Title of Invention	"A NOVEL THREE STEPS BIO-PROCESS IN LEATHER PROCESSING"
Abstract	Beam house processes contribute more than 60% of the total pollution from leather processing. The use of lime and sodium sulphide creates a lot of environmental concern. Recently the authors have developed an enzyme-based dehairing assisted with very low amount of sodium sulphide, which completely avoids the use of lime.

Full Text

Field of invention The present invention to a novel eco-friendly bio-process for tanning leather using enzymes. More particularly the present invention provides a process for de-hairing the leather and opening the fibres of the leather during the tanning process by employing commercially available enzyme and without using lime andother alkalis, which is an eco-friendly beam-house process. It is envisaged that the process of the present invention produces leather with equal or better properties . It is also visualized that the softness and grain smoothness of the leather would be improved and the pollution load from this bio-process would be significantly reduced compared to the conventional lime based process which is a multi-step process. Background and prior art references Conventional leather processing involves a number of unit processes and operations namely soaking, liming (dehairing), reliming(fibre opening), deliming, pickling, chrome/vegetable tanning, rechroming, neutralization, retanning.dyeing and fatliquoring. Liming-reliming processes are the inevitable steps in leather processing. The main objectives of liming are the removal of hair, flesh and splitting of fibre bundles by chemical and physical means. To achieve these, lime and sodium sulphide are employed along with substantial quantity of water. Various application methods include pit, paddle, drum and painting on flesh side. Generally, liming-reliming process liquors contribute to 50-70% of the total biochemical oxygen demand (BOD) and chemical oxygen demand (COD) load from a tannery wastewater and 15-20% in the case of total solids (TS) load as reported by Aloy et al ( Tannery and Pollution, Centre Technique Du Cuir: Lyon, France, 1976). Apart from this, a great deal of solid wastes containing lime sludge, fleshings, and hair are generated. The extensive use of sulphide bears unfavorable consequenceson environment and the efficacy of effluent treatment plants as reported by Colleran et al (Antonie van Leeuwenhoek, 67,29, 1995). Several lime and sulphide free liming methods have evolved during the past century. Bose and Dhar (Leather Science, 2, 140, 1955; 21, 39, 1974) have reviewed the use of enzymes such as proteolytic, amylolytic, etc from various sources namely animal, mold, bacterial and plant for dehairing hides and skins. However, these methods include the use of lime Yet another objective of the present invention is to provide a bio based beam-house process that totally obviates the formation of dry sludge. Still another objective of the present invention is to provide a three-step process that provides leathers matching the properties of leathers from conventional leather processing steps. Summary of the invention Accordingly the present invention provides a novel three steps bio-process in leather processing the said process comprises I. applying to raw skins or hides a dehairing paste containing an enzyme either individually or in combination with a dehairing enchancing compound that assists the enzyme. II. seasoning the skins or hides of step (i) for 8-20 hrs. III. de-hairing the skins or hides; IV. applying to the de-haired skin or hide of step (iii) an enzyme either individually or in combination thereof or with an alkali that performs opening up of collagen fibre bundles; V. fleshing followed by washing the skins or hides of step (iv) to obtain clean pelt having cross section pH of from 7.5 to 8.5 , and VI. tanning the skins or hides in the pH of from 7.5 to 8.5 followed by processing to obtain tanned leather. Detailed description of the invention Accordingly the present invention provides a novel three steps bio-process in leather processing the said process comprises: I. applying to raw skins or hides a dehairing paste containing an enzyme either individually or in combination with a dehairing enchancing compound that assists the enzyme. II. seasoning the skins or hides of step (i) for 8-20 hrs. III. de-hairing the skins or hides; IV. applying to the de-haired skin or hide of step (iii) an enzyme either individually or in combination thereof or with an alkali that performs opening up of collagen fibre bundles; V. fleshing followed by washing the skins or hides of step (iv) to obtain clean pelt having cross section pH of from 7.5 to 8.5 , and VI. tanning the skins or hides in the pH of from 7.5 to 8.5 followed by processing to obtain tanned leather. In an embodiment of the present invention, the raw skin or hide used may be selected from wet-salted, dry-salted, dried, green or freezed skins or hides. In another embodiment of the present invention, the known enzyme used for dehairing the skins or hides may be based on bacterial or fungal protease, either individually or in combination. The bacterial and fungal enzyme used are commercially available. Biodart: unhairing enzyme from Southern Petrochemical Industries Corporation Limited alkaline bacterial protease , active a pH 7.5-11 at temperature 25-40°C. Microdep: Unhairing enzyme from Taxan chemicals, alkaline bacterial protease, active at pH 7.5-11 at temperature 25-40°C, powder of 60 mesh. In yet another embodiment of the present invention, the dehairing paste is obtained by mixing 10 to 20 wt% of the enzyme, 0 to 15 wt% of the enhancing compound and 70 to 90 wt% water. In yet another embodiment of the present invention, the de-hairing paste contains 0.5-2.0 wt% of enzyme on the soaked weight of skins or hides. In still another embodiment of the present invention, the dehairing enhancing compound used may be selected from sodium sulphide or sodium sulphydride. In yet another embodiment of the present invention, the de-hairing paste contains 0-1.5 wt% of the enhancing compound on the soaked weight of skins or hides. In still another embodiment of the present invention, the de-hairing paste contains 4-8 wt% of water on the soaked weight of skins or hides. In yet another embodiment of the present invention, the de-hairing paste is applied on flesh or grain side of the hide/skin. In yet another embodiment of the present invention, before applying the de-hairing paste, the skin or hide is soaked in water and is drained for about 10 to about 20 minutes. In yet another embodiment of the present invention, the enzyme used for fibre opening of the dehaired skins or hides may be such as α-amylase, ß-amylase, zymase, maltase, pectinase, elastase, hyaluronidase, a-galactosidase, either individually or in combination. In yet another embodiment of the present invention, the fibre opening of the dehaired skins or hides may be performed using either enzymes such as α-amylase, ß-amylase, zymase, maltase, pectinase, elastase, hyaluronidase, α-galactosidase, either individually or in combination or an alkali such as sodium hydroxide, potassium hydroxide either individually or in combination. In still another embodiment of the present invention, the amount of the enzyme used for fibre opening may be in the range of 0.5 - 2.0 wt% on the dehaired weight of skins or hides. In yet another embodiment of the present invention, the amount of the alkali used for fibre opening may be in the range of 0.3 - 1.25% on the dehaired weight of skins or hides. In yet another embodiment of the present invention, the amount of water used for fibre opening may be in the range of 50 - 350% on the dehaired weight of skins or hides. In yet another embodiment of the present investigation, the duration for the fibre opening may be in the range of 2 - 24 hrs . In yet another embodiment of the present invention, the tanning of the opened up skins or hides may be performed using tanning agents such as basic chromium sulphate, vegetable tannins, chrome syntan, aluminium syntan, chromium-iron tanning agent, chromium-silica tanning agent either alone or in combination with polymeric syntan or other tanning agents. In still another embodiment of the present invention, the amount of the tanning agent used may be in the range of 4 - 10% on the fleshed weight of skins or hides. In still another embodiment of the present invention, the amount of water used for tanning may be in the range of 50 - 150% on the fleshed weight of skins or hides. In yet another embodiment of the present investigation, the duration for the tanning may be in the range of 2 - 10 hrs. In still another embodiment of the present invention, the tanned leathers may be followed by conventional leather processing sequence to obtain leathers for different end use. The process of the present invention is described below in detail. The raw material, skins or hides, is soaked in water conventionally. The weight of the soaked skins or hides is noted after draining for 10 - 15 minutes. A dehairing enzyme or mixture of enzymes in the range of 0.5 - 2.0% on the weight of soaked skins or hides is mixed with a chemical that assists the enzyme in the range of 0 - 1.5% on the weight of soaked skins or hides in 4 - 8% water on the weight of soaked skins or hides to form a paste. The prepared paste is applied on the flesh or grain side of the soaked skins or hides and piled for 8-20 hrs. The skins or hides are then dehaired using a conventional procedure and the weight of the skins or hides is noted down. The dehaired skins or hides are mixed with 50 - 350% water on the weight of dehaired skins or hides conventionally. An enzyme or mixture of enzymes that capable of opening up of fibre bundles is added in the range of 0.5 - 2.0% on the weight of dehaired skins or hides. Alternatively an alkali in the range of 0.3 - 1.25% on the weight of dehaired skins or hides can be used for the same purposeThe duration of fibre opening treatment is in the range of 2 -24 hrs .The opened up skins/hides are fleshed conventionally. The weight of the pelts (skin or hide without hair and flesh) is noted. The cross section pH of the pelts is found to be 7.5 - 8.0. The pelts are tanned using basic chromium sulphate, vegetable tannins, chrome syntan, aluminium syntan, chromium-iron tanning agent, chromium-silica tanning agent in the range of 4 - 10% on the fleshed weight of skins or hides either alone or in combination with polymeric syntan in the range of 0.5 - 2.5% on the fleshed weight of skins or hides or other tanning agents in 50 - 150% water on the fleshed weight of skins or hides. The duration of tanning is in the range of 2 - 10 hrs. The tanned leathers are then followed by conventional leather processing sequence for different end uses. The novelty and non obviousness of the present development lies in using enzymes for dehairing that target hair as well as specific enzymes or alkali for fibre opening that target the cementing substances such as proteoglycans, which facilitates fibre opening. Also, it should be noted that all the aforesaid steps have been accomplished without pH adjustment. Thus this approach forms an eco-friendly bio-based beam house process that aims towards zero waste criteria and more particularly, eliminates the use of lime totally. The invention is described in detail in the following examples, which are provided by way of illustration only and therefore should not be construed to limit the scope of the present invention. Example 1 Three wet salted goatskins, weighing 2.7 kg, were soaked conventionally. The soaked skins were drained to remove surface water and the weight was found to be 3 kg. 30 gms Biodart and 6 gms Microdep C were mixed in 120 ml water along with 6 gms sodium sulphydride to form a paste. The prepared paste was applied on the flesh side of the goatskins and piled flesh side of one skin to flesh side of the other and left undisturbed for 8 hrs. The skins were then dehaired conventionally. Weight of the dehaired skins was found to be 2.8 kg. The dehaired goatskins were loaded in a drum with 2800 ml water. To this, 28 gms α-amylase was added and the drum was run for 4 hrs. The bath was drained off and the skins were scudded and fleshed conventionally. Weight of the pelts was found to be 3.2 kg. Cross section pH of the pelts was found to be 8.0. Example 2 The pelts obtained in Example 1 were washed with 5600 ml water for 10 minutes and drained. Then the pelts were pickled conventionally to a pH 2.8. This was followed by chrome tanning using conventional procedure. The chrome tanned leathers were post tanned to crust upper leathers using a standard recipe. Then the leathers were staked, trimmed and buffed. Example 3 The pelts obtained in Example 1 were washed with 5600 ml water for 10 minutes and drained. A mixture of 16 gms polymeric syntan (developed by Kanthimathi et al for which an Indian Patent has been applied) and 128 gms basic chromium sulphate (BCS) was added to the drum along with 1600 ml water. The drum was run for 2 hrs. The penetration of the chromium was complete and the pH was found to be 4.5. The chrome tanned leathers were post tanned to crust upper leathers using a standard recipe. Then the leathers were staked, trimmed and buffed. Example 4 Three dry salted sheepskins, weighing 4.7 kg, were soaked conventionally. The soaked skins were drained to remove surface water and the weight was found to be 6 kg. 60 gms Biodart was mixed in 300 ml water along with 30 gms sodium sulpide to form a paste. The prepared paste was applied on the flesh side of the sheepskins and piled flesh side of one skin to flesh side of the other and left undisturbed for 10 hrs. The skins were then dehaired conventionally. Weight of the dehaired skins was found to be 4 kg. The dehaired skins were loaded in a drum with 2000 ml water. To this, 15 gms a-amylase, 2 gms zymase and 3 gms pectinase were added and the drum was run for 6 hrs. The bath was drained off and the skins were scudded and fleshed conventionally. Weight of the pelts was found to be 3.5 kg. Cross section pH of the pelts was found to be 7.8. Example 5 The pelts obtained in Example 4 were washed with 7000 ml water for 10 minutes and drained. Then the pelts were partially pickled using conventional procedure to a pH 4.5. This was followed by vegetable tanning using standard procedure. The vegetable tanned leathers were post tanned to crust upper leathers using a standard recipe. Then the leathers were staked, trimmed and buffed. Example 6 The pelts obtained in Example 4 were washed with 7000 ml water for 10 minutes and drained. 180 gms BCS was added to the drum along with 1800 ml water. The drum was run for 3 hrs. The penetration of the chromium was complete and the pH was found to be 4.1. The chrome tanned leathers were post tanned to crust garment leathers using a standard recipe. Then the leathers were staked, trimmed and buffed. Example 7 Four green cow sides, weighing 23 kg, were soaked conventionally. The soaked sides were drained to remove surface water and the weight was found to be 24 kg. 120 gms Biodart was mixed in 1920 ml water along with 360 gms sodium sulphide to form a paste. The prepared paste was applied on the grain side of the cow sides and piled grain side of one side to grain side of the other and left undisturbed for 20 hrs. The sides were then dehaired conventionally. Weight of the dehaired sides was found to be 22 kg. The dehaired sides were loaded in a drum with 33000 ml water. To this, 400 gms a-amylase, 20 gms a-galactosidase and 20 gms maltase were added and the drum was run for 2 hrs. The bath was drained off and the sides were scudded and fleshed conventionally. Weight of the pelts was found to be 26 kg. Cross section pH of the pelts was found to be 8.0. Example 8 The pelts obtained from Example 7 were washed with 52000 ml water for 10 minutes and drained. Then the pelts were pickled conventionally to a pH 2.8. This was followed by chrome tanning using conventional procedure. The chrome tanned leathers were post tanned to crust upper leathers using a standard recipe. Then the leathers were staked, trimmed and buffed. Example 9 The pelts obtained from Example 7 were washed with 52000 ml water for 10 minutes and drained. 2.6 kg chrome syntan (developed by Kanthimathi et al for which an Indian Patent Application has been filed) was added to the drum along with 20800 ml water. The drum was run for 10 hrs. The penetration of the chromium was complete and the pH was found to be 4.2. The chrome tanned leathers were post tanned to crust upholstery leathers using a standard recipe followed for chrome syntan tanned leathers as reported by Suresh et al (Journal of Cleaner Production, 9, 483, 2001). Then the leathers were staked, trimmed and buffed. Example 10 Three dried buffcalfs, weighing 17 kg, were soaked conventionally along with wetting agents. The soaked calfs were drained to remove surface water and the weight was found to be 22 kg. 330 gms Biodart and 110 gms Microdep C were mixed in 1320 ml water to form a paste. The prepared paste was applied on the grain side of the calfs and piled grain side of one calf to grain side of the other and left undisturbed for 18 hrs. The calfskins were dehaired conventionally. Weight of the dehaired calfs was found to be 20 kg. The dehaired calfs were loaded in a drum with 20000 ml water. To this, 200 gms α-amylase, 50 gms hyaluronidase and 50 gms ß-amylase were added and the drum was run for 3 hrs. The bath was drained off and the calfskins were scudded and fleshed conventionally. Weight of the pelts was found to be 24 kg. Cross section pH of the pelts was found to be 7.5. Example 11 The pelts obtained from Example 10 were washed with 48000 ml water for 10 minutes and drained. Then the pelts were pickled conventionally to a pH 2.8. This was followed by chrome tanning using conventional procedure. The chrome tanned leathers were post tanned to crust garment leathers using a standard recipe. Then the leathers were staked, trimmed and buffed. Example 12 The pelts obtained from Example 10 were washed with 48000 ml water for 10 minutes and drained. 2.4 kg wattle extract was added to the drum along with 24000 ml water. The drum was run for 8 hrs. Penetration was complete. Tanned leathers were post tanned to crust aniline upper leathers using a standard recipe. Then the leathers were staked, trimmed, buffed and finished conventionally. Example 13 The pelts obtained from Example 10 were washed with 48000 ml water for 10 minutes and drained. 1.2 kg chromium-silica tanning agent as developed by Thanikaivelan et al (Indian Patent, CSIR Ref. No. NF240/2000, 2000) and 0.7 kg aluminium syntan were added to the drum along with 24000 ml water. The drum was run for 6 hrs. Tanning was complete and the pH was found to be 4.4. Tanned leathers were post tanned to crust garment leathers using a standard recipe. Then the leathers were staked, trimmed and buffed. Example 14 Three dry salted sheepskins, weighing 4.8 kg, were soaked conventionally. The soaked skins were drained to remove surface water and the weight was found to be 6 kg. 60 gms Biodart was mixed in 300 ml water along with 30 gms sodium sulpide to form a paste. The prepared paste was applied on the flesh side of the sheepskins and piled flesh side of one skin to flesh side of the other and left overnight. Next day, the skins were dehaired conventionally. Weight of the dehaired skins was found to be 4 kg. The dehaired skins were loaded in a drum with 14000 ml water. To this, 12 gms sodium hydroxide was added and the drum was run for 30 minutes and left undisturbed for 30 minutes. This was followed by 5 minutes running for each hour for 6 hrs and then left undisturbed for 12 hrs. Next day, the bath was drained off and the skins were fleshed conventionally. Weight of the pelts was found to be 3.6 kg. Cross section pH of the pelts was found to be 8.2. The pelts were washed with 7000 ml water for 10 minutes and drained. 180 gms chromium-iron tanning agent developed by Rao et al (Indian Patent, 446DEL99, 1999) was added to the drum along with 36000 ml water. The drum was run for 3 hrs. Penetration was complete and the pH was found to be 4.4. Tanned leathers were post tanned to crust garment leathers using a standard recipe. Then the leathers were staked, trimmed and buffed. Example 15 Four green cow sides, weighing 24 kg, were soaked conventionally. The soaked sides were drained to remove surface water and the weight was found to be 25 kg. 120 gms Biodart was mixed in 1920 ml water along with 360 gms sodium sulphide to form a paste. The prepared paste was applied on the grain side of the cow sides and piled grain side of one side to grain side of the other and left overnight. Next day, the sides were dehaired conventionally. Weight of the dehaired sides was found to be 22 kg. The dehaired sides were loaded in a drum with 77000 ml water. To this, a mixture of 220 gms sodium hydroxide and 55 gms potassium hydroxide was added and the drum was run for 30 minutes and left undisturbed for 30 minutes. This was followed by 5 minutes running for each hour for 6 hrs and then left undisturbed for 12 hrs. Next day, the bath was drained off and the sides were fleshed using conventional procedure. Weight of the pelts was found to be 26 kg. Cross section pH of the pelts was found to be 8.5. The pelts were washed with 52000 ml water for 10 minutes and drained. 2.34 kg aluminium syntan developed by Kanthimathi et al (Applied for Indian Patent, 2001) was added to the drum along with 26000 ml water. The drum was run for 8 hrs. Tanning was complete and the pH was found to be 4.0. Tanned leathers were post tanned to crust upholstery leathers using a standard recipe. Then the leathers were staked, trimmed and buffed. The following are the advantages of the present invention: 1. This process hardly requires any complicated control measures. 2. The process ensures adequate and optimal fibre opening at pH in the range of 7.5 - 8.5. 3. It completely eliminates the formation of dry sludge. 4. Provides significant reduction in total solids and chemical oxygen demand. 5. The process leads to significant reduction in time, power and water. 6. Provides rationalization of fibre opening processes. 7. Suitable for all kinds of raw materials. 8. This process does not require a deliming step. 9. The product produces soft and supple leathers. 10. Cheaper and commercially available chemicals and enzymes are used for the process of the present invention. 11. This process hardly requires any complicated control measures. 12. The process avoids do-undo principles in leather processing. 13. It completely eliminates the formation of dry sludge. 14. Provides significant reduction in total solids and chemical oxygen demand. 15. The process leads to significant reduction in time, power and water. 16. Suitable for all kinds of raw materials and end products. 17. This process does not require deliming, pickling and basification steps. We Claim: 1. A novel three steps bio-process in leather processing the said process comprises I. applying to raw skins or hides a dehairing paste containing an enzyme either individually or in combination with a dehairing enchancing compound that assists the enzyme. II. seasoning the skins or hides of step (i) for 8-20 hrs. III. de-hairing the skins or hides; IV. applying to the de-haired skin or hide of step (iii) an enzyme either individually or in combination thereof or with an alkali that performs opening up of collagen fibre bundles; V. fleshing followed by washing the skins or hides of step (iv) to obtain clean pelt having cross section pH of from 7.5 to 8.5 , and VI. tanning the skins or hides in the pH of from 7.5 to 8.5 followed by processing to obtain tanned leather. 2. A process as claimed in claim 1 wherein, the said raw skin or hide used is selected from wet-salted, dry-salted, dried, green or freezed skins or hides. 3. A process as claimed in claims 1 to 2 wherein the said enzyme used for dehairing the skins or hides based on bacterial or fungal protease, either individually or in combination. 4. A process as claimed in claims 1 to 3 wherein, the said dehairing paste is obtained by mixing 10 to 20 wt% of enzyme, 0 to 15 wt% of the enhancing compound and 70 to 90wt% water. 5. A process as claimed in claims 1 to 4 wherein, the said de-hairing paste contains 0.5-2.0 wt% of enzyme on the soaked weight of skins or hides. 6. A process as claimed in claims 1 to 5 wherein, the said dehairing enhancing compound used is selected from sodium sulphide or sodium sulphydride. 7. A process as claimed in claims 1 to 6 wherein, the said de-hairing paste contains 0-1.5 wt% of the dehairing enhancing compound on the soaked weight of skins or hides. 8. A process as claimed in claims 1 to 7 wherein, the said de-hairing paste contains 4-8 wt% of water on the soaked weight of skins or hides. 9. A process as claimed in claims 1 to 8 wherein the said de-hairing paste is applied on flesh or grain side of the hide/skin. 10. A process as claimed in claims 1 to 9 wherein, before applying the said de-hairing paste, the skin or hide is soaked in water and is drained for 10 to 20 minutes. 11. A process as claimed in claims 1 to 10 wherein, the fibre opening of the said dehaired skins or hides is performed using either enzymes such as -amylase, -amylase, zymase, maltase, pectinase, elastase, hyaluronidase, -galactosidase, either individually or in combination. 12. A process as claimed in claims 1 to 11 wherein, the fibre opening of the said dehaired skins or hides is performed using either enzymes such as -amylase, -amylase, zymase, maltase, pectinase, elastase, hyaluronidase, -galactosidase, either individually or in combination or an alkali such as sodium hydroxide, potassium hydroxide either individually or in combination process as claimed in claims 1 to 11 wherein, the amount of the enzyme used for fibre opening is in the range of 0.5 -2.0 wt% on the dehaired weight of skins or hides. 13. A process as claimed in claims 1-12 wherein, the amount of the alkali used for fibre opening is in the range of 0.3 - 1.25% on the dehaired weight of skins or hides. 14. A process as claimed in claims 1-13 wherein, the amount of water used for fibre opening is in the range of 50-350% on the dehaired weight of skins or hides. 15. A process as claimed in claims 1 - 14 wherein, the duration for the fibre opening is in the range of 2 - 24 hrs. 16. A process as claimed in claims 1 to 15 wherein, the tanning of the opened up skins or hides may be performed using tanning agents such as basic chromium sulphate, vegetable tannins, chrome syntan, aluminium syntan, chromium-iron tanning agent, chromium -silica tanning agent either alone or in combination with polymeric syntan or other tanning agents.

Documents:

1085-DEL-2002-Abstract-(06-11-2008).pdf

1085-del-2002-abstract.pdf

1085-DEL-2002-Claims-(06-11-2008).pdf

1085-DEL-2002-Claims-(19-09-2008).pdf

1085-del-2002-claims.pdf

1085-DEL-2002-Correspondence-Others-(19-09-2008).pdf

1085-del-2002-correspondence-others.pdf

1085-del-2002-correspondence-po.pdf

1085-DEL-2002-Description (Complete)-(06-11-2008).pdf

1085-DEL-2002-Description (Complete)-(19-09-2008).pdf

1085-del-2002-description (complete).pdf

1085-del-2002-form-1.pdf

1085-del-2002-form-18.pdf

1085-DEL-2002-Form-2-(06-11-2008).pdf

1085-DEL-2002-Form-2-(19-09-2008).pdf

1085-del-2002-form-2.pdf

1085-del-2002-form-3.pdf