Section 1 of 8
Materials
What each film is, what it adds to the structure and where it is used: PET, BOPP, BOPA, PE, MOPE, EVOH, foil, paper, woven PP.
| Code | Material | What it is | Properties | Typical uses |
|---|---|---|---|---|
| PET | Biaxially oriented polyester | Polyethylene terephthalate film stretched in both directions; the most common outer layer in laminated flexible packaging. | High mechanical and thermal strength, dimensional stability and an ideal surface for reverse rotogravure printing; moderate moisture and oxygen barrier. Not heat-sealable on its own. | Printed outer layer of pouches and rollstock; the usual gauge is 12 µm. |
| Matte PET | Polyester with matte finish | PET with one matte side (coating or coextruded layer) that removes gloss without changing its mechanical properties. | Understated look and soft touch; keeps the strength and printability of PET. Allows matte and gloss areas to be combined with a registered varnish. | Outer layer for premium presentations: pet food, coffee, supplements, specialty flours. |
| VMPET | Vacuum-metallized PET | PET onto which a very thin layer of aluminum is deposited under vacuum. | Significantly improves oxygen, moisture and light barrier compared with clear PET; metallic appearance. Used as a middle layer, protected by the outer PET or BOPP. | Barrier structures for coffee, powders, supplements and snacks: PET/VMPET/PE, BOPP/VMPET/PE, matte BOPP/VMPET/PE. |
| AlOx PET | Aluminum-oxide-coated PET | PET with a transparent aluminum oxide layer deposited under vacuum. | High oxygen and moisture barrier while remaining transparent; withstands retort in structures designed for it and does not interfere with metal detectors. | Transparent retort pouches (ALOX PET/BOPA/RCPP) and products where the contents must be visible with a high barrier. |
| BOPP | Biaxially oriented polypropylene | Polypropylene film stretched in both directions; clear, glossy or pearlized. | High clarity and gloss, good moisture barrier, low oxygen barrier, good stiffness and low weight per m². Lower heat resistance than PET. | Printed outer layer for snacks and cookies, BOPP/VMBOPP rollstock, and lamination of woven PP bags. |
| Matte BOPP | Matte biaxially oriented polypropylene | BOPP with a coextruded matte layer on one side. | Paper-like, non-glossy finish; same barrier and strength as glossy BOPP. | Outer layer of pouches and rollstock with a matte look: matte BOPP/PE white, matte BOPP/VMPET/PE white. |
| VMBOPP | Metallized BOPP | BOPP with a vacuum-deposited aluminum layer; available in a heat-sealable version. | Improves moisture and light barrier and, to a lesser degree than VMPET, oxygen barrier. Metallic appearance and low weight. | Sealable inner layer in BOPP/VMBOPP rollstock for snacks and cookies; middle layer in BOPP/VMBOPP/woven PP bags. |
| BOPA | Biaxially oriented polyamide (nylon) | Nylon film stretched in both directions. | Very high puncture, tear and flex-crack resistance; good oxygen barrier that decreases with humidity; withstands retort temperatures. Always laminated between other layers. | Middle layer in retort, vacuum, frozen and heavy or sharp products: PET/ALUMINUM/BOPA/RCPP, PET/BOPA/PE white, BOPA/PE white. |
| PE / white PE | Polyethylene (sealant layer) | Polyethylene film (LDPE, LLDPE or blends), clear or white-pigmented. | Sealant layer: good seal strength at moderate temperature; flexible; medium moisture barrier and low oxygen barrier. White gives an opaque background and blocks part of the light. | Inner layer of almost every lamination; its gauge accounts for much of the stiffness and strength of the package. |
| MOPE | Machine-direction oriented polyethylene | Polyethylene stretched in the machine direction, which gains stiffness and stability so it can be printed and laminated as an outer layer. | More stiffness, strength and thermal stability than conventional PE; printable surface for rotogravure. Enables structures where every layer is polyethylene. | Outer layer of mono-material structures: MOPE/PE/PE white and MOPE/PE/EVOH PE. |
| CPP / RCPP | Cast polypropylene / retort grade | Polypropylene extruded flat (cast). RCPP is the grade formulated to withstand autoclave sterilization. | Sealant with higher heat resistance than PE, good clarity and stiffness. RCPP holds its seal through retort at 121–135 °C (250–275 °F). | Sealant layer of retort pouches (PET/ALUMINUM/BOPA/RCPP, ALOX PET/BOPA/RCPP) and of structures exposed to heat. |
| EVOH | Ethylene vinyl alcohol | High oxygen-barrier resin coextruded as a thin layer inside a PE film. | One of the best oxygen barriers among polymers under dry conditions; loses barrier with humidity, which is why it is protected between PE layers. Transparent. | Barrier layer in PET/EVOH PE and in the recyclable option MOPE/PE/EVOH PE. |
| Aluminum foil | Aluminum foil | Thin metal foil; in flexible packaging it is normally used between 6 and 9 µm. | Nearly total barrier to light, oxygen and moisture; opaque; withstands retort. Thin gauges may have pinholes and crack with repeated flexing, which is why foil is laminated between PET and a sealant layer. | Retort, coffee, pharmaceutical, powders and long-shelf-life products: PET/ALUMINUM/PE white, PET/ALUMINUM/BOPA/RCPP. |
| Kraft paper | Kraft paper | Fiber-based paper, natural or bleached, in packaging basis weights. | Natural look, stiffness and printability; it has no barrier by itself and absorbs moisture, so it is laminated to PE or combined with woven PP. | Outer layer in kraft/PE for a natural presentation and a layer in paper-laminated woven sacks (BOPP/WOVEN PP/PAPER) for construction. |
| Woven PP | Woven polypropylene fabric | Fabric woven from flat polypropylene tapes; specified by tape denier and weave density (tapes per inch). | Very high tensile and tear strength at low weight; no barrier on its own. Accepts lamination with printed BOPP or paper, and an inner liner. | Bags from 5 to 50 kg (11 to 110 lb): pet food, grains, sugar, fertilizers and construction materials. |
| PE liner | Polyethylene inner layer | PE film placed inside the woven bag, loose or laminated, as a containment layer. | Adds moisture and dust barrier, hermeticity and the ability to heat-seal the inside. | Woven bags for hygroscopic or fine products: flours, chemicals, pet food with grease control (BOPP/COEX/WOVEN PP/PE LINER). |
| Coextrusion | Coextruded multilayer film | Process in which several resins are extruded at the same time and exit as a single film of 3, 5 or 7 layers. | Combines sealing, strength and barrier (for example EVOH) in one film without additional laminations; allows grease-control layers. | Multilayer PE sealant, EVOH films and the COEX layer of woven bags for greasy feed. |
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