CA1267753A - Process for the preparation of fish skin - Google Patents
Process for the preparation of fish skinInfo
- Publication number
- CA1267753A CA1267753A CA000526836A CA526836A CA1267753A CA 1267753 A CA1267753 A CA 1267753A CA 000526836 A CA000526836 A CA 000526836A CA 526836 A CA526836 A CA 526836A CA 1267753 A CA1267753 A CA 1267753A
- Authority
- CA
- Canada
- Prior art keywords
- skins
- bath
- tanning
- combination
- group
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 title claims abstract description 34
- 241000251468 Actinopterygii Species 0.000 title claims abstract description 21
- 238000002360 preparation method Methods 0.000 title claims abstract description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000002253 acid Substances 0.000 claims abstract description 12
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims abstract description 8
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 7
- 150000001340 alkali metals Chemical class 0.000 claims abstract description 7
- 239000011651 chromium Substances 0.000 claims abstract description 7
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 7
- 102000004190 Enzymes Human genes 0.000 claims abstract description 6
- 108090000790 Enzymes Proteins 0.000 claims abstract description 6
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 6
- 238000005406 washing Methods 0.000 claims abstract description 6
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 4
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 4
- 238000004043 dyeing Methods 0.000 claims abstract description 4
- 239000004571 lime Substances 0.000 claims abstract description 4
- 238000005554 pickling Methods 0.000 claims abstract description 4
- 230000000284 resting effect Effects 0.000 claims abstract description 4
- 150000003839 salts Chemical class 0.000 claims abstract description 4
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 claims abstract description 3
- 159000000013 aluminium salts Chemical class 0.000 claims abstract description 3
- 150000001449 anionic compounds Chemical class 0.000 claims abstract description 3
- 125000000129 anionic group Chemical group 0.000 claims abstract description 3
- 150000008040 ionic compounds Chemical class 0.000 claims abstract description 3
- 230000001376 precipitating effect Effects 0.000 claims abstract description 3
- 239000002904 solvent Substances 0.000 claims abstract description 3
- 238000003756 stirring Methods 0.000 claims abstract description 3
- 238000005238 degreasing Methods 0.000 claims abstract 7
- 229940124091 Keratolytic Drugs 0.000 claims abstract 2
- 230000001530 keratinolytic effect Effects 0.000 claims abstract 2
- 150000002894 organic compounds Chemical class 0.000 claims abstract 2
- 239000010985 leather Substances 0.000 claims description 21
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims description 17
- 239000007859 condensation product Substances 0.000 claims description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 3
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 claims description 3
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims description 3
- JXLHNMVSKXFWAO-UHFFFAOYSA-N azane;7-fluoro-2,1,3-benzoxadiazole-4-sulfonic acid Chemical compound N.OS(=O)(=O)C1=CC=C(F)C2=NON=C12 JXLHNMVSKXFWAO-UHFFFAOYSA-N 0.000 claims description 3
- 150000001844 chromium Chemical class 0.000 claims description 3
- 229910021653 sulphate ion Inorganic materials 0.000 claims description 3
- 125000002947 alkylene group Chemical group 0.000 claims description 2
- 239000000243 solution Substances 0.000 claims 2
- 238000007385 chemical modification Methods 0.000 claims 1
- 229920005610 lignin Polymers 0.000 claims 1
- 238000001035 drying Methods 0.000 abstract description 5
- 125000003118 aryl group Chemical group 0.000 abstract description 3
- 102000008186 Collagen Human genes 0.000 description 6
- 108010035532 Collagen Proteins 0.000 description 6
- 229920001436 collagen Polymers 0.000 description 6
- 239000000126 substance Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- 150000007524 organic acids Chemical class 0.000 description 3
- -1 phenol sulpho Chemical class 0.000 description 3
- 241000251730 Chondrichthyes Species 0.000 description 2
- 102000011782 Keratins Human genes 0.000 description 2
- 108010076876 Keratins Proteins 0.000 description 2
- 241000270322 Lepidosauria Species 0.000 description 2
- 241000124008 Mammalia Species 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 2
- 235000013311 vegetables Nutrition 0.000 description 2
- IULJSGIJJZZUMF-UHFFFAOYSA-N 2-hydroxybenzenesulfonic acid Chemical compound OC1=CC=CC=C1S(O)(=O)=O IULJSGIJJZZUMF-UHFFFAOYSA-N 0.000 description 1
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- 241000283690 Bos taurus Species 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 241000283707 Capra Species 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 241000723298 Dicentrarchus labrax Species 0.000 description 1
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 1
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N Glutaraldehyde Chemical compound O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 241001494479 Pecora Species 0.000 description 1
- 241000282887 Suidae Species 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 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 1
- 238000004040 coloring Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 210000000056 organ Anatomy 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 235000004252 protein component Nutrition 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 230000037307 sensitive skin Effects 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
Landscapes
- Treatment And Processing Of Natural Fur Or Leather (AREA)
Abstract
Abstract of the Disclosure A process for the preparation of fish skin consists in a) descaling and at least partially degreasing of the skins in a bath containing one or more surface active anionic, non-ionic or amphoteric organic compounds in a small amount of water, b) treating the skins in a second bath containing a keratolytic enzyme or an alkali metal sulphide and/or alkali metal hydrogen sulphide, lime and water under stirring and optionally further removing the sulphide by adding a precipitating agent for the sulphide and washing, c) degreasing the skins simultaneously with step b) or in a separate bath by means of surface active non-ionic and/or anionic compounds and/or solvents and/or enzymes, d) pretanning the skins with an aromatic syntan at a tem-perature of below 20°C and a pH of 5 to 8, e) pickling the skins in an acid and salt containing pickling bath at a pH of 1.5 to 4 and f) tanning the skins in a.manner known per se with a chromium and/or syntan tanning solution and g) optionally, after a resting period of several hours, washing and retanning the skins with chromium or aluminium salts and/o r syntans and subsequently, if desired,dyeing and fat liquoring in a known manner, drying and further mechanical processing of the skins.
Description
~267753 Field of the Invention ~ . . _ The invention concerns a process for the preparation of fish skin.
The preparation of leather originating from animals comprises customarily the exposure of the inner or true skin, optionally pretanning followed by tanning and after-treating the leather comprising dyeing, fat-liquoring, drying and finishing as well as mechanical processing.
Although a highly developed technique for the prepara-tion of leather from skins of mammals such as cows, pigs, sheep and goats exists the preparation of leather-from fish skin has been neglected because of the difficulties arising from the special structure of the collagen of the inner skin with the exception of shark skin which has another structure. The processes of the customary pretreatment of the so-called fish skin pelt by preservation, drying, softening in a water bath, descaling and depilating, ~espectively by lime treatment, i.e., decomposing of the keratin by means of calcium hydroxide and sodium sulphide, deliming and scouring as well as pickling in acid and salt containing liquors and tanning in rotating tanning drums containing tanning substances such as chromium salts or tanning substances of plant origin, further washing, fat liquoring, drying, optionally colouring and mechanical tr0atm~nt (EinLsh1ny) results usually in soEt ~nd limp leather or t:oo rigid leather similar to the leather of repti]e skin, but not leather that is simultaneously pliable, soft and of good strength to the touch.
~267753 -lA-Background and Discussion of Pr_or Art It is known from U.S. patent 2,700,590 to use tanning agents having a high adstringent effect such as the combination of certain vegetable extracts and a condensation product 77~;3 of a phenol sulpho acid with formaldehyde for tanning the skins of teleosteans, sharks and mammals under special consideration of the easy hydrolysi~of the fish collagen. This allows the tanning and th~s preservation of skin but the leather becomes very rigid similar to reptile leather but without its pliability and softness. Further the descaling and the removal of the keratin and of other protein compo-nents of the skin is/menttioned which constitutes a major problem in the tanning of fish skin.
lG Further according to U.S. patent 4,379,708 fish skin tanning is carried out by adjusting the pH of the skin to 1~5 to 3O5 and tanning in two steps by using first a diluted liquor below 35C and finally a concentrated liquor at a temperature exceeding 35C, followed by washing and fat liquoring and adjusting to a pH of at least 6, resulting a leather of a certain softness.
However a good tensilé strength and a full feel as well as a pliability of the leather product as well as the necessary strength against the effects of the chemical ad-2G stringent during the process are not reached.
In French patent 729,242 a tanning method for fish skin is disclosed according to which syntans and subsequently vegetable tanning agents or a mixture of both are used followed by chromium tanning. By this method however, neither the softness nor the pliability of the leather is reached that is held to be desirable.
The process for tanning fish skin is quite different from the process of tanning mammalian skin because of the great difference in the molecularstructure of the collagen of 0 fish skin on one hand and of mammalian skin on the other hand. ~ish collagen has a linear structure contrary to the branched structure o~ mammalian collagen. This explains the remarkable di~ference in the bonds which may be tanned with respect to strength against the temperatures of hydro-lysis-and the tensile strength.
Further there is an important difference between the tempera-tures of hydrolysis of the skins. With fish skin this value is about 20C lower for almost all fish species than that of mammalian skin. This means that all processes prior to 1C tanning must be carried out at 20C below the temperature which is recommended for the pretreatment of mammalian skin.
De ~ ferred Embodiment Object of the invention is a process which allows to produce soft and pliable leather from fish skin which is nonetheless of high strength.
Another object of the invention is a process which allows the processing of sensitive skin of fish species which may not be processed by other processes known in the art.
'~he process of the invention is characterized in that 2G a) fish skins are descaled and at least partially deg~ased in a bath containing one or more sur~ace active anionic, non-ionic or amphoteric organ~c compounds in a small amount of water, b) the skinsare treated in a second bath containing a heratolytic enzyme or an alkali metal sulphideand/or an alkali metal hydrogen sulphide, lime and water under stirring and further optionally the sulphide is removed by adding a precipitating agent for the sulphide, r 12~i7753 c) the skins are degreased either simultaneously in step b) or in a separate bath by means of surface active non-ionic and/or anionic compounds and/or solvents and/or enzymes, d) the skins are pretanned with an aromatic syntan at a temperature of below 20C and a pH of 5 to 8, e) the skins are pickled in a bath containing acid and salt at a pH of 1~5 to 4 and f) the skins are tanned in a manner known per se with a chromium and/or syntan tanning solution and g) the skins are optionally washed and retanned with chromium or aluminium salts and/or syntans after a resting period of several hours, followed, if desired, by dyeing and fat liquoring in a known manner, drying and further mechanical processing of the skins.
According to a preferred embodiment of the invention in step,a) a condensation product of alkylene oxidewith a C5- to C20-alkanol, a higher fatty acit ester with a C5 - to C20-alkanol or a fatty or fat.ty alkohol sulphonate or -sulphate is used as the surface active compound.
The preparation of leather originating from animals comprises customarily the exposure of the inner or true skin, optionally pretanning followed by tanning and after-treating the leather comprising dyeing, fat-liquoring, drying and finishing as well as mechanical processing.
Although a highly developed technique for the prepara-tion of leather from skins of mammals such as cows, pigs, sheep and goats exists the preparation of leather-from fish skin has been neglected because of the difficulties arising from the special structure of the collagen of the inner skin with the exception of shark skin which has another structure. The processes of the customary pretreatment of the so-called fish skin pelt by preservation, drying, softening in a water bath, descaling and depilating, ~espectively by lime treatment, i.e., decomposing of the keratin by means of calcium hydroxide and sodium sulphide, deliming and scouring as well as pickling in acid and salt containing liquors and tanning in rotating tanning drums containing tanning substances such as chromium salts or tanning substances of plant origin, further washing, fat liquoring, drying, optionally colouring and mechanical tr0atm~nt (EinLsh1ny) results usually in soEt ~nd limp leather or t:oo rigid leather similar to the leather of repti]e skin, but not leather that is simultaneously pliable, soft and of good strength to the touch.
~267753 -lA-Background and Discussion of Pr_or Art It is known from U.S. patent 2,700,590 to use tanning agents having a high adstringent effect such as the combination of certain vegetable extracts and a condensation product 77~;3 of a phenol sulpho acid with formaldehyde for tanning the skins of teleosteans, sharks and mammals under special consideration of the easy hydrolysi~of the fish collagen. This allows the tanning and th~s preservation of skin but the leather becomes very rigid similar to reptile leather but without its pliability and softness. Further the descaling and the removal of the keratin and of other protein compo-nents of the skin is/menttioned which constitutes a major problem in the tanning of fish skin.
lG Further according to U.S. patent 4,379,708 fish skin tanning is carried out by adjusting the pH of the skin to 1~5 to 3O5 and tanning in two steps by using first a diluted liquor below 35C and finally a concentrated liquor at a temperature exceeding 35C, followed by washing and fat liquoring and adjusting to a pH of at least 6, resulting a leather of a certain softness.
However a good tensilé strength and a full feel as well as a pliability of the leather product as well as the necessary strength against the effects of the chemical ad-2G stringent during the process are not reached.
In French patent 729,242 a tanning method for fish skin is disclosed according to which syntans and subsequently vegetable tanning agents or a mixture of both are used followed by chromium tanning. By this method however, neither the softness nor the pliability of the leather is reached that is held to be desirable.
The process for tanning fish skin is quite different from the process of tanning mammalian skin because of the great difference in the molecularstructure of the collagen of 0 fish skin on one hand and of mammalian skin on the other hand. ~ish collagen has a linear structure contrary to the branched structure o~ mammalian collagen. This explains the remarkable di~ference in the bonds which may be tanned with respect to strength against the temperatures of hydro-lysis-and the tensile strength.
Further there is an important difference between the tempera-tures of hydrolysis of the skins. With fish skin this value is about 20C lower for almost all fish species than that of mammalian skin. This means that all processes prior to 1C tanning must be carried out at 20C below the temperature which is recommended for the pretreatment of mammalian skin.
De ~ ferred Embodiment Object of the invention is a process which allows to produce soft and pliable leather from fish skin which is nonetheless of high strength.
Another object of the invention is a process which allows the processing of sensitive skin of fish species which may not be processed by other processes known in the art.
'~he process of the invention is characterized in that 2G a) fish skins are descaled and at least partially deg~ased in a bath containing one or more sur~ace active anionic, non-ionic or amphoteric organ~c compounds in a small amount of water, b) the skinsare treated in a second bath containing a heratolytic enzyme or an alkali metal sulphideand/or an alkali metal hydrogen sulphide, lime and water under stirring and further optionally the sulphide is removed by adding a precipitating agent for the sulphide, r 12~i7753 c) the skins are degreased either simultaneously in step b) or in a separate bath by means of surface active non-ionic and/or anionic compounds and/or solvents and/or enzymes, d) the skins are pretanned with an aromatic syntan at a temperature of below 20C and a pH of 5 to 8, e) the skins are pickled in a bath containing acid and salt at a pH of 1~5 to 4 and f) the skins are tanned in a manner known per se with a chromium and/or syntan tanning solution and g) the skins are optionally washed and retanned with chromium or aluminium salts and/or syntans after a resting period of several hours, followed, if desired, by dyeing and fat liquoring in a known manner, drying and further mechanical processing of the skins.
According to a preferred embodiment of the invention in step,a) a condensation product of alkylene oxidewith a C5- to C20-alkanol, a higher fatty acit ester with a C5 - to C20-alkanol or a fatty or fat.ty alkohol sulphonate or -sulphate is used as the surface active compound.
2~ According to another preferred embodiment pretanning in step d) is carried out with the condensation product of an aromatic mono-, di- or trisulphonic acid with formaldehyde. The pre-ferred mono-, di- or trisulphonic acid is derived from phenol, naphthaline and/or lig~in.
Whereas according to the invention use is made from chemi-cals and liquors known in the production of leather the in-ventive process steps are different in the order of the application and at least partially in the conditions of the process. It is surprising and by no means obvious that fi~lskin could be processed to give leather ready for any use with especially good properties.
i;~6~7~i3 Example The process of the invention was applied to tanning of the skin of the Sea-Bass which belongs to the family of Seranidae.
The amounts given refer to 1 000 g of fresh or rewetted skins.
a) The skins were treated in a drum containing 5 to 12 g of a condensation product of ethylene oxide with an C8-C12-alkanol mixture in 50 to 100 g of water for 15 to 60 min:.
Then the skins were washed by adding water until a bath ratio of 100 to 300~ was reached.
b) To the skins in the drum there were added 1000 to 3000 g of water, 3 to 5 g!~f sodium sulphide and 6 to 14 g of calcium hydroxyde in order to prepare the collagen for the tanning process. This bath was moved for 20 to 60 mins.
Subsequently the skins were rinsed for at least 20 mins.
with a large amount of water.
c) To the rinsed skinS 1000 tO 2000 g of water were added as well as 15 tO 30 g of an inorganic salt that reacts with the alkaline sulphur compound of the preceding step and forms an lnsoluble sal~, such a~ calcil~m carbonate.
Further 3 to 8 g of a soluble sodium salt of an organic acid, namely phenol sulphonic acid, were added and the bath was moved for 20 tO 30 mins. until the chemicals used in step b) were fully precipitated, after that the skins were rinsed with water for 15 mins.
~2677~3 d) To the rinsed skins 1000 g of water and 5 to 15 g of a condensation product of formaldehyde with phenol or naphthali~ which as able to react at a temperature below 19C and a pH of between 5 and 8 was added. This treatment was repeated for 15 to 45 min. under continous monement of the drum.
Subsequently 2000 g of water and 140 g o~ sodium chloride were added and the drum was further moved for 15 mins.
Then 18 g of a preferably organic acid, namely formic acid, was added (another acid, such as an inorganic acid, would also be applicable~ to reach a pH of 1-5 to 3 5.
The bath was moved for further 120 to 180 mins.
e) To the bath 25 to 40 g of tanning agent were added, preferably a chromium sulfate of a basicity of 33%.
Alternate resting and moving periods up to a about 12 hours of total treatment were carried out. Although the bath can further be used for the following steps it was removed and the process carried out further with a new bath.
f) A new bath for a common chromium tanning process with 9% chromium salt of 33% basicity was used which was basified in the usual manner. Then the skins were allowed to rest on trusses for 8 hours.
g) The skins were retanned with a blend of two syntans, both being condensation products of formalin with different organic acids, namely a blend of glutaraldehyde and a condensate of naphthaline disulphonic acid with formaldehyde.
Subsequently the leather was finished by usual and fat liquoring and mechanical treatment.
~267'7~3 The resulting leather had a certain similarity with reptile leather of about comparable strength but was pliable and flexible such as a fine leather for pursPs etc.
,. .
Whereas according to the invention use is made from chemi-cals and liquors known in the production of leather the in-ventive process steps are different in the order of the application and at least partially in the conditions of the process. It is surprising and by no means obvious that fi~lskin could be processed to give leather ready for any use with especially good properties.
i;~6~7~i3 Example The process of the invention was applied to tanning of the skin of the Sea-Bass which belongs to the family of Seranidae.
The amounts given refer to 1 000 g of fresh or rewetted skins.
a) The skins were treated in a drum containing 5 to 12 g of a condensation product of ethylene oxide with an C8-C12-alkanol mixture in 50 to 100 g of water for 15 to 60 min:.
Then the skins were washed by adding water until a bath ratio of 100 to 300~ was reached.
b) To the skins in the drum there were added 1000 to 3000 g of water, 3 to 5 g!~f sodium sulphide and 6 to 14 g of calcium hydroxyde in order to prepare the collagen for the tanning process. This bath was moved for 20 to 60 mins.
Subsequently the skins were rinsed for at least 20 mins.
with a large amount of water.
c) To the rinsed skinS 1000 tO 2000 g of water were added as well as 15 tO 30 g of an inorganic salt that reacts with the alkaline sulphur compound of the preceding step and forms an lnsoluble sal~, such a~ calcil~m carbonate.
Further 3 to 8 g of a soluble sodium salt of an organic acid, namely phenol sulphonic acid, were added and the bath was moved for 20 tO 30 mins. until the chemicals used in step b) were fully precipitated, after that the skins were rinsed with water for 15 mins.
~2677~3 d) To the rinsed skins 1000 g of water and 5 to 15 g of a condensation product of formaldehyde with phenol or naphthali~ which as able to react at a temperature below 19C and a pH of between 5 and 8 was added. This treatment was repeated for 15 to 45 min. under continous monement of the drum.
Subsequently 2000 g of water and 140 g o~ sodium chloride were added and the drum was further moved for 15 mins.
Then 18 g of a preferably organic acid, namely formic acid, was added (another acid, such as an inorganic acid, would also be applicable~ to reach a pH of 1-5 to 3 5.
The bath was moved for further 120 to 180 mins.
e) To the bath 25 to 40 g of tanning agent were added, preferably a chromium sulfate of a basicity of 33%.
Alternate resting and moving periods up to a about 12 hours of total treatment were carried out. Although the bath can further be used for the following steps it was removed and the process carried out further with a new bath.
f) A new bath for a common chromium tanning process with 9% chromium salt of 33% basicity was used which was basified in the usual manner. Then the skins were allowed to rest on trusses for 8 hours.
g) The skins were retanned with a blend of two syntans, both being condensation products of formalin with different organic acids, namely a blend of glutaraldehyde and a condensate of naphthaline disulphonic acid with formaldehyde.
Subsequently the leather was finished by usual and fat liquoring and mechanical treatment.
~267'7~3 The resulting leather had a certain similarity with reptile leather of about comparable strength but was pliable and flexible such as a fine leather for pursPs etc.
,. .
Claims (13)
1. A process for the preparation of leather from fish skin comprising the steps of:
(a)descaling the fish skins, prior to chemical modification, in a moving drum containing a first bath of at least one surface active member selected from the group consisting of anionic, non-ionic and amphoteric organic compounds and a combination thereof, said descaling preserving the scale pockets;
(b)treating the skins in a second bath containing a member selected from the group consisting of keratolytic enzyme, an alkali metal sulphide, an alkali metal hydrogen sulphide, lime and water and a combination thereof under stirring;
(c)degreasing the skins by means of the action of a surface active member selected from the group consisting of non-ionic compounds, anionic compounds, solvents and enzymes, and a combination thereof;
(d)pretanning the skins with a syntan at a temperature of below 20° C. and a pH of 5 to 8;
(e)pickling the skins in a bath containing acid and salt at a pH of 1.5 to 4; and (f)tanning the skins with a member selected from the group consisting of chromium tanning solu-tions, a syntan taning solution and a combination thereof .
(a)descaling the fish skins, prior to chemical modification, in a moving drum containing a first bath of at least one surface active member selected from the group consisting of anionic, non-ionic and amphoteric organic compounds and a combination thereof, said descaling preserving the scale pockets;
(b)treating the skins in a second bath containing a member selected from the group consisting of keratolytic enzyme, an alkali metal sulphide, an alkali metal hydrogen sulphide, lime and water and a combination thereof under stirring;
(c)degreasing the skins by means of the action of a surface active member selected from the group consisting of non-ionic compounds, anionic compounds, solvents and enzymes, and a combination thereof;
(d)pretanning the skins with a syntan at a temperature of below 20° C. and a pH of 5 to 8;
(e)pickling the skins in a bath containing acid and salt at a pH of 1.5 to 4; and (f)tanning the skins with a member selected from the group consisting of chromium tanning solu-tions, a syntan taning solution and a combination thereof .
2. A process as claimed in claim 1, wherein said group of surface active members further consists of a condensation product of alkylene oxide with C5- to C20- alkanol, a fatty sulphonate alcohol, a fatty sulphonate, a fatty-sulphate and a fatty alcohol-sulphate and a combination thereof.
3. A process as claimed in claim 1, wherein the pretanning step is carried out with a member selected from a group consisting of a condensation product of a monosulphonic acid, di-sulphonic acid, trisulphonic acid and formaldehyde and a combination thereof.
4. A process as claimed in claim 3, characterized in that the mono-, di- or trisulphonic acid is derived from a member selected from a group consisting of phenol, naphthaline and lignin and a combination thereof.
5. A process as claimed in claim 1, wherein the pretanning and tanning steps are carried out in the same bath.
6. A fish skin leather as prepared according to a process as claimed in claim 1.
7. A process as claimed in claim 1, further comprising the steps of:
resting the skins after tanning; and then washing and retanning the skins with a member selected from the group consisting of aluminium salts, chromium salts and syntans and a combination thereof.
resting the skins after tanning; and then washing and retanning the skins with a member selected from the group consisting of aluminium salts, chromium salts and syntans and a combination thereof.
8. A process as claimed in claim 7, further comprising the steps of:
liquoring the skins with fat after retanning;
dyeing the skins after said liquoring;
and the mechanically processing the skins.
liquoring the skins with fat after retanning;
dyeing the skins after said liquoring;
and the mechanically processing the skins.
9. A process as claimed in claim 1, further comprising:
immediately after treating said skins with said alkali metal sulphide, removing any sulphide remaining from the treatment in said second bath by adding a precipitating agent and washing the skins.
immediately after treating said skins with said alkali metal sulphide, removing any sulphide remaining from the treatment in said second bath by adding a precipitating agent and washing the skins.
10. A process as claimed in claim 1, wherein said degreasing step takes place in said second bath.
11. A process as claimed in claim 1, wherein said fish skins are descaled in said first bath for 15 to 60 minutes, treated in said second bath for 20 to 60 minutes, and wherein said degreasing step takes place for 20 to 30 minutes, and said pretanning step for 15 to 45 minutes and said pickeling step for 135 to 195 minutes.
12. A process as claimed in claim 1, wherein said degreasing step takes place in a separate bath.
13. A process as claimed in claim 1, further including the step of at least partially degreasing said fish skins in said first bath simultaneously with said descaling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000526836A CA1267753A (en) | 1987-01-07 | 1987-01-07 | Process for the preparation of fish skin |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000526836A CA1267753A (en) | 1987-01-07 | 1987-01-07 | Process for the preparation of fish skin |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1267753A true CA1267753A (en) | 1990-04-17 |
Family
ID=4134694
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000526836A Expired - Fee Related CA1267753A (en) | 1987-01-07 | 1987-01-07 | Process for the preparation of fish skin |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1267753A (en) |
-
1987
- 1987-01-07 CA CA000526836A patent/CA1267753A/en not_active Expired - Fee Related
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| Date | Code | Title | Description |
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| MKLA | Lapsed |