preprepared, solid, photocrosslinkable recording layers are mounted the said recording layers being pre-exposed beforehand from the back through a halftone transparency in such a way that the layers are still thermoplastically deformable and are preferably still weldable. Printing cylinders coated in this manner can be further processed to give continuous or seamless coated pringing cylinders and printing forms for rotary printing, which permit satisfactory printing of low tonal values.
Description
~ 32~
- 1 - O.Z. 0050/38244 Coating printing cylinders by applying a photocrosslink-able recording layer The present invention relates to a process for coating printing cylinders or sleeves by applying a pre-prepared, solid photocrosslinkable recording layer, whichhas been preexposed from the back, with simultaneous or subsequent exposure to heat and/or application of pressure, and printing forms which have been produced in this man-ner and are suitable for rotary printing.
Processes for coating and in particular continuous coating of uncoated or precoated printing cylinders or sleeves having a photocrosslinkable recording layer by mounting a preprepared solid recarding layer onto the said printing cylinders or sleeves in order to produce print-ing forms for rotary printing are known per se. Regard-ing the prior art, reference may be made, for example, to EP-A 40 893, 43 6Z3, 111 371, DE-B 27 22 896 and ~E-A
28 42 440, 28 44 4Z6, 29 11 908 and 31 25 564. It is also known that photocrosslinkable recording layers can be mounted onto the cylinders or sleeves and the abutting edges of the unexposed applied reco~ding layers can be welded under the action heat without a seam and/or the re-sulting surfaces of the layer can be shaped or calendered.
The disadvantage of the known procedures is that the con-vent;onal preexposure of the photosensitive recordinglayer through the back, as described in, for example, US-A
3 210 187, 3 259 499 or 34 0& 191~ is not possible.
In the case of negative working material, the conventional uniform preexposure through the back is known to lead to photocrosslinking of the lower region of the recording layer before i~agewise -~a;~n exposure from ~he front produces imagewise crosslinking in the exposed parts of the uncrosslinked residual layer, the said cross-linking resulting in the relief structure intended for printing, after development, for example washing out of the unexposed parts of the imagewise exposed residual layer.
~32~
- 1 - O.Z. 0050/38244 Coating printing cylinders by applying a photocrosslink-able recording layer The present invention relates to a process for coating printing cylinders or sleeves by applying a pre-prepared, solid photocrosslinkable recording layer, whichhas been preexposed from the back, with simultaneous or subsequent exposure to heat and/or application of pressure, and printing forms which have been produced in this man-ner and are suitable for rotary printing.
Processes for coating and in particular continuous coating of uncoated or precoated printing cylinders or sleeves having a photocrosslinkable recording layer by mounting a preprepared solid recarding layer onto the said printing cylinders or sleeves in order to produce print-ing forms for rotary printing are known per se. Regard-ing the prior art, reference may be made, for example, to EP-A 40 893, 43 6Z3, 111 371, DE-B 27 22 896 and ~E-A
28 42 440, 28 44 4Z6, 29 11 908 and 31 25 564. It is also known that photocrosslinkable recording layers can be mounted onto the cylinders or sleeves and the abutting edges of the unexposed applied reco~ding layers can be welded under the action heat without a seam and/or the re-sulting surfaces of the layer can be shaped or calendered.
The disadvantage of the known procedures is that the con-vent;onal preexposure of the photosensitive recordinglayer through the back, as described in, for example, US-A
3 210 187, 3 259 499 or 34 0& 191~ is not possible.
In the case of negative working material, the conventional uniform preexposure through the back is known to lead to photocrosslinking of the lower region of the recording layer before i~agewise -~a;~n exposure from ~he front produces imagewise crosslinking in the exposed parts of the uncrosslinked residual layer, the said cross-linking resulting in the relief structure intended for printing, after development, for example washing out of the unexposed parts of the imagewise exposed residual layer.
~32~
- 2 - o.Z. 0050/3824L
9ecause, inter alia, the remaining uncrosslinked record-ing layer is fairly thin but sufficient for the relief structure, preexposure from the back makes it possible significantLy to reduce the time required for image~ise main exposure and to achieve good anchoring of even fine relief elements of the developed print relief, coupled with satisfactory shadow well depths of the relief struc-ture. }f no preexposure from the back is carried out, longer times have to be emoloyed for the main ;ma~e-wise exposure in order to achieve adequate anchoring offine relief elements, which readily leads to closing of the shadow well depth in the case of fine negative image elements. However, if photocrosslinkable recording layers to be mounted on a printing cylinder are preexposed uni-formly from the back before being applied, difficultiesare encountered. At the abutting edges of the recording layer preexposed uniformly from the back, the layer material can no longer be satisfactorily welded, as is advantageous for the production of continuous print;ng cylinders, since, as is known, it is possible satisfac-torily to weld only an uncrosslinked polymer layer and not an exposed, crosslinked polymer layer. Furthermore, a crosslinked polymer layer in contact with the printing cylinder or sleeve exhibits substantially poorer adhesion.
Because pree~posure from the back is impossible in the case of printing cylinders prov;ded with a recording layer or in the case of the recording layer prior to mounting on the cylinder, it is generally impossible to achieve the same lo~ tonal values during printing with the printing forrns on the printing cylinders as with corresponding flat photocrosslinkable printing plates which permit pre-exposure from the back.
We have found that these disadvantages can be overcome if the photosensitive recording layers mounted on the printing cylinders or sleeves have been preexposed from the back through a screen, so that, in the rear or lower level of the layer, only discrete volurne elernents 132~5~5 - 3 - O.Z. 0050/38Z44 or portions have been photocrosslinked or photopolymerized by the pre-exposure and uncrosslinked or photopolymeriz-able layer material is still present in bet~een in the rear level of the layer, this layer material making it possible for the layer to be shaped by a thermoplastic method, in particular to be adequately welded, in spite of the incorporated crosslinked regions.
The present invention therefore relates to a proc-ess for coating printing cylinders or sleeves by mounting a preprepared, solid, photocrosslinkable recording layer, which, in order to reduce the time required for main imagewise e~posure and to improve anchoring of the relief of the mounted recording layer, has been pre-exposed beforehand from the back, ie. through that side of the layer which faces the printing cylinder or sleeve, on the uncoated or precoated pr;nting or sleeve, with simultan-eous or subsequent e~posure to heat and/or application of pressure, wherein the photocrosslinkable recording layer mounted has been pre-exposed beforehand from the back through a pattern-bearin9 transparency, in particllar a screen, so ~hat the layer can still be shaped by a thermo-plastic method, in particular can still be weldecl.
The present invention furthermore relates to coated printing cylinders produced in this manner and printing forns which are produced $rom the said cylinders by imagewise exposure followed by clevelopment and which are particularly useful for rotary printing.
The process according to the invention is part-icularly suitable for the production of continuously coated printing cylinders since it permits welding of the abutting edges of the mounted photocrosslinkabLe recording layers as well as shaping of the said layers by a thermoplastic method or calendering of their surfaces.
The photopolymer printin~ forms prepared from the products in a conventional manner can be used in rotarr printing to produce high quality prints having low tonal values too, in long print runs. Moreover, in spite of 1329~
, - 4 - O.Z. 0050/38244 the pre-exposure from the back, the novel products permit good adhesion of the printing plates, in particùlar of flexographic printing plates, to the cylinder surface, ;n particular to metallic cylinder surfaces too, ~hich is evident from the following. If exposure from the back is carried out, for example, using a point light source and a screen of 10% tonal value, a sort of nail board is produced in the ther~oplastically deformable layer, at ~he level of the layer which has been exposed in this manner. At the 1û exposed points (nails) crosslinked in ~his manner, the adhesion is poor, while the unexposed and uncrosslinked points inbetween exhib;t good or very good aclhesion of the layer. Thus, the layer as a whole adheres firmly to the printing cylinder or sleeve after mounting and exposure to heat and/or application of pressure, and provides good anchoring of the layer even on roughened cylinder surfaces.
Preprepared solid photocrosslinkable layers which are suitable for use in the novel process are 3ll layers of materials which, prior to exposure and pre-exposure, can be shaped by a thermoplastic method and can be bonded to one another under the controlled action of heat and/or pressure, without their crosslinkability being adversely effected by irradiation. These include, in particular, the solid, polymeric, photosensitive layers which soften on heating and flow or stick under pressure, as are known per se for the production of printing forms and relief forms. Particular examples here are the positive working or negative working, photosensitive, PhotoPolymerizable layers. Suitable photopolymerizable layers contain in generaL one or more polymeric binders, eg. soluble nylons, partially hydrolyzed polyvinyl acetates, modified poly-vinyl alcohols, polyurethanes, dienepolymers, eg. block copolymers of styrene, butadiene and/or isoPrene or but-adiene/acryloni~rile copolymers, one or more low nolecularweight, ethylenically unsaturated, photopolymerizable compounds, for example the known (meth)acrylate-containing ~32~
- S - O.Z. 0~50/38244 or (meth)acrylamido-containing monomers, one or more photopolymeri~ation initiators, eg. benzoin ether, benzil monoketals or acylphosphine oxides, and convention-al additives and/or assistants, for example ther~al poly-S merization inhibitors, dyes, pigments, f;llers, plasti-cizers, lev@lling agents, sensitometric regulators, etc.
The photosensitive photopolymerizable layers, thus have been disclosed and described for the production of flexo-graphic printing forms or gravure printing forms (cf. for 10 example D~-A Z2 15 090, DE-A-Z9 02 412~ EP-9-27 612, DE-A-20 61 287, EP-A-70 510 and EP-A-70 511), are particularly suitable for th~ novel process. The thickness of the photosensitive layers to be used is not critical in the process according to the invention and, as stated, can be 15 varied within wide limits. The layer is usually from about 500 ~m to about 7 mm thick.
Photocrosslinkable recording layers without a base are preferably mounted, the said layers having been cut to size beforehand to fit the particular cylinder 20 circumference; cut edges which are even and clean are advantageous. In some cases, the photocrosslinkab~e recording layers may also contain a woven or nonwoven, preferably transparent insert as reinforcement in the lower part of the layer, which is not required for sub-25 sequent formation of the relief structure by imagewiseexposure followed by development.
Particularly suitable printing cylinders or sleeves are cyl;nders, cylindrical sleeves or conical sleeves, such as those which are known to be used for coating in 3û order to produce cylindrical printing plates and Print-ing forms for rotary printing. They are advantageously roughened and may also be coated. The surface of the printing cylinders or sleeves consist, in particular, of metal, plastic or rubber, on which, for example, adhesion-3S promoting layers may be applied.
The recording layer can be mounted on the uncoatedor coated printing cylinders or sleeves in a conventional ~329~
- 6 - O.Z. 0050/38244 manner with simultaneous o~ subsequent application of a vacuum between the cylinder and the recording layer or of a plastic fil0 or shrink film which covers them. In this respect, reference may be made to the prior art cited S above. This also applies to the production of continuously coated printing cylinders without surface deformation, and of printing forms which permit seamless rotary printing.
A shape-imparting after treatment of the mounted record-ing layers serves primarily to produce a continuous, uniform, seamless photocrosslinkable recording layer.
~t compensates any small fluctuations in layer thickness and produces an exact cylindrical periphery. It is also possible for the surface to be calendered in a conven-tional manner.
The particular characteristic feature of the novel process is that the recording layers mounted on the printing cylinders or sleeves are photocrosslinkable recording layers of the stated type which, before being mounted are pre exposed through a pattern-bearing transparency from the bac~ ie. from that side which subsequently faces the printing cylinder base.
As stated above, uniform pre-exposure of printing plates from the back is known and is familiar to the skilled worker and achieves the positive effects stated above, in particular a significant reduction in the time required for the principle imagewise exposure from the other side of the layer. On the other hand, the record-ing layers used for the novel process are not pre-exposed uniformly from the back but are pre-exposed through a 3~ pattern-bearing~egative from the back in such a way that the resulting ~ecording layer can still be deformed by a thermoplastic 0ethod and preferably possesses sufficient weldability in the lower levels of the layer too, but also permits a noticeable reduction in the time required for the principle image~ise exposure. The discrete pre-exposure or pre-exposure through a pattern-bearing transparency from the back has the function of fixing certain discrete 132~
- 7 - O.Z. 0050/38Z44 regions of molecules so that the parts of the layer behave as though they were crosslinked and the uncrosslinked and mobile molecules surrounding the crosslinked parts in the layer act as lubricants but just permit sufficient thermo-S plastic deformation, in ~articular welding of the layeror parts of the layer (ballbearing effect).
This can be achieved, in particular, by pre-expos-ure from the back through films having coarse screens of from 5 to Z5, preferably 5 to 15, lines/cm. A tonal value of from 5 to 30~, in particular from 5 to 15~, is very suitable. Particularly advantageous results, ie.
a pronounced pre-exposure effect with the layer still being weldable, were obtained by dot-like pre-exposure through the transparency, but the shape of the dot may also be varied, for example converted to a diamond shape, a small square or rectangle, etc.
The time of the pre-exposure to actinic light from the back determines not only the particular extent of the exposed crosslinked parts of the layer but especi-ally the thickness or depth of crosslinking in the pre-exposed regions of the layer. The depth of crosslinking resul~ing from pre-exposure through the back is only a fraction of the total thickness of the recording layer and must not penetrate into the upper levels of the layer which are required to form an adequate relief structure by principle imagewise exposure from the other side of the layer. On the other hand, the adequate crosslinking depth obtained by pre-exposure from the back should per-mit a substantial reduction in the required main imagewise exposure time and provide satisfactory anchoring of even fine relief elements of the deve~oped printing form. However, since this objective is familiar to the skilled worker and is determined not only by the desired depth of the printing relief but to a great extent by the chemical composition of the photocrosslinkable rec-ording layer, the pre-exposure ti~e required to achieve an optimum pre-exposure effect while retaining thermo-1 3 2 Yl ~ 0 5 - 8 - O.Z. 0050/38244 plastic deformability, in particular weldability of the layer, can readily be determined by a few preliminary experiments. It is in general shorter than the main exposure time required.
S The Example which follows illustrates the invention.
EXAMPLE
A photocrosslinkable elastameric printing plate which contained an A-9-C block copolymer with a polystyrene~
a polyisoprene and a styrene/isoprene copoly0er block as the binder, di(meth)acrylates as monomers, benzyl dimethyl ketal as the photoinitiator, a black dye and a commercia~
methylstyrene/vinyltoluene copolymer, had no base and had been cut exactly to correspond to the size of the cylinder was mounted in a conventional manner on a thin-walled printing cylinder which had a nickel surface, a length of about 110 cm and a diameter of about 120 mm. ~efore being mounted, the 3 mm thick elastomeric printing plate was pre-exposed from the back through a pattern-bearing transparency having a screen of 5 lines/cm and 10~ tonal value in a tube exposure unit. The edges of the mounted flexographic recording layer were welded satisfactorily at about 130C, and the surface of the layer was calendered. The adhesion of the mounted recording layer to the nickel printing cylinder was very good.
The printing cylinder with the mounted elastomeric printing plate which had been pre-exposed from the back was then exposed i0agewise from the front in a rotary, cylinderical unit, and the unexposed parts of the layer were washed out. The resulting printing relief ~as about 1 mm deep and made it Possible to print satisfactory tonal values of from 1 to 2~, as is achievable ~ith the same, flat flexographic printing Plates after uniform exposure from the back.
9ecause, inter alia, the remaining uncrosslinked record-ing layer is fairly thin but sufficient for the relief structure, preexposure from the back makes it possible significantLy to reduce the time required for image~ise main exposure and to achieve good anchoring of even fine relief elements of the developed print relief, coupled with satisfactory shadow well depths of the relief struc-ture. }f no preexposure from the back is carried out, longer times have to be emoloyed for the main ;ma~e-wise exposure in order to achieve adequate anchoring offine relief elements, which readily leads to closing of the shadow well depth in the case of fine negative image elements. However, if photocrosslinkable recording layers to be mounted on a printing cylinder are preexposed uni-formly from the back before being applied, difficultiesare encountered. At the abutting edges of the recording layer preexposed uniformly from the back, the layer material can no longer be satisfactorily welded, as is advantageous for the production of continuous print;ng cylinders, since, as is known, it is possible satisfac-torily to weld only an uncrosslinked polymer layer and not an exposed, crosslinked polymer layer. Furthermore, a crosslinked polymer layer in contact with the printing cylinder or sleeve exhibits substantially poorer adhesion.
Because pree~posure from the back is impossible in the case of printing cylinders prov;ded with a recording layer or in the case of the recording layer prior to mounting on the cylinder, it is generally impossible to achieve the same lo~ tonal values during printing with the printing forrns on the printing cylinders as with corresponding flat photocrosslinkable printing plates which permit pre-exposure from the back.
We have found that these disadvantages can be overcome if the photosensitive recording layers mounted on the printing cylinders or sleeves have been preexposed from the back through a screen, so that, in the rear or lower level of the layer, only discrete volurne elernents 132~5~5 - 3 - O.Z. 0050/38Z44 or portions have been photocrosslinked or photopolymerized by the pre-exposure and uncrosslinked or photopolymeriz-able layer material is still present in bet~een in the rear level of the layer, this layer material making it possible for the layer to be shaped by a thermoplastic method, in particular to be adequately welded, in spite of the incorporated crosslinked regions.
The present invention therefore relates to a proc-ess for coating printing cylinders or sleeves by mounting a preprepared, solid, photocrosslinkable recording layer, which, in order to reduce the time required for main imagewise e~posure and to improve anchoring of the relief of the mounted recording layer, has been pre-exposed beforehand from the back, ie. through that side of the layer which faces the printing cylinder or sleeve, on the uncoated or precoated pr;nting or sleeve, with simultan-eous or subsequent e~posure to heat and/or application of pressure, wherein the photocrosslinkable recording layer mounted has been pre-exposed beforehand from the back through a pattern-bearin9 transparency, in particllar a screen, so ~hat the layer can still be shaped by a thermo-plastic method, in particular can still be weldecl.
The present invention furthermore relates to coated printing cylinders produced in this manner and printing forns which are produced $rom the said cylinders by imagewise exposure followed by clevelopment and which are particularly useful for rotary printing.
The process according to the invention is part-icularly suitable for the production of continuously coated printing cylinders since it permits welding of the abutting edges of the mounted photocrosslinkabLe recording layers as well as shaping of the said layers by a thermoplastic method or calendering of their surfaces.
The photopolymer printin~ forms prepared from the products in a conventional manner can be used in rotarr printing to produce high quality prints having low tonal values too, in long print runs. Moreover, in spite of 1329~
, - 4 - O.Z. 0050/38244 the pre-exposure from the back, the novel products permit good adhesion of the printing plates, in particùlar of flexographic printing plates, to the cylinder surface, ;n particular to metallic cylinder surfaces too, ~hich is evident from the following. If exposure from the back is carried out, for example, using a point light source and a screen of 10% tonal value, a sort of nail board is produced in the ther~oplastically deformable layer, at ~he level of the layer which has been exposed in this manner. At the 1û exposed points (nails) crosslinked in ~his manner, the adhesion is poor, while the unexposed and uncrosslinked points inbetween exhib;t good or very good aclhesion of the layer. Thus, the layer as a whole adheres firmly to the printing cylinder or sleeve after mounting and exposure to heat and/or application of pressure, and provides good anchoring of the layer even on roughened cylinder surfaces.
Preprepared solid photocrosslinkable layers which are suitable for use in the novel process are 3ll layers of materials which, prior to exposure and pre-exposure, can be shaped by a thermoplastic method and can be bonded to one another under the controlled action of heat and/or pressure, without their crosslinkability being adversely effected by irradiation. These include, in particular, the solid, polymeric, photosensitive layers which soften on heating and flow or stick under pressure, as are known per se for the production of printing forms and relief forms. Particular examples here are the positive working or negative working, photosensitive, PhotoPolymerizable layers. Suitable photopolymerizable layers contain in generaL one or more polymeric binders, eg. soluble nylons, partially hydrolyzed polyvinyl acetates, modified poly-vinyl alcohols, polyurethanes, dienepolymers, eg. block copolymers of styrene, butadiene and/or isoPrene or but-adiene/acryloni~rile copolymers, one or more low nolecularweight, ethylenically unsaturated, photopolymerizable compounds, for example the known (meth)acrylate-containing ~32~
- S - O.Z. 0~50/38244 or (meth)acrylamido-containing monomers, one or more photopolymeri~ation initiators, eg. benzoin ether, benzil monoketals or acylphosphine oxides, and convention-al additives and/or assistants, for example ther~al poly-S merization inhibitors, dyes, pigments, f;llers, plasti-cizers, lev@lling agents, sensitometric regulators, etc.
The photosensitive photopolymerizable layers, thus have been disclosed and described for the production of flexo-graphic printing forms or gravure printing forms (cf. for 10 example D~-A Z2 15 090, DE-A-Z9 02 412~ EP-9-27 612, DE-A-20 61 287, EP-A-70 510 and EP-A-70 511), are particularly suitable for th~ novel process. The thickness of the photosensitive layers to be used is not critical in the process according to the invention and, as stated, can be 15 varied within wide limits. The layer is usually from about 500 ~m to about 7 mm thick.
Photocrosslinkable recording layers without a base are preferably mounted, the said layers having been cut to size beforehand to fit the particular cylinder 20 circumference; cut edges which are even and clean are advantageous. In some cases, the photocrosslinkab~e recording layers may also contain a woven or nonwoven, preferably transparent insert as reinforcement in the lower part of the layer, which is not required for sub-25 sequent formation of the relief structure by imagewiseexposure followed by development.
Particularly suitable printing cylinders or sleeves are cyl;nders, cylindrical sleeves or conical sleeves, such as those which are known to be used for coating in 3û order to produce cylindrical printing plates and Print-ing forms for rotary printing. They are advantageously roughened and may also be coated. The surface of the printing cylinders or sleeves consist, in particular, of metal, plastic or rubber, on which, for example, adhesion-3S promoting layers may be applied.
The recording layer can be mounted on the uncoatedor coated printing cylinders or sleeves in a conventional ~329~
- 6 - O.Z. 0050/38244 manner with simultaneous o~ subsequent application of a vacuum between the cylinder and the recording layer or of a plastic fil0 or shrink film which covers them. In this respect, reference may be made to the prior art cited S above. This also applies to the production of continuously coated printing cylinders without surface deformation, and of printing forms which permit seamless rotary printing.
A shape-imparting after treatment of the mounted record-ing layers serves primarily to produce a continuous, uniform, seamless photocrosslinkable recording layer.
~t compensates any small fluctuations in layer thickness and produces an exact cylindrical periphery. It is also possible for the surface to be calendered in a conven-tional manner.
The particular characteristic feature of the novel process is that the recording layers mounted on the printing cylinders or sleeves are photocrosslinkable recording layers of the stated type which, before being mounted are pre exposed through a pattern-bearing transparency from the bac~ ie. from that side which subsequently faces the printing cylinder base.
As stated above, uniform pre-exposure of printing plates from the back is known and is familiar to the skilled worker and achieves the positive effects stated above, in particular a significant reduction in the time required for the principle imagewise exposure from the other side of the layer. On the other hand, the record-ing layers used for the novel process are not pre-exposed uniformly from the back but are pre-exposed through a 3~ pattern-bearing~egative from the back in such a way that the resulting ~ecording layer can still be deformed by a thermoplastic 0ethod and preferably possesses sufficient weldability in the lower levels of the layer too, but also permits a noticeable reduction in the time required for the principle image~ise exposure. The discrete pre-exposure or pre-exposure through a pattern-bearing transparency from the back has the function of fixing certain discrete 132~
- 7 - O.Z. 0050/38Z44 regions of molecules so that the parts of the layer behave as though they were crosslinked and the uncrosslinked and mobile molecules surrounding the crosslinked parts in the layer act as lubricants but just permit sufficient thermo-S plastic deformation, in ~articular welding of the layeror parts of the layer (ballbearing effect).
This can be achieved, in particular, by pre-expos-ure from the back through films having coarse screens of from 5 to Z5, preferably 5 to 15, lines/cm. A tonal value of from 5 to 30~, in particular from 5 to 15~, is very suitable. Particularly advantageous results, ie.
a pronounced pre-exposure effect with the layer still being weldable, were obtained by dot-like pre-exposure through the transparency, but the shape of the dot may also be varied, for example converted to a diamond shape, a small square or rectangle, etc.
The time of the pre-exposure to actinic light from the back determines not only the particular extent of the exposed crosslinked parts of the layer but especi-ally the thickness or depth of crosslinking in the pre-exposed regions of the layer. The depth of crosslinking resul~ing from pre-exposure through the back is only a fraction of the total thickness of the recording layer and must not penetrate into the upper levels of the layer which are required to form an adequate relief structure by principle imagewise exposure from the other side of the layer. On the other hand, the adequate crosslinking depth obtained by pre-exposure from the back should per-mit a substantial reduction in the required main imagewise exposure time and provide satisfactory anchoring of even fine relief elements of the deve~oped printing form. However, since this objective is familiar to the skilled worker and is determined not only by the desired depth of the printing relief but to a great extent by the chemical composition of the photocrosslinkable rec-ording layer, the pre-exposure ti~e required to achieve an optimum pre-exposure effect while retaining thermo-1 3 2 Yl ~ 0 5 - 8 - O.Z. 0050/38244 plastic deformability, in particular weldability of the layer, can readily be determined by a few preliminary experiments. It is in general shorter than the main exposure time required.
S The Example which follows illustrates the invention.
EXAMPLE
A photocrosslinkable elastameric printing plate which contained an A-9-C block copolymer with a polystyrene~
a polyisoprene and a styrene/isoprene copoly0er block as the binder, di(meth)acrylates as monomers, benzyl dimethyl ketal as the photoinitiator, a black dye and a commercia~
methylstyrene/vinyltoluene copolymer, had no base and had been cut exactly to correspond to the size of the cylinder was mounted in a conventional manner on a thin-walled printing cylinder which had a nickel surface, a length of about 110 cm and a diameter of about 120 mm. ~efore being mounted, the 3 mm thick elastomeric printing plate was pre-exposed from the back through a pattern-bearing transparency having a screen of 5 lines/cm and 10~ tonal value in a tube exposure unit. The edges of the mounted flexographic recording layer were welded satisfactorily at about 130C, and the surface of the layer was calendered. The adhesion of the mounted recording layer to the nickel printing cylinder was very good.
The printing cylinder with the mounted elastomeric printing plate which had been pre-exposed from the back was then exposed i0agewise from the front in a rotary, cylinderical unit, and the unexposed parts of the layer were washed out. The resulting printing relief ~as about 1 mm deep and made it Possible to print satisfactory tonal values of from 1 to 2~, as is achievable ~ith the same, flat flexographic printing Plates after uniform exposure from the back.
Claims (8)
1. A process for coating printing cylinders or sleeves by mounting a prepared, solid, photocrosslinkable recording layer, which, in order to reduce the time required for main imagewise exposure and to improve anchoring of the relief of the mounted recording layer, has been pre-exposed beforehand from the back, through that side of the layer which faces the printing cylinder or sleeve, on the uncoated or precoated printing or sleeve, with simultaneous or subsequent exposure to heat and/or application of pressure, wherein the photocrosslinkable recording layer is pre-exposed from the back before mounting through a pattern-bearing transparency so that the layer is still thermoplastic on mounting.
2. A process as claimed in claim 1, wherein the recording layer which as been pre-exposed from the back is still weldable.
3. A process as claimed in claim 1, wherein the recording layer which as been pre-exposed from the back possesses, in the rear of the layer, discrete photocrosslinked parts of the layer which are bordered by photocrosslinkable material of the recording layer.
4. A process as claimed in claim 1, wherein the recording layer has been pre-exposed from the back through a pattern-bearing transparency having from 5 to 25 lines/cm.
5. A process as claimed in claim 1, wherein the recording layer has been pre-exposed from the back through a pattern-bearing transparency having a tonal value of from 5 to 30%.
6. A process as claimed in claim 1, wherein the photocrosslinkable recording layer is a flexographic printing plate.
7. A process as claimed in claim 1, wherein a continuously coated printing cylinder is produced by welding the abutting edges of the mounted recording layer and, if necessary, subjecting the recording layer to an after treatment to impart shape.
8. A process according to anyone of claim 1 to 7, wherein said printing cylinder or sleeve is flexographic and said recording layer mounted thereon has a thickness of about 500 µm to about 7 mm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3603087.2 | 1986-02-01 | ||
| DE19863603087 DE3603087A1 (en) | 1986-02-01 | 1986-02-01 | METHOD FOR COATING PRINT CYLINDERS BY APPLYING A PHOTO-NETWORKABLE RECORD LAYER |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1329505C true CA1329505C (en) | 1994-05-17 |
Family
ID=6293145
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000528651A Expired - Fee Related CA1329505C (en) | 1986-02-01 | 1987-01-30 | Coating printing cylinders by applying a photocrosslinkable recording layer |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0231902B1 (en) |
| JP (1) | JPS62186267A (en) |
| AT (1) | ATE59908T1 (en) |
| CA (1) | CA1329505C (en) |
| DE (2) | DE3603087A1 (en) |
| DK (1) | DK168717B1 (en) |
| ES (1) | ES2019303B3 (en) |
| FI (1) | FI88216C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8066837B2 (en) | 2004-10-14 | 2011-11-29 | Flint Group Germany Gmbh | Processes and apparatus for producing photopolymerizable, cylindrical, continuous, seamless flexographic printing elements |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0487260A1 (en) * | 1990-11-19 | 1992-05-27 | Canon Kabushiki Kaisha | Printing method |
| FR2735717B1 (en) * | 1995-06-22 | 1997-08-08 | Photomeca Egg | METHOD FOR MANUFACTURING PHOTOPOLYMER PLATES BY DOUBLE IRRADIATION FROM BELOW |
| JP2001188354A (en) * | 1999-12-28 | 2001-07-10 | Asahi Kasei Corp | Method for manufacturing photosensitive resin letterpress and apparatus for manufacturing the same |
| DE10112761A1 (en) | 2000-04-13 | 2001-10-18 | Heidelberger Druckmasch Ag | Method for using a printing plate for illustrating and flexographic printing involves securing printing plate by magnetic cylinder in illustrating machine and then undertaking printing using illustrated plate |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE408744A (en) * | 1935-04-01 | |||
| US3663222A (en) * | 1968-06-06 | 1972-05-16 | Asahi Chemical Ind | Process for preparing steric block with liquid photopolymerizable composition |
| DE1772662B1 (en) * | 1968-06-15 | 1971-10-14 | Asahi Chemical Ind | Process for the photographic production of a relief plate bearing a photopolymerizate three-dimensional image |
| DE2542815C2 (en) * | 1974-09-26 | 1983-07-14 | Asahi Kasei Kogyo K.K., Osaka | Process for the production of printing forms by photomechanical means |
| DE2722896C3 (en) * | 1977-05-20 | 1986-01-02 | Du Pont de Nemours (Deutschland) GmbH, 4000 Düsseldorf | Process for the edge joining of light-curable thermoplastic elastomer printing plates |
| DE2964409D1 (en) * | 1978-07-10 | 1983-02-03 | Akzo Nv | Process and apparatus for the manufacture of a relief printing form |
-
1986
- 1986-02-01 DE DE19863603087 patent/DE3603087A1/en not_active Withdrawn
-
1987
- 1987-01-30 FI FI870422A patent/FI88216C/en not_active IP Right Cessation
- 1987-01-30 EP EP87101295A patent/EP0231902B1/en not_active Expired - Lifetime
- 1987-01-30 DE DE8787101295T patent/DE3767172D1/en not_active Expired - Lifetime
- 1987-01-30 CA CA000528651A patent/CA1329505C/en not_active Expired - Fee Related
- 1987-01-30 JP JP62018796A patent/JPS62186267A/en active Pending
- 1987-01-30 DK DK049787A patent/DK168717B1/en not_active IP Right Cessation
- 1987-01-30 ES ES87101295T patent/ES2019303B3/en not_active Expired - Lifetime
- 1987-01-30 AT AT87101295T patent/ATE59908T1/en not_active IP Right Cessation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8066837B2 (en) | 2004-10-14 | 2011-11-29 | Flint Group Germany Gmbh | Processes and apparatus for producing photopolymerizable, cylindrical, continuous, seamless flexographic printing elements |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0231902B1 (en) | 1991-01-09 |
| DK49787D0 (en) | 1987-01-30 |
| JPS62186267A (en) | 1987-08-14 |
| FI88216C (en) | 1993-04-13 |
| ES2019303B3 (en) | 1991-06-16 |
| FI870422A (en) | 1987-08-02 |
| FI870422A0 (en) | 1987-01-30 |
| DK168717B1 (en) | 1994-05-24 |
| ATE59908T1 (en) | 1991-01-15 |
| EP0231902A3 (en) | 1988-08-31 |
| EP0231902A2 (en) | 1987-08-12 |
| DE3767172D1 (en) | 1991-02-14 |
| DK49787A (en) | 1987-08-02 |
| DE3603087A1 (en) | 1987-08-06 |
| FI88216B (en) | 1992-12-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |