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
  • C14C3/04—Mineral tanning
  • C14C3/06—Mineral tanning using chromium compounds

Definitions

• the aliphatic dicarboxylic acids are added in the form of their disodium salts to the chrome tanning liquor following the chrome tanning agent.
• the chromium exhaustion is significantly improved compared to a conventional tanning process, but the leather quality can be impaired (cf. K. Faber, loc. Cit. P. 83).
• thick or uncleaved pelt material there is a deterioration in the chromium distribution and the dyeability. This has a negative effect that the penetration of the chrome tanning agent through the skin cross-section is hindered due to the presence of the dicarboxylic acids in the process described (Leder- und Häute nom 30 (1978) 140).
• tanning mixtures consisting of chromium (III) salts, acid-binding agents and aliphatic dicarboxylic acids with 4-6 C atoms or their salts are used in chrome tanning used in advance together with conventional chrome tanning agents.
• chromium (III) salts consisting of chromium (III) salts, acid-binding agents and aliphatic dicarboxylic acids with 4-6 C atoms or their salts
• chrome tanning used in advance together with conventional chrome tanning agents.
• chrome tanning processes in which aliphatic dicarboxylic acids are also used, the total amount of the chrome tanning agent and the dicarboxylic acids in unreacted form must always be added in at least 2 parts of the liquor.
• the theoretical basicity of the reaction product is 0-50%.
• the reaction product can also contain monocarboxylic acids as masking agents.
• the amount used in powdered form is 0.9-1.5%, calculated as chromium (III) oxide (based on the pelt weight) or in aqueous solution at least 5% chromium (III) oxide.
• reaction product used according to the invention hereinafter referred to as chromium-dicarboxylate complex
• chromium-dicarboxylate complex is dried and optionally mixed with the customary acid-binding agents.
• the process according to the invention is carried out in a liquor volume of less than 100%, preferably 10-50% (based on the pelt weight), at a final pH of more than 4.0, preferably 4.2-4.6, and one final -Temperature of over 40 ° C, preferably 42-50 ° C, performed.
• chromium-dicarboxylate complex is not used together with acid-binding agents in chrome tanning, it is blunted in the usual way with alkalis to the desired pH.
• the chromium oxide content of the residual tannins obtained by the process according to the invention is less than 1 g / l.
• the chromium-dicarboxylate complex is prepared by reacting basic chromium (III) sulfates with the corresponding aliphatic dicarboxylic acids with 4-6 C atoms or their mixtures in aqueous solution at temperatures of 50-100 ° C. over a period of 30-80 minutes.
• the desired theoretical basicity of 0-50% is then set with an alkali solution, preferably with a soda solution. (For the calculation of the theoretical basicity, see DE-OS 3 519 287).
• the chromium-dicarboxylate complex thus obtained can be used in the present solution for chrome tanning.
• the solution is evaporated, preferably spray dried.
• the powder tanning agent obtained in this way can be used as such or mixed with acid-binding agents in chrome tanning.
• the basic reaction products of hexavalent chromium compounds with reducing agents which are customary in chrome tanning are suitable as basic chromium (III) sulfates (see, for example, K. Faber, loc. Cit. P. 83). They can additionally contain monocarboxylic acids (eg formic or acetic acid) or their salts as masking agents.
• the chromium oxide content of the solutions according to the invention should be at least 5%, preferably 10 to 15%.
• Aliphatic dicarboxylic acids with 4 to 6 carbon atoms are e.g. Succinic, glutaric, adipic, maleic, fumaric, aspartic and glutamic acid or mixtures thereof. Glutaric acid and adipic acid or mixtures of these acids, if appropriate together with other dicarboxylic acids, are preferably used.
• Suitable acid-binding agents are, for example Dolomite, alkali carbonates and bicarbonates and magnesium oxides.
• Mixtures which contain at least 40% of the total amount of acid-binding agents used in the form of dolomite and / or magnesium oxides with low reactivity are particularly suitable.
• Magnesium oxides with low reactivity are, for example, commercial products such as ®TANBASE (manufacturer: Steetley Quarry Products Ltd.) or ®NEUTRIGAN MO (manufacturer: BASF).
• chrome dicarboxylate complexes according to the invention are also suitable for use in retanning chrome leather.
• 0.3 to 1.5% chromium oxide (based on fold weight) is offered.
• the value of the process according to the invention lies above all in the fact that the use of the chrome dicarboxylate complexes according to the invention enables high emaciations in the chrome tanning with a particularly simple procedure and a particularly low workload without impairing the quality of the leather.
• With only a single addition of chrome tanning agent and dicarboxylic acid residual liquors with a chromium oxide content of less than 1 g / l are obtained. It was not foreseeable that the use of the chromium-dicarboxylate complexes according to the invention would improve the through-tanning to a high degree and that despite the low amount of dicarboxylic acid relative to the chromium supply, such high levels of emaciation could be achieved.
• a chromium-dicarboxylate complex tanning agent with a chromium oxide content of 22.8%, 0.6 mol of adipic acid per mol of chromium oxide and a theoretical basicity of approx. 40% is obtained.
• the remaining liquor contains 0.6 g chromium oxide / l.
• the chrome leathers show excellent tanning when assessed after splitting. After the usual completion, upper leather with a soft, full grip, a fine grain and a very level coloring are obtained.
• the tannin mixture used consists of:
• the chromium oxide content is 19.7%.
• Example 5 100 parts of beef peat pretreated as in Example 5 are mixed with 7 parts of the tannin mixture described below and drummed for 20 hours.
• the final pH is 4.6, the final temperature is 48 ° C; in the remaining liquor there are 0.6 g Cr2O3 / l.
• the tannin mixture used which has a Cr2O3 content of 18.6%, is composed as follows:
• Example 5 100 parts of beef peat pretreated as in Example 5 are mixed with 7.9 parts of a chromium-dicarboxylate complex solution prepared according to the instructions in Example 2. After 1 hour, 1.8% soda (1:15 dissolved), blunted within 1 hour and further tumbling for 15 hours. Towards the end of the tanning, the temperature and pH are 46 ° C and 4.3, respectively. The remaining liquor contains 0.5 g Cr2O3 / l.
• the final temperature of the tanning is 42 ° C, the final pH is 4.3.
• the remaining liquor contains 0.6 g Cr2O3 / l.
• the temperature reached at the end of the tanning is 42 ° C, the final pH is 4.3 and the chromium oxide content of the remaining liquor is 0.8 g / l.
• the leather of the corresponding pieces A has a significantly poorer tanning after splitting.
• upper leather is in the usual way washed 3000 kg beef pelts (split approx. 3.5 mm) in the tanning drum (diameter 3 m, width 3 m, speed of rotation 5 and 10 rev / min) first with 150% (based on paw weight) of water washed at 38 ° C for 10 minutes.
• the liquor is drained and then decalcified with 30% water at 35 ° C with 2% ammonium sulfate, 0.2% sodium bisulfate and 0.2% formic acid for 30 minutes and with 0.5% of a commercial pickling agent (1500 tryptic units) pickled for 30 minutes (pH of the liquor 8.3).
• the temperature is 40 ° C
• the pH is 4.0: the chromium (III) oxide concentration of the remaining liquor was determined to be 0.4 g / l.
• the tanning mixture with a Cr2O3 content of 21.0% is composed as follows:
• the final pH is 4.3 at a temperature of 45 ° C.
• the remaining liquor contains 0.5 g / l Cr2O3.
• the remaining liquor contains 0.2 g / l chromium oxide.
• Example 11 100 parts as ashed, decalcified, pickled and pickled beef (split approx. 2 mm) as in Example 11 are mixed with 5.5 parts of the tanning mixture described below in the pickling liquor and further tumbled for 18 hours.
• the final pH is 4.5, the final temperature is 45 ° C.
• the chromium oxide content of the remaining liquor is 0.3 g / l.
• the liquor contains 0.9 g Cr2O3 / l.

Landscapes

• 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)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6333571

Family Applications (1)

Country Status (13)

Families Citing this family (9)

Family Cites Families (6)

• 1987
  • 1987-08-12 DE DE19873726796 patent/DE3726796A1/de not_active Withdrawn
• 1988
  • 1988-08-01 DE DE8888112496T patent/DE3861936D1/de not_active Expired - Lifetime
  • 1988-08-01 EP EP88112496A patent/EP0304677B1/de not_active Expired - Lifetime
  • 1988-08-01 ES ES88112496T patent/ES2021122B3/es not_active Expired - Lifetime
  • 1988-08-04 MX MX012555A patent/MX169356B/es unknown
  • 1988-08-08 AU AU20587/88A patent/AU607525B2/en not_active Ceased
  • 1988-08-09 NZ NZ225747A patent/NZ225747A/xx unknown
  • 1988-08-09 TR TR88/0593A patent/TR23818A/xx unknown
  • 1988-08-10 JP JP63198110A patent/JPH0814000B2/ja not_active Expired - Lifetime
  • 1988-08-11 ZA ZA885914A patent/ZA885914B/xx unknown
  • 1988-08-11 US US07/231,233 patent/US4919680A/en not_active Expired - Fee Related
  • 1988-08-11 DK DK450488A patent/DK169080B1/da active
  • 1988-08-11 BR BR8804055A patent/BR8804055A/pt not_active IP Right Cessation
  • 1988-08-12 KR KR1019880010287A patent/KR960010048B1/ko not_active IP Right Cessation

Also Published As

Similar Documents

Legal Events