WO2006100055A1

WO2006100055A1 - Method for the finishing of leather or a sheet-coated material and corresponding plant

Info

Publication number: WO2006100055A1
Application number: PCT/EP2006/002628
Authority: WO
Inventors: Giacomo Agosti
Original assignee: Cos.T.A. S.R.L.
Priority date: 2005-03-23
Filing date: 2006-03-22
Publication date: 2006-09-28
Also published as: ITVI20050081A1

Abstract

Method for the finishing of leather or a sheet-coated material (3) characterised by being continuous and to include the following operations: apply on a surface (2) of said moving leather (3) or sheet-coated material, at least one layer (4) substantially uniform of a finishing substance (5); print on at least one said layer (4) of said substance (5) the imprint of an embossed surface (6); transform at least one said layer (4) of said substance (5) into a finishing film (F) that substantially reproduces the superficial characteristics of said embossed surface (6).

Description

DESCRIPTION

METHOD FOR THE FINISHING OF LEATHER OR A SHEET-COATED MATERIAL AND CORRESPONDING PLANT

Technical field The invention refers to a method for the finishing of leather or a sheet- coated material, specially adapted to be applied to leather of type called grain and rough tanned or to textile and synthetic laminar-coated products also consisting of microfibres, or synthetic leather. Background Art As known in many sectors such as for example the furniture sector, clothing and footwear, natural leather is widely used as well as different materials that imitating the aesthetic aspect, aim to reduce the production costs improving some physical and mechanical characteristics. One among the various working processes to which the leather is submitted prior to its use, is the superficial finishing. Such process allows to establish some aesthetic characteristics of the treated leather and is applied generally to the less noble types of leather called rough tanned and grain. The known method substantially provides to apply on the surface of the leather to be treated, by appropriate means, one or more layers of a fluid polyurethane resin, with variable viscosity in relation to the type of product used and to the final result which is to be obtained. The leather is then dried making the solvents or the water contained in the treated product evaporate, in order to obtain a plastic film.

The evaporation is generally obtained sending the leather in a path inside a drying tunnel, where the temperatures do not exceed 90⁰C. The normal operation schedule, at this point can provide an additional eventual application of the same substance followed by the relative drying operation inside a tunnel.

The dried leather is then prepared for the following working called printing, which consists in applying an emulsion of anti-adhesive substances on the film, and in the hot-press, with a matrix, the surface of the film to be finished to give the leather an aspect as similar as possible to the model that is intended to reproduce.

Such printing work can be carried out with a hot plate press or with press cylinders.

In the first case the leather is transferred and placed manually by an operator onto the plane of the press, in order to present the film directed towards the movable and embossed plane of the press itself.

In the second case the leather is forced between two opposite rotating cylinders one of which and in particular that opposed to the film, presents the embossed surface.

In both cases the leather is submitted to a pressure and at a variable temperature in relation to the designs to be reproduced.

A first disadvantage of these methods is the high pressures together with high temperatures to which the leather is necessarily submitted.

This determines a reduction of the thickness of the leather, a compacting of the fibres and therefore a reduction of the natural proper softness of the leather.

Another disadvantage consists in the fact that to carry out such methods a sequence of operations is necessary, in series, on different machines, with the need of the intervention of one or more operators between one phase and the following one, which provide the charging of the leather, one by one for each operation. This considerably limits the speed of the entire production cycle considerably increasing production costs and therefore the total cost of the final product.

Another disadvantage consists in the fact that the presses are dangerous for the operator.

An additional disadvantage consists in the fact that the assigned operator by operating the press inhales the harmful vapours that the material emits during the thermoforming of the polyurethane resin, constituting the applied finishing film on the leather. Another disadvantage consists in the fact that all the leather is submitted simultaneously to hot pressing, for a prolonged time, prejudicing in such a way some important characteristics.

A further disadvantage is the total encumbrance of these finishing plants.

It is aim of this invention to overcome said drawbacks. It is in particular a first aim of the invention to propose a method for the finishing of leather or a sheet-coated material that can be continuously carried out, as well as a relative plant.

It is an additional aim to propose a method and a plant which allow to obtain a finished product with the same desired superficial finishing conserving the particular characteristics of the support made indifferently from a leather or a sheet-coated material in general.

It is another aim to propose a method and a plant which allow to cut down the number of necessary heat treatments for the obtainment of the finished product. It is an additional aim to propose a method that, with equal aesthetic characteristics of the finished product and with regards to the known methods, considerably reduces the thermal stress to which the leather or the sheet-coated material is submitted. It is another aim is to propose a method and a plant that allow to reduce the pressure to exert on the leather or on the necessary sheet-coated material for the obtainment of the finished product. A further aim is to propose a method that, with equal aesthetic characteristics of the finished product and as regards well-known methods, considerably reduces the mechanical stress to which the leather or the sheet-coated material is submitted. Another aim is to propose a method and a plant which allow to reduce, with respect to the known methods and plants, the times and the costs of production of such finished leather or sheet-coated materials.

An additional aim is to realize a plant that can be inserted, advantageously but not necessarily, in other already existing continuous productive lines. A further aim to realize a plant of easy management and configuration, which is reliable and that does not require particular maintenance.

Said aims are reached by a method for the finishing of leather or a sheet- coated material, advantageously but not exclusively leather of the type of said rough tanned and grain, in accordance with the characteristics of the main claim. Said aims are reached also by a plant for the finishing of leather or a sheet-coated material, advantageously but not exclusively leather of the type of said rough tanned and grain, in accordance with the features of claim 11. Advantageous realization features form the object of the dependent claims.

Advantageously the proposed solution allows to realize the continuous finishing and without the intervention of an operator. Still advantageously the proposed solution allows also to reduce the thickness of the film and realize a softer finished product with respect to products of a known type.

Still advantageously the plant able to realize the proposed method, presents a lower encumbrance compared to plants able to realize finished products of the traditional type.

Said aims and advantages will be better evidenced in the description of some preferred forms of execution of the invention, give to not limitative and indicative title, referring to the enclosed drawings, wherein: - Figure 1 represents schematically the operative phases of the method, object of the invention;

- Figure 2 represents schematically, the various phases of the proposed method, in its different formulation;

- Figure 3 represents a schematic view of a plant that realizes the method of the invention;

- Figure 4 represents a schematic view of a variant of the plant of figure 3;

- Figure 5 represents a schematic view of another variant of the plant of figure 3; - Figure 6 represents a schematic view of an additional plant of the invention.

In the following description reference will be made to the finishing method of leather. It is clear however that such method is applicable also for finishing any sheet-coated material having the support function, and consists for example of a natural or synthetic textile laminar product, an agglomerate of microfibres, and so on. In particular the continuous method for the finishing of leather or a sheet- coated material, will be now described referring to the illustrative scheme of figure 1. It provides substantially to apply on the surface 2 of a sheet-coated material consisting for example of leather 3 moving along a substantially rectilinear direction 8, at least one layer 4 substantially uniform of a finishing substance 5 and to print, on the layer 4 the characteristics (the imprint) of an embossed surface 6, while the leather 3 is always moving, realizing contextually the transformation of the substance 5 in the film F and therefore the product and/or finished leather 1.

Still according to the invention in fact while one proceeds to print the layer 4 of substance, contextually it provides to heat up the substance 5, for realizing the transformation in a finishing film F that reproduces substantially and steadily the embossed surface imprint or superficial characteristics 6.

It is observed that advantageously the application of one or more substance layers 5 and the embossing happen while the leather 3 advances, thus allowing to obtain a continuous working process. In the example of realization of the proposed method, represented schematically in figure 1 , the sheet-coated material consisting of, in the example, leather, is spread out on a conveyor belt 7 that makes it advance along a substantially rectilinear direction 8. Above such conveyor belt 10 application means 9 of the substance 5 including a plurality of spraying nozzles 91 are placed, supplied by a container of the substance 5. In other realizations such application means 9 include different deposition systems such as cylinder means, and/or doctor blade or equivalent, also of a known type. In this case, the substance 5 includes substantially a polyurethane resin opportunely diluted with suitable solvents or with other substances. Regarding the embossed surface 6 it is made up, in the represented example, of the surface of a rotating cylinder 10 that cooperates with a counter-cylinder 11 for pressing the leather 3.

Regarding the transformation of the layer 4 of the substance 5 in the film F, it is carried out, in this case and as previously said, by heating the said substance 5 and/or the leather 3 and/or the embossed surface 6 by means of not visible heating means. Such means operate, in this case, raising the embossed surface temperature 6 to a suitable value and depending on said substance 5 for causing the aforementioned reaction.

In this way, an elastic film F is obtained that reproduces the impressed morphologic characteristics in the embossed surface 6. In other realizations such transformation is obtained using catalysts and/or varying physical parameters that allow, on the basis of the substance used, the above-described transformation process. A first variant of the proposed method, shown in figure 2, is differentiated by the previous one because the embossed surface 6 belongs to an embossed belt 12, preferably closed, that is interposed between a press cylinder 13 and the leather 3.

This solution, allows advantageously to quickly change the impressed aesthetic characteristics on the sheet-coated material or the finished leather by simply replacing the belt 12. The belt 12 is preferably realized in paper but can in other realizations be indifferently made also with other materials.

A further variant of the proposed method differs from the previous ones because, besides the above-described operations, a further heating phase of the sheet-coated material or the leather 3 and of the polyurethane film F is provided, directed to facilitate the reticulating and/or the drying also partial and to further stabilize the finished product 1. A plant for the realization of a finished product 1 , obtained by a sheet- coated material or leather, also object of the invention is represented schematically in figure 3, where it has been indicated as a whole with the number 100. The plant 100 represented and described as follows, is advantageously of the continuous type and it can also be inserted in already existing productive lines.

In it, a charge zone 115 of the sheet-coated material and the leather 3 is identified, the application means of the substance 109, the means 116 able to print the desired superficial characteristics and a discharge zone 117.

At the charging zone 115 a conveyer assembly is present including a conveyor belt 118, that individuates a movable plane on which the leather to be finished 3 is placed. The conveyor belt 118, moved by power-operated rolls 119, moves the sheet-coated material or the leather to be finished 3 first towards the application means 109 of the substance 5 and then towards the following workstation.

With reference to the means 109 for the application of the substance 5, they include, in this case, a spraying group provided with one or more adjustable nozzles 109a.

As an alternative, such application means 109 can include a nebulizer that addresses the product on the surface of the leather to be finished 3 or a brush or a cylinder or doctor-blade system or equivalent systems of a known-type and consequently not described.

Regarding the substance 5, it includes, preferably, a polyurethane resin in aqueous solution and catalyzing substances that are stored in tanks not visible that supply the aforementioned application means 109.

With reference to the means 116, able to print the desired imprint, they include a pressing group similar to a calender including a power- operated press cylinder 110 having an embossed surface 106, cooperating with a counter-cylinder 111 , as well as heating means of heat said cylinders, not visible.

A further formulation of the plant of the invention, indicated as a whole with the number 200 in figure 4, is differentiated by the previous one because the embossed surface 206 belongs to an embossed belt 212. In particular, in the shown realization, such belt 212 is closed and is replaceable to allow to realize impressions having different forms and characteristics.

As an alternative it can be not closed and come from an unroller group 320, as represented in particular in figure 5, cooperating with a roller group 321. In this other executive variant the plant, indicated as a whole with 300 in figure 5, is differentiated from the previous one also because more application means 309 are present, placed aligned one after the other and alternated by a drying oven 322. Such plant 300 allows in such a way to realize multilayer material overimposed one over the other, before going on to the impression operation.

The same plant 300, differentiates from the previous realizations also because downstream of the embossed means 316, drying means of the finished leather 1 are provided, including a continuous oven 323 of the said tunnel type.

Such drying oven allows to further stabilize the finished leather 1 taking away the possible residual humidity. Figure 6 represents an additional example of a plant of the invention, indicated as a whole with the number 400 in which the roller group 421 of the belt 412 is placed near the discharge zone 417 of the finished product.

In such example we point out moreover how the leather 3 is kept in contact with the embossed belt also by means of rolls, for the whole section 430 and therefore for a greater lapse of time.

This advantageously allows to further consolidate the finished product.

In the section 430 moreover, heating units, not visible, are provided that contribute to the aforesaid consolidation of the product. An additional executive variant differentiates from the previous ones because the application means include also a unit for the detection of the geometric form of the surface 2 of the leather to be finished 3.

Such unit, substantially of a known type, includes systems for the acquisition and the processing of images, co-operating with a checking unit to command the activation and the deactivation of the application means, minimizing in such a way, the use of the applied substances.

Another example of realization of the invention provides that downstream of the application means and upstream of said drying means are placed, able to partially dry the substance layer before submitting it to the impression.

It is clear that the above-described arrangement of the groups is obviously indicatively given as the parts and the means which execute the various operations can be different, as well, they can be inserted in an any number inside of the plant.

In particular the number of application means of the substance, as well as the number of stations suitable to print the embossed surface characteristics, can vary in number.

It is observed, moreover, that between the various parts of the plant further devices or machines can also be placed, suitable to realize works or particular effects on the film and/or on the support, as well as on the obtained leather. The description of the working of the proposed plant is described as follows, referring to the first described plant 100 represented in figure 3.

The working of the plant 100 provides that on the leather 3 that advances along the rectilinear direction 130, one or more layers 4 of substance 5 is applied by means of the application means 109. The belt 118 then carries the leather 3 towards the heated press embossed cylinder 110 which, cooperating with the counter-cylinder 111 , realizes the film F simultaneously impressing the characteristics of the embossed surface 106.

The finished leather 1 is then conveyed towards the discharge zone 117 that advantageously can be the charging zone of a following workstation.

From what has been said it is clear that the method and the proposed plant allow to reach the prefixed aims.

In particular it is clear that the proposed solution allows to realize the finishing of leather or a sheet-coated material in general with a continuous process, increasing, as regards to known processes, the production speed and allowing the upstream and/or downstream insertion of other working stations. Although the invention has been described referring to the enclosed drawings, it can suffer modifications during the realization, all being included in the same inventive concept expressed by the claims set out below and consequently according to present invention.

Claims

1. Method for the finishing of leather or a sheet-coated material (3) characterised by being continuous and to include the following operations: - apply on a surface (2) of said moving leather (3) or sheet-coated material, at least one layer (4) substantially uniform of a finishing substance (5);

- print on at least one said layer (4) of said substance (5) the imprint of an embossed surface (6); - transform at least one said layer (4) of said substance (5) into a finishing film (F) that substantially reproduces the superficial characteristics of said embossed surface (6).

2. Method according to claim 1 , characterised in that said operation of transformation of said substance (5) into said finishing film (F) occurs by heating.

3. Method according to claim 1 , characterised in that said transformation is obtained using catalysts and/or varying physical parameters of said substance.

4. Method according to claim 1 or 2 or 3, characterised in that said operations of impression and transformation, happen contextually.

5. Method according to claim 1 or 2, characterised in that said operations of impression and transformation happen by hot calendering.

6. Method according to any of the previous claims, characterised in that said finishing substance (5) includes a polyurethane resin.

7. Method according to any of the previous claims, characterised in that said embossed surface (6) consists of the surface of a rotating cylinder

(10)

8. Method according to claim 7, characterised in that said rotating cylinder (10) cooperates with a counter-cylinder (11) for pressing said leather (3) or said sheet-coated material.

9. Method according to any of claims from 1 to 6, characterised in that said embossed surface (6) belongs to an embossed belt (12).

10. Method according to claim 9, characterised in that said embossed belt is closed.

11. Plant (100,200,300,400) for the finishing of leather (3) or a sheet- coated material characterised by having:

- a conveyer assembly on which said leather (3) or said sheet-coated material to be finished (3) is placed;

- application means (109) of at least one layer (4) substantially homogenous of a finishing substance (5) on a surface of said leather (3) or said sheet-coated material to be finished;

- means able to print the desired superficial characteristics to at least one said layer (4) of said substance (5).

12. Plant according to claim 11 , characterised by having moreover means able to transform at least one said layer into a finishing film (F).

13. Plant according to claim 11 or 12, characterised in that said application means (109) of said substance (5) include a spraying group and/or a nebulizer and/or a brush and/or a doctor-blade system and/or cylinder system.

14. Plant according to claim 11 or 12 or 13, characterised in that said conveyer assembly includes a conveyor belt (118), able to move said leather (3) or said sheet-coated material to be finished.

15. Plant according to any of claims from 11 to 14, characterised in that said means able to transform at least one said layer into a finishing film (F) include heating means.

16. Plant according to claim 11 and 12, characterised in that said means able to print the desired superficial characteristics onto at least one said layer (4) of said substance (5) and said means able to transform at least one said layer into a finishing film (F) include a pressing group similar to a calender.

17. Plant according to claim 16, characterised in that said calender group including a power-operated press cylinder (110) having the surface (106) embossed, cooperating with a counter-cylinder (111), and further comprising heating means able to heat up said substance (5) and/or said leather (3) or of said sheet-coated material and/or said embossed surface (6) for transforming at least one said layer (4) into a film (F).

18. Plant according to claim 11, characterised in that said means able to print the desired superficial characteristics on at least one said layer (4) of said substance (5) include a press cylinder (110) power-operated cooperating with a embossed belt identifying said embossed surface.

19. Plant according to claim 18, characterised in that said means able to print the desired superficial characteristics to at least one said layer (4) of said substance (5) include moreover heating means able to heat up said substance(δ) and/or said leather (3) or said element to be finished (3) and/or said embossed surface (6) for transforming at least one said layer (4) into a film (F).

20. Plant according to claim 18, characterised in that said embossed belt (212) is closed.

21. Plant according to claim 19 characterised by having moreover an unroller group (320) of said cooperating belt with a roller group (321) of said belt.

22. Plant according to any of claims from 11 to 21 , characterised in that said substance (5) includes a polyurethane resin.

23. Plant according to any of claims from 11 to 22, characterised by having moreover at least one drying oven (322) interposed between said application means and said means able to imprint the desired superficial characteristics to at least one said layer (4) of said substance (5).

24. Plant according to any of claims from 11 to 23, characterised by having also a unit for the detection of the geometric form of said surface (2) of said leather (3) or said sheet-coated material to be finished (3) suitable to control the activation/deactivation of said application means.

25. Finished leather or sheet-coated material characterised by being realized according to the method of any previous claims from 1) to 10).

26. Method and plant substantially according to what has been described also referring to enclosed drawings.