Classifications

• • C—CHEMISTRY; METALLURGY
  • C14—SKINS; HIDES; PELTS; LEATHER
  • C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
  • C14C15/00—Apparatus for chemical treatment or washing of hides, skins, or leather
• • C—CHEMISTRY; METALLURGY
  • C14—SKINS; HIDES; PELTS; LEATHER
  • C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
  • C14C1/00—Chemical treatment prior to tanning
• • C—CHEMISTRY; METALLURGY
  • C14—SKINS; HIDES; PELTS; LEATHER
  • C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
  • C14C3/00—Tanning; Compositions for tanning

Definitions

• the present invention concerns tannage of leather and the like
• This treatment includes different steps, which are often complex and requiring relatively much time
• rawhide When delivered to tannery, generally dried with salts, rawhide is initially subjected to preparation for real tanning
• This preparation includes first a soaking step, i e removing impurities that cover both inner flesh side and outer or gram side, as well as preserving solutions, so as to bring the leather back to its natuFal softness
• the leather to be treated is soaked in drums containing suitable liquid solutions
• drums are provided inside with immovable paddles or stakes, which act on the leather during drum rotation Therefore, the treatment consists of combined chemical action of the liquid solution and the mechanical action performed on the leather and lasts six to twenty four hours
• a fleshing step follows, with which the fat is removed from the soaked leather, and subsequently liming treatment follows for removing hair and reveal the derma
• Liming is performed in suitable drums with alkaline substances, such as sulphides or lime, which make the leather tissue swell and dissolve the hair roots
• the leather swells up, the fats turn into calcium salts and proteins forming the leather are modified due to breaking of principal and secondary links of the proteic chains and, subsequently, the hair detaches from the leather
• Bating is a biological action which softens leather grain by enzymes which partly dissolve elastic fibres, causing the leather relaxation
• the leather is subjected to pickling, i.e treatment, which guarantees more rapid and complete penetration of the tanning salts.
• bated leather having basic reaction, cannot be tanned with e.g. tanning salts of chromium, because it would result in a chemical reaction, which would close the leather pores.
• the leather is acidified with small quantities of acid, with the presence of salts (usually sodium chloride) so as to prevent swelling
• salts usually sodium chloride
• the real tanning treatment is carried out inside the aforementioned drums, by means of vegetable solutions, such as natural or synthetic tanning solutions, or by mineral salts, mainly chromium or the like salts.
• vegetable solutions such as natural or synthetic tanning solutions
• mineral salts mainly chromium or the like salts.
• the liming, bating, pickling and tanning steps altogether require an average of not less than forty eight hours (it can vary according to the type of the leather to be treated).
• the tanned leather suitably pressed to remove a part of absorbed water, selected and skived, is subjected to dyeing treatment, otherwise called re- tanning.
• This dyeing step requires an average of eight hours
• tanning treatments require, as has been already said, much time, which can take an average of one week.
• a not minor disadvantage of traditional tanning processes derives from the fact that the working environment is very harmful, due mainly to miasma produced by the aforementioned drums.
• the object of the present invention is to propose a process, that allows tanning treatments of leather and the like to be carried out in less time with respect to the known systems, and that, at the same time, guarantees the high quality of tanned leather as well as high throughput, the whole being obtained with reduced quantity of required energy, with respect to known techniques.
• Another principal object of the present invention is to propose a process that can be carried out by an apparatus, which allows to operate in a non-harmful working environment, and which considerably reduces the problems connected with waste disposal.
• the invention has another object of proposing an apparatus, which carries out the aforementioned method.
• a process of treatment of leather and the like which includes: disposing spread pieces of leather to be treated, spaced apart, into a container; introducing liquid solutions into said container, in sequence and with predetermined intervals, for performing various steps of leather tanning treatment, said liquid solutions being discharged from the container, after each step has been completed; maintaining depression inside said container, at least for the duration of each single step; generating, during each step, a relative movement between the liquid solution and said pieces of leather, so as to intensify the action of said liquid solution on said pieces of leather
• the process is carried out by means of an apparatus which includes a container to be closed tight, a plurality of supports, which can be introduced and withdrawn from said container, and on which the corresponding spread pieces of leather are fastened, these supports being situated in said container in such a way as to keep said pieces of leather spaced out, a first series of tanks containing predetermined liquid solutions for corresponding leather treatment steps, on/off and control means which connect each of said tanks to the container so as to introduce therein the relative liquid solution for corresponding leather treatment step, suction means for maintaining depression inside said container at least while performing the leather treatment steps, means for generating relative movement between a liquid solution and said pieces of leather so as to intensify the action of said liquid solution thereon
• the process includes disposing spread pieces of leather to be treated, spaced apart, into a first container, introducing liquid solution into said container for performing a step of leather tanning treatment, maintaining depression inside said container during performing of said step, generating, during said step, relative movement between the liquid solution and said pieces of leather, so as to strengthen the action of said liquid solution on said pieces of leather, discharging said liquid solution from said first container, withdrawing said pieces of leather from the first container, repeating the above mentioned operations in further containers so as to perform remaining steps of the leather tanning treatment
• the apparatus includes a plurality of containers to be closed tight, inside which predetermined leather treatment steps are carried out, a plurality of supports, which can be introduced and withdrawn from said containers, and on which the corresponding spread pieces of leather are fastened, these supports being situated in said containers in such a way as to keep spaced out said pieces of leather; a first series of tanks containing predetermined liquid solutions for corresponding leather treatment steps; on/off and control means, which connect each of said tanks to the relative container so as to introduce therein the relative liquid solution for a corresponding leather treatment step; suction means for maintaining depression inside each of said containers at least during performing therein of the relative leather treatment steps; means for generating, inside each of said containers, relative movement between a corresponding liquid solution and said pieces of leather so as to intensify the action of said liquid solution thereon. Further characteristics and features are pointed out in the sub-claims.
• - fig. 1 shows a plan view of supporting means for a piece of leather to be treated
• FIG. 2a, 2b and 2c show schematic views of containers into which the above mentioned support means are disposed, with different arrangements, respectively;
• - fig. 3 shows a schematic vertical section view of said container, during one step of the leather treatment
• FIG. 4a and 4b show diagrams of apparatuses for carrying out corresponding tanning treatments according to the method, being the subject of the present invention
• FIG. 5a, 5b show diagrams of two different embodiments of the above mentioned apparatus, which carry the method in a different way;
• - fig. 6 shows a possible diagram of an apparatus, which carries the method in a further way;
• - Fig. 7 shows a further embodiment of the apparatus;
• FIG. 9a and 9b show two schematic diagrams of a facility for vapour recovey in both operation conditions.
• numeral 1 indicates a piece of leather to be subjected to tanning treatment according to the subject process.
• the piece of leather to be treated 1 is spread on a respective open support, e.g. frame 2 shown in fig. 1.
• the piece of leather 1 is fastened to the frame 2 by a series of expanders 3 of known type.
• the frames 2 supporting the spread pieces of leather 1 are introduced into a container 4, kept fixed according to preferred embodiment, which is to be closed tight, for the treatment with a suitable liquid solution introduced therein.
• the frames 2 supporting the spread pieces of leather 1 are introduced into the container 4 preferably in vertical arrangement, regularly spaced apart, as seen in figure 2a.
• the upper part of the container 4, which contains the treating liquid solution 5, is closed tight by a cover 6.
• the container 4 In its lower part, the container 4 has holder means 7 for the frames 2 supporting the pieces of leather 1.
• a heat exchanger 8 that heats the liquid solution 5 to the desired temperature.
• the liquid solution 5 inside the container 4 is swirled during the treatment of the leather pieces 1 spread on the frames 2.
• the container 4 features a deliver element 9, situated below the holder means 7 for the frames 2 and formed by a grate provided with a series of ejectors 10, which eject air in form of bubbles.
• a flow of air is sucked from outside via the deliver element 9. Further, the depression reduces the quantity of energy consumed for reaching the desired working temperature. Otherwise, the aforementioned flow of air can be obtained by suitable compression means, connected to the deliver element 9.
• the apparatus for tanning treatments shown in fig. 4a, includes a series of tanks 12, preferably tight, containing liquid solutions to be supplied to the container 4 for the aforementioned treatments.
• tanks 12a, 12b, 12c, 12d supplying liquid solutions used correspondingly for the soaking, liming, pickling and tanning steps.
• the tanks are provided with respective heat exchangers 13a, 13b, 13c, 13d which maintain the liquid solutions at desired temperatures.
• the heat exchangers 13a, 13b, 13c, 13d are controlled by a control unit 14 by connections indicated with S1 , S2, S3 and S4.
• the supply tanks are connected with respective jet pipes 15a, 15b, 15c and 15d, equipped with related pumps 16a, 16b, 16c and 16d, controlled, in their turn, by the control unit 14 through connections indicated with P1 , P2, P3 and P4.
• the jet pipes 15a, 15b, 15c and 15d are connected to an inlet pipe 17 of the container 4 by a valve means 18 which is controlled by the control unit 14.
• the bottom of the container 4 features an outlet pipe 19, provided with a pump 20, controlled by the control unit 14.
• the outlet pipe 19 is connected alternatively, by a valve means 21, with discharge pipes 22a, 22b, 22c and 22d, communicating with respective waste tanks 23a, 23b, 23c and 23d of the liquid solutions used in the container 4.
• the waste tanks 23 communicate with corresponding supply tanks 12 by means of respective return pipes 24a, 24b, 24c, 24d, equipped with respective pumps 25a, 25b, 25c, 25d, controlled by the control unit 14.
• the discharge pipes 22a, 22b, 22c and 22d lead all to a unique manifold (which has not been shown) which is connected to a suitable cleaner.
• the container 4 is fed with the liquid solution taken from the relative supply tank 12.
• the apparatus includes also at least other two tanks 30a, 30b, containing washing liquid solutions, which will be described later, and provided with relative jet pipes 31 , 31b, featuring relative pumps 32a, 32b controlled by the control unit 14.
• These pipes are connected to an inlet duct 33 of the container 4 by a valve means 34 controlled by the control unit 14.
• the aforementioned outlet pipe 19, connected to the bottom of the container 4, can be also connected, by the valve means 21 , to one or the other of discharge pipes 35a, 35b, flowing into the tanks 30a, 30b, respectively.
• liquid solution is swirled by the air flow produced, as has been previously described, in the liquid solution. It is to be pointed out that before each single step is carried out, more precisely, before the container is fed with liquid solution, depression is created therein so as to swell the leather making it spongy and thus facilitating the action of liquid solution thereon.
• the above mentioned swirling causes a kind of massage on the leather pieces, that replaces the mechanical action of known systems without damaging the leather.
• the used liquid solution is withdrawn from the container 4 and sent to the relative waste tank 23. After having been regenerated, by means of techniques which are well known by those skilled in the art, this liquid solution can be let again into the corresponding supply tank 12, for a new tanning cycle.
• the soaking treatment is carried out with the liquid solution contained in the tank 12a; water, possibly added with chemical promoters.
• the liming treatment is performed with the liquid solution contained in the tank 12b, according to oxidising method, e.g. by sodium chlorite or enzyme agents.
• the combined effect of depression, which swells the leather, of sodium chlorite and of massage performed on the leather by the swirled air, allows to carry out the liming treatment.
• the pieces of leather are not mechanically stressed. It is also to be pointed out that the leather swelling makes also the pores open, which is advantageous for subsequent tanning and dyeing treatments.
• the liming step requires about five hours. After having been limed, the leather is washed with the contents of the tank 30b.
• the liming step is followed by pickling step, which is carried out using the contents of the tank 12c; the effect of this operation is intensified by the massage of the leather performed by the swirling.
• the liquid solution contained in the tank 12d is used for the real tanning step and, when needed, for the dyeing step, the latter being performed by colouring agents (e.g. vegetable colouring agents) dispersed in the liquid solution.
• colouring agents e.g. vegetable colouring agents
• This liquid solution can also contain agents facilitating leather greasing.
• the time required for accomplishment of these steps is reduced because the pores remain open due to the depression effect. Also the quantity of tanning and dyeing substances is lower with respect to traditional methods.
• the concentration in the liquid solution of the tanning and dyeing agents, which are transferred from the liquid solution to the leather (where they remain irreversibly fixed), is reduced with respect to known systems, therefore the quantity of these agents is smaller, but the quality of the obtained result remains the same.
• the pickling, tanning and dyeing operations require about 24 - 36 hours.
• the real tanning treatment can be preceded by the so-called pre-tanning and that dyeing (known also as re-tanning), carried out simultaneously with the agents for leather greasing, can be performed separately from and after the real tanning treatment.
• dyeing known also as re-tanning
• the apparatus that carries out the above mentioned variants, is schematically shown in fig. 4b, where the numeral 12e indicates the tank containing the liquid pre-tanning products, 23e indicates the tank containing the waste liquid after the pre-tanning has been completed, 30d indicates the tank containing the solution for washing the leather after the pre-tanning has been completed, 12f indicates the tank with liquid solution for leather re-tanning and greasing and 23f indicates the tank, which receives waste from the container 4 after the last step has been completed.
• the process being the subject of the present invention, allows to carry out leather tanning in considerably reduced amount of time, with respect to the traditional techniques, guaranteeing at the same time a high quality of the tanned leather.
• the leather pieces are not subject to violent mechanical stresses, but only to a kind of massage produced by said swirling movement, which results in obvious quality advantage.
• An important feature of the subject process derives from the fact that it is carried out in closed tight containers. Thus, the diffusion of miasma into the environment is avoided, improving the working conditions in the field of the leather tanning treatment.
• the proposed process considerably reduces the problem of the waste disposal and/or neutralisation and allows to save both energy and substances used particularly for tanning and dyeing.
• Fig. 5a shows another embodiment of the subject apparatus, in which more treatment containers are used for carrying out a process with the same steps as described for the apparatus of the fig. 4a.
• the frames 2, supporting the spread pieces of leather are mounted, e.g. on a carrier 28, integral with conveying means 29, which introduce and withdraw said carrier 28 into and from the containers 4a, 4b, 4c, 4d.
• These conveying means 29 include e.g. a carriage 30, that is moved, by not shown motor means, along a guide element 31 integral with a fixed frame 32 of the apparatus. Consequently, in each container there is carried out a predetermined step of the leather treatment and a possible washing of said leather.
• the leather is washed in corresponding auxiliary containers 114a, 114b (see fig. 6).
• the leather is withdrawn therefrom and introduced into the auxiliary container 114a, in which it is washed with a liquid solution taken from the tank 30a.
• the liming step is carried out in the container 4b and the subsequent washing in the relative auxiliary container 114b.
• the apparatus shown in fig 5b carries out the treatment steps already described with reference to fig 4b
• the leather is soaked, limed, pickled, pre- tanned, tanned, and lastly, dyed with simultaneous greasing
• washing following the soaking, liming and pre-tanning steps can be carried out in relative auxiliary containers like in the case illustrated in fig 6
• the preferred embodiment of the process features the following technical- functional aspects - container 4 (or containers) kept fixed,
• the container 4 (or containers 4a, 4b, 4c, 4d) can rotate about their transversal and/or longitudinal axis, so as to create a relative movement between the pieces of leather and the liquid solution used in a treatment step or subsequent washing
• the liquid solution contained in the tanks 111a, 111b reduces dramatically and /or neutralises all the volatile compounds, which are generated inside the container 4 (or containers 4a, 4b, 4c, 4d, 4e, 4f) during the leather treatment
• more containers 111 can be provided, arranged parallel one to another, and each of them containing a liquid solution for reducing dramatically and/or neutralising at least one predetermined volatile compound.
• control unit 14 it is possible for the control unit 14 to act on suitable means (e.g. electric valves) connected with these tanks, so as to introduce one or more of them, arranged in a row, into the pipe 110, in relation to the treatment step being carried out in the container 4 and therefore, to the kind of the volatile compound generated during this step.
• suitable means e.g. electric valves
• the pipe 110 connecting each of them to suction means 11 , is linked with a series of tanks 111 performing the above described functions.
• Each supply tank can be provided with means for mixing the liquid solution contained therein, means which are not shown since they are in the knowledge of those skilled in the art.
• Figure 7 shows another embodiment of the apparatus, in which numerals 201, 202, 203, 204 indicate supply tanks containing the liquid solutions for soaking, liming, pickling and tanning.
• numerals 212a, 212b, 212c, 212d indicate corresponding heat exchanger (controlled by the control unit 14 via links S1, S2, S3, S4).
• Numerals 216a, 216b, 216c, 216d indicate the corresponding supply pumps also operated by the control unit 14, via connections P1 , P2, P3 and P4.
• the ejector means, or grating 9 can be set in communication with outside (normal operation condition of the container 4) via a related electric valve 250 operated by the control unit.
• the ejector means 9 can be connected to one or another of a series of auxiliary supply tanks 300a, 300b, 300c, 300d (for instance, four tanks have been provided, however, their number can be bigger or smaller than four), via related electric valves 301a, 301b, 301c, 301d also operated by the control unit.
• Each auxiliary supply tank contains a suitable substance, either pure or properly diluted, which is to be used together with the liquid solutions of the supply tanks 212a, 212b, 212c, 212d during a corresponding step of the subjected process.
• This configuration determines favourable conditions, in that it allows to mix this substance with the liquid solution each time concerned, in the pre- established percentage and/or weight, so as to affect in the desired way the process steps.
• the control unit 14 cuts off the connection between the container 4 and the outside environment (by means of the electric valve 250) and sets the container 4 in connection with the predetermined auxiliary supply tank, maintaining this connection for a short time. Depression condition inside the container 4 allow in-flowing of the substance coming from the auxiliary supply tank, into the container.
• the substance flow can be determined by a pump 270, which has not been shown, and can be measured by means of a proper meter, also not shown.
• these substances can be supplied to the container either at the same time when the liquid solution 5 is introduced therein, or before liquid solution introduction.
• the substances can be supplied to the container also without the help of the grating 9, in accordance with other ways, which will be obvious to those skilled in the art.
• connection between the container and the auxiliary supply tank is cut off and connection between the container and outside environment is restored.
• the auxiliary supply tanks are associated to the container 4 where process steps are carried out.
• the auxiliary supply tanks can be connected to the containers 4a,4b,4c,4d provided by the different configurations of Figures 5a and 6, as well as to containers 4a,4b,4c,4d,4e,4f shown in Figure 5b, and the substances which they contain are used in a way similar to the one just described.
• Figure 8 concerns a functional-structural feature of the container 4.
• a duct 600 which sets in communication the bottom region of the container 4 with an intermediate region 601 thereof. More precisely, this intermediate region is situated just under the free surface 602 of the liquid solution 5 inside the container.
• a pump is mounted along the duct and operated by the control unit 14, for withdrawing liquid solution from the container 4, at the region 601 , and re- introducing the liquid solution at the bottom. This provokes continuous re- mixing of the liquid substance, thus avoiding, amongst others, settling of solid substances
• numeral 500 indicates a vapour recovery unit
• more recovery units are provided, for instance in number at least equal to the number of steps which form the process carried out inside the container 4
• FIGS. 9a, 9b show only one recovery unit, since the other ones operate exactly in the same way
• This recovery unit includes an electnc valve 404 mounted along a duct 450 which connects the suction means 11 and container inside
• Two pipes 460,479 namely first pipe and second pipe, derive from the duct 450 and have mounted along them, a three-way electric valve 401 and a two-way electric valve 402, respectively
• These pipes cross the tight cover of a condensation vessel 400, under which, at its upper part, there is a baffle 480 arranged inclined
• the first pipe 460 open end is positioned below the inclined baffle, while the second pipe 470 open end is positioned above the baffle
• the bottom of the vessel is connected to the bottom of the container 4, via a piping 490 which has an electric valve 403
• the flow H sucked from the container 4 by the suction means 11 passes through the vessel 400
• This flow is substantially formed by a mix of air (introduced into the container via the ejecting means 9) and vapour formed by the liquid solution 5
• This mix expands in the vessel, getting colder, and great part of the vapour condenses
• the liquid thus obtained is collected at the bottom of the vessel and its level gradually increases.
• a sensor 405 detects when a certain level has been reached and sends a signal to the control unit 14, that determines the operation condition of Figure 9b by operating the above mentioned electric valves.
• the vessel 400 is by-passed, because the valve 404 is on, while the valve 401 sets the vessel inside in communication with the outside environment and the second pipe 470 is cut off by setting the valve 402 off.
• the baffle 480 forms a partition between the air-vapour mix inlet region (first pipe 460) and the air suction region (second pipe 470), so that the minimum amount of vapour which is anyway sent to the suction means is negligible.
• a related recovery unit 500 is further provided with a manifold 410 which sets in communication all the recovery units at one side with the top of the container and at the other side with the bottom of the container, via a related piping 490a.
• a manifold 410 which sets in communication all the recovery units at one side with the top of the container and at the other side with the bottom of the container, via a related piping 490a.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Treatment And Processing Of Natural Fur Or Leather (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Treatment Of Fiber Materials (AREA)
• Electrophonic Musical Instruments (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Toys (AREA)
• Cosmetics (AREA)

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• 1996
  • 1996-05-02 IT IT96BO000233A patent/IT1285917B1/it active IP Right Grant
• 1997
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  • 1997-04-23 CA CA002253486A patent/CA2253486A1/en not_active Abandoned
  • 1997-04-23 EP EP97916590A patent/EP0896635A1/en not_active Withdrawn
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