Polyethylene recommended adhesives

In general, adhesives recommended are similar to those used for polyethylene. Candidate adhesives include epoxies, polyamides, polysulfide epoxies, nitrile-phenolics, polyurethanes, and hot melts. ... 

Titanates have been instrumental in the bonding of fluorinated resins to packaging films, poly(hydantoin)—polyester to polyester wire enamel, polysulfide sealant to polyurethane (a phosphated titanate is recommended), polyethylene to cellophane using a titanated polyethylenimine, and silicone mbber sealant to metal or plastic support using polysilane (Si—H) plus polysiloxane (Si—OR) and titanate as the adhesive ingredients (450—454). Polyester film coated first with a titanium alkoxide, then with a poly(vinyl alcohol)—polyethylenimine blend, becomes impermeable to gases (455). 

Since slower-curing epoxy adhesives systems flow over and wet high-energy surfaces very well, there is little chance for air to become trapped at the interface. As a result, mechanical abrasion is often recommended as a substrate surface treatment prior to application of the epoxy adhesive. The added surface area and the mechanical bonding provided by the additional peaks and valleys on the surface will enhance adhesive strength. If the adhesive does not wet the substrate surface well, such as in the case of epoxy resin on polyethylene, mechanical abrasion is not recommended since it will only encourage the probability of gas voids being trapped at the interface. 

Polyethylene terephthalate cannot be solvent-cemented or heat-welded. Adhesives are the prime way of joining PET to itself and to other substrates. Only solvent cleaning of PET surfaces is recommended as a surface treatment. The linear film of polyethylene terephthalate (Mylar) provides a surface that can be pretreated by alkaline etching or plasma for maximum adhesion, but often a special treatment such as this is not necessary. An adhesive for linear polyester has been developed from a partially amidized acid from a secondary amine, reacted at less than stoichiometric with a DGEB A epoxy resin, and cured with a dihydrazide.72... 

Polyethylene and Polypropylene Acceptable bonds have been obtained between treated polyolefin surfaces with polar adhesives, such as epoxies, or solvent cements containing synthetic rubber or phenolic resin. The solvent adhesives are applied to both surfaces and the solvents allowed to evaporate before the parts are joined. Recommended epoxies are the anhydride-cured and amine-cured types. Also suitable is a two-component, polyamide-modified epoxy compound. Other adhesives that provide adequate bond strength to treated polyolefins include styrene-unsatmated polyester and solvent-type nitrile-phenolic (15). 

The data in Table 6.4 have been developed from many years of practical experience. It provides information on the suitable types of coupling agents differentiated by the organic portion of the molecule. In polymers which are not reactive, such as polyethylene, polypropylene, etc., adhesion is built up by hydrogen bond formation. Methaciylosilanes provide this effect with these materials. Experimental work is always recommended to evaluate each combination of coupling agent, substrate, and polymer. So many diverse factors are involved that theoretical predictions are not always reliable. 

Adhesives recommended include epoxies, polyurethane, silicone, nylon-epoxy, nitrile-phenolic, neoprene-phenolic, acrylic, cyanoacrylate, anaerobics, and partially hydrogenated polybutadiene (for bonding copper to polyethylene). 

Acceptable bonds have been obtained between polyethylene surfaces with polar adhesives such as epoxies (anhydride- and amine-cured and two-component modified epoxies) and solvent cements containing synthetic rubber or phenolic resin. Other adhesives recommended include styrene-unsaturated polyester and solvent-type nitrile-phenolic. 

The Scotch-Grip 880 elastomeric adhesive is recommended for bonding polysulfone to canvas, and Uralane 8615 for bonding polysulfone to polyethylene. 

Solvent cements are usually preferable to conventional adhesives for thermoplastic structural foams. Some solvent cements and solvent-containing, pressure-sensitive adhesives will collapse thermoplastic foams. Water-based adhesives based on SBR, polyvinyl acetate, or neoprene are frequently used. Solvent cementing is not effective on polyethylene foams because of their inertness. Recommendations for adhesives for thermoplastic foams are ... 

Phenylene oxide-based resins (Noryl ) epoxy, polyisocyanate, polyvinyl butyral, nitrile rubber, neoprene rubber, polyurethane rubber, polyvinyUdene chloride, and acrylic. Polyethylene-nitrile rubber, polyisobutylene rubber, flexible epoxy, nitrile-phenolic, and water-based (emulsion) adhesives. Polystyrene for these foams (expanded polystyrene (EPS)), aromatic solvent adhesives (e.g., toluol) can cause collapse of the foam cell walls. For this reason, it is advisable to use either 100% solids adhesives or water-based adhesives based on SBR or polyvinyl acetate. Specific adhesives recommended include urea-formaldehyde, epoxy, polyester-isocyanate, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, and reclaim rubber. Polystyrene foam can be bonded satisfactorily with any of the following general adhesive types ... 

Plasticisers are also used in products such as lacquers and adhesives that fall outside the definition of the plastics industry. Dicyclohexyl phthalate is used in nitrocellulose lacquers polyethylene glycol and its monostearate are compatible with cellulose nitrate. Dibutyl maleate is compatible with polyvinyl acetate, and di- -hexyl adipate, diethylene glycol di-2-ethyl butyrate or dibutyl sebacate can be used in polyvinyl butyral. Benzoates are recommended for... 

CN-704 is an acrylated polyester adhesion promoter that provides excellent adhesion to polyolefins, such as polyethylene and polypropylene. CN-704 is designed for UV/EB cured inks and coatings. Due to its low acid value, CN-704 can be used in foranilations containing tertiary amines. Usage levels of 40-60% are recommended. 

There was also an indication of severe adhesive fracture occurring during the extrusion process. When the extrusion was performed under lubricated condition or under dry conditions at high temperature, the surface was smooth. High density polyethylene could not be extruded satisfactorily under dry conditions at room temperature, but its extrusion at elevated temperature resulted in a smooth surface extrudate. Thus, from the point of view of surface finish, the extrusion of polymeric materials is recommended only under lubricated conditions or under dry conditions at elevated temperatures. 

These two-part acrylics do not require any pre-treatment of the joint surfaces or any surface primer and will bond polyethylene, polypropylene and ethylene copolymers with shear strengths in the range 4-8 N/mm. They can be used on many other substrates and so can be used as a general-purpose adhesive, although they are not recommended for bonding PTFE or the fluoropolymers. The resistance to water and high humidity environments is good but the mix ratio is critical to avoid unpredictable results. 

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