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
  • C14C1/00—Chemical treatment prior to tanning
  • C14C1/08—Deliming; Bating; Pickling; Degreasing
• • 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

• Chrome tanning is an essential step in leather production.
• chromium salts are offered in a concentration which corresponds to an equivalent of 2 to 2.5% Cr 2 0 3 in relation to nakedness in order to achieve a cookable leather.
• 70% are actually permanently fixed in the skin, so that 20 to 30% of the chromium tannin offered ends up in the wastewater.
• the level of chromium tanning can be improved.
• the increased astringency of the chrome tanning agents leads to scarring, i.e. lower quality leathers. In most cases, a loss of space also has to be accepted.
• the temperature of the tanning liquors from the usual 38 to 40'C to approximately 45 ° C, an improved exhaustion of the chrome tanning agents can be achieved.
• the increase in temperature also results in an increase in the astringency of the chrome tanning agents, so that here too there is a risk of scar tension and loss of yield, that is to say the deterioration in the quality of the leather.
• tanning must usually be carried out in two stages in order to reduce these deficiencies by using mild organic tanning which is carried out with mostly organically masked chromium (III) sulfate tanning agent and which is then carried out with the addition of complex-active aromatic di- and tricarboxylic acids follow alone or in the presence of further chrome tanning agent and / or a base agent.
• mild organic tanning which is carried out with mostly organically masked chromium (III) sulfate tanning agent and which is then carried out with the addition of complex-active aromatic di- and tricarboxylic acids follow alone or in the presence of further chrome tanning agent and / or a base agent.
• Preferred aldehyde and keto acids are glyoxalic acid, but also pyruvic acid.
• the pretreatment with these acids is carried out from an aqueous liquor with the above-mentioned concentrations. This pretreatment can be carried out separately, it is expedient to combine the pretreatment with these acids with the pimples.
• the combination with pimples also has the advantage that the addition of the acids mentioned to the pimples eliminates the masking acids that are usually used there, such as formic acid or acetic acid.
• the pimple otherwise contains the usual acids and salts in the usual concentrations.
• the subsequent chrome tanning is carried out using the customary commercially available chromium III tannins using the processes known per se, and the modern self-based chromium III tannins can also be used without problems.
• the advantage of the method according to the invention resides in the fact that when the use of chromium tanning agent is significantly reduced compared to the prior art, the leather quality is not only not adversely affected, but the physical properties such as tensile strength, elongation at break and tear resistance are visibly improved.
• the significantly lower chrome tanning agent supply increased bath consumption and improved fixation of the chrome tanning agent in the leather, the residual chromium content of the exhausted tanning liquors can be reduced to below 0.1%.
• the advantages of the method according to the invention can be seen in the chrome tanning of all common skin types, e.g. Use beef, pork, goat or sheep with success.
• cowhide After a one-hour soak with 500% water at 25 ° C, cowhide is subjected to the main wash with 500% water at 25 ° C, 0.5% of the sodium salt of a benzene disulfonic acid and 0.5% of a polyphosphate for 4 hours in a slowly rotating tanning drum.
• the cowhide is fleshed.
• the liming takes place in the tanning barrel with 300% water at 22 ° C, 4% lime, 3% sulfur sodium, 0.1% alkylaryl polyglycol ether and 0.3% of the ammonium salt of a mixture of amido and imidosulfuric acid.
• the tanning barrel becomes Run for 30 minutes at low speed and then agitate for an additional 23.5 hours every hour for 4 minutes.
• the liquor is drained and rinsed with water at 22 ° C.
• the uncleaved cowhide is weighed and then rinsed again with water at 30 ° C. for 10 minutes.
• the nakedness is taken up in 250% water at 30 ° C and 0.3% of a polyphosphate. After 15 minutes of agitation, the liquor is drained and the nakedness is agitated with 250% water and 1% of the ammonium salt of a mixture of amido and imidosulfuric acid for 20 minutes. Then 2% ammonium sulfate and 1% sodium bisulfite are added and agitated for 60 minutes. Then 0.2% of a bacterial enzyme is added and agitated for a further 30 minutes. After draining the liquor, it is rinsed with water at 18 ° C. for 20 minutes.
• the final pH is 4.0.
• the final temperature is 42 ° C and the chrome content of the tanning liquor is 0.06%.
• the wet blue obtained is cooked.
• the aniline leather which is finished as usual, has a particularly fine grain, a very soft, pleasant feel and high color uniformity.
• cowhide was treated up to the pimple in accordance with Example 1.
• Example 2 After 20 minutes of rinsing and pickling of beef skin, washed and pickled in accordance with Example 1, is taken up in a liquor of 50% water at 18 ° C. and 5% sodium chloride and agitated for 10 minutes in the tanning drum.
• Example 2 After 20 minutes of rinsing and pickling of beef skin, washed and pickled in accordance with Example 1, is taken up in a liquor of 50% water at 18 ° C. and 5% sodium chloride and agitated for 10 minutes in the tanning drum.
• Example 2 After 20 minutes of rinsing and pickling of beef skin, washed and pickled in accordance with Example 1, is taken up in a liquor of 50% water at 18 ° C. and 5% sodium chloride and agitated for 10 minutes in the tanning drum.
• Example 1 ashed and pickled beef skin is rinsed with water at 18 ° C. in one after 20 minutes Brisk of 50% water at 18 ° C and 5% sodium chloride added and agitated for 10 minutes in a tanning barrel.
• the final pH is 4.2.
• the final temperature is 43 ° C and the chromium residual content of the liquor is 0.1%.

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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)

Applications Claiming Priority (2)

Publications (2)

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Cited By (3)

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• 1985
  • 1985-05-10 DE DE19853516842 patent/DE3516842A1/de not_active Withdrawn
• 1986
  • 1986-05-02 EP EP86106024A patent/EP0201054B1/fr not_active Expired
  • 1986-05-02 DE DE8686106024T patent/DE3660552D1/de not_active Expired
  • 1986-05-08 JP JP61103982A patent/JPS61261400A/ja active Granted
  • 1986-05-08 ES ES554783A patent/ES8800727A1/es not_active Expired
  • 1986-05-08 US US06/861,100 patent/US4715861A/en not_active Expired - Lifetime
  • 1986-05-08 YU YU747/86A patent/YU43898B/xx unknown
  • 1986-05-08 KR KR1019860003582A patent/KR940006073B1/ko not_active IP Right Cessation
  • 1986-05-09 BR BR8602098A patent/BR8602098A/pt not_active IP Right Cessation

Non-Patent Citations (1)

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