US3533724A - Substantially dry syntan or waste sulfite liquor pretannage of vegetable tanned or syntanned leather - Google Patents

Substantially dry syntan or waste sulfite liquor pretannage of vegetable tanned or syntanned leather Download PDF

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US3533724A
US3533724A US525833A US3533724DA US3533724A US 3533724 A US3533724 A US 3533724A US 525833 A US525833 A US 525833A US 3533724D A US3533724D A US 3533724DA US 3533724 A US3533724 A US 3533724A
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tanning
leather
weight
liquor
pelts
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US525833A
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Wolfhard Luck
Bruno Zinz
Helmut Schmid
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Bayer AG
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Bayer AG
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    • 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

Definitions

  • Rapid tanning processes for the production of medium weight and heavy leather Which is tanned with vegetable tannins or syntans are known from US. Pat. Nos. 3,253; 879 and 3,254,937; in these processes the hides which are pretanned with chromium-containing tanning agents, are finally tanned with vegetable tannins and syntans in powdered form without a liquor in the drum within a short time.
  • these tanning processes without a liquor have the substantial advantage that no residual liquors remain after tanning and that a very high acceleration of the tanning is achieved, due to the very high initial concentration of the tannins.
  • the acidification of the pelts requires a specific amount of acid, which is comparatively high for the organic acids without swelling action, because of their high equivalent weight.
  • these organic acids are furthermore obtainable only at a relatively high price, and their practical use is therefore restricted for economic reasons.
  • naphthalene-sulphonic acids are used as acidification agents, it must also be taken into account that these acids which also have a strong corrosive effect on metals, are highly hygroscopic and available in the form of pastes or blocks which are difficult to handle.
  • auxiliary syntans as distinct from exchange syntans, comprises those syntans of aromatic nature which have themselves no good tanning action, or none at all (for definition of tanning adjuvants and exchange syntans see e.g. A. Kuntzel, Das Leder, 6 (1955), pages 200-207, particularly page 202, paragraph 1).
  • the auxiliary syntans chiefly comprise the group of condensation products from naphthalene-sulphonic acids with formaldehyde as well as phenolic novolaks which are comparatively strongly sulphonated.
  • Such more strongly sulphonated nolalaks contain e.g. on average, about 0.8-1.0 sulphonic acid groups linked to One phenyl radical (regarding the term novolaks see B. K. Hultzsch, Chemie der Phenolharze, (1950), page 107).
  • Auxiliary syntans based on naphthalene-sulphonic acid/ formaldehyde condensation products are especially suitable for the new process.
  • those condensation products from naphthalene-sulphonic acids and formaldehyde have proved to be advantageous, which are adjusted to an acid number of at least 30, preferably 50- 120, and which may also contain 5-20% of their weight of water-soluble inorganic neutral salts.
  • acid number there is to be understood the consumption of mg. KOH for neutralizing l g. dry substance of the tanning agent.
  • sulphite waste liquor is known to mean technical mixtures which contain, as the main component, lignin-sulphonic acid in the form of its salts, especially the sodium salts.
  • aliphatic carboxylic acids are chiefly suitable, such as acetic acid, formic acid, glutaric acid or adipic acid.
  • Liquid as well as solid acids can be admixed to the naphthalene-sulphonic acid condensation products or to the sulphite waste liquor.
  • water-soluble inorganic neutral salts are, inter alia, sodium sulphate, sodium chloride, potassium sulphate, potassium chloride, ammonium sulphate, ammonium chloride, and other known water-soluble inorganic salts of neutral reaction.
  • exchange syntans may be used together with the auxiliary syntans for pre-tanning.
  • the proportion of exchange syntans should normally not exceed about 50% of the total amount of pre-tanning agents.
  • Pre-tanning is carried out without a liquor and continued until the pelts are completely tanned through.
  • About -15% pre-tanning agent, referred to the pelt weight are sufiicient for this purpose; about 23-10% pretanning agent are preferably used.
  • the pre-tanning is completed after 2-4 hours.
  • the final tanning with vegetable tannins and/or syntans is carried out by known methods.
  • tanning without a liquor in the meaning of the present invention comprises those tanning processes in which the tanning agents are used without water or without substantial amounts of water.
  • the pre-tanning agents are normally used in powdered form, but the It is generally known to use syntans in a liquor for the pre-tanning of hides. If 5-15%, referred to the pelt weight, are used, the pelts are tanned only superficially and a complete tanning through is not achieved. If the concentration of syntan is increased while the liquor ratio remains the same, i.e. if the amount of syntan, referred to the pelt weight, is increased, a tanning through can be achieved.
  • the pelt absorbs more than 5-15 syntan, and the tanning process takes considerable more time than the pre-tanning according to the new process. Furthermore, the amount of syntan absorbed and the amount of syntan required to achieve the tanning through are the greater the more astringent the syntan. If fairly large amounts of syntan are absorbed, the character of the leather is already determined to a large extent by the pretanning agent, and this process can no longer be regarded as a pre-tanning in the strict meaning of the term.
  • the final tanning of the pelts which have been pre-tanned according to the new process and rinsed can advantageously be carried out with vegetable tannins and/or syntans without a liquor.
  • the process according to the invention makes it possible to carry out the final tanning without a liquor also on an industrial scale without the risk of case-hardening or of an undesired strong formation of drawn grain.
  • the process according to the invention is particularly suitable for the production of welting leather, vachettes, inside sole leather, sole leather splits or sole leather.
  • EXAMPLE 1 An unsplit cow butt of 8 mm. thickness which has been limed in the lime house in the manner customary for sole leather is divided into pieces of 8 x 30 cm. The pieces are drummed in the drum overnight in 300% water, 2% ammonium sulphate, 1.5% sodium metabisulphite and 0.5% of formic acid (all percentages are referred to the pelt weight).
  • the completely delimed pelt pieces After discharging the liquor (pH value about 6), the completely delimed pelt pieces the cross-section of which is coloured level yellow to yellowgreen by the bromothymol blue indicator, are drummed with water, 7% sodium chloride, 1.5% sulphuric acid (66 Be'.) and 1% calcium formate for about 1 to 2 hours and then left in the liquor overnight (pH value about 3.2 to 3.5).
  • Some of the pelt pieces are then pretanned without a liquor in a drumming machine as described by E. Kornarek and G. Mauthe in Das Leder 12 (1961), pages 285289, particularly page 287, with 10% of the pre-tanning agent described below.
  • the pelt is completely tanned through after a total drumming time of about 5 hours.
  • the vegetable tannin mixture consists of 60 parts by the drum with 400% water and 35% pure tannin of the mixture of vegetable tannins described below. Half of the vegetable tannin is used immediately, the remaining part is added in 3 portions at time intervals of 3 hours.
  • the vegtable tannin mixture consists of 60 parts by weight pure tannin of chestnut (normal), 20 parts by weight pure tannin of mimosa, 10 parts by weight pure tannin of valonia and 10 parts by weight pure tannin of myrobalams.
  • EXAMPLE 2 150 parts by weight of shoulders of alkaline cow pelts (splitting substance 3.5-4 mm.) which are suitable for the production of welting leather and have been limed in the lime house in the usual manner, are first washed with 500% water (all percentages are referred to the pelt weight) and then rinsed with water at 20-25 C. for 5 minutes. After draining the rinsing liquor, the pelts are delimed with 300% water, 2% ammonium sulphate, 1.5% sodium metabisulphite and 0.3% of 37% hydrochloric acid. After a drumming time of 2 to 3 hours, the
  • the liquor is drained.
  • the pelts are then drummed with 60% water at 20 C., 5% sodium chloride, 1.5% calcium formate and 1.2% sulphuric acid (66 B.) for about 2 hours and left in the pickling liquor overnight.
  • the pickling liquor which has a pH value of about 3.6-3.8 is then drained as far as possible.
  • pre-tanning agent there is used a powdered mixture of 50 parts by weight of a condensation product which has been obtained from a technical naphthalenesulphonation mixture mainly containing fi-naphthalenesulphonic acid with 0.65 mol formaldehyde per mol naphthalene-sulphonic acid and is present in the form of the sodium salt, 25 parts by weight purified delimed sulphite waste liquor (sodium salt) and parts by weight of a condensation product prepared by known methods from 1.5 mol ,B-naphthalene-sulphonic acid, 1 mol dihydroxy-diphenyl-sulphone and about 1.25 mol formaldehyde, as well as 10 parts by weight glutaric acid.
  • a condensation product and process for preparing it is found in German Pat. 611,671, corresponding to US. Pat. 1,901,536.
  • the acidified pelts are subsequently further drummed in the same drum with 8% powdered pre-tanning agent.
  • the pre-tanning agent consists of parts by weight of a condensation product obtained from a technical naphthalene-sulphonation mixture mainly containing fl-naphthalene-sulphonic acid with 0.65 mol formaldehyde per mol naphthalene-sulphonic acid, 10 parts by weight sodium sulphate and 10 parts by weight adipic acid.
  • the pelts are evenly tanned through after a drumming time of 2 to 3 hours; they are rinsed to removethe salts.
  • the leather is completely tanned after a total tanning time of about 4-5 hours; it is then fat-liquored and finished in the usual manner.
  • a pale leather of level shade is obtained which exhibits only a negligible drawn grain, or none at all.
  • the acidic pelts are then drummed without a liquor and with the addition of 0.5% acetic acid, with 10% of a powdered mixture of 50 parts by weight of the spraydried sodium salt of a condensation product obtained from 1 mol fl-naphthalene-sulphonic acid with 1 mol formaldehyde, and 50 parts by weight of a spray-dried resin obtained by condensation of 1 mol 4,4'-dihydro-xy-diphenyl-sulphone with 1 mol B-naphthalene-sulphonic acid and 1 mol formaldehyde, followed by neutralisation with a sodium hydroxide solution.
  • the leather is washed with 300% water at about 30 C. for 10 minutes and then rinsed with water at 30 C. for 10 minutes.
  • pre-tanning agent there is used a spray-dried condensation product obtained from a technical naphthalenesulphonation mixture mainly containing naphthalene B- sulphonic acid with 0.65 mol formaldehyde per mol naphthalene-sulphonic acid, which is present in the form of the ammonium salt and has been adjusted to an acid number of about by the addition of glutaric acid.
  • the pretanning agent used is a powdered mixture of 50 parts by weight of a spray-dried delimed sulphite waste liquor in form of its sodium salt, and 50% of an exchange syntan.
  • the exchange syntan was prepared by reaction of 1 mol of phenol sulphonic acid with 1.2 mol of urea and 1.7 mol of formaldehyde, after-treatment of the reaction product thus obtained with 0.75 mol of phenol and 0.56 mol of formaldehyde, neutralisation with soda-lye, spraydrying of the mixture and adding adipic acid. Adipic acid is added in an amount sufiicient to adjust the acid number of the powdered mixture to 100.
  • the final tanning After completion of the pretanning and rinsing the final tanning is subsequently carried out in the same drum after draining the liquor.
  • the leathers obtained are finished in the usual manner. One obtains smooth and flexible sole leather.
  • the pretanning agent contains 35 parts by weight of a spray-dried neutral condensation product of a technical naphthalene sulphonation and formaldehyde, in form of its sodium salt.
  • the technical naphthalene sulphonation consists essentially of B-naphthalene sulphonic acid.
  • the molar ratio between naphthalene sulphonic acid and formaldehyde amounts to 1:07.
  • the pretanning agent further contains 35 parts by weight of a neutral spray-dried condensation product of 1 mol of fi-naphthalene sulphonic acid, 0.5 mol of o-chlorophenol and 0.87 mol of formaldehyde, in form of its sodium salt.
  • the pretanning agent further contains 10 parts by weight of unhydrous oxalic acid and parts by weight of ammonium sulphate or potassium sulphate.
  • the pretanning agent contains 10% (referred to the 'weight of the pelt) of a spray-dried neutral condensation product of [i-naphthalene sulphonic acid and formaldehyde (molar ratio 1:065), in form of its ammonium salt and 10% of a sirupy exchange syntan which contains a condensation product of 1 mol of naphthalene sulphonic acid, 1.9 mol of pyrocatechol and 1.46 mol of formaldehyde, neutralised with ammonia and adjusted to an acid number of (referred to the solid content of the exchange syntan) by the addition of acetic acid.
  • the leather thus obtainable has excellent properties.
  • EXAMPLE 10 Pickled pelts, e.g. goat pelts, which are suitable for the production of lining leather are drummed with about 20% (referred to the weight of the pelt) of water of 20 C. for 20 to 30 minutes. The water shall be completely absorbed by the pelts. 7% of a powdered spray-dried neutral condensation product of fi-naphthalene sulphonic acid and formaldehyde, in the form of its sodium salt are then added. After having drummed for some minutes about 1% of sodium acetate (1:10 dissolved in water) are added. The amount of sodium acetate shall be cal culated in such a manner as to adjust the pH of the small amount of liquor which is present in the drum to 3.2 to 3.5.
  • the amount of sodium acetate shall be cal culated in such a manner as to adjust the pH of the small amount of liquor which is present in the drum to 3.2 to 3.5.
  • a pure tannin which is a mixture of 50 parts by weight of pure tannin of sulphited quebracho extract and 25 parts by weight of pure tannin of a chestnut extract and 25 parts by weight of pure tannin of a weakly sulphited quebracho extract.
  • the leathers thus obtained are fat-liquored and finished in the usual manner. One obtains smooth leather without drawn grain.
  • auxiliary syntan employed as a pretanning agent is a condensation product of one or more naphthalene sulfonic acids and formaldehyde.
  • auxiliary syntan employed as a pretanning agent is a condensation product of one or more naphthalene sulfonic acids and forinalde- 9 10 hyde, which product is acidified with at least one inor- OTHER REFERENCES gapic acid or organifi acid in the amolmt suflicient to Berkman: Journal of the American Leather Chemists ad ust the acid number of the pretanning agent to at Association, An Investigation of Synthetic Tanning Maleast terials, August 1947, pp. 409, 415.
  • pretanning agent is (c) a mixture of sulfite waste liquor with not more than 50% by weight of an exchange syntan based on said sulfite waste liquor.

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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)
US525833A 1965-02-10 1966-02-08 Substantially dry syntan or waste sulfite liquor pretannage of vegetable tanned or syntanned leather Expired - Lifetime US3533724A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115074467A (zh) * 2021-03-16 2022-09-20 施华团队股份公司 皮革鞣制方法、阴离子活性剂组合物、阳离子活性剂用于皮革预鞣制的用途及鞣制皮革

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2040212A (en) * 1936-05-12 Water-soluble condensation
US2129553A (en) * 1938-09-06 Tanning material
US2955904A (en) * 1956-09-11 1960-10-11 Schnoller Desiderio Rapid process for tanning hides
US3253879A (en) * 1961-07-19 1966-05-31 Bayer Ag Chrome-syntan pretannage followed by dry chrome tannage
US3254937A (en) * 1961-08-03 1966-06-07 Bayer Ag Dry chrome pretannage and dry syntan or vegetable tannage

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2040212A (en) * 1936-05-12 Water-soluble condensation
US2129553A (en) * 1938-09-06 Tanning material
US2955904A (en) * 1956-09-11 1960-10-11 Schnoller Desiderio Rapid process for tanning hides
US3253879A (en) * 1961-07-19 1966-05-31 Bayer Ag Chrome-syntan pretannage followed by dry chrome tannage
US3254937A (en) * 1961-08-03 1966-06-07 Bayer Ag Dry chrome pretannage and dry syntan or vegetable tannage

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115074467A (zh) * 2021-03-16 2022-09-20 施华团队股份公司 皮革鞣制方法、阴离子活性剂组合物、阳离子活性剂用于皮革预鞣制的用途及鞣制皮革

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DE1494839C3 (de) 1975-04-10
CH466494A (de) 1968-12-15
DE1494839B2 (de) 1973-03-01
NL6601713A (en)) 1966-08-11
GB1126823A (en) 1968-09-11
BE676243A (en)) 1966-06-16
DE1494839A1 (de) 1972-02-10

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