Influence of polyurethane binders on the surface properties of finished leathers : Part 1 - Function as a sealing coat / Suriya Madhan in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIX, N° 7 (07/2024)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIX, N° 7 (07/2024) . - p. 295-302 Titre : Influence of polyurethane binders on the surface properties of finished leathers : Part 1 - Function as a sealing coat Type de document : texte imprimé Auteurs : Suriya Madhan, Auteur ; R. Monica Denise, Auteur ; Sujata Mandal, Auteur ; Swarna Vinodh Kanth, Auteur Année de publication : 2024 Article en page(s) : p. 295-302 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Adhésion Angle de contact Croûte (cuir) On entend par "cuir en croûte" des cuirs ayant subi les opérations jusqu'au tannage, à l'exclusion de toute opération de corroyage ou de finissage, mais qui, par opposition aux wet-blue ont été séchés. Cuirs et peaux -- Finition Cuirs et peaux -- Propriétés mécaniques Cuirs et peaux -- Propriétés organoleptiques Cuirs et peaux de bovins Energie de surface Essais dynamiques Etanchéité Liants Mesure Perméabilité Polyuréthanes Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Finishing is the final stage of the leather-making process, where the surface of the leather is enhanced to improve its durability, appearance, and texture. The sealing coat (used predominantly in corrected grain leathers for leather accessories and footwear industries) is the first step that forms the bottom layer of the leather finishing film before the base coat. The goal of the sealing coat is to keep the leather surface reactive and prevent the pigmented base coat from sinking completely into the grain of the leather. The chemicals used in the sealing coat provide the leather surface with a charge and condition (addition of oil/fat and/or polyurethane -PU) to ensure that the chemicals (pigments, binders, and other additives) used in the base coat of the finishing process are not completely absorbed into the grain layer of the crust leather. In the present study, the influence of PU as an additive to the sealing coat formulation was evaluated through measurement of surface properties, such as contact angle, surface energy, and work of adhesion. The values of the contact angle between the liquids (water/dimethyl sulfoxide/hexadecane) and the leather surface were used to evaluate the leather’s surface energy and work of adhesion. The water contact angle of the uncoated crust, cationic oil ground (COG)-coated crust, and COG-PU-coated crust was measured as 77.3, 93.6, and 109.0 degrees respectively. The increase in contact angle indicates an increase in the hydrophobicity of the leather’s surface on coating with COG and COG+PU. The surface energy component (γs) of the crust leather surface without coating, COG-coated, and COG-PU-coated leathers were 35.2, 28.3, and 24.8 m/Nm, while the work of adhesion of the above leathers for water were 88.8, 68.2, and 49.1 mJm-2, respectively. The experimental values indicated that PU plays an important role as an additive to the sealing coat and enhances the required properties in the finishing process for the desired final leather. Note de contenu : - EXPERIMENTAL SECTION : Materials - METHOD : Determination of contact angle - Measurement of work of adhesion and surface energy - Determination of wet and dry fastness - Determination of water-vapor permeability - Determination of physical strength characteristics - Measurement of adhesion of finish - Determination of organoleptic properties - RESULTS AND DISCUSSON : Contact angle and surface parameters of dyed crust, COG-coated and COG-PU-coated leather - Work of adhesion and surface energy of dyed crust, COG-coated leather, and COG-PU-coated leather - Relationship between work of achesion/surface energy and acidity/basicity of leathers coated with COG and COG-PU - Relationship between surface energy and polarity of leathers coated with COG and COG-PU - Water vapor permeability - The influence of COG and COG-PU coat on the physical organoleptic properties of finished leathers - Table 1 : Process of wet blue to black crust from cow hides - Table 2 : Process of sealing coat - Table 3 : Process of PU-sealing coat - Table 4 : Process of base and top coat after sealing/PU sealing coat - Table 5 : Contact angle, surface energy (ysv), acidity, basicity, polarity, work of adhesion (Wa) of dyed crust, COG-coated, and COG-PU-coated leathers - Table 6 : Finish adhesion, fastness to rub, and elongatio at break of dyed crust, COG-coated and COG-PU-coated leather - Table 7 : Organoleptic properties of the dyed crust, COG-coated and COG-PU-coated leather DOI : https://doi.org/10.34314/wdwj1p18 En ligne : https://drive.google.com/file/d/1J-_XLaKaV9az3xQYOPmWX42gVhsR-1lP/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=41283 [article]

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