Butyl rubber solvent-based adhesives

Use of Solvent-based adhesives in seaming stems from the pioneering work of Charles Macintosh in the last century seam bonding with rubber solutions was a method used in the original waterproof coats carrying his name. Developments of the rubber-bonded seams are used in the manufacture of items such as life jackets and life rafts. The following (in cross-linked form) are commonly used Natural rubber-based adhesives, Poiychioroprene rubber adhesives, Poiyurethane and butyl rubber. 

Butyl rubbers can be bonded with most engineering adhesives and cyanoacrylates show high strength with the substrate failing before the adhesive bond (Table 4.1). Some solvent-based adhesives show good strength on butyl rubber, especially if the rubber is cleaned with a chlorinated solvent prior to bonding. 

Polyurethane epoxy, polyester, polyacrylate, polyhydroxyether, nitrile rubber, butyl rubber, water-based (emulsion), polyurethane rubber, neoprene, SBR, melamine-formaldehyde, and resorcinol-formaldehyde are specific types. Generally, a flexible adhesive should be used for flexible polyurethane foams. Synthetic elastomer adhesives with fast-tack characteristics are available in spray cans. Solvent-based neoprenes are recommended for resistance to stress, water, and weathering. Solvent-based nitriles are recommended for resistance to heat, solvents, and oil. Water-based adhesives... 

Early adhesive uses of butyl rubber generally consisted of solvent-based dispersions, or tape and rope extrusion of formulated solid rubber. Extensive use was made of butyl rubber s inherent tackiness in highly saturated grades of the polymer to make pressure sensitive tapes and precoated films. The polymers are also extensively used as major components of hot-melt adhesives, solid rubber sealing tapes, and caulking grades of sealants and mastics, of which most were high solids content solvent-based formulations. 

In the hot-melt type, two principal polymer types are used polyolefin and ethylene co-polymer based and polyester and polyamide type. In the solvent-based type, the most prominent are neoprene (polychloroprene)-based solvent and latex types, and polyvinyl acetate emulsions. For pressure-sensitive adhesives, the most favored are acrylic adhesives and butyl rubber/polyisobutylene types. 

Butyl rubber is an elastomeric polymer used widely in adhesives and sealants, both as primary binders and as tackifiers and modifiers. Butyl rubber is a copolymer of isobutylene with a small amount of isoprene. These materials have relatively low strength and tend to exhibit creep under load. They are useful in packaging apphcations where their low permeability to gases, vapors, and moisture can be exploited. Butyl rubber is also used as an adhesive sealant. It is generally applied from a solvent-based solution. Table 5.1 summarizes some of the important properties of butyl rubber adhesives. 

Plastic foams. Some solvent cements and solvent-containing pressure-sensitive adhesives will collapse thermoplastic foams. Water-based adhesives, based on styrene butadiene rubber (SBR) or polyvinyl acetate, and 100 percent solid adhesives are often used. Butyl, nitrile, and polyurethane adhesives are often used for flexible polyurethane foam. Epoxy adhesives offer excellent properties on rigid polyurethane foam. 

Plasticizers are used in butyl rubber, polyureAane, polysulfide, solvent aerylies, polyvinyl acetate, and silicone rubber adhesives and sealants. The compatibility of the plasticizer depends on base polymer chemistry. Plastieizers for silicone systems are low molecular weight... 

Solvents (A.S.C., 1986 Dick, 1987) - Solvents are used in evaporation type adhesives and sealants. They act as the carrier in which the base polymer is dissolved to provide low viscosity solutions that can accommodate fillers and otheradditives. Butyl rubber solutions are made with 50 to 70% rubber and 30 to 50% solvent. These are the bases of products which vary from unfilled viscous liquids to semi-solid filled sealants. Solvent release sealants generally range from 70 to 80% total solids. The solvent level is chosen so that adhesive or sealant is easy to apply and wets the adherend surface. After application, the solvent evaporates from the glue-line leaving the polymer bonded to the adherend. 

Butyl phenolic resin is a typical tackifier for solvent-borne polychloroprene adhesives. For these adhesives, rosin esters and coumarone-indene resins can also be used. For nitrile rubber adhesives, hydrogenated rosins and coumarone-indene resins can be used. For particular applications of both polychloroprene and nitrile rubber adhesives, chlorinated rubber can be added. Styrene-butadiene rubber adhesives use rosins, coumarone-indene, pinene-based resins and other aromatic resins. 

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