EP0347373B1 - Aqueous solutions of synthetic tanning agents - Google Patents

Description

The present invention relates to aqueous solutions of synthetic tanning agents, their use for tanning pelts or retanning leather and lithium salts of such tanning agents.

In aqueous tanning solutions, the tanning agents are generally present as ammonium salts. These salts cause unpleasant smells and pollute the resulting wastewater.

It has now been found that tannins in the form of their lithium salts do not have these disadvantages.

• (A) ein Lithiumsalz eines synthetischen, anionischen aromatischen Gerbstoffes ausgewählt aus der Gruppe, bestehend aus
  • (I) Kondensationsprodukten aus sulfoniertem Phenol oder Kresol und Formaldehyd,
  • (II) Kondensationsprodukten aus Naphtalinsulfonsäure und Formaldehyd,
  • (III) Formaldehyd-Kondensationsprodukten von 4,4'-Dihydroxydiphenylsulfonen mit (Hydroxy)arylsulfonsäuren,
  • (IV) Formaldehyd-Kondensationsprodukten von sulfogruppenhaltigen aromatischen Hydroxyverbindungen mit Aralkylhalogeniden,
  • (V) Harnstoff-Formaldehyd-Kondensationsprodukten von Phenolen und Phenolsulfonsäuren,
  • (VI) Umsetzungsprodukten aus Phenol und einem Sulfonierungsmittel, wobei das Molverhältnis (Phenol):(SO₃) (1):(1,1-2,2) beträgt,
  • (VII) Kondensationsprodukten aus sulfonierten Diarylethern und Formaldehyd,
  • (VIII) Kondensationsprodukten aus sulfonierten Di- oder Terphenylen und Formaldehyd,
  • (IX) Kondensationsprodukten aus 4,4'-Dihydroxydiphenylsulfon und sulfoniertem 4,4'-Dihydroxydiphenylsulfon mit Formaldehyd und
  • (X) Formaldehyd-Kondensationsprodukten aus Diarylethersulfonsäure und 4,4'-Dihydroxydiphenylsulfon und gegebenenfalls
• (B) ein wasserlösliches Chrom-, Aluminium-, Eisen- oder Zirkoniumsalz oder dessen Gemische und
• (C) ein Alkalimetallsalz der Ethylendiamintetraessigsäure oder eines Pyrophosphates

enthält.The present invention thus relates to an aqueous solution of synthetic tanning agents, which is characterized in that it

• (A) a lithium salt of a synthetic, anionic aromatic tanning agent selected from the group consisting of
  • (I) condensation products of sulfonated phenol or cresol and formaldehyde,
  • (II) condensation products of naphthalene sulfonic acid and formaldehyde,
  • (III) formaldehyde condensation products of 4,4'-dihydroxydiphenyl sulfones with (hydroxy) aryl sulfonic acids,
  • (IV) formaldehyde condensation products of sulfo-containing aromatic hydroxy compounds with aralkyl halides,
  • (V) urea-formaldehyde condensation products of phenols and phenolsulfonic acids,
  • (VI) reaction products of phenol and a sulfonating agent, the molar ratio (phenol) :( SO₃) (1) :( being 1.1-2.2),
  • (VII) condensation products from sulfonated diaryl ethers and formaldehyde,
  • (VIII) condensation products of sulfonated di- or terphenylene and formaldehyde,
  • (IX) condensation products of 4,4'-dihydroxydiphenyl sulfone and sulfonated 4,4'-dihydroxydiphenyl sulfone with formaldehyde and
  • (X) formaldehyde condensation products of diaryl ether sulfonic acid and 4,4'-dihydroxydiphenyl sulfone and optionally
• (B) a water-soluble chromium, aluminum, iron or zirconium salt or mixtures thereof and
• (C) an alkali metal salt of ethylenediaminetetraacetic acid or a pyrophosphate

contains.

The synthetic aromatic tanning agents of component (A) are known per se, for example from Ullmann's Encyclopedia of Industrial Chemistry Vol. 16, (4) 138-140 (1979).

The lithium salts which can be used according to the invention are new and represent a further subject of the present invention.

The condensation products of types (I) - (III), (V) and (VII) - (X) are known, for example, from Ullmann's Encyclopedia of Industrial Chemistry, Vol. 16, (4), 140 (1979) and can be described in the The processes described there can be produced.

Condensation products of type (IV) and their preparation are known from GB-C-986621.

Condensation products of type (V) and their production are known from GB-C-890160 and 935678.

The reaction product of type (VI) and its preparation are known from EP-A-0245205. These reaction products can be condensed to products of type (V) by methods known per se (cf. e.g. GB-C-683084).

The ready-to-use tanning salts suitable for component (B) are described in the relevant specialist literature. These are usually chromium, aluminum, iron or zirconium salts. Examples of such salts are basic chromium (III) chloride or sulfate, a chrome alum, optionally basic aluminum chloride or sulfate, an alum, iron (III) chloride or sulfate, zirconium oxychloride and zirconium sulfate. Mixtures of the chromium and aluminum salts mentioned are also suitable as components (B) to be used. Preferred are, however, [CrCl₂ (OH₂) ₄] Cl · 2 H₂O, [Cr (OH₂) ₆] Cl₃, Cr (OH) SO₄, Cr₂ (OH) ₄SO₄, KCr (SO₄) ₂ · 12 H₂O, AlCl₃ · 6 H₂O, Al₂ (SO₄) ₃ · 16 H₂O, Al₂ (OH) ₄SO₄, Al (OH) ₂Cl, Al (OH) Cl₂, KAl (SO₄) ₂ · 12 H₂O, Fe₂ (SO₄) ₃ · 9 H₂O, Zr (OH) ₂SO₄ , ZrOCl₂ · 8 H₂O and Zr (SO₄) ₂ · 4 H₂O.

Of primary interest are the basic chromium sulfates Cr (OH) SO₄ and Cr₂ (OH) ₄SO₄, which are available from chromium alum and an alkali in an equivalent ratio of 3: 1 and 3: 2.

If the optional component (C) is also used in the composition according to the invention, preference is given to the tetrasodium salt of ethylenediaminetetraacetic acid or the neutral or acidic sodium pyrophosphate (Na₄P₂O₇ or Na₂H₂P₂O₇). The optional component (C) acts as a complexing agent and is preferably used in the composition in the case of an iron-free tanning agent, provided the iron content of the oleum used in the production of component (A) is relatively high.

Since the tanning salts of the specified type have very different molecular weights as component (B), the weights of component (B) in the weight ratio of component (A) to component (B) are advantageously based on the metal atom of the corresponding tanning salts. In addition, when using chrome tanning salts as component (C), a maximum of 0.375 parts of chromium per part of component (A) can be used. Higher amounts of chromium would no longer be soluble in the composition and would lead to inhomogeneous compositions. Thus preferred compositions contain components (A) and (B) in a weight ratio (A) :( B) of (1) :( 0.03 to 0.5), based on the metal atom of component (B), at most 0.375 parts of chrome are present. Compositions which have the highest possible levels of tanning salts are desirable, since the tanning salts as component (B) are cheaper in comparison to the reaction products of phenol and oleum as component (A), the tanning effect of the composition on both component (A) and is also due to component (B). Thus, compositions which contain components (A) and (B) in a weight ratio (A) :( B) of (1) :( 0.3 to 0.375) are particularly preferred.

If the optional component (C) is also used, the use of 0.04 part by weight of component (C) per part by weight of component (A) is sufficient to achieve the complexing effect of component (C). Thus, as a rule, the compositions contain the components (A) and (C) in a weight ratio (A) :( C) of (1) :( 0 to 0.04).

A solution according to the invention diluted with water to 1%, based on the dry substance of components (A) and optionally (B) and (C), has a pH of at most 5. The 1% aqueous solutions of compositions according to the invention preferably have a pH of 0 to 3.5.

In general, the compositions according to the invention have a water content of 40 to 80, preferably 45 to 62 percent by weight.

In the preparation of the composition according to the invention, the procedure is generally such that an aqueous solution of component (A) and, if appropriate, component (C) are mixed with component (B), which may be present as an aqueous solution. Before mixing with optionally component (C), component (A) should first be diluted with water for safety reasons, about 50 to 70 percent by weight solutions of component (A) being obtained. As a rule, the optional component (C) is slowly added to the aqueous solution of component (A).

Only at the end is component (B) optionally added to the mixture of components (A) and optionally (C). Component (C) can be added as a solid with vigorous stirring. This applies in particular when using, for example, aluminum tanning salts as component (B). When using chrome tanning salts, it has proven to be particularly advantageous to use component (B) as an aqueous solution, this aqueous solution, before mixing with components (A) and optionally (C), generally at 60 to 90 ° C. is heated. After all the components have been mixed, the composition is generally diluted with water to the preferred water content of 40 to 80 percent by weight.

The aqueous solutions of synthetic tanning agents preferably contain
5 to 60% by weight of component (A),
0 to 60% by weight of component (B),
0 to 60% by weight of component (C) and
ad 100 wt.% water

The compositions according to the invention obtained in this way are liquid and are particularly suitable for tanning raw materials or for retanning leather of all kinds.

The conventional methods are used to treat pale or pretanned leather with an aqueous solution which contains the aqueous composition according to the invention, and then the material which has been tanned in the usual way, e.g. by neutralizing, washing out, greasing and drying. If desired, staining can be done. As a rule, 100 to 200, preferably 140 to 180 parts by weight of water and 5 to 40 parts by weight of the aqueous composition according to the invention are used per 100 parts by weight of leather or leather.

In particular, 100 parts by weight, preferably descaled, of tanned material are tanned with 140 to 160 parts by weight of water and 10 to 20 parts of the composition according to the invention, or 100 parts by weight in the usual manner, chrome-tanned leather neutralized with, for example, formates or bicarbonates, with 140 to 160 parts by weight of water and 5 to 15 parts retanned the composition according to the invention. The tanned material is rinsed and, if necessary, subsequently greased with a commercially available fatliquor based on, for example, sulfonated fish oil, sperm oil or claw oil. After drying, a light, brilliant leather is obtained, which has good lightfastness, a firm, compact, smooth grain and a soft handle.

In addition to the good properties of the materials tanned with it, the composition according to the invention has the essential advantage of being particularly stable in storage. Even after several months of storage, no clouding or flocculation can be found in the composition.

In addition, the lithium salts according to the invention can also be used with polyamide fibers to improve the wet fastness of dyeings or as stain protection agents (stain blockers).

In addition, these lithium salts can also be used as dispersants, especially for dyes and chemicals.

The new lithium salts are produced by neutralizing the anionic syntane with lithium hydroxide or lithium hydroxide monohydrate.

The percentages and parts given in the following manufacturing instructions and in the following examples relate to the weight.

Manufacturing instructions for component (A) Regulation A:

als Hauptbestandteil enthält.136.5 parts of phenol (1.45 moles) are melted at 45 ° C. To this melt 193.4 parts of 20% oleum (2.08 mol SO₃) are slowly added so that the temperature of the reaction mixture does not rise above 160 ° C. Now the reaction mixture is kept under reduced pressure at 26 mbar and at 160 ° C. for 6 hours with stirring, the water formed by the reaction together with small amounts of molten phenol being removed from the reaction mixture azeotropically. The reaction mixture is then cooled to 40 ° C. under normal pressure. This gives 253 parts of a molten mixture of polyhydroxy-polyphenylsulfonic sulfonic acids, which is the disulfonic acid of the formula

contains as main ingredient.

Manufacturing example Example 1:

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 14 to 17 mbar 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 1N sodium hydroxide solution neutralized against Congo red. The resulting condensation product is mixed with 90 to 100 parts of phenol, and as soon as the phenol is thoroughly mixed, the reaction mass is again slowly put under vacuum and heated at 165 ° C until 1 g of the condensation product is only 2.7 to 2.5 cm³ of 1N sodium hydroxide solution neutralized against Congo red. Yield 900-940 parts.

82 parts of the condensation product obtained are diluted with 36 parts of water and neutralized with 16.2 parts of lithium hydroxide monohydrate and mixed with 13.1 parts of 37% formaldehyde solution and condensed at 100 to 105 ° C. for about 6 hours until a sample is obtained diluted a little water remains clear when acidified with dilute sulfuric acid. The reaction mass is then diluted with 50 parts of water, the resulting tanning agent is adjusted to pH 3.5 with 13 parts of 40% sulfuric acid and acidified with 14 parts of 85% formic acid.

A clear and stable tannin solution with a total residue of approx. 47% is obtained. This tanning agent is particularly suitable for the production of white leather.

Example 2:

30 parts of water are slowly added to a solution of 70 parts of the reaction product of phenol and oleum prepared according to regulation A and the pH is adjusted to 3.5 with 20 parts of lithium hydroxide monohydrate. The temperature of the reaction mixture should not rise above 70 ° C. The solution obtained is 75% with 10 parts Acidic acidified (total residue approx. 56%). The treatment of a chrome grain leather with this stable tannin solution according to the usual method has full scars and a soft handle.

Example 3:

4.5 parts of lithium hydroxide monohydrate are slowly added to a solution of 166.5 parts of the reaction product of phenol and oleum, 100 parts of water and 4 parts of tetrasodium salt of ethylenediaminetetraacetic acid prepared in accordance with specification A in such a way that the temperature of the reaction mixture does not rise above 70.degree. The reaction mixture is kept under stirring at 70 ° C. for 15 minutes, a clear solution being formed. Now a solution of 198 parts of Cr (OH) SO₄ (corresponding to 62.3 parts of chromium) in 360.5 parts of water, preheated to 70 ° C., is added to the reaction solution. The reaction solution is then kept under stirring at 70 ° C. for 20 minutes, then diluted with 166.5 parts of water and cooled to 20 ° C. After 3 months of storage, the composition remains homogeneous, i.e. shows no cloudiness or flocculation.

Example 4 :

To a solution of 150 parts of a reaction product obtained by heating to 105 to 110 ° C of 51 parts of a naphthalenesulfonic acid mixture, 51 parts of 4,4'-dihydroxydiphenylsulfone, 25 parts of water and 23 parts of 30% formaldehyde solution, 1.5 parts of pyrophosphate tetrasodium salt and 20 parts of water are added and the pH is adjusted to 3.5 with 11.5 parts of lithium hydroxymonohydrate. The temperature of the reaction mixture should not rise above 70 ° C. The solution obtained is acidified with 20.9 parts of 75% acetic acid (total residue about 57%).

If the procedure is as described in Examples 1, 2 and 4, but if the condensation products (II), (IV), (V) and (VII) to (X) are used, the corresponding lithium salts are obtained.

Application examples Example A

100 parts of decalcified veal pellet are treated with 150 parts of water and 51 parts of the composition prepared according to Example 1 for 24 hours at 20 ° C. in a rolling barrel. After washing, greasing, stretching, drying, conditioning, cleats and stretching, you get a white tanned leather that has a full grain and a soft feel.

Example B

100 parts of folded chrome grain calf leather are treated with 150 parts of water and 10 parts of the composition prepared according to Example 3 for 2 hours at 50 ° C. in a rolling barrel. After washing, the leather is neutralized with sodium formate and sodium bicarbonate according to customary methods, washed, with 1 part of the leather dye C.I. Acid Brown 189 colored and aftertreated with a commercially available fatliquor based on sulfonated fish oil. After completion of the leather as indicated in Example A, a retanned, brown-colored, brilliant leather is obtained, which also has a full grain and a soft handle.

Example C

100 parts of polyamide carpet are made up of an aqueous solution at 60 ° C
5 parts of the lithium salt prepared according to Example 4,
1 part of magnesium sulfate and
5 parts of ammonium acetate, which was adjusted to pH 2.5 with formic acid,
Treated for 15 minutes. The treated carpet is then rinsed with cold water and dried. The treated carpet shows no affinity at room temperature for CI FD&C Red 40.

Example D

100 g of a polyamide 6,6 tricot are placed in a dyeing machine at 40 ° C. in a liquor (liquor ratio 1:40) which contains 2 g of a commercially available anionic leveling agent and 1.2 g of a dye and is adjusted to pH 5 with acetic acid is. The dye bath is heated to 98 ° C. in the course of 30 minutes while the liquor is in constant circulation, and dyeing is carried out at this temperature for 30 minutes. The dye bath is then cooled and the substrate rinsed. The substrate is then introduced at 70 ° C. into a liquor (liquor ratio 1:40) which contains 3 g of the condensation product of 4,4'-dihydroxydiphenyl sulfone and sulfonated phenol with formaldehyde and is adjusted to pH 4 with acetic acid. The substrate is treated at 70 ° C. for 15 minutes and then the bath is cooled. The substrate is rinsed and dried. The jersey obtained has improved wet fastness.

Claims (9)

1. A process for tanning hides or for retanning leather using synthetic tanning agents, which comprises treating the hides or the leather in a conventional manner with an aqueous solution of a synthetic tanning agent comprising

   (A) a lithium salt of a synthetic, anionic aromatic tanning agent selected from the group consisting of

   (I) condensates of sulfonated phenol or cresol and formaldehyde,

   (II) condensates of naphthalenesulfonic acid and formaldehyde,

   (III) formaldehyde condensates of 4,4'-dihydroxydiphenyl sulfones with (hydroxy)arylsulfonic acids,

   (IV) formaldehyde condensates of sulfonated aromatic hydroxy compounds with aralkyl halides,

   (V) urea/formaldehyde condensates of phenols and phenolsulfonic acids,

   (VI) reaction products of phenol and a sulfonating agent in which the molar ratio of (phenol): (SO₃) is (1): (1.1-2.2),

   (VII) condensates of sulfonated diaryl ethers and formaldehyde,

   (VIII) condensates of sulfonated diphenyls or terphenyls and formaldehyde,

   (IX) condensates of 4,4'-dihydroxydiphenyl sulfone and sulfonated 4,4'-dihydroxydiphenyl sulfone with formaldehyde, and

   (X) formaldehyde condensates of diaryl ether sulfonic acid and 4,4'-dihydroxydiphenyl sulfone, and, as optional components,

   (B) a water-soluble chromium, aluminium, iron or zirconium salt or a mixture thereof, and

   (C) an alkali metal salt of ethylenediaminetetraacetic acid or of a pyrophosphate.
2. A process according to claim 1, in which component (B) is a basic chromium(III) chloride or basic chromium(III) sulfate, a chrome alum, basic or acidic aluminium chloride or sulfate, an alum, iron(III) chloride or iron(III) sulfate, zirconium oxychloride or basic or acidic zirconium sulfate or a mixture of said chromium or aluminium salts.
3. A process according to claim 2, in which component (B) is [CrCl₂(OH₂)₄]Cl·2 H₂O, [Cr(OH₂)₆]Cl₃, Cr(OH)SO₄, Cr₂(OH)₄SO₄, KCr(SO₄)₂·12 H₂O, AlCl₃·6 H₂O, Al₂(SO₄)₃·16 H₂O, Al₂(OH)₄SO₄, Al(OH)₂Cl, Al(OH)Cl₂, KAl(SO₄)₂·12 H₂O, Fe₂(SO₄)₃·9 H₂O, Zr(OH)₂SO₄, ZrOCl₂·8 H₂O and Zr(SO₄)₂·4 H₂O.
4. A process according to claim 1, in which component (C) is the tetrasodium salt of ethylenediaminetetraacetic acid or neutral or acid sodium pyrophosphate.
5. A process according to claim 1, which comprises the use of
   5 to 60 % by weight of component (A),
   0 to 60 % by weight of component (B),
   0 to 60 % by weight of component (C), and
   water to make up 100 % by weight.
6. A process for protecting polyamide fibre material against stains, which comprises applying a lithium salt of a synthetic anionic aromatic tanning agent selected from the group consisting of the compounds I to X defined in claim 1 to the fibres.
7. A process for enhancing the wetfastness properties of dyeings on polyamide fibres, which comprises treating the dyed fibres with a lithium salt of a synthetic anionic aromatic tanning agent selected from the group consisting of the compounds I to X defined in claim 1.