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
  • C14C1/00—Chemical treatment prior to tanning
• • 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
• • 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
  • C14C3/16—Chemical tanning by organic agents using aliphatic aldehydes

Definitions

• the present invention relates to an aqueous composition for pre-tanning skin bumps or retanning leather, a method for pre-tanning skin bumps or post-tanning leather and the leather treated by the present method.
• aqueous compositions containing a mixture of a dialdehyde and anionic aromatic tanning agents are outstandingly suitable for pretanning skin bumps or retanning leather, it being possible to dispense entirely with the use of mineral salts.
• the degree of whiteness is significantly improved compared to treatment with glutardialdehyde alone and the shrinkage temperature is sufficient.
• the leathers treated with such a mixture have a firmer structure, which has an advantageous effect during further processing, for example when folding to the desired thickness or when splitting.
• aqueous composition according to the invention very good results can be achieved with regard to pretanning, and the leather has a high shrinking temperature.
• a subsequent non-mineral, in particular chromium salt-free, tanning is possible for the production of wet-white leather material, an aqueous composition according to the invention advantageously being used for this purpose.
• other customary retanning agents can also be used.
• dialdehydes can generally be used as dialdehydes (A). Examples include glyoxal, malondialdehyde, succinic dialdehyde, glutardialdehyde, adipic dialdehyde, pimeline dialdehyde and octanedialdehyde. Preferred representatives are succindialdehyde, glutardialdehyde, adipindialdehyde and glyoxal, of which glutardialdehyde is of primary interest.
• the dialdehydes are usually available as commercially available dialdehydes containing 25 to 50% by weight of water.
• anionic aromatic syntans (B) come e.g. those which are obtainable by condensation of sulfonated aromatic compounds alone or together with further, mostly unsulfonated aromatic compounds with formaldehyde and / or urea.
• Aromatic compounds suitable for this are, for example: naphthalene, diphenyl, terphenyl, phenols, cresols, 4,4'-dihydroxidiphenylsulfone, ⁇ -naphthol, dihydroxybenzenes, resorcinol, 2,2'-bis (hydroxyphenyl) propane and diaryl ethers such as diphenyl ether and Ditolyl ethers which have optionally been sulfonated in a manner known per se.
• condensation products are in the form of the free acids, preferably in the form of the sulfonic acids, or as salts, especially lithium, potassium or in particular sodium salts.
• condensation products are known, for example from Ullmann's Encyclopedia of Industrial Chemistry Vol. 16, (4), 138 to 140 (1979) or can be prepared by the processes described in the references given there.
• Suitable acids (D) are both inorganic and organic acids, for example hydrochloric acid, sulfuric acid, formic acid, acetic acid, citric acid, lactic acid, oxalic acid, benzoic acid, phthalic acid, phenolsulfonic acid, Phenol polysulfonic acid or naphthalenesulfonic acid.
• An organic acid, in particular acetic acid or formic acid, is preferably used. If the solutions of the anionic aromatic tannins already have the desired pH due to the acid groups present in them, component (D) can optionally be dispensed with.
• the proportion of component (A) is preferably between 5 and 95% by weight and the proportion of component (B) is preferably between 5 and 95% by weight.
• the aqueous composition according to the invention is expediently prepared by dissolving component (A) in water at a temperature between 15 and 60 ° C. and then adding component (B) and optionally an acid (D) to the clear solution obtained.
• the aqueous composition thus obtained is liquid and has good storage stability.
• the aqueous composition according to the invention is suitable on its own as an excellent pre-tanning agent for all hides and skins and serves very particularly as a preliminary stage for the production of wet white leather and furs. Subsequent tanning is possible, with an aqueous composition according to the invention advantageously being used for this purpose.
• aqueous composition according to the invention For pre-tanning skin bumps, 1 to 10% by weight, in particular 4 to 8% by weight, of the aqueous composition according to the invention, based on the weight of the skin size, is preferably used.
• aqueous compositions according to the invention are used for retanning leather, then preferably 1 to 10% by weight, in particular 4 to 8% by weight, based on the weight of the leather, is also used.
• Pretanning is carried out, for example, by treating the pickled pelt material with the aqueous composition according to the invention for 1 to 12 hours at a temperature between 15 and 45 ° C and a pH between 1 and 6.5, e.g. in a rolling barrel.
• the material thus obtained can then be dewatered in the usual way and folded or split to the desired thickness and then tanned in the usual way with a mineral tanning agent or, preferably for the production of wet-white material, with vegetable or synthetic tanning agents.
• This retanning can also be carried out with the aqueous composition according to the invention, e.g. by treating the pretanned leather with the aqueous composition according to the invention for 1 to 12 hours at a temperature between 15 and 45 ° C and a pH between 1 and 6.5, e.g. in a rolling barrel.
• the present process can also be used to produce finished tanned leather.
• Example 1 51 parts of naphthalenesulfonic acid are heated with 45 parts of dihydroxydiphenyl sulfone, 30 parts of water and 16 parts of formaldehyde (37% strength) at 105 to 110 ° C. for about 2 hours until the condensate is clearly soluble in water. The mixture is then diluted with 70 parts of water, made weakly acidic with 50 parts of sodium hydroxide solution (30% strength), and 32 parts of glutardialdehyde (50% strength) and 5 parts of formic acid (85% strength) are added.
• a clear, bright solution is obtained which has a pH of 2.0 to 3.0.
• the dry content is 42% by weight.
• the solution is stable for at least 1 month even at 35 ° C and is ideal for pretanning and retanning leather.
• the naphthalene sulfonic acid used is obtained by heating 520 parts of naphthalene and 560 parts of concentrated sulfuric acid at 140 to 160 ° C. for several hours until the reaction product is completely water-soluble.
• the dihydroxydiphenyl sulfone used is obtained by heating 540 parts of phenol and 180 parts of 60% oleum at 170 to 180 ° C. for three hours and distilling off the excess phenol.
• Example 2 500 parts of molten phenol are slowly mixed with 440 parts of 66% oleum at 60 to 70 ° C. and then sulfonated at 100 ° C. for 1 hour. The phenolsulfonic acid formed is then slowly heated in a vacuum from about 11 to 13 mm to 160 to 165 ° C., so that only a little phenol is distilled off, and is kept at this temperature until 1 g of the condensation product is 3.5 to 3.7 cm 3 1 n sodium hydroxide solution neutralized against Congo red. The condensation product formed in this way is mixed with 90 to 100 parts of phenol and after the phenol has been thoroughly mixed, the reaction mass is again slowly placed under vacuum and heated in vacuo at 165 ° C. until 1 g of the condensation product is only 2.7 up to 2.5 cm 3 1 normal sodium hydroxide solution neutralized against Congo red.
• reaction mass is then diluted with 100 parts of water and 33 parts of glutardialdehyde (50%), 3.6 parts of formic acid (85%) and 8 parts of phenolsulfonic acid (65%) are added.
• a clear, bright solution is obtained which has a pH of 4.5 to 5.5.
• the dry content is 42% by weight.
• the solution is stable for at least 1 month even at 35 ° C and is ideal for pretanning and retanning leather.
• Example 3 If the procedure described in Example 2 is followed, but instead of 54 parts of 30% sodium hydroxide solution, an equivalent amount of lithium hydroxide is used, a storage-stable solution is also obtained which is suitable for tanning and retanning leather.
• Example 4 478 parts of 20% oleum are added to 500 parts of molten phenol with stirring, the cooling being used to ensure that the temperature does not exceed 70.degree. The mixture is then sulfonated at 105 ° C. for 1 hour. The phenolsulfonic acid formed is slowly heated to 150 to 155 ° C. under reduced pressure of 11 to 13 torr, and this temperature is maintained until 1 g of the condensation product 3.8 to 4.0 cm 3 of normal sodium hydroxide solution is neutralized against Congo red.
• the reaction product obtained is diluted with 27.6 parts of water and made weakly acidic with 37.2 parts of potassium hydroxide solution (50%). Then 42 parts of glutardialdehyde (50%), 42 parts of acetic acid (75%) are added.
• a clear, bright solution is obtained which has a pH of 2.5 to 3.5.
• the dry content is 53% by weight.
• the solution is stable for at least 1 month even at 35 ° C and is ideal for pretanning and retanning leather.
• Example 5 55 parts of phenolsulfonic acid are mixed with 25 parts of dihydroxydiphenyl sulfone, 35 parts of water and 56 parts of 30% sodium hydroxide solution and then mixed with 61.5 parts of 37% formaldehyde solution and at 100 to 105 ° C. for as long (about 6 hours) condenses until a sample diluted with a little water remains clear when acidified with dilute sulfuric acid up to a pH of 3.5.
• reaction mass is then diluted with 30 parts of water and mixed with 33 parts of glutardialdehyde (50%), 3.6 parts of formic acid (85%) and 5 parts of sulfuric acid (40%).
• a clear, bright solution is obtained which has a pH of 4.0 to 5.0.
• the dry content is 40% by weight.
• the solution is stable for at least 1 month even at 35 ° C and is ideal for pretanning and retanning leather.
• Example 6 100 parts of a pickled calf pod are treated with 5% of the agent prepared according to Example 2 for 3 to 6 hours at 25 ° C. in a rolling barrel, the pH being adjusted to 4.5 with powdered sodium hydrogen carbonate or sodium formate.
• the leather treated in this way (wet white leather) is dewatered and folded to the desired thickness.
• This leather is ideal for retanning with mineral, vegetable or synthetic tanning agents.
• the leather can also be retanned using the same agent prepared in accordance with Example 2, thus obtaining heavy metal-free tanned leather.

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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)
• Phenolic Resins Or Amino Resins (AREA)

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• 1995
  • 1995-12-06 EP EP95810768A patent/EP0717114A3/fr not_active Withdrawn
  • 1995-12-13 AR AR33459995A patent/AR000337A1/es unknown
  • 1995-12-14 ZA ZA9510648A patent/ZA9510648B/xx unknown
  • 1995-12-14 AU AU40461/95A patent/AU689984B2/en not_active Ceased
  • 1995-12-14 BR BR9505896A patent/BR9505896A/pt not_active Application Discontinuation
  • 1995-12-15 KR KR1019950050317A patent/KR960023088A/ko not_active Application Discontinuation
  • 1995-12-15 JP JP7326144A patent/JPH08232000A/ja active Pending
• 1997
  • 1997-02-18 US US08/802,648 patent/US5733340A/en not_active Expired - Fee Related

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