CS261326B1 - A method for treating leather and flexible fibrous material - Google Patents

Abstract

The solution concerns the issue of leather surface treatment, in which a special preparation is used in combination with polymer binders and color pigments, influencing the formation of the treatment film. The aim is to improve the properties of the surface treatment, in particular by using the said preparation, applied under the conditions according to the solution, to achieve the desired degree of leather coloring at the optimal thickness of the treatment film, which creates a basic prerequisite for high-quality and aesthetic surface treatments.

Description

The invention relates to the issue of leather surface treatment, in which a special preparation is used in combination with polymer binders and color pigments, influencing the formation of the treatment film. The purpose of the invention is to improve the properties of the surface treatment, in particular by using the said preparation, applied under the conditions according to the invention, to achieve the desired degree of leather coloring at the optimal thickness of the treatment film, which creates a basic prerequisite for high quality and appearance parameters of the surface treatment.

The surface treatment of leather, which forms the final link in the complex technological process of converting hides into leather, is one of the main criteria determining their quality and marketability.

It is therefore clear that considerable care and attention has been and will always be paid to it, which is reflected in the use of a very wide and relatively rapidly changing range of finishing products. Their purposeful application allows the properties of the leather surface to be changed to a wide extent, thus achieving the criteria required for individual types of leather according to their use.

The repair gives the leather the desired color shade, uniformity or, conversely, variety of coloring, affects the fineness of the face pattern, high gloss or matt, etc. In terms of physical properties, the leather treatment must be sufficiently elastic so that it does not crack when the leather is sharply bent or when it is repeatedly bent, e.g. when walking, or at elevated or low temperatures. The repair must have sufficient adhesion so that it does not peel off during the production or wearing of leather shoes. The repair must have sufficient strength and resistance to water so that it does not rub or fray, whether dry or wet. Furthermore, the treatment must be sufficiently heat-resistant and light-resistant to withstand ironing at higher temperatures and weather conditions and sunlight. The requirements for the properties of the leather surface treatment indicate that the range of tannery preparations for surface treatment is extremely wide. In principle, however, they can be divided into four basic groups according to their purpose and use. They are:

1. Paints for leather finishing

2. Basic film-forming binders

3. Binders for final protective layers

4. Special auxiliary preparations

As mentioned, the basic criterion for evaluating the quality of a surface treatment is its physical properties, which determine its useful properties. These properties can be ensured, apart from the appropriate selection of products from individual basic groups, by the actual surface treatment technique, in particular by the optimal thickness of the applied film of the treatment, which has a direct impact on its bending resistance, adhesion and thus the behavior when wearing shoes. The disadvantage of the formulas and techniques used so far is the fact that when performing the surface treatment itself, the required amount of coating is governed by the degree of covering the leather surface, so that the optimal film thickness is often exceeded. This results in a deterioration of the physical properties of the treatment. Another negative accompanying phenomenon is higher labor intensity, consumption of treatment products, higher need for electrical energy to drive machines and thermal energy for drying a higher number of applications of treatment solutions. Therefore, there are efforts to regulate and increase the coverage of finishes. This can be achieved in two ways. By changes in the quality and quantity of pigments used or by reducing the absorbency of the leather surface. Since the leather surface is considerably inhomogeneous and individual leathers differ from each other, or the leather surface may be damaged or processed, e.g. abraded, it is more appropriate to reduce the absorbency and penetration ability of finishing solutions. For this purpose, special leveling preparations have been used so far, most often produced on the basis of paraffin, which, however, when the required reduction in absorbency is achieved, often worsen the adhesion of the surface treatment to the face of the leather, or negatively affect the physical properties of the treatment. These deteriorated properties of the treatment are related to the fact that the increased content of pigments or leveling substances disrupts the integrity of the film of the polymer binder used, especially when reaching the so-called critical volume concentration, especially because these substances differ significantly in their properties from the properties of polymer binders. These shortcomings are avoided by the surface treatment process according to the invention, where, to increase the coverage, a special leveling agent is added to the polymer binder and pigments, consisting of a mixture of an aqueous dispersion of a wax component, a binding component of the nature of an acrylate copolymer, a protective colloid and an oil component, manufactured under the name Egalton and protected by AO 240 027. Due to the content of substances of a wax nature, this Egalton preparation reduces the penetration ability of the finish, due to the presence of an acrylic polymer it ensures the maintenance of the quality of the formed polymer film even with an overall increased volume concentration of pigments and leveling waxes. The addition of a leveling agent to the finishing finish therefore increases the compactibility of the film even with a significantly increased coverage of the system. This compactibility of the film is given by the fact that, with a constant amount of polymer binder, the EGALTON leveling agent ensures such a distribution of the pigment in the finishing film that corresponds to a state below the critical volume concentration, even if this concentration would be exceeded without the use of EGATON. While in commonly used finishing solutions it is not possible to exceed the limit of 15 to 20% of the pigment concentration by volume without deteriorating the quality of the finishing, when using DGALTON this limit is shifted to 20 to 25%, with a significantly increased evenness of the applied layer. This effect is achieved if the leveling agent EGALTON is dosed in an amount of 20 to 120 g/1 of finishing solution, preferably 60 to 100 g/1, with a dry content of polymer binders in the range of 10 to 18%. The result of performing the surface finishing according to the invention is then the possibility of reducing the number of individual layers of finishing required to cover the leather surface by 10 to 30%, which will result in significant savings in chemicals, heat and electricity and increased work productivity. Among the accompanying advantages of this method of surface treatment according to the invention is the fact that the formed surface treatment film exhibits reduced stickiness at normal and elevated temperatures due to the presence of a wax component in the leveling agent, which allows intermediate ironing of the surface treatment at temperatures of 70 to 90 °C and thus further improves the compatibility and resulting physical properties of the surface treatment film without the leathers sticking together when they are placed on top of each other after ironing. The higher compactness of the treatment film caused by the addition of EGATON also allows the amount of water usually added to the treatment formulas to be reduced by up to 50%, which speeds up drying between individual layers and again positively affects the physical properties and reduces the stickiness of the treatment.

The surface treatment according to the invention can be practically carried out according to any of the following examples:

Saturday Spray 120 220 100 60 350 300 430 420

Example 1

Composition of the treatment solution for surface treatment of a beef box with a corrected face, composition in parts by weight:

Casein opaque paint, tinted EGALTON, leveling agent Mixture of polymer binders Water

Example 2

Using EGATON for surface treatment of full grain leather in white:

Saturday Spray A) Casein white opaque paint 130 230 Casein opaque paint ochre 1 - EGALTON 90 70 Polymer binder mixture 330 300 Water 449 400 B) Treatment with reduced water quantity Casein opaque white paint 175 280 Casein opaque paint ochre 1 - EGALTON 120 100 Polymer binder mixture 440 300 Water 264 240

Example 3

Use for surface treatment of colored full grain leathers:

Coating + Spraying

Casein covering colors tinted EGALTON

Polymer binder mixture

Water-based nitro-emulsion varnish

Water

220

320

350

Repair solutions are applied using commonly used techniques, i.e. by painting, spraying or pouring. In the case of pouring, the solutions are thickened to the required viscosity by adding thickening agents.

Claims (3)

object of the invention Method for treating leather and flexible fiber materials of a fibrous character, characterized in that 20 to 120 g / l of a special leveling agent based on an aqueous dispersion of a wax component, a binder of the character, are added to the mixture of pigments and polymer binders. an acrylate terpolymer and a protective colloid, for example manufactured under the trade name EGALTON, at a dry weight of polymeric binders of 10 to 18%. 2. The process of item 1, wherein to increase the opacity, the pigment pigment volume concentration is increased from the usual 12 to 20% up to 25%, i.e., depending on the dry matter and specific gravity of the pigments, in an amount of 220 to 300 g / l of treatment solution. 3. The method according to items 1 and 2, wherein, in order to increase the compactness and opacity of the film, the addition of water for dilution is reduced by 10 to 60% over commonly used formulations.