JPS6318640B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses mineral tanned leather, especially tanned leather tanned with chrome tanning agent, using the general formula In the formula, R is a group

【formula】

[expression] or

[Formula], R ₁ represents hydrogen or methyl, X represents hydrogen, an alkali metal ion, especially a sodium or potassium ion, or an ammonium ion, n represents a number from 1 to 4, and in the formula, SO ₃ relates to a method of retanning using sulfonic acid and its salts, which are combined with phenyl. Preference is given to using the mono- and di-sulfonic acid isomers of diphenyl, terphenyl, diphenyl ether and ditolyl ether and their alkali metal and ammonium salts. The use of other non-crosslinked aromatic hydrocarbon sulfonic acids in various operations in the manufacture of tanned leather, for example their use of naphthalene and toluene as auxiliaries for deliming rawhide (Pelts) (British Patent No. 8096) ) or their use in tanning in the form of Cr() salts (German Patents No. 627110 and No. 643088) is already known. Alkali metal salts of benzene and naphthalene mono- and di-sulfonic acids have also already been proposed for improving the preservation and storage stability in wet or dry conditions of mineral-tanned, undyed leather (German patent no. No. 578578). In addition, a non-swelling acid (non-bleaching acid) is used to acid-treat the hide before tanning.
The use of aromatic sulfonic acids as plumping acids belongs to the state of the art (Ullmanns Enzyklopa″die der
4th edition, Vol. 16, p. 120). Examples of substances commonly used as retanning agents and auxiliaries for homogenizing chemical and/or physical irregularities on the surface of tanned leather are β-naphthalene sulfonic acid (German Patent No. 290 965), diphenyl ether - and ditolyl ether-formaldehyde condensation products of sulfonic acid (US Pat. No. 2,315,951) and terphenylsulfonic acid (US Pat. No. 3,906,037) and their ammonium or alkali metal salts. are mainly phenolic-containing formaldehyde condensation products of aromatic sulfonic acids or in the form of their salts;
So-called displacement tanning agents are also commonly used in practice as retanning and/or homogenizing agents for chrome-tanned leather (UK Patent No. 1291784 and German Patent No. 611671). The disadvantage of these high molecular weight anionic retanning agents and homogenizing agents is that when coexisting with anionic dyes, they are selectively absorbed onto the surface of the leather, preventing the possibility of binding of the anionic dyes here. This inevitably causes the dye to become more deeply fixed within the leather. Very uniform surface dyeings are indeed obtained in this way, but they are significantly lighter than the dyeings obtained without anionic homogenizers. Only some of the available dyes are used for surface staining.
If very uniform dyeings are required, it has hitherto had to be accepted that anionic retanning agents and leveling agents also result in a loss of color intensity. There are in fact increasingly different differences between the various types of tanning and homogenizing agents in their lightening effect on dyeings, and these depend, among other things, on the ratio of homogenizing agent or retanning agent to dye; Invariably, they cause a significant loss of color intensity on tanned hides, which is 50 It can reach ~80%. If, in order to produce deeper dyeings on highly retanned leather, the charge on the surface of the tanned leather is changed to a cationic charge by means of cationic auxiliaries or mineral tanning agents before dyeing, anionic tanning agents, retanning agents, etc. Defects similar to those observed when dyeing pure tanned leather that has not been treated with tanning or homogenizing agents are often present in homogeneity. Surprisingly, sulfonic acids of formula () and their salts, which have not been condensed with formaldehyde to give larger molecules, as is the case with anionic synthetic tanning agents and homogenizing agents, are eminently suitable as retanning agents. was found. They offer the advantage of producing extremely homogeneous, deep, bright surface dyeings using anionic dyes on leather retanned with these compounds or treated before or during dyeing. The color intensity obtained is similar to that obtained with pure chrome-tanned leather without treatment with retanning and/or homogenizing agents. Preferred and suitable retanning agents of the formula (), which together with optimal utilization of the available dyestuffs enable deep and light dyeing of the leather, are sodium hydroxide or, because of its better solubility, preferably ammonia. A mixture of terphenyl mono- or di-sulfonic acids partially or completely neutralized with They are for example US patents
3906037, Example 3, columns 44-54, 1 mole of the technical terphenyl isomer mixture is sulfonated with 2 moles of sulfuric acid-hydrate at 145-150° C. for 2 hours, and the reaction mixture is subsequently sulfonated. It can be produced by neutralizing to the desired final PH value and converting the product to a powder by spray drying. The technical isomer mixture of terphenyl, which is unavoidably obtained as a by-product in the synthesis of diphenyl from benzene, is a suitable and particularly economical starting material for the preparation of such terphenyl sulfonic acid mixtures. The sulfonic acids of formula () and their salts can be added in an amount of 2 to 10% before or during dyeing with anionic dyes,
It has an optimal effect with respect to the homogeneity, gloss and intensity of the dyeing of the leather when it is applied and absorbed into the tanned leather, preferably in amounts of 3 to 6% (based on the so-called depilated weight of the hide). They exhibit a particularly good homogenizing effect on dyeings if they are applied to the leather before the addition of the dye and the dye can be absorbed uniformly into the homogenized leather. They compensate for the differential staining of damaged and undamaged areas within individual fur or hides. The compounds of formula () can also be used on leather in combination with other tanning agents and auxiliaries. For example, they can be combined with chrome tanning agents, which actually increase the swelling properties and are often used with synthetic tanning agents for retanning to enhance the properties of the leather. Basifying agents and/or neutralizing agents such as, for example, sodium sulfite, sodium carbonate, or alkali metal or alkaline earth metal salts of organic carboxylic acids, such as, for example, formic acid, acetic acid or technical dicarboxylic acid mixtures, may also be used for chromium It can be suitably added to the combination in an amount commensurate with the proportion of the tanning agent. If, for example, improvement in the swelling and softness of tanned leather and at the same time good dyeability are required, the following 33% basic chromium sulfate, 40 to 80 parts by weight, terphenyl obtained from a mixture of industrial terphenyl isomers, 40-20 parts by weight of sodium salts of mono- and di-sulfonic acid mixtures and sodium sulfite
A combination of 20 to 0 parts by weight has been found to be suitable. Sodium or ammonium salts of mono- and di-sulfonic acids of the terphenyl isomer mixture obtained from the synthesis of aromatic sulfonic acids of the above formula, preferably diphenyl - alkali metal salts of basic or polybasic organic acids or 70 to 40 parts by weight of sodium salts of industrial dicarboxylic acid mixtures, which are inevitably obtained as by-products in the production of adipic acid, with alkaline earth metal salts, and mono- and Mixtures consisting of 30 to 60 parts by weight of sodium and/or ammonium salts of di-sulfonic acid mixtures have also proven particularly suitable for simultaneous neutralization and retanning for homogenization purposes. In the following examples, unless stated otherwise, the % data relate to the depilated weight of the chrome-tanned leather. Example 1 1.6 to 1.8 produced by conventional methods in industry
Chrome-tanned leather from cowhide or calfskin that has been warped to mm and neutralized to pH 3.8 to 4.2 is processed in a rotating tanning drum.
Terphenyls mono- and - using 100% bath
Treat with 6% mixture of ammonium salts of di-sulfonic acids. The mixture has an acid value (KOHmg/
g) had been adjusted to 40, 2.4 mol of sulfuric acid-hydrate were allowed to act on the technical terphenyl isomer mixture from the synthesis of diphenyl for 3 hours at 150°C, and after cooling and dilution the product was treated with ammonia. Produced when neutralized to an acid value of 40 and spray dried. After the leather has been pretreated in this way, it is dyed in a manner customary in the industry with 1% of the copper complex of the monoazo dye from German Patent No. 670 935, Example 1. After dyeing, the tanned leather is emulsified in a dyebath in an industrially customary manner and then post-treated with 1.5% formic acid in order to achieve the best possible absorption of dyestuff and emulsion fatliquor. After drying and stretching the tanned leather, a plump, soft tanned leather is obtained which is very shiny and has a deep express dyeing. The color intensity of this tanned leather corresponds to that of a tanned leather that has been dyed with the same amount of dye but not pretreated with auxiliaries, and as a result has a much lower homogeneity. Terphenylsulfonic acid/formaldehyde condensate prepared according to U.S. Pat. No. 3,906,037, Example 3 in place of terphenylsulfonate
Chrome-tanned leather treated under the same conditions with Na salts shows a light staining with a marked shine. Example 2 Chrome-tanned cowhide leather, made to a thickness of 1.6 to 1.8 mm and neutralized to a pH of 3.6 to 3.8, was treated with the sodium salt of diphenyl ether-disulfonic acid 4 at 40°C in a 100% solution using methods customary in industry. % for 10 minutes to start retanning. sodium·
To prepare diphenyl ether-disulfonate, 2.4 moles of sulfuric acid-hydrate are allowed to react with 1 mole of diphenyl ether at 120°C for 2 hours with vigorous stirring, the mixture is cooled, diluted and hydroxylated. Neutralize with sodium solution and convert to powder form by spray drying. After the above treatment, an intense retanning is then carried out in the same bath with in each case 2% of a phenolic tanning agent, a resin tanning agent based on dicyandiamide and a vegetable tanning agent, preferably mimosa extract. After 45 minutes, the tanning agent has been completely absorbed and the solution can be drained. The dyeing is then carried out in a fresh solution and in a manner customary in industry using the anionic metal complex dye Acid Brown 85 (CI34900) 2%
Do it using. The emulsion fatliquor and further finishing are likewise carried out in the manner customary in industry. The resulting tanned leather exhibits a plump, glossy, uniform, homogeneous dyeing in the characteristics of flank tanned leather. The dyeability, especially the improvement of color intensity, gloss and homogeneity, can be improved using the method described in U.S. Pat. No. 2,315,951, Example 1.
This will become particularly clear if a comparative example is carried out in which the condensation product of diphenyl ether-sulfonic acid and formaldehyde obtained by is used instead of the sodium salt of diphenyl ether-sulfonic acid. Example 3 In order to produce Nubuku tanned leather, chrome tanned leather which had been warped in a conventional manner in the industry and neutralized to PH6.0 (partially dyed with bromothymol blue, from yellow to yellow-green) was first heated in a manner conventional in the industry at 40°C.
Wash with 300% water at 300°C. After shaking off the washing liquid, the leather is pre-emulsified with 2.5% of a sulfite emulsified fatliquor based on whale oil in a 100% solution at 40°C for 15 minutes, then NH in the same solution. ₃ 10 by 1% ammonia solution containing 2.5% by weight
Process for minutes. Next, 2.5% of the anionic metal complex dye Acid Brown 85 (CI34900) and 2% of the potassium salt of o-terphenyl-4,4′,4″-trisulfonic acid and 2% of the Japanese oak extract with the addition of sugar.
is added, and dyeing and retanning are carried out simultaneously for 90 minutes. After this treatment, add 100% water at 70℃ and let it act for 10 minutes, then pure formic acid 8.5% by weight in the same solution.
Acidify the tanned leather for 40 min using a formic acid solution containing 1.5% (up to PH 3.8). After shaking off the solution, the tanned leather is coated with an additional 1.5 ml of the same dye as the pre-treatment.
% in a fresh bath in a solution 100% at 55° C. and then emulsified fatliquing with a milky fatliquing mixture based on wool fat and chloroparaffin sulphonates. Finally, the tanned leather is post-treated with 2.5% of sugared oak tree extract and acidified once again with a 0.5% formic acid solution containing 8.5% by weight of pure formic acid.
Tanned leather is washed in the usual way in the industry and
Set the pH value to 3.8 and place it on the stand overnight. Deflate, 50
After vacuum drying for 1/2 min at 80 °C under reverse pressure of
The leather is hung to dry, conditioned, tied, and vacuum dried again at 80-90°C for 1/2 minute. The grain side is then polished 3-4 times with 220-230 abrasive paper at a residual moisture content of 18-20%, depending on the nature of the grain. A plump, soft nubuk-tanned leather results from this operation, which is characterized by high gloss, uniformity of dyeing and a very fine and uniform polish. o-terphenyl-4,4′,4″-trisulfonic acid is in each case o-terphenyl (purity approx. 95
%) with 1500 g of sulfuric acid-hydrate at 110°C for 90 minutes and converting the product to the potassium salt with potassium chloride (Journal of Organic Chemistry).
Organic Chemistry), vol. 14, p. 163 (1949)).

Claims (1)

[Claims] 1. In the re-tanning of mineral-tanned leather, the general formula In the formula, R is a group [Formula] [Formula] or [Formula] R ₁ represents hydrogen or methyl, X represents hydrogen, an alkali metal ion, or an ammonium ion, n represents a number from 1 to 4, and in the formula A method characterized in that sulfonic acids and their salts are used as retanning agents, SO ₃ 2 Diphenyl, terphenyl, completely or partially neutralized with alkali or ammonia,
2. Process according to claim 1, characterized in that a salt of a mono- and di-sulfonic acid mixture of diphenyl ether or ditolyl ether is used as retanning agent. 3. Claim 2, characterized in that mono- and di-sulfonic acid mixtures of isomers of terphenyl, completely or partially neutralized with alkali or ammonia, are used as retanning agents.
The method described in section. 4 Sulfuric acid 1 at 110-180°C, completely or partially neutralized with alkali or ammonia.
A sulfonic acid mixture of the technical isomer mixture of terphenyl from the synthesis of diphenyl, obtained by acting on 1 mole of terphenyl with 2 to 2.5 mol of hydrate, preferably for a period of 3 hours, is used as a retanning agent. A method according to claim 1, characterized in that: