25
2016
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07
Requirements for each layer of composite flexible packaging materials
Author:
Composite flexible packaging materials in the composite is actually the meaning of lamination, is the different properties of the film or other flexible materials bonded together, and then sealed, to carry, protect and decorate the purpose of the interior. The laminated structure of flexible packaging can be classified in many forms according to different combinations. However, the structure of the regular is usually distinguished by an outer layer, an intermediate layer, an inner layer, an adhesive layer, etc.
(I) outer material
The outer layer material is usually selected from materials with good mechanical strength, heat resistance, good printing performance and good optical performance. At present, the most commonly used materials are polyester (PET), nylon (NY), stretched polypropylene (BOPP), paper and other materials. The requirements and functions of the outer layer materials are shown in the following table:
| Requirements | Role |
| Mechanical strength | Tensile, tear, impact, friction |
| Barrier | Anti-humidity, anti-gas, anti-fragrance, anti-ultraviolet |
| Stability | Light resistance, oil resistance, organic resistance, heat resistance, cold resistance |
| Processability | Friction coefficient, thermal shrinkage crimp |
| Hygiene Safety | Low position, non-toxic |
| Gas | Gloss, transparency, shading, whiteness, printability |
(II) intermediate layer material
The intermediate layer material is usually used to enhance a certain characteristic of the composite structure, such as barrier, light shielding, fragrance retention, strength and other characteristics. At present, the most commonly used materials are aluminum foil (AL), aluminized film (VMCPP, VMPET), polyester (PET), nylon (NY), polyvinylidene chloride coated film (KBOPP, KPET, KONY), EVOH and other materials. The requirements and functions of the intermediate layer materials are shown in the following table.
| Requirements | Role |
| Mechanical strength | Tensile, tensile, tear, impact resistance |
| Barrier | Water barrier, gas barrier and fragrance protection |
| Processability | double-sided composite strength |
| Other | Transparent, shading |
(III) inner layer material
The most critical role of the inner layer material is sealing, and the inner layer structure is in direct contact with the inner object, so it is required to be non-toxic, tasteless, water-resistant and oil-resistant. Commonly used materials are cast polypropylene (CPP), ethylene-vinyl acetate copolymer (EVA), polyethylene (PE) and its modified materials. The requirements and functions of the inner layer materials are shown in the following table:
| Requirements | Role |
| Mechanical strength | Tensile, tensile, impact, pressure, stab, easy to tear |
| Barrier | Fragrance retention, low adsorption |
| Stability | Water resistance, oil resistance, heat resistance, cold resistance, stress cracking resistance |
| Processability | Coefficient of friction, hot tack, resistance to seal contamination, non-curling |
| Hygiene Safety | Low taste, non-toxic |
| Other | Transparent, non-transparent, anti-penetration |
(IV) adhesive layer
The function of the adhesive layer is to bond two adjacent layers of materials together to form a composite structure, and according to the characteristics of the adjacent materials and the composite process, an adhesive or an adhesive resin can be used as the adhesive layer material. The adhesive strength between the adhesive laminated materials is an important index to evaluate the intrinsic performance of composite packaging materials, and different packaging requirements for this index are not the same.
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