EP1240021B1 - Sleeve comprising means for fixing printing plates and method for making same - Google Patents

Abstract

The invention concerns an endless sleeve comprising at least a substantially cylindrical support and whereof the outer surface is coated with at least a layer of bonding and permanently adhesive material. Said sleeve is designed to be mounted on a support cylinder, while its outer surface enables printing plates to be removably fixed by adhesion. The invention is applicable for flexographic printing.

Description

The invention relates to the field of printing and more particularly the fixing of printing plates or pictures on machine support cylinders printing or on sleeves provided on these cylinders.

We know that such printing plates are especially used for flexographic printing.

These printing plates conventionally include a layer of photopolymer, placed on a support. Before that the printing plate is not used, the layer of photopolymer is developed to obtain a layer with reliefs which will allow the image to be reproduced to print.

The printing plates are generally reused several times. It is therefore desirable to have fastening means now efficiently the plates during printing, while allowing their removing the plate cylinder or attached sleeve on the cylinder for later reuse.

Known means for fixing the plates printing consist of double-sided adhesive strips.

Each strip of adhesive is fixed by one side adhesive, directly on the plate cylinder or on a sleeve fixed on the cylinder, while one or multiple printing plates are attached to each other side of the band.

These double-sided adhesives have many disadvantages.

First, it happens that part of the adhesive stays attached to the printing plate after it has been removed from the cylinder or sleeve attached to the cylinder. It is then necessary to clean the plate to remove residual adhesive, before any new use of the plate.

In addition, the use of double-sided adhesive turns out to be expensive, considering the price of the adhesive itself and the operations it requires.

The object of the invention is to overcome these disadvantages by proposing a sleeve, intended to be fixed on a cylinder and comprising fixing means printing plates which are simple to manufacture and a low cost price.

The invention thus relates to an endless sleeve, comprising at least one substantially shaped support cylindrical and the outer surface of which is covered at least one layer of a sticky and adherent material permanently, said sleeve being intended to be mounted on a support cylinder, while its surface exterior allows removable fixing by adhesion of printing plates.

Throughout the description, we understand by sticky and permanently adherent material, a material with bonding and adhesion properties last over time, typically for a period of at least minus 8 to 12 months.

Thus, the sleeve according to the invention, after its mounting on a support cylinder or plate holder, allows avoid the use of double-sided tape. Indeed, the entire outer surface of the assembly, consisting of the cylinder and the sleeve, is sticky and adherent to permanently, allowing you to directly attach printing plates. No prior operation of positioning and fixing a double-sided adhesive is therefore not necessary.

Furthermore, after their use, the plates can be easily removed from the outer surface of the sleeve for use higher.

This sleeve has a much lower cost price to that of double-sided adhesives, thanks to specific manufacturing.

We can also note that the continuity of the sleeve according to the invention eliminates the drawbacks related to the use of fastening means comprising joints. Indeed, the presence of joints leads conventionally printing defects and therefore losses of paper.

Advantageously, the sticky material and permanently adherent is based on polymers.

Preferably, this material is a photopolymer reticle.

The total thickness of the sticky materials and permanently adhering is, preferably, between 10 and 500 µm (microns).

Furthermore, the support of the sleeve according to the invention is advantageously compressible.

• placer un support de forme sensiblement cylindrique dans une machine d'enduction annulaire et à
• mettre en action ladite machine pour obtenir le dépôt d'au moins une couche d'un matériau collant et adhérent de façon permanente.

The invention also relates to a method for obtaining a sleeve as described above, this method consisting in:

• place a support of substantially cylindrical shape in an annular coating machine and
• putting said machine into action to obtain the deposition of at least one layer of a sticky and permanently adherent material.

Preferably, the support is arranged vertically in said machine, the latter comprising a container ring containing said material and placed around said support, the support and the container being animated by a relative movement of vertical translation to achieve depositing said layer on the support.

Furthermore, when the material deposited is polymeric type, and in particular a photopolymer, the method also consists in carrying out a crosslinking of said material.

• la Figure 1 est une vue en coupe d'une machine à enduction annulaire et verticale et
• la Figure 2 est une vue schématique d'une machine d'application du matériau par projection.

The invention will be better understood and other objects, advantages and characteristics thereof will appear more clearly on reading the description which follows and which is given with reference to the appended drawing, in which

• Figure 1 is a sectional view of an annular and vertical coating machine and
• Figure 2 is a schematic view of a machine for applying the material by spraying.

Reference 1 designates means for holding a support 2 substantially cylindrical, in a position vertical. These means 1 may in particular consist of a cylinder.

The support 2 is in particular made of a material composite like an epoxy resin matrix reinforced by fibers.

The machine also has a tank ring 3 which contains a sticky and adherent material permanently.

In the example illustrated, the support 2 is fixed and the machine comprises means 5 associated with the container 3 to move it vertically or along axis 20 support 2.

Of course, one could also provide a machine with a fixed annular container 3 and means to move the support 2 along its axis 20.

The means of translation of the annular container 3 are for example constituted by two nuts 6,7 fixed to the container 3, in diametrically opposite positions, each of these nuts being designed to cooperate with a threaded rod 8.9. Furthermore, appropriate means 10, 11 are provided to drive each of these rods threaded 8, 9.

The coating of the support 2 is carried out by ordering the drive means 10, 11 of the threaded rods 8, 9, so that the annular container 3 moves along axis 20, for example from top to bottom.

The annular container 3 is designed to deposit, on the support 2, a layer of the sticky material and adherent it contains, the thickness of which is included between 10 and 250 µm (microns). It is of course possible to repeat the operation to increase the total thickness of the sticky materials on the support 2.

This material is advantageously based on polymers.

It should therefore be cross-linked.

This is why, in the example illustrated on the figure, means 12 are provided to ensure the crosslinking of the polymer deposited on the support 2.

As an example, we can cite the materials following: polymers based on carboxylated nitrile, polyisoprene, acrylic resin, silicone, polychloroprene, ethylene vinyl acetate, butyl and polyurethane.

Cross-linking can be achieved by different means, in particular by exposure to UV light in the photopolymers, or by application of heat.

After crosslinking, these materials have a sticky, allowing the removable fixing of printing plates, which is characterized by a "sticky" or "tack" expressed in g / cm and measured for example on a MONSANTO brand device and of the "TELTAK" type with procedures known per se. The values of "sticky" corresponding to adhesives conforming to the invention are typically included in a range of about 50 to 500 g / cm.

In this range of values, a plate previously fixed on a support, can be removed without part of the adhesive layer remains fixed on the plate.

Of course, the crosslinking of the polymer is not necessarily performed in the induction machine itself, but this mode of implementation presents obvious advantages.

It can also be noted that the coating process annular allows the application of layers of material whose thickness is relatively thin.

The sticky and permanently adherent material which is deposited on the support 2 is a cost relatively high. Thus, the possibility of applying relatively thin layers of material reduces the cost price of the sleeve according to the invention, by compared to known fixing means and in particular the double-sided adhesives.

This is particularly true for materials of the photopolymer type which are of cost price Student.

The filing of sticky and permanently adherent material could also be produced by projection, as in painting, or by any other appropriate means. Figure 2 illustrates schematically a projection installation of the sticky and adherent material on the support cylinder 2 likely to be rotated, as is indicated by arrows. The material is sprayed onto the outer surface of cylinder 2 by a head projection 14 movable along a device guide 15 extending parallel to the axis of the support, under the effect of a control device 16. Such a device is known per se and need not be explained in more detail.

The processes which have just been described allow therefore to obtain a sleeve comprising a form support substantially cylindrical and whose outer surface is covered with a sticky material and adheres so permed.

Printing plates can then be attached anywhere on its outer surface and this, directly.

It is therefore no longer necessary to carry out prior operations of positioning means fixing, like double-sided adhesive strips.

This therefore considerably reduces the time for implementation and cost of labor.

Furthermore, when it is necessary to withdraw the printing plates, this removal is carried out without part of the adhesive remains attached to the plates printing. There is therefore no need to a subsequent plate cleaning operation for re-use.

In addition, the outer surface of the sleeve is not damaged, and other printing plates may subsequently be fixed therein in a removable manner.

In the examples that were previously described, the sleeve has only one layer of material sticky and permanently adhered. The sleeve can have different layers, applied successively, made or not with the same material sticky and permanently adhered.

The application of several successive layers on the support, during the manufacture of the sleeve according to the invention can make it possible to obtain a thickness specific performance. In this regard, different materials can be used in based on their physical properties, particularly in terms of hardness, chemical resistance or even stickiness.

Furthermore, the support of the sleeve according to the invention can be realized in a compressible material to improve the quality of printing.

Finally, throughout the description, only printing plates were mentioned, but the sleeve according to the invention could also be used for fixation of rotogravure plates, letterpress plates, offset plates or various films.

The reference signs inserted after the technical characteristics appearing in the claims are intended only to facilitate the understanding of these and cannot limit them the scope.

Claims (10)

1. An endless sleeve, including at least one substantially cylindrical support (2) whose exterior surface is covered with at least one layer of a permanently adherent and tacky material taking the form of an endless layer, wherein said sleeve is adapted to be mounted on a support cylinder and its exterior surface enables the removable fixing by adhesion of printing plates.
2. A sleeve according to claim 1, wherein said permanently adherent and tacky material is based on polymers.
3. A sleeve according to claim 2, wherein the material is a cross-linked photopolymer.
4. A sleeve according to any one of claims 1 to 3, wherein the total thickness of the tacky and adherent materials is from 10 µm to 500 µm (microns).
5. A sleeve according to any one of claims 1 to 4, wherein the support is compressible.
6. A method of obtaining a sleeve according to any one of claims 1 to 5, consisting in producing the layer of permanently adherent and tacky material by application of the adherent and tacky material to the exterior surface of the support.
7. A method according to claim 6, consisting in:

   placing a substantially cylindrical support (2) in an annular coating machine, and

   starting up said machine to deposit at least one layer of a permanently adherent and tacky material.
8. A method according to claim 7, wherein the support (2) is disposed vertically, the machine comprises an annular container (3) containing said material and placed around the support, and said support and said container are moved in translation relative to each other to deposit said layer on the support (2).
9. A method according to claim 7 or claim 8, wherein the material deposited on the support is of the polymer type, and in particular a photopolymer, the method further consisting in cross-linking said material.
10. A method according to claim 6, wherein the layer of adherent and tacky material is obtained by spraying the adherent and tacky material onto the exterior face of the support.

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