ES2296627T3 - AGENT FOR LEATHER PREPARATION. - Google Patents

Abstract

A liquid composition, stable during storage and in emulsion, usable for wet sizing of leather and skin, which comprises as components a) a lubricant based on unsaturated natural or synthetic fats, oils or waxes, whose fats, oils or waxes natural or synthetic unsaturated have undergone an oxidative treatment before any other chemical reaction, b) a retanning agent, and c) pH regulating substances, as well as optionally other additional components, whose composition allows to perform in a single stage and bath the neutralize, retanch and lubricate operations.

Description

Agent for leather sizing.

The invention relates to a liquid agent that It has a long storage life, usable for sizing wet leather, and allowing simultaneous retanning, lubrication or other leather finishing in a single bath.

The wet sizing of leather comprises several operations. During neutralization, the pH value is regulated as required in subsequent processes, using salts organic or inorganic with alkaline reaction. The lubrication is the responsible for the softness of the leather, by incorporating lubricating substances that reduce friction between the elements Structural leather. In retanning, they finally adjust, among other factors, character, body and resistance to cracking the leather, using vegetable tanning agents, mineral or synthetic These operations are performed successively and partially in separate bathrooms. The present degree of development is described, for example, in Magerkurt, B .: "Aktuelle Gesichtspunkte und Stand der Technik im Bereich der Naßzurichtung und Zurichtung ", in Das Leder H.1, 1996, p. 7-14, and in "Bibliothek des Leders", Vol. 3, Faber, K. "Gerbmittel, Gerbung und Nachgerbung" (Umschau Verlag, Frankfurt / Main, 1984), and Vol. 4 Hollstein, M., "Entfetten, Fetten und Hydrophobieren bei der Lederherstellung" (Umschau Verlag, Frankfurt / Main, 1987).

To achieve an efficient procedure, they have made numerous attempts to combine in a single operation Some or all sub-processes. For example, Wachsmann, H. in: Das Leder, H.6, 1981, p. 109-112, describes a compact procedure in the which all operations are performed in a single bathroom, although in succession, using several different products. At the same time, Wachsmann points out the difficulties that arise, specifically The compatibility of the products used. In effect, the main problem is that the products needed to These sub-processes are not miscible with each other, being unstable in the production of usable emulsions, at split into its components, or even causing its mutual precipitation. Even using conventional emulsifiers the production of stable liquid formulations that give rise to stable emulsions, it has not yet been possible.

DE-OS Patent 19653549 preferably provides a solid agent for said compact procedure For example the necessary components are subject to spray drying in order to obtain a presentation Keep it stable during its storage life. A reference Explicit to the instability of liquid formulations is Contains in the document. Even when a dilution of at least eight times, in the way that these formulations are regularly used, stable emulsions are not obtained in the that the micelles include both the tanning agent and the lubricating molecules This can only be achieved temporarily. using ultrasound. However, the ultrasonic treatment of the emulsions a moment before using them is complex and It is generally not available to users of these products.

However, solid products imply Several disadvantages. Its manufacture requires a great contribution of energy that does not seem to be justified as a result of only dissolved liquid products can be used, i.e. All solids should dissolve before or during treatment. The handling and measurement are somewhat complex. In general, the Measuring devices for powder products are not available in the tanning factories, so that large quantities that are required must be measured manually. On the other hand. the Tanning factories are equipped with measurement units for liquids Salts, such as sodium sulfate, are used as carrier substances that pollute the environment but do not have positive effects in terms of use. On the contrary, even They can adversely affect the leather. Thus, the important parameter of quality that refers to leachable organic compounds (DIN 53307) may be exceeded as a result of high salt concentrations, which in turn can lead to efflorescence of salt in the leather, or require additional processes of washing with greater water consumption.

Therefore, it was intended as an objective find an agent that presents both tanning properties and lubricants, as well as pH regulating characteristics, and that was present at room temperature in liquid form and with Long storage life. When diluted with water, it should form a stable emulsion in which micelles include both Tanning agent as lubricating molecules. Thus, the agent must allow a compact procedure for wet sizing, by example at least in the operations of neutralization, retanning and single stage lubrication. For this reason, the agent must include lubricants, retanning agents, regulatory substances of pH, and optionally other additives as components.

Surprisingly, it has now been discovered that when grease, oil or wax based lubricants are used natural or synthetic unsaturated, subjected to a treatment oxidative before any other chemical reaction, are obtained stable liquid mixtures with tanning agents and substances pH regulators, which form emulsions completely stable after being diluted with water.

The liquid agent of the invention that is stable during storage and emulsion, usable for sizing in wet leather and leather and that allows the operations of neutralize, retanch and lubricate in a single bath and stage, includes as components: lubricants based on greases, oils or waxes natural or synthetic unsaturated, whose fats, oils or waxes natural or synthetic unsaturated have undergone a treatment oxidative before any other chemical reaction; agents of retanned pH regulating substances; and optionally, others components.

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Oxidative treatment of fat, oil or unsaturated wax used as starting material, should be performed so that the amount of iodine is reduced by at least 20 units,  preferably in about 30 to 40 units. Oxidation can be done by introducing atmospheric oxygen at temperatures between 70 and 120 ° C, or using suitable oxidizing agents, such as hydrogen peroxide.

After said oxidation process, perform an additional chemical reaction to obtain the lubricant in a well known way, for example by sulfation, sulfocloration, phosphation, ethoxylation, amidation or preparing corresponding sulphosuccinates, with the aim of making non-water-soluble greases, oils and waxes are emulsifiable in Water.

The bases for the lubricant component are all those natural or synthetic fats, oils and waxes that have enough unsaturated links to be susceptible to an oxidation process Among the large number of raw materials potential, examples of lubricating components of origin Natural are: fish oils, rapeseed oil, soybean oil, Lecithin and many others. The original lubricant components synthetic are for example polyunsaturated hydrocarbons with a chain length> C 12, unsaturated fatty alcohols with a chain length> C 12, unsaturated fatty acids with a chain length> C 12, or fatty acid esters unsaturated

As retanning agents are possible well known vegetable and synthetic tanning agents. The agents Vegetable tanning are extracts of plants or parts of plants (for example, bark, fruits, wood or roots) containing pyrogallol or catechol and / or its derivatives. Tanning agents synthetic are for example condensation products of formaldehydes with aromatic compounds that may also be present in sulfonated form. Such condensation products can be further processed in the form of sulfonic acid free, or its lithium, sodium, potassium or ammonium salts. In addition, the formaldehyde condensation products with nitric bases, such as urea, melamine, thiourea and dicyandiamide are possible as components of tanning agents. Tanning agents Synthetics also include polymeric tanning agents that are water-soluble polymers based on acrylate, polyurethane or polybutadiene. Tanning agents are also possible aldehydes, such as glutaric aldehyde, acetaldehyde and propionaldehyde, and other aliphatic aldehydes, as well as acids aldehyde, such as glyoxylic acid. A detailed illustration and description of possible vegetable and synthetic tanning agents is offered at Kurt Faber, "Gerbmittel, Gerbung und Nachgerbung" in the series "Bibliothek des Leders", Vol. 3 (Umschau Verlag, Frankfurt, 1985).

Examples of pH regulating substances include: alkaline earth oxides and earth hydroxides alkaline, ammonium compounds, as well as other inorganic salts and organic that show a basic reaction.

It is understood that the optional components are materials that do not necessarily have to be present in the agent of the invention, although there may be some case of component that is necessary for the formulation. These include solvents, such as alcohols or hydrocarbons, preservatives, antioxidants, fillers such as urea or rock salt, regulators viscosity as mineral oils of different viscosities, etc.

Therefore, the agent of the invention includes the following components (in weight percent)

a) Lubricant

10-90% by weight, preferably 20-80%

b) Agent of tanning

10-90% by weight, preferably 20-80%

c) Regulatory substances of pH

1-30% in weight,

and optionally

d) Other additives

0-30% in weight.

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The components are mixed and homogenized by stirring in a stirring reactor at temperatures between 20 and 90 ° C, preferably at temperatures between 30 and 60 ° C. They do not exist special requirements regarding the agitator. The products obtained are clear, liquid and completely stable during storage. Storage stability is guaranteed. both at low temperatures, for example below -30 ° C, and high temperatures, for example up to 60 ° C.

With the use of the agents of the invention, the use of Formulations for wet leather sizing. After washing of leather, so as to remove shaved and possible materials dirt, water is added to the leather in an amount of 20-200%, preferably 50-150% (in relationship with the weight of the shaves) and 5-30%, preferably 10-25% of the agent according to the invention. In general, the agent of the invention is pre-emulsified using a quantity of water four to eight times, which forms an opaque emulsion completely stable, whose micelles include tanning agent and lubricating molecules These emulsions are stable for long periods of time, without separation between the components present. However, a direct calibration without preparation is possible prior to an emulsion. Processing temperatures are between 20 to 60 ° C, preferably from 30 to 50 ° C.

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After a period of treatment of 1-4 hours, preferably 2-3 hours, a pH value of 3.5 to 3.8 is adjusted using acids organic, and leathers are prepared by an operation conventional. The dyeing of the leathers can be done well by adding dye in the previous process or as part of a subsequent operation

By employing the agent of the invention, virtually any type of leather can be produced, such as leather for upholstery, car clothing, shoe and clothing, as well as technical leathers. The composition of the agent of the invention It can be modified according to the demands of the leather to be produced. Thus, for example, hard and rigid leather types require a higher percentage of tanning agent and a lower percentage of agent lubricant. Correspondingly, the amount of lubricant predominates in soft leathers. Naturally, the type of components added the product also has an influence on the character of the leather resulting. Such modifications of the composition do not affect adversely to the stability properties of the agent of the invention and its emulsions.

The use of the liquid agent according to the invention It offers a range of advantages for the user. It only takes more than a single product for wet sizing, which can be stored in a tank and measured automatically, which is advantageous both logistically and economically. Processing time, when significantly reduced, represents an advantage in terms of production, saving investment costs. As a result of such simultaneous processing, they are saved significant amounts of water and waste, both in terms Economic as ecological.

The following describes in more detail the production and use of the agent of the invention, with reference to the examples.

Production example one

Component A ( lubricant ): rapeseed oil with an amount of iodine of 110 is oxidized at 90 ° C with atmospheric oxygen to an amount of iodine of 80. Upon completion of oxidation, it is ethoxylated using 10 moles of ethylene oxide and subsequently sulfonated to obtain an organically bound SO3 content of about 2.0%.

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

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

In a stirred reactor, 58 parts are added of component A and 30 parts of component B to 10 parts of sodium formate and 2 parts triethanolamine, and stir until homogeneity at 60 ° C. Water content is adjusted to 40% by decarbonized water A golden yellow oily product is formed which is completely stable when stored in a range of temperature from -20 ° C to + 50 ° C, and that forms emulsions completely stable and fine dispersion when diluted in water.

Production example 2

Component A ( lubricant ): Fish oil with an iodine amount of 130 is homogeneously mixed with sebaceous oil fatty acid methyl ester that has an amount of iodine of 155 in a 1: 1 ratio, and is subjected to oxidation with atmospheric oxygen at 110 ° C. The reaction is maintained until an amount of iodine of 100 is reached. 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 dihydroxydiphenylsulfone with a dry content of 45% and a sodium polyacrylate with an average molar mass of 25000 g / mol and a dry content of 35% are mixed until homogeneous at room temperature.

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

Component D: urea, chloroacetamide.

In a stirred reactor, mix until homogeneity at 50 ° C 35 parts of component A, 50 parts of component B, 5 parts of ammonium acetate, 0.5 parts of triethanolamine, 9 parts of urea and 0.5 parts of chloroacetamide, and fit up to 60% water content with water decarbonized The pH value is checked and eventually Adjust to 7.8-8.2 with triethanolamine. It forms a dark brown translucent product that is stable in storage. An opaque milky emulsion forms when diluted in water in a 1:10 ratio.

Example of use 3

They underwent conventional tanning with chrome pickled skins of Australian sheep. The samples (wet blue) obtained were shaved to 0.6 mm and were pressed with the Compact formulation that follows, using the agent of the invention described in Example 1, whereby the neutralization, tanning and lubrication in a single bath. The agent of Example 1 was emulsified at a temperature of 40 ° C using the fivefold amount of water. The percentages refer to shaving weight

one

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The leathers were prepared by an operation conventional, and were smooth, resistant to cracking and They had a uniform dyeing.

Example of use 4

Samples (wet blue) of cow leather from shaved raw German-skinned skins at a thickness 1.2 mm, were processed for upholstery leather according to the formulation that follows, with the agent of Example 2. The agent of the Example 2 was used directly, without prior emulsion. The percentages refer to shaved weight.

3

The leathers were prepared by an operation conventional. The pressed leathers stood out for their softness with Simultaneous cracking resistance, fine and uniform texture. He dyeing was uniform both on the surface and in section.

Claims (5)

1. A liquid composition, stable during storage and emulsion, usable for wet sizing of leather and skin, which includes as components

to)

a lubricant based on natural or synthetic fats, oils or waxes unsaturated, whose natural or synthetic fats, oils or waxes unsaturated have undergone an oxidative treatment before any other chemical reaction,

b)

a retanning agent, and

C)

pH regulating substances,

as well as optionally others additional components, whose composition allows to realize in a single stage and bath the operations of neutralizing, retanning and lubricate. 2. The composition for wet leather and leather sizing according to claim 1, characterized in that during the oxidative treatment the amount of iodine is reduced by at least 20 units and because the oxidative treatment is carried out using atmospheric oxygen or other oxidizing agents adequate. 3. The composition for wet sizing of leather and skin according to claims 1 and 2, characterized in that said additional chemical reaction of the fats, oils or waxes treated by oxidation is sulphation, phosphating, ethoxylation, amidation and / or a reaction to form sulfosuccinates, or a combination of these processes. 4. The composition for wet sizing of leather and leather according to claims 1 to 3, comprising:

to)

10-90% by weight of a lubricant,

b)

10-90% by weight of a retanning agent,

C)

1-10% by weight of a pH regulating substance, and

d)

0-30% by weight of others additives

5. Use of the composition according to claims 1 to 4 in the form of an aqueous solution or dispersion for the sizing of leather or skin in a single bath and stage of treatment.