EP0881098A1 - Sleeve for printing or analoguous cylinder and method to fasten said sleeve - Google Patents

Abstract

The roller has an outer printing or coating layer (1) and a series of linked concentric layers (2, 3, 4), at least one of which contains a material conferring thermo-shrink properties. The thermo-shrink layer can be the outer printing or coating layer, over a compressible layer (2) and a supporting layer (3), and it is made from a material based on polyethylene, PVC, polyamide, propylene, polyvinylidene fluoride, or other polymers having a crystalline level of 10 - 60 per cent.

Description

The main subject of the present invention is a sleeve, removable or not, for a machine cylinder printing, coating, embossing, expressing, or in general finishing of any substrate.

It also relates to a process for implementing this sleeve on the aforementioned cylinder.

We have already offered sleeves for a long time multilayers with various structures and intended for equipping the cylinders with offset printing machines especially.

Generally, these sleeves consist of a plurality of associated concentric layers, namely basically an outer print layer or lithographic and one or more underlying layers likely to provide the desired print quality on a substrate such as for example paper.

However, the known sleeves have a certain number of constraints in terms of their manufacture and their usage.

They must be custom-made according to the dimensions of the chucks or cylinders of the machines on which they must be mounted. This requirement often requires the use of specific manufacturing, and the manufacturing time is more or less long depending on the complexity of structure of the multilayer sleeve, so that in total manufacturing costs are relatively high.

Furthermore, the known sleeves cannot adapt to highly variable conditions of use industrial and very variable diameters of cylinders fitted to printing machines or finishing of substrates in general.

Therefore, the user, to equip the cylinders machine or to replace worn sleeves on these cylinders is obliged to proceed with the purchase as many sleeves as cylinder diameters, which is not advantageous for him financially especially.

Also, the present invention aims to solve the above problems by proposing a sleeve that can be qualified as universal in the sense that it is adaptable to any cylinder diameter for a printing machine, coating or whatever.

To this end, the present invention provides a sleeve for printing, coating machine cylinder or analogous, comprising several concentric layers associated, namely an outer printing layer, coating or the like and one or more underlying layers participating in print quality or coating of any support, characterized in at least one of the layers of the sleeve is retractable heat to adapt to the diameter of the machine cylinder.

According to another characteristic of this sleeve, the heat-shrinkable layer is a layer having only the technical retraction function.

According to another embodiment, the heat-shrinkable layer at the same time constitutes a layer having a other function.

This heat-shrinkable layer may constitute volume about 10 to 50% of said layer having another function.

Thus, the heat-shrinkable layer can be integrated to an external printing, coating or analogous, to a compressible layer, to a layer support, or at least two of these three layers.

The sleeve according to this invention is further characterized in that the aforementioned heat-shrinkable layer is in one material based on polyethylene, polyvinyl chloride (PVC), polyamide, polypropylene or fluorinated polyvinylidene (PVDF).

According to yet another characteristic of this sleeve, the innermost layer of said sleeve may include on its external surface a hot-melt adhesive or a layer of self-adhesive polymer for bonding the sleeve after retraction, on the cylinder.

We will also specify here that the sleeve can be made up of several independent parts concentrically nested one of which is permanently on the cylinder and of which at least one other is removable and has at least one heat-shrinkable layer.

The sleeve of this invention can be interrupted following a generator and include a clasp for allow its mounting on the cylinder before heat-shrinking.

In this case, provision may be made for joining the sleeve on the cylinder at the clasp to make said functionally endless sleeve.

The sleeve with heat-shrinkable layer (s) according to this invention can constitute an offset printing sleeve or a flexographic printing sleeve.

In the latter case, it comprises, between a layer printing photopolymer and cell layer compressible, a barrier layer which forms a layer heat shrink.

This invention also relates to a method of setting up a sleeve meeting the above characteristics, on a cylinder of a printing, coating or analogous, characterized by heating the sleeve on said cylinder by means of an air convection system hot or microwave to activate the heat shrink layer.

So, after fitting the sleeve on the cylinder, said sleeve having a larger diameter than that of the cylinder, heating will provide retraction and tightening of the sleeve on the periphery of the cylinder, which sleeve can therefore be simply maintained by pressure against the cylinder or by gluing if the sleeve has an internal layer of adhesive.

But other advantages and characteristics of the invention will appear better in the description detailed which follows and refers to the attached drawings, given only by way of example, and in which:

Figures 1, 2 and 3 illustrate schematically and in cross section of sleeves for machine cylinder offset printing according to this invention.

Figure 4 is a schematic sectional view partial cross section of a printing sleeve flexographic.

Figures 5 and 6 illustrate schematically and in section partial transverse placement of a sleeve on a cylinder (figure 5) and the mounted position of the sleeve on this cylinder after heat-shrinking (Figure 6).

Figure 7 illustrates in cross section a sleeve according to this invention provided with a clasp shown with a schematically, and in a position ready to be fixed around a cylinder.

Figure 8 is an enlarged partial sectional view transverse of the sleeve in the fixed position around the cylinder and comprising a junction at the level of clasp to make the sleeve functionally free end.

We will first describe various realizations of sleeves offset printing with reference to Figures 1, 2 and 3.

In Figure 1, we see a three-layer sleeve, know an outer print layer or layer lithographic 1, a compressible layer 2 which can be made of cellular elastomer, and a support layer any 3 which will come into contact with the cylinder (no shown) in Figures 1, 2 and 3.

According to the invention, at least one of the layers 1, 2 or 3 is incorporated a material giving it a heat-shrinkable and constituting approximately 10 to 50% of this layer, by volume. In other words, the layer to which will be integrated said material will retain its its own function and to which will be added the heat-shrink function.

For this purpose, it is possible to use, for example, alloys of polymers whose heat-shrinkable phase has a rate crystallinity between 10 and 60%.

For example, the material in question could be integrated to layer 2 which will therefore be a compressible layer and heat shrink.

In the variant shown in Figure 2, which shows a multilayer sleeve with a structure comparable to that shown in Figure 1, we have shown in 4 a layer heat shrink which is an additional layer, that is to say a layer having only the function withdrawal technique.

This layer is interposed between the support layer 3 and compressible layer 2, but it might as well be interposed, without departing from the scope of the invention, between lithographic layer 1 and layer compressible 2. In the same spirit, we could perfectly provide two heat-shrinkable layers such as 4 between layers 1 and 2 respectively and layers 2 and 3.

The heat-shrinkable layer (s) 4, whether they are independent of the other layers (Figure 2), or whether they are integrated into one and / or the other of these other layers (Figure 1), are a material based on polyethylene, polyvinyl chloride (PVC), polyamide, polypropylene or fluorinated polyvinylidene (PVDF), or other polymeric materials having a rate of crystallinity between 10 and 60% in a range of useful temperature.

In Figure 3, we see a sleeve comprising a layer lithographic 1, a compressible layer 2, and a layer of hot-melt adhesive 5 which replaces the support layer 3. Of course, as described above, a heat-shrinkable layer (not shown here) may either be interposed between layers 1 and 2 for example is integrated into at least one of these two layers.

The adhesive layer 5 will allow, as will be described in detail below, gluing the sleeve, after retraction, on the cylinder which must be equipped with this muff.

We will also observe here that layer 5 can be also consisting of a layer of self-adhesive polymer.

It should be added here that, without going beyond the ambit of the invention, the sleeves shown in Figures 1, 2 and 3 could each have both kinds of layers heat-shrinkable, namely one or more layers 4 having only the technical function of withdrawal as well that one or more heat-shrinkable layers integrated into the minus one of layers 1, 2 or 3.

• une couche photopolymère 10 qui comporte généralement et comme connu en soi une semelle (non représentée) et une partie en relief constituant la partie imprimante ;
• une couche barrière 20 qui confère une certaine stabilité mécanique au manchon lors de la rotation et qui évite la migration des monomères de la couche photopolymère 10 vers l'intérieur du manchon ; et
• une couche compressible 30 formée d'un élastomère cellulaire.

FIG. 4 shows a flexographic printing sleeve which comprises, from the outside to the inside:

• a photopolymer layer 10 which generally comprises and as known per se a sole (not shown) and a raised part constituting the printer part;
• a barrier layer 20 which confers a certain mechanical stability on the sleeve during rotation and which prevents the migration of the monomers from the photopolymer layer 10 towards the interior of the sleeve; and
• a compressible layer 30 formed of a cellular elastomer.

The realization of the image in relief on the sleeve photopolymer preferably requires application on the outer surface of the photopolymer layer 10 of additional thin layers before exposure UV and its development. These layers, known per se, can be non-stick layers protecting the surface when in contact with the UV mask or one or more layers to generate the UV mask "in-situ" on the sleeve or layers of revelation of the image contrast or relevant combinations of these.

As for the offset sleeves illustrated in the figures 1, 2 and 3, one or more layers can be provided heat-shrinkable having only the technical function of retraction and interposed between layers 10 and 20, 20 and 30. This is how we have shown as an example on Figure 4 such a heat shrinkable layer 40 interposed between the barrier layer 20 and the layer fuel 30.

A heat shrinkable layer such as 40 could also be provided between layers 10 and 20.

Also, as described in connection with Figure 1, at least one of the layers 20, 30 could, in addition to its function its own, being a heat-shrinkable layer.

According to a preferred embodiment, it is the layer barrier 20 between the photopolymer layer 10 and the layer compressible 30, which will be made heat-shrinkable by incorporation of one and / or the other of the materials previously mentioned.

We will now describe the installation and assembly of the sleeve according to the invention with more reference particularly in Figures 5 and 6.

In these figures, there is shown schematically and partially a sleeve comprising a layer lithographic 1, a compressible layer 2, a layer heat-shrinkable 4 and a layer 5 of hot-melt adhesive or self-adhesive polymer.

It can be seen in FIG. 5 that the internal diameter of the multilayer sleeve is greater than the diameter of the cylinder 100, so that said sleeve can be easily threaded on cylinder 100.

We will then heat the sleeve in place on the cylinder using an air convection system hot or microwave for example (not shown), so that the heat shrinkable layer 4 will be activated and will firstly cause the sleeve to shrink on the cylinder 100 until it hugs its periphery external, and then its bonding on said periphery thanks to layer 5.

Of course, layer 5 could perfectly be omitted without departing from the scope of the invention, as has previously explained.

So, as we understand, the same dimension of sleeve can advantageously be adapted to various cylinder diameters.

The sleeves visible in FIGS. 1 to 6 are endless sleeves but we could perfectly realize a sleeve interrupted following a generator and comprising, as seen in Figure 7, a clasp 60 allowing its mounting on the cylinder 100 before heat shrink.

The clasp 60 could form a bead 61 susceptible to be clipped into a groove 62 to thus achieve the mounting the sleeve around the cylinder, as seen well in figure 8, after which the sleeve is, heated to retract and hug the periphery of the cylinder 100.

In figure 8, we also see that we could achieve, by heat fusion, a joining 63 of the sleeve on the cylinder 100 at the clasp 60 of so that finally we would have a sleeve functionally endless.

The interrupted sleeve could also, if necessary, be provided with a layer of hot-melt adhesive (not shown) on the contacting face with the machine 100 cylinder.

To make the sleeve heat-shrinkable according to this inventicn, we use a technique known per se proceed as follows:

The multilayer sleeve with either one or more independent or integrated heat-shrinkable layers to the other layers is obtained by extrusion and cut to the desired length.

Then the sleeve is preferably crosslinked and it is heats, which allows its radial expansion.

Then at an expansion rate corresponding to the diameter interior desired, the sleeve is cooled, which freezes its expanded form.

As described above, the sleeve can then be put in place on a cylinder of smaller diameter and heated which will cause its retraction and its mounting on the periphery of the cylinder.

Of course, the invention is by no means limited to described and illustrated embodiments which have not been given as an example.

This is how the sleeve of this invention could be made up of several independent parts concentrically nested one of which would be permanent on the cylinder and at least one of which would be removable and would include one or more heat-shrinkable layers.

Also, the sleeve of the invention finds multiple applications in for example printing flexographic, gravure printing, offset printing or for coating and varnishing applications.

This means that the invention includes all the equivalents techniques of the means described as well as their combinations if these are performed according to its mind.

Claims (8)

Sleeve for printing machine cylinder, coating or the like, comprising several layers associated concentrics, namely an outer layer printing, coating or the like (1, 10) and one or more several underlying layers (2, 3, 20, 30), characterized in that at least one of said layers (1, 2, 3, 10, 20, 30) is incorporated a material imparting heat shrinkability and constituting, by volume, about 10 to 50% of this layer so that it retains its proper function and which is added the heat-shrink function. Sleeve according to claim 1, characterized in that the heat-shrinkable layer constitutes at the same time an outer layer of printing, coating or the like (1, 10), a compressible layer (2, 30), a layer support (3) or at least two of these three layers. Sleeve according to claim 1 or 2, characterized in that the heat-shrinkable layer is made of a material based on polyethylene, polyvinyl chloride (PVC), polyamide, polypropylene, fluorinated polyvinylidene (PVDF), or other polymeric materials having a rate of crystallinity between 10 and 60%. Sleeve according to one of the preceding claims, characterized in that it is interrupted according to a generator and includes a clasp (60) to allow its mounting on a cylinder (100) before heat-shrinking. Sleeve according to claim 4, characterized by joining (63) of said sleeve on the cylinder (100) at the clasp (60) to make said sleeve functionally endless. Sleeve according to one of the preceding claims, characterized in that it constitutes a printing sleeve offset or flexographic printing sleeve. Sleeve according to claim 6, characterized in that that in the case where it constitutes a printing sleeve flexographic, it has, between a layer printing photopolymer (10) and a cell layer compressible (30), a barrier layer (20) which forms a heat-shrinkable layer. Process for fitting a sleeve according to one of claims 1 to 7 on a machine cylinder printing, characterized in that after the installation of the sleeve on a cylinder of smaller diameter, heating this sleeve on the cylinder by means of a system with convection of hot air or microwave to activate the heat shrinkable layer to cause retraction and mounting of the sleeve on the periphery of the cylinder.

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