Process of treating skins and hides

Abstract

A process of treating skins and hides includes the steps of: washing the hide to be treated with water; deliming the hide with suitable deliming agents to remove residual lime; bating the hide with suitable bating agents to eliminate keratin degradation products, hair and epidermis residues; re-washing the hide with water; pickling the hide with suitable pickling agents to lower the pH; tanning the hide with suitable tanning agents to prevent attacks by microorganisms; cross-linking the hide with suitable crosslinking agents to permanently fix the tanning agents to the hide; the phases of washing, deliming, bating, re-washing, pickling, tanning and cross-linking the hide are carried out in a treatment chamber that is thermally insulated from the outside, wherein the temperature, humidity, and quantity of water are constantly monitored.

Description

[0001] PROCESS OF TREATING SKINS AND HIDES

[0002] The present invention relates to a process of treating skins and hides of animals.

[0003] As is well known, animal hides are processed into leather by tanning, making it more durable and less susceptible to decomposition.

[0004] The tanning process is quite lengthy and consists of several steps, including tanning preparation operations and the actual tanning.

[0005] The tanning preparation operations essentially serve to rid the hides of components (hair, epidermis, fatty layer, dirt, etc.) that will not be transformed into leather.

[0006] In particular, those preparatory operations include greening, depilation and liming, and possibly fleshing and splitting.

[0007] Greening is the first preparatory operation and its main purpose is to clean the hide and give it back the water lost after slaughter, during storage.

[0008] Depilation and liming are chemical operations that respectively serve to remove hair, epidermis and part of the fatty layer, and to loosen the fibrous entanglement of the hide by favoring the absorption of tanning agents.

[0009] Fleshing is a mechanical operation, performed by a bladed cylinder, for removing meat residues and the fatty tissue of the subcutaneous layer, known as skivings.

[0010] Splitting is a mechanical operation that separates the hide into two parts: a more valuable layer, the 'grain', and a less valuable layer, the flesh split.

[0011] After the preparatory operations the hide is still putrescible and easily subjected to bacterial attack and has to undergo the actual tanning process.

[0012] During tanning, the hide fibers are impregnated with chemicals that irreversibly attach to the fibers and transform the putrescible hide into a stable, rot-resistant material, i.e. leather.

[0013] The tanning operations are generally carried out using machines, known as drums, essentially consisting of large, watertight rotating containers that allow the penetration of the chemicals into the hide.

[0014] Inside the drum, special pegs, or paddles, drag the hide to be treated upwards as it rotates, and then drop the hide so that it can soak in the mixture of water and chemicals contained in the drum.

[0015] The tanning steps described above require considerable quantities of water and chemicals, liquids and powders, that must then be compulsorily disposed of in a purification plant, often resorting to additional chemicals and water to ensure a quality that complies with current regulations.

[0016] In this regard, a traditional tanning cycle requires on average 400% to 600% of water by weight, compared to the weight of the animal hides and hides freed from the hair and flesh.

[0017] The percentage values for water discharge are also substantially between 400% and 600% by weight, compared to the weight of pelts, and all discharged water must be subjected to purification.

[0018] As for the chemicals used, they are generally used in quantities of between 18% and 25% by weight, relative to the weight of the pelts.

[0019] Therefore, conventional tanning methods pose severe problems from environmental, toxicological and energy points of view.

[0020] The aim of the present invention is to provide a process for treating hides that overcomes the drawbacks of the prior art.

[0021] Within the scope of this aim, a particular object of the invention is to provide a process that makes the hide processing operations more sustainable by decreasing the use of water, chemicals and energy.

[0022] A further object of the invention is to provide a process that allows the tanning treatment of hides without having to immerse the hides to be treated in a bath, as is the case with conventional processes.

[0023] A further object of the invention is to provide a process that allows a considerable reduction in the amount of water to be purified.

[0024] A further object of the invention is to provide a process that substantially reduces atmospheric emissions.

[0025] A further object of the invention is to provide a highly efficient process that minimizes the costs of the final product.

[0026] This aim and these objects, as well as others that will become better apparent hereinafter, are achieved by a process of treating skins and hides as claimed in the appended claims.

[0027] Further features and advantages will become better apparent from the description of a preferred but not exclusive embodiment of the invention, illustrated by way of non-limiting example in the flowchart of figure 1 .

[0028] The process for treating hides according to the invention, generally designated by the reference numeral 1 , has considerable flexibility of use and the herewith described embodiment is particularly suitable for processing hides or pelts 2, namely hides freed from hair and flesh, that are first weighed as received from the supplier.

[0029] Knowing the exact weight of the hide 2 to be treated allow to determine the quantity of water and chemical agents to be used during the various steps of the process 1.

[0030] The proportions between the weight of hide 2 to be treated, the amount of water, and the amount of chemical agents may vary depending on various aspects, and are generally kept within particularly low values, compared to the conventional prior art processes, as will be better apparent in the following description.

[0031] The process 1 comprises an initial washing step 3 wherein the hide 2 to be treated is sprayed with water in quantities of up to 100% by weight, with reference to the weight of the hide, in order to remove any impurities and residues present.

[0032] The washing step 3 is followed by a deliming step 4, wherein, by means of suitable deliming agents, the hide 2 is freed from the products used during deliming.

[0033] A bating step 5 follows the deliming step 4 wherein the hide 2 is processed with suitable bating agents to eliminate keratin degradation products, hair and epidermis residues.

[0034] The process 1 continues with a re-washing step 6 whereby the hide 2 is sprayed with water in quantities up to 100% by weight, with reference to the weight of the hide.

[0035] In a following pickling step 7, the hide 2 is treated with pickling agents, i.e. acidifying agents, that bring the hide 2 to an optimal pH value for the penetration and fixation in the dermis fibers of the tanning agents used subsequently.

[0036] At this point, the hide 2 is ready to undergo a tanning step 8, wherein tanning agents are irreversibly fixed to the hide proteins, blocking any possibility of attack by microorganisms.

[0037] The tanning step 8 is followed by a cross-linking step 9, wherein the tanning agents are permanently fixed on the hide 2 by means of cross-linking agents.

[0038] The above-described sequence of steps may be altered and some of such steps may be merged without departing from the scope of the invention.

[0039] According to a preferred embodiment of the invention, at least the steps of washing 3, deliming 4, bating 5, re-washing 6, pickling 7, tanning 8 and cross-linking 9 are carried out inside a treatment chamber 20 which is thermally insulated with respect to the outside, and wherein the temperature, humidity and quantity of water present inside the chamber are constantly controlled.

[0040] By “controlled” it is meant that the temperature and / or humidity and / or water quantity are constantly measured and regulated inside the treatment chamber 20 by acting on the relevant parameters.

[0041] According to an embodiment of the invention, the treatment chamber 20 is constituted by an insulated casing containing a partially perforated wall, configured to delimit an area intended to receive the hide 2.

[0042] The insulated casing also contains suitable means for controlling temperature, humidity and the amount of water.

[0043] According to this embodiment of the invention, the insulating casing has a loading / unloading opening, selectively sealable by means of a lid, while the perforated wall has openings configured to allow the passage of air and liquids.

[0044] According to an embodiment of the invention, the process 1 is actuated by a machine, not illustrated in the drawings, having a supporting structure that supports a substantially cylindrical insulated tank that forms the treatment chamber 20.

[0045] A basket, at least partially perforated, is coaxially and pivotally mounted inside the tank; the basket is designed to hold the hides 2 to be treated and can be rotated by means of an electric motor.

[0046] The tank and the basket have respective loading / unloading openings having special doors that can be sealing closed in a selective manner. The machine has an air-handling unit serviced by hardware and software means and configured to generate and maintain optimal temperature and / or humidity and / or water quantity conditions for the execution of the process 1 .

[0047] Advantageously, water, deliming agents, bating agents, pickling agents, tanning agents and crosslinking agents are dosed inside the treatment chamber 20 in the form of droplets or aerosols, in order to allow and promote their uniform and cohesive absorption by the hide 2.

[0048] The process according to the invention therefore makes it possible to avoid immersing the hide 2 in treatment baths, contrary to conventional methods, thus considerably reducing the use of water and chemicals compared to the prior art systems.

[0049] In particular, the system according to the present invention allows a reduction of an amount of water up to 200% by weight, with reference to the weight of the pelts, and an amount of chemicals reduced to approximately 30% by weight, with reference to the weight of the pelts, compared to the prior art.

[0050] According to a further aspect of the invention, the cross-linking step 9 is followed by a pre-drying phase 10, wherein the amount of residual humidity in the hide 2 is reduced to a target percentage.

[0051] Advantageously, the pre-drying step 10 is also implemented by controlling the temperature and / or humidity and / or amount of water inside the treatment chamber 20.

[0052] The hide 2 is then extracted from the treatment chamber 20, laid out on pallets and pressed in a pressing step 11 , before undergoing subsequent mechanical actions such as splitting and shaving.

[0053] According to further aspect of the invention, at least part of the vapors that develop inside the treatment chamber 20 are condensed and recovered in liquid form in a liquids recovering step 12.

[0054] The recovered liquid, together with the liquid used to wash and re-wash the hide 2, is collected and purified, e.g. by filtration and decantation, so that it can be at least partly recycled within the same process 1 or in a subsequent process.

[0055] In particular, the recovered liquid can be used, for example, to dilute the chemicals used in the process 1 , or to wash other hides for further treatment. In this manner, only a fraction of the water of the aqueous solution used during the process is disposed of according to a conventional waste water treatment cycle 13.

[0056] In practice, it has been found that the invention achieves its intended aim and objects, providing a process for treating hides that makes the hides processing operations, i.e. tanning, decidedly more sustainable.

[0057] In fact, the process according to the invention makes it possible to substantially reduce the use of water, chemicals and energy used.

[0058] In particular, by using water and chemicals in droplet or aerosol form in the process according to the invention, it is possible to achieve the important advantage of avoiding the use of treatment baths to tan the hides.

[0059] The process according to the invention also makes it possible to considerably reduce the water discharge to be purified, as well as to substantially reduce the resulting emissions into the atmosphere.

[0060] Moreover, all chemicals used in the process according to the invention are natural and chemically related to hides.

[0061] This not only results in considerable savings in economic terms, but also protects the environment and the health of the workers.

[0062] This application claims the priority of Italian Patent Application No. 102023000026547, filed on December 13, 2023, the subject matter of which is incorporated herein by reference.

Claims

CLAIMS1 . A process of treating hides, comprising the steps of:- washing (3) a hide (2) to be treated with water;- deliming (4) said hide (2) with deliming agents to remove residual lime;- bating (5) said hide (2) with bating agents to eliminate keratin degradation products, hair and epidermis residues;- re-washing (6) said hide (2) with water;- pickling (7) said hide (2) with pickling agents to lower the pH;- tanning (8) said hide (2) with tanning agents to prevent attacks by microorganisms;- cross-linking (9) said hide (2) with cross-linking agents to permanently fix said tanning agents to said hide (2); said process being characterized in that said steps of washing (3), deliming (4), bating (5), re-washing (6), pickling (7), tanning (8), and cross-linking (9) are carried out in a treatment chamber (20) thermally insulated from the outside, wherein temperature, humidity and quantity of water inside said chamber are constantly monitored.

2. The process, according to claim 1 , characterized in that it comprises an additional step of pre-drying (10) said hide (2); said step of pre-drying (10) said hide (2) being carried out in said treatment chamber (20) after the step of cross-linking (9) said hide to be treated (2).

3. The process, according to one or more of the preceding claims, characterized in that the pre-dried hide is taken out of the treatment chamber (20) and is spread on pallets for subsequent operations.

4. The process, according to one or more of the preceding claims, characterized in that said water, said deliming agents, said bating agents, said pickling agents, said tanning agents, and said cross-linking agents are dosed in said treatment chamber (20) in the form of droplets or aerosols, allowing and promoting their uniform and cohesive absorption by said hide (2).

5. The process, according to one or more of the preceding claims, characterized in that the quantity of water used for washing and re-washing said hide (2) is less than orequal to 200% by weight, with reference to the weight of the hide.

6. The process, according to one or more of the preceding claims, characterized in that the quantity of said deliming agents, said bating agents, said pickling agents, said tanning agents and said cross-linking agents used for treating said hide (2) is reduced to about 30% by weight, with reference to the weight of the hide.

7. The process, according to one or more of the preceding claims, characterized in that at least part of the vapors developing in said treatment chamber (20) during said process is condensed and recovered (12) in the form of liquid.

8. The process, according to one or more of the preceding claims, characterized in that said liquid is collected and purified in such a way that it can be at least partially reused in said process or in a subsequent process.

9. The process, according to one or more of the preceding claims, characterized in that said treatment chamber (20) is formed by an insulating casing comprising an at least partially perforated wall placed inside it; said at least partially perforated wall delimiting at least one area adapted to receive said hide (2); said casing being operatively connected to means for controlling temperature, humidity and quantity of water present within said treatment chamber (20).

10. The process, according to one or more of the preceding claims, characterized in that said casing has at least one loading / unloading opening and a door movable between a closed position, wherein said door seals said loading / unloading opening, and an open position, wherein said door does not interfere with said loading / unloading opening.11 . The process, according to one or more of the preceding claims, characterized in that said at least partially perforated wall comprises a plurality of openings configured to allow the passage of air and liquids.

12. The process according to one or more of the preceding claims, characterized in that said means for controlling temperature, humidity and quantity of water present within said treatment chamber (20) include hardware and software means configured to generate and maintain optimal temperature and / or humidity and / or quantity of water conditions within said casing.

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