Coated PVA barrier packaging film

Before understanding the PVA film production line, let's first get to know PVA, Chinese name polyvinyl alcohol. Polyvinyl alcohol is one of today's large-scale industrial production of synthetic resins, due to the extreme instability of vinyl alcohol, industrial production of polyvinyl alcohol are saponified by polyvinyl acetate (alcoholysis) and get, characterize the characteristics of polyvinyl alcohol indexes are mainly polymerization and saponification degree, polymerization degree indicates its molecular weight of the size of the degree of saponification is indicated in polyvinyl acetate acetyl by the amount of hydroxyl substitutions, commonly used in industrial production. Polyvinyl alcohol grade according to the saponification degree of different, 99%, 93%, 88% and so on several, it is not difficult to see, the application of polyvinyl alcohol, in addition to the saponification degree of 99%, can be regarded as polyvinyl alcohol copolymer, in fact, polyvinyl alcohol should be regarded as a copolymer of ethylene and vinyl acetate.

Open vinyl alcohol saponification degree of the size of the performance of polyvinyl alcohol has a great impact, such as water solubility, saponification degree of 88% of the largest degree of saponification of polyvinyl alcohol can be quickly dissolved in cold water, saponification degree of 93% of the water solubility of polyvinyl alcohol followed by the degree of saponification of 99% of the degree of saponification of the lowest degree of saponification of polyvinyl alcohol, insoluble in water at room temperature, only in the high-temperature conditions dissolved in water. Polyvinyl alcohol macromolecular chain, contains a large number of hydroxyl, can participate in all the typical chemical reactions of polyol, industrial production, polyvinyl alcohol is used in large quantities for filament extraction at the same time acetal processing, the production of nylon fibres, the other main role is the production of coatings and adhesives and textile processing with slurry.

The highly saponifiable polyvinyl alcohol molecular structure has a high degree of regularity and high polarity, and is easily crystallised as it has a high barrier to non-polar gases such as oxygen. Polyvinyl alcohol is currently industrialised plastic packaging materials in the best barrier varieties, is the production of barrier packaging materials, an ideal substrate. However, as a high barrier substrate, polyvinyl alcohol film has two major obvious defects, one is that polyvinyl alcohol film in high humidity conditions with high water absorption, in high humidity conditions will be a large number of water absorption, after the absorption of water film is easy to wrinkle, so that the subsequent composite and other processing difficulties, and the inhalation of water in the polyvinyl alcohol, the role of the plasticiser, so that the polyvinyl alcohol inter-molecular force decreased significantly, resulting in a significant decrease in the barrier performance of oxygen; the second is that polyvinyl alcohol is the best of the industrialized plastic packaging materials in the best barrier properties, is an ideal substrate for the production of barrier packaging materials. The second is the lack of thermal stability of polyvinyl alcohol, etherification and dehydration reaction occurs at 160 ° C, at about 200 ° C marked decomposition, the melting temperature is as high as 230 ° C or so, so can not be used in the conventional extrusion of thermoplastic film production process film, you must use the solution cast film method or with a large amount of water as a processing aids, and then extruded into the film.

After decades of development, the application of ordinary polyvinyl alcohol solution, crosslinking modified polyvinyl alcohol solution, nano-modified crosslinking polyvinyl alcohol solution and its coating process, through the modification of polyvinyl alcohol, finally solve the polyvinyl alcohol solution viscosity is high, easy to agglomerate coating inconvenience as well as the polyvinyl alcohol temperature resistance is poor, high humidity conditions, poor oxygen permeability of the barrier problem. At the same time, the coating process has been improved, from the initial reverse roller coating, to anilox roller coating, coating line speed from the initial 20m/min, increased to 150m/min or more, greatly reducing the production cost of high barrier polyvinyl alcohol coated film, completed the process of industrialisation of high barrier polyvinyl alcohol coated film.

Nanjing Suminoe Precision Machinery Co., Ltd. has professional cast film production line, the company's main cast film manufacturing production line: TPU hot melt adhesive film production line, CPP/CPE cast film production line, EVA solar energy encapsulation adhesive film production line, PE sanitary breathable film production line, PVDF cast film production line, PP three-dimensional film production line, blood purification film production line for medical use, multi-layer co-extruded film production line, LLDPE twisted film production line, LLDPE coextruded film production line, LLDPE co-extruded film production line. production line, LLDPE winding film production line and so on.

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