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

• a method for retanning leather is known from US Pat. No. 4,150,944, in which a reaction product is used as the tanning agent, which is obtained by reacting one of e.g. Diphenyl ether,. Phenol and oleum of sulfonation product previously formed with e.g. Dimethylol urea or formaldehyde is available.
• the present invention thus relates to a process for retanning chrome-tanned, optionally dyed leather, in which the leather is treated with an aqueous solution which contains an oligomer as the tanning agent, which contains structural elements of the formulas and if necessary or of the formulas (1), (2), (4) and optionally (3), in which X 1 is -CN, -COOR 1 , -OOCR 2 or -CONHR 3 , Y l -COOH or -COOM 2 , Y 2 -CONH 2 , -CH 2 OH, -OCH 3 or -OC 2 H 5 , Z 1 , Z 2 and Z 3 each hydrogen, methyl or ethyl, M and M 2 each an amine, ammonium or alkali metal cation and R 1 , R 2 and R 3 each denote alkyl, hydroxyalkyl or alkoxyalkyl with a total of at most 8 carbon atoms, and the treated leather greases and dries, before
• the aqueous solution for carrying out the retanning process which contains the oligomer as the tanning agent, the leather retanned by the process and the use of the oligomer as the tanning agent form further objects of the invention.
• the oligomers having structural elements of formulas (1), (2) and (4) are known per se and e.g. in U.S. Patent 3,646,099 as conductive and surface active compounds.
• the oligomers which, in addition to the structural elements (1) and (2) additionally contain the structural element of the formula (3), are known from US Pat. No. 2,893,977 as a component of resin compositions with good adhesive properties.
• oligomers are prepared in the presence of sulfites or hydrogen sulfites, they have structural elements of the formula (4) in one case and not in the other.
• oligomers which are precipitated from their aqueous solutions by addition of strong acids, for example hydrochloric acid, after the known preparation has been completed in the presence of sulfites or hydrogen sulfites contain no or only traces of structural elements of the formula (4).
• sulfite or hydrogen sulfite is present exclusively or at least mainly as a mixing component and not as a structural element of the oligomer in the form of the formula (4) in aqueous solution after the preparation of the oligomers has ended. Since oligomers reprecipitated with hydrochloric acid give the same results as non-reprecipitated oligomers when used as a tanning agent, the presence or absence of structural elements of the formula (4) does not constitute a critical feature of the oligomers used according to the invention. For the retanning process according to the invention, however, the oligomers used do not have to be reprecipitated before they are used.
• the essential feature of the oligomers which can be used according to the invention is the relatively low, average molecular weight, which is preferably at most 14,000, especially 3,000 to 12,000 3,000 to 10,000, in particular 4,000 to 9,000.
• These relatively low molecular weights of the oligomers used according to the invention compared to high molecular weight polymers which e.g. used in the plastics industry for the production of synthetic fibers are caused by the use of sulfites or hydroxysulfites in the production of oligomers.
• preferred oligomers which are used as tanning agents in the process according to the invention each contain 2 to 75, preferably 5 to 40, in particular 10 to 25, structural elements of the formulas (1) and (2) and. 0 to 25, preferably 0 to 10, in particular 0 to 5 structural units of the formula (3).
• oligomers come into consideration which, in addition to the structural elements of the formulas (2) and optionally (3), structural elements of the formula have, wherein X 2 -CN, -COOR 4 , -OOCR 5 or -CONHR 6 , R 4 alkyl, hydroxyalkyl or methoxyalkyl with a total of at most 4 carbon atoms, R 5 methyl or ethyl and R 6 alkyl having 1 to 8 carbon atoms or hydroxyalkyl 1 or 2 carbon atoms, and Z has the meanings given, and in particular structural elements of the formula where X 3 is -CN, -COOCH 3 , -COOC 2 H 5 , -COOC 2 H 4 OH, -COOC 3 H 6 OH, -COOC 2 H 4 OCH 3 , -O O CCH 3 , -OOCC 2 H 5 , -CONHCH 3 , -CONHC 2 H 5 , -CON
• Structural elements of the formulas have structural elements which are particularly suitable as tanning agents and if necessary where X 4 is -CN, -COOCH 3 , -COOC 2 H 5 , -COOC 2 H 4 0H, -COOC 3 H 6 OH, -OOCCH 3 , -OOCC 2 H 5 , -CONHCH 3 , -CONHC 2 H 5 , -CONHC 3 H 7 and -CONHC 8 H 17 , Y 3 -COOH or -COOM 4 , Y 4 -CONH 2 , -CH 2 OH or -OCH 3 , M 3 and M 4 each a sodium, potassium or ammonium cation and Z 4 , Z 5 and Z 6 each represent hydrogen or methyl.
• Oligomers which are of primary interest as tanning agents, have structural elements of the formulas and if necessary on.
• the known oligomers are prepared by methods known per se, which are also described, for example, in US Pat. Nos. 3,646,099 and 3,893,977, by using the compounds of the formulas and if necessary wherein X 1 , Y 1 , Y 2 , Z 1 , Z 2 and Z 3 each have the meanings given, always in the presence of the compounds of the formulas in which M 1 has the meanings given, in an aqueous medium and, if appropriate, in the presence of a polymerization catalyst at a maximum of 70 ° C., and at this temperature the aqueous reaction mixture with a base of the formula wherein M 2 has the meanings given, to a pH of 5 to 7.
• a polymerization catalyst such as azoisobutyronitrile or preferably peroxides, such as benzoyl peroxide or in particular ammonium peroxodisulfate (ie the compound of the formula (NH 4 ) 2 S 2 O 8 ) added to the aqueous solution of the starting compounds in portions, for example in 8 to 12 portions, or within 5 to 8 Hours metered continuously, an exothermic polymerization reaction sets in.
• the reaction mixture is advantageously cooled in such a way that the temperature does not exceed 70 ° C., in particular 40 ° C.
• the polymerization is generally complete 4 to 6 hours after the catalyst has been added.
• the reaction mixture is adjusted to an appropriate pH of about 5 to 7, in particular 6.1 to 6.3, by adding the compound of the formula (10) with cooling so that the temperature indicated above is not exceeded. whereby an aqueous, gel-like solution of the copolymer is obtained.
• the reaction mixture can, if necessary, for the complete removal of any unpolymerized starting compounds, in particular monomers of formula (5), for 6 to 10 hours under reduced pressure (-10 to -1 bar) at 60 can be kept up to 80 ° C.
• sodium, potassium or ammonium sulphite or hydrogen sulfite are used as examples of specific representatives of the starting compounds of the formula (8 ) or (9), acrylonitrile, methacrylonitrile, ethyl acrylonitrile, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, methoxyethyl acrylate, vinyl acrylate, methyl propyl acrylamide, vinyl propyl acrylamide, methyl propyl acrylate, vinyl propyl acrylate, vinyl propyl acrylate, methyl propyl acrylate, vinyl propyl acrylate, vinyl propyl acrylate, vinyl propyl acrylate, methyl propyl acrylate, vinyl propyl acrylate, vinyl propyl acrylate, vinyl propy
• retanning chrome-tanned leather it is expedient to proceed according to methods known per se by treating the leather with an aqueous solution which contains at least one oligomer of the type specified above, rinsing the tanned material in this way if necessary, and then generally greasing it and dries. If desired, coloring can be carried out before the greasing, provided that the leather to be retanned is not already colored.
• 100 to 200, preferably 150 to 200 parts by weight of water and 2 to 50, in particular 5 to 10 parts by weight, calculated on dry substance, of at least one of the oligomers of the type mentioned are used per 100 parts by weight of leather.
• Preferred aqueous solutions for carrying out the retanning process preferably contain 1 to 10, in particular 2 to 5, percent by weight of the oligomer as the tanning agent.
• the leather is treated with the aqueous solution containing the oligomer for 1 to 4 hours at 10 ° C to 50 ° C, preferably 10 ° C to 30 ° C.
• the undyed leather is dyed with commercially available leather dyes, for example acid or metal complex dyes
• the dye is expediently used immediately after retanning by adding the dye of the stated type to the tanning liquor, so that in this case rinsing is generally not necessary.
• the leather is not dyed, it is advantageous to subject the leather to a brief, for example 15 to 30 minute rinse with water at 10 ° C. to 50 ° C., preferably 10 ° C. to 30 ° C., after retanning.
• the retanned, optionally dyed leather is then greased with a customary, preferably lightfast, fatliquor based on, for example, sulfonated sperm oil or claw oil.
• This greasing is carried out for example at 30 ° C to 80 ° C for about 30 to 90 minutes.
• a leather is obtained which has excellent lightfastness, a fine, compact, smooth grain and in particular a soft feel. With undyed leather a very light leather can also be obtained.
• the strong bleaching effect achieved during retanning is particularly advantageous on uncoloured chrome leather.
• the oligomers used as tanning agents according to the invention have excellent compatibility with other commercial tanning agents, for example vegetable tanning agents or synthetic retanning agents, so that the latter can be used together with the oligomers.
• the so-called "wet blue” leather is particularly suitable as chrome-tanned leather, which can be retanned according to the invention, all types of leather, e.g. Calf, cow, goat or sheep leather are considered and the chrome-tanned leather before retanning according to the invention, as usual, as usual with e.g. Formates or bicarbonates is neutralized.
• reaction mixture is used for the removal of unreacted acrylonitrile fractions under reduced pressure and inert for 2 hours Nitrogen atmosphere maintained.
• the emulsion is then adjusted to a pH of 6 using 287.3 parts of a 30% strength aqueous sodium hydroxide solution (2.15 mol), the reaction mixture being cooled so that its temperature does not exceed 40.degree elevated.
• 1000 parts of a light yellow, gel-like, clear, aqueous solution which contains 34% of an oligomer containing about 15 structural elements of the formula (1.4), about 15 structural elements of the formula (2.2) and traces of the structural element of the formula -S0 3 Na.
• Instructions B The procedure described in Instructions A is followed, but a solution of 185.9 parts of acrylic acid (2.58 mol), 64.7 parts of acrylonitrile (1.22 mol) and 19.8 parts of the 40% sodium bisulfite Solution (0.076 mol) in 69.8 parts of water, which with a total of 19.8 parts of the ammonium peroxodisulfate solution in 10 portions, and after dilution with 96 parts of water, with 344 parts of the sodium hydroxide solution (2.58 mol) is moved.
• Instructions C The procedure described in Instructions A is followed, but a solution of 185 parts of acrylic acid (2.56 mol), 34 parts of acrylonitrile (0.64 mol) and 55.6 parts of the sodium bisulfite solution (0.214 mol) is used in 257 Parts of water, which are mixed with a total of 10.7 parts of the ammonium peroxodisulfate solution in 10 portions and, after dilution with 116.4 parts of water, with 341.3 parts of the sodium hydroxide solution (2.56 mol).
• Process D The procedure is as described in instruction A, but a solution of 138.3 parts of acrylic acid (1.92 mol), 127.3 parts of acrylonitrile (2.4 mol), 34.1 parts of acrylamide (0.48 mol ) and 41.6 parts of the sodium bisulfite solution (0.16 mol) in 298.4 parts of water, which together with a total of 11.4 parts of the ammonium peroxodisulfate solution in 10 portions and, after dilution with 92.9 parts of water, 256 parts of the sodium hydroxide solution (1.92 mol) are added.
• Instructions E The procedure described in Instructions A is followed, but an emulsion of 211 parts of acrylic acid (2.92 mol), 141.5 parts of vinyl acetate (1.64 mol) and 43 parts of the 40% sodium bisulfite solution (0.165 mol ) in 80 ml of water, which, at 50 ° C., contains a total of 1.5 parts of ammonium peroxodisulfate in 25 ml of water in 10 portions and, after dilution with 155 parts of water, 320 parts of the sodium hydroxide solution (2.4 mol) becomes.
• reaction mixture 146 parts of a 30% strength aqueous sodium hydroxide solution are then added to the reaction mixture over the course of about 1.5 hours in such a way that the temperature does not rise above 50.degree.
• the reaction mixture is heated to reflux temperature (98-100 ° C.) and kept under a reduced pressure of -0.8 to -1.0 bar for about 8 hours at reflux temperature until a sample of the reaction mixture has less than 100 ppm unconverted acrylonitrile .
• the reaction mixture is then cooled to 20 ° C. and adjusted to a pH of 6.1 to 6.3 by adding a total of about 22 parts of a 30% strength aqueous sodium hydroxide solution in portions.
• About 600 parts of a clear, slightly yellowish solution are obtained which contains 33 to 34% of an oligomer which has 25 to 30 structural elements of the formulas (1.4) and (2.2).
• Instructions G The procedure described in Instructions A is followed, but a solution of 128.4 parts of acrylic acid (1.78 mol), 144.2 parts of methacrylic acid hydroxypropyl ester (1 mol) and 47.4 parts of a 25% strength aqueous potassium hydrogen sulfite solution is used. Solution (0.1 mol) in 100 parts of water with a total of 10 parts of the ammonium peroxodisulfate solution in 10 portions at 60 ° C and, after dilution with 351.5 parts of water, with 218.5 parts of the sodium hydroxide solution (1.63 mol) is added.
• Instructions H The procedure described in Instructions A is followed, but a solution of 73.6 parts of 2-ethoxyacrylic acid (0.51 mol), 93.8 parts of acrylic acid (1.30 mol) and 33.6 parts of a 25 %, aqueous potassium hydrogen sulfite solution (0.07 mol) in 60 parts of water, which with a total of 5 parts of the ammonium peroxodisulfate solution in 5 portions at 60 ° C and, after dilution with 565.8 parts of water, with 168, 2 parts of the sodium hydroxide solution (1.26 mol) is added.
• Instructions I The procedure described in Instructions A is followed, but a solution of 130.7 parts of acrylic acid (1.81 mol), 120.3 parts of acrylonitrile (2.26 mol), 26.3 parts of allyl alcohol (0.40 mol ) and 72.6 parts of a 25% aqueous potassium hydrogen sulfite solution (0.15 mol) in 283.5 parts of water, which together with 37.8 parts of an ammonium peroxodisulfate solution in 5 portions and, after dilution with 87 parts Water, with 241.8 parts of the sodium hydroxide solution (1.81 mol) is added.
• Instructions J The procedure described in Instructions A is followed, but a solution of 133 parts of acrylic acid (1.84 mol), 149.4 parts of methyl acrylate hydroxypropyl ester (1.03 mol) and 49 parts of a 25% strength aqueous potassium hydrogen sulfite solution (0 , 10 mol) in 98.4 parts of water, which with a total of 12.2 parts of the ammonium peroxodisulfate solution in 10 portions at 40 ° C. and, after dilution with 461.7 parts of water, with 96.3 parts of a 30% aqueous ammonia solution (1.7 mol) is added.
• Example 1 100 parts of a chrome-tanned calfskin neutralized in a conventional manner are aftertreated with a solution of 200 parts of water and 5 parts, calculated on dry substance, of the oligomer according to specification A for 1 1/2 hours at 30 ° C. After a short rinse, the aftertreated leather is greased as usual with 4 to 6 parts of a lightfast fatliquor based on sulfonated sperm oil and then dried.
• a leather of light color, excellent lightfastness, with a soft full grip and with a fine grain is obtained. This also applies to the replacement of 5 parts of the oligomer according to. Regulation A by 5 parts of the oligomer according to Regulation F.
• Example 2 100 parts of chrome-tanned sheep leather are mixed with 200 parts of water at 40 ° C. Then 10 parts, calculated on dry substance, of an oligomer according to regulation B are added to the liquor and left to act on the leather for 2 hours at 40 ° C. After rinsing, the treated leather is greased with about 5 parts of a conventional fatliquor and then dried. You get a full, supple leather with a closed, firmly adhering scars. This also applies to the replacement of -10 parts of the oligomer according to regulation B by 10 parts of the oligomer according to regulation C.
• Example 3 100 g of chrome-cooked, folded cowhide leather is neutralized in a barrel in 200 parts of liquor in a known manner to such an extent that the pH of the leather remains below 4 on average.
• the bath is then mixed with 6 parts, calculated on dry substance, of the terpolymer according to regulation D and the neutralized leather is treated at 45 ° C for 2 hours.
• a fresh liquor 300 parts
• 1 part of the dye of the formula the leather is dyed at 60 ° C for 30 minutes.
• the leather is now stretched out and dried.

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• 1982
  • 1982-03-01 EP EP82810091A patent/EP0061420B2/fr not_active Expired - Lifetime
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  • 1982-03-01 US US06/353,114 patent/US4439201A/en not_active Expired - Lifetime
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