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
  • C14C3/00—Tanning; Compositions for tanning
  • C14C3/02—Chemical tanning
  • C14C3/28—Multi-step processes
• • 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
  • C14C3/00—Tanning; Compositions for tanning
  • C14C3/02—Chemical tanning
  • C14C3/08—Chemical tanning by organic agents
  • C14C3/22—Chemical tanning by organic agents using polymerisation products

Definitions

• the main tanning with mineral tanning agents alone is not sufficient to give finished leather the required variety of properties.
• a retanning is connected to the main tanning.
• the leather producers still have to consider considerable environmental requirements.
• One of the main requirements relates to chromium in the wastewater, which is introduced into the wastewater through a main mineral tanning process with various chrome tanning agents.
• Many factories are therefore required to either have the main tanning section carried out by those companies that have the option of recovering chromium from the residual tanning liquor or to process the chrome-tanned wetbLue merchandise on the market.
• problems of this type have not yet been completely solved, since astonishingly much, too much chromium is still transferred from the leather into the waste water during further processing of this product.
• DE-OS 27 55 087 describes pre-tanning of raw material, with concentrations of 0.13 g Cr 2 O 3 / L, 0.18 g Cr 2 O 3 / L or 0 at the end of the tanning by means of polymers made from monomers containing carboxyl groups , 3 g of Cr 2 O 3 / L remaining liquor can be reached. These polymers are also suitable for retanning.
• DE-OS 31 41 496 A CopoLymerisate of PoLyacryLamid and MethacryLamid with cationic groupings in retanning are recommended, whereby coloring effects are in the foreground, but which do not cause any abnormal chromium fixation.
• polymer tanning agents often recommend that the leather be rinsed before retanning, which, however, leads to pollution of the wastewater by chromium which has not been sufficiently fixed beforehand.
• Other types of polymer tanning agents are sensitive to acid and form precipitates, so that the chrome leather must also be neutralized before use, which, depending on the neutralizing agent used, causes particularly high concentrations of chromium in the waste water.
• the outer aspect plays a major role in achieving leather properties.
• leather with the brightest possible color is sought in order to be able to dye very pastel or clear shades in the first place.
• the same requirements apply to leather that has been dyed dry and then kept in stock and then in stock - opffärbung be colored by means of a so-called K - depending on the requirement fashion.
• K - so-called opffärbung
• polymer tanning agents can generally be described in terms of leather properties in such a way that the leather treated with them is soft and more or less full and full-grain.
• the polymer tanning agents designated as firm-graining it must be established that the term "firm-grained” is relatively stretchy and does not come up to the usual level of with specially designed auxiliary agents, e.g. on leather treated with polyphosphates.
• polyphosphates have a coloring disadvantage in the case of very clear colors, since the leather is given a greenish basic color and thus introduces parts of achromatic color in the complementary area.
• polyphosphates cannot achieve the very high levels of exhaustion required.
• the present invention has therefore set itself the task of creating a retanning process for mineral-tanned, in particular chrome-tanned leather, which i.a. leads to a very high brightness of the leather as well as to a very low pollution of the waste water. This problem is solved with the features set out in the patent claims.
• chromium polymer polymer complexes doped with chromium that are used here are new; they can be produced in an inventive manner by the manner also characterized in the claims.
• auxiliaries were found in the complexes of polymer compounds with trivalent chromium claimed according to the invention, with which chromium exhaustions far beyond the prior art were achieved with simultaneous retanning, although chromium was additionally introduced into the retanning system.
• the leathers treated with the polymer complexes according to the invention are unusually pitted and at the same time maintain softness, an improvement over the prior art has also been achieved here.
• Another advantage that should not be underestimated is the characteristic, very bright basic color, which goes far beyond the usual level.
• the polymer complexes according to the invention are insensitive to acids and exchange undesired acid residues in the leather, so that the neutralization step in the conventional sense can also be dispensed with. Alkaline additives are still possible, they serve to set a desired pH range.
• the polymer complexes according to the invention improve the scar strength, particularly in the loose skin regions.
• the yellow tint characteristic of leather tanned with aluminum can be compensated very well.
• the polymer compounds can be prepared in a manner known per se (see, for example, E. Müller, Houben-Weyt, Methods of Organic Chemistry, Volume XIV-I 1961, p.1010-1080 and Volume XIV-II, 1963, p. 631- 633 and 705-713).
• the K values according to Fikentscher are between 5 and 120, preferably between 10 and 50.
• the polymer compound as an aqueous solution is from 1 to 80% based on active ingredient (see above), preferably between 5 and 60X and particularly preferably between 10 and 40% before.
• the doping ratio i.e. the ratio of polymer component to chromium content
• the doping ratio i.e. the ratio of polymer component to chromium content
• chromium compounds are generally understood to mean the soluble chromium-III compounds capable of complexation, even if chromium-VI compounds were applied, which were reduced to chromium-III compounds for the purpose of complexation in the mixture with polymers.
• Preferred substances for the polymerisation or polycondensation for the production of the polymers and / or copolymers claimed according to the invention are so-called monomer substances, such as e.g. Acrylic acid and / or methacrylic acid and / or maleic acid and / or their hydroxy compounds, which can also be present in the form of fully or partially neutralized salts.
• the preferred doping ratio of chromium to carboxyl groups of the polymers is between 1: 500 and 1: 1, preferably between 1: 100 and 1: 3 and in particular between 1:50 and 1: 5, the polymeric K values according to Fikentscher between 5 and 120, preferably between 10 and 50.
• the retanning process itself is not critical in itself.
• the leather piece is added, with the necessary amount of water, and previous rinsing can be dispensed with, and the complex solution is added and the drum is tumbled.
• E value the frequency of the E-value
• the resulting relative number states that a surface the higher the number of the E-value, the more helper it is.
• White BaSO 4 powder for example, has a value of 100. Pieces of leather that reach or even exceed 60 can be described as exceptionally bright.
• a wet blue piece was introduced without rinsing into a float of 300% water at 45 ° C. together with 4% of a commercially available, 33 percent aqueous sodium polyacrylate solution and drummed in a tanning drum for 1 hour. This neutralization fleet was drained and the chromium content was determined.
• the leather piece was rinsed, treated with a standardized amount of 7X of a mixture of commercially available licker for this series and finished. The result was a very soft, not very firm-grained, moderately filled, but little brightened leather. Chromium content of the remaining liquor: 100 mg Cr 2 O 3 / L E value of the finished leather: 53.5.
• Example 2 Under the same conditions as in Example 1, a wetbLue piece was treated with 5X of a 25 percent solution of a commercially available polymer product based on PoLyacryLamide instead of the sodium polyacrylate solution and finished. The result was a less soft, moderately filled, dark leather with moderate firm grain. Chromium content of the remaining liquor: 199.6 m g Cr 2 O 3 / L E value of the finished leather: 51.3.
• a wet blue leather cloth was treated with 300% water at 45 ° C. and 5% above complex solution without rinsing and drummed in a tanning drum for 1 hour. After the addition of 1% solid sodium bicarbonate and a milling time of 15 minutes, 7% licker mixture, Chandel's customary, water-emulsified fatliquor for leather) and another 1% sodium bicarbonate were added and the fabric was drummed for a further 45 minutes.
• the finished leather was soft, firm-grained than in example 1 and of a very light color. Chromium content of the compact remaining liquor: 10.1 mg Cr 2 O 3 / L E value of the finished leather: 60.3
• a piece of wetbLue leather was mixed without prior rinsing with 300% water at 45 ° C. and 5% of the above complex solution and drummed for one hour in a tanning drum. Thereafter, 0.9X sodium bicarbonate was added, the process was continued for 15 minutes and another 0.6% of sodium bicarbonate was added together with 7% of a licker mixture and the process was continued for 45 minutes. The result was a soft, light, filled and well-grained leather. Chromium content of the remaining liquor: 35.5 mg Cr 2 O 3 / L E value of the finished leather: 61.4.
• a 5% paste and 300% water at 45 ° C. were added to a wet blue piece without rinsing beforehand, and drummed in a tanning drum for 1 hour. Then 0.8% sodium bicarbonate was added, drummed for 15 minutes, 7% of a licker mixture and 1% sodium bicarbonate was added. After 45 minutes of flexing, the leather piece was finished as before. The result was a firmer, but still soft, light leather with very good firm grain. Chromium content of the remaining liquor: 8.9 mg Cr 2 O 3 / L E value of the finished leather: 59.6.
• Example 5 A wet blue piece was treated exactly as in Example 5 with a 5 percent complex solution. The result was a slightly softer, light leather with still good firm grain. Chromium content of the remaining liquor: 11.4 mg Cr 2 O 3 / L E value of the finished leather: 60.4.
• a 32 percent polymethacrylic acid with a K value according to Fikentscher of approx. 20 was produced from a monomer fraction of 90X acrylic acid and 10X methacrylic acid and neutralized to pH 7.5 with sodium hydroxide solution. 2000 g of this neutralized polymethacrylic acid were mixed with a solution of 63.7 g of 33% basic chromium sulfate and heated to 80 ° C. The result was a complex solution with good fluidity.
• a wetblue piece was mixed without prior rinsing with 300% water at 45 ° C. and 5% solution above and drummed in a tanning drum for 1 hour. The fleet was then drained and checked for chromium. The leather piece was washed in 200% water at 60 ° C for 10 minutes of flexing. In a new fleet of 200% water at 60 ° C, 7% licker mixture was added, drummed for 20 minutes and the fat substances of the licker fixed with 0.5% formic acid for 45 minutes.
• the finished leather was soft, FULL, astonishingly pitted and exceptionally bright. Chromium content of the remaining liquor: 60.8 m g Cr 2 O 3 / L E value of the finished leather: 63.6.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Treatment And Processing Of Natural Fur Or Leather (AREA)

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• 1984
  • 1984-02-25 DE DE3406912A patent/DE3406912C1/de not_active Expired
  • 1984-12-11 ES ES538491A patent/ES8600775A1/es not_active Expired
• 1985
  • 1985-01-14 PT PT79827A patent/PT79827B/pt unknown
  • 1985-01-30 BR BR8500409A patent/BR8500409A/pt not_active IP Right Cessation
  • 1985-02-18 JP JP60028526A patent/JPS60190499A/ja active Pending
  • 1985-02-20 US US06/703,551 patent/US4750906A/en not_active Expired - Lifetime
  • 1985-02-25 FI FI850768A patent/FI79143C/fi not_active IP Right Cessation
  • 1985-02-25 DE DE8585102053T patent/DE3560728D1/de not_active Expired
  • 1985-02-25 EP EP85102053A patent/EP0158077B1/fr not_active Expired

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