EVOH film

日期:2019/6/19 9:30:00 / 阅读: / 来源:本站

EVOH film
Polyvinyl alcohol (PVA) is one of the materials with the lowest oxygen permeability in plastics at low humidity. However, due to its high hygroscopicity and high humidity, the oxygen permeability coefficient changes greatly. Therefore, as a food packaging material, Certain limitations, can not give full play to its specialty, at the same time, the decomposition temperature of PVA is below the melting point, so in the absence of plastic or in the absence of plasticizer, melt molding is difficult, so the PVA is modified, including olefins Copolymerization was mainly studied and discussed.
It has been found that as a comonomer, ethylene has the most excellent barrier property against oxygen and moisture resistance as compared with other olefins, and has good mold handling property.
Ethylene and vinyl alcohol copolymer (EVOH) resins are obtained by saponification hydrolysis of ethylene and vinyl acetate copolymer (EVA). The EVOH resin is excellent in gas barrier properties, aroma retention properties, oil resistance, chemical resistance, and transparency. In particular, gas barrier properties are one of the varieties of plastics with high gas barrier properties, and thus become a material for rapid growth in food packaging materials.
As a commodity, its application is later than PVDC. However, due to the above-mentioned high barrier property, good processability and recyclability, its film development, modification and application are very active, the dosage is increasing rapidly, and the demand for EVOH is expanding. As a food packaging material, the packaging materials that are discarded after use are environmentally friendly. In addition to food packaging, non-food packaging is also developing.
EVOH resin has good moldability, injection molding, extrusion molding, and multi-layer co-extrusion, casting and blow molding. For EVOH film, it is mainly multi-layer co-extrusion molding, tape casting, and extrusion biaxial stretching. In recent years, it has developed EVOH film.
EOH film has single layer and multi-layer composite film
The EVOH monolayer film has an EVOH cast film and an EVOH biaxially stretched film. These two types of single-layer films are mainly used as the main barrier layer of the dry composite and the main barrier layer of the extrusion coated film. The single-layer film processing is as thin as 15-20 um, which is bound to result in high cost. Therefore, a co-extruded composite film is developed, and the EVOH as a barrier layer can be as thin as 4-5 um, thereby greatly reducing the cost, and thus co-extruding EVOH. The development is faster.


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