Comparison between 5th and 3rd floors
The barrier layer in a 5-layer composite film is usually located at the core,isolating it from moisture in the atmosphere.Because the barrier layer is located at the core,other materials can be used to significantly enhance the barrier performance.Nylon can be used in the core layer to enable the 5-layer structure with PE surface layer to cope with more materials similar to PE film and improve the process capability.Moreover,processors can use colorants in the outer layer without affecting the bonding or barrier layers.
3-layer composite films,especially those made of nylon,tend to curl due to their different physical properties in asymmetric structures.For a 5-layer structure,it is more common to use symmetric or near symmetric structures to reduce curling.The curling in the 3-layer structure can only be controlled by using nylon copolymers.In a 5-layer structure,processors can use nylon 6 to obtain a nylon layer with a thickness of approximately half that of a 3-layer film.This saves raw material costs while providing the same barrier performance and improved processing performance.
Comparison between 7th and 5th floors
For high barrier films,EVOH is often used as a barrier layer to replace nylon.Although EVOH has excellent oxygen barrier properties when dry,it rapidly deteriorates when wet.So,it is common to compress EVOH into two PE layers in a 5-layer structure to prevent moisture.In a 7-layer EVOH composite film structure,EVOH can be compressed into two adjacent PE layers and then protected with an outer layer of PE.This greatly improves the overall oxygen barrier and makes the 7-layer structure less susceptible to moisture.
Fragmentation or tearing may also be a problem for a 5-layer structure.Developing towards a 7-layer structure will result in the harder barrier layer being torn apart by the connecting thin layer into two identical layers.This maintains the barrier performance while giving the packaging greater resistance to breakage or tearing.Moreover,the 7-layer structure allows processors to tear open the outer layer to reduce raw material costs.More expensive polymers can be used as surface thin layers,while cheaper polymers can replace most of the previous surface layers.
Comparison between 9th and 7th floors
Generally,the barrier portion of high barrier composite films occupies 5 layers within the structure.Due to advances in polymer and processing technology,the percentage of overall thickness in the entire structure is continuously decreasing,while maintaining the same barrier properties.
However,it is still necessary to maintain the overall thickness of the composite film.Developing from the 7th floor to the 9th floor enables processors to achieve optimal mechanical,aesthetic,and cost performance.For high barrier films,the additional multifunctionality provided by 7-layer or 9-layer extrusion production lines may be considerable.The additional cost of purchasing a 7-layer or 9-layer extrusion production line compared to a 5-layer production line can have a payback period of less than one year.
The barrier layer in a 5-layer composite film is usually located at the core,isolating it from moisture in the atmosphere.Because the barrier layer is located at the core,other materials can be used to significantly enhance the barrier performance.Nylon can be used in the core layer to enable the 5-layer structure with PE surface layer to cope with more materials similar to PE film and improve the process capability.Moreover,processors can use colorants in the outer layer without affecting the bonding or barrier layers.
3-layer composite films,especially those made of nylon,tend to curl due to their different physical properties in asymmetric structures.For a 5-layer structure,it is more common to use symmetric or near symmetric structures to reduce curling.The curling in the 3-layer structure can only be controlled by using nylon copolymers.In a 5-layer structure,processors can use nylon 6 to obtain a nylon layer with a thickness of approximately half that of a 3-layer film.This saves raw material costs while providing the same barrier performance and improved processing performance.
Comparison between 7th and 5th floors
For high barrier films,EVOH is often used as a barrier layer to replace nylon.Although EVOH has excellent oxygen barrier properties when dry,it rapidly deteriorates when wet.So,it is common to compress EVOH into two PE layers in a 5-layer structure to prevent moisture.In a 7-layer EVOH composite film structure,EVOH can be compressed into two adjacent PE layers and then protected with an outer layer of PE.This greatly improves the overall oxygen barrier and makes the 7-layer structure less susceptible to moisture.
Fragmentation or tearing may also be a problem for a 5-layer structure.Developing towards a 7-layer structure will result in the harder barrier layer being torn apart by the connecting thin layer into two identical layers.This maintains the barrier performance while giving the packaging greater resistance to breakage or tearing.Moreover,the 7-layer structure allows processors to tear open the outer layer to reduce raw material costs.More expensive polymers can be used as surface thin layers,while cheaper polymers can replace most of the previous surface layers.
Comparison between 9th and 7th floors
Generally,the barrier portion of high barrier composite films occupies 5 layers within the structure.Due to advances in polymer and processing technology,the percentage of overall thickness in the entire structure is continuously decreasing,while maintaining the same barrier properties.
However,it is still necessary to maintain the overall thickness of the composite film.Developing from the 7th floor to the 9th floor enables processors to achieve optimal mechanical,aesthetic,and cost performance.For high barrier films,the additional multifunctionality provided by 7-layer or 9-layer extrusion production lines may be considerable.The additional cost of purchasing a 7-layer or 9-layer extrusion production line compared to a 5-layer production line can have a payback period of less than one year.
