Lamination extrusion

Current usage is almost entirely associated with the good adhesion to aluminium. Specific applications include the bonding of aluminium foil to plastics films, as the adhesive layer between aluminium foil and polyethylene in multilayer extrusion-laminated non-lead toothpaste tubes and in coated aluminium foil pouches. Grades have more recently become available for manufacture by blown film processes designed for use in skin packaging applications. Such materials are said to comply with FDA regulations. 

Material Family Injection Compression Hansfer Casting Cold Molding Coating Structural Foam Extrusion Laminating Sheet Forming RP Molding FRP Filament Dip and Slush Blow Rotational... 

Figure 18.2 Example of an extrusion laminator with auxiliary equipment...

Other processes for bonding of multi-layer structures include extrusion and co-extrusion lamination. Extmsion lamination involves extruding a thin layer... 

Use Food packaging, sporting goods, wire and cable, building construction and automotive. More recent uses are extrusion laminations, in extrusion coatings, and as adhesive films and webs for thermal laminating and other new uses not related to packaging. 

Nucrel [DuPont]. TM for an ethylene-meth-acrylic acid copolymer resin available for use in conventional extrusion coating, coextrusion coating, and extrusion laminating equipment designed to process polyethylene resins. Higher melt flow index results in fewer resin leaks. 

A high extrusion temperature, followed by corona treatment which causes oxidation, was used for the PE layer of the cartons, whereas the PE liner for the "bag in the box" is a LDPE extruded at a lower temperature and without corona treatment. This study, therefore, indicates that an oxidized polymer surface may accelerate reactions resulting in a reduced shelf-life. These results were confirmed by Durr (10) who presented the effect of high temperature extrusion lamination of an Ionomer on development of off-flavors. In recent years carton packs are coated with an additional layer of low temperature extruded PE in order to reduce the above effects. 

Mylar . [DuPonf DuPont UK] Petiyes-ter film dansparent, strong film for pkg. foods, adhesive and extrusion laminations, vacuum metallizing process, as core wrap and insulation for telecommunications and power cable applies. 

Primacor. [Dow] Adhesive copolymers for blown film, extrusion coatings, adhesive extrusion laminates for flexible pkg. structures, coatings, inks, adhesives. 

A scheme of appl3dng an inhibited coating in a polymer melt onto the film base by extrusion lamination [34] is illustrated in Fig. 2.13. A similar procedure is employed at Cortec and Northern Instruments Co. for paper production with a laminated layer of inhibited PE. 

Fig. 2.13. Extrusion-lamination scheme for production of two-layered inhibited polymer film materials (1) unwinding machine (2) film base, (3) extruder with a slot head, (4) inhibited polymer composition, (5) pinch roller, (6) cooling shaft, (7) coiler...

In the first operation, the paper and the foil are extrusion laminated using an acid copolymer as the adhesive. Next, the sealant layer is applied as an extrusion coating. The operation can be accomplished in two passes, or in a single pass in a tandem extrusion line as shown in Fig. 8.2. In such a line, both extrusion heads are usually capable of coextrusion, as well. To understand the process of extrusion coating and laminating, it is necessary to start with the process in its simplest form, which, by the way, is how it is still practiced today by some converters. 

Hot melt laminating is a close relative of extrusion laminating. This process uses a lower molecular weight adhesive polymer that does not need an extruder to melt and pump it. The material s viscosity in the molten state can be low enough for... 

Now that we have discussed the processes that can be used to create multilayer structures, coating, coextrusion, and lamination, the question arises, which process should be used, and when Liquid adhesive systems usually run faster than extrusion laminating and coating systems. If one is using a solvent-based system, there is the issue of whether or not any residual odors that might affect the product to be packaged remain. Water-based systems do not have solvent odors, but they are not necessarily odor-free. 

Extrusion laminations are obviously used to create structures containing paper and foil, but extrusion laminating can be done to join two polymer films, also. One... 

Discuss the similarities and differences between extrusion laminating and hot melt laminating. 

Many substrates, including paper, paperboard, cellulose film, fireboard, metal foils, or transparent films are coated with resins by direct extrusion. The resins most commonly used are the polyolefins, such as polyethylene, polypropylene, ionomer, and ethylene-vinyl acetate copolymers. Nylon, PVC, and polyester are used for a lesser extent. Often combinations of these resins and substrates are used to provide a multiplayer structure. [A related technique, called extrusion laminating, involves two or more substrates, such as paper and aluminum foil, combined by using a plastic film, (e.g., polyethylene) as the adhesive and as a moisture barrier.] Coatings are applied in thicknesses of about 0.2-15 nuls, the common average being 0.5-2 mils, and the substrates range in thickness fi om 0.5 to more than 24 mils. 

The first part of the following text describes the development of laminations during the extrusion process and under which aspects these can be classified. This is followed by a description of qualitative as well as quantitative methods to proof and evaluate laminations. The last section of this chapter details some possible methods for the minimisation of extrusion laminations and how their negative effects may be avoided. The bibliography is restricted to the essentials information regarding further literature can be taken from the bibliography. 

During extrusion laminations basically develop as a result of the combined effect of raw material respectively body-specific characteristics and physical processes caused by transport, homogenisation and shaping operations within the extruder, which may cause shearing, gliding, separation and rejoining effects within the ceramic body. 

It is appropriate to first of all look into optimisation of the plastic body in regard to minimising laminations. Certain materials are particularly unfavourable and tend to the formation of extrusion laminations. These are those body compositions which contain a high percentage of extremely fine and anisomorphic particles, mainly clays and kaolines with a proportion of clay minerals, whereby the lamination problems have a tendency to increase as the specific surface is enlarged. But also other materials like talcum or micaceous natural raw materials with lamellar particles are prone to the formation of extrusion laminations. 

PEA is well known for its use in conventional extrusion coating, co-extrusion coating, and extrusion lamination [105]. The beneficial properties of PEA, such as excellent adhesion to various substrates such as foils, paper, and films, can add value to other polymers that require these properties for specific apphcations. PEA/LDPE blends have many industrial uses because of their good mechanical strength, processability, and impact strength. 

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