Patent Description:
In the known animal leathers, hereinafter more briefly leathers, we can recognize a more valuable outer layer or "flower" and an inner or less valuable layer or "crust". The lower value of the crust compared to the flower is linked both to aesthetic reasons, since the crust generally has a less uniform color than the flower, and to tactile reasons, since the crust is rougher than the flower.

Given the lower quality of the crust compared to the grain, it has a lower market value, and is less advantageous to process and market.

In order to improve the properties of the crust, so as to increase its attractiveness on the market, it has already been proposed to apply on its surface a coating layer of enhancing material, generally made of polyurethane, or other polymeric materials. This enhancing layer can have better optical properties (color, luster) and/or morphological (smoothness, elasticity, portions in relief) than the split, and such as to make it suitable for the production of high-end and/or luxury items.

The same method can also be used to associate enhancing layers with other materials such as, for example, the grain, or eco-leather (i.e. leather processed according to eco-sustainable methods) in order to modify its surface properties, such as color, softness.

In the step of applying the enhancing layer to the leather, which in itself does not have a proper consistency sufficient for its handling, it is generally applied to a sheet or to a support strip, generally made of suitably treated paper, which in industry tanning is defined as "release paper" and this term will also be indicated in this description, regardless of whether it consists of paper or other material suitable for the purpose.

It is also known that in order to couple the enhancing layer to the surface of the crust or of the leather in general, a layer of glue is spread on the surface itself, to which the enhancing layer, already joined to the release paper, is then made to adhere. Subsequently, the multilayer obtained by coupling the crust to the enhancing layer combined with the release paper, is heated in order to dry the adhesive and create a stable union between the two, before causing the release paper to detach from the leather.

This heating is usually obtained by passing the multilayer, in which the enhancing layer is arranged above and the leather is arranged below, through a heated environment (in practice through an oven) in which the multilayer itself is heated for a time sufficient to cause the complete drying of the adhesive, which before the heating process had a water content of approximately <NUM>-<NUM>% by weight.

However, this method is not fully satisfactory as the humidity, which is released by the adhesive in the form of water vapor and would tend to rise naturally upwards, given its lower density compared to the surrounding air, remains trapped below the enhancing layer and of the release paper, and more particularly between the glue and the enhancing layer, which is usually made of waterproof material. At the same time the passage of steam through the crust is prevented by the direction of the temperature gradient, which tends to cause the steam to rise upwards.

In turn, the stagnation of humidity below the enhancing layer can cause the formation of halos, which lead to defects, especially visual defects, incompatible with the marketability of the product.

Furthermore, the so-called "heat batteries" are used in the known treatment furnaces for the finishing of splits and leathers in general, which basically consist of pipes filled with a diathermic fluid (for example water or steam or mineral oils) heated to high temperature in a special boiler and associated with suitable radiators that heat the air inside the oven.

However, this method is not fully satisfactory since the thermal inertia of the furnace is very high due to the need to heat or cool all the air present inside the furnace and, even before that, the diathermic fluid. Therefore, in the event that it is necessary to vary the processing temperature inside the oven (for example due to the variation of the materials used (release paper, enhancing layer, glue, etc.), or the variation in the size of the splits to be ennobled), it is necessary to wait a long time, in some cases even many hours, before being able to resume processing, with a consequent undesirable increase in operating times.

In particular <CIT> and <CIT> both show a solution in which the strip to which the enhancing layer has been applied, to which, in turn, a leather has been associated, is inserted inside an oven to in order to allow the strip to dry.

These solutions are not fully satisfactory as an oven by definition provides for heating the air present in an environment in order to heat the objects it contains, and this entails enormous inertia on the part of the machinery.

<CIT> describes a production method for a leather garment which involves coupling the leather with a covering layer and passing said multilayer through a pair of heated rollers.

Also this solution is not fully satisfactory since the heating takes place under pressure, which involves a deformation of the coating layer.

The object of the invention is to propose a method that can be used for the processing of leathers and more particularly a method of applying an enhancing layer to the splits of leathers and leathers in general.

Another object of the invention is to propose a method capable of eliminating the drawbacks encountered in the known art and indicated above.

Another object of the invention is to propose a method of simple and rapid implementation.

Another object of the invention is to propose a method which can be implemented with low costs.

Another object of the invention is to propose a method which reduces the risk of obtaining a defective product.

Another object of the invention is to propose a method which allows to dry an ennobled crust more quickly and effectively.

Another object of the invention is to propose a method which allows to obtain an embossed product.

Another object of the invention is to propose a method that can be implemented with simple modifications of traditional machines and systems.

Another object of the invention is to propose a machine that can implement the method.

Another object of the invention is to propose a machine that can be inserted in processing lines in substitution of traditional machines to obtain products of superior quality.

Another object of the invention is to propose a modular machine to be installed in processing lines in the configuration suitable for satisfying the needs posed by the type and characteristics of the products to be processed.

All these purposes, either individually or in any combination thereof, and others which will result from the following description, are achieved, according to the invention, with a method for the processing of animal leathers and preferably for the enhancing of animal leathers as defined in the claim <NUM> and with a machine for carrying out the method as defined in claim <NUM> and with a production line according to claim <NUM>.

The present invention is further clarified hereinafter in some of its preferred embodiments reported for purely illustrative and non-limiting purposes. with reference to the attached drawing tables, in which:.

As can be seen from the figures, the machine <NUM> for carrying out the method according to the invention is designed to work on leathers coming from an upstream processing station, not shown.

The method and the machine will be described below in their embodiment for processing leathers. Hereinafter with "leathers" we mean semi-finished products of animal origin made of leather (both in the most precious part, also called "flower", and in the less precious part also called "crust"), or leather, or eco-leather, where with eco-leather are articles made with animal leather processed according to eco-sustainability criteria.

Preferably the machine <NUM> according to the invention is configured to ennoble the splits.

In any case, the machinery according to the invention is provided with an inlet feeder strip <NUM>, on which the leathers <NUM> to be ennobled are placed in sequence, already treated on their upper surface with a layer of glue <NUM>, which can consist of a chemical substance in a liquid and/or viscous state, or in any case with high humidity.

A layer <NUM> of enhancing material is intended to be made to adhere to the layer of glue, which in itself is traditional and consists, as stated, of polyurethane or other polymeric material.

The glue <NUM> must have characteristics of compatibility both with the leather <NUM> and with the enhancing layer <NUM> and must ensure the irreversible bond between the two. For example, it can be advantageously constituted by polymeric materials, such as for example polyurethane, or in any case materials that have a high affinity both with the leather <NUM> and with the material that makes up the enhancing layer <NUM>.

It is appropriate that the enhancing layer <NUM>, which by its nature it does not have a proper consistency suitable for its handling, whether applied on a support or carrier layer, preferably consisting of a continuous strip of release paper <NUM>, generally used for these applications. Advantageously, the enhancing layer can be added with suitable dyes and/or expanding agents, and preferably with at least one material configured to allow it to detach from the release paper strip once the processing is finished, as will be clear later.

The bond between the enhancing layer <NUM> and the continuous strip of release paper <NUM> can be obtained initially thanks to the viscosity of the material that forms the enhancing layer when it is still in the viscous layer, and subsequently thanks to the drying of the enhancing layer itself, and this constraint is sufficient to prevent the same enhancing layer from being dispersed during the process. Conveniently, thanks also to the presence of release materials, at the end of the processing it is possible to remove the material that forms the enhancing layer <NUM> from the release paper <NUM> and reuse the latter.

It is preferable for the release paper <NUM> to have portions in relief, suitable for creating recesses on the external surface of the enhancing layer <NUM> when this is coupled to the leather <NUM>, according to a known embossing process.

The machine <NUM> according to the invention comprises a chamber <NUM>, which has an essentially parallelepiped shape and defines inside it a closed environment in which the method according to the invention is implemented. The chamber <NUM> preferably presents on two opposite vertical walls <NUM>, <NUM>' by two pairs of overlapping openings facing each other. More particularly, two superimposed openings <NUM>,<NUM> are provided on a vertical wall <NUM> of the chamber <NUM> and two other superimposed openings <NUM>', <NUM>' are provided on the opposite vertical wall <NUM>', which face the previous openings <NUM>,<NUM>.

The upper openings <NUM>, <NUM>' are intended for the passage of the upper portion of the continuous strip of release paper <NUM>, which comes from a station upstream of the processing line, passes through the chamber <NUM> and then exits from the opening <NUM>', while the openings <NUM>, <NUM>' are intended for the passage of the lower portion of the continuous strip of release paper, which after exiting the upper opening <NUM>' is wound <NUM>° around the upper roller <NUM> of a pair of coupler rollers <NUM>, <NUM>' and reenters the chamber <NUM> through the lower opening <NUM>', passes through the chamber <NUM> again in the opposite direction and passes from this through the lower opening <NUM>.

It is preferable that the dimensions of these openings <NUM>,<NUM>', <NUM>,<NUM>' are just sufficient for the passage of the release paper strip <NUM> with the materials adhering to it, in order to minimize the exchange of air inside the chamber <NUM>.

Inside the chamber <NUM>, means can be advantageously provided for support and movement of the release paper strip <NUM>. They can comprise a plurality of rollers <NUM>, <NUM>', which can respectively support the upper and lower stretches of the release paper strip <NUM> or a conveyor belt.

According to the chosen embodiment, the rollers <NUM>,<NUM>' can be idle or partially motorized. Furthermore, the rollers <NUM>, <NUM>' can be more or less close to each other: if no conveyor belt is associated with them, it is preferable that they are more close to each other, while if a conveyor belt is associated with them it is possible to keep them more spaced apart. This conveyor belt, if provided, is preferably of the mesh type, and preferably is made of Kevlar, in order to withstand high temperatures, as will be clarified below.

The movement speed of the rollers <NUM>, <NUM>' inside the chamber <NUM> (and therefore, similarly and more generally, that of the release paper strip <NUM>) can be adjusted by the operator according to the materials to be treated and the operational needs and generally it must allow the working cycle inside the chamber <NUM> to be completed in a time comprised between <NUM> seconds and <NUM> minutes, and preferably comprised between <NUM> and <NUM> minutes.

Inside the chamber <NUM> there is also provided a heating apparatus which comprises a plurality of lamps <NUM> (first lamps) arranged in such a way as to heat the lower portion of the release paper strip <NUM> directly from above in order to allow the evaporation of the moisture present in the glue layer <NUM> interposed between each leather <NUM> and the enhancing layer <NUM>, as will be seen better below.

Conveniently, in practice no contact may occur between the heated elements (the lamps <NUM>) and the enhancing layer.

The lamps <NUM> are of the infrared type and are configured in such a way as to send the infrared radiations generated by them directly on the upper surface of the lower portion of the release paper strip <NUM>, i.e. the surface opposite to that which has the enhancing layer <NUM> applied, to the order to heat it directly by radiation.

Advantageously, said lamps <NUM> can emit radiations mainly comprised in the medium IR, and preferably the peak of the emitted radiations has a wavelength substantially comprised between <NUM> and <NUM>. It is preferable for said lamps to have a reflector, in order to increase the luminous intensity radiated towards the release paper strip <NUM>.

In particular, said lamps can be configured to send infrared light radiation directly on the continuous support strip <NUM>, and in particular on the surface of the support strip <NUM> which is not coupled to said enhancing layer <NUM>.

In practice, said lamps <NUM> can constitute a lighting apparatus configured to send infrared light radiation directly on the continuous support strip <NUM>, and in particular on the surface of the support strip <NUM> which is not coupled to said enhancing layer <NUM>.

Furthermore said first lamps <NUM> can be provided with a grid <NUM> configured to separate the warm portion of the lamp from the surrounding environment, so as to prevent accidental contact of some element, and in detail of the release paper, with the hot portion of the lamp <NUM>.

Inside the chamber <NUM> there can also be leveling rollers <NUM>, positioned above the lower portion of release paper strip <NUM>, at a lower height than that of the first lamps <NUM>, and configured to keep the portion substantially horizontal. In this way it is possible to prevent the lateral edges of the release paper strip <NUM> from lifting during the heating process, rileatherg contact with the lamps <NUM> and generating fires.

Depending on the performance required of the machine according to the invention, the infrared lamps <NUM> can be distributed homogeneously, or they can be arranged in such a way as to generate a temperature gradient between the initial part and the final part of the lower section of the release paper inside the chamber <NUM> and more specifically a direct temperature gradient in the direction of the advancement of the strip itself. In this way it is possible to obtain a more homogeneous drying of the glue <NUM> since it is possible to obtain the drying of even the innermost and less exposed layers of the glue <NUM>.

This temperature gradient can be obtained by reducing the distance between a lamp <NUM> and the subsequent in the direction of the advancement of the strip <NUM>, or by reducing the distance between the lamps <NUM> and the strip <NUM>, again in the direction of the advancement of the strip itself.

In an advantageous embodiment of the machine according to the invention, the lamps <NUM> can be configured to maintain the temperature of the upper surface of the release paper strip <NUM> between about <NUM> and <NUM>, and preferably between <NUM> and <NUM>. This temperature can advantageously be measured by means of a suitable measuring device <NUM>, constituted for example by a pyrometer. Alternatively, the temperature can be measured by positioning a first temperature probe near the lower portion of the release paper strip <NUM>, so as to detect the temperature of the air adjacent to the upper surface of this portion and then be able to deduce the surface temperature. of the release paper strip <NUM>.

Conveniently, the temperature of the lower surface of the leathers <NUM>, which adhere to the overlying release paper strip <NUM>, can be measured for example with a suitable measuring device <NUM>, also constituted by a pyrometer. Alternatively, the temperature can be measured by positioning a temperature probe near the lower surface of the lower section of release paper strip <NUM>, in order to obtain a detection of the temperature of the air adjacent to the lower part of it and to be able to deduce the temperature of the surface of the strip itself.

The infrared lamps <NUM> can be advantageously arranged to keep the temperature of the lower surface of the leathers <NUM> at a lower value of a few degrees centigrade, in particular between about <NUM> and <NUM>, and preferably between about <NUM> and <NUM>, and more preferably between about <NUM> and <NUM> with respect to the temperature of the upper surface of the release paper strip <NUM>.

In this way it is possible to create a temperature gradient with decreasing values from the enhancing layer <NUM> towards the leathers <NUM> which, being transpiring, allow the humidity evaporated from the glue layer <NUM> to escape from the lower part of said leathers <NUM>.

This is not possible using the heating means according to the state of the art, as these provide for the heating of the whole mass of air contained in the chamber <NUM>, and therefore the leather and the support strip <NUM> are substantially at the same temperature.

Advantageously, in this way the moisture that evaporates from the glue layer <NUM> can remain trapped inside the leather <NUM>, from which it will come out at a later time. Furthermore, the humidity that was deposited inside the enhancing layer <NUM> and/or, albeit to a minimum extent, also inside the release paper <NUM>, or more particularly on the lower surface of the enhancing layer <NUM>, would be rapidly re-evaporated.

In this way a net flow of humidity is obtained which from the glue <NUM> is directed towards the leather <NUM>.

A second group of lamps <NUM> (second lamps) can also be conveniently provided, which have the function of heating the upper portion of the release paper strip <NUM> during its passage from the upper inlet opening <NUM> to the upper outlet opening <NUM>' in order to at least partially dry the enhancing layer <NUM>, so as to ensure its adherence to the release paper strip <NUM>. Conveniently the second lamps <NUM> can be configured (i.e. sized) in order to substantially heat the entire chamber <NUM>.

The machine <NUM> according to the invention can also include a dehumidification apparatus, configured to reduce the humidity present inside the chamber <NUM>. It includes one or more dehumidification units <NUM>, preferably configured to suck air from inside the chamber <NUM>, to reduce its moisture content and/or to vary its t emperature, for example by means of suitable thermal cycles, and to subsequently reintroduce it, by means of suitable pipes, into the environment from which it was taken. Alternatively, the dehumidification units <NUM> can be configured simply to extract air from inside the chamber <NUM> and to discharge it outside.

The machine <NUM> according to the invention can preferably have a modular structure, in order to possibly be combined with similar machines, preferably in series, in order to vary the potential of the resulting plant, according to requirements. The machine of <FIG> is represented with the union in series of two aligned modules, each equipped with its own dehumidification unit <NUM>, and globally defining a single treatment chamber <NUM>.

The operation of the machine <NUM> now described is as follows:
The leathers <NUM>, placed on a conveyor belt <NUM> and already presenting, on their upper surface, a layer of glue <NUM>, are continuously transferred to a coupling station preferably comprising a pair of counter-rotating rollers <NUM>,<NUM>", of which the upper roller <NUM> also constitutes the return roller of the release paper strip <NUM>. In fact, this strip, which is already coupled with the enhancing layer <NUM> and after entering with its upper section through the the upper inlet opening <NUM> in the chamber <NUM> and having been heated by the second infrared lamps <NUM> has escaped through its upper outlet opening <NUM>', is wound around the upper coupler roller <NUM>, which also constitutes a deflection roller for the strip itself, and predisposes it to re-enter the chamber <NUM> through the lower inlet opening <NUM>' of the latter.

In correspondence of the contact area between the two coupler rollers <NUM>,<NUM>', the pressure coupling takes place between the leathers <NUM>, transported by the conveyor belt <NUM> and the enhancing layer <NUM> already coupled to the release paper strip <NUM>. From the two coupling rollers <NUM>,<NUM>' therefore a composite strip comes out which comprises in order, starting from the top downwards, the release paper strip <NUM>, the enhancing layer <NUM> and a sequence of leathers <NUM>, each kept adherent to the enhancing layer <NUM> by the layer of glue <NUM>, previously spread on the leather itself.

Inside the chamber <NUM>, the composite tape, which has entered through the inlet opening <NUM>', is heated directly above by irradiation from the first lamps <NUM>. Furthermore, the air present inside the chamber <NUM> (and consequently, the composite tape as a whole) can be heated by means of suitable heat pumps and/or second lamps <NUM>. In particular, for example, suitable ducts can be present which can be the same or different from those of the dehumidification units <NUM>, which suck the heated air from said second lamps <NUM> into the upper portion of the chamber <NUM>, and re-inject it at the leathers <NUM>, in the lower portion of said release paper strip <NUM>. Advantageously in the case in which the air drawn from the the upper part of said chamber <NUM> is too hot, it is possible to mix it with air taken from the surrounding environment in order to reduce its temperature.

With an appropriate sizing and appropriate adjustment of the first lamps <NUM> it is possible to generate a direct temperature gradient from the release paper strip <NUM> to the leathers <NUM>, so that the moisture desorbed by the glue <NUM> migrates towards the leathers <NUM> instead of towards the enhancing layer <NUM> and release paper strip <NUM>, which are waterproof. This allows a rapid and homogeneous desorption and/or removal of the humidity still present in the glue <NUM>.

As mentioned, the machine <NUM> can be installed inside a processing line for animal leathers and in particular inside a line configured to couple a protective layer and/or an enhancing layer <NUM> to a leather <NUM>.

In <FIG> illustrates, by way of example, a line <NUM> comprising a spreading station <NUM>, to which the leathers <NUM> to be ennobled have been fed manually or with suitable loaders.

In the spreading station <NUM> on each of the leathers <NUM> a layer of glue <NUM> is spread in a traditional way, which for example consists of polyurethane or its composites and has a weight preferably comprised of <NUM>-<NUM> grams per square foot, and preferably <NUM>-<NUM> grams per square foot.

Downstream of the spreading station <NUM>, the line <NUM> can comprise a pre-drying station <NUM> configured to perform a partial drying of the glue layer <NUM> previously spread on the upper surface of the leathers <NUM>. This pre-drying station <NUM> can comprise a plurality of heated rollers, or jets of hot air, or the like. At the exit of the pre-drying station, the quantity of humidity contained in the glue can advantageously be between <NUM> and <NUM>% by weight with respect to the glue.

Line <NUM> also includes a station for coupling the enhancing layer <NUM> with the release paper strip <NUM>, before the multilayer formed by the two is made to enter the chamber <NUM> through the upper inlet opening <NUM>. Being a traditional technique, for simplicity this station has been simply indicated with the reference <NUM> in the drawings.

The production line <NUM> then comprises a station <NUM> for coupling the enhancing layer <NUM> to the leathers <NUM>. It essentially comprises the two already described coupling rollers <NUM>,<NUM>', which advantageously can be pressed against each other in an adjustable manner, in order to be able to control the pressure with which the enhancing layer <NUM> is made to adhere to the leathers <NUM>, and can also be heated in order to obtain a better coupling between the enhancing layer <NUM> and each leather <NUM>.

Finally, the line <NUM> it comprises, downstream of the chamber <NUM>, a detachment station <NUM>, in which the separation of the leathers is effected, having applied on their upper surface the enhancing layer <NUM> from the release paper strip <NUM> carrying the enhancing layer applied in the parts not coupled to the leathers.

The description now made provides that the leathers <NUM> are made to adhere at the bottom to the lower portion of a multilayer strip closed in a ring and comprising in this section at the top the continuous support or carrier strip <NUM>, consisting for example of release paper, and at the bottom the enhancing layer <NUM>. The invention also provides for different configurations of the machine <NUM> for carrying out the method, and in particular, in a different embodiment not shown, it provides that the individual leathers <NUM>, made to advance by a conveyor belt and presenting, on their upper surface, a layer of glue, are overturned onto an underlying multilayer tape comprising the continuous strip of release paper at the bottom and the enhancing layer at the top.

In another embodiment, illustrated in <FIG>, the machine is similar to that illustrated in <FIG> but unlike this, it provides that the rollers <NUM>' which in the previous embodiment supported the lower portion of release paper strip <NUM> and the enhancing layer <NUM> adhering to it are replaced by a conveyor belt <NUM> which, as mentioned, is preferably made of kevlar, in order to withstand the high temperatures involved.

From what has been said it is clear that the method according to the invention, which envisages creating in the leather <NUM>, which is coupled to the enhancing layer <NUM>, a temperature gradient that causes the moisture to escape through the leather itself, profoundly modifies the traditional technique, as it allows to obtain a high quality product starting from inferior quality products, such as animal leathers, and in this way to eliminate the negative aspects that the traditional technique presents.

Furthermore, the method according to the invention can be used by adopting simple modification interventions to the currently existing equipment and therefore obtaining optimal results with somewhat limited installation costs.

Claim 1:
Method for the finishing of leathers, which involves the coupling to the surface of the leather (<NUM>), by means of a layer of glue (<NUM>) previously deposited on the surface of said leather (<NUM>), of an enhancing layer (<NUM>) previously applied to a continuous support strip (<NUM>), said layer of glue (<NUM>) being dried inside a chamber (<NUM>), said method being characterized in that the surface of said continuous support strip (<NUM>) that is not in contact with said enhancing layer (<NUM>) is heated by direct infrared radiation.