Method for processing raw hide and fabric

Abstract

A method of processing a raw hide, a fabric or the like, comprising the steps of:-wetting the raw hide, covering the raw hide with a predetermined amount of cold water; soaking the raw hide, treating the raw hide with one or more soaking agents and degreasing agents; -retanning said hide, treating said hide with one or more retanning agents; neutralizing the hide, treating the hide with one or more neutralizing agents; -dyeing the raw hide, treating the raw hide with one or more colorants; greasing the raw hide, treating the raw hide with one or more greasing agents; the steps of wetting, soaking, retanning, neutralizing, dyeing and fat liquoring of the raw hide are carried out in a controlled atmosphere environment which is insulated from the surrounding environment; a predetermined temperature and / or humidity condition is generated and maintained in a controlled atmosphere environment.

Description

Technical Field

[0001] The present invention relates to a method for processing hides, textiles and the like. Background Art

[0002] As we all know, animal hides are transformed into leather by tanning, an operation that renders the fibers indecomposable.

[0003] The tanning process is quite lengthy and is carried out in several steps, which generally include the preparation of the hides and the actual tanning.

[0004] The preparatory operation for tanning is basically to remove from the hide all the matter, hair, epidermis, fat layer, etc., that will not be converted into leather.

[0005] These preparatory operations constitute the so-called tanning preparation operations and basically include: soaking, unhairing, liming, scraping, splitting, deliming, bating and degreasing.

[0006] However, after the pre-tanning operations, the hides are still susceptible to decay and the actual tanning must therefore be carried out.

[0007] During the tanning process, the fibers of the hide are impregnated with chemicals that become irreversibly fixed to the hide and transform the perishable hide into a non-perishable material, leather.

[0008] However, the tanned hide cannot yet be used to produce articles, since it consists of wet material and, even when dried, it produces a product of a rather hard, cardboard-like consistency, with the typical tanning color thus obtained: this is the so-called "wet white" or "wet blue" hide.

[0009] Therefore, in order to transform the tanned hides into a saleable product that can be used in the production of articles, they must be subjected to additional chemical and mechanical treatments to impart certain properties to the hides.

[0010] These treatments are usually called "retanning" and basically include: actual retanning, neutralization, dyeing and fatliquoring.

[0011] Before being subjected to these further processing steps, the hides are shaved, ie brought to a uniform thickness, and weighed in order to calculate the amount of water and chemical products to be used.

[0012] The retanning operation is usually carried out using a machine called a drum, which basically consists of a large sealed container that promotes the penetration of chemical products into the hides through its rotational motion.

[0013] The hides are dragged upwards during rotation inside the drum, on specially designed pegs or racks, and then allowed to fall so that they can be immersed in a mixture of water and chemical products contained in the drum.

[0014] The above-mentioned retanning step requires large amounts of water and chemical products, liquids and powders, which must be compulsorily treated in a purification plant, usually with additional chemical products and more water to ensure quality in compliance with current regulations.

[0015] In this respect, a retanning cycle of conventional type requires on average a water quantity in the range of 1000% to 2000% of the weight of the shaved hide.

[0016] The percentage values ​​associated with drainage also generally lie between 1000% and 2000% of the shaved hide weight, all drainage having to be diverted to purging.

[0017] As regards the chemical products used, the amount used is greater than 20% by weight of the shaved hide.

[0018] Furthermore, it should be noted that at the end of the various steps, the hides are wet and require drying processing, resulting in high energy consumption and atmospheric emissions.

[0019] CN110938717A discloses a method for producing white anti-yellowing cow split leather, wherein the wet blue leather is sequentially subjected to rewetting, primary retanning, alkali extraction, secondary retanning, primary dyeing, primary fatliquoring, secondary dyeing, board glueing, drying, softening, polishing and drum grinding.

[0020] CN107938392A discloses a leather retanning and dyeing processing method for reducing the residual dye in dyeing wastewater, wherein a dyeing auxiliary is combined with collagen modified by amino resin for one-bath dyeing. The dye can be relatively completely absorbed by the leather fiber, thereby reducing the residual dye molecules in the wastewater and reducing the difficulty of post-treatment of the dye wastewater.

[0021] US2017 / 233833A1 discloses a method for producing leather from raw animal hides using waste liquid. The process includes the steps of pre-soaking, soaking, dehairing and liming, re-liming, deliming and softening, pickling and tanning, degreasing, retanning, neutralizing, dyeing and fatliquoring, and washing the processed leather. The collected waste liquid can be recycled to the same step, different steps, or two or more steps in the process. Summary of the invention

[0022] The object of the present invention is to provide a method for processing hides, fabrics and the like which overcomes the disadvantages of the cited prior art.

[0023] Within the scope of this aim, a particular object of the invention is to provide a method for making hide processing operations more sustainable by reducing the use of water, chemical products and energy.

[0024] Another object of the present invention is to provide a process which, contrary to traditional processing, allows the so-called "wet" hide processing step to be carried out without the use of any bath.

[0025] Another object of the present invention is to provide a method which can significantly reduce the amount of wastewater to be purified.

[0026] Another object of the present invention is to provide a method for substantially reducing emissions.

[0027] Another object of the present invention is to provide an efficient process which substantially reduces the cost of the final product.

[0028] This aim and these objects, as well as others that will become more apparent hereinafter, are achieved by a method for processing leather and textiles as claimed in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further features and advantages will become more apparent from the description of a preferred but non-exclusive embodiment of a method for processing leather, fabric or the like, shown by way of non-limiting example in the accompanying drawings, in which:

[0030] Figure 1 is a block diagram illustrating the steps of a method according to the present invention. DETAILED DESCRIPTION

[0031] With reference to the cited figures, a method for processing leather, fabrics or the like according to the invention, indicated generally by reference numeral 1 , has considerable flexibility of use; however, it is particularly suitable for processing shaved and preferably tanned hides 2 .

[0032] Before starting the process, the hide 2 is weighed, the main purpose being to determine the amount of water and the various chemical agents used when carrying out the various processing steps.

[0033] The ratios between the weight of the hide 2, the amount of water and the amount of chemical agent can be varied according to various aspects; these amounts are kept within particularly low values ​​relative to the prior art, as better defined below.

[0034] Method 1 comprises a step 3 of wetting the hide 2. The hide is sprayed with cold water. Wetting step 3 is followed by a soaking step 4, during which the hide 2 is treated with a soaking agent and a degreasing agent. The method comprises a further retanning step 5 for retanning the hide 2 treated with the retanning agent.

[0035] In the present context, the term "cold water" generally refers to water that is not heated.

[0036] The soaking step 4 and the retanning step 5 respectively have the purpose of cleaning the hide 2 of coarser dirt and improving its aesthetics by filling its voids, thereby giving the hide the desired fullness and firmness.

[0037] The hide 2 is then subjected to a neutralization step 6, during which the hide 2 is treated with a neutralizing agent to bring the pH value of the hide 2 to an optimum value for subsequent penetration and fixation with chemical agents.

[0038] The neutralization step 6 is followed by a dyeing step 7 during which a dye is applied to the hide 2 .

[0039] The hide 2 is then subjected to a fatliquor step 8, in which the hide 2 is treated with a fatliquor which substantially "lubricates" the inner fiber structure of the hide, giving it particular organoleptic properties.

[0040] The steps of method 1 preferably occur in the order described above.

[0041] However, it is important to note that the above steps may also be performed sequentially in a different order, or in actual operation, some steps indicated as separate steps may be combined together without thereby abandoning the scope of the present invention.

[0042] According to the invention, at least the above steps of wetting 3, soaking 4, retanning 5, neutralizing 6, dyeing 7 and fatliquoring 8 of the hides 2 are carried out in a controlled atmosphere environment 20 thermally insulated from the surrounding environment.

[0043] In more detail, the controlled atmosphere environment 20 is generally an environment within which predetermined temperature and / or humidity conditions can be created and maintained.

[0044] Advantageously, such a controlled atmosphere environment 20 is formed, for example, by a climate-controlled chamber, substantially sealed and thermally insulated from the external environment, into which the hides 2 are introduced in order to carry out the various processing steps described.

[0045] The chamber preferably comprises a perforated inner wall and an insulating outer wall which is sealed except for an opening for loading / unloading the hides 2 .

[0046] The method is advantageously implemented by using a machine, not shown in the attached drawings, comprising a structure supporting a substantially cylindrical insulated barrel which, in actual operation, forms a controlled atmosphere environment 20. A perforated basket containing the hides 2 is rotatably mounted inside the barrel and rotated by an electric motor. The barrel and the basket are respectively provided with loading / unloading aligned openings with doors. Preferably, the machine is equipped with an air handling unit which, also with the help of dedicated software, allows to create and maintain the optimal temperature and / or humidity conditions for carrying out the method inside the barrel.

[0047] According to the method of the invention, water, soaking and degreasing agents, retanning agents, neutralizing agents, dyes and fatliquor are quantitatively applied in a controlled atmosphere environment 20 with the aid of suitable devices capable of spraying / atomizing these products, so that these products are diffused in the form of droplets, i.e. in the form of aerosols, so as to allow and promote a uniform and cohesive absorption of these agents by the rawhide 2.

[0048] Contrary to the conventional prior art methods, the present invention allows avoiding the immersion of the hides 2 in a treatment bath, thereby significantly reducing the use of water and chemical products compared to the prior art.

[0049] According to the method of the invention, a quantity of cold water less than or equal to 100% of the weight of the hide 2 and a quantity of chemical product less than or equal to 20% of the weight of the same hide 2 are used.

[0050] According to another aspect of the invention, the fatliquoring step 8 is followed by a pre-drying step 9, during which the residual moisture of the hide 2 is reduced to a target percentage.

[0051] In this regard, experimental tests carried out by the applicant and a careful analysis of the results have shown that, after the pre-drying step 9, the moisture content of the hide 2 can be lower than 20% of its initial weight.

[0052] Advantageously, the pre-drying step 9 is performed by controlling the temperature and / or humidity of the controlled atmosphere environment 20, wherein "control" refers to the ability to measure and adjust the temperature and / or humidity in this environment by acting on the corresponding parameters.

[0053] The hide 2 is then extracted from the controlled atmosphere environment 20 and laid out on beams for a final drying step 10 .

[0054] According to another aspect of the invention, in step 11, at least some of the vapor generated within the controlled atmosphere environment 20 during performance of method 1 is condensed and recovered in the form of a liquid.

[0055] This liquid is collected together with the liquid originally used to soak the hides 2 and purified, for example by filtration and decanting, in such a way that it can be at least partially recycled in the same process 1 or in a subsequent process.

[0056] In particular, the recovered liquor can be used, for example, to dilute the chemical products used in method 1 or to soak other hides for subsequent treatment.

[0057] In this way, only a very small amount of the aqueous solution used during method 1 is treated in the civil sewage treatment plant 12.

[0058] In practice, the present invention has been found to achieve its intended aim and objects and to provide a method of processing hides, fabrics and the like which makes the leather processing operation commonly known as retanning significantly more sustainable.

[0059] In fact, as shown in the figure, the method according to the invention makes it possible to reduce the use of water, chemical products and energy.

[0060] In particular, by using water and chemical products sprayed / atomized in the form of droplets, ie in the form of an aerosol, the method according to the invention achieves the important advantage of avoiding the use of a treatment bath to perform the wetting step of hide processing.

[0061] Furthermore, the process according to the invention allows a significant reduction in the wastewater to be purified and in the atmospheric emissions produced thereby.

[0062] Furthermore, all chemical products used in the method according to the invention are natural and chemically related to leather.

[0063] The method according to the invention saves a lot of money in economic terms and at the same time protects the environment and the health of the workers.

[0064] This application claims the benefit of Italian Patent Application No. 102022000012671 filed on June 15, 2022, the subject matter of which is incorporated herein by reference.

Claims

1. A method for processing hides and fabrics, comprising the following steps: - wetting the hide by covering it with a predetermined amount of cold water; - soaking the hides and skins, treating the hides and skins with one or more soaking agents and degreasing agents; - retanning the hide, treating the hide with one or more retanning agents; - neutralizing the hide, treating the hide with one or more neutralizing agents; - dyeing the hide, treating the hide with one or more dyes; - fatliquoring of hides and skins, treating the hides and skins with one or more fatliquor agents; The method is characterized in that the steps of wetting, soaking, retanning, neutralizing, dyeing and fatliquoring of the rawhide are carried out in a controlled atmosphere environment which is thermally insulated from the surrounding environment; and predetermined temperature and / or humidity conditions are generated and maintained in the controlled atmosphere environment.

2. The method according to claim 1, characterized in that The method comprises the step of pre-drying the hide, controlling at least the temperature and / or the humidity of the controlled atmosphere environment.

3. The method according to one or more of the preceding claims, characterized in that The water, the soaking and degreasing agents, the retanning agent, the neutralizing agent, the dyeing agent and the fatliquor are quantitatively added into the controlled atmosphere environment by means of a spraying / atomizing device, which is suitable for diffusing the water and the agents in the form of droplets or aerosols, allowing and promoting their uniform and cohesive absorption by the rawhide.

4. The method according to one or more of the preceding claims, characterized in that The amount of water used to wet the hide is less than or equal to 100% of the weight of the shaved hide.

5. Method according to one or more of the preceding claims, characterized in that The amount of said soaking and degreasing agent, said retanning agent, said dyeing agent, said fatliquor and said neutralizing agent used for treating said hides is lower than or equal to 20% of the weight of the shaved hides.

6. Method according to one or more of the preceding claims, characterized in that During the process, at least a portion of the vapor generated in the controlled atmosphere environment is condensed and recovered in liquid form.

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

8. Method according to one or more of the preceding claims, characterized in that The controlled atmosphere environment is formed in a climate-controlled chamber, which is substantially sealed and insulated from the external environment, and the rawhide is fed into the climate-controlled chamber to perform the processing provided by the method; the chamber includes a perforated inner wall and an outer insulating wall, which is airtightly closed except for an opening for loading / unloading the rawhide.

9. Method according to one or more of the preceding claims, characterized in that The chamber is arranged in a generally cylindrical insulated barrel supported by a supporting structure; a perforated basket for the rawhide is rotatably mounted in the barrel; the basket is rotatable around a corresponding axis with the aid of a motor device; the barrel and the basket are provided with respective loading / unloading openings, which are generally aligned with each other; there is an adapted door at the loading / unloading opening; and an air handling unit is suitable for generating and maintaining predetermined temperature and / or humidity conditions in the barrel.

10. Method according to one or more of the preceding claims, characterized in that The pre-dried hides are removed from the controlled atmosphere environment and laid out on beams for final drying.

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