Printing – Printing members – Plate mountings
Patent
1996-09-23
1998-02-10
Bennett, Christopher A.
Printing
Printing members
Plate mountings
1014011, B41F 2700
Patent
active
057157502
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a printing form attachment means for removably attaching a flexographic printing form by adhesion on a plate cylinder of a printing press, more particularly for removably attaching a printing form of photopolymeric material.
The known printing form attachment means of this type (EP 0 313 510) comprises a strip of double-sided adhesive tape, e.g. supplied from a roll, which is attached with one adherent side on the plate cylinder so that on the other adherent side one or more flexographic printing forms can be attached.
Flexographic printing forms consist of a photopolymeric layer attached to a support layer. Through a film, on which the desired images and/or text etc. have been recorded, the photopolymeric layer is exposed and then washed out, whereafter finally the resulting printing form is subjected to a subsequent treatment.
Reference is made to U.S. Pat. No. 3,210,187 which relates to photopolymeric elements such as printing plates with relief structures as well as processes for making the same.
In case of using the known printing form attachment means the problem arises that the support layer of the printing form adheres strongly to the adherent layer of the double-sided adhesive tape which serves as printing form attachment means, due to which removal of the printing form from the plate cylinder is troublesome and moreover a residual part of the adhesive layer often remains on the printing form. Consequently the printing form attachment means generally has to be replaced after having been used one or several times, whereas on the other hand the printing form has to be cleansed in order to remove the adhesive material. Because the cleansing operation of the printing form is intensive the printing form is commonly thrown away. Thus in case of a repeat order a new printing form has to be produced.
It is an object of this invention to provide a printing form attachment means of the type as mentioned in the preamble, which overcomes these disadvantages in a simple, but nevertheless effective way.
In accordance with the invention the printing form attachment means is characterized in that the printing form attachment means utilizes the adherent and sticky characteristics of a photopolymeric material in that it comprises a completely exposed photopolymeric printing form attachment layer for the removable adherent attachment of the printing form on the plate cylinder as well as a flexible support layer which supports the photopolymeric printing form attachment layer.
The invention relies on the recognition that in order to obtain a particularly effective printing form attachment means advantageously the adherent characteristics of a photopolymeric layer can be utilized. Experiments have shown that these adherent characteristics are maintained in case of intensive use during a period of at least 8 to 12 months. Moreover, on the one hand a good attachment of the printing form on the plate cylinder is realized, whereas on the other hand the printing form can relatively easily be removed from the adherent photopolymeric printing form attachment layer and no residual photopolymeric material remains on the printing form. This results in a long lifetime of the printing form attachment means applied to the plate cylinder, whereas on the other hand the printing form no longer needs to undergo a cleansing operation. Damaging of the printing form by the removal is excluded as well, so that the printing form is available several times for repeat orders without any problem.
Moreover, the printing form attachment means of the invention has the advantage that the photopolymeric layer is highly resistant to the solvents present in the used inks. A further important advantage is achieved in that the photopolymeric layer as compared with the adherent adhesive layers of the known double sided adhesive tape has a considerable thickness of 1-4 mm and a relatively low hardness and preferably is of at least 1.5 mm in thickness. In this way the photopolymeric layer of the printing form attachment means fo
REFERENCES:
patent: 3210187 (1965-10-01), Thommes
patent: 4871631 (1989-10-01), Pieper et al.
Bennett Christopher A.
Winkle Holding, B.V.
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