HU203907B - Process for afterliming unhaied fells and splits - Google Patents

Abstract

The process described is carried out with an aqueous alkaline liquor containing formanidine sulfinic acid (thiourea dioxide) in combination with calcium hydroxide and/or alkalis and, if necessary, swelling inhibitors.

Description

FIELD OF THE INVENTION The present invention relates to a method of post-masonry of leeches and slit skins by applying an aqueous-alkaline bath, to which formamidine sulfinic acid is added in combination with calcium hydroxide and / or alkalis, optionally with anti-swelling agents and optionally one or more reducing sulfur compounds.

Hides and furs are sometimes known as "skins" after the animal has been slaughtered. is immediately processed in the form of green hides in tanneries. Usually, however, they are first preserved by adding salt or disinfectants to prevent decay. Salted and dried hides are soaked in dirt, manure, salt and preservatives by soaking in tanneries and restoring their original water content.

Thereafter, a depilation procedure is applied which is adapted to the desired skin quality and retention or destruction of the hair.

In the case of valuable hair or wool, the skin is decalcified on the flesh side by applying lime-sodium sulfide pulp to the flesh of the skin. Particularly to obtain a smooth bark coat (surface) and on very sensitive skin, for example, calf bumps apply lime paste to the hairy side. In such a liming procedure, post-mashing is usually required to achieve skin opening.

The most commonly used methods are calcareous barrels, in which the hair is completely destroyed or loosened so that it can be easily mechanically removed by mechanical means. In lime, combinations of sodium sulfide / sodium bisulfide and lime in aqueous solution are used. Other liming processes include sodium chlorite (U.S. Patent No. 1,276,286) or mixtures of organic nitrogen or sulfur compounds such as dimethylamine, dimethylamine sulfate, 1,3-diaminopropane, 2-amino-2-methyl- propanol and / or N-methylaminoethanol, ethanolamine, diethanolamine, n-butylamine, triethylamine, dibutylamine, urea, formamide, dimethylformamide, acrylic and methacrylamide compounds, isothiouronium compounds , hydrazine, ethanethiol, propanethiol, thioglycolic acid and its salts, thiourea dioxide and cysteine hydrochloride (U.S. Patent Nos. 23 01 591; 20 53 016; and 33 32 748 and Austrian Patent 381 952).

Fungal or bacterial proteinases, or combinations of these proteinases with amines or amine cleavage compounds and optionally reducing sulfur organic compounds, are used for enzymatic hair removal and depilation (German Patent Publication No. 34 29 047).

Modem methods for retaining the waste water load and for maintaining the hair and providing sulfide-free or sulfide-free conditions are known.

In the case of classical hair preservative liming using 0.5% sodium sulfide and lime, carried out overnight in barrels or mixers, the hair can be separated into an easily filterable mass2. In the Sirolime process, most of the hair falls out and can be separated and filtered with a suitable rinse aid. In the Darmstadt procedure, the Reutlinger vaccination procedure and the lactic procedure, the hair must be mechanically removed after chemical exposure. This material can be sold as fertilizer and does not burden soldering equipment in its dissolved form.

Excessive swelling of the skin can occur in any liming procedure, which reduces the effectiveness of hair removal. By swelling, the roots of the hair are closed and so are not affected by liming chemicals. In addition to the hair and wool, the epidermis (cornea), the corneal layer, the thoracic layer and the basal layer must also be removed. Therefore, more recent descriptions use a division of hair removal (liming) and skin revealing (postmortem) (see Leder- und Hautemarkt, Vol. 30, Vol. 38, page 14, October 24, 1986), in which most of the cuts and splitting operation is also included.

After the hair-preserving liming processes, oxidation liming and enzymatic processes, the so-called postmortem is needed. In the aftermath, the skin's fiber structure (collagen) must swell and prepare the skin to absorb tanning substances. The purpose of post-masonry and liming is therefore quite the opposite. While in limescale and liming processes chemicals only have to be applied to the surface, in the afterglow they need to penetrate inside the hides. This specific process of post-littering (main excavation) must necessarily be carried out, for example, in the processing of hides and skins of hides or skins and in the manufacture of greasy tanned garments, gloves or linings. Post-masonry is usually performed as pure liming with calcium hydroxide (lime hydrate) and slaked lime (lime pulp). Addition of reducing agents, such as sodium sulfide or sodium hydrogen sulfide, loosens the hair roots and hairs. Undesirable proteins that adversely affect skin quality should be removed. Unwanted proteins include albumin, globulins, melanins, keratins, procollagen, tropocollagen, and mucopolysaccharides, which are referred to in the technical term as "pisocene."

One of the major problems associated with hair removal is insufficient hair loosening, which sometimes results in hair roots and hairs remaining in the leeks after liming. These cause imprints on the upper of the shoe, such as rough surfaces, uneven staining, and unevenness in the topcoat. Incomplete removal of 'dirt' results in uneven tanning and irregular staining. When sulphide is added to the postmortem, a "black stain" is created, as black sulphide precipitates upon contact with iron or copper. They can only be removed from the skin again with difficulty and considerable financial effort.

Therefore, the challenge was to develop a system for post-mascara that results in the complete removal of base hairs and "dirt", while avoiding the disadvantages of using sulfides and the degradation of skin.

HU 203 907 Β

It has now been found that surprising and unexpected effects in the aftertreatment agent can be achieved by using 0.1 to 1.0%, preferably 0.2 to 0.5% by weight of formamidine sulfamic acid in the aqueous-basic bath according to the invention. in combination with calcium hydroxide and / or alkalis, optionally in the presence of anti-swelling agents and optionally one or more reducing sulfur compounds.

The resulting leeks are completely free of "dirt, have a very fine and compact bark coat and have an unusual brightness. In addition to at least partially preventing sulfide formation and thereby significantly reducing the environmental load, it was not foreseeable that, above all, the lighter color of the leeches could be enhanced in the prodrug.

Light lenses are very sought after, because the color tones are more uniform and shine with poorly covering paints and dyed skin. Therefore, after tanning, the skin is sometimes subjected to oxidative bleaching with potassium permanganate / sodium bisulfite or hydrogen peroxide or sodium chlorite. It is also common to bleach with hydrosulphite, sodium dithionite, hydroxymethane sulphinic acid, possibly in combination with optical brighteners. In any case, the combination of the invention can be used to eliminate bleaching and thus save an additional processing operation. It was not foreseeable that the addition of formamidine sulfinic acid to the post-opener would avoid the otherwise necessary processing and, as described in German Patent Publication No. 36 15 816, an increase in brightness could be achieved.

After the soaking and liming of the skins and fur, the process of the present invention is carried out. Normal operating operations such as chopping, cleaving, trimming can also be performed.

The optimum effect for the treatment of lichen or split skin is achieved when the pH range of the bath is 8.013.0, preferably 9.5-12.0. The pH is usually self-adjusting when the leeches or slit skins are re-immersed in water after flesh and cleavage, as a result of which chemical residues in the skin diffuse into the water; calcium hydroxide may also be used to adjust the pH. However, the pH is known per se in the form of caustic soda, caustic soda, magnesium hydroxide, sodium carbonate (soda) or amines or amine cleavers such as dimethylamine, dimethylamine sulfate, 1,3-diaminopropane, it can also be adjusted by adding amino-2-methylpropanol, N-methylaminoethanol, ethanolamine, diethanolamine, n-butylamine, triethylamine, dibutylamine or hydrazine.

Other talented hardness reducing agents include salts such as sodium chloride or calcium chloride, potassium rhodanide, potassium oxalate, potassium hydrogen tartrate, or urea, formamide, dimethylformamide, acrylic and methacrylamide, glycols and dioxane. .

The amount of water used in the postmortem of the present invention is generally about 100-500% by weight of the lumps or slit skins inserted and can be varied within wide limits without limiting the benefits of the present invention.

The process of the present invention takes from 2 to 24 hours, and in special cases several days for pigskin and tanned hides.

The calcium hydroxide is used in an amount of 0.1-5.0% by weight, preferably 0.52% by weight. Calcium hydroxide loosens the structure of collagen by alkaline swelling and dissolves non-collagen proteins. This opens up the skin. The amount of calcium hydroxide is determined primarily by the preventive liming and skin breakdown achieved and secondly by the desired skin type (upper, lining, sole, saddle, upholstery, bag, cloth, belt or glove).

The duration of exposure to the post-mascara according to the invention, similar to the amount of calcium hydroxide, is adapted to the desired skin type. Longer exposure times and higher amounts of calcium hydroxide result in essentially better skin healing and softer skin.

The following examples illustrate the process of the invention without limiting the scope of the invention.

Example 1

Production of calf box aniline leather

Raw materials: calfskin, black blotch,

Weight class 8-12 kg

Digging weight: 600 kg - 60 pieces

The skins are soaked in the usual way to remove "dirt". For liming, sodium sulfide is pre-dissolved in warm water and adjusted to 1.08 g / cm ³ by addition of lime hydrate and kaolin. This lime pulp is applied to the meat side of the calfskin. After 5 hours, the hairs become so loose that they can easily be scraped off.

The main mass is then carried out in barrels with 1.3% sodium bisulfide.

The leeks are very smooth and still have roots on the surface. The pigmentation is still visible. Post-spreading is done as follows: Post-spreading (barrel):

2501% water, 27 'C 2.01% lime hydrate (white lime)

0.51% formamidine sulfinic acid 0.21% sodium hydroxide (50%).

Move for 2 minutes at 2 turns per minute for shuffling. The treatment time is 10 hours. During this time, we move it for 5 minutes every hour. The pH of the bath is 12.0. The t% data refers to the soak mass.

After treatment, the bath is lowered and the leeks rinsed with 2501% water (27 'C).

The sweat swells smoothly, completely free of "dirt", very clean. No pigmentation and no root can be detected. The bark layer is dense and knit.

Further processing into aniline calf skin can be carried out in the usual manner. Finished skins stand out with a perfectly even coloring and high shade of color. After the aniline preparation, the structure of the skin surface (barricade) is fine, tightly closed.

HU 203 907 Β

Example 2

· Deer

Manufacture from oily tanned leather

Commodity: Deer, New Zealand

Digging weight: 440 kg - 55 pieces

The raw material is soaked in the usual way and lime-barreled. After liming, the meat is minced and the bark layer cut off. For perfectly even skin exploration, we perform the following post-massage in the trap:

4001% water, 25 'C 0.4% formamidine sulfinic acid 2.5% lime hydrate.

The usual addition of 0.5% sodium sulfide is omitted. The pH of the bath is 10.5. After 4 days of treatment, the leeks are removed from the trap. The leeks are yellowish-white and slightly swollen. After fleshing and peeling off the bark layer, the impressions of the ribbed cylinder are no longer visible. All further processing operations can be performed without any changes. Finished, chamois tanned skins are soft, pleasant to the touch and definitely lighter than conventionally tanned skins.

Example 3

Production of sheepskin

Raw materials: short hair New Zealand sheepskin, salted

Weight: 240 kg - 80 pieces

Soaking is done in the usual way. The meat is then fattened and depilated with sodium sulfide in lime. The depilated skin is very smooth, sometimes with clumps of adherent hair and gray-green in color. For skin exploration, we place them in the following follow-up fabricator:

Aftermath (barrel):

5001% water

0.61% formamidine sulfinic acid 0.21% sodium hydroxide (50%)

11% Sodium Chloride 151% Lime Hydrate.

Bath pH 115 · Treatment time 24 hours. Meanwhile, the barrels are moved for 5 minutes per hour. After rehydration, the leeks were slightly swollen and not collapsed; autoclaving refers to a thorough degradation of the skin. The skins do not contain hair roots and hairs. They are completely free of "dirt". The barrel is smooth, tightly closed and flexible. Further processing is carried out in the usual way. Due to the light color of the leeks, potassium permanganate / sodium bisulfite oxidizing bleaching can be omitted after tanning. The skins are soft, completely wrinkle-free and light. The surface has a very fine pore and a dense tail.

Example 4

Herbal tanned leather

Raw materials: ox leather, black blotch, Ireland

Weight class: 40-49.5 kg

Digging weight: 570 kg - 13 pieces

Soaking and descaling are performed in the usual manner. Then we rinse, fry and split. There are many hair roots found in wrinkles. The pigmentation ("dirt") is clearly visible. After cleaving, the beaver slices are placed in the following aftermaker:

Barrel:

2001% water, 25 'C 1.81% lime hydrate (white lime)

051% formamidine sulfinic acid 0.3% calcined soda 0.21% dimethylamine sulfate.

The pH of the bath is 125 · The treatment time is 3 hours, 15 minutes per hour, 5 turns per minute. Finally, the bath is lowered and the slit skins processed in the usual way.

Postmortem removed the root of hair completely. Slit skins are shiny, free of bark protrusion, and very light Pigmented areas and "dirt" are no longer detectable. A large variety of leather varieties is available for the production of vegetable tanning hides.

Further processing operations may be carried out in the usual manner.

Mimosa tanned skins are very light, even, pale pink, and have a close-fitting coat. The skin is firm, firm and firm.

Example 5

Production of bovine leather

Raw material: bullskin, black blotch

Weight class: 40-495 kg

Soaking weight: 98 kg, 2 pieces of meat and mutton

The crude product is soaked in the usual manner and lime is leached in a sulfide-poor liming system consisting of a mixture of organic reducing compounds (2%), lime hydrate (5%) and (0.8%) sodium bisulfide.

After chilling and slicing, place the meat and couscous slices of the 2 straws removed from the produce in the following liming mill:

(a) barrel:

2001% Water, 30'C 051% Lime Hydrate 0.31% Formamidine Sulfinic Acid 0.11% Sodium Alkaline (50%)

0.21% mercaptoacetic acid sodium (thioglycolic acid sodium)

The pH of the bath is 9.5. The bath was moved for 15 minutes to mix chemicals and split skin. The barrel is then rotated automatically for 5 minutes at 10 revolutions per minute. The total treatment time in the aftermath is 10 hours.

For the other bark splits, we perform the following reworking:

(b) barrel:

2001% Water, 30 'C 0.5% Lime Hydrate 0.21% Sodium Hydrogen Sulphide 0.21% Mercaptoacetic Acid Sodium (Thioglycolic Acid Sodium)

The pH of the bath is 11.0. The duration of the postmortem is 10 hours. The bath is moved for 5 minutes every hour.

HU 203 907 Β

Comparison of the slit skin shows that in the postmortem of the present invention, the slit is very clear, completely free of "dirt, hair roots and fine hairs." The usual post-wound split hides are dark, filter green, and come in contact with 5 iron to produce black spots. Occasionally they contain immunized fine hairs.

The effluent used in the exemplary part (a) of this example is sulfide-free and can be neutralized without the release of an odorous hydrogen sulfide. Further processing shows that post-warped split hides according to part (a) are clearly lighter both in "wet-blue" condition and as finished hides. The staining is smoother and brighter. There is no difference between chemical (ash, chromium content, fat) and physical (strength, water uptake, 15 etc.) values.

Claims (2)

PATIENT INDIVIDUAL POINTS 1. A method for post-pulping post-depilatory larvae or splinters with calcium hydroxide and / or alkali, characterized in that the skin or slit skin is treated with an aqueous alkaline bath at pH 8-13, which is 0.1 to 1% by weight of formamidine based on the weight of the skin or slit. sulfinic acid optionally containing anti-swelling agents, preferably organic amines such as dimethylamine sulfate and optionally one or more reducing sulfur compounds such as sodium ammonium or calcium sulfide or a thiol such as thioglycolic acid or salts thereof. 2. A process according to claim 1, wherein the alkali is sodium hydroxide, caustic soda, potassium salt, magnesium hydroxide or soda.