EP1386010B1 - Improvements in leather processing - Google Patents

Improvements in leather processing Download PDF

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Publication number
EP1386010B1
EP1386010B1 EP02766642A EP02766642A EP1386010B1 EP 1386010 B1 EP1386010 B1 EP 1386010B1 EP 02766642 A EP02766642 A EP 02766642A EP 02766642 A EP02766642 A EP 02766642A EP 1386010 B1 EP1386010 B1 EP 1386010B1
Authority
EP
European Patent Office
Prior art keywords
leather
process according
enzyme
range
carried out
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP02766642A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP1386010A1 (en
Inventor
Tony Covington
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BLC Leather Technology Centre Ltd
Original Assignee
BLC Leather Technology Centre Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB0110695A external-priority patent/GB0110695D0/en
Application filed by BLC Leather Technology Centre Ltd filed Critical BLC Leather Technology Centre Ltd
Publication of EP1386010A1 publication Critical patent/EP1386010A1/en
Application granted granted Critical
Publication of EP1386010B1 publication Critical patent/EP1386010B1/en
Anticipated expiration legal-status Critical
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Classifications

    • CCHEMISTRY; METALLURGY
    • C14SKINS; HIDES; PELTS; LEATHER
    • C14CCHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
    • C14C3/00Tanning; Compositions for tanning
    • C14C3/02Chemical tanning

Definitions

  • This invention concerns improvements in the processing of animal skins to create leather.
  • the invention results in improved leather quality, in terms of softness, and markedly increased area yield.
  • the invention applies particularly, although not exclusively, to clothing leather and upholstery leather production.
  • the area of a piece of leather and, to a lesser extent, its softness are primarily controlled by structural features of the material from which the leather is made, that is hide or skin.
  • This raw material comprises three main layers which each contribute to the properties of the piece.
  • the flesh layer is the part that was closest to the animal's body. It is composed of collagen fibres that have a distinctly low angle of weave, lying almost parallel to the surfaces of the hide or skin. This means that the layer has limited ability to stretch by distorting the weave horizontally and hence limits the area of the skin or leather.
  • the curium is the middle section and is the thickest part of the original skin. It is composed of a matrix of Interconnecting collagen fibres: in the raw material the fibres have an average angle of weave close to 45°.
  • the weave allows the skin or leather to adopt a larger area, if the angle is lowered by relaxation or straining, or to adopt a smaller area, if the angle of weave is raised during the leather making processes, for example by swelling the pelt.
  • the grain layer is the outermost part of the skin. It has a larger area than the corium and, because it is composed of very fine fibres, it is weaker than the corium, so it adopts a convoluted arrangement, which allows it to stretch without rupturing.
  • the reversibility of the stretching mechanism is made possible by the presence of elastin, a fibrous protein which behaves very much like plastic.
  • the area of the skin or leather is determined by the cerium angle of weave, which in turn is controlled by the area of the flesh layer, if it is present in the leather, and the area of the grain layer, which is usually present in the leather: of the two controlling mechanisms, the more important is the grain.
  • grain leather the grain also limits the softness of the leather, since the presence of the elatin has a stiffening effect.
  • the present invention is based on the finding that mixtures of proteolytic and elastolytic enzymes can be successfully used to improve softness and area yield of leather by treating skins tanned with chromium (III) salts, or aldehydic tanning agents.
  • a process for improving area yield and/or softness of leather which comprises treating chromium (III) or aldehyde tanned skins with an enzyme composition which is a mixture of at least one protease and at least one elastase.
  • Enzyme mixtures containing protease(s) and elastase(s) are commercially available. They are typically derived from bacterial sources in the form of a so-called microbial protease, which in the absence of an expensive purification procedure also contains elastase.
  • the present invention advantageously uses the relatively inexpensive unpurified "protease".
  • An example of en enzyme mixture commercially available is NovoCor® AX (available from Novozymes A/S).
  • elastin possesses an order of magnitude fewer acidic and basic groups on sidechains than collagen and almost double the amount of apolar sidechains.
  • the basis of the invention is that by tanning using chromium (III) salts, chromium (III) is fixed to protein at the acidic side-chains, so the availability of such groups in collagen allows the tannage to work.
  • Part of the definition of the tanning effect is that the protein acquires resistance to microbial attack i.e. putrefaction by the action of proteolytic enzymes.
  • proteolytic enzymes such as those used in the processes leading up to tanning.
  • the lack of acidic groups in elastin means that chrome tanning has little effect on elastin, so there is no conferring of enzymatic resistance.
  • chrome leather leather tanned with chromium (III) salts
  • an enzyme mixture containing an elastase and a protease will result in elastin degradation, but no damage to the collagen and other tanned non-structural proteins.
  • chromium (III) tannage also applies to covalent reaction at the amino groups i.e. by aldehydic tanning reactions, assuming the bound reagent is not released from a polymeric state by hydrolysis.
  • Suitable aldehydic tanning agents include aldehydes themselves, mono- and difunctional, aldehyde derivatives and compounds which have at least partial aldehydic function or reactive hydroxyl function, such as hydroxymethyl phosphonium salts, typically the sulphate or chloride, and especially oxazolidines. It is recognised that not all the potential crosslinkers are acceptable in the workplace because of toxicity hazards. In addition, all derivatives of glutaraldehyde produce leathers which are significantly coloured. Therefore, the preferred crosslinkers are the active-hydroxyl phosphonium salts, which are significantly less toxic than most of the other reagents and produce white leather.
  • tanning reactions that might be used prior to the treatment are likely to result in failure to gain a positive result; such tannages include vegetable tanning with plant polyphenols, syntan and resin tanning. The reason is that these reactions are labile, i.e. reversible, and they rely in some considerable part on forming hydrophobic interactions with the protein.
  • the process of the invention is particularly simple, merely requiring the enzymes to be added to the leather during the normal process of neutralisation prior to conventional post-tanning. Therefore, there is no extra process step involved in the overall treatment of skins to produce leather. This means that the process timing remains unaffected and, importantly, there is no capital cost associated with its introduction. This means that the new process can be applied in all tanneries.
  • the process is remarkably safe, with regard to damaging the leather.
  • the pH of the leather does not have to be high, because the enzyme mixture can be used at a concentration high enough to produce the effect, without the necessity to operate at the pH optimum for the elastase.
  • the resistance of the collagen is high, although it can be damaged, but not until extremely high concentration of protease is used at significantly elevated temperature, e.g. 50°C.
  • Additional aspects of the safety of the process are: the reaction does not have to be prolonged for penetration by the enzyme, because access to the elastin is only a short distance through the grain surface and the elastin does not have to be completely dissolved, it is sufficient to cause significant degradation, so that its function is eliminated.
  • the new technology has the advantage of not being restricted to specific relative activities of elastase and protease in the formulation.
  • the enzymatic reaction may preferably be carried out at a temperature in the range of 35-45°C, more preferably around 40°C, a pH preferably in the range of pH 5-8, more preferably pH 6-7, and a reaction time preferably in the range of 30-180 minutes, more preferably in the range of 60-120 minutes.
  • the enzyme dosage may preferably be in the range of 2-10 kg enzyme product per ton of pelt, more preferably in the range of 3-5 kg enzyme product per ton of pelt.
  • the enzyme product may have an activity measured in Löhlein Volhard Units (LVU) per gram in the range of 50,000 LVU/g to 250,000 LVU/g, preferably 100,000 LVU/g to 150,000 LVU/g.
  • Löhlein Volhard Units Löhlein Volhard Units
  • Löhlein-Volhard unit is the amount of enzyme, which degrades 1.725 mg casein under the conditions set out here.
  • Proteases degrade casein from an alkaline casein solution under the following standard conditions: Temperature 37°C, pH 8.2 and reaction time 60 minutes.
  • the reaction is stopped by adding HCl and non-degraded casein is precipitated with sodium sulphate.
  • the filtrate's content of HCl which is not bound to degraded casein or its degradation products is determined by titration with NaOH. The more casein which is degraded and so non-precipitable, the more acid there will be in the filtrate.
  • the consumption of NaOH in back titration therefore serves as a direct measure of the level of proteolytic activity.
  • the softness and area gains can be achieved without loosening the leather. This is due to two complementary factors. First, the relaxation of the corium is limited by the effects of the tannage, essentially fixing the fibre structure in place, so retaining much of the handle characteristics of the leather. Second, the resistance of the protein to proteolytic attack means that the non-structural protein is not removed nor is the collagen dissolved, so the filling of the fibre structure is maintained. Importantly, that resistance to degradation includes the grain-corium junction, where damage is seen as a loosening of the layers, resulting in poor break, i.e. coarse rippling of the grain surface when the leather is bent. The maintaining of the 'tight' structure is a vital quality determining factor in the finished leather.
  • German bovine wetblue 1.1-1.2 mm

Landscapes

  • 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)
EP02766642A 2001-05-01 2002-04-26 Improvements in leather processing Expired - Lifetime EP1386010B1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
GB0110695 2001-05-01
GB0110695A GB0110695D0 (en) 2001-05-01 2001-05-01 Improvements in leather processing
DKPA200101798 2001-12-04
DK200101798 2001-12-04
PCT/EP2002/004635 WO2002088397A1 (en) 2001-05-01 2002-04-26 Improvements in leather processing

Publications (2)

Publication Number Publication Date
EP1386010A1 EP1386010A1 (en) 2004-02-04
EP1386010B1 true EP1386010B1 (en) 2011-01-26

Family

ID=26069106

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02766642A Expired - Lifetime EP1386010B1 (en) 2001-05-01 2002-04-26 Improvements in leather processing

Country Status (12)

Country Link
EP (1) EP1386010B1 (tr)
KR (1) KR100871597B1 (tr)
CN (1) CN1273619C (tr)
AR (1) AR049240A1 (tr)
AT (1) ATE497024T1 (tr)
AU (1) AU2002308063B2 (tr)
BR (1) BR0209303B1 (tr)
DE (1) DE60239055D1 (tr)
MX (1) MXPA03009853A (tr)
NZ (1) NZ529172A (tr)
TR (1) TR200301830T2 (tr)
WO (1) WO2002088397A1 (tr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101307368B (zh) * 2008-07-01 2012-03-21 中国科学院昆明动物研究所 用于制作亚洲象姿态标本的象皮处理方法
CN102002541B (zh) * 2010-05-24 2013-04-24 孟凡标 一种栲胶鞣毛革一体工艺
CN102827967A (zh) * 2012-09-14 2012-12-19 兴业皮革科技股份有限公司 一种增大皮革面积得率的方法
CN107619892A (zh) * 2016-07-15 2018-01-23 北京市纺织纤维检验所 一种稳定无铬皮革面积的处理方法
US12421563B2 (en) 2019-10-30 2025-09-23 Kao Corporation Leather improving agent

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4035839A1 (de) * 1990-11-10 1992-05-14 Roehm Gmbh Protease als wirkenzym enthaltende, tensidfreie feste enzympraeparate
DE4439990A1 (de) 1994-11-09 1996-05-15 Bayer Ag Ledergerbstoffe und Stellmittel für Farstoffe
RU2096466C1 (ru) * 1996-06-25 1997-11-20 Центральный научно-исследовательский институт кожевенно-обувной промышленности Способ обработки кожевенного сырья
RU2114917C1 (ru) * 1996-07-16 1998-07-10 Татьяна Флавиановна Миронова Способ обработки шкурок кролика
US6340458B1 (en) * 1999-11-19 2002-01-22 Reva Amir Use of enzymes for skin expansion
JP4114046B2 (ja) * 2002-07-12 2008-07-09 川村通商株式会社 酵素脱毛処理剤および酵素脱毛法

Also Published As

Publication number Publication date
AR049240A1 (es) 2006-07-12
NZ529172A (en) 2005-09-30
TR200301830T2 (tr) 2004-12-21
EP1386010A1 (en) 2004-02-04
KR100871597B1 (ko) 2008-12-02
AU2002308063B2 (en) 2007-10-25
WO2002088397A1 (en) 2002-11-07
ATE497024T1 (de) 2011-02-15
DE60239055D1 (de) 2011-03-10
BR0209303A (pt) 2004-06-15
MXPA03009853A (es) 2004-12-06
KR20040015233A (ko) 2004-02-18
CN1273619C (zh) 2006-09-06
CN1505686A (zh) 2004-06-16
BR0209303B1 (pt) 2011-10-04

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