Coextruded film is a multilayer film having peelable interfaces. The interfaces after separation expose a clean non-stacky surface. These peelable layers are created by multilayer polymer co extrusion. The structures can be made on conventional film processing equipment. The peelable interfaces of coextruded films can serve as renewable surfaces, removable coupons, tags, and cards, carrier webs, opening mechanisms and labels. The multi layer co extrusion can be designed for one or two side printing, post converting operation compatibility or for functionality. The layers of coextruded films can be pigmented or modified with other additives. The bond between the layers can be adjusted from low to high. Coextruded films also come as multilayer packaging films.
History of Coextruded Films
In 1985, Golden Eagle introduced coextruded films to bulk bun bakers. Replacing expensive cast films with co extrusions radically changed the industry, offering increased shelf life, productivity, and profitability. Co extrusions, designed to provide lower moisture vapor transmission rates allow the bakery products to retain freshness longer.
Features of Coextruded Films
- Cost effective transparent or opaque films
- Coextruded films have greater puncture resistance
- Reduced tear propagation
- Extra ordinary anti blocking and slip properties
- Coextruded films have excellent moisture resistance ability
- High seal integrity for longer shelf life
Science of Coextruded Films
Coextruded films use resin formulations for each layer to provide specific characteristics. When combined with a laminated support, the properties are magnified. A wide range of polymers like LDPE, LLDPE is used for making these multilayer
packaging films and a wide array of specialty resins. The most commonly used resins are:
- EVOH- High oxygen barrier
- Nylon- Strength plus oxygen barrier
- EVA- Flexibility and sealability
- Matallocene- Wide seal range
Resins with custom additives enhance film performance to fit the end use as well as the needs of converting and packaging systems.
Materials for Making Coextruded Film
Although it should be clear from the above discussion about the science of coextruded films regarding the raw materials, a list of materials used for making coextruded films is given below for better understanding. These are all typical plastic materials some of which are even biodegradable material. These materials are used by the coextruded film manufacturers for making coextruded films of 3, 5 or 7 plies.
-
PA (Polyamides or Nylon)
-
PE (Polyethylene)
-
PP (Polypropylene)
-
PS (Polystyrene)
-
PET (Polyethylene Terephthalate)
-
PVC (Polyvinyl Chloride)
-
ABS (Acrylonitrile Butadiene Styrene)
-
PC (Polycarbonate)
-
EVOH (Ethylene Vinyl Alcohol)
-
PLA (Polylactic Acid or Polylactide)
PLA is derived from renewable resources like corn starch; tapioca products including roots, chips or starch; and sugarcanes. It may be coextruded in a manner that it can become a biodegradable film under certain conditions, such as in the presence of oxygen.
Applications: Coextruded Films for Packaging
Natural film for cigarette packaging. Performs well in general overwrap applications. It is also used for bundling applications, surface print and non-print applications requiring improved puncture resistance. It is used as outer web in laminations for semi-free flowing products like pasta, candy, nuts in the shell. Used as laminations for bakery, snack and confectionery products. Some of the packaging products made using coextruded films are as follows:
Describe your requirements and get free best quotes from suppliers.