Adhesive tie layer

Multilayer sheets containing poly(chlorotrifluoroethylene) and COC for blister packaging applications have been described (63). In the production of the multilayered film, the fluoropolymer layer is joined with the thermoplastic polymer layer and an adhesive tie layer. 

The adhesive tie layer can be made up from 82% ethylene-based octene plastomer, 15% styrene modified terpene resin and 3% of a styrene/isoprene/styrene styrenic block copolymer. 

Coextrusion produces multilayer laminates in a single process step. Two or more extruders feed different molten polymers into a multi-manifold die which layers them directly, or into a modular feedblock which layers them before feeding them into the die. This is used primarily in the packaging field, to sandwich an impermeable barrier layer between two commodity outer-film layers, and often includes adhesive tie layers to bond the barrier layer to the outer layers. 

Tie-layers are used as binding layers in some multilayer materials that are produced without any lamination adhesives. Tie-layers are formed by applying a co-extrudable resin, which is usually a polymer modified with active functional groups to make it adhere to the other substrates. 

Plexar . [< antum/USI] EVA or polyethylene-based resin adhesives tie-layer resins for coextruded pkg. 

The oriented films exhibit excellent adhesion between the 3GN and PET layers, eliminating the need for an adhesive tie layer. The oriented films are useful in end-uses requiring good oxygen-barrier resistance, such as food packaging applications. 

An interior adhesive tie layer, preferably an ethylene based copolymer with grafted functional groups... 

A significant disadvantage of wide multimanifold dies is difficulty in coextruding very thin layers, such as thin cap (surface) layers, or thin adhesive (tie) layers used to bond two dissimilar polymers. Often these thin layers represent only 1 or 2% of the total structure thickness and are therefore extruded at a relatively low rate. With wide dies it is difficult to obtain uniformity when extrusion... 

Hypalon CP 826. This is a chloriaated, maleic anhydride modified polypropylene having a chlorine content of about 25% and maleic anhydride content of about 0.8%, developed to promote adhesion of inks and coatiags to polypropyleae or bleads containing polypropyleae. It has a solutioa viscosity of 125 mPas(= cP) at 20% soHds ia xyleae and can be used ia dilute solutioas as a wash primer or a tie layer betweea materials that are difficult to adhere. CP 827 is a higher molecular-weight analogue with a solution viscosity of 280 mPas(= cP) at 20% soHds ia 80/20 xylene/methyl isobutyl ketoae. 

The coating is applied to protect the steel from corrosion due to the acid or alkaline condition of the soil surrounding the pipe in service. Usually, the process requires three layers. First, an epoxy powder is applied to achieve adhesion to the pretreated metal and therefore resistance to cathodic disbondment. Second, a tie layer of polyolefin copolymer is applied and third a thick layer of polyethylene is cascaded, which in effect protects the epoxy from physical damage. 

Adhesives and Sealants. Dominated by copolymers, adhesives and sealants remain somewhat of a specialty market. These polymers usually contain high copolymer content and low viscosity, and often require blending with oilier compounds prior to final application. Their uses are numerous, e.g., as seals for bottled drinks, as tie layers between incompatible polymers, or as automotive adhesives... 

PVDF can be coextruded and laminated, but the process has its technical challenges in matching the coefficients of thermal expansion, melt viscosities, and layer adhesion. Special tie-layers, often from blends of polymers compatible with PVDF, are used to achieve bonding.26-27... 

THV can be readily bonded to itself and other plastics and elastomers. It does not require surface treatment, such as chemical etch or corona treatment, to attain good adhesion to other polymers, although in some cases tie-layers are necessary. For bonding THV to elastomers an adhesion promoter is compounded to the elastomer substrate.35... 

When no bonding layers occur in a plastic laminated composite structure, a plastic tie-layer is used that provides bonding. Choosing the proper adhesive layer is by no means a simple task since evaluation includes processability, bonding capabilities, and performance in the final product. There are many different types with different capabilities, with EVOHs being one of the important ones. 

Nodax C4/C6 is said to be a natural fit for injection moulding and extrusion of sheet or film. The polymer has mechanical properties similar to a polyolefin and surface properties much like PET, including high receptivity to printing inks and dyes. Adhesion to LDPE and PP is good enough to avoid tie layers in multi-layer structures. Nodax s oxygen barrier property approaches that of EVOH. 

Polyamides and ethylene vinyl alcohol do not readily adhere to polyolefins, so a laminating adhesive or tie-layer is necessary to hold the coextruded stmcture together. Other polymers such as polycarbonate (PC) or polyethylene terephthalate (PET) are also used as outer layers in multi-layer stmctures. 

Examples of acid modified polyolefins are the copolymers of ethylene with acrylic acid or methacrylic acid. Variations include the partially neutralised acid copolymers with metal ions (ionomers) or terpolymers of ethylene, an acid and an acrylate such as methyl acrylate or isobutyl acrylate. Acid-containing extrudable adhesives are widely used to bond to aluminium foil. Examples of anhydride-modified polyolefins include terpolymers of ethylene, maleic anhydride and acrylates such as ethyl acrylate or butyl acrylate and the anhydride-grafted polyolefins. Some typical applications and stmctures of a variety of multilayer materials with extruded polymer tie-layer adhesives, as described in Du-Pont trade literature, are detailed in Table 16.2. 

Good adhesion to metals. Avatrel exhibits good adhesion (passes the cross-hatched tape test, ASTM D-3359-95a and IPG 650-TM) to metals such as Cu, Au, Al, Cr, Ti, and Si, as well as SiO2. Polyimides on the other hand require tie layers and adhesion promoters. 

Strong and rubbery. Frequently used as an adhesive or tie layer. Widely used as foams. 

Thermoplastic adhesives have to be used with limited product resistance. Some layer combinations do not require adhesives or tie layers. 

Multilayer films are generally extruded simultaneously through a single die. Adhesive polymers are often used as tie layers to join materials that do not exhibit strong adhesion to each other. 

Adhesion Properties Selar PA 2072 provides significantly better adhesion to EVOH blends than other grades of amorphous nylon do this may allow converters to employ less expensive adhesive resins in tie layers.f ]... 

---