Polyethylene adhesives

EiaaHy, a new aluminum fire-resistant paneling consists of a composite design that iacludes a soHd thermoplastic compound core covered with a high density polyethylene adhesive film and an aluminum skin. The product is easily formable. It has sound deadening abiHties, and an optional poly(vinyHdene fluoride) resia coatiag provides damage resistance. 

Figure 4. Polyethylene adhesion of machine made papers at different critical surface tension levels. (Reproduced, with permission, from Ref. 4. Copyright 1966,...

TABLE III. POLYETHYLENE ADHESION OF SYNTHETIC SIZED PAPERS (from Fredholm and Westfelt, Reference 6)... 

In addition to the two fluorocarbon surfaces, it is informative to consider data for two hydrocarbon solid surfaces paraffin and polyethylene. Adhesion tension data for these surfaces have been presented by Fox and Zisman [35]. Selections of these data are given also in Table I, as are some additional data of Bascom and Singleterry for polyethylene [10]. 

For bonding two smooth glass surfaces, one might select a hot-melt polyethylene adhesive, an aqueous acrylic latex adhesive, or two-... 

Keywords Palm fibers, pineapple fibers, polypropylene, high-density polyethylene, adhesion, mechanical properties... 

Devine, A. T., and M. J. Bodnar, Effects of Various Surface Treatments on Adhesive Bonding of Polyethylene, Adhesives Age, May 1969. 

R. Walter, K. Friedrich, V. Privalko, A. Savadori (1997) On modulus and fracture toughness of rigid particulate filled high density polyethylene,/. Adhesion 64,87. 

Acryhc stmctural adhesives have been modified by elastomers in order to obtain a phase-separated, toughened system. A significant contribution in this technology has been made in which acryhc adhesives were modified by the addition of chlorosulfonated polyethylene to obtain a phase-separated stmctural adhesive (11). Such adhesives also contain methyl methacrylate, glacial methacrylic acid, and cross-linkers such as ethylene glycol dimethacrylate [97-90-5]. The polymerization initiation system, which includes cumene hydroperoxide, N,1S7-dimethyl- -toluidine, and saccharin, can be apphed to the adherend surface as a primer, or it can be formulated as the second part of a two-part adhesive. Modification of cyanoacrylates using elastomers has also been attempted copolymers of acrylonitrile, butadiene, and styrene ethylene copolymers with methylacrylate or copolymers of methacrylates with butadiene and styrene have been used. However, because of the extreme reactivity of the monomer, modification of cyanoacrylate adhesives is very difficult and material purity is essential in order to be able to modify the cyanoacrylate without causing premature reaction. 

In extmsion coating a polymer is extmded from a slot die into the nip of two roUs where it is bonded to a substrate under pressure (Fig. 6). A corona discharge may be appUed to the substrate just prior to the nip to enhance adhesion. Polyethylene or ionomer are the most common resins used in extmsion coatings. They provide improved moisture barrier (on paper), or sealabUity (on foU, polypropylene, or polyester). When a second substrate is introduced to the nip, laminated stmctures may be produced. 

An important newer use of fluorine is in the preparation of a polymer surface for adhesives (qv) or coatings (qv). In this apphcation the surfaces of a variety of polymers, eg, EPDM mbber, polyethylene—vinyl acetate foams, and mbber tine scrap, that are difficult or impossible to prepare by other methods are easily and quickly treated. Fluorine surface preparation, unlike wet-chemical surface treatment, does not generate large amounts of hazardous wastes and has been demonstrated to be much more effective than plasma or corona surface treatments. Figure 5 details the commercially available equipment for surface treating plastic components. Equipment to continuously treat fabrics, films, sheet foams, and other web materials is also available. 

Free mono- and multilayer films may be adhesive- or extmsion-bonded in the laminating process. The bonding adhesive may be water- or solvent-based. Alternatively, a temperature-dependent polymer-based adhesive without solvent may be heated and set by cooling. In extmsion lamination, a film of a thermoplastic such as polyethylene is extmded as a bond between the two flat materials, which are brought together between a chilled and backup roU. 

Lamination Inks. This class of ink is a specialized group. In addition to conforming to the constraints described for flexo and gravure inks, these inks must not interfere with the bond formed when two or more films, eg, polypropylene and polyethylene, are joined with the use of an adhesive in order to obtain a stmcture that provides resistance properties not found in a single film. Laminations are commonly used for food applications such as candy and food wrappers. Resins used to make this type of ink caimot, therefore, exhibit any tendency to retain solvent vapor after the print has dried. Residual solvent would contaminate the packaged product making the product unsalable. 

AppHcation of an adhesion-promoting paint before metal spraying improves the coating. Color-coded paints, which indicate compatibiHty with specific plastics, can be appHed at 20 times the rate of grit blasting, typically at 0.025-mm dry film thickness. The main test and control method is cross-hatch adhesion. Among the most common plastics coated with such paints are polycarbonate, poly(phenylene ether), polystyrene, ABS, poly(vinyl chloride), polyethylene, polyester, and polyetherimide. 

Attempts have been made to use cold-set adhesives in the cormgating operation, such as poly(vinyl acetate) and modified, precooked starch formulations, but these have not achieved any appreciable degree of commercial acceptance (20). The use of a polyethylene film appHed to the inside surface of the linerboard facing, which serves as a hot-melt cormgator adhesive, has achieved some commercial usage. However, its use is limited to the small, specialty product niche of fast-food hamburger cartons (see Olefin polymers, polyethylene). 

Sihcone products dominate the pressure-sensitive adhesive release paper market, but other materials such as Quilon (E.I. du Pont de Nemours Co., Inc.), a Werner-type chromium complex, stearato chromic chloride [12768-56-8] are also used. Various base papers are used, including polyethylene-coated kraft as well as polymer substrates such as polyethylene or polyester film. Sihcone coatings that cross-link to form a film and also bond to the cellulose are used in various forms, such as solvent and solventless dispersions and emulsions. Technical requirements for the coated papers include good release, no contamination of the adhesive being protected, no blocking in roUs, good solvent holdout with respect to adhesives appHed from solvent, and good thermal and dimensional stabiUty (see Silicon COMPOUNDS, silicones). 

CSPE. Chlorosulfonated polyethylene (CSPE), a synthetic mbber manufactured by DuPont, is marketed under the name Hypalon. It can be produced as a self-curing elastomer designed to cure on the roof. The membrane is typically reinforced with polyester and is available in finished thicknesses of 0.75 to 1.5 mm. Because CSPE exhibits thermoplastic characteristics before it cures, it offers heat-weldable seams. After exposure on the roof, the membrane cures offering the toughness and mechanical set of a thermoset. The normal shelf life of the membrane for maintaining this thermoplastic characteristic is approximately six months. After the membrane is fully cured in the field, conventional adhesives are needed to make repairs. 

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