Leather Finishing Research Articles

Preparation and characterization of silicone oligomer modified polyurethane acrylates for leather finishing

Polyurethane acrylates (PUA) are commonly used as leather finishing agents because of their excellent film-forming, mechanical and abrasion resistance properties. In this study, silicone-modified polyether-based waterborne polyurethane acrylate (WPUA) was synthesized as an environmentally friendly leather finishing agent. The effects of different soft segments on the properties of WPUA were investigated by tensile strength, water absorption, thermogravimetry (TG), derivative thermogravimetry (DTG), and water contact angle tests. The results showed that the WPUA synthesized with PTMG 2000 as the soft segment had higher elongation at break, lower water absorption, and a larger water contact angle. The effect of different mass percentages of silicone on the properties ofpolytetramethylene oxide (WPUA) was investigated by scanning electron microscope (SEM), particle size, zeta potential, Fourier transform infrared spectroscopy (FT-IR), water contact angle, folding resistance, and mechanical properties. It was found that the hydrophobic, tensile, and folding resistance properties of the waterborne leather finishing agent were best when the silicone content was 5 wt%. What’s more, the synthesized silicone-modified polyether-type waterborne polyurethanes, with excellent comprehensive performance, have great potential for industrial application in leather finishing agents.

Novel Beeswax-neat’s-foot oil formulation and its impact on leather finishing

Leather finishing provides an esthetic look to the leather. Oil in combination with wax emulsion in the form of oleogel when applied to leather finishing produces a special class of leather known as crunch leather. Using an optimized ratio of Beeswax emulsion blended with Neat’s-foot oil in the form of oleogel for the making of crunch leather was investigated in this study. The chemical characterizations such as FTIR, dynamic light scattering, and particle size analysis, of the experimental emulsion were carried out. The experimental leathers undergo various tests such as contact angle measurements, optical microscopy imaging, color measurement, light fastness, fastness to dry and wet rub, tensile, tear strength, and elongation at break. The experimental leathers were showing better results than the control leathers. The present work focuses on the finishing of leather, and the interaction of oil and wax oleogel with leather which approaches a sustainable and eco-friendly process.

Co/SiO2 Catalyst for Methoxycarbonylation of Acetylene: On Catalytic Performance and Active Species.

Reppe carbonylation of acetylene is an atom-economic and non-petroleum approach to synthesize acrylic acid and acrylate esters, which are key intermediates in the textile, leather finishing, and polymer industries. In the present work, a noble metal-free Co@SiO2 catalyst was prepared and evaluated in the methoxycarbonylation reaction of acetylene. It was discovered that pretreatment of the catalyst by different reductants (i.e., C2H2, CO, H2, and syngas) greatly improved the catalytic activity, of which Co/SiO2-H2 demonstrated the best performance under conditions of 160 °C, 0.05 MPa C2H2, 4 MPa CO, and 1 h, affording a production rate of 4.38 gMA+MP gcat-1 h-1 for methyl acrylate (MA) and methyl propionate (MP) and 0.91 gDMS gcat-1 h-1 for dimethyl succinate (DMS), respectively. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and diffuse reflectance infrared Fourier transform spectra of CO adsorption (CO-DRIFTS) measurements revealed that an H2 reduction decreased the size of the Co nanoparticles and promoted the formation of hollow architectures, leading to an increase in the metal surface area and CO adsorption on the catalyst. The hot filtration experiment confirmed that Co2(CO)8 was generated in situ during the reaction or at the pre-activation stage, which served as the genuine active species. Our work provides a facile and convenient approach to the in situ synthetization of Co2(CO)8 for a Reppe carbonylation reaction.

A rapid room-temperature self-healing, antibacterial, photoluminescent waterborne polyurethane coating with excellent mechanical properties based on double dynamic cross-linked network used for leather finishing

Waterborne polyurethane that integrates fast room-temperature self-healable ability, high mechanical properties, antibacterial activity, and photoluminescence features is highly desirable but challenging. Herein, a novel waterborne polyurethane (ZIWPU) is synthesized with the double dynamic cross-linked networks of multiple hydrogen bonds formed by asymmetric polyurea structure and Zn2+-carboxylate coordination bonds. Profiting from the synergistic effects of double dynamic cross-linked networks, the optimized ZIWPU2 film exhibits excellent mechanical properties (tensile strength of 34.36 MPa and toughness of 107.21 MJ/m3) and rapid room-temperature self-healing ability (healing efficiency > 85 % within 10 h) with the assistant of trace alcohol, which is superior to those of the most of currently reported room-temperature self-healing waterborne polyurethane. In addition, owing to the existence of Zn2+, ZIWPU2 is simultaneously integrated with the outstanding antibacterial ability (antibacterial rate>96 %). Especially, the carbon dots (CDs) are introduced into ZIWPU2 to give it an excellent photoluminescence function that can be used for anti-counterfeiting and crack diagnosis. Finally, this versatile WPU material is successfully applied to leather finishing.

ASSESSMENT OF THE TECHNOLOGICAL CAPABILITIES OF MODERN CHEMICAL MATERIALS FOR LIQUID FINISHING OF LEATHER

Natural leather is a by-product of the meat industry, which turns into a valuable product that has high strength, stability, comfort, breathability and is considered one of the best products of the circular economy. In addition, less materials from non-renewable sources are used in leather production than in other industries, recycling of waste is practiced, which contributes to the protection of the environment and sustainable development of society. The choice of processing method, type of equipment and chemical materials is of great importance for the quality of leather and the ecological imperative of its manufacturing technology. At the same time, despite the progress of modern chemical technology, the leather industry constantly needs to find and introduce new, more effective means, which would not only be stable in their properties, available and compatible with the components of the «collagen-chemical material» system, but would also contribute the formation of this system in the direction of creating quality products while reducing the harmful load on the environment. The results of previous studies indicate the prospects of modified liquor materials and polymer compounds. Taking into account the above, the technological capabilities of modern commercial chemical materials - modified fats of various origins and acrylic polymer - were analyzed by using them in the liquid decoration of semi-finished Wet-blue half skin. Using the methods of organoleptic assessment, chemical analysis, physico-mechanical tests and microscopy, the advantages of these materials compared to those known during retanning-filling and liquoring have been established. The improvement of the indicators of the content of unbound fat in the leather, the limit of tensile strength and elongation at a stress of 10 MPa was revealed. Good elastic-plastic properties and no difference between the strength of the test skins as a whole and their front layer indicate a more even distribution of materials in the structure of the dermis. This correlates with the results of microscopic studies and allows predicting an increase in area yield, that is, a more rational use of scarce leather raw materials. The results of the work will be used in further studies devoted to the optimization of the parameters of the technology of liquid finishing of natural leather.

Use of enzymatic processes in the tanning of leather materials

Abstract The policy of sustainable development, the need to save natural environmental resources, and the use of waste as raw materials in new production processes allow the use of enzymes in many industries. Enzymatic tanning and chrome tanning are two different methods used in the leather industry to transform raw hides into a durable and usable material. Enzymatic tanning uses natural enzymes that are biodegradable and environmentally friendly. Additionally, enzymatic tanning requires less water and generates less waste than chrome tanning. Moreover, enzymatic tanning can result in softer and more flexible leather with better uniformity. Enzymes selectively break down collagen fibers, resulting in a more even tanning and a consistent leather product. The use of combined enzymatic technologies with non-obvious leather finishing methodologies in tanning is forced by European Union regulations limiting the use of hazardous substances and generating significant amounts of corrosive wastewater for the environment. However, tanning with enzymes is not a perfect process; therefore, this work presents the advantages and disadvantages of tanning with enzymes and describes new technological trends in the tanning industry.

Multifunctional leather finishing vs. applications, through the addition of well-dispersed flower-like nanoparticles

In the present paper, multifunctional flower-like nanoparticles were synthesized to be used in the leather finishing. They are capable of conferring simultaneously and synergistic antimicrobial, self-cleaning, light resistance, hydrophobic, mechanical, thermal, and fluorescent properties due to the presence of Ag, TiO2, and SiO2 NPs. These nanoparticles form a “flower-like” structure in which the “pistil” is made up of TiO2 and the “petals” that surround it of silver nanoparticles and silica nanoparticles, whose dimensions are of the order of ten nanometers. Their surfaces enjoy abundant hydrophilic functionalities to be dispersed within inks commonly used during the leather finishing process. Leathers functionalized with these nanomaterials showed significantly improved self-cleaning properties after 15 h of exposure to UV light, and antibacterial properties 10 times higher than that shown by the untreated samples. Aging tests were performed (ISO 105-B02, ISO 17228, SAEJ 2412). ΔE, color variation decreased by approximately 30%, if compared with samples not refined with flower-like NPs. Furthermore, the results of the mechanical tests (ISO 17076, FCA 50444) evidence amazing properties, e.g. abrasion resistance more than significantly improved, increase in resistance from 1500 cycles for the untreated samples to 3000 cycles for the leathers finished with flower-like NPs. The contact angle analysis, capturing the angle that traces the air–water to water–substrate interface from the origin of the air–water-substrate contact point at the edge, is practically unchanged after 10 s in the case of nanoparticles containing finishing.

Pickering emulsion approach: A novel strategy to fabricate waterborne polyurethane with enhanced abradability and water-resistance comparable to that of solvent-based coating

The urgent requirement of replacement for solvent polyurethane (PU) makes waterborne polyurethane (WPU) coating more attractive and popular in many industrial areas. However, the simultaneous realization of good dispersion stability and high performance of the cured films especially water resistance remains challenging. Herein, we propose a novel and facile Pickering emulsion approach to fabricate WPU with enhanced abradability and water-resistance comparable to that of solvent-based PU coating. In this approach, the hydrophobic polyurethane synthesized by poly-addition reaction in ethyl acetate is directly dispersed into water with SiO2 nanoparticles as Pickering stabilizer followed by subsequent evaporation of the remaining solvent to obtain Pickering waterborne polyurethane dispersion (PWPU dispersion). The ability of SiO2 to stabilize emulsion can be modulated by hydrophobic modification with propyltriethoxysilane (PTS). SiO2 nanoparticles with an optimal PTS-grafting rate of 2.8 wt% enables the PWPU dispersion with excellent long-term, chemical, thermal, and freeze-thaw stability. The highly-transparent composite films with honeycomb structures are readily formed by casting PWPU dispersion at room temperature. The thermal and mechanical properties of PWPU films are comparable to or superior to solvent-borne polyurethane (SPU) and self-emulsifying waterborne polyurethane (SWPU) films. Moreover, the water absorption of the PWPU-5 film is approximately 20 times lower than that of SWPU, demonstrating the excellent water-resistance. We further validated the coating performance of PWPU for leather finishing. The hydrophobicity, abrasion resistance and water vapor permeability of PWPU-coated leather are superior to those of SPU and SWPU-coated leather.

Application of some Plant Extracts as Biocolorants for Leather During Finishing Process

In this research, chrome-tanned bovine crust leathers were dyed during the finishing process using plant extracts: walnut shell (Juglans regia), oak bark (Quercus cortex), and onion peel (Allium cepa). In this study, the standard recipe applied by the factory was used in the leather finishing process. For this recipe, various plant extracts were used instead of pigments, and groups that did not contain pigment and any dyestuff were formed as the control groups. After these processes, color measurement analyzes were performed on Konica Minolta CM 3600d spectrophotometer. In order to investigate the effects of walnut shell (Juglans regia), oak bark (Quercus cortex), and onion peel (Allium cepa) on the other performance properties of leather, dry and wet rub fastness test according to standard method TS EN ISO 11640 (2001) was performed. The results of the study were statistically evaluated using the NCSS method (Number Cruncher Statistical System). As a result of the study, it was noticed that, depending on the extract, different colors were obtained. It was found that the dry and wet fastness of leathers treated with plant extracts improved.

Development of a New Collagen Gel Product for Leather Finishing.

Leather finishing is a critical process in the leather industry, as it significantly influences the final appearance, durability, and quality of leather products. Traditional leather finishing techniques often involve the use of synthetic chemicals, which may lead to environmental concerns and potential health hazards. In this study, we investigate the feasibility and effectiveness of a new collagen-based product for leather finishing. Collagen, a natural protein found abundantly in animals, has shown promise as an environmentally friendly and sustainable alternative for leather finishing. The new collagen gel product obtained from bovine hide waste by using an alkaline extraction method with lime was functionalized through an enzymatic treatment that allows to achieve a finishing product suitable for coating formulations, and at the same time, a biodegradable finishing. The collagen gel product was optimized by varying parameters, such as temperature, pH, and enzyme quantity. The optimized collagen gel product exhibits a wide particle size range and retains the triple-helical structure of collagen. The leather samples treated with the collagen gel product show enhanced properties compared to those with conventional finishes. The results show that the collagen gel product enhances water vapor permeability, color stability, and touch in the finishes. However, a low resistance to wet rubbing is obtained; therefore, it is necessary to study how to improve this parameter.

Increasing Functionality of Fish Leather by Chemical Surface Modifications.

Fish skin is a by-product of the fishing industry, which has become a significant environmental pollutant in recent years. Therefore, there is an emerging interest in developing novel technologies to utilize fish skin as a versatile raw material for the clothing and biomedical industries. Most research on finishing procedures is conducted on cattle leather, and practically very limited information on fish leather finishing is found in the literature. We have developed three functional surface finishing treatments on chromium (CL)- and vegetable (VL)- tanned salmon leather. These treatments include hydrophobic, oil repellent, and electro-conductive ones. The hydroxyl functional groups present on the surface of the leather were covalently grafted with bi-functional aliphatic small molecule, 10-undecenoylchloride (UC), by esterification reaction forming hydrophobic coating. The surface hydrophobicity was further increased via covalent binding of perfluorodecanethiol (PFDT) to the double bond end-groups of the UC-modified leather via thiol-ene click chemistry conditions. The oleophobic coating was successfully developed using synthesized fluorinated silica nanoparticles (FSN) and polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), showing oil repellency with a contact angle of about 100° for soybean oil and n-hexadecane. The electrically conductive coating was realized by the incorporation of conjugated polymer, polyaniline (PANI), via in situ polymerization method. The treated leather exhibited surface resistivity of about 5.2 (Log (Ω/square)), much lower than untreated leather with a resistivity of 11.4 (Log (Ω/square)).

Acrylic Finished Leather Upgraded with Thermoplastic Polyurethane Filament using 3D Printing – A New Generation Hybrid Leather of Synthetic and Natural Polymer

Leather manufacturing process involves a lot of waste disposal which pollutes environment, some of the processes are inevitable. In the present investigation, 3D printing technology was used to reduce the wastage and to cover defective regions in leather. The present study focuses on synthesis of acrylic binder using emulsion polymerization technique. These binders were analysed for solid content for better optimisation of the amount of binder to be utilised for finishing operation. The experimental binder was prepared with 26% solids. Particle size and thermogravimetric analyses were carried out to understand the size and shape of the particles and their thermal resistance. These binders were used for leather finishing and the performance of leather was studied. Surface morphology changes of leathers were studied using Scanning Electron Microscopy (SEM). Wet and dry rub fastness, finish film adhesion, light fastness and organoleptic properties were studied and found to be superior compared with control leathers. The acrylic finished leather with minor defects was taken for 3D printing and designed using Thermoplastic Polyurethane (TPU) as filament. The acrylic finished leather shows good adhesion for TPU and it results in numerous designs in short duration. The new additive was added to leather using 3D printing technology to produce a tailor-made valuable design without any waste disposal and chemical discharge. This invention may convert the rejected waste leather into valuable material and lead to the new generation hybrid leather for use.

Impact of Flax Seed Protein and Beeswax Emulsion Blend on Leather Finishing– A Novel Eco-Benign Formulation

Protein based finishing on leather surface is generally done using casein-based formulation which forms a transparent and breathable film. Other naturally available options such as protein extracted from flax seeds exhibit versatile application in various fields. Thus in this work, the flax seed protein which is found to be 84%, along with bees wax emulsion is explored for the first time as an Eco benign binder and as an alternative for casein based finish. The binders play very important role in leather finishing as it helps in binding the various constituents of finishing such as pigments, wax, and additives to the leather matrix. The prepared Eco benign binder formed a continuous film on the surface of the leather and improved the of physical properties and crack resistance of the leather. The FTIR and particle size analysis were carried out for the characterization of the Eco benign binder. The experimental leathers were tested for tensile strength, elongation at break, lastometer test, colour fastness and cold crack tests. The results of the said tests were satisfied and on par with control leathers.

Mechanically robust waterborne polyurethane with excellent room temperature self-healing and shape memory performance

Achieving severe damage restoration and the ideal combination of good mechanical properties and healing efficiency are two significant challenges for self-healing materials. In this study, a series of shape-memory, self-healing aqueous polyurethane (SMPU) were synthesized based on the molecular self-assembly design of 5-(2-hydroxyethyl)-6-methyl-2-aminuracil (HMA), 4-aminopyridine (4-APD) and polycaprolactone diol (PCL) moieties. The effects of HMA and 4-APD on mechanical properties, self-healing properties, and shape memory properties of SMPU were investigated. The dynamic crosslinking network generated by quadruple hydrogen bonds and multiple coordination bonds not only consumed strain energy but also promoted rapid re-formation after fracture, resulting in superior self-healing ability (healing efficiency 96.3%), excellent mechanical properties (tensile strength 39.1 MPa and elongation at break 908%) and recyclable capabilities of SMPU. Meanwhile, the SMPU showed a noteworthy shape memory effect; its shape fixation rate and recovery rate could reach 99% and 98%, respectively. The temperature and time dependence of the self-healing process were studied by molecular dynamics (MD), and the self-healing mechanism was clarified further. When SMPU was used for leather finishing, the finished and self-healing samples exhibited excellent wear resistance (wear rating: 4 ∼ 5). These advantageous properties endow SMPU with great potential applied value in leather and other regions.

Fabrication of poly (styrene-acrylate)/silver nanoparticle-graphene oxide composite antibacterial by in situ Pickering emulsion polymerization

Graphene oxide (GO) nanosheets decorated with silver nanoparticles (AgNPs) were easily synthesized by chemical reduction, and the prepared nanocomposite was then used as a stabilizer in the Pickering emulsion polymerization of poly (styrene-acrylate) to prepare PSA/AgNPs-GO composites. The AgNPs-GO nanocomposites were fully characterized by TEM, FTIR, Raman, SEM and XPS, which demonstrated that about 5–30 nm AgNPs with spherical, octahedral and cubic structures were decorated on the surface of wrinkled GO nanosheets. TEM photos and EDS spectrum of composites showed that the transparent GO nanosheets decorated with AgNPs were covered on the surface of PSA latexes and the AgNPs were uniformly dispersed on the surface of the PSA latexes without aggregation. The average diameter of composite latexes was obviously bigger than that of PSA latexes. However, the role of surfactant and the properties of hydrophilicity decreased the average diameter and WCA of composites while increasing the additions of AgNPs-GO nanocomposites. AFM images disclosed that wrinkled GO nanosheets decorated with AgNPs dispersed on the surface of composite films. XPS data proved clearly that silver was present only in metallic form and migration occurred during film-formation. TGA curves confirmed the composite film displayed better thermal stability than that of PSA. The results of antibacterial activity revealed that composite films had exhibited antibacterial properties against both E. coli and S. aureus, and the latter showed better antibacterial efficacy than the former. The nano-silver polyacrylate coatings with antibacterial activity explored in current work have wide application in the fields of wood coatings, leather finishing, and so on.

From Leather Wastes back to Leather Manufacturing: The Development of New Bio-Based Finishing Systems

The leather industry is currently between two opposing paths: on the one hand, recent legislative trends in terms of the eco-sustainability of industrial processes are leading leather manufacturing towards the development of cleaner production methods; on the other hand, the spread of new alternative materials to leather is driving the leather industry to improve its competitiveness by developing new innovative and high-quality products. Leather finishing is one of the most important phases of leather production, and is capable of improving its quality and organoleptic properties. However, this phase is characterized by the use of polluting chemical products, such as volatile organic compounds, potentially toxic crosslinking agents, and hardly biodegradable resins. In this context, this research work aims to develop a finishing formulation capable of giving leather the durability and quality properties required by the market, while at the same time, being eco-sustainable. Specifically, the aim of the present work is to suggest a new finishing formulation in terms not only of green technology but also of a circular production flow, by recovering solid leather wastes. The developed finishing system is based on the application of collagen, extracted from tanned wastes through an enzymatic treatment, to be cross-linked and bound to the leather surface. This new bio-based leather finish is compared to a resin-based leather finish, and shows the same quality standards as those requested by the market.

Application of Chromatographic and Microbiological Analyses to Identify and Assess the Durability of Antimicrobial Properties of Innovative Materials for the Footwear Industry─Leather Modified with Origanum vulgare Oil

A modification of the leather finishing technology in which the essential oil of Origanum vulgare is applied during the process of fatliquoring imparts antimicrobial activity to leather. This paper presents the characteristics of cowhide lining leather enriched with oregano oil (3%wt) in terms of durability of the antimicrobial activity conferred to it. Analyses carried out using gas chromatography–mass spectrometry have shown that carvacrol, the main component of oregano oil which is responsible for antiseptic action, constitutes more than 65% of the mixture of organic compounds detected in the vapor phase over samples of leather enriched with the oil even after 72 months of application. The results of an investigation into the kinetics of volatile compounds emission from leather samples treated with oil provided a proof that carvacrol emission decreased over time in an exponential way but did not fade out. This correlates with the results of microbiological analyses conducted using the agar plate diffusion method. The zones of growth inhibition obtained for the strains of microorganisms with sizes of 13 mm (Staphylococcus aureus), 1–3 mm (Candida albicans), and 2 mm (Staphylococcus epidermidis, Scopulariopsis brevicaulis) confirmed that the leather treated with oil still showed good activity against Gram-positive bacteria and fungi after 72 months of storage. The long-lasting antimicrobial properties of leather enriched with a natural biocide─oregano essential oil make it possible to be used in the production of special footwear intended for people with problems of the skin of the feet and toenails caused by pathogenic bacteria and fungi.

Study on Modification and Application of Functional Polyurethane in Leather Finishing

Over last few years, polyurethane (PU) has been applied in many fields by virtue of its mechanical strength, wear resistance, toughness, low temperature flexibility and other characteristics recently. To be more precise, PU materials can be screened through raw materials, improved formulas and so on to obtain the corresponding “customized” products. This gives the product “customizability” and further broadens the use of functional PUs. PU is one of the important coating materials in leather manufacture. This paper explores the academic research status of functional PU and its modification and application in leather production and leather finishing.

Osmanthus fragrance polyurethane/silkfibroin‐based double‐shellmicrocapsules for aromatic leather with sustained release fragrance

AbstractThe leather with the long‐lasting fragrance is critical for functional leather commodities but limited by poor temperature durability, low loading capacity and inferior flexural resistance. Herein, we develop a novel double‐shell fragrance release system via both interfacial polymerization and freeze inducement. Osmanthus fragrance (OF) was encapsulated with polyurethane (PU) and silk fibroin (SF), the double‐shell microcapsules with remarkable stability and enhanced sustained release property can be prepared. The OF@PU/SF microcapsules had well‐defined spherical shape with an average diameter of 5.21 μm measured by Scanning Electron Microscopy (SEM), which was larger than the single‐shell microcapsules (OF@SF) with the size of 1.70 μm. The thermogravimetric analysis (TGA) indicated that the OF loading capacity (LC) of OF@PU/SF microcapsules was 51.7%. Furthermore, the sustained release measurements by UV–vis absorption spectra clarified that 22.9% OF released from OF@PU/SF microcapsules during 30 days, lower than 36.7% of OF@SF microcapsules, much less than nearly 100% of free OF. Finally, the OF@PU/SF microcapsules were applied in leather finishing to efficiently improve the odour of the leather. The aromatic leather possessed sustained aroma with great stability enabling high temperature durability and flexural resistance property.

THE APPLICATION OF HYBRID PIGMENTS IN THE FORMATION OF A POLYMER-MINERAL COATING FOR LEATHER FINISHING

The paper is focused to the study of the physical and mechanical properties of a polymer-mineral coating based on hybrid pigments for leather finishing. The aim of this research is to study the effect of hybrid pigments based on montmorillonite on the formation of a polymer-mineral coating for leather finishing. Hybrid pigments obtained by complex modification of native montmorillonite with sodium carbonate and basic chromium (III) sulfate with further subsequent adsorption of anionic dyes on the cationic surface of the mineral particles were used for this research. A ready-made mixture of various structures film-formers, intended for the finishing of facial and polished leather was used as a film-former. For the leather finishing, coating paints were prepared in the form of polymer-mineral compositions by mixing hybrid pigments with a film-forming agent in the ratio, wt. part 1: 5. In this study it was calculated that montmorillonite consumption at the level of 1.5-2.0% in terms of the mass of montmorillonite from the mass of dry polymer residue was optimal for obtaining high physical and mechanical properties of polymer films for finishing leather. A mechanism for structuring the polymer matrix with a hybrid pigment was proposed. According to this mechanism the highly developed sorption surface of montmorillonite provided adsorption of the polymer and stabilized its structure with the formation of a mixed polymer-mineral composite. It was shown that the use of montmorillonite in the composition of hybrid pigment allowed to adjust the physical and mechanical properties of the polymer-mineral composition for leather finishing, provided an increase in strength and regulated the level of elasticity of the covering film, which ensured an increase in the operational properties of the leather coating.