Leather finishing agent is a general term for leather auxiliaries used for leather surface finishing protection and beautifying leather. It is prepared from film-forming materials, coloring materials, solvents and auxiliaries according to a certain proportion. The film-forming materials are leather finishing agents. Foundation. Leather finishing agents also play a very important role in the leather manufacturing industry, which can increase the beauty of leather, prolong the use of leather, significantly improve the quality and grade of leather products, and increase the trade value. With the change of consumer concept and the introduction of environmental protection issues, people have put forward higher requirements for finishing agents. Therefore, there have been many researches on leather finishing agents in recent years. The following is a review of the research progress of leather finishing agents at home and abroad. . High Mast Lighting Pole With Lifting System High Mast Lighting Pole With Lifting System,Stadium High Mast Light Pole Tower,Lighting Pole With Lifting System,Stadium High Mast Light Pole Yangzhou Langxu Lighting Technology Co., Ltd , https://www.street-lighting.com
Traditional leather finishes and advances Casein is the earliest leather finish used and has a long history. Casein is a substance extracted from milk. Due to the use of casein to coat it, it is hard, non-extensible, easy to break, strong in water absorption, not resistant to wet rubbing, and extracted from milk does not meet the development requirements, so it is improved or replaced with synthetic polymer. Nitrocellulose solution (nitrocellulose) was officially applied to leather finishing agents in 1920 and commercialized. Nitrocellulose can increase the water resistance of coatings as a surface brightener. However, the nitrocellulose-based finishing agent is not resistant to aging, and the plasticizer is easily volatilized during use, so that the coating becomes hard and brittle, and the coating will be yellow under ultraviolet light irradiation. Therefore, the nitrocellulose-based finishing agent is modified in the leather. It has never been widely used.
In 1933, acrylic emulsions were first used in leather finishing in Germany and quickly gained application. Acrylic resin finishing agent has unique properties compared with natural resin and other synthetic resins. It has strong synergy with skin collagen, high film forming strength, elasticity, weather resistance, excellent aging resistance, low cost and good leather. Physical property. However, the acrylic emulsion is a thermoplastic resin, and its coating film has the disadvantages of "hot tack, cold brittleness" and resistance to solvents, which limits its use. Polyurethane, also known as polyurethane, is a polymer compound formed by the action of polyisocyanate and polyhydroxy compound. It is characterized by a large number of repeating urethane groups on the macromolecular chain. Therefore, it has a good Strength, abrasion resistance, solvent resistance, etc., and the properties of the polyurethane can be adjusted in a wide range by changing the structure and molecular weight of the compound. Polyurethane is used as a leather finishing agent. It has good film-forming properties and strong bonding. The coating has high gloss, high abrasion resistance, high elasticity, water resistance, weather resistance, cold resistance, heat resistance and chemical resistance. The finished finished leather is full. Comfortable, can greatly improve the grade of finished leather. In the early 1960s, polyurethane was first used in leather and was exchanged at the 5th International Leather Conference. Originally used only for patent leather, it was a one-component moisture cure, followed by the development of many solvent-based finishes, such as a single group. Sub-active polyurethane and the like. In order to further improve the performance of polyurethane finishes, a large number of studies on polyurethane finishes have been conducted at home and abroad. In 1967, waterborne polyurethane realized industrial production. In 1972, Bayer Company of Germany took the lead in developing waterborne polyurethane leather finishing agent. After the 1980s, BaSF of Germany developed the as-tacinFinishPUD series, and Fenice of Italy developed the UW series of waterborne polyurethane leather finishing agents. The application of polyurethane in China's leather industry began in the 1970s. The earlier finishing agents were PU-1 of Tianjin Leather Research Institute, PU-2 of Shenyang Leather Research Institute and PU series of Chenguang Research Institute of the former Ministry of Chemical Industry. Since the 1980s, the research on domestic water-based leather finishing agents has made great progress, especially after the “Eighth Five-Year Plan†and the “Ninth Five-Year Planâ€, the variety of polyurethane finishing agents has been increasing and the performance has become better and better.
UV-curing leather finishing agent Progressive photocuring coating is an energy-saving and environment-friendly coating developed by Germany in the late 1960s. After being exposed to ultraviolet light, the coating develops a photochemical reaction, which causes the coating to rapidly polymerize and crosslink. Curing of the coating. The traditional heat-curing leather finishing agent not only has low production efficiency, high environmental hazard, but also greatly limits the export of leather footwear products to foreign trade. Compared with other types of coatings, UV-curable coatings have fast curing speed and save energy. The advantages of green environmental protection are gradually gaining people's attention.
The application of light-curing coatings to leather surfaces began in the 1970s. At the American Leather Chemists' Association meeting in June 1977, Buechler first proposed the idea of ​​radiation-cured leather finishing agents and explained their advantages. In September of the same year, at the 15th Leather Technology Experts and Chemists Society in Hamburg, Germany, Knight and Marriott also proposed the same topic. 1978 Canadian Eagle Ottawa Leather Company, 1981 Australia Unisearch Company, 1982-1989 Frank Scholnick, Philadelphia, Pennsylvania, Peter R. Buechler and Helena.Gruber, 1995-2002 Pakistan and Science and Engineering Research Institute, Beijing Yingli Technology companies, LangroChemie in Germany in 2002, FeniceSPa in Italy in 2002, Hunan Asia University Co., Ltd. in 2003, School of Materials Science and Engineering, Beijing University of Chemical Technology, and WOEI-KaEHUaNG in Taipei, China, all conducted research on light-curing leather coatings. . The School of Materials Science and Engineering of Beijing University of Chemical Technology systematically studied the research of colored system light-curing leather coating, water-based light-curing leather coating and nano-modified light-curing leather, and successfully applied light-curing leather coating to the surface of leather shoes. After testing, the photocurable leather coating has both good coating properties and maintains the permeability of the leather.
The basic composition of UV leather coating is compared with the traditional leather glazing process. The solvent volatilization of the light-curing coating leather coating is greatly reduced, and the fire hazard is reduced. The most important thing is that the curing speed of the coating is greatly improved, and there is no need to dry the space. The drying time has been shortened from the past few hours to less than one minute. Light-curing leather coatings can be used on the leather or on artificial leather. The obvious environmental protection, high efficiency and high performance of light-curing leather coatings have become the common name in the field of leather finishing. It is foreseeable that research and application of light-curing leather finishes will become popular.
Summarizing the above development process, the development trend of leather coatings has the following aspects: 1 water-soluble finishing agent gradually replaces solvent-based finishing agent; 2 single coating agent develops to composite and multi-functional finishing agent; 3 water-soluble polyurethane coating agent will occupy Dominant; 4 towards the development of UV light curing finishes.