The material of the seven-layer co-extruded film is made of environmental protection raw materials (EVOH, PA, PET, PP, PE) once co-extruded, it has excellent gas resistance, moisture resistance, aroma protection, odor prevention, etc., it has the barrier property of metal, and makes up for the lack of metal susceptible to acid, alkali and other corrosion, both the paper portability, but also make up for the paper susceptible to moisture defects, It has good gas barrier performance, can better prevent water vapor intrusion, and excellent processing performance, convenient heat sealing, random modeling, has a certain mechanical strength and chemical corrosion resistance, in line with the hygiene standards of packaged food. Seven-layer coextruded high barrier vacuum packaging film series, can be added to the packaging material ultraviolet inhibitor or through printing, coloring to achieve the preservation of products.
The price of seven-layer coextruded high barrier vacuum packaging film is the same as that of composite film packaging, which is lower than that of composite packaging, and has great advantages in cost performance and broad market. The seven-layer co-extruded film has excellent printability and a variety of packaging forms, including three-side sealing type, self-supporting bag type, folding type, etc., which has a unique effect.
High temperature tensile film structure PA\TIE\PA\TIE\PP\PP\MPP Good barrier property, excellent heat sealing performance, 121° high temperature cooking. Application: Meat products, fish, seafood packaging
Low temperature stretch film structure PA\TIE\PA\TIE\PE\PE\MPE good water vapor barrier, good heat sealing, 100° low temperature cooking, application: low temperature meat products, dried beans, ezo, packaging.
Multi-layer co-extruded barrier film is generally produced by multi-layer co-extruded blow-molding process or casting process, a film forming process technology, multi-layer co-extrusion has excellent barrier properties, mechanical properties, tensile forming properties and heat sealing properties, and there is no need for additional compounding during the processing process, nor does it involve printing ink, adhesive and auxiliary residue problems, etc. Therefore, it is a relatively green environmental protection and cost advantage of food packaging technology.
Multi-layer co-extruded barrier film refers to the use of more than 3 extruders, the resin raw materials with different functions such as: polyethylene, polypropylene, nylon, ethylene-vinyl alcohol copolymer, etc., distributed melt extrusion, through their respective flow channels in the multi-layer co-extruded die head confluence, and then after blowing molding or casting sheet molding cooling composite together, the multi-layer co-extruded film is made. In this way, the advantages of different resins are collected and designed, so that films with comprehensive performance can be produced to meet different packaging needs.
Characteristics of multilayer coextruded barrier films
Focus on the advantages of multiple materials
The multi-layer coextruded barrier film structure can combine materials with different properties according to the needs, so that it has multiple properties at the same time. For example, for heat sealing and packaging machinery, the film needs to have good machining properties, MDPE or HDPE material is used in the multi-layer structure, so as to improve the strength and stiffness of the film, to ensure good machining properties, and the inner layer uses good heat sealing performance of metallocene (HAO) polyethylene material, So that the film has good thermal sealing performance and mechanical properties, better meet the needs of packaging, and in order to meet the different barrier needs, you can choose PA, EVOH, PVDC to meet the different barrier needs of the film.
Cost control
Multi-layer co-extrusion barrier film technology is a multi-layer co-extrusion molding process, without the traditional composite, coating and other post-processing technology, can effectively reduce raw material costs and production processes, not only can save production costs, but also in the film thickness control can achieve thinning feasibility.
The structure of the film can be adjusted according to the need
The production of a variety of structure of the film, suitable for different packaging needs, through the structural design, the combination of a variety of materials, give full play to the characteristics of different raw materials, but also according to the needs of different packaging uses, different structural layer design. And the more the number of co-extruded layers, the greater the flexibility of the structure can be designed, and the multi-layer co-extruded film structure that has been applied on the market has reached a maximum of 11 layers, which has been exhibited in the K Exhibition conference in Germany in 2016. Because of the flexible design of multi-layer co-extrusion structure, high barrier film, medium barrier film and low barrier film can be processed. Different color barrier films are also produced according to different color masterbatches.
Wide range of use
Multilayer co-extruded film materials are suitable for all flexible packaging applications. Including food, daily chemical, beverage, medicine, electronic products, protective film and so on.
Structural design of multilayer co-extruded films
The structure of multilayer co-extruded films can be divided into two categories, namely symmetric structure (A/B/A) and asymmetric structure (A/B/C). At present, China's barrier films are mostly 5 layers, 7 layers, 8 layers, 9 layers (some foreign companies do 10 layers, 11 layers). The structure of the 5-layer co-extruded film is introduced as an example.
The symmetrical structural layer of the multilayer coextruded barrier film is composed of three types of functional layers: barrier layer, bonding layer and support layer.
Barrier layer: The barrier layer of its oxygen, moisture, prevent oil leakage and other effects, through the barrier layer material and thickness control, adjust the barrier performance of the film material, suitable for different packaging needs (the market commonly used barrier materials including PA, EVOH, PVDC, etc.). Various barrier materials can be applied individually to form high barrier and medium barrier series packaging films, and the sandwich structure formed by the combination of PA and EVOH has high barrier properties.
Support layer:
The general symmetrical structural material has two support layers, the inner layer is used for heat sealing, called heat sealing layer, and the outer layer is directly used as the outer layer of the packaging film or for printing to become the printing layer. The support layer requires good mechanical strength, heat sealing performance, water vapor resistance and transparency and printability, and the common material of this layer is LDPE or LDPE/LLDPE blend material combination.
Adhesive layer:
The role of the bond layer is to bond the barrier layer and the support layer to ensure the peeling force between the layers. The selection of the material and thickness of the bond layer is generally based on the material of the support layer and the barrier layer and the bonding strength to be achieved to determine the binder material used by the bond layer.
At present, the common structure in China has 7 layers, 8 layers, 9 layers and other barrier films, and now PE\PP represents the support layer material, PA represents the barrier layer material, and the multi-layer co-extruded film structure is explained.
Symmetrical structure barrier film
PE/Tie/PA/Tie/PE
Five or more multilayer co-extruded film equipment
PE/Tie/EVOH/Tie/PE
Five or more multilayer co-extruded film equipment
PE/Tie/PA/EVOH/PA/Tie/PE
Seven or more multilayer co-extruded film equipment
Asymmetric structure barrier film
PA/Tie/PE/Tie/PA/Tie/PE
Seven or more multilayer co-extruded film equipment
PA/Tie/PP/Tie/PA/Tie/PP
Seven or more multilayer co-extruded film equipment
PA/Tie/PE/Tie/PA/EVOH/PA/Tie/PE
Nine or more multilayer co-extruded film equipment
PA/Tie/PP/Tie/PA/EVOH/PA/Tie/PP
Nine or more multilayer co-extruded film equipment
It can be seen from the above structure that the co-extruded film structure of nine layers and more than one layer has great flexibility, but because the more layers, the more difficult the process is, the domestic multi-layer co-extruded film is generally controlled in 5-9 layers.
In recent years, with the continuous improvement of the performance requirements of plastic packaging films, multi-layer co-extruded barrier film technology has been well developed, it is expected that the future multi-layer co-extruded barrier film will develop to more multi-layer structures, and from the field of barrier packaging to more other fields.