EP1299565A1

EP1299565A1 - Leather finishing agent

Info

Publication number: EP1299565A1
Application number: EP00940380A
Authority: EP
Inventors: Heinrich Francke; Jörg-Detlev STUMM
Original assignee: Zschimmer and Schwarz GmbH and Co KG
Current assignee: Zschimmer and Schwarz GmbH and Co KG
Priority date: 2000-06-16
Filing date: 2000-06-16
Publication date: 2003-04-09
Anticipated expiration: 2020-06-16
Also published as: WO2001096613A1; EP1299565B1; DE50014822D1; ES2296627T3

Abstract

The invention relates to liquid agents for the wet reconditioning of leather, enabling simultaneous one dip retanning, oiling and other forms of finishing. The inventive agents are obtained by using unsaturated fat, oil, waxes of a natural or synthetic origin as starting materials in the production of the oiling agent, and by making said starting materials undergo oxidative treatment before any further chemical treatment.

Description

Leather finishing agents

The invention relates to a liquid and storage-stable agent for the wet finishing of leather, which enables a one-bath, simultaneous retanning, greasing and other finishing of 5 leather.

The wet finishing of leather involves several operations. During neutralization, the use of alkaline, inorganic or organic salts regulates the pH value required for the further processes. The greasing is responsible for the softness of the leather due to the introduction of greasy substances that reduce the friction between the structural elements of the leather. Finally, retanning with vegetable, mineral or synthetic tanning agents Leather character, fullness and grain resistance set. These operations are carried out one after the other in partially separate baths. The current state of development is e.g. 5 by Magerkurt, B .: "Current aspects and state of the art in the field of wet dressing and dressing", in: Das Leder H.1, 1996, pp. 7-14 and in "Bibliothek des Leders", volume 3, Faber, K., "Tanning agents, tanning and retanning" (Umschau Verlag, Frankfurt am Main 1984) and Volume 4 Hollstein, M., "Degreasing, greasing and waterproofing in leather production" (Umschau Verlag, Frankfurt am Main 1987). 0

In order to achieve a rational way of working, there has been no lack of attempts to combine individual or all sub-processes in one work step. For example, Wachsmann, H. in: Das Leder, H.6, 1981, pp. 109 - 112, a compact way of working in which all work steps in a bathroom are carried out in succession with a multitude of different products. Wachsmann also points out the difficulties that arise, namely the compatibility of the products used. In fact, the main problem is that the products required for these sub-processes are not miscible with one another and are not stable in the production of application-relevant emulsions and separate into their components or even cause mutual precipitation. The use of conventional emulsifiers has not hitherto been able to produce stable, liquid preparations which also give stable emulsions.

OS DE 196 53 549 therefore preferably provides a solid agent for such a compact product, ie the necessary components have to be spray dried, for example, in order to achieve a shape which is stable in storage. On the instability more fluid Preparations are expressly indicated. Even in the preparation of an at least eight-fold dilution, such as these preparations are usually used, no stable emulsions are formed in which the micelles contain both tannin and lipid molecules. This can only be achieved temporarily by using ultrasound. However, ultrasound treatment of the emulsions prepared shortly before use is complex and is generally not available to the users of these products.

Solid products have some serious disadvantages. The production requires a large amount of energy, which is due to the fact that only dissolved, liquid products can be used, i.e. that all solids must be dissolved before or during treatment does not appear to be justified. Handling and dosing require more effort. Dosing devices for powder products are generally not available in the leather factories, so that the required large quantities would have to be dosed by hand. The leather factories, on the other hand, are equipped with dosing systems for liquids. Salts such as e.g. Sodium sulfate, used that pollute the environment, but have no positive application effects. On the contrary, negative influences can even be exerted on the leather. It is therefore possible that the important quality parameter 20 of the washable inorganic compounds (DIN 53307) is exceeded due to the high salt concentration, which in turn can lead to salt build-up on the leather or make additional, water-consuming washing processes necessary.

It was therefore the task of finding an agent which has both tanning and greasing properties and which regulates the pH and which is in liquid and storage-stable form at room temperature. Dilution with water should result in a stable emulsion in which the micelles contain both tannin and fatliquor molecules. The agent must therefore a compact mode of operation in the wet dressing, ie at least the operations of neutralizing, retanning and greases ₃ o tung allow in one step. The agent must therefore contain fatliquoring agents, retanning agents and pH-regulating substances as components as well as possibly other additives.

Surprisingly, it has now been found that when using fatliquor on the

₃ 5 Basis of natural or synthetic unsaturated fats, oils or waxes, which were subjected to an oxidative treatment before further chemical conversion, stable le, liquid mixtures with tannins and pH-regulating substances are obtained, which form completely stable emulsions when further diluted with water.

The liquid, storage- and emulsion-stable agent according to the invention for wet dressing of leather and fur, which enables the neutralization, retanning and greasing operations to be carried out in one treatment step, contains, as components, fatliquoring agents, retanning agents and pH-regulating substances and optionally further components and is characterized in that unsaturated fats, oils or waxes of natural or synthetic origin are used as the starting material for the production of the fatliquoring agent and are subjected to an oxidative treatment before a further chemical reaction.

The oxidative treatment of the unsaturated fat, oil and wax starting materials according to the invention must be carried out in such a way that the iodine number is reduced by at least 5 units, but preferably by 30-40 units. The oxidation can be carried out by introducing atmospheric oxygen at temperatures between 70 and 120 ° C, or by suitable oxidizing agents, e.g. Hydrogen peroxide.

Following the oxidation process, the further chemical conversion to the degreasing agent takes place in a known manner, e.g. by sulfation, sulfochlorination, phosphating, ethoxylation, amidation or preparation of the corresponding sulfosuccinates, with the aim of making the water-insoluble fats, oils and waxes water-emulsifiable.

The basis for the fatliquor component are all natural or synthetic fats, 5 oils and waxes, which have sufficient unsaturated bonds, so that they are accessible to an oxidation process. From the large number of possible starting materials, the following are examples of fat components of natural origin: fish oils, rapeseed oil, soybean oil, lecithin and many others. Fat components of synthetic origin are e.g. polyunsaturated hydrocarbons with a chain length> C12, unsaturated fatty alcohols with a chain length> C12, unsaturated fatty acids with a chain length> C12 or esters of unsaturated fatty acids.

The known vegetable and synthetic tanning agents come in as retanning agents

Consideration. Vegetable tannins are extracts from plants or 5 parts of plants (e.g. bark, fruit, wood, roots) that contain pyrogallol or pyrocatechol or their derivatives. The synthetic tanning agents are, for example Condensation products of formaldehyde with aromatic compounds, which may also be present in their sulfonated form. The condensation products can be processed further in the form of the free sulfonic acid or its lithium, sodium, potassium or ammonium salt. Condensation products of formaldehyde with nitrogen bases, such as urea, melamine, thiourea and dicyandiamide, are also suitable as tannin components. The synthetic tanning agents also include the polymer tanning agents, which are water-soluble polymers based on acrylate, polyurethane or polybutadiene. Also suitable are aldehydic tannins such as glutaric, acetaldehyde and propionaldehyde or other aliphatic aldehydes, but also aldehyde carboxylic acids such as glyoxalic acid. Kurt Faber "Tanning agents, tanning and retanning" from the series "Library of leather", volume 3 (Umschau Verlag, Frankfurt 1985) provides a detailed description and description of the vegetable and synthetic tanning agents that are considered.

The pH-regulating substances include, for example: alkaline earth oxides, alkali and alkaline earth hydroxides, ammonium compounds and other basic inorganic and organic salts.

Substances are to be understood as optional further components which do not necessarily have to be constituents of the agent according to the invention, but in individual cases can be constituents necessary for the formulation. These include, for example, solvents such as alcohols or hydrocarbons, preservatives, antioxidants, adjusting agents such as urea or common salt, viscosity regulators such as mineral oils of different viscosities etc.

The agent according to the invention accordingly contains the following constituents (in% by weight): a) fatliquor 10-90%, preferably 20-80% b) tannin 10-90%, preferably 20-80% c) pH-regulating substances 1 - 30% 5 and if necessary d) further additives 0 - 30%

The components are removed by stirring e.g. mixed and homogenized in a stirred reactor at temperatures between 20 and 90 ° C., preferably at temperatures between 30 and 60 ° C. There are no special requirements for the design of the agitators. Completely stable, clear, liquid products are created. The storage stability is both at low temperatures, e.g. down to -30 ° C, as well as at high temperatures, e.g. up to 60 ° C.

5 By using the agent according to the invention, the recipes for the wet finishing of the leather are considerably simplified. After washing the leather in order to remove shavings and possibly dirt, the leather is given an amount of water of 20-200%, preferably 50 to 150% (based on the shaved weight) and 5-30%, preferably 10-25%, of the agent according to the invention added. As a rule, the agent according to the invention is pre-emulsified with four to eight times the amount of water. The result is a completely stable, opaque emulsion, the micelles of which contain both tannin and fat molecules. These emulsions are stable for a long time without being separated into the components. However, direct metering is also possible without the prior preparation of an emulsion. The process temperatures are 20 - 60 5 ° C, preferably 30 - 50 ° C.

After a treatment time of 1 to 4 hours, preferably 2 to 3 hours, a pH of 3.5 to 3.8 is set with organic acids and the leathers are finished in the normal manner. The leather can be dyed either by adding dye during the above-mentioned process or in a subsequent additional operation.

Practically all types of leather, such as e.g. Furniture leather,

Car upholstery leather, leather for shoe manufacture, clothing leather but also technical leather. Depending on the requirements of the leather to be produced, the

The composition of the agent according to the invention can be varied. For example, for firmer, more permanent types of leather require a higher tannin and a lower fat content. For soft types of leather, the proportion of fat and grease dominates. The type of components used in the product naturally also influences the leather character of the resulting leather. Such variations in the composition have no negative influence on the stability properties of the agents according to the invention and their emulsions.

The use of the liquid agent according to the invention offers the user a multitude of advantages. Only one product is required for wet dressing, which o can be stored in the tank and dosed automatically. This offers both logistical and cost advantages. The very short process time represents a gain in capacity and saves any investment costs. The simultaneous process control saves significant amounts of water and wastewater, which represents both a cost and an ecological advantage. 5

The preparation and use of the agent according to the invention are explained in more detail below using examples.

Production example 1: 0

Component A (fatliquor): Turnip oil with an iodine number of 110 is oxidized at 90 ° C with atmospheric oxygen up to an iodine number of 80. After completion of the oxidation, ethoxylation with 10 moles of ethylene oxide followed by sulfonation to an organically bound SO ₃ content of approximately 2.0%. 5

Component B (tanning agent): synthetic tanning agent based on a condensation product of phenolsulfonic acid, phenol, urea and formaldehyde with a dry substance of 50%.

o Component C (pH-regulating agent): sodium formate, monoethanolamine

At 60 ° C., 58 parts of component A, 30 parts of component B are mixed with 10 parts of sodium formate and 2 parts of triethanolamine in a stirred reactor and stirred until homogeneous. A water content of 40% 5 is set by adding decarbonated water. A golden yellow oily product is formed, which is stored in a temperature range from -20 to +50 ° C is completely stable in storage and results in completely stable finely dispersed emulsions when diluted with water.

Production example 2:

Component A (fatliquor): Fish oil with an iodine number of 130 is mixed in a 1: 1 ratio with tall oil fatty acid methyl ester with an iodine number of 155 and subjected to oxidation with atmospheric oxygen at 110 ° C. The reaction is carried out until the mixture reaches an iodine number of 100. The reaction product is then subjected to sulfonation and neutralized with triethanolamine. The product has an organically bound SO ₃ content of 4.5%.

Component B (tanning agent): A condensation product of formaldehyde and dihydroxydiphenyl sulfone with a dry substance of 45% and a Na polyacrylate with an average molecular weight of 25000 g / mol and a dry substance of 35% are mixed homogeneously at room temperature.

Component C: (pH-regulating agent): ammonium acetate, triethanolamine

Component D: urea, chloroacetamide

35 parts of component A, 50 parts of component B, 5 parts of ammonium acetate, 0.5 part of triethanolamine, 9 parts of urea and 0.5 part of chloroacetamide are mixed homogeneously at 50 ° C. in a stirred reactor and brought to a water content of 60 with decarbonated water % set. The pH is checked and, if necessary, adjusted to 7.8 to 8.2 with triethanolamine. The result is a dark brown, clear and storage-stable product. When diluted with water in a ratio of 1:10, a milky opaque, stable emulsion is formed. Example of use 3:

Australian sheep pimples have been subjected to common chrome tanning. The "wet blue" thus obtained was folded to 0.6 mm and, according to the following compact formulation, in which neutralization, tanning and oiling take place simultaneously in a bath, using the agent according to the invention from Example 1. The agent from Example 1 was prepared before Application emulsified with five times the amount of water at a temperature of 40 ° C. The percentages relate to the fold weight.

Operation Medium Amount Temp. Duration pH

Wash water 200% 30 ° C 20 min 3.8

Entflotten

Neutralization / water 150%

Retanning / agent from Example 1 20% 40 ° C 90 min 5.9

Lubrication 1: 5 pre-emulsified with water

Coloring of anionic dye 3% 90 min

Acidify formic acid 85% 1, 5% 60 min 3.8

Wash water 200% 30 ° C 20 min

The leathers were finished in the normal way and were soft, scar-resistant and had a level color. Example of use 4:

Beef "wet blue" from raw material from southern Germany with a fold thickness of 1.2 mm was worked into furniture leather according to the following recipe using the agent from Example 2. The agent from Example 2 was used directly without prior emulsification. The percentages relate to that shaved weight.

Operation Medium Amount Temp. Duration pH

Wash water 200% 30 ° C 20 min 3.9

Entflotten

Neutralization / water 100%

Retanning / agent from Example 2 19% 40 ° C 90 min 6.2

greasing

Coloring of anionic dye 4% 90 min

Acidify formic acid 85% 2% 60 min 3.7

Wash water 200% 30 ° C 20 min

The leathers were completed in the normal way. The finished leather was characterized by high softness with simultaneous grain resistance and fine level mill grain. The coloring was uniform in area and cross section.

Claims

claims

1. Liquid, storage-stable and emulsion-stable agent for the wet finishing of leather and fur, which contains as components a) fatliquor and b) retanning agent and c) pH-regulating substances as well as optionally other components and the operations of neutralization, retanning and One-bath greasing made possible in one treatment step, characterized in that unsaturated fats, oils or waxes of natural or synthetic origin are used as starting materials for the production of the greasing agent and are subjected to an oxidative treatment before a further chemical reaction.

2. Means for wet finishing of leather or fur according to claim 1, characterized in that the iodine number is reduced by at least 20 units in the oxidative treatment and the oxidative treatment is carried out by atmospheric oxygen or other suitable oxidizing agents.

3. Means for wet dressing of leather or fur according to claim 1 and 2, characterized in that the further chemical conversion of the oxidatively treated fats, oils and waxes a sulfonation, phosphation, ethoxylation, amidation and / or a conversion to sulfosuccinates or a combination of these Represents procedure.

4. agent for wet dressing of leather or fur according to claims 1 to 3, containing a) 10 - 90 wt .-% of a fatliquor, b) 10 - 90 wt .-% of a retanning agent, c) 1 - 10 wt .-% a pH-regulating substance and d) 0-30% by weight of other additives

5. Use of the agent according to claims 1 to 4 in the form of an aqueous solution or dispersion for single-bathing leather or fur in one treatment step.