EP1045039A1 - Method for the preparation of leather from fish skin - Google Patents

Abstract

A process for the production of leather from fish skin uses undecomposed skin and involves (a) washing/degreasing with alcoh (b) descaling with enzymes, (c) alkaline digestion at not above 18 degrees C followed by decalcification and (d) tanning with sa solution plus organic acids and tanning agents, drying and lubricating with cationic agents.

Description

The invention relates to a method for producing leather from fish skin.

The purpose of the invention is the production of a fish leather, in which the natural Preserve structures, species-specific drawings and colors as far as possible stay.

A few years ago, leather made from reptile skin was very modern. The skins were mostly obtained from wild animals. This made some snake species almost eradicated, which has led to their protection status.

Due to the Washington Protection Convention, the import is numerous snake species or their skins are prohibited. Some types of snakes are propagated on farms. Nevertheless, the interest in snake leather is declined.

The fish form the most diverse group of the animal kingdom. There is more than 24,000 species of fish, a large number of which are either commercial fish the waters, namely from the sea, from lakes and rivers, caught or in Ponds are created for consumption. All of these fish species are not legal protected so that no problems with the natural and Animal welfare laws can arise. In addition, the raw material is currently Fish skin is not used intensively. The skin of the fish is either at the Preparation of food with recycled or disposed of as a waste product.

The skin of the individual fish species is structured very differently. The Scale pattern, scale size, drawings and colors are species-specific. Even if you only get fish leather from all large, useful fish would be an almost inexhaustible, wide range for the fashion industry different leathers with different drawings, different structures and different color variations available. If you count less, but species not protected by law, exclusive leather products can also be found on the Market. Protected and endangered fish species can in relation to the wide variety of unprotected fish species be careful.

The exclusivity of the fish leather is emphasized by the fact that every product is an original because every single specimen of a fish species shows certain individual differences. The authenticity of the fish leather product can with the sideline that no other family in the animal kingdom happens to be recognized with certainty.

That fish leather is currently neglected by the leather and fashion industry is due to the fact that the fish leather by previously known tanning methods is devalued. The scaly pockets are injured and the natural ones Structures such as coloring and species-specific drawing are destroyed. Moreover the fish-typical smell is not permanently removed.

The production of leather from fish skin is known from EP-B-0 285 738 and EP-A-0 575 632, as well as from US-A-4 379 708, 4 755 186 and 4 877 410. In the known methods of dried or salted skin, that is dead tissue, ran out, as is usual in the tannery. The Descaling is done mechanically. In addition, only with anionic fatliquors worked. In this leather production, the natural pigments destroyed and scaly pockets injured. The leather must then be colored with artificial colors when dressing, so that the species-specific Character of the fish leather as color and structure is destroyed.

The method according to the invention is intended to protect the natural structures of Fish skin, especially the color and drawing, remain undamaged. The The method according to the invention is characterized in that fresh or frozen fish skin used in this state, in which after the death of the Fischs has not used any decomposition, and the fish skin with the help of Alcohol washes and degreases, descaled with the help of enzymes, so far present intermediate product with the help of alkaline substances at a temperature skin digestion of no more than 18 ° C and then descaling, it using saline and adding organic acids and tanned from tannins and then faded and mostly with cationic Means greasy.

The inventive method for the production of fish leather with natural coloring and structure based on a preferred implementation on the production from fresh fish skin or on the preservation of the fish skin in the fresh state with shock freezing process, removal of meat, fat tissue and subcutaneous tissue (fleshing), washing and desquamation with the help of Enzymes and, if necessary, mechanical desquamation, skin disruption with alkaline substances and their removal by washing and so-called descaling, Acidification of the fish skin (pimples or conditioning), tanning and Greasing with a mixture of cationic and anionic greasing agents. It preferably also includes a new type of dressing with which the leather surface is treated so that the scales pockets when processing the Leather, e.g. B. when sewing products, do not solve, so can get up.

The following are examples of different variants of fish leather manufacture and described the related processes.

Only fresh fish skins are used for leather production. For later leather production, they are first used in the food industry frozen blast freeze. The skinned fish skins are packed in plastic bags and at a temperature of -30 ° C to -18 ° C frozen, the layer of fish skins intended for freezing should not exceed about 20 cm thick. The short-term storage of the Fish skin can then be done at a lower temperature (-3 ° C to -1 ° C).

Only the fish skins are suitable for further processing Process of autolysis, that is the natural process of self-digestion after Death of the organism, has not yet started. At this stage, when the If the patient is deadly rigid, the tissue is still countered by the body's own enzymes Protects bacteria and fungi and is also more resistant than dead tissue against the attack of the enzymes that occur during desquamation Invention are used.

On the basis of the invention it is possible to produce a fish leather in which the natural structures such as pigments and colors are largely preserved. Fresh or frozen and thawed fish skins are e.g. B. with the help of a Meat removal machine such as a meat removal cylinder with a working width of approx. 75 cm of muscle, fat and subcutaneous tissue. In the usual meat removal machines in the leather industry, consisting of a Pressure roller and a knife roller, the skins must be turned.

After fleshing, the fish skin is washed and degreased, thereby the smell of fish is eliminated. The wash solution is based on the weight of the fish skin from 200 to 300% water, 2 to 3% Supralan 80® (fatty alcohol ethoxylate) and / or 1 to 3% Supralan UF® (BASF AG) (fatty alcohol polyglycol ether) or 2 to 3% Baymol AN® (Bayer AG) (non-ionic emulsifier). The temperature should do not exceed 3 ° C. Duration about 30 minutes. In the above and The following percentages are based on the following scheme: 100 kg Fish skins correspond to 100%, 1% of the detergents, tannins, Salt, acids corresponds to 1 kg.

In the subsequent process, the fish skin is broken down with the help of the enzymes. 0.2 to 1.0% Oropon® (Röhm AG) (proteolytic enzymes based on pancreas) or the same amount Basozyme® (Bayer AG) (mixture of bacterial enzymes with descaling salts) used. The duration of the treatment is 20 to 90 minutes depending on the type of fish, e.g. B. Salmon 10 to 45 minutes, carp 20 to 75 minutes. The temperature of the Solution should be 33 ° C to 37 ° C and the pH between 7 and 9. The Fleet length 200 to 300%.

Some fish species have mechanical and enzymatic desquamation required. Before the actual tanning, the fish skins are removed with the help of open to alkaline substances. This is done with the help of a pre-washer (1 to 3% NaOH, liquor length 200% to 300%, duration 20 to 180 minutes) and one Post-scrubber (4% CaOH, liquor length 200% to 300%, duration 24 to 120 hours). The temperature of the liquor must not exceed 18 ° C in both processes. The preferred temperature is 15 ° C.

Three methods are used for descaling. The first method: Extensive rinsing with water when the skins are constantly moving.

Second method: treatment with organic acids, such as vinegar or Formic acid, titration in small doses until a pH of 6.0 is stabilized. Fleet length 200 to 300%, duration 3 to 4 hours.

Third method: treatment with acidic salts of multivalent aromatic Acids, e.g. B. Decaltal N® (BASF AG), adding in small doses until the pH is stabilized at 6.0. Fleet length 200 to 300%, duration 12 hours, e.g. B. about Night.

The fish skins are pickled for optimal absorption of the tannins (acidified). Before that, the fish skins are soaked in a solution for 15 to 60 minutes, consisting of 200 to 300% water and 60 to 100 g NaCl per liter, (equivalent of at least 6 B). After this time, the solution becomes organic Acids such as formic acid and acetic acid diluted 1:10 are added until a pH the solution from 3.0 to 4.0 is achieved. The pimple time depends on Fish species up to 48 hours.

After this time, the fish skins are ready for the real one Tanning. It consists of the addition of mineral tannins, such as chrome or aluminum solutions, vegetable tanning solutions like Mimosa, Valonea, Chestnut extracts etc., synthetic tanning agents, phenol, aldehyde, resin and Combination tannins.

In the case of chrome tanning, the chemicals are preferably added successively to the pickling liquor, the pH of which is 3.0 to 4.0: 1 to 2% aluminum tanning agent, namely Al ₂ 0 ₃ .3H ₂ 0 aluminum hydroxide, e.g. B. Novaltan AL® (Zschimmer & Schwarz GmbH) or Lutan BN® (BASF AG). This is followed by 7% chromium tanning agent, namely Cr0 ₂ , e.g. B. Chromitan B® (BASF AG) or a chromium sulfate known as Chromosal B® (Bayer AG) and / or 1 to 4% combination tanning agent chromium-syntan, e.g. B. Basyntan CN® (BASF AG). One hour before the end of the tanning, 1% Implenal AP® (BASF AG), a mixture of dicarboxylic acid salts, is added. The entire tanning process takes 24 hours.

Tanned leather is dulled with the help of 1 to 3% NaHCO ₃ (sodium hydrogen carbonate) or 2 to 3% NaHC00 (sodium formate), wilted and left for approx. 12 to 48 hours, e.g. B. overnight on the goat. Afterwards the leather is dulled again to a pH of 3.8 to 4.0, wilted and greased with the help of a hammer grease gun. A mixture of 15% Lipamin Licker SO® (BASF AG), a cationic fatliquor, and 5% Pelgrassol SF® (Zschimmer & Schwarz GmbH), an anionic fatliquor, is used for fatliquoring.

Dried leather is stolled, i.e. softened, and can be used in it Condition can be used immediately. For certain purposes, it will be used after Stollen prepared. When dressing, there are several on the leather surface Lacquer coats applied. The first layer - the base layer - is applied that the paint, e.g. B. a mixture of 200 parts of Astacin-Grund UH® (BASF AG), an anionic polyurethane dispersion, + 780 parts water + 20 parts Astacin Finish PUM®, an anionic polyester-polyurethane dispersion, (BASF AG), into the shed pockets. The paint is brushed against plotted the direction of the scales, after which the scales pockets in reverse Direction are smoothed again. After drying the base layer, two Binding layers applied, the first in the same way as the base layer Using a brush, and the second is done after repeated drying using a Spray device applied. The binding layers are e.g. B. a mixture of 100 Parts of Lepton Binder SD®, an acrylic-based copolymer, + 450 parts of water + Corial Grund OHN®, a polyacrylate dispersion + 100 parts Astacin Finish PUM® (BASF AG), an aqueous anionic polyacrylate dispersion.

After each lacquer application, the leather is dried and then the dried leather is ironed at a temperature of 50 to 80 ° C. at a pressure of 20 · 10 ⁶ Pa (200 bar) for 3 to 10 seconds in an ironing press. The components of time, pressure and temperature are matched to one another depending on the desired leather quality, with less of one of the components being able to be compensated to a certain extent by more of another of the components. So you can z. B. increase two of these components and decrease one to achieve the same result. The optimal values of the components depend on the respective fish.

Subsequently, two cover layers are applied to the binding layers with the help applied to a sprayer and ironed again. For a matt surface z. B. a mixture of 500 parts of Astacin Mattierung MT®, an aqueous anionic dispersion of an acrylic polymer and polyester urethane, + 490 parts Water + 20 parts of Astacin Finish PUM® (BASF AF), an aqueous anionic Polyester-polyurethane dispersion, and for a shiny surface e.g. B. a Mixture with Astacin Top LB®, a dispersion of 500 parts of an aliphatic Polyurethane and the same amount of other additives in matt painting used.

As described under the chrome tanning, the lacquered leather - like described below - retanned:

200 to 300% water are added 20 g / l sodium chloride and 6 to 10 % white tannin containing phenol, e.g. B. Basyntan DLX® (BASF AG) in 3 to 4 servings, depending on the 30 minutes. The pH of the liquor is 3.8 and the tanning time is 8 to 12 hours. Then wilting and processing, as with the mineral Tanning described. This tanning method creates a white leather with light bluish tone. It corresponds to the natural color of the salmon and has that Quality of the gallantry leather.

In order to achieve the quality of a shoe upper leather, is at a pH from 3.6 to 3.8 gluten dialdehyde, e.g. B. Relugan GT 50® (BASF AG), directly into the Fleet of white tannins, e.g. B. from phenol-containing tannin added. The Leather gets a slightly yellowish tone, especially along the sideline is made clear. The leather becomes fuller, but loses speed.

Some people want leather on the market that is made with vegetable Tannins have been tanned. Below are two examples for completeness listed:

Leather that had previously been pickled is dulled to a pH of 4.3 to 4.5. The liquor length is 200 to 300%, it contains 30 to 60 g / l sodium chloride and 2% phenol-containing tanning agent, e.g. B. Basyntan N® (BASF AG), in three doses each Added 30 minutes. This is followed by 7% vegetable tanning agent; e.g. B. gives Mimosa a leather dyed pink, quebracho a reddish tinge, sumac an ivory color, Tara a white color, Valonea a brown color. The herbal Tannin is added in four doses, two hours in a row. The tanning time is about 12 hours, e.g. B. overnight. The pH value of the leather is about 4.0 set to 4.5, then slightly rinsed, wilted and further processed, e.g. B. greased, dried, rolled and trimmed.

Alternatively, mineral-pretanned leather with vegetable substances be retanned. Leather dulled to a pH of 4.0 to 4.3 implemented in a new fleet with a pH of 4.3 to 4.5. The fleet length is 200 to 300%, 30 to 60 g / l sodium chloride are dissolved in this liquor and 7% vegetable tanning agent in four doses of two hours each. The tanning time is about 12 hours, e.g. B. overnight, whereupon the leather as described above is processed, e.g. B. greased, dried, rolled and trimmed becomes. This is how gallantry leather is produced. Becomes a shoe upper desired, after tanning with vegetable tanning agents, the leather can be used without Flushing after wilting in a new fleet can be tanned as follows:

Fleet length 200 to 300%, 20 to 60 g / l sodium chloride and 6% combination tanning agent chrome-sytan, e.g. B. Basyntan CD® (BASF AG) in four Cans of 30 minutes in a row. The tanning time is 8 to 12 hours, e.g. B. over night.

The tanning described above represents general parameters, ie Basic tanning, through special controls of the tanning process and the subsequent dressing can be more specific as needed and desired Types of leather are produced. With the present tanning process, e.g. B. Upholstery leather, gallantry leather (soft and fine leather), upper shoe leather or clothing leather be generated.

Claims (13)

Process for the production of leather from fish skin,
characterized in that fish skin is used in which no decomposition has started after the death of the fish, and a) washes and degreases the fish skin with the help of alcohols, b) descaling with the help of enzymes, c) by means of alkaline substances, at the temperature of not more than 18 ° C., the skin is disrupted and then descaled, d) it is tanned using saline and with the addition of organic acids and tannins and then wilted and mainly greased with cationic agents. Process according to Claim 1, characterized in that the fresh, de-skinned fish skins by shock freezing at the stage of rigor mortis preventing the start of autolysis of the fish skin tissues preserved and kept in stock in the frozen state, only for later Start thawing with step a). A method according to claim 1 or 2, characterized in that the Wash and degrease the fish skin with a 1 to 3% solution of the alcohols by eliminating the smell typical of fish skin. Method according to one of claims 1 to 3, characterized in that one after the desquamation of the fish skin with the help of the enzymes if necessary then performs a mechanical descaling. Method according to one of claims 1 to 4, characterized in that to open the skin with the help of a pre-scrubber with a 1 to 3% solution of Na0H for 20 to 180 minutes and with a post-treatment with a 4% solution of Ca0H for 24 to 120 hours, the Liquor length of both limingers is 200 to 300% and the temperature of the Solution is preferably between 14 ° C and 16 ° C, and the fish skin washed with water and titrated with organic acids pH decalcified from 6.0. Method according to one of claims 1 to 5, characterized in that to tan the fish skin, the saline solution with a liquor length of 200 to 300% with addition of 60 to 100 g NaCl = equivalent to at least 6 B. applies and the organic acids by titration to a pH of 3.0 to 4.0, preferably 3.5. A method according to claim 6, characterized in that for tanning mineral, vegetable, phenolic, resin, aldehyde and combination tanning agents starts. A method according to claim 6, characterized in that for tanning mineral solutions of chrome or aluminum tannins or of Combination tannins and aldehyde tannins are added. A method according to claim 8, characterized in that the pre-tanned Leather into a new fleet consisting of phenolic white tannins, where aldehydes are added to the liquor if necessary. Method according to one of claims 1 to 9, characterized in that the wilted leather with a mixture of cationic and anionic Medium greases, namely preferably with a mixture of 15%, of Weight of wilted leather, one cationic and 5% one anionic agent. Method according to one of claims 1 to 10, characterized in that the leather surface after withering and greasing and after one Dehydration and cleats prepared. A method according to claim 11, characterized in that the leather surface to prevent the scales pockets from following Processing stand up, painted and then with one base coat, two Binder layers and two outer layers consisting of water-soluble Paint emulsions, and coats these layers at a temperature of 50 welded up to 80 ° C in an ironing press. A method according to claim 12, characterized in that the layers are applied to the leather surface as follows: a) an aqueous solution of anionic polyarethane dispersion and anionic polyester-polyurethane dispersion is applied as the base layer; b) after the base layer has dried out, the two binder layers, consisting of a mixture of an acrylic-based copolymer, a polyacrylate dispersion and an aqueous anionic polyester-polyurethane dispersion, are applied; c) after the two binder layers have dried, the leather present to that extent is ironed and covered with the two outer layers by applying an aqueous solution of anionic dispersion of an acrylic polymer and polyester urethane with aqueous anionic polyester-polyurethane dispersion and repeatedly welding to the binder layer by ironing.