MXPA94006277A - Process for re-tanning tanned leather with chrome - Google Patents

Abstract

La presente invención se refiere a un proceso para recurtir el cuero curtido al cromo, que comprende aplicar al cuero un producto de reacción de:a) al menos un monoéster glicérico de unácido monocarboxílico saturado con 12 a 18átomos de carbono, b) al menos un diisocianato seleccionado del grupo que consiste de toluendiisocianato, hexametilendiisocianato y diisocianato de isoforona, y c)ácido dimetilolpropiónico, en donde:i) los componentes (a), (b) y (c) se seleccionan de tal forma que la relación molar de los grupos isocianato del componente (b) con relación a la suma de los grupos hidroxilo de los componentes (a) más (c) es de aproximadamente 0.5 hasta aproximadamente 1.05, y ii) la relación molar del compuesto (c) al compuesto (a) es de aproximadamente 0.7 hasta aproximadamente 1.5 y en donde, iii) los grupos carboxilo que se originan del compuesto (c) son neutralizados al menos parcialmente.

Description

"PROCESS TO RECOVER THE LEATHER CURTIDO TO THE CHROME" Inventors: HARRO TRAUBEL, German, domiciled at Dresdener Str. 14, 51373 Leverkusen, Germany; WILHELM KRUMMEL, German, domiciled in Strassburger Str. 38, 51375 Leverkusen, Germany and JOACHIM KOCHTA, German, domiciled in Landsberger Str. 69, 53119 Bonn, Germany.

Causaire: BAYER AKTIENGESELLSCHAFT, German company, domiciled at D 51368 Leverkusen, Germany.

$ SUMMARY OF THE INVENTION The present invention relates to a process for retanning chic tanned leathers, which comprises applying to the lees a reaction product of: a) at least one glyceric monaester of a saturated carboxarbaxyl acid with 12 to 18 carbon atoms, b) at least one diisaciapata selected from the rump consisting of taluepdi isociapata, hexamethylepidylisaparate and diisocyanate of isaforana, and c) a41a dimethyl and trifoliate, in dande: i) lc_ components (a), (b) and (c) are selected in such a way that the molar ratio of the isaciapata groups of the component (b) in relation to the sum of the hydroxyl groups of the components (a) plus (c) is from approximately 0.5 to approximately 1.05, and ii) the molar ratio of the compound (c) to compound (a) is from about Q.7 to about 1.5 and wherein, iii) the carboxyl groups that originate from compound (c) are partially neutralized to the ores.

DESCRIPTION OF THE INVENTION The invention relates to the use of certain esterurethanes for the retanning of chrome-tanned leather. "Retanning" refers to the subsequent treatment of pre-tanned leather (usually chrome-tanned), to optimize dyeing, leveling, flexibility, abundance as well as behavior against water (hydrophobicity) and to fix tanning agents. * The most important retanning agents today are in addition to the group of polymeric syntans containing carboxyl groups in the form of salts (EP-A-118 023 and 372 746, DE-OS 39 31 039). However, polyurethanes, which contain, if appropriate, polyethylene oxide groups, ionic groups or methylol groups, have also already been used for retanning (DE-OS 25 04 081). The retanning agents hitherto known do not fulfill all the expectations placed on them, since they either insufficiently waterproof or negatively influence the touch, the dyeability, the looseness of the flower or the subsequent finishing of the leathers. The large number of desirable properties requires commitment. Retanning agents are desired, which provide the leather with an optimum waterproofing (that is, making leather with maintenance of the - i * - water vapor permeability as water-impermeable as possible), but which do not adversely affect the tact, the dyeability, the looseness of the flower and the applicability of the subsequent finish. It has now surprisingly been found that the use of esterurethanes free of polyether groups of a certain composition gives the leather an excellent combination of desirable properties. The object of the invention is therefore a process for using chrome tanned leather, using a reaction product of: a) at least one glyceric monoester of a monocarboxylic acid saturated with 12 to 18 carbon atoms, b) at least a diisocyanate of the series of toluylene diisocyanate, hexamethylene diisocyanate and IPDI (isofor-ondiisocyanate), and c) dimethylolpropionic acid (= 2, 2-bis (hydrox-imethyl) -propionic acid), where the amounts of the components are chosen a) to c) in such a way that the molar ratio of the isocyanate groups of b) to the sum of the hydroxyl groups of a) and c) is from 0.5 to 1.05, preferably from 0.8 to 1.0 and the molar ratio c / aa 0.7 to 1.5, preferably 0.8 to 1.2 m and where the carboxyl groups from c) are at least partially neutralized, for the retanning of chrome tanned leather. The esterurethanes to be used according to the invention can be obtained, for example, in such a way that the glyceric ester a is reacted with the diisocyanate b) and the resulting additive compound with the diol c). The neutralization of the carboxyl groups of c) can be carried out before or after the reaction of c). Suitable neutralizers include, for example, alkali and alkaline earth metal hydroxides, carbonates and hydrogencarbonates, such as sodium hydroxide, potassium hydroxide, sodium carbonate and hydrogencarbonate, potassium carbonate, magnesium, calcium and barium hydroxide, as well as ammonia, primary, secondary and tertiary amines with 1 to 30, preferably 3 to 18 carbon atoms, such as methylamine, ethylamine, n-propylamine, isopropyl-a, n-butylamine, isobutylamine, hexylane, cyclohexylamine, methylcyclohexylamine, 2-ethylhexyl - mine, n-octylamine, isotridecylamine, tallow fatty amine, stearylamine, oleylamine, dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, dihexylamine, dicyclo- * Hexylamine, dimethylcyclohexylamine, di-2-ethylhexylamine, di-n-octylamine, diisotridecylamine, tallow diurea amine, distearylamine, diolethylamine, ethanolamine, diethanolamine, n-propanolamine, di-n-propanolamine and morpholine. Preferably at least 50% and especially at least 80% of the groups are neutralized ^ carboxyl from c). ^ The reactions can be carried out in the absence or in the presence of organic solvents. Preferred organic solvents are inert to the starting compounds used and comprise, for example, acetone, methyl ethyl ketone, tetrahydrofuran, dichloromethane, chloroform, perchlorethylene, ethylacet, dimethylformamide and dimethylsulfoxide. The reaction of compounds a) and b) can § catalyzed by cobalt naphthenate, zinc octoate, preferably dibutyl tin dilaurate or dibutyl tin diacetate, as well as by tertiary amines, such as triethylamine or 1,4-diaza [2. 2.2] -bicyclooctane. The esterurethanes to be used according to the invention can be dispersed in water, for example by adding the neutralizer as an aqueous solution and extracting the organic solvent, if necessary. * existing The esterurethanes are advantageously used as aqueous preparations with an esterurethane content of 1 to 40% by weight in an amount of 0.2 to 10% by weight of solid esterurethane, based on the weight of the recessed leather. The esterurethanes to be used according to the invention are excellently attached to the leather on the leather and make the leather hydrophobic and soft as well as $ solid in the flower without negatively influencing the dyeability. The indications in percentages in the following examples refer respectively to the weight of the lowered leather, the proportions of dilution refer respectively to the weight. All commercial products are (insofar as it is not indicated otherwise) commercial products of the company Bayer AG, Leverkusen. E i e m p l o s Obtaining an esterurethane to be used according to the invention: A 500 ml three-neck round flask, equipped with a stirrer, a reflux condenser with a desiccator tube and a dropping funnel, is used as the apparatus. 17.9 g of monoester are placed in the flask. 0- - ß - glyceric tearate (0.05 mol). One after the other, 45 mg of dibutyl tin diacetate, 50 ml of anhydrous acetone and 14.72 ml (17.9 g) of toluylene-diisocyanate-2.4 / -2.6 (80/20 ratio) are added. , 1028 mol). Now it is heated for 30 minutes until boiling. Subsequently, 11.75 g of the triethylamine salt of 2,2-bis (hydroxymethyl) propionic acid (0.05 mol), dissolved in # 50 ml of anhydrous acetone over the course of 10 minutes. After a reaction time of one hour under reflux, the formation of the esterurethane is completed. The solution is clear, moderately viscous and slightly yellow in color. For the dispersion, 250 ml of deionized water are added dropwise with maintenance of a weak reflux of the acetone. After extraction of the acetone by vacuum distillation, a solution of approximately 17% of the esterurethane results. Example 1 Leather for upholstering wet-blues car seats a) Comparison 2.4 kg of reduced and chrome-tanned leather (recess thickness 1.1 mm) are treated with 250% (based on the weight of the lowered leather) ) of water of 40 ° C, 0.5% aqueous 8.5% formic acid, 0.1% neutral emulsifier (liquid ®Baymol AN, which has been diluted with water in the ratio 1: 5) as well as 2% of a light tanning agent (® Tanigan 3 LN) for 30 minutes. After discharging the bath, it is washed with 300-% water of 40 ° C for 10 minutes and the bath is discharged again. True retanning starts with 150% of * 40 ° C water, 1% of a 33% basic chromium tanning agent (® Chromosal B) as well as 3% of a neutralizing chromium-sintetan mixed tanning agent (®B1- ancorol RC). After 45 minutes 7% of ® Chromopol AFS (Stockhausen) (which has previously been diluted with water in a ratio of 1: 4) is added., it is left to act for 30 minutes and another 1.5% of a neutralizing synthetic tanning agent (Tanigan PAK-N), 4% of a tanner of solid exchange to the light (Tanigan LD-N) and 3% of a resin tanning agent (®Retingan R7) and continue with the treatment for another 15 minutes. In this comparative example, it is now treated with 2% of an acrylate tanning agent (®Baytigan AR, which has been diluted before with water in a ratio of 1: 3) for 45 minutes. The pH value of the bath is thus 5, 3. Then 1.5% sodium formate and 0.5% are added. of sodium carbonate and leave for another 40 minutes (pH value of the bath now 6.1). The crossing of the leather with cresolic chromium green is now blue. It is now discharged for 40 minutes, washed with 300% of water heated at 44 ° C for 10 minutes, unloaded again and now begins with it stained: 30% water is available at 25 ° C and 0.8% of ammonia (25% aqueous solution, which has been previously diluted with water in a ratio of 1: 5) for 5 minutes, a mixture is added, consisting of 2% of an auxiliary light-dispersing solid tanning agent (®Baykanol SL), 3% of a light yellow solid metal complex dye (®Baygenal beige L-NGR) and 0.3% of a light-metal solid complex dye (Baygenal grau L-NG) and leaves react for 30 minutes. Then 10% of Chromopol AFS (which has been diluted before with water in a ratio of 1: 4) is added, after 30 minutes 150% of water of 70 ° C is added, after another 5 minutes again a 2% of Baytig-an AR (which has been diluted before with water in a ratio of 1: 3), after 30 minutes 2.5% of formic acid (85% aqueous solution, which has been diluted in the proportion of 1:10 and 1.25% in two stages), which has been added for 20 minutes ^ (bath pH value now 4.12) and the bath is discharged. Then it is washed again (with 300% water of 40 ° C) and washed after 10 minutes with the lid open with water of 25 ° C for 10 minutes. The leathers are now removed, wetted and dried, heated, screened, milled and expanded and then evaluated. B) According to the invention Instead of the Baytigan AR, the esterurethane to be used according to the invention is used. invention and leaves constant all other parameters of the procedure. The evaluation of both leathers provided: The leather obtained according to the state of the art is not as soft as that according to the invention; the appearance of the flower according to the invention $ tion is clearly better than that according to the state of the art. If a drop of water is applied to the leather according to the state of the art, it immediately sinks into the leather, while penetrating the brown leather according to the invention only after some time slowly at the bottom. E j e m p l o 2 Split leather a) Comparison - • a3fs > a.1-fi? - H '~ v * & They have washed 8 halves of wet-blue with a thickness of 1.3 mm, which have been tanned to chromium, in water of 50 ° C (200%) for 10 minutes and the bath has been discarded. Then 100% (based on the weight of the lowered leather) of water of 40 ° C is added, 2% of a neutralizing synthetic tanning agent (Tanigan PAK-N) as well as 0.5% of sodium bicarbonate are added and let it react for another 90 minutes. The pH value now stands at 5.82. Pre-greasing is started with 2% of a synthetic grease (®Coripol DX 902 (Stockhausen), which has been previously diluted with water in a ratio of 1: 4) and allowed to react for 15 minutes. Then retanning is applied: 2% of a partially neutralized polyacrylic acid (Baytigan AR, which has been diluted with water in a ratio of 1: 3) and 1.5% of an acidic polyether (®) are added. Levotan C). After 45 minutes, 6% of a light and synthetic solid tanning agent (Tanigan LD-N) is added and allowed to react for 15 minutes. The pH value now stands at 5.36. Then 0.5% of formic acid (85%, which has been diluted before with water in a • ratio of 1:10) and allowed to react for 15 minutes and then the bath is discharged; pH value 4.6. It is washed with 200% water of 60 ° C for 10 minutes and the bath is discharged. Then it is greased: 100% water (60 ° C), 6% synthetic fat and light solid (Coripol DX 902) mixed with 1% of a substitute product of hoof oil (Coripol ICA) they are allowed to react for 45 * minutes The pH value rises to 4.62. Then 1.5% of an acrylate gluer (®Euderm Grund 25A, which has been diluted before with water in a ratio of 1: 4) is added and acidified after 30 minutes with 0.5% formic acid (at 85%, which has been diluted before with water in a ratio of 1:10). After 20 minutes a pH value of 4 is adjusted. It is then washed with water of 20 ° C for 5 minutes and can then remove the leathers. After drying under vacuum for 3 minutes at 70 ° C, the leathers are dried. It is clicked, spanked, ventilated and then spanked again. A part of the leathers is then provided with a coating of ®Levacast (2-component reaction coating in the leather inversion process by means of a prepolymer of - # - «. isocyanate and a partially blocked oligomer hardener in a solution of methyl ethyl ketone). b) According to the invention The example is repeated. In this case, instead of the partially neutralized polyacrylic acid (Baytigan AR), 3.5% of the esterurethane to be used according to the invention is used. The split leather, which has been obtained according to the state of the art and which has been tested after 24 hours, was clearly harder than that according to the invention. The same leathers subsequently coated with Levacast showed after 24 hours in that according to the invention a better appearance of the flower than in that according to the state of the art. The appearance of the flower is called behavior, when the leather is folded: a good aspect of the flower stands out for the fact that only small folds appear in the fold of the leather. The leather, which has been obtained according to the state of the art, is more hydrophilic than that according to the invention. In the leather according to the state of the art a drop of water is immediately immersed in the substrate; A leather obtained according to the invention keeps the water drop for a longer time. Surprisingly it has this effect, however, no negative influence on the adhesion of the subsequent coating. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the one that is clear from the present description of the invention .- Having described the invention ca or above, claim camo ownership the content in the following fr * ..axs & awasataaax, ^

Claims (3)

«CLAIMS

1. - A process for retanning chrome-tanned leather, characterized in that it comprises applying to the leather a reaction product of: a) at least one glyceric mopaeter of a carboxarboxylic acid saturated with 12 to 18 carbon atoms, b) at least one diisaciapate selected from the group consisting of toluepdi isociapata, hexamethylene diisacylpata and isafaropa diisocyanate, and c) dimethylalpropylactic acid, wherein: i) the components (a), (b) and (c) are selected in such a way that the ratio molar of the isocyanate groups of component (b) in relation to the sum of the hydroxyl groups of components (a) plus (c) is from about 0.5 to about 1.G5, and _ ^ ~ ii) the molar ratio of the compound (c) compound (a) is from about 0.7 to about 1.5 and in dope, iii) the carbaxyl groups that originate from compound (c) are neutralized at least partially.

2. - The process of compliance with claim 1, characterized park the molar ratio of (i) is 0.8 to 1.0.

3. The process of compliance with claim 1, characterized park the molar ratio of (ii) is 0.8 to 1.2. k. - The use of the reaction products of: a) at ore a glyceric mapaester of an acid * saturated carbonaceous map with 12 to 18 carbons, b) at least one diisocyanate of the isacianate tallowe series, hexamethylepdiisaciapata and IPDI (isafaropa isocyanate), and c) dimethylolipathic acid, the amounts of which are chosen. components (a) to (c) in such a way that the molar ratio of the isocyanate groups of (b) to the sum of the hydroxyl groups of (a) and (c) amounts to 0.5 to 1.05 and the molar ratio from e) / (a) to 0.7 to 1.5 and where the carbaxyl groups from (c) are partially neutralized for the retanning of chrome tanned leather. In testimopia of which I sign the present in this Mexico City, D.F., on August 17, 199 ¿+.