NZ624685B - Method of depilation - Google Patents
Method of depilationInfo
- Publication number
- NZ624685B NZ624685B NZ624685A NZ62468514A NZ624685B NZ 624685 B NZ624685 B NZ 624685B NZ 624685 A NZ624685 A NZ 624685A NZ 62468514 A NZ62468514 A NZ 62468514A NZ 624685 B NZ624685 B NZ 624685B
- Authority
- NZ
- New Zealand
- Prior art keywords
- skin
- hide
- contacting
- composition
- enzyme
- Prior art date
Links
- 230000035617 depilation Effects 0.000 title description 45
- 210000003491 Skin Anatomy 0.000 claims abstract description 515
- 239000000203 mixture Substances 0.000 claims abstract description 152
- 102000004190 Enzymes Human genes 0.000 claims abstract description 143
- 108090000790 Enzymes Proteins 0.000 claims abstract description 143
- 230000003213 activating Effects 0.000 claims abstract description 72
- 230000002951 depilatory Effects 0.000 claims abstract description 59
- 239000003223 protective agent Substances 0.000 claims abstract description 57
- 210000002268 Wool Anatomy 0.000 claims abstract description 56
- 210000004209 Hair Anatomy 0.000 claims abstract description 50
- 239000011780 sodium chloride Substances 0.000 claims abstract description 21
- 150000003839 salts Chemical class 0.000 claims abstract description 18
- FAUOSXUSCVJWAY-UHFFFAOYSA-N tetrakis(hydroxymethyl)phosphanium Chemical class OC[P+](CO)(CO)CO FAUOSXUSCVJWAY-UHFFFAOYSA-N 0.000 claims abstract description 11
- PQJIXFVXQRCTKI-UHFFFAOYSA-N OCP(CO)(CO)CO Chemical class OCP(CO)(CO)CO PQJIXFVXQRCTKI-UHFFFAOYSA-N 0.000 claims abstract description 10
- WYNCHZVNFNFDNH-UHFFFAOYSA-N oxazolidine Chemical compound C1COCN1 WYNCHZVNFNFDNH-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000003795 chemical substances by application Substances 0.000 claims description 97
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 79
- 230000003472 neutralizing Effects 0.000 claims description 64
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 57
- GRVFOGOEDUUMBP-UHFFFAOYSA-N Sodium sulfide Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 claims description 52
- 229910052979 sodium sulfide Inorganic materials 0.000 claims description 52
- 239000010985 leather Substances 0.000 claims description 46
- 238000000034 method Methods 0.000 claims description 42
- 238000005406 washing Methods 0.000 claims description 38
- 239000000463 material Substances 0.000 claims description 35
- 239000002253 acid Substances 0.000 claims description 34
- YIEDHPBKGZGLIK-UHFFFAOYSA-L tetrakis(hydroxymethyl)phosphanium;sulfate Chemical compound [O-]S([O-])(=O)=O.OC[P+](CO)(CO)CO.OC[P+](CO)(CO)CO YIEDHPBKGZGLIK-UHFFFAOYSA-L 0.000 claims description 34
- BDAGIHXWWSANSR-UHFFFAOYSA-N formic acid Chemical compound OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 33
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium monoxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 32
- XMGQYMWWDOXHJM-JTQLQIEISA-N (4R)-limonene Natural products CC(=C)[C@@H]1CCC(C)=CC1 XMGQYMWWDOXHJM-JTQLQIEISA-N 0.000 claims description 29
- PMZURENOXWZQFD-UHFFFAOYSA-L na2so4 Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 26
- 239000003961 penetration enhancing agent Substances 0.000 claims description 25
- 230000000694 effects Effects 0.000 claims description 23
- 239000003431 cross linking reagent Substances 0.000 claims description 22
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 22
- 235000011152 sodium sulphate Nutrition 0.000 claims description 22
- 238000005554 pickling Methods 0.000 claims description 21
- 150000003568 thioethers Chemical class 0.000 claims description 19
- 108090000787 Subtilisin Proteins 0.000 claims description 16
- 239000000292 calcium oxide Substances 0.000 claims description 16
- 102000004169 proteins and genes Human genes 0.000 claims description 15
- 108090000623 proteins and genes Proteins 0.000 claims description 15
- CZMRCDWAGMRECN-GDQSFJPYSA-N Sucrose Natural products O([C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@H](CO)O1)[C@@]1(CO)[C@H](O)[C@@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-GDQSFJPYSA-N 0.000 claims description 13
- CWERGRDVMFNCDR-UHFFFAOYSA-N Thioglycolic acid Chemical compound OC(=O)CS CWERGRDVMFNCDR-UHFFFAOYSA-N 0.000 claims description 13
- 239000005720 sucrose Substances 0.000 claims description 13
- CZMRCDWAGMRECN-UGDNZRGBSA-N D-sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 claims description 12
- UXVMQQNJUSDDNG-UHFFFAOYSA-L cacl2 Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 12
- 239000001110 calcium chloride Substances 0.000 claims description 12
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 12
- 238000005238 degreasing Methods 0.000 claims description 11
- 235000019253 formic acid Nutrition 0.000 claims description 11
- 150000001875 compounds Chemical class 0.000 claims description 10
- 241000502561 Acacia irrorata Species 0.000 claims description 9
- 101700033607 ASPR Proteins 0.000 claims description 8
- 101710006981 EN45_076310 Proteins 0.000 claims description 8
- 101700046746 PEN13 Proteins 0.000 claims description 8
- 101700073521 PENC1 Proteins 0.000 claims description 8
- 229940046307 SODIUM THIOGLYCOLATE Drugs 0.000 claims description 6
- GNBVPFITFYNRCN-UHFFFAOYSA-M sodium thioglycolate Chemical compound [Na+].[O-]C(=O)CS GNBVPFITFYNRCN-UHFFFAOYSA-M 0.000 claims description 6
- 125000000545 (4R)-limonene group Chemical group 0.000 claims description 3
- XGZRAKBCYZIBKP-UHFFFAOYSA-L disodium;dihydroxide Chemical compound [OH-].[OH-].[Na+].[Na+] XGZRAKBCYZIBKP-UHFFFAOYSA-L 0.000 claims description 3
- 239000004367 Lipase Substances 0.000 abstract description 7
- 102000004882 lipase Human genes 0.000 abstract description 7
- 108090001060 lipase Proteins 0.000 abstract description 7
- 235000019421 lipase Nutrition 0.000 abstract description 7
- 102000005158 Subtilisins Human genes 0.000 abstract 2
- 108010056079 Subtilisins Proteins 0.000 abstract 2
- 229940088598 Enzyme Drugs 0.000 description 115
- 239000002585 base Substances 0.000 description 29
- 239000007864 aqueous solution Substances 0.000 description 20
- 239000000243 solution Substances 0.000 description 19
- 238000011065 in-situ storage Methods 0.000 description 14
- 239000003973 paint Substances 0.000 description 14
- 230000020477 pH reduction Effects 0.000 description 13
- 239000003153 chemical reaction reagent Substances 0.000 description 12
- 239000003638 reducing agent Substances 0.000 description 12
- 230000001264 neutralization Effects 0.000 description 11
- 235000000346 sugar Nutrition 0.000 description 11
- 108091005650 Basic proteases Proteins 0.000 description 10
- NOOLISFMXDJSKH-KXUCPTDWSA-N (-)-(1R,3R,4S)-menthol Chemical compound CC(C)[C@@H]1CC[C@@H](C)C[C@H]1O NOOLISFMXDJSKH-KXUCPTDWSA-N 0.000 description 9
- QTBSBXVTEAMEQO-UHFFFAOYSA-N acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 9
- 241000283898 Ovis Species 0.000 description 8
- MHAJPDPJQMAIIY-UHFFFAOYSA-N hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 8
- 150000003505 terpenes Chemical group 0.000 description 8
- AXCZMVOFGPJBDE-UHFFFAOYSA-L Calcium hydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 7
- 235000015450 Tilia cordata Nutrition 0.000 description 7
- 235000011941 Tilia x europaea Nutrition 0.000 description 7
- 230000004913 activation Effects 0.000 description 7
- 239000000920 calcium hydroxide Substances 0.000 description 7
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 7
- 239000004571 lime Substances 0.000 description 7
- 230000035515 penetration Effects 0.000 description 7
- DGVVWUTYPXICAM-UHFFFAOYSA-N 2-mercaptoethanol Chemical compound OCCS DGVVWUTYPXICAM-UHFFFAOYSA-N 0.000 description 6
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 6
- 108010059378 Endopeptidases Proteins 0.000 description 6
- 102000005593 Endopeptidases Human genes 0.000 description 6
- 102000035443 Peptidases Human genes 0.000 description 6
- 108091005771 Peptidases Proteins 0.000 description 6
- 230000002378 acidificating Effects 0.000 description 6
- 235000019270 ammonium chloride Nutrition 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- QDHHCQZDFGDHMP-UHFFFAOYSA-N monochloramine Chemical compound ClN QDHHCQZDFGDHMP-UHFFFAOYSA-N 0.000 description 6
- 238000010422 painting Methods 0.000 description 6
- 238000002203 pretreatment Methods 0.000 description 6
- 235000019833 protease Nutrition 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- XMGQYMWWDOXHJM-UHFFFAOYSA-N (+-)-(RS)-limonene Chemical compound CC(=C)C1CCC(C)=CC1 XMGQYMWWDOXHJM-UHFFFAOYSA-N 0.000 description 5
- 229960004873 LEVOMENTHOL Drugs 0.000 description 5
- 229940040461 Lipase Drugs 0.000 description 5
- 229940041616 Menthol Drugs 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 5
- 230000002255 enzymatic Effects 0.000 description 5
- 229930007650 limonene Natural products 0.000 description 5
- 235000001510 limonene Nutrition 0.000 description 5
- 229940087305 limonene Drugs 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 238000005507 spraying Methods 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L sulfate group Chemical group S(=O)(=O)([O-])[O-] QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 5
- TUBQDCKAWGHZPF-UHFFFAOYSA-N 1,3-benzothiazol-2-ylsulfanylmethyl thiocyanate Chemical compound C1=CC=C2SC(SCSC#N)=NC2=C1 TUBQDCKAWGHZPF-UHFFFAOYSA-N 0.000 description 4
- 102000008186 Collagen Human genes 0.000 description 4
- 108010035532 Collagen Proteins 0.000 description 4
- GUBGYTABKSRVRQ-YOLKTULGSA-N Maltose Natural products O([C@@H]1[C@H](O)[C@@H](O)[C@H](O)O[C@H]1CO)[C@@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 GUBGYTABKSRVRQ-YOLKTULGSA-N 0.000 description 4
- KJFMBFZCATUALV-UHFFFAOYSA-N Phenolphthalein Chemical compound C1=CC(O)=CC=C1C1(C=2C=CC(O)=CC=2)C2=CC=CC=C2C(=O)O1 KJFMBFZCATUALV-UHFFFAOYSA-N 0.000 description 4
- 239000003513 alkali Substances 0.000 description 4
- 150000001450 anions Chemical class 0.000 description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- 229910052791 calcium Inorganic materials 0.000 description 4
- 230000024881 catalytic activity Effects 0.000 description 4
- 229960005188 collagen Drugs 0.000 description 4
- 229920001436 collagen Polymers 0.000 description 4
- 230000001939 inductive effect Effects 0.000 description 4
- 230000037368 penetrate the skin Effects 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N sulfur Chemical group [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 4
- 235000007586 terpenes Nutrition 0.000 description 4
- 240000008602 Eucalyptus cornuta Species 0.000 description 3
- 241000282320 Panthera leo Species 0.000 description 3
- 239000004365 Protease Substances 0.000 description 3
- FEPYBFUCUKJIIL-UHFFFAOYSA-L S(=O)(=O)([O-])[O-].O[PH3+].O[PH3+] Chemical compound S(=O)(=O)([O-])[O-].O[PH3+].O[PH3+] FEPYBFUCUKJIIL-UHFFFAOYSA-L 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-K [O-]P([O-])([O-])=O Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 3
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 3
- GRWVQDDAKZFPFI-UHFFFAOYSA-H chromium(III) sulfate Chemical compound [Cr+3].[Cr+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O GRWVQDDAKZFPFI-UHFFFAOYSA-H 0.000 description 3
- 210000001208 inner root sheath cell Anatomy 0.000 description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 3
- 150000007524 organic acids Chemical class 0.000 description 3
- 239000010452 phosphate Substances 0.000 description 3
- 230000017854 proteolysis Effects 0.000 description 3
- 230000002797 proteolythic Effects 0.000 description 3
- 159000000000 sodium salts Chemical group 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 239000001117 sulphuric acid Substances 0.000 description 3
- 235000011149 sulphuric acid Nutrition 0.000 description 3
- KUXGUCNZFCVULO-UHFFFAOYSA-N 2-(4-nonylphenoxy)ethanol Chemical compound CCCCCCCCCC1=CC=C(OCCO)C=C1 KUXGUCNZFCVULO-UHFFFAOYSA-N 0.000 description 2
- GZCGUPFRVQAUEE-KCDKBNATSA-N D-(+)-Galactose Natural products OC[C@@H](O)[C@H](O)[C@H](O)[C@@H](O)C=O GZCGUPFRVQAUEE-KCDKBNATSA-N 0.000 description 2
- WQZGKKKJIJFFOK-GASJEMHNSA-N D-Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 2
- MNQZXJOMYWMBOU-UHFFFAOYSA-N Glyceraldehyde Chemical compound OCC(O)C=O MNQZXJOMYWMBOU-UHFFFAOYSA-N 0.000 description 2
- 210000003780 Hair Follicle Anatomy 0.000 description 2
- GUBGYTABKSRVRQ-UUNJERMWSA-N Lactose Natural products O([C@@H]1[C@H](O)[C@H](O)[C@H](O)O[C@@H]1CO)[C@H]1[C@@H](O)[C@@H](O)[C@H](O)[C@H](CO)O1 GUBGYTABKSRVRQ-UUNJERMWSA-N 0.000 description 2
- 210000001138 Tears Anatomy 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 230000003115 biocidal Effects 0.000 description 2
- 239000003139 biocide Substances 0.000 description 2
- CPELXLSAUQHCOX-UHFFFAOYSA-M bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 2
- 230000001680 brushing Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000005237 degreasing agent Methods 0.000 description 2
- 150000002016 disaccharides Chemical class 0.000 description 2
- 239000003925 fat Substances 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 2
- 230000000855 fungicidal Effects 0.000 description 2
- 239000000417 fungicide Substances 0.000 description 2
- 239000008103 glucose Substances 0.000 description 2
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N glutaraldehyde Chemical compound O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000008101 lactose Substances 0.000 description 2
- GUBGYTABKSRVRQ-XLOQQCSPSA-N lactose Chemical compound O[C@@H]1[C@@H](O)[C@@H](O)[C@@H](CO)O[C@H]1O[C@@H]1[C@@H](CO)O[C@H](O)[C@H](O)[C@H]1O GUBGYTABKSRVRQ-XLOQQCSPSA-N 0.000 description 2
- 230000000670 limiting Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 230000000813 microbial Effects 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006011 modification reaction Methods 0.000 description 2
- 239000003607 modifier Substances 0.000 description 2
- 150000002772 monosaccharides Chemical class 0.000 description 2
- 229920000847 nonoxynol Polymers 0.000 description 2
- -1 nonyl phenyl Chemical group 0.000 description 2
- 230000002633 protecting Effects 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000010186 staining Methods 0.000 description 2
- 238000010561 standard procedure Methods 0.000 description 2
- 230000002522 swelling Effects 0.000 description 2
- AKXUUJCMWZFYMV-UHFFFAOYSA-M tetrakis(hydroxymethyl)phosphanium;chloride Chemical compound [Cl-].OC[P+](CO)(CO)CO AKXUUJCMWZFYMV-UHFFFAOYSA-M 0.000 description 2
- WQZGKKKJIJFFOK-PHYPRBDBSA-N α-D-galactose Chemical compound OC[C@H]1O[C@H](O)[C@H](O)[C@@H](O)[C@H]1O WQZGKKKJIJFFOK-PHYPRBDBSA-N 0.000 description 2
- WQZGKKKJIJFFOK-VFUOTHLCSA-N β-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 2
- 241000282994 Cervidae Species 0.000 description 1
- 210000003298 Dental Enamel Anatomy 0.000 description 1
- 210000004207 Dermis Anatomy 0.000 description 1
- 235000019749 Dry matter Nutrition 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 210000002615 Epidermis Anatomy 0.000 description 1
- 229920000881 Modified starch Polymers 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 238000001994 activation Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive Effects 0.000 description 1
- 150000003842 bromide salts Chemical class 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 159000000007 calcium salts Chemical group 0.000 description 1
- 210000004027 cells Anatomy 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000004059 degradation Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- HQWKKEIVHQXCPI-UHFFFAOYSA-L disodium;phthalate Chemical compound [Na+].[Na+].[O-]C(=O)C1=CC=CC=C1C([O-])=O HQWKKEIVHQXCPI-UHFFFAOYSA-L 0.000 description 1
- 230000002500 effect on skin Effects 0.000 description 1
- 230000002708 enhancing Effects 0.000 description 1
- 238000006047 enzymatic hydrolysis reaction Methods 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 150000004673 fluoride salts Chemical class 0.000 description 1
- 159000000011 group IA salts Chemical class 0.000 description 1
- RDBMUARQWLPMNW-UHFFFAOYSA-O hydroxymethylphosphanium Chemical class OC[PH3+] RDBMUARQWLPMNW-UHFFFAOYSA-O 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 229910000403 monosodium phosphate Inorganic materials 0.000 description 1
- 235000019799 monosodium phosphate Nutrition 0.000 description 1
- TVPFLPJBESCUKI-UHFFFAOYSA-M potassium;N,N-dimethylcarbamodithioate Chemical compound [K+].CN(C)C([S-])=S TVPFLPJBESCUKI-UHFFFAOYSA-M 0.000 description 1
- 210000004918 root sheath Anatomy 0.000 description 1
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000003068 static Effects 0.000 description 1
- 125000000185 sucrose group Chemical group 0.000 description 1
- 150000008163 sugars Chemical class 0.000 description 1
- 125000003396 thiol group Chemical group [H]S* 0.000 description 1
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
- C14C1/00—Chemical treatment prior to tanning
- C14C1/06—Facilitating unhairing, e.g. by painting, by liming
- C14C1/065—Enzymatic unhairing
Abstract
Provided is a method for removing wool or hair from at least one raw skin or hide prior to tanning, the skin or hide having a flesh side and a grain side, comprising: a) contacting the skin or hide with a composition comprising a protective agent, b) contacting the skin or hide with a composition comprising a depilatory enzyme, c) contacting the skin or hide with an activating composition, wherein the activating composition activates the depilatory enzyme in b) to act on the depilatory active structures in the skin or hide, and d) removing the wool or hair from the skin or hide. The preferred protective agents include tetrakis(hydroxymethyl)phosphine compounds (THP), tetrakis(hydroxymethyl)phosphonium salts (THP salts), tetrakis(hydroxymethyl)phosphine condensates (THP condensates) and oxazolidine. The preferred enzymes used include subtilisins and lipases. comprising a depilatory enzyme, c) contacting the skin or hide with an activating composition, wherein the activating composition activates the depilatory enzyme in b) to act on the depilatory active structures in the skin or hide, and d) removing the wool or hair from the skin or hide. The preferred protective agents include tetrakis(hydroxymethyl)phosphine compounds (THP), tetrakis(hydroxymethyl)phosphonium salts (THP salts), tetrakis(hydroxymethyl)phosphine condensates (THP condensates) and oxazolidine. The preferred enzymes used include subtilisins and lipases.
Description
METHOD OF DEPILATION
TECHNICAL FIELD
The present invention relates generally to methods for removing wool or hair from hides or skins
using enzymes wholly without sodium sulfide or with levels of sodium sulfide normally considered
too low for successful unhairing. The invention also relates generally to compositions for use in the
methods.
BACKGROUND OF THE INVENTION
The leather industry has long been interested in enzyme depilation of skins and hides with
comprehensive reviews of enzyme depilation appearing every few decades (Green, 1952), (Yates,
1972), (Brady et al., 1989), (Cantera, 2001). Continued interest in the subject (Sivasubramanian et
al., 2008), (Wang et al, 2009) supports the assertion that there is a widespread desire to use enzymes
as the means of depilating skins or hides. Enzymes are desirable for use as an alternative to
conventional lime and sodium sulfide processing because conventional lime and sodium sulfide
processing is hazardous and unpleasant. Conventional processing is used to generate high quality
leather. Accordingly, alternatives to conventional lime and sodium sulfide processing needs to
provide leather of the same or similar quality, or will not be generally acceptable.
Wholly enzyme based depilation processes have been described that purport to be successful
(Macedo et al., 2005), (Sivasubramanian et al., 2008), (Saravanabhavan et al., 2005), (Rose et al.,
2007). However, problems have been reported when ostensibly successful methods have been
trialled under temperate conditions (10-20°C) (Lowe, 1999), (Lowe, 2000), (Cooper & Lowe,
1997), (Cooper, 1997). Several patents are directed to enzyme-based, sulfide-free depilation
methods, including WO2005/049871 and US 7,198,647. However, the quality of the leather
produced by the methods disclosed in WO2005/049871 and US 7,198,647 is not discussed.
2
Moreover, the methods disclosed in WO2005/049871 and US 7,198,647 differ from the methods of
the present invention in several important respects.
No enzyme depilation system has yet achieved a level of performance approaching that of the
traditional lime and sodium sulfide process (Edmonds, 2012). Briefly; the major problems with
presently used conventional methods are: incomplete depilation requiring additional sulfide based
processing; damage to the grain surface resulting in a nubuck effect; and looseness. Looseness is a
fault in the leather in which the internal structure appears to lose its elasticity, and manifests itself as
surface creasing when the leather is folded inwardly (Coulson, 1969). Although enzymes are
known that are able to depilate sheep skins (Yates, 1972), the resulting skins lack the quality of
conventionally processed skins and the process is not used commercially.
The mechanisms of depilation are partially understood (Cantera, 2001a), (Cantera, 2001b),
(Cantera, 2001c), (Cantera, 2001d), (Brady et al., 1989b). However, as described above, the
unsatisfactory effects of the enzymes used in known enzymatic depilation regimes results in
unwanted damage to skins and ultimately, low quality leather (Wang et al., 2005),(Felicjaniak, B.,
1985),(Tandt, H., et al, 1997),(Defect processing BLC leather technologies centre, 2001),(Hawkins,
S., and J. Wassenberg, J., 1997)There is a need to develop enzyme based depilation methods,
particularly methods that can be used industrially, that result in a consistent high quality leather.
It is an object of the invention to go at least some way towards avoiding the above disadvantages
and/or that at least provides the public with a useful choice.
In this specification where reference has been made to patent specifications, other external
documents, or other sources of information, this is generally for the purpose of providing a context
for discussing the features of the invention. Unless specifically stated otherwise, reference to such
external documents is not to be construed as an admission that such documents, or such sources of
3
information, in any jurisdiction, are prior art, or form part of the common general knowledge in the
art.
SUMMARY OF THE INVENTION
In a first aspect the invention relates to a method for removing wool or hair from at least one raw
skin or hide, the skin or hide having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with a composition comprising a protective agent,
b) contacting the skin or hide with a composition comprising a depilatory enzyme that is active
at an alkaline pH greater than about 8,
c) contacting the skin or hide with an activating composition comprising a base and a
deswelling agent, wherein the base activates the depilatory enzyme in b) to act on the
depilatory active structures in the skin or hide, and
d) removing the wool or hair from the skin or hide.
In one embodiment the method further comprises
e) neutralizing the base on and/or in the skin or hide.
In one embodiment the method further comprises
f) washing the skin or hide with water between step a) and step b).
In one embodiment of the method removing the wool or hair from the skin or hide is carried out
after neutralizing the base on and/or in the skin or hide.
In one embodiment the method further comprises
4
g) removing a neutralizing agent that has been used to neutralize the base on and/or in the skin
or hide.
In one embodiment the method further comprises
h) washing the skin or hide in water after step g).
In one embodiment the method further comprises
i) processing the skin or hide using conventional deliming and then pickling techniques to
produce pickled skin or pickled hide.
In one embodiment the method comprises
j) as an alternative to (i) the steps of degreasing the skin or hide followed by processing the
skin or hide directly to wet blue without a pickling step.
In one embodiment the method further comprises
k) processing the pickled or wet blue skin or hide into leather.
In a second aspect the invention relates to a method for removing wool or hair from at least one raw
skin or hide, the skin or hide having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with a composition comprising a tetrakis (hydroxymethyl)
phosphine (THP) compound, a tetrakis (hydroxymethyl) phosphonium salt (a THP salt), a
THP condensate, or oxazolidine,
b) contacting the skin or hide with a composition comprising an alkaline serine protease in a
substantially inactive state,
c) contacting the skin or hide with an activating composition comprising hydrated calcium
oxide, thioglycolic acid, sodium sulfate and sodium hydroxide to activate the alkaline serine
protease in b), and
d) removing the wool or hair from the skin or hide.
In one embodiment the method further comprises
e) contacting the skin or hide with a neutralizing agent comprising sucrose and calcium
chloride to reduce the pH on and/or in the skin or hide.
In one embodiment the method comprises
f) washing the skin or hide with water between step a) and step b).
In a third aspect the invention relates to a method for removing wool or hair from at least one raw
skin or hide, the skin or hide each having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with a composition comprising a protein cross-linking agent,
b) contacting the skin or hide with a composition comprising a depilatory enzyme that is
substantially inactive at the pH of the composition,
c) contacting the skin or hide with an activating composition comprising an agent that activates
the depilatory enzyme in b), and a deswelling agent, and
d) removing the wool or hair from the skin or hide.
In one embodiment the method comprises
e) washing the skin or hide with water between step a) and step b).
6
In one embodiment the contacting in c) is contacting the flesh side of the skin or hide with the
activating composition.
In a fourth aspect the invention relates to a method for removing wool or hair from at least one skin
or hide, the skin or hide each having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with a composition comprising a protein cross-linking agent,
b) contacting the skin or hide with a composition comprising a depilatory enzyme under
conditions that maintain the enzyme in a substantially inactive state,
c) contacting the flesh side of the skin or hide with an activating composition comprising an
activating agent to activate the depilatory enzyme in b), and
d) removing the wool or hair from the skin or hide.
In one embodiment the method comprises
e) washing the skin or hide with water between step a) and step b).
In one embodiment of the method the activating composition in c) comprises a deswelling agent.
In a fifth aspect the invention relates to a method for removing wool or hair from at least one raw
skin or hide, the skin or hide having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with an composition comprising a protective agent,
b) contacting the skin or hide with a composition comprising a depilatory enzyme that is active
at an alkaline pH,
7
c) contacting the flesh side of the skin or hide with an activating composition comprising a
base and a deswelling agent, wherein the base activates the depilatory enzyme in b) to act on
the depilatory active structures in the skin or hide, and
d) removing the wool or hair from the skin or hide,
wherein the method either i) does not use a sulfide, or ii), uses sodium sulfide at concentrations of
less than about 1% Na2S (gNa2S/gSkin material).
In one embodiment the further comprises
e) washing the skin or hide with water between step a) and step b).
In one embodiment of the method, ii) uses sodium sulfide at a concentration of about 0.5 to about
0.9% gNa2S/gSkin material, preferably about 0.7% gNa2S/gSkin material.
In one embodiment the method of any of the first through fourth aspects either i) does not use
sulfide or ii) uses sulfide at a concentration of less than about 1% Na2S (gNa2S/gSkin material).
In a sixth aspect the invention relates to a method for removing wool or hair from at least one raw
skin or hide, the skin or hide having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with a composition comprising about 2% tetrakis
(hydroxymethyl) phosphonium sulfate (THPS) (wtTHPS/wtSkin material) for about three
hours,
b) contacting the skin or hide for about 2 hours with a composition comprising about 2%
wt/vol of a depilatory enzyme subtilisin having an activity of 0.5AU/min, the composition
having a pH of about 7,
8
c) contacting the skin or hide for about 2 to about 16 hours with an activating composition
comprising about 5% hydrated calcium oxide (wt/vol), about 3% thioglycolic acid (wt/vol),
about 0.5% sodium sulfate (wt/vol) and about 10% sodium hydroxide (wt/vol) to activate
the subtilisin,
d) removing the wool or hair from the skin or hide.
In one embodiment the method of the sixth aspect further comprises the step of neutralizing the
base on and/or in the skin or hide by contacting the skin or hide for about 2 hours with a
neutralizing agent comprising sucrose and calcium chloride.
In one embodiment the method of the sixth aspect further comprises the step of removing a
neutralizing agent that has been used to neutralize the base on and/or in the skin or hide.
In one embodiment the method of the sixth aspect further comprises the step of washing the skin or
hide in water between steps a) and b) or after step g) or both.
In one embodiment the method of the sixth aspect further comprises the step of processing the skin
or hide using conventional deliming and then pickling techniques to produce pickled skin or pickled
hide.
In one alternative embodiment the method of the sixth aspect comprises the step of degreasing the
skin or hide followed by processing the skin or hide directly to wet blue without a pickling step.
In one embodiment the method of the sixth aspect further comprises the step of processing the
pickled or wet blue skin or hide into leather.
In one embodiment the method of the sixth aspect either i) does not use sulfide or ii) uses sodium
sulfide at a concentration of about 0.7% (gNa2S/gSkin material).
9
In one embodiment the method of any of the preceding aspects comprises, before a), contacting the
skin or hide with a composition comprising an acid. Preferably the acid is an organic acid,
preferably a carboxylic acid, preferably acetic acid, preferably formic acid.
In one embodiment the composition comprising an acid further comprises a penetration enhancer.
Preferably the penetration enhancer is a terpene or terpenoid, preferably limonene or menthol,
preferably D-limonene or L-menthol, preferably D-limonene. In one embodiment, the skin or hide
is contacted before a) with a composition comprising formic acid and D-limonene, preferably about
0.3% formic acid and about 1% D-limonene based on skin weight. In one embodiment, contacting
with a composition comprising an acid and a penetration enhancer is for about 15 minutes to about
120 minutes, preferably for about 30 minutes to about 90 minutes, preferably for about 45 minutes
to about 75 minutes, preferably for about 60 minutes.
Various embodiments of the method of the first, second, third, fourth, fifth and sixth aspects of the
invention are set out below in the detailed description of the invention, but the invention is not
limited thereto.
Other aspects of the invention may become apparent from the following description which is given
by way of example only and with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described by way of example only and with reference to the drawings in
which:
Figure 1 shows a comparative demonstration of a depilation method according to the invention.
Figure 2 shows the grain surface of an unprotected, conventional lime sulfide depilated ovine skin
after processing to crust leather. Bar = 100µm.
Figure 3 shows the grain surface of an unprotected enzyme depilated ovine skin after processing to
crust leather. Bar = 100µm.
Figure 4 shows the grain surface of a protected conventional lime sulfide depilated ovine skin after
processing to crust leather. Bar = 100µm.
Figure 5 shows the grain surface of a protected enzyme depilated ovine skin after processing to
crust leather. Bar = 100µm.
Figure 6 shows a comparative demonstration of alternative protective agents.
Figure 7 shows a comparative demonstration of alternative depilation enzymes.
Figure 8 shows a comparative demonstration of different reducing agents.
Figure 9 shows the grain surface of a protected enzyme depilated hide skin after processing to crust
leather. Bar = 100µm.
Figure 10 shows the grain surface of a protected enzyme depilated deer skin after processing to
crust leather. Bar = 100µm.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
Unless otherwise specified, all technical and scientific terms used herein are to be understood as
having the same meanings as is understood by one of ordinary skill in the relevant art to which this
disclosure pertains. Examples of definitions of common terms in tanning, and hide and skin
processing can be found in International Council Of Tanners, (1999). International Glossary Of
Leather Terms (2nd Edition). Northampton.
11
It is also believed that general practice of the present invention can be performed using standard
tanning, and skin or hide processing protocols and procedures as known in the art, and as described,
for example in Sharphouse 1971, Bienkiewicz, K., Ed. (1983); Covington, A. (2009)
The following definitions are presented to better define the present invention and as a guide for
those of ordinary skill in the art in the practice of the present invention.
The term "protective agent" as used herein refers to any suitable agent that renders a protein
impervious to enzymatic hydrolysis. In one non limiting embodiment, a "protective agent" is a
molecule that is capable of inducing a chemical bond between proteins. For example, a molecule
useful in the invention that is capable of inducing a chemical bond between proteins may be a
"cross linking agent". Typically the cross linking agent will be a chemical which induces protein
cross links. In one non limiting embodiment, the cross-linking agent is a molecule that is capable of
inducing disulfide bonds between collagen fibrils. In addition, additional protective agents that may
be useful in the invention may be reagents which inhibit enzyme proteolysis but do not induce
cross-links.
The term "activating agent" as used herein refers to an agent that, when contacted to a skin or hide,
will penetrate the skin or hide, preferably fully penetrate the skin or hide, and activate the depilatory
enzyme present in situ in the skin or hide.
The term "deswelling agent" as used herein refers to an agent that will act to reduce the looseness of
a depilated skin or hide when the skin or hide has been processed in a condition of high pH( >9) by
a method of the invention.
The key to enzymatic depilation is the detachment of the dermal epidermal junction and the
subsequent breakdown of the cells of the IRS and the ORS of the hair (Yates, 1968). Accordingly,
the term "depilatory active structures" as used herein refers to the specific structures which attach
12
the epidermis to the dermis and the substance of the outer root sheath (ORS) and the inner root
sheath (IRS).
Quantities given as wt/wt herein refer to the given weight of an additive based on the given weight
of a skin or hide material to be treated. For example 1% Na2S (gNa2S/gSkin material) refers to 1g
Na2S per 100g Skin material.
The term "g/Skin material" as used herein refers to the weight in grams of a "green fleshed skin" or
"green fleshed hide" as known and used in the art. For example, a green fleshed sheep skin is a
freshly flayed sheep skin that has had adhering flesh and fat scraped from the flesh side and has not
been salted or pickled.
The term "based on skin weight" refers to the weight of a "green fleshed skin" or "green fleshed
hide" as described above.
The term "acidic" as used herein with reference to a pH range refers to a pH of about 1.0 to about
6.5.
The term "neutral" as used herein with reference to a pH range refers to a pH of about 6.6 to about 8.
The term "alkaline" as used herein with reference to a pH range refers to a pH of about 8.1 to about
14.
The term "ultra low amount(s) of sodium sulfide" as used herein refers to a concentration of sodium
sulfide that would be considered in the art to be too low for successful unhairing. For example,
below about 40g/m² (60% active sodium sulfide flake per square meter of hide or skin) or below a
concentration in the drum of 1.2% sodium sulfide (Na2S), but not limited thereto.
The term "alkaline protease" (AP), as used herein refers to an enzyme or enzyme mix comprising a
broad spectrum of endopeptidase activity active in the alkaline pH range (8-14)
13
The term "sugar reagent" as used herein refers to a sugar that will react with calcium hydroxide to
form calcium sucrate or an analogous calcium sugar salt. Examples of sugar reagents include, but
are not limited to, monosaccharides such as glucose, glyceraldehyde and galactose, disaccharides
such as sucrose, lactose and maltose, and other sugars. What is important is that the "sugar reagent"
has the ability to react with calcium hydroxide to form calcium sucrate under the conditions
specified in the method.
The term "neutralizing agent" as used herein refers to any agent that will neutralize the pH in and/or
on the skin or hide after treatment of the skin or hide with the neutralizing agent. Preferably the
neutralizing agent will reduce the alkalinity on and/or in the skin or hide, but not limited there to.
For example, a neutralizing agent may, in some embodiments neutralize acidity.
The term "an agent that reduces the free alkalinity" refers to any agent or process that will reduce
free alkalinity. Preferably an agent that reduces the free alkalinity of a processing bath reduces the
concentration of free alkaline salts to less than about <1% wt/wt.
The term "substantially inactive" as used herein with reference to enzyme activity refers to the
activity of the enzyme which will, at the given pH, have either no activity or only residual activity
such that any residual activity will have no material effect on the skin or hide. For an
endopeptidase or alkaline protease used according to the invention this means that "an enzyme that
is substantially inactive" or an enzyme that is in a "substantially inactive state" is an enzyme that
will have no peptidase or protease activity or only residual peptidase or protease activity at the
given pH such that any peptidase or protease activity of the enzyme will have no material effect on
the skin or hide. For example, a "substantially inactive enzyme" or an enzyme in a "substantially
inactive state" as used herein refers to an enzyme that shows less than about 1% of its normal
activity at the tested pH when compared to its normal activity at its optimal pH.
The term "deliming" as used herein refers to deliming processes as known in the art that are carried
14
out on a skin or hide for completely neutralizing the residual alkali present in a skin or hide
following an alkaline depilation, that allow tanning to properly proceed (Harris D. (Ed.) Dictionary
of the terms used in the hides, skins, and leather trade. 1974 Washington D.C.: US department of
Agriculture.)
The term "pickling" as used herein refers to pickling processes as known in the art that are carried
out on an unhaired or depilated skin or hide to reduce the pH of the unhaired or depilated skin or
hide to below pH 3.0 in the presence of ample salt. Normally 3% salt is based on the total weight of
water used in the pickling process (Harris, D. 1974 Supra)
The term "processed into leather" as used herein refers to skin or hide material which has been
tanned to as to be imputrescible, impervious to and insoluble in water (Harris, D. 1974 Supra).
The term "wet blue" as used herein refers to leather, which after the chrome tanning process has not
been further processed and is sold in the wet state (International Council Of Tanners, 1999).
The term "degreased" as used herein refers to hides or skins which have been treated to remove a
substantial proportion of the natural fats present in the skin <1% wt/wt (dry matter basis) (Harris, D.,
1974).
"NOVOLIME®" is a proprietary enzyme composition comprising subtilisin and lipase.
The term “comprising” as used in this specification and claims means “consisting at least in part
of”. When interpreting statements in this specification, and claims which include the term
“comprising”, it is to be understood that other features that are additional to the features prefaced by
this term in each statement or claim may also be present. Related terms such as “comprise” and
“comprised” are to be interpreted in similar manner.
Description
The present invention relates generally to an enzymatic process for removing wool or hair from
hides or skins using enzymes. The inventor has determined that the process described herein can be
carried out in the absence of sodium sulfide, or in the presence of ultra low amounts of sodium
sulfide, to produce skins or hides having minimal to no grain damage. Skins or hides produced by
the inventive methods disclosed herein have a higher grain quality as compared to skins or hides
processed by other-enzyme based depilation methods.
The inventor believes that they are the first to show that the pre-treatment of raw skins or hides with
a protective agent comprising a THP compound, particularly a tetrakis (hydroxymethyl)
phosphonium salt, particularly tetrakis (hydroxymethyl) phosphonium sulfate (THPS), acts to fully
protect the skin or hide from degradation during a subsequent enzyme based depilation process. In
particular, the inventor has shown that without the use of a protective agent before enzymatic
depilation, a skin or hide that is processed by standard enzymatic depilation as may be known in the
art, is badly damaged by the enzyme, thereby greatly reducing the quality of the leather produced
from such a skin or hide.
In the inventive process disclosed herein, a depilatory enzyme in an inactive or substantially
inactive state is applied to the skin or hide that has been pre-treated with a protective agent. The
enzyme is then activated in situ in the skin or hide. The inventor has determined that the pretreatment of the skin or hide with the protective agent followed by in situ activation of an alkaline
active depilation enzyme is particular effective at producing skins or hides of superior quality for
further processing.
In the method described herein the protective agent is applied to the raw skin or hide and allowed to
fully penetrate the skin or hide such that the full thickness of the skin or hide contains the protective
agent. An alkaline active enzyme is then applied to the pre-treated skin or hide at a neutral pH and
allowed to penetrate the skin or hide to reach the region of depilatory activity around the follicle
16
root. The enzyme is then activated in situ using an activating composition applied to the skin or
hide. Preferably the activating composition is applied to the flesh side of the skin or hide. The
activating composition may be in the form of an activating paint, but is not limited there to. The
activating composition also contains a small amount of lime (hydrated calcium oxide), a reducing
agent to ensure complete depilation of the skin or hide and a deswelling agent. The activating
composition may contain a penetration enhancer that enhances penetration of the constituents of the
activating composition into the skin or hide.
Surprisingly, the inventor has found that a skin or hide of superior quality may be produced when
the process described herein employs as a protective agent, a cross linking agent that is capable of
inducing disulfide bonds between collagen fibrils. Particularly effective cross-linking agents
include tetrakis(hydroxymethyl)phosphine compounds (THP),
tetrakis(hydroxymethyl)phosphonium salts (THP salts), tetrakis(hydroxymethyl)phosphine
condensates (THP condensates), and oxazolidine. Preferably the THP salt is
tetrakis(hydroxymethyl)phosphonium salt. Preferably, the tetrakis(hydroxymethyl)phosphonium
salt is a sulfate, chloride, phosphate, nitrate, bromide, or fluoride salt. Preferably the THP salt is
tetrakis(hydroxymethyl)phosphonium sulfate (THPS) or tetrakis(hydroxymethyl)phosphonium
chloride (THPC), although the invention is not limited thereto. Preferably, the THP salt is
tetrakis(hydroxymethyl)phosphonium sulfate (THPS).
In one embodiment, the method of the invention comprises an initial step of acidifying the raw skin
or hide before contacting with a protective agent or cross-linking agent according to the methods
described herein. Without wishing to be bound by theory, the inventor believes that acidification of
the skin or hide before treatment with a protective agent or protein crosslinking agent as described
herein may allow the protective agent or protein crosslinking agent to achieve better penetration of
the skin or hide according to a method of the invention, allowing for a more "even" or less
"astringent" tanning reaction. Leather produced from a skin or hide treated as described has less
17
"draw". Accordingly, in various embodiments, a method of the invention comprises, before
contacting the skin or hide with a protective agent or a protein crosslinking agent, acidifying the
skin or hide by contacting the skin or hide with a composition comprising an acid. In some
embodiments the composition comprising the acid further comprises a penetration enhancer.
Preferably the acid is an organic acid, preferably a carboxylic acid, preferably acetic acid,
preferably formic acid, and the penetration enhancer is a terpene or terpenoid, preferably limonene
or menthol, preferably D-limonene or L-menthol, preferably D-limonene.
The applicant believes that they are the first to successfully demonstrate that following a method of
the invention of pre-protecting a raw skin or hide before enzyme based depilation, provides a
depilated skin or hide of superior quality for further processing.
Accordingly, in one aspect the invention relates to a method for removing wool or hair from at least
one raw skin or hide, the skin or hide having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with a composition comprising a protective agent,
b) contacting the washed skin or hide with a composition comprising a depilatory enzyme that
is active at an alkaline pH greater than about 8,
c) contacting the skin or hide with an activating composition comprising a base and a
deswelling agent, wherein the base activates the depilatory enzyme in b) to act on the
depilatory active structures in the skin or hide, and
d) removing the wool or hair from the skin or hide.
In one embodiment the method further comprises
e) neutralizing the base on and/or in the skin or hide.
18
In one embodiment the method comprises
f) washing the skin or hide with water between step a) and step b).
In one embodiment the water further comprises an additional reagent.
In one embodiment of the method, removing the wool or hair from the skin or hide is carried out
after contacting the skin or hide with the neutralizing agent. In one embodiment removing the wool
or hair comprises pulling, but is not limited thereto. It is believed that various ways of removing
the wool or hair can be employed in the method of the invention and that such ways are known to a
person of skill in the art (Covington A.D. 2009).
In one embodiment the method further comprises
g) removing a neutralizing agent that has been used to neutralize the base on and/or in the skin
or hide.
In one embodiment the method further comprises
h) washing the skin or hide in water after g).
In one embodiment the water in h) comprises an additional reagent.
In one embodiment the method further comprises the step of
i) processing the skin or hide using conventional deliming and then pickling techniques to
produce a pickled skin or pickled hide.
In one embodiment the method comprises
j) as an alternative to (i) the steps of degreasing the skin or hide followed by processing the
skin or hide directly to wet blue without a pickling step.
19
In one embodiment the method further comprises
k) processing the pickled or wet blue skin or hide into leather.
It is believed that contacting the skin or hide according to the method of the invention can be carried
out by the person of skill in the art according to standard methodology in the art, and as described
herein (e.g., Carrie, 1960, supra).
In one embodiment the method comprises an initial acidification of the raw skin or hide before a)
by contacting the skin or hide with a composition comprising an acid. In one embodiment the
composition comprising an acid comprises about 0.01% to about 1% acid based on skin weight,
preferably about 0.1% to about 0.5% acid based on skin weight, preferably at about 0.3% acid
based on skin weight. Preferably the acid is an organic acid, preferably a carboxylic acid,
preferably acetic acid, preferably formic acid. Other suitable acids are contemplated herein, the use
of which will be readily apparent to the skilled worker.
In one embodiment, the composition comprising an acid further comprises a penetration enhancer.
Preferably the penetration enhancer in the composition comprising an acid is a terpene or terpenoid,
preferably limonene or menthol, preferably D-limonene or L-menthol, preferably D-limonene. In
one embodiment the penetration enhancer is present at a concentration of about 0.1% to about 5%,
preferably about 0.5% to about 3%, preferably about 0.75% to about 2%, preferably about 1%
based on skin weight. Preferably the penetration enhancer is D-limonene and is present at a
concentration of about 1% based on skin weight.
In one embodiment, the initial acidification of the skin or hide comprises contacting with the skin or
hide with the composition comprising an acid or the composition comprising an acid and a
penetration enhancer, for about 1 minute to about 120 minutes, preferably for about 10 minutes to
about 90 minutes, preferably for about 30 minutes to about 75 minutes, preferably for about 60
minutes.
In one embodiment, the contacting in a) is carried out by adding the protective agent to the
composition comprising the acid or the composition comprising the acid and the penetration
enhancer.
In one embodiment contacting the skin or hide with the composition in a) is contacting in a
processing bath. Preferably the processing bath is comprised in a processing paddle, processing
drum, or challenge cook processor, but not limited thereto. Preferably the skin or hide is wholly or
partially immersed in the processing bath. Preferably the skin or hide is wholly immersed in the
processing bath.
In one embodiment the contacting in a) is contacting by painting as known in the art. For example,
paint application to skins is well described in the art (Carrie et al. 1960).
In one embodiment the composition in a) is an aqueous solution that comprises the protective agent.
In one embodiment the protective agent is a cross linking agent that cross-links collagen fibrils.
In one embodiment the contacting in a) is for a time sufficient to allow the protective agent to fully
penetrate the hide or skin. Preferably the full thickness of the hide or skin should contain the
protective agent. Preferably the full thickness of the hide or skin contains a protective agent that is
a cross linking agent that has reacted with the collagen in the skin or hide.
In one embodiment the contacting in a) is from about 2 to about 16 hours, preferably from about 2.5
to about 8 hours, preferably about 3 to about 4 hours, preferably about 3 hours.
In one embodiment the protective agent is a cross linking agent that is a THP compound, THP salt
or THP condensate. Preferably the THP salt is selected from the group consisting of a tetrakis
21
(hydroxymethyl) phosphonium salt of the formula THP"X" where "X" is an anion selected from the
group consisting of sulfate, chloride, phosphate, bromide, nitrate, and fluoride. Preferably the anion
is sulfate or chloride, preferably the compound is tetrakis (hydroxymethyl) phosphonium sulfate
(THPS).
In one embodiment the cross linking agent is a THP compound, THP salt or THP condensate or
oxazolidine and is present in a) at a concentration of about 0.25% to about 20%, preferably about
0.5% to about 15%, preferably about 0.75 to about 10%, preferably about 1% to about 5%,
preferably about 1.5% to about 3%, preferably about 2% wt/wt (gTHP, gTHP salt or gTHP
condensate/gSkin material). Preferably the cross-linking agent is a THP salt selected from the
group consisting of a tetrakis (hydroxymethyl) phosphonium salt of the formula THP"X" where "X"
is an anion selected from the group consisting of sulfate, chloride, phosphate, bromide, nitrate, and
fluoride. Preferably the anion is sulfate or chloride, preferably the compound is tetrakis
(hydroxymethyl) phosphonium sulfate (THPS).
In one embodiment the washing between a) and b) comprises washing with 300% w/vol of water.
In one embodiment the washing between a) and b) comprises washing the skin or hide in a
processing bath that comprises water. Preferably the processing bath is comprised in a processing
drum. Preferably the skin or hide is wholly or partially immersed in the processing bath.
Preferably the skin or hide is wholly immersed in the processing bath.
In one embodiment the washing between a) and b) results in the removal of substantially all the unreacted protective agent from the skin or hide.
In one embodiment, the composition in b) optionally comprises a deswelling agent.
In one embodiment the contacting in b) is comprises contacting the skin or hide in a processing bath
that comprises a depilatory enzyme in an aqueous solution. Preferably the processing bath is
22
comprised in a processing drum. Preferably the skin or hide is wholly or partially immersed in the
processing bath. Preferably the skin or hide is wholly immersed in the processing bath.
In one embodiment the contacting in b) is carried out by painting or spraying the flesh side of the
skin or hide with an aqueous solution comprising a depilatory enzyme, or by at least partially
immersing the skin or hide in an aqueous solution comprising a depilatory enzyme. Preferably the
contacting in b) is carried out by at least partially immersing the skin or hide in the aqueous
solution.
In one embodiment the contacting in b) is carried out at an acidic or neutral pH.
In one embodiment the contacting in b) is carried out at a pH of at least 4 to about 8. Preferably the
pH is at least 5 to about 8. Preferably the pH is about 6 to about 8. Preferably the pH is about 6.5
to 7.5. Preferably the pH is about 7.
In one embodiment the contacting in b) is carried out in the absence of sodium sulfide.
In one embodiment the contacting in b) is carried out in the presence of ultra low amounts of
sodium sulfide. Preferably an ultra low amount of sodium sulfide is an amount of sulfide that is
normally considered in the art to be too low for successful unhairing. Preferably the contacting in
b) is carried out with sodium sulfide concentration of less than about 40g/m² (60% active sodium
sulfide flake per square meter of hide or skin) or below a concentration in the drum of 1.2% sodium
sulfide (Na2S).
In one embodiment the ultra low amount of sodium sulfide is sulfide at a concentration of less than
about 1%, preferably about 0.05 to about 0.95%, preferably about 0.1 to about 0.8%, preferably
about 0.1 to about 0.7%, preferably about 0.7% wt/wt (gNa2S/gSkin material).
23
In one embodiment the enzyme in b) is an enzyme having a broad spectrum of endopeptidase
activity at an alkaline pH.
In one embodiment the enzyme in b) is an alkaline protease that comprises a broad spectrum
endopeptidase activity. Preferably the alkaline protease is selected from the group consisting of an
animal alkaline protease, plant alkaline protease or microbial alkaline protease. Preferably the
alkaline protease is an alkaline serine protease. Preferably the alkaline protease is a microbial
alkaline protease, preferably subtilisin, but not limited thereto.
In one embodiment the enzyme is present in b) at a concentration of about 0.25% to about 6%,
preferably about 0.5% to about 5%, preferably about 0.75% to about 4%, preferably about 1% to
about 3%, preferably about 2% or about 3% wt/vol of an enzyme with an activity of 0.5AU/min as
assessed by the method of Mozersky and Bailey 1992. In one embodiment the enzyme is added in a
volume float.
In one embodiment the composition in b) optionally further comprises at least one additional
enzyme. Preferably the at least one additional enzyme is a lipase.
In one embodiment the composition in b) further comprises a penetration enhancer. Preferably the
penetration enhancer is a terpene or terpenoid, preferably limonene or menthol, preferably Dlimonene or L-menthol, preferably D-limonene. Without wishing to be bound by theory, the
inventor believes that the addition of a penetration enhancer to the composition in b), particularly
limonene or menthol, is a possible means to improve the quality of the depilation of the skin or
hide.
In one embodiment the contacting in b) is for a time sufficient to allow the enzyme or enzymes in
the solution to penetrate into the skin or hide. Preferably the contacting in b) is for a time sufficient
to allow the enzyme to reach the region of depilatory activity around the follicle root. Preferably
24
penetration of the enzyme or enzymes is penetration of the enzyme or enzymes into the wool or hair
follicle of the skin or hide.
In one embodiment contacting in b) is contacting for about 1 hour to about 20 hours, preferably
about 1-16 hours, preferably about 1-12 hours, preferably about 1-8 hours, preferably about 2 to 4
hours, preferably about 2 hours.
In some embodiments the method comprises an additional step of removing excess composition
contacted to the skin or hide in b) before contacting the skin or hide with the activating composition
in c).
In one embodiment contacting the skin or hide with the activating composition in c) is for a time
sufficient to activate the enzyme present on and/or in the skin or hide after contacting in b).
In one embodiment contacting with the activating composition in c) is for a sufficient time to allow
the base comprised in the activating composition to raise the pH from an acidic or neutral pH to an
alkaline pH and to allow the enzyme to act on the depilatory active structures in the skin or hide.
Preferably the time sufficient to allow the base to raise the pH from an acidic or neutral pH to an
alkaline pH and to allow the enzyme to act on the depilatory active structures in the skin or hide is
from about 10 minutes to about 24 hours, preferably about 15 minutes to about 22 hours, preferably
about 20 minutes to about 20 hours, preferably about 30 minutes to about 18 hours, preferably about
1 hour to about 17 hours, preferably about 2 hours to about 16 hours, preferably about 16 hours.
In one embodiment the pH is raised from a pH of about 4 to about 6, or from a pH of about 6 to
about 8, to a pH of about 9 to about 12, preferably from a pH of about 5 to about 7 to a pH of about
.5 to greater than about 13, preferably to a pH of at least about 13.
In one embodiment the pH is raised to a pH of a least 13 in the presence of about 8% to about 14%
NaOH (wt/vol), preferably about 10% NaOH (wt/vol) to about 13% NaOH (wt/vol), preferably
about 12.5% NaOH (wt/vol).
In one embodiment contacting with the activating composition in c) comprises direct application of
the composition to the flesh side of the skin or hide. Preferably direct application is by a direct
application selected from a group consisting of partially immersing, pouring, painting or spraying or
a combination thereof. Preferably direct application is by spray coat or curtain coat.
In one embodiment the base in the activating composition in c) is provided at a concentration
sufficient to activate the enzyme in the skin or hide.
In one embodiment the base is selected from the group consisting of calcium hydroxide and sodium
hydroxide. Preferably the base is a combination of calcium hydroxide and sodium hydroxide, but is
not limited thereto.
In one embodiment the base in the activating composition in c) is present at a concentration of
about 1% to about 40%, preferably at about 3% to about 35%, preferably at about 7% to about 30%,
preferably at about 7% to about 25%, preferably at about 8% to about 20%, preferably at about 9%
to about 15%, preferably at about 10% (w/vol).
In one embodiment the base is a combination of calcium hydroxide and sodium hydroxide wherein
the calcium hydroxide is present at a concentration of about 4% to about 6%, preferably about 5%
and the sodium hydroxide is present at a concentration of about 15% to about 25%, preferably about
% wt/vol.
In one embodiment the deswelling agent present in the activating composition in c) acts to repress
the swelling of the skin or hide at an alkaline pH. Preferably the deswelling agent is a sodium salt
26
that acts to repress the swelling of the skin or hide at alkaline pH. Preferably the sodium salt is
sodium sulfate.
In one embodiment the deswelling agent is present in the activating composition in c) at a
concentration of about 0.1% to about 10%, preferably about 0.3% to about 9%, preferably about
0.5% to about 8%, preferably about 0.75% to about 7%, preferably about 0.1% to about 6%,
preferably at about 5% w/vol.
In one embodiment the contacting in c) further comprises contacting the skin or hide with a further
agent that assists in depilation. Preferably the further agent provides a source of calcium ions,
preferably the further agent is a calcium salt. Preferably the further agent is hydrated calcium oxide.
In one embodiment the further agent is present in the activating composition in c). Preferably the
further agent is present in the activating composition at a concentration of about 1% to about 10%,
preferably about 2% to about 8%, preferably at about 3% to about 6%, preferably at about 5%
w/vol.
In one embodiment the contacting in c) further comprises contacting the skin or hide with a
reducing agent. In one embodiment the reducing agent is present in the activating composition in c).
In one embodiment the reducing agent is a sulfur-based organic reducing agent. Preferably the
sulfur based organic reducing agent comprises a thiol group. Preferably the sulfur based organic
reducing agent is selected from the group consisting of sodium thioglycolate, thioglycolic acid, and
2-mercaptoethanol. Preferably the reducing agent is thioglycolic acid.
In one embodiment the reducing agent in the activating composition in c) is present at a
concentration of about 1% to about 6%, preferably at about 2% to about 4%, preferably at about 3%
w/vol, preferably at about 1% w/vol.
27
In one embodiment the reducing agent is present in a molar concentration that is equivalent to the
molar concentration of 0.7% wt/wt sodium sulfide.
In one embodiment the activating composition in c) is an aqueous solution comprising about 5%
hydrated calcium oxide, about 3% thioglycollic acid, about 5% sodium sulfate and about 10%
sodium hydroxide wt/vol.
In one embodiment the activating composition in c) is an aqueous solution comprising about 1%
hydrated calcium oxide, about 1% sodium thioglycolate, about 5% sodium sulfate and about 12.5%
sodium hydroxide wt/vol. Preferably the activating composition in c) comprises no sodium sulfide.
In one embodiment the neutralizing in e) comprises processing the skin or hide to reduce the pH on
and/or in the skin or hide to an acidic or neutral pH. In one embodiment the process removes a
sufficient amount of the base on and/or in the skin or hide to reduce the pH on and/or in the skin or
hide to a pH of about 9 to about 12, preferably of about 10 to about 11, preferably of about 10.5.
In one embodiment the neutralizing in e) comprises contacting the skin or hide with a neutralizing
agent that neutralizes the free alkali to a pH of 10.5.
In one embodiment the neutralizing agent is comprised in an aqueous neutralizing solution.
In one embodiment neutralizing in e) comprises contacting the skin or hide with a neutralizing
agent for a time sufficient to neutralize at least some of the free alkali present in and/or on the skin
or hide. In one embodiment, contacting the skin or hide is for a time sufficient to neutralize all, or
substantially all, of the free alkali in and/or on the skin or hide.
In one embodiment contacting for a time sufficient to neutralize at least some, substantially all, or
all, of the base is from about 10 minutes to about 12 hours, preferably about 20 minutes to about 10
28
hours, preferably about 25 minutes to about 8 hours, preferably about 30 minutes to about 4 hours,
preferably about 30 minutes to about 1 hour, preferably about 30 minutes.
In one embodiment neutralizing the skin or hide in e) comprises contacting the skin or hide with the
neutralizing agent in a processing bath that comprises the neutralizing agent in an aqueous solution.
Preferably the skin or hide is wholly or partially immersed in the processing bath. Preferably the
skin or hide is wholly immersed in the processing bath. Preferably the processing bath is comprised
in a processing drum.
In another embodiment neutralizing the skin or hide in e) comprises directly applying a neutralizing
agent to the flesh side of the skin or hide. Preferably directly applying the neutralizing agent is by a
direct application selected from a group consisting of pouring, painting or spraying or a
combination thereof. Preferably direct application is by roller, sponge or brush or by a combination
thereof.
In one embodiment the neutralizing agent comprises a sugar reagent that reacts with free calcium
hydroxide, preferably to form calcium sucrate, and an agent that reduces the free alkalinity of the
processing bath.
In one embodiment the sugar reagent is a monosaccharide or a disaccharide. Preferably the sugar
reagent is selected from the group consisting glucose, glyceraldehyde, galactose, sucrose, lactose
and maltose. Preferably the sugar reagent is sucrose.
In one embodiment the sugar is present in the neutralizing agent at a concentration of about 0.1% to
about 8%, preferably about 1% to about 7%, preferably about 2% to about 6%, preferably about 3%
to about 6%, preferably about 4% to about 5%, preferably about 5%.
In one embodiment the agent that reduces the free alkalinity in the processing bath is present in the
neutralizing agent at a concentration of 6-14% w/vol. Preferably the concentration of the agent that
29
reduces the free alkalinity in the processing bath is 10% wt/vol. Preferably the agent that reduces
the free alkalinity in the processing bath is ammonium chloride or calcium chloride, preferably
calcium chloride.
In one embodiment the neutralizing agent further comprises a deswelling agent, preferably the
deswelling agent is a sodium salt, preferably sodium sulfate.
In one embodiment the deswelling agent is present in the neutralizing agent in e) at a concentration
of about 0.25% to about 6%, preferably at about 0.5% to about 5%, preferably at about 0.75% to
about 4%, preferably at about 1% to about 3%, preferably at about 2%. In one embodiment the
deswelling agent is sodium sulfate and is present at a concentration of about 1% to about 6%,
preferably at about 5%, preferably at about 4%, preferably at about 3%, preferably at about 2%.
In one embodiment the neutralizing agent is removed from the skin or hide by washing. Removal
of the neutralizing agent by washing may be carried out by a person of skill in the art according to
standard procedures known and used in the art (Covington A.D. Supra; Sharpehouse J.H., Supra).
In one embodiment the neutralizing agent is removed from the skin or hide by washing in water
from about 1 to about 10 times, preferably about 2-9 times, preferably about 3-8 times, preferably
about 3- 5 times, preferably about 3-4 times, preferably about 3 times.
In a second aspect the invention relates to a method for removing wool or hair from at least one raw
skin or hide, the skin or hide each having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with an aqueous solution comprising a tetrakis (hydroxymethyl)
phosphine (THP) compound, a tetrakis (hydroxymethyl) phosphonium salt (a THP salt), a
THP condensate or oxazolidine,
b) contacting the skin or hide with an aqueous solution comprising an alkaline serine protease
in a substantially inactive state,
c) contacting the skin or hide with an activating composition comprising hydrated calcium
oxide, thioglycolic acid, sodium sulfate and sodium hydroxide to activate the enzyme in b),
and
d) removing the wool or hair from the skin or hide.
In one embodiment the method further comprises
e) contacting the skin or hide with a neutralizing agent comprising sucrose and calcium
chloride to neutralize the pH on and/or in the skin or hide.
In one embodiment the method comprises
a) washing the skin or hide with water between step a) and step b).
In one embodiment the contacting in c) is contacting the flesh side of the skin or hide with the
activating composition.
In one embodiment the method of the second aspect comprises an initial acidification of the skin or
hide before a) as described in detail above for the first aspect of the invention.
In one embodiment of the method of the second aspect, the contacting in a) is carried out by adding
a tetrakis (hydroxymethyl) phosphine (THP) compound, a tetrakis (hydroxymethyl) phosphonium
salt (a THP salt), a THP condensate or oxazolidine to the composition comprising the acid or the
composition comprising the acid and the penetration enhancer.
In a third aspect the invention relates to a method for removing wool or hair from at least one raw
skin or hide, the skin or hide each having a flesh side and a grain side, the method comprising
31
a) contacting the skin or hide with a composition comprising a protein cross-linking agent,
b) contacting the skin or hide with a composition comprising a depilatory enzyme that is
substantially inactive at the pH of the composition,
c) contacting the skin or hide with an activating composition comprising an agent that activates
the depilatory enzyme in b), and a deswelling agent, and
d) removing the wool or hair from the skin or hide.
In one embodiment the method comprises
e) washing the skin or hide with water between step a) and step b).
In one embodiment of the third aspect, the activating agent comprises a base in a concentration
sufficient to activate the depilatory enzyme.
In one embodiment of the third aspect, the enzyme is a broad spectrum endopeptidase, preferably an
alkaline serine protease, preferably subtilisin.
In one embodiment of the third aspect the method further comprises
b) neutralizing the base on and/or in the skin or hide.
In one embodiment of the third aspect, the conditions that maintain the enzyme in a substantially
inactive state are conditions of acidic or neutral pH on and/or inside the skin or hide. Preferably the
conditions are neutral pH on and/or in the skin or hide.
In one embodiment of the third aspect, the contacting in c) is contacting the flesh side of the skin or
hide with the activating composition.
32
In one embodiment the method of the third aspect comprises an initial acidification of the skin or
hide before a) as described in detail above for the first aspect of the invention.
In one embodiment of the method of the third aspect, the contacting in a) is carried out by adding
protein cross-linking agent to the composition comprising the acid or the composition comprising
the acid and the penetration enhancer.
In a fourth aspect the invention relates to a method for removing wool or hair from at least one skin
or hide, the skin or hide each having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with a composition comprising a protein cross-linking agent,
b) contacting the skin or hide with a composition comprising a depilatory enzyme under
conditions that maintain the enzyme in a substantially inactive state,
c) contacting the flesh side of the skin or hide with an activating composition comprising an
activating agent to activate the depilatory enzyme in b), and
d) removing the wool or hair from the skin or hide.
In one embodiment the method comprises
e) washing the skin or hide with water between step a) and step b).
In one embodiment of the fourth aspect the activating composition in c) comprises a deswelling
agent.
In one embodiment of the fourth aspect the activating agent comprises a base in a concentration
sufficient to raise the pH on and/or in the hide to an alkaline pH.
In one embodiment of the fourth aspect, the enzyme is a broad spectrum endopeptidase, preferably
an alkaline serine protease, preferably subtilisin.
33
In one embodiment the method of the fourth aspect comprises an initial acidification of the skin or
hide before a) as described in detail above for the first aspect of the invention.
In one embodiment of the method of the fourth aspect, the contacting in a) is carried out by adding a
protein cross-linking agent to the composition comprising the acid or the composition comprising
the acid and the penetration enhancer.
In a fifth aspect the invention relates to a method for removing wool or hair from at least one raw
skin or hide, the skin or hide having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with an composition comprising a protective agent,
b) contacting the skin or hide with a composition comprising a depilatory enzyme that is active
at an alkaline pH,
c) contacting the flesh side of the skin or hide with an activating composition comprising a
base and a deswelling agent, wherein the base activates the depilatory enzyme in b) to act on
the depilatory active structures in the skin or hide, and
d) removing the wool or hair from the skin or hide,
wherein the method either i) does not use a sulfide, or ii), uses sodium sulfide at concentrations of
less than about 1% Na2S (gNa2S/gSkin material).
In one embodiment the further comprises
e) washing the skin or hide with water between step a) and step b).
In one embodiment of the fifth aspect, ii) uses sodium sulfide at a concentration of about 0.5 to
about 0.9% gNa2S/gSkin material, preferably about 0.7% gNa2S/gSkin material.
34
In one embodiment the method of any of the first through fourth aspects either i) does not use
sulfide or ii) uses sodium sulfide at a concentration of less than about 1% Na2S (gNa2S/gSkin
material).
In one embodiment the method of the fifth aspect comprises an initial acidification of the skin or
hide before a) as described in detail above for the first aspect of the invention.
In one embodiment of the method of the fifth aspect, the contacting in a) is carried out by adding a
protective agent to the composition comprising the acid or the composition comprising the acid and
the penetration enhancer.
In a sixth aspect the invention relates to a method for removing wool or hair from at least one raw
skin or hide, the skin or hide having a flesh side and a grain side, the method comprising
a) contacting the skin or hide with a composition comprising about 2% tetrakis
(hydroxymethyl) phosphonium sulfate (THPS) (wtTHPS/wtSkin material) for about three
hours,
b) contacting the skin or hide for about 2 hours with a composition comprising about 2%
wt/vol of a depilatory enzyme subtilisin having an activity of 0.5AU/min, the composition
having a pH of about 7,
c) contacting the skin or hide for about 2 to about 16 hours with an activating composition
comprising about 5% hydrated calcium oxide (wt/vol), about 3% thioglycollic acid (wt/vol),
about 0.5% sodium sulfate (wt/vol) and about 10% sodium hydroxide (wt/vol) to activate
the subtilisin, and
d) removing the wool or hair from the skin or hide.
In one embodiment of the method of the sixth aspect, the composition in b) comprises about 3%
wt/vol of a depilatory enzyme subtilisin having an activity of 0.5AU/min, the composition having a
pH of about 7.
In one embodiment of the method of the sixth aspect, the activating composition in c) comprises
about 1% hydrated calcium oxide (wt/vol), about 1% sodium thioglycolate (wt/vol), about 0.5%
sodium sulfate (wt/vol) and about 12.5% sodium hydroxide (wt/vol).
In one embodiment the method of the sixth aspect further comprises the step of neutralizing the
base on and/or in the skin or hide by contacting the skin or hide for about 2 hours with a
neutralizing agent comprising sucrose and calcium chloride.
In one embodiment the method of the sixth aspect further comprises the step of removing a
neutralizing agent that has been used to neutralize the base on and/or in the skin or hide.
In one embodiment the method of the sixth aspect further comprises the step of washing the skin or
hide in water between steps a) and b) or after step g) or both.
In one embodiment the method of the sixth aspect further comprises the step of processing the skin
or hide using conventional deliming and then pickling techniques to produce pickled skin or pickled
hide.
In one alternative embodiment the method of the sixth aspect comprises the step of degreasing the
skin or hide followed by processing the skin or hide directly to wet blue without a pickling step.
In one embodiment the method of the sixth aspect further comprises the step of processing the
pickled or wet blue skin or hide into leather.
In one embodiment the method of the sixth aspect either i) does not use sulfide or ii) uses sodium
sulfide at a concentration of about 0.7% (gNa2S/gSkin material).
36
In one embodiment the method of the sixth aspect either i) does not use sulfide or ii) uses sodium
sulfide at a concentration of about 0.7% (gNa2S/gSkin material) or less.
In one embodiment the method of the sixth aspect comprises an initial acidification of the skin or
hide before a) as described in detail above for the first aspect of the invention.
In one embodiment the method of the sixth aspect comprises an initial acidification before a) as
described above, wherein the initial acidification is carried out using a composition comprising
about 0.3% acid and about 1% penetration enhancer based on skin weight. Preferably the initial
acidification is carried out for about 30 to about 90 minutes, preferably for about 60 minutes.
Preferably the acid is formic acid. Preferably the penetration enhancer is D-limonene.
In one embodiment of the method, following an initial acidification as described above, the
contacting in a) is carried out by adding tetrakis (hydroxymethyl) phosphonium sulfate (THPS) to a
concentration of about 2% (wtTHPS/wtSkin material) into the composition comprising the formic
acid and the D-limonene, the concentration of enzyme in b) is about 3%, and the activating
composition in c) comprises about 1% hydrated calcium oxide (wt/vol), about 1% sodium
thioglycolate (wt/vol), about 0.5% sodium sulfate (wt/vol) and about 12.5% sodium hydroxide
(wt/vol).
Following depilation according to a method of the invention, the depilated skin or hide can be
processed to good quality leather by the person of skill in the art following standard methods as
known and used in the art of fellmongering and tanning (Carrie et al. 1960, Supra; Sharphouse
1971, Supra; Covington 2009; Supra).
The invention will now be described by way of the following representative methods and examples
which are provided to further illustrate the subject matter to which the invention relates. The use of
any and all examples, or exemplary language (e.g., "such as" or “including”) provided herein, is
37
intended solely for the purposes of better describing the invention. The presence of examples and
the use of exemplary language does not limit the scope of the invention as disclosed herein unless
specifically otherwise indicated. No language used in the entirety of the disclosure of this
application should be interpreted as indicating that any particular element or feature pertaining to
the invention and as disclosed herein is essential to the practice of the invention, unless explicitly
stated. For example, the skilled worker will be able to modify the quantities of reagents and
processing times in the methods and processes as exemplified, as known in the art, according to the
inventive concepts disclosed herein. Such modifications are considered to be within the scope of
the present invention. Moreover the skilled worker will appreciate, when considering the entirety of
the description of the invention described herein, that the various embodiments and preferences set
out for various different aspects of the invention may be used together with various other
embodiments and preferences, and in various other aspects of the invention to carry out a method of
the invention as contemplated herein.
EXAMPLES
General Experimental Protocols
Example 1
Enzyme depilation of green sheep skins to produce a pickled skin
In the following example all processing steps were carried out at 25°C.
Pre-treatment with the protective agent
A pre-fleshed sheep skin was initially processed in a processing drum containing two volumes of
water (200% of skin weight) and 2% protective agent, tetrakis hydroxyphosphonium sulfate (THPS)
38
(% wt/vol in solution). The skin was agitated by rotation for 3 hours at 5 rpm, allowing the
protective agent to fully penetrate the raw skin.
After penetration of the protective agent, the drum was drained and the protected skin was washed
with 300% of skin weight of water for 15 minutes at 5 rpm to remove any residual protective agent.
The wash water was drained completely.
Enzyme application
The pre-protected skin was treated in the processing drum with an aqueous solution comprising
100% of skin weight of water and 5% of skin weight of NOVOLIME® (an enzyme composition
comprising subtilisin and lipase) (Novozymes A/S, Denmark). Enzyme activity in NOVOLIME is
0.5AU/min as assessed by the method of Mozersky and Bailey 1992. The skin was agitated by
rotation for 2 hours at 5 rpm to allow the enzyme to fully penetrate into the wool follicle root of the
skin. The processing drum was then drained completely and the skin made ready for application of
the activating solution. Specifically the skin is drained of excess liquid by stacking in a pile
overnight.
In situ enzyme activation
The depilatory enzyme was activated in situ in the skin by painting the flesh side of the skin with an
activating composition or "paint" comprising
i) 5% hydrated calcium oxide
ii) 1.7% sodium sulfide
iii) 20% sodium hydroxide
39
The above concentrations in the paint are given as % wt/vol and correspond to less than 1% g Na2S
/ gSkin material since much less than a 1:1 ratio of paint to skin weight is applied. For example,
with reference to sodium sulfide, 1.7% sodium sulfide (60% active) applied at 600g/m² results in
about 0.3% g sodium sulfide/ gSkin material.
The activating paint also comprised 5% sodium sulfate as a deswelling agent to reduce looseness in
the final product. The activating paint as applied to the skin by spraying, rolling or brushing the
flesh side of the skin. Specifically in this case the paint was applied by brush. After the activating
paint was applied to the skin, the skin was held statically overnight (about 16 hours) to allow
enzyme activation and subsequent proteolysis in situ, at the depilatory active structures of the skin.
The wool was then removed from the skin manually by "pulling" or wiping off the wool with hands.
Neutralizing
The depilated skin was reweighed and processed with an aqueous neutralising solution (80% water,
.4% calcium chloride and 5.2% sucrose percentages based on skin weight) for 1 hour at 5 rpm.
The aqueous neutralizing solution was drained completely and the skin washed in 200% skin weight
water for 15 minutes at 5 rpm. The skin was then washed 3 further times for 15 minutes each in
200% skin weight water at 5 rpm with constant agitation. After the last wash, the skin was further
treated with an aqueous solution containing 100% skin weight water, 2% ammonium chloride, for
minutes at 5 rpm with constant agitation. This latter treatment is known in the art as the
"deliming" stage. After 2 minutes, 2% hydrogen peroxide was added and the skin processed for an
additional 75 minutes at 5 rpm with intermittent agitation.
After deliming, the pH of the skin was determined to be less than 9.0 by phenolphthalein staining of
a neck cross section.
40
The skin was washed an additional 3 times in 100% skin weight water for 20 minutes each with
agitation at 12 rpm. After the final wash was drained, the skin was treated in an aqueous solution
comprising 90% skin weight water, 20% sodium chloride and 0.1% UNISLIP FWTM (Union
Specialties, Mass, USA) is a "slip agent" composed of minerals and polymeric modifiers that stops
the skins from tangling. The use of UNISLIP FWTM is known in the art and the use of this slip agent
is common throughout the industry. In particular, UNISLIP FWTM is effective at stopping the skins
from tangling in the drum.
The skin was processed for 10 minutes with agitation at 12 rpm. After 10 minutes, a pre-mixed
composition comprising 0.06% fungicide (thiocyanomethylthio) benzothiazole (TCMTB), 10%
skin weight water and 2% sulphuric acid was added and the skin processed for an additional 1.5
hours with agitation at 12 rpm. The skins were then processed at 5rpm for 16 hours with constant
agitation then fully drained. The skin product (pickled skin) could then be processed to wet blue and
then crust leather using conventional standard processes know in the art, for example, as described
in Sharphouse 1971.
Proof of concept – enzyme depilation of THPS pre-protected skins
A two factor two level factorial experiment was carried out as a "proof of concept" to demonstrate
the superiority of the depilation method described herein as compared to other enzyme based or
conventional depilation methods. The overall results of the experiment are shown in Figure 1.
Four different skin treatment groups were tested comparatively as follows: skin treatment either
with or without pre-protection with THPS, and skin treatment either with or without the addition of
enzyme. The process used was that described in example 1 with the exception that the groups
without THPS (not protected) had 0% THPS added at the "pre-treatment with protective agent"
stage and the groups without enzyme (without enzyme) had 0% enzyme added at the "enzyme
application" stage. After pickling the skins were processed to crust leather using standard
41
conventional processes as known in the art. For each treatment group the overall depilation was
ranked, and the skins assessed for grain surface damage against a semi quantitative scale (Figure 1).
The results show that enzyme based depilation after pre-protection of the skin using THPS as
described in example 1 had a positive influence on the depilation, resulting in a better quality grain
surface (Figure 5). In contrast, the results of this comparative trial show that enzyme based
depilation without pre-protection results in a marked reduction in quality of the grain surface
(Figure 3). Overall, the use of a protective agent as described in example 1 had a positive influence
on the grain surface particularly for the skins treated with the enzyme (Figures 3 and 5).
Photomicrographs of the different skin treatments are shown in Figures 2-5. Figure 2 shows the
grain surface of crust leather produced from an un-protected (i.e., no THPS pre-treatment) skin that
was conventionally depilated; Figure 3 shows the grain surface of crust leather produced from an
un-protected skin that was enzyme depilated; Figure 4 shows the grain surface of crust leather
produced from a protected (i.e., pre-treated with THPS) skin that was conventionally depilated and
Figure 5 shows the grain surface of crust leather produced from a protected skin that was enzyme
depilated.
Alternative protective agents
To examine the efficacy of alternative protective agents, the process as described above in example
1 was carried out using a range of different regents in place of THPS at the "pretreatment with
protective agent" stage. After pickling the skins were processed to crust leather using standard
conventional processes. For each treatment group the overall depilation was ranked and the skins
assessed for grain surface damage against a semi quantitative scale (Figure 6). The skin in some
treatment groups was too damaged after depilation to continue processing and so no grain
assessment of the skins from these treatment groups was possible. The only protective agents used
in the enzyme based depilation process that provided protection to the skin grain after processing to
42
crust leather were THPS, biocide (potassium dimethyldithiocarbamate), gluteraldehyde, and
chromium sulphate. The results demonstrate that protection of the skin with THPS resulted in a
highly depilated skin with high grain quality after processing to crust leather as compared to the
other protective agents trialled (Figure 6). Treatment with THPS was significantly better than other
treatments with a score of 4, which corresponds only to some minor distortion to the grain pattern
whereas the next best treatments, those of biocide or glutaraldehyde had scores around 3 which
corresponds to major distortion of the grain surface with regions of the fine grain structure know to
the art as "enamel" completely destroyed exposing the fibrous material beneath.
Alternative enzymes
To examine the efficacy of different enzymes for depilation of skins according to the methods
disclosed herein, a range of different protective agents were trialled following the process of
example 1. In particular, a different commercial enzyme was used in place of NOVOLIMETM at the
"enzyme application" stage. After pickling the skins were processed to crust leather using standard
conventional processes.
For each treatment group the overall degree of depilation was ranked, the skins in each treatment
group were assessed for grain surface damage against a semi quantitative scale, the strength of the
skins in each treatment group was assessed using the standard method for double edge tear ISO//BS
EN 3377-2:2002, and the looseness of the leathers produced from the skins in each treatment group
was measured by non parametric comparison between skins against a qualitative sale of looseness
(Figure 7). The primary selection criteria in this work was to find a depilatory enzyme which when
used in the method of the invention generated the least damage in the form of grain damage or
looseness while still providing some degree of depilation. The results show that the two best
enzymes in terms of looseness were NUE and NOVOLIMETM. While Enzidase had a high score for
grain quality it was not significantly better than either NUE or NOVOLIMETM
.
43
Alternative sharpening agents
To examine the effect of different sharpening agents, particularly as alternatives to sodium sulfide, a
range of reducing agents were trialled using the process described in example 1. Specifically, a
different sharpening agent was used in place of sodium sulfide at the "in-situ enzyme activation"
stage. After pickling the skins were processed to crust leather using standard conventional
processes.
For each treatment group the overall depilation of the skin was ranked, the skins were assessed for
grain surface damage against a semi quantitative scale, the strength of the treated skins was assessed
using the standard method for double edge tear ISO//BS EN 3377-2:2002, and the looseness of the
leathers produced was measured by non parametric comparison between differently treated skins
against a qualitative sale of looseness. The results of this comparative trial are shown in Figure 8.
In some cases the treated skins were insufficiently depilated to enable continued processing and so
no results for grain surface, strength, or looseness were possible. The results show that a skin
processed without any sharpening agent had an extremely poor pull (i.e., poor depilation),
indicating that a sharpening agent such as sodium sulfide, is required. The two best alternatives to
sodium sulfide were the sulphur containing compounds, thioglycolic acid and 2-mercaptoethanol.
The use of thioglycolic acid resulted in a better quality leather as compared to the use of 2-
mercaptoethanol. The use of 3% thioglycolic acid in place of the sodium sulfide demonstrates that
the sulfide free depilation of skins following the enzyme depilation protocol set out in example 1
can provide high quality leather.
Example 2: Enzyme depilation of green sheep skins to produce a wet blue skin
All processing steps in this example were carried out at 25°C.
Pre-treatment with the protective agent
44
Process carried out as per example 1
Enzyme application
Process carried out as per example 1
In situ enzyme activation
Process carried out as per example 1
Neutralizing, degreasing, and tanning
As is typical for hide and deerskin processing percentages are given on the basis of the weight of
the hide or skin material. %wt/wt g reagent/g skin material.
The depilated skin was reweighed and processed with an aqueous neutralising solution (80% water,
.4% calcium chloride, 2% sodium sulphate and 5.2% sucrose percentages based on skin weight).
For 75 minutes at 5 rpm. The aqueous neutralizing solution was drained completely and the skin
washed in 200% skin weight water for 15 minutes at 10 rpm. The wash was then drained
completely and the skin processed in a degreasing wash comprising 100% water, 2% ammonium
chloride, 4% nonyl phenyl ethoxylate (Tetrapol LTN), and 0.2% Hydrogen peroxide for 60 minutes
at 45°C 10 rpm. The degreasing wash was then drained completely and the skin was processed with
150% water at 45°C for 15 minutes 10 rpm. A further 150% water was added with 1% sodium
dihydrogen phosphate and 1% nonyl phenyl ethoxylate for 60 minutes at 45°C 10 rpm. The wash
was then drained completely. A further three 150% water washes were then carried out for 15
minutes each at 45°C, 10 rpm with complete draining after each wash. A further 150% water wash
was carried out at 20°C for 15 minutes 10 rpm. This final was was then drained completely.
A cross section of the neck of the skin was taken and the pH of the skin checked using the indicator,
phenolphthalein to ensure that the pH was below 9 throughout the entire thickness of the skin. Next
45
100% water 0.1% unislip, 1% disodium phthalate was added and the skin processed for 10 minutes
at 10 rpm. Following this, 4.5% chromium sulphate was added and the skin was further processed
for 30 minutes at 10 rpm. The skin was then processed overnight at 40°C at 5rpm. The resulting
skin product (wet blue skin) was then ready to be processed to crust leather using conventional
standard processes know in the art as described in Sharphouse 1972.
Example 3: Enzyme processing of hides or deerskins to produce a wet blue product
In the following example, all processing steps were carried out at 25°C unless otherwise specified.
Pre-treatment with the protective agent
A pre-fleshed hide or deerskin was initially processed in a processing drum containing two volumes
of water (200% of hide or deerskin weight), 0.2% of a nonyl phenol ethoxylate degreasing agent
(Tetrapol LTN) and 3% protective agent, tetrakis hydroxyphosphonium sulfate (THPS). The hide or
deerskin was agitated by rotation for 3 hours at 2 rpm, allowing the protective agent to fully penetrate the raw hide or deerskin.
After penetration of the protective agent, the drum was drained and the protected hide or deerskin
was washed with 100% of hide or deerskin weight of water for 30 minutes at 10 rpm to remove any
residual protective agent. The wash water was drained completely.
Enzyme application
The pre-protected hide or deerskin was treated in the processing drum with an aqueous solution
comprising 100% of hide or deerskin weight of water and 2% of hide or deerskin weight of NOVOLIME® (an enzyme composition comprising subtilisin and lipase). Enzyme activity in NOVOLIME is 0.5AU/min as assessed by the method of Mozersky and Bailey 1992. The hide or deerskin was agitated by rotation for 3 hours at 2 rpm to allow the enzyme to fully penetrate into the
46
hair follicle root of the hide or deerskin. The processing drum was then drained completely and the
hide or deerskin made ready for application of the activating solution. Specifically the hide or deerskin was processed with and aqueous solution comprising 100% hide or deerskin weight of water
and 2% sodium sulphate. The drum was then drained completely.
In situ enzyme activation
The depilatory enzyme was activated in situ in the hide or deerskin by processing in the drum with
an aqueous solution comprising
i) 100% water
ii) 2% sodium sulphate
iii) 1% hydrated calcium oxide
iv) 10% sodium hydroxide
v) 1.2% thioglycollic acid
The hides or deerskins were then processed overnight intermittently; alternating between processing
and static holding as follows: processing at 2rpm for 1 minute each hour, and holding statically for
59 minutes each hour.
Neutralizing, degreasing, and tanning
After completely draining the depilatory process liquor the depilated hides or deerskins were processed with an aqueous neutralizing solution having (100% water and 2% sodium sulphate based on
hide or deerskin weight). Processing was carried out at 4rpm for 10 minutes. The aqueous neutralizing solution was completely drained and the hide or deerskin washed with 100% water at 4 rpm
for 10 minutes. The processing drum was then completely drained.
47
Deliming was carried out by processing the hide or deerskin in an aqueous deliming solution (500%
water and 0.5% ammonium chloride based on hide or deerskin weight). Deliming was carried out
for 15 minutes at 10 rpm. This initial deliming solution was completely drained from the processing drum. A further deliming process was carried out in aqueous solution (35% water and 0.5% hydrogen peroxide based on hide or deerskin weight. The hider or deerskin was processed at 30°C at
10rpm for 15. 2.5% ammonium chloride and 0.2% nonyl phenol ethoxylate degreasing agent
(Tetrapol LTN) based on hide or deerskin weight was then added to the drum. Further processing
was carried out at 30°C at 10rpm for 90 minutes.
A cross section of the neck of the hide or deerskin was taken and the pH of the hide or deerskin
checked using a phenolphthalein indicator to ensure the pH was below 9 throughout the thickness of
the hide or deerskin. The processing drum was completely drained and the hide or deerskin washed
twice with water (100% water based on hide or deerskin weight) with processing at 35°C, at 10 rpm
for 20 minutes.
The processing drum was drained and the hide or deerskin processed for 10 minutes at 10 rpm in
60% water and 8% sodium chloride based on the weight of the hide or deerskin. 1.2% sulphuric
acid (based on the weight of hide or skin) was added after being pre-diluted 10 fold in water and the
hide or deerskin processed for 120 minutes to reduce the pH of the processing solution to between
2.8-3.0. 6% chromium sulphate was then added to the processing solution and the hide or skin
processed for 180 minutes at 16 rpm. 0.35% magnesium oxide was then added and the hide or deerskin was processed overnight at 5rpm at 40°C. The hide or deerskin product (wet blue) processed
as above could then be further processed to crust leather using conventional standard processes
know in the art as described in Sharphouse 1972.
The skilled person will appreciate that the invention as set forth and described herein is not limited
solely to the aspects, embodiments, and examples as described, but also encompasses within the
48
scope of the invention, those variations and modifications of the invention as would be obvious to
the person of skill in the art (including the person of ordinary skill in the art) in view of the
disclosures provided herein and the common general knowledge. As would be appreciated by a
skilled person in the art, many variations are possible without departing from the scope of the
invention (as set out in the accompanying claims).
In addition, where features or aspects of the invention are described in terms of Markush groups,
those skilled in the art will recognise that the invention is also thereby described in terms of any
individual member or subgroup of members of the Markush group.
Example 4
Enzyme depilation of green sheep skins to produce a pickled skin –pre-acidification step
In the following example all processing steps were carried out between 20°C and 25°C.
Pre-acidificaiton
A pre-fleshed sheep skin was initially processed in a processing drum containing 10 volumes of
water (1000% of skin weight), and 0.3% formic acid and 1% D-limonene for about 60 minutes at
about 20°C (pH of about 4 or less).
Treatment with the protective agent
About 3% protective agent, tetrakis hydroxyphosphonium sulfate (THPS) (% wt/vol in solution)
was added. The skin was agitated by rotation for 105 minutes at 5 rpm, allowing the protective
agent to fully penetrate the raw skin.
After penetration of the protective agent, the drum was drained and the protected skin was washed
with 300% of skin weight of water for 15 minutes at 5 rpm to remove any residual protective agent.
49
The wash water was drained completely. After washing the skin was left overnight as a matter of
convenience. We have achieved the same results using skins or hides processed directly after
washing.
Enzyme application
The pre-protected skin was treated in the processing drum with an aqueous solution comprising
1000% of skin weight of water and 3% of skin weight of NOVOLIME® (an enzyme composition
comprising subtilisin and lipase) (Novozymes A/S, Denmark). Enzyme activity in NOVOLIME is
0.5AU/min as assessed by the method of Mozersky and Bailey 1992. The skin was agitated by
rotation for 5 hours at 5 rpm to allow the enzyme to fully penetrate into the wool follicle root of the
skin. The processing drum was then drained completely and the skin made ready for application of
the activating solution. Specifically the skin is drained of excess liquid by stacking in a pile
overnight.
In situ enzyme activation
The depilatory enzyme was activated in situ in the skin by painting the flesh side of the skin with an
activating composition or "paint" comprising:
i) 0.8% hydrated calcium oxide
ii) 1.3% sodium thioglycolate
iii) 10% sodium hydroxide
iv) 2% pre-gelatinised starch
The activating paint also comprised 4% sodium sulfate as a deswelling agent to reduce looseness in
the final product.
50
The activating paint as applied to the skin by spraying, rolling or brushing the flesh side of the skin.
Specifically in this case the paint was applied by brush. After the activating paint was applied to the
skin, the skin was held statically overnight (about 16 hours) to allow enzyme activation and
subsequent proteolysis in situ, at the depilatory active structures of the skin. The wool was then
removed from the skin manually by "pulling" or wiping off the wool with hands.
Neutralizing
The depilated skin was reweighed and processed with an aqueous neutralising solution (80% water,
.4% calcium chloride, 5.2% sucrose and 2% sodium sulfate, percentages based on skin weight)
for 1 hour at 5 rpm. The aqueous neutralizing solution was drained completely and the skin washed
in 200% skin weight water for 15 minutes at 5 rpm. The skin was then washed 3 further times for
minutes each in 200% skin weight water at 5 rpm with constant agitation. After the last wash,
the skin was further treated with an aqueous solution containing 100% skin weight water, 2%
ammonium chloride, for 20 minutes at 5 rpm with constant agitation. This latter treatment is known
in the art as the "deliming" stage. After 2 minutes, 2% hydrogen peroxide was added and the skin
processed for an additional 75 minutes at 5 rpm with intermittent agitation.
After deliming, the pH of the skin was determined to be less than 9.0 by phenolphthalein staining of
a neck cross section.
The skin was washed an additional 3 times in 100% skin weight water for 20 minutes each with
agitation at 12 rpm. After the final wash was drained, the skin was treated in an aqueous solution
comprising 90% skin weight water, 20% sodium chloride and 0.1% UNISLIP FWTM (Union
Specialties, Mass, USA) is a "slip agent" composed of minerals and polymeric modifiers that stops
the skins from tangling. The use of UNISLIP FWTM is known in the art and the use of this slip agent
is common throughout the industry. In particular, UNISLIP FWTM is effective at stopping the skins
from tangling in the drum.
51
The skin was processed for 10 minutes with agitation at 12 rpm. After 10 minutes, a pre-mixed
composition comprising 0.06% fungicide (thiocyanomethylthio) benzothiazole (TCMTB), 10%
skin weight water and 2% sulphuric acid was added and the skin processed for an additional 1.5
hours with agitation at 12 rpm. The skins were then processed at 5rpm for 16 hours with constant
agitation then fully drained. The skin product (pickled skin) could then be processed to wet blue and
then crust leather using conventional standard processes know in the art, for example, as described
in Sharphouse 1971.
The overall results achieved following the protocol in example 4 (not shown) were at least as good,
if not better than the results shown in Figure 1.
REFERENCES
(The following references are each incorporated by reference herein in their entireties)
Sharphouse, J. H. (1971). Leather technician's handbook. London: Vernon Lock.
Green, G. H. (1952). "Unhairing by means of enzymes (A review of literature)." Journal of the
Society of Leather Technologists and Chemists 36: 127-134.
Yates, J. R. (1972). "Studies in depilation X. The mechanism of the enzyme depilation process."
Journal of the Society of Leather Technologists and Chemists 56(5): 158-177.
Brady, D., J. R. Duncan, et al. (1989). "Enzyme depilatory studies part I. Review of enzyme
depilation." LIRI Research Bulletin 978.
Cantera, C. S. (2001). "Hair-saving unhairing process Part 1. Epidermis and the characteristics of
bovine hair." Journal of the Society of Leather Technologists and Chemists 85(1): 1-
.Sivasubramanian, S., B. Murali Manohar, et al. (2008). "Mechanism of enzymatic dehairing of
skins using a bacterial alkaline protease." Chemosphere 70: 1025-1034.
52
Wang, R., C. Min, et al. (2009). "Enzyme unhairing - An eco-friendly biotechnological process."
Journal of the Society of Leather Technologists and Chemists 93(2): 51-55.
Macedo, A. J., W. O. Beys de Silva, et al. (2005). "Novel Keratinase from Bacillus subtilis S14
exhibiting remarkable dehairing capabilities." Applied and environmental microbiology 71(1): 594-
596.
Saravanabhavan, P., P. Thanikaivelan, et al. (2005). "An enzymatic beamhouse process coupled
with semi-metal tanning and eco-benign post tanning leads to cleaner leather production." Journal
of the American Leather Chemists Association 100(5): 174-186.
Rose, C., L. Suguna, et al. (2007). Process for lime and sulphide free unhairing of skins or hides
using animal and/or plant enzymes. US, Council of scientific and industrial research.
Lowe, E. K. (1999). Enzyme depilation of ovine skins using NUE 0.6 MPX. Palmerston North,
New Zealand Leather and Shoe Research Association.
Lowe, E. K. (2000). Evaluation of SPIC depilatory enzyme under New Zealand operating
conditions. Palmerston North, New Zealand Leather and Shoe Research Association.
Cooper, S. M. and E. K. Lowe (1997). Enzyme depilation of ovine skins Part 1. Palmerston North,
New Zealand Leather and Shoe Research Association.
Cooper, S. M. (1997). Assessment of the dewooling potential of three enzymes. Palmerston North,
New Zealand Leather and Shoe Research Association.
Edmonds, R. (2012). Part 1- Sulphide free enzyme depilation - towards solving the key issues.
Proceedings of the 63rd LASRA Conference. Wellington, New Zealand Leather and Shoe Research
Association. 63: 98-119.
53
Coulson, R. G. (1969). "The SATRA Break/Pipiness Scale." Journal of the American Leather
Chemists Association 64: 648.
Cantera, C. S. (2001). "Hair-saving unhairing process Part 2. Immunisation phenomenon." Journal
of the Society of Leather Technologists and Chemists 85(2): 47-51.
Cantera, C. S. (2001). "Hair-saving unhairing process Part 3. "Cementing substances" and the
basement membrane." Journal of the Society of Leather Technologists and Chemists 85(3): 93-99
Cantera, C. S. (2001). "Hair-saving unhairing process Part 4. Remarks on the evolution of the
investigations on enzyme unhairing." Journal of the Society of Leather Technologists and Chemists
85(4): 125-132.
Cantera, C. S., L. Goya, et al. (2003). "Hair saving unhairing process. Part 5 characterisation of
enzymatic preparations applied in soaking and unhairing processes." Journal of the Society of
Leather Technologists and Chemists 87(2): 69-77
Brady, D., J. R. Duncan, et al. (1989). "Enzyme depilatory studies part III. A model for proteolytic
depilation of skins." LIRI Research Bulletin 982.
Wang, Y., Z. Li, et al. (2005). "Study on changes of collagen fibril structure in pigskin tissue after
enzyme treatment." Journal of the Society of Leather Technologists and Chemists 89(2): 47-56.
Felicjaniak, B. (1985). "Studies in enzymatic unhairing: Part I. The influence of pigskin alkalisation
on destruction of skin grain during depilation with pancreatic enzymes." Journal of the Society of
Leather Technologists and Chemists 69(6): 160-163.
Tandt, H., A. E. Russell, et al. (1997). Inhibition of proteolytic activity causing grain enamel in
leather. 24th IULTCS Congress proceedings.
54
Defect processing BLC leather technologies centre, (2001). "Keep your grain on: Tanners' dilemma." Leather International 203(4710): 114-115.
Hawkins, S. C. and J. Wassenberg (1997). Endogenous enzyme fellmongering - skin structure and
properties. 24th IULTCS Congress proceedings, London.
Covington, A. D. (2009). Tanning chemistry. The science of leather. Cambridge, The Royal Society
of Chemistry.
Bienkiewicz, K., Ed. (1983). Physical chemistry of leather making. Malabar, Florida, Robert E.
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Carrie, M. S. and F. W. Woodroffe (1960). Fellmongers handbook. Wellington, R.E. Owen, Government printer.
ISO//BS EN 3377-2:2002: Physical and mechanical tests - Determination of tear load - Part 2:
Double edge tear
Claims (56)
1. A method for removing wool or hair from at least one raw skin or hide, the skin or hide having a flesh side and a grain side, the method comprising a) contacting the skin or hide with a composition comprising a protective agent, b) contacting the skin or hide with a composition comprising a depilatory enzyme that is active at an alkaline pH greater than about 8, c) contacting the skin or hide with an activating composition comprising a base and a deswelling agent, wherein the base activates the depilatory enzyme in b) to act on the depilatory active structures in the skin or hide, and d) removing the wool or hair from the skin or hide.
2. The method of claim 1, wherein the method further comprises e) neutralizing the base on and/or in the skin or hide.
3. The method of claim 1 or claim 2, wherein the method further comprises f) washing the skin or hide with water between a) and b).
4. The method of claim 2 or claim 3, wherein removing the wool or hair from the skin or hide is carried out after neutralizing the base on and/or in the skin or hide.
5. The method of any one of claims 2 to 4, wherein the method further comprises g) removing a neutralizing agent that has been used to neutralize the base on and/or in the skin or hide.
6. The method of claim 5, wherein the method further comprises 56 h) washing the skin or hide in water after g).
7. The method of any one of claims 1 to 6, wherein the method further comprises i) processing the skin or hide using conventional deliming and then pickling techniques to produce a pickled skin or a pickled hide.
8. The method of any one of claims 1 to 6, wherein the method further comprises j) degreasing the skin or hide followed by processing the skin or hide directly to wet blue without pickling.
9. The method of claim 7 or claim 8, wherein the method further comprises k) processing the pickled or wet blue skin or hide into leather.
10. A method for removing wool or hair from at least one raw skin or hide, the skin or hide having a flesh side and a grain side, the method comprising a) contacting the skin or hide with a composition comprising a tetrakis (hydroxymethyl) phosphine (THP) compound, a tetrakis (hydroxymethyl) phosphonium salt (a THP salt), a THP condensate, or oxazolidine, b) contacting the skin or hide with a composition comprising an alkaline serine protease in a substantially inactive state, c) contacting the skin or hide with an activating composition comprising hydrated calcium oxide, thioglycolic acid, sodium sulfate and sodium hydroxide to activate the alkaline serine protease in b), and d) removing the wool or hair from the skin or hide. 57
11. The method of claim 10, wherein the method further comprises e) contacting the skin or hide with a neutralizing agent comprising sucrose and calcium chloride to reduce the pH on and/or in the skin or hide.
12. The method of claim 10 or claim 11, wherein the method comprises f) washing the skin or hide with water between a) and b).
13. A method for removing wool or hair from at least one raw skin or hide, the skin or hide each having a flesh side and a grain side, the method comprising a) contacting the skin or hide with a composition comprising a protein cross-linking agent, b) contacting the skin or hide with a composition comprising a depilatory enzyme that is substantially inactive at the pH of the composition, c) contacting the skin or hide with an activating composition comprising an agent that activates the depilatory enzyme in b), and a deswelling agent, and d) removing the wool or hair from the skin or hide.
14. The method of claim 13, wherein the method comprises e) washing the skin or hide with water between a) and step b).
15. The method of claim 13 or claim 14, wherein the contacting in c) is contacting the flesh side of the skin or hide with the activating composition.
16. A method for removing wool or hair from at least one skin or hide, the skin or hide each having a flesh side and a grain side, the method comprising 58 a) contacting the skin or hide with a composition comprising a protein cross-linking agent, b) contacting the skin or hide with a composition comprising a depilatory enzyme under conditions that maintain the enzyme in a substantially inactive state, c) contacting the flesh side of the skin or hide with an activating composition comprising an activating agent to activate the depilatory enzyme in b), and d) removing the wool or hair from the skin or hide.
17. The method of claim 16, wherein the method comprises e) washing the skin or hide with water between a) and b).
18. The method of claim 16 or claim 17, wherein the activating composition in c) further comprises a deswelling agent.
19. The method of any one of claims 1 to 18, wherein the method does not use sulfide.
20. The method of any one of claims 1 to 18, wherein the method uses sulfide at a concentration of less than about 1% Na2S (gNa2S/gSkin material).
21. The method of claim 20, wherein the method uses sodium sulfide at a concentration of about 0.7% gNa2S/gSkin material or less.
22. A method for removing wool or hair from at least one raw skin or hide, the skin or hide having a flesh side and a grain side, the method comprising a) contacting the skin or hide with an composition comprising a protective agent, 59 b) contacting the skin or hide with a composition comprising a depilatory enzyme that is active at an alkaline pH, c) contacting the flesh side of the skin or hide with an activating composition comprising a base and a deswelling agent, wherein the base activates the depilatory enzyme in b) to act on the depilatory active structures in the skin or hide, and d) removing the wool or hair from the skin or hide, wherein the method either i) does not use a sulfide, or ii) uses sodium sulfide at a concentration of less than about 1% Na2S (g Na2S /gSkin material).
23. The method of claim 22, wherein the method further comprises e) washing the skin or hide with water between a) and b).
24. The method of claim 22 or claim 23, wherein the method uses sodium sulfide at a concentration of about 0.5 to about 0.9% g Na2S /gSkin material.
25. The method of claim 22 or claim 23, wherein the method uses sodium sulfide at a concentration of about 0.7% g Na2S /gSkin material or less.
26. A method for removing wool or hair from at least one raw skin or hide, the skin or hide having a flesh side and a grain side, the method comprising a) contacting the skin or hide with a composition comprising about 2% tetrakis (hydroxymethyl) phosphonium sulfate (THPS) (wtTHPS/wtSkin material) for about three hours, b) contacting the skin or hide for about 2 hours with a composition comprising about 2% wt/vol of a depilatory enzyme subtilisin having an activity of 0.5AU/min, the composition having a pH of about 7, 60 c) contacting the skin or hide for about 2 to about 16 hours with an activating composition comprising about 5% hydrated calcium oxide (wt/vol), about 3% thioglycolic acid (wt/vol), about 0.5% sodium sulfate (wt/vol) and about 10% sodium hydroxide (wt/vol) to activate the subtilisin, d) removing the wool or hair from the skin or hide.
27. The method of claim 26, wherein the method further comprises e) washing the skin or hide with water between a) and b).
28. The method of claim 26 or claim 27, wherein the method further comprises neutralizing a base on and/or in the skin or hide by contacting the skin or hide for about 2 hours with a neutralizing agent comprising sucrose and calcium chloride.
29. The method of claim 28, wherein the method further comprises removing the neutralizing agent that has been used to neutralize the base on and/or in the skin or hide.
30. The method of claim 29, wherein the method further comprises washing the skin or hide with water after removing the neutralizing agent that has been used to neutralize the base on and/or in the skin or hide.
31. The method of claim 29 wherein the method further comprises washing the skin or hide with water between a) and b), and washing the skin or hide with water after removing the neutralizing agent that has been used to neutralize the base on and/or in the skin or hide.
32. The method of any one of claims 26 to 31, wherein the method further comprises 61 processing the skin or hide using conventional deliming and then pickling techniques to produce pickled skin or pickled hide.
33. The method of any one of claims 26 to 31, wherein the method comprises degreasing the skin or hide followed by processing the skin or hide directly to wet blue without pickling.
34. The method of claim 33, wherein the method further comprises processing the pickled or wet blue skin or hide into leather.
35. The method of any one of claims 26 to 34, wherein the method does not use sulfide.
36. The method of any one of claims 26 to 34, wherein the method uses sodium sulfide at a concentration of about 0.7% (gNa2S /gSkin material) or less.
37. A method for removing wool or hair from at least one raw skin or hide, the skin or hide having a flesh side and a grain side, the method comprising a) contacting the skin or hide with a composition comprising about 3% tetrakis (hydroxymethyl) phosphonium sulfate (THPS) (wtTHPS/wtSkin material) for about one to about three hours, b) contacting the skin or hide for about two to about five hours with a composition comprising about 3% wt/vol of a depilatory enzyme subtilisin having an activity of 0.5AU/min, the composition having a pH of about 7, c) contacting the skin or hide for about 2 to about 16 hours with an activating composition comprising about 1% hydrated calcium oxide (wt/vol), about 1% sodium thioglycolate (wt/vol), about 0.5% sodium sulfate (wt/vol) and about 12.5% sodium hydroxide (wt/vol) to 62 activate the subtilisin, d) removing the wool or hair from the skin or hide.
38. The method of claim 37, wherein the method further comprises e) washing the skin or hide with water between a) and b).
39. The method of claim 37 or claim 38, wherein the method further comprises neutralizing a base on and/or in the skin or hide by contacting the skin or hide for about 2 hours with a neutralizing agent comprising sodium sulfate, sucrose and calcium chloride.
40. The method of claim 38, wherein the method further comprises removing the neutralizing agent that has been used to neutralize the base on and/or in the skin or hide.
41. The method of claim 40, wherein the method further comprises washing the skin or hide with water after removing the neutralizing agent that has been used to neutralize the base on and/or in the skin or hide.
42. The method of claim 40 wherein the method further comprises washing the skin or hide with water between a) and b), and washing the skin or hide with water after removing the neutralizing agent that has been used to neutralize the base on and/or in the skin or hide.
43. The method of any one of claims 37 to 42, wherein the method further comprises processing the skin or hide using conventional deliming and then pickling techniques to produce pickled skin or pickled hide. 63
44. The method of any one of claims 37 to 42, wherein the method comprises degreasing the skin or hide followed by processing the skin or hide directly to wet blue without pickling.
45. The method of claim 44, wherein the method further comprises processing the pickled or wet blue skin or hide into leather.
46. The method of any one of claims 37 to 45, wherein the method does not use sulfide.
47. The method of any one of claims 1 to 46, wherein the method comprises before a), contacting the skin or hide with a composition comprising an acid and a penetration enhancer.
48. The method of claim 47, wherein the acid is formic acid.
49. The method of claim 47, wherein the penetration enhancer is D-limonene.
50. The method of claim 48, wherein the concentration of formic acid is about 0.3% based on skin weight.
51. The method of claim 49, wherein the concentration of D-limonene is about 1% based on skin weight.
52. The method of claim 47, wherein the composition comprises about 0.3% formic acid based on skin weight and about 1% D-limonene based on skin weight.
53. The method of any one of claims 47 to 52 wherein the contacting with the composition 64 comprising the acid and the penetration enhancer is for about 30 to about 90 minutes.
54. The method of claim 53 wherein the contacting with the composition comprising the acid and the penetration enhancer is for about 60 minutes.
55. The method as claimed in any one of claims 1 to 54 substantially as herein described with reference to any example thereof.
56. A skin or hide from which wool or hair has been removed according to a method of any one of claims 1 to 54.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2013901710A AU2013901710A0 (en) | 2013-05-15 | Method of depilation | |
AU2013901710 | 2013-05-15 |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ624685A NZ624685A (en) | 2015-09-25 |
NZ624685B true NZ624685B (en) | 2016-01-06 |
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