EP1421223A1

EP1421223A1 - Method for producing tanning agents containing sulphone

Info

Publication number: EP1421223A1
Application number: EP02794798A
Authority: EP
Inventors: Gunther Pabst; Gerhard Wolf; Jürgen Kast; Jürgen Werner
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2001-08-17
Filing date: 2002-08-16
Publication date: 2004-05-26
Also published as: BR0211707A; US6881356B2; WO2003016578A1; DE10140551A1; CN1220781C; US20040250353A1; CN1543511A

Abstract

The invention relates to a method for producing a solution of tanning agents containing sulphone. In said method, a) a component A is produced as follows: a1) phenol is reacted with concentrated sulphuric acid or with oleum with an SO3 content of between 20 and 65 wt. %, or with a mixture of sulphuric acid and oleum with an SO3 content of between 20 and 65 wt. %, whereby the molar ratio of total sulphuric acid, calculated in the form of SO3 to phenol is between 0.7: 1 and 1.5: 1, at a temperature of between 100 and 180 °C to obtain a mixture containing phenolsulphonic acid, dihydroxydiphenyl sulphone and sulphuric acid, or the individual components are blended to produce a corresponding mixture; a2) said mixture is subsequently condensed at between 40 and 90 °C per mol of phenol units present with between 0.25 and 4 mol of urea and between 0.5 and 4 mol of an aliphatic aldehyde comprising between 1 and 6 C atoms, a3) optionally a pH value of between 4 and 5 is set by adding a base; b) a component B is produced as follows: b1) dihydroxydiphenyl sulphone is reacted with between 0.5 and 5 mol of an aliphatic aldehyde comprising between 1 and 6 C atoms and between 0.4 and 2 mol of sodium sulphite per mol of dihydroxydiphenyl sulphone, at a temperature of between 90 and 180 °C; b2) optionally a pH value of between 3.5 and 5.5 is set by adding an acid. c) Between 10 and 90 wt. % of component A is mixed with between 90 and 10 wt. % of component B, (the sum of A and B amounting to 100 wt. %) and if not already accomplished in steps a3) and b2), the pH value of the mixture is set at between 3.5 and 5.5.

Description

Process for the production of tannins containing sulfones

The invention relates to a method for producing a solution of sulfone-containing tannins, the solution itself obtainable by this method, the sulfone-containing tannin isolated from this solution, the use of the solution and the sulfone-containing tannin for tanning leather, a method for tanning leather and the tanned one Leather itself.

Condensation products based on dihydroxydiphenyl sulfone are known for example from DE-B 11 13 457, EP-A 0 245 205, EP-B 0 428 481, US 4,592,940 and EP-B 0 459 168 and can be prepared by the processes described therein.

According to DE-B 11 13 457, sulfonated phenols which are free of condensed ring systems are reacted with 1 to 1.5 mol of urea and 1.7 to 2.2 mol of formaldehyde per mol of the sulfonated phenol or phenol mixture and the condensate obtained is reacted with phenol and treated with formaldehyde.

EP-A 0 245 205 relates to an aqueous composition containing a reaction product of phenol and a sulfonating agent, the molar ratio of phenol: SO _{3 being} 1: 1.1-2.2, a water-soluble alkylamine, alkanolamine, alkylenediamine, polyalkylene polyamine or hetrocyclic amine , a water-soluble chromium, aluminum, iron or zirconium tanning salt and optionally an alkali metal salt of ethylenediaminetetraacetic acid or a pyrophosphate.

EP-A 0 428 481 discloses an agent for the treatment of leather and furs, containing as component (A) formaldehyde condensation products of 4,4'-dihydroxydiphenyl sulfones with hydroxyarylsulfonic acids or formaldehyde condensation products of diaryl ether sulfonic acids with 4,4'-dihydroxydiphenyl sulfone, and as component (B) a polymer or copolymer of unsaturated C ₃ -C ₅ mono- or dicarboxylic acids or of their hydroxy compounds. No. 4,592,940 discloses a process for the dirt-repellent finishing of nylon carpets, in which they are treated with an aqueous solution of a condensation product of formaldehyde with a mixture of diphenyl sulfone and phenol sulfonic acid.

EP-A 0 459 168 discloses condensation products of phenol monosulfonic acids, dihydroxydiphenyl sulfones, urea and formaldehyde, which are obtainable by

A) heating phenol with concentrated sulfuric acid, with oleum or with a mixture of sulfuric acid and oleum to 100 to 180 ° C., the molar ratio of phenol to total sulfuric acid, calculated as SO ₃ , being 1 to 1.2: 1,

B) then precondensed at 40 to 90 ° C. per mole of phenol units present with 1 to 2 moles of formaldehyde and 0.5 to 1.5 moles of urea in an aqueous medium,

C) the reaction mixture is partially neutralized,

D) the partially neutralized reaction mixture is mixed with 0 to 0.5 mol of phenol per mol of phenol units present and 0.1 to 0.8 mol of formaldehyde per mol of the phenol units present thereafter,

E) post-condensed at 40 to 90 ° C,

F) shifts the pH of the reaction mixture into the neutral range and

G) then acidified with a weak acid.

The condensation products are used for tanning animal hides.

As is known to the person skilled in the art, tanning agents which are produced using dihydroxydiphenyl sulfone (DHDPS) are distinguished by a particularly good tanning action and by particularly good fastness properties. When using tannins with a high DHDPS content, negative effects of this tanning effect can also be observed on leather. Too high an astringency can lead to the scars of the leather being stressed too much and therefore being associated with it Scarring is observed. The stress on the grain can lead to breakage of the grain, which causes a significant reduction in the quality of the leather. The superficial deposition of strongly astringent tannins also leads to a reduced penetration not only of the tannins used, but also of all other aids. In addition, it is observed that the strong astringency of sulfone-containing tanning agents leads to a strong bleaching effect, making dark, intensely colored leather in particular difficult to produce.

On the other hand, if you look at tannins with a low DHDPS content, you will notice that their tanning effect and thus the stabilization of the collagen fiber is often too low. However, a good tanning effect is important in so-called wet white leathers, since the tanning effect of the synthetic tanning agents used is decisive here because the chromium does not have a tanning effect. To a certain extent, the tanning effect of the synthetic tanning agents can be controlled via their molecular weight, but the more tanning agents with higher molecular weight are a disadvantage of a reduced penetration of the tanning agents into the leather cross-section and thus an undesirable superficial deposition of the tanning agents. In addition, the leather treated with tannins with a low DHDPS content generally has less good fastness properties.

The object of the invention is to provide new tanning agents with advantageous properties. The object of the invention is in particular to provide tanning agents with a good tanning effect and good penetration, which give leather with good fastness properties, softness and fullness.

The object is achieved by a process for producing a solution of sulfone-containing tannins, in which

a) a component is produced by al) phenol with concentrated sulfuric acid, with oleum having an SO ₃ content of 20 to 65% by weight or with a mixture of sulfuric acid and oleum having an SO ₃ content of 20 to 65% by weight. -%, the molar ratio of total sulfuric acid, calculated as SO ₃ , to phenol from 0.7: 1 to 1.5: 1, at a temperature of 100 to 180 ° C to a mixture containing phenolsulfonic acid, dihydroxydiphenyl sulfone and sulfuric acid can react, or by mixing the individual components produces a corresponding mixture, a2) then at 40 to 90 ° C per mole of phenol units present with 0.25 to 4 moles of urea and with 0.5 to 4 moles of an aliphatic aldehyde with 1 to 6 C atoms condense, a3) if necessary by adding a base to a pH of 4 to 5,

b) a component B is prepared by reacting bl) dihydroxydiphenyl sulfone with 0.5 to 5 moles of an aliphatic aldehyde with 1 to 6 carbon atoms and 0.4 to 2 moles of sodium sulfite per mole of dihydroxydiphenyl sulfone at a temperature of 90 to 180 ° C. b2) adjusts a pH of 3.5 to 5.5 if necessary by adding acid,

c) 10 to 90% by weight of component A with 90 to 10% by weight of component B, the sum of A and B being 100% by weight, mixed and, if not already carried out in steps a3) and b2) , adjust the pH of the mixture to 3.5 to 5.5.

Surprisingly, it was found that when tanning agents with a low DHDPS component (component A) are mixed with tanning agents with a high DHDPS component (component B), the tanning effect of the tanning agents with a high DHDPS component is retained, but at the same time a good penetration of the tanning agent mixture is achieved becomes. This avoids superficial deposition of the tanning agent on the leather. On the one hand, this results in considerable advantages in terms of coloring. The surface is colored more intensely and darker, and at the same time the leather cross-section is well colored. This enables savings to be achieved in the dye used, which also improves economy. On the other hand, a scarring or a scarring of the leather is prevented, and the uniformity of the mill fracture is improved. Although the process according to the invention starts from starting materials known per se for producing sulfone-containing tanning agents, the new reaction sequence and the new quantitative ratio of the starting materials lead to products with improved performance properties. The invention thus also relates to the solutions of sulfone-containing tannins obtained by the process according to the invention and the sulfone-containing tannins themselves which can be isolated therefrom.

The aliphatic aldehydes used in the production of component A and component B generally have 1 to 6, preferably 1 to 4 and particularly preferably 1 or 2, carbon atoms. In particular, formaldehyde is used as the aliphatic aldehyde, usually in the form of an aqueous solution, for example in the form of a 30% by weight aqueous solution.

In the preparation of component A, phenol is concentrated with concentrated sulfuric acid, preferably 96% by weight, and / or oleum with an SO ₃ content of 20 to 65% by weight

100 to 180 ° C over a period of generally 1 to 10, preferably 3 to 6

Reacted for hours, the molar ratio of total sulfuric acid, calculated as

SO ₃ , to phenol from 0.7: 1 to 1.5: 1, preferably from 0.8: 1 to 1.2: 1, particularly preferably from 0.9: 1 to 1.1: 1 and in particular 1: 1 is. This forms phenol monosulfonic acid and dihydroxydiphenyl sulfones (4,4'-, 2,4'- and 2,2'-isomers). In addition, minor quantities of by-products such as higher

Condensation products formed from SO ₃ and phenol (trimers, tetramers).

Of course, instead of the in situ sulfonation, a correspondingly composed phenol monosulfonic acid / dihydroxydiphenyl sulfone / sulfuric acid mixture can also be prepared by mixing the corresponding components.

The exact composition of the reaction mixture obtained in step a1) can be determined, for example, by high pressure liquid chromatography. The amount of dihydroxydiphenyl sulfones formed in situ is influenced in particular by the reaction temperature and by the SO ₃ content of the reaction mixture. The reaction is preferably carried out with oleum having an SO ₃ content of 20 to 32% by weight at a temperature of 150 to 180 ° C. To prepare the mixture of phenol and concentrated sulfuric acid and / or oleum to be heated to 100 to 180 ° C., the acids are expediently continuously dripped into a phenol heated to approximately 60 ° C., heating to approximately 90 to 100 ° C. , If necessary, the temperature can be regulated by cooling. In a subsequent step a2), the mixture of phenolsulfonic acid, dihydroxydiphenyl sulfone and sulfuric acid at 40 to 90 ° C, for example at about 80 ° C, with 0.25 to 4 mol, preferably 0.4 to 0.8 mol of urea and 0.5 to 4 moles, preferably 0.75 to 1.5 moles, of an aliphatic aldehyde, in particular formaldehyde, condensed per mole of phenol units present. Urea is usually added as an aqueous solution, for example as a 68% strength by weight aqueous solution, and the aldehyde is then metered in over a period of generally 0.25 to 8, preferably 0.25 to 2, hours.

A pH of 3.5 to 5.5, preferably 4 to 5, particularly preferably 4.3 to 4.8 and in particular 4.4 to 4.6 can then be set in step a3). The pH can be adjusted by adding a commercially available base, such as alkali metal hydroxide or ammonia. It can also be neutralized first by adding a base and then by adding a weak acid, for example acetic acid, formic acid, oxalic acid, succinic acid, glutaric acid or citric acid, to adjust the pH to 3.5 to 5.5.

Component A thus prepared generally contains 2 to 30, preferably 5 to 15% by weight of dihydroxydiphenyl sulfone in free or bound form, based on the dry weight.

In the preparation of component B, di) hydroxydiphenyl sulfone with 0.5 to 5 mol, preferably 1 to 1.4 mol, particularly preferably 1.1 to 1.3 mol and in particular approximately 1.2 mol of an aliphatic aldehyde is used in a step b1) , in particular formaldehyde, per mole of dihydroxydiphenyl sulfone and 0.4 to 2 moles, preferably 0.5 to 0.8 moles, in particular 0.6 to 0.7 moles of sodium sulfite per mole of dihydroxydiphenyl sulfone, at a temperature of 90 to 180 ° C. The reaction is usually carried out in aqueous solution under pressure. For example, dihydroxydiphenyl sulfone and formaldehyde in the form of their aqueous solutions and solid sodium sulfite are placed in a pressure reactor and the mixture is heated to 115.degree. After the reaction has started, the temperature rises to about 150 to 160 ° C. and the pressure to about 4 to 5 bar. The reaction generally takes 2 to 10 hours. Dihydroxydiphenyl sulfone in the sense of this invention means the 4,4'-isomer. This can also be used as technical dihydroxydiphenyl sulfone, ie in a mixture with about 10-15% by weight of the 2,4'-isomer and 0 to 5% by weight of p-phenolsulfonic acid. In a step b2), the pH of component B can then be adjusted to 3.5 to 5.5, preferably 4 to 5, particularly preferably 4.3 to 4.8 and in particular 4.4 to 4.6. The pH can be adjusted by adding acid such as sulfuric acid, formic acid or acetic acid.

In general, the content of component B in dihydroxydiphenyl sulfone in free or bound form is from 30 to 100% by weight, preferably from 40 to 70% by weight, particularly preferably from 45 to 55% by weight, based on the dry weight.

In a step c) 10 to 90% by weight, preferably 20 to 80% by weight, particularly preferably 30 to 70% by weight of component A are mixed with 90 to 10% by weight, preferably 80 to 20% by weight. %, particularly preferably 70 to 30% by weight of component B, the sum of A and B giving 100% by weight. If the pH has not already been set in components A and B, it is now carried out in the mixture of A and B using the acids or bases mentioned above.

The solution of the sulfone-containing tanning agents thus obtained can be used directly as a tanning agent. However, it is also possible to isolate the sulfone-containing tannin from this solution. The isolation can be carried out in a manner known per se, for example by precipitation of the tanning agent by adding a water-miscible liquid in which the tanning agent does not dissolve, or preferably by evaporating the liquid reaction medium, for example by spray drying. The tannin is usually isolated for shipping purposes. Before use, the solid sulfonic tanning agent is redissolved in water.

The present invention also relates to the use of the solutions according to the invention and the sulfone-containing tannins which can be isolated therefrom for tanning leather.

The invention also relates to a process for tanning leather, in which the leather is treated with an aqueous solution of the sulfone-containing tanning agent according to the invention. Commercially available dispersants, in particular anionic dispersants, and / or commercially available synthetic, polymeric and / or vegetable tannins can also be used in the application. This creates special effects on the treated leather. In view of the new combination of advantageous properties of the leather treated using the tanning agents according to the invention, the treated leather itself is also an object of the present invention.

The invention is illustrated by the following examples.

Examples

Example 1:

Preparation of component A

40 kmol of phenol heated to 60 ° C. are mixed with 40 kmol of oleum with an SO ₃ content of 24% by weight within one hour. The mixture obtained is heated to 160 ° C. and stirred at this temperature for 4 hours. The mixture is then allowed to cool to 80 ° C. and 25 kmol of urea are stirred in as a 68% strength by weight aqueous solution and 40 kmol of formaldehyde are then metered in as a 30% strength by weight aqueous solution within 1 1/2 hours. The mixture obtained is then mixed with about 34 kmol NaOH in the form of a 50% strength by weight aqueous solution, a pH of 4.5 being established.

The content of dihydroxydiphenyl sulfone is 10% by weight, based on the dry weight.

Example 2:

Production of component B

In a pressure reactor 10 kmol technical dihydroxydiphenyl sulfone (containing 80 wt .-% of the 4,4'-isomer and about 10 to 15 wt .-% of the 2,4'-isomer and small amounts of p-phenolsulfonic acid) as 60 wt. -% aqueous solution submitted and 12 kmol of formaldehyde as 30 wt .-% aqueous solution and 6.5 kmol of solid sodium sulfide added. The pressure reactor is closed and the mixture heated to 115 ° C. The temperature then rises to approx. 150 to 160 ° C and the pressure to 4 to 5 bar. After stirring for 3 hours at 160 ° C., the solution obtained is cooled and the pH is adjusted to 4.5 by adding formic acid. The content of dihydroxydiphenyl sulfone is 50% by weight, based on the dry weight.

Example 3:

1: 1 mixture of components A and B (product C)

50 parts by weight of component A, in which the pH has not yet been adjusted by adding sodium hydroxide solution, are mixed with 50 parts by weight of component B, in which the pH has not yet been adjusted by adding formic acid, and 4 hours homogenized for a long time. A pH of 4.5 is then set by adding formic acid and the mixture is diluted with 5 parts by weight of water.

The content of dihydroxydiphenyl sulfone is 30% by weight, based on the dry weight.

Example 4:

Preparation of a 3: 7 mixture of components A and B (product D)

The procedure is as in Example 3, but 30 parts by weight of component A are mixed with 70 parts by weight of component B.

The content of dihydroxydiphenyl sulfone is 42% by weight, based on the dry weight.

Example 5:

Use of components A and B (comparison) and products C and D (according to the invention) as sole genetics

The following percentages relate to the weight of the bladders. A custom-made pickled beef blotch (gap thickness 3 mm) is mixed with 25% tannin in the tanning drum in 75% water and agitated at a pH value between 3.0 and 4.0 for 10 hours in a normal working drum. The liquor is removed and drummed with 50% water and 5% of a commercial fatliquor for 60 minutes. The pH is then adjusted to 3.2-3.5 using dilute formic acid. The leather is stretched, dried, conditioned and stabled. The shrink temperature according to DIN 53336, the light fastness, the fullness and the softness are tested on the leather treated in this way. Lightfastness, fullness and softness are rated on a scale from 1 = very good to 5 = very bad.

The results are summarized in Table 1 below.

Table 1 :

The results show that products C and D with a very good tanning effect (see shrinking temperature) achieve good fullness and good softness at the same time. As is known to the person skilled in the art, the softness depends on the penetration of the tanning agent. The leather treated with component B showed a significant breakage of the grain when subjected to mechanical stress.

Example 6:

Use on wet blue for upper leather

The following percentages relate to the fold weight.

Beetroot blue with a fold thickness of 1.5 mm is rinsed, washed and then washed up in 100% water with a sodium bicarbonate / sodium formate mixture pH 4.4 - 4.6 deacidified. Then retanned in 100% new liquor at 40 ° C with 8% tannin for 90 minutes, rinsed and dyed in 100% water at 50 ° C for 20 minutes as usual. It is then greased with 5% of a commercially available fatliquor for 40 minutes and adjusted to pH 3.6 using formic acid. The depth of color, color, softness, fullness and firmness of the treated leather are rated on a scale from 1 = very good to 5 = very bad.

The results are summarized in Table 2 below.

Table 2

As the results of the table show, the mixtures C and D are superior to the starting components A and B in terms of the entirety of the properties evaluated. In particular, they lead to good coloring in combination with good surface coloring (color depth). This is surprising since the latter two properties are usually opposed. With the mixtures C and D a better fullness and softness are achieved than with the starting components A and B.

Claims

claims

1. A process for producing a solution of sulfonic tannins, in which

a) a component A is prepared by al) phenol with concentrated sulfuric acid, with oleum of a SO ₃ -

Content of 20 to 65 wt .-% or with a mixture of sulfuric acid and oleum with an SO ₃ content of 20 to 65 wt .-%, the molar ratio of total sulfuric acid, calculated as SO ₃ , to phenol from 0.7: 1 to 1.5: 1, at a temperature of 100 to 180 ° C to a mixture containing phenolsulfonic acid,

Dihydroxydiphenylsulfone and sulfuric acid can react, or by mixing the individual components produces a corresponding mixture, a2) then at 40 to 90 ° C per mole of phenol units present with 0.25 to 4 moles of urea and with 0.5 to 4 moles of an aliphatic aldehyde 1 to 6 C atoms are condensed, a3) if necessary by adding a base to a pH of 4 to 5,

b) produces a component B by bl) dihydroxydiphenyl sulfone with 0.5 to 5 mol of an aliphatic

Aldehyde with 1 to 6 carbon atoms and 0.4 to 2 mol sodium sulfite per

Moles of dihydroxydiphenyl sulfone at a temperature of 90 to 180

° C can react, b2) if necessary by adding acid, a pH of 3.5 to

5.5 sets, c) 10 to 90% by weight of component A with 90 to 10% by weight of component B, the sum of A and B being 100% by weight, mixed and, if not already carried out in steps a3) and b2) , adjust the pH of the mixture to 3.5 to 5.5.

2. The method according to claim 1, characterized in that in step al) phenol is reacted with oleum having an SO ₃ content of 20 to 32% by weight at a temperature of 150 to 180 ° C.

3. The method according to claim 1 or 2, characterized in that in step al) the molar ratio of total sulfuric acid to phenol is 0.8: 1 to 1.2: 1.

4. The method according to any one of claims 1 to 3, characterized in that in step a2) 0.4 to 0.8 mol of urea and 0.75 to 1.5 mol of formaldehyde are used per mole of phenol units present.

5. The method according to any one of claims 1 to 4, characterized in that 1 to 1.4 mol of formaldehyde and 0.5 to 0.8 mol of sodium sulfite are used per mole of dihydroxydiphenyl sulfone in step bl).

6. The method according to any one of claims 1 to 5, characterized in that a pH of 4.4 to 4.6 is set in step a3) and b2) or c).

7. Solution of sulfone-containing tannins, producible by the process according to one of claims 1 to 6.

8. The tannin isolable from the solution according to claim 7.

9. Use of the solution according to claim 7 or the sulfone-containing tanning agent according to claim 8 for tanning leather.

10. A method for tanning leather, in which the leather is treated with an aqueous solution of the sulfone-containing tanning agent according to claim 8.

11. Tanned leather, obtainable by the process according to claim 10.