English
In order to meet the needs of some special functions of plastic film packaging materials in the production process, a variety of characteristic materials (such as breathable, waterproof, thermal insulation, toughness, etc.) are blown and co-squeezed together to form a multi-functional plastic film, and a multi-layer co-extruded film blowing machine is developed. The purpose of the multi-layer co-extruded film blowing machine is to play the advantages of a variety of materials and avoid some shortcomings of a single material or a single layer film blowing machine. For example, the co-extruded film blowing machine of PP and PE, it is the combination of the characteristics of high hardness of PP material and the characteristics of high brightness of PE material to produce a film with two characteristics.
The seven-layer co-extruded blowing film unit is mainly suitable for HDPE, MHDPE, LDPE, LLDPE, MLLDPE, PA, EVOH and other resins with gas barrier properties. The film produced is mainly used for packaging materials such as heavy packaging, food bags, vacuum bags, liquid bags, etc. To achieve the purpose of preserving fragrance, keeping fresh, anti-corrosion, airtight and extending shelf life. The produced films have high transparency, puncture resistance, high toughness, good low temperature heat, good composite fastness and anti-curling property. Compared with similar equipment, it has the advantages of higher output, good plasticization of products, low energy consumption and easy operation, and completely solves the problems of film flanging and winding size, so that product quality has reached a new level. This film can be widely used in light and heavy packaging because of its good barrier, freshness, moisture, frost, oxygen and oil resistance. Such as all kinds of fresh fruits, meat, pickles, fresh milk, liquid drinks, medical supplies, etc.
Polymer multilayer composite film has the advantages of light weight, insulation, chemical corrosion resistance, easy molding and processing, and some polymers have elasticity, transparency, beautiful and other special properties, so it is widely used in industrial and agricultural production, transportation, medical, national defense and daily life.
The mechanical strength and surface hardness of single-layer film are low, and the shortcomings of flammability and heat resistance limit its scope of use. Under the long-term action of environmental factors such as sunlight, temperature and humidity, and mechanical stress, the performance of the polymer gradually deteriorates, which is called "aging", and the color of the polymer becomes dark, the surface cracks, and the mechanical strength and electrical insulation performance are reduced. Single-layer film is difficult to overcome the above shortcomings, in order to better meet the use of products and processing performance, as well as appearance and other aspects of the special requirements, multi-layer composite film came into being.
There are many forming methods of multilayer composite film, but in general, it is mainly divided into: coating method, lamination method and multilayer co-extrusion method; At present, the development of foreign co-extrusion technology is rapid, especially some developed, the amount of multi-layer co-extrusion composite film has accounted for more than one-third of the total production of the film, and China's annual output of co-extrusion composite film is only about 50,000 tons, the amount of less than 10% of the total production of packaging film. Food needs a beautiful package, durable and beautiful.
