Adhesives, poly isobutylene

Fig. 32 Stress-strain curves for poly(isobutene) (PIBUT), poly(isobutylene) (PIB85000), and a model acrylic adhesive during adhesive testing on a silicone-coated surface. Adopted with permission from [173]. Copyright 2010 John Wiley Sons, Inc.

Poly(isobutylene) only crystallizes under stress. Because of the low glass transition temperature (-70 C), its lack of crystallinity, and the somewhat weak intermolecular forces, poly (isobutylene) is an elastomer. The low-molar-mass material is used as an adhesive or viscosity improver. The higher-molar-mass products are employed as rubber additives or for very airtight tubes. The cold flow (creep) can be diminished or eliminated by the addition of polyethylene. Poly(isobutylenes) modified by copolymerization are used as protective sheeting for building sites and as anticorrosive coverings (e.g., a copolymer of 90% isobutylene and 10% styrene). 

One of the shorter-term applications is the use of protective films on vehicles for shipment from the manufacturer to the dealers. These protective films are typically polyolefins coated with a removable adhesive for easy application and removal without leaving hard to clean adhesive residue on the vehicle. Several adhesives have been reported for this type of application, including the less common polyisobutylene-based PSAs [139]. A possible advantage of combining a polyolefin backing with a poly isobutylene-based adhesive is that the protective... 

In laminating or coating, a preformed solid film of plastic is bonded with glue or adhesive directly onto the material to be laminated. Composite films of cellulose and poly(ethylene), for example, are produced in this way. In these composite films, the cellulose protects from foreign odors and the poly(ethylene) assures water-tightness. Composite films of poly(isobutylene) and poly(ethylene) are used in the construction of chemical apparatus made of steel. Poly(ethylene) takes care of the protection against corrosion, and poly(isobutylene), with adhesives, the adhesion to steel. Steel sheet laminated with PVC can be processed as normal, but is noncorrosive in the absence of any further treatment. Metal aircraft parts are often coated with films of poly(tetrafluoroethylene). Poly(tetrafluoroethylene) is difficult to wet, and this decreases the tendency to ice over. 

Properties and Applications. Poly(isobutylene) only crystallizes under stress. Because of the low glass-transition temperature (—70°C), its lack of crystallinity, and the somewhat weak intermolecular forces, poly(isobutylene) is an elastomer. The low-molecular-weight material is used as an adhesive... 

Natural rubber and poly (Isobutylene) First-aid dressings Adherence during normal daily activity, quick adhesion... 

Poly isobutylene, PIB. Applications adhesives, sealing compounds, electrical insulating oils, viscosity improvers. 

ToF-SIMS, and also in some cases XPS, has been applied to a range of polymer problems such as adhesion studies of elastomers based on brominated poly(isobutylene-co-4-methylstyrene) and diene elastomers [229], PVC [230], epoxy resin aluminium [231,232], glass rubber [233], squalene brass [234], and sealants [235]. 

Butyl rubber and polyisobutylene are elastomeric polymers used quite widely in adhesives and sealants both as primary elastomeric binders and as tackifiers and modifiers. The principal difference between these polymers is that butyl is a copolymer of isobutylene with a minor amount of isoprene, which introduces unsaturation, while poly isobutylene is a homopolymer. 

The inherent properties of polymers of the poly isobutylene family, particularly the chemical inertness, age and heat resistance, long-lasting tack, flexibility at low temperatures, and the favorable FDA position on selected grades, make these products commercially attractive in a variety of pressure-sensitive and other adhesives, in automotive and architectural sealants, and in coatings. An added dimension is achieved in the blendability of the polyisobutylene polymers with each other and with other adhesive polymers such as natural rubber, styrene-butadiene rubber, EVA, low molecular weight polyethylene, and amorphous polypropylene to achieve specific properties. They can, for example, be blended with the highly unsaturated elastomers to enhance age and chemical resistance. A description of poly isobutylene polymer family use in adhesive and sealant applications follows. 

Two important parameters in the formulation of pressure sensitive adhesives are tack and hold, which is the ability to resist creep under deadload. As noted, butyl and polyisobutylene are inherently tacky polymers. This tack can be enhanced with a wide variety of resins and other tackifiers. The hold or cohesive strength is low compared to some other pressure sensitive adhesive polymers, such as natural rubber, but can be increased if required by (1) incorporation of high molecular weight PIB or natural rubber, (2) the choice of the other ingredients, particularly resins and fillers, and (3) the partial or preferential curing techniques noted previously. The poly isobutylene polymers are primarily used in label pressure sensitive adhesives and in certain tapes where high cohesive strength is not necessary. 

Exxon Chemical Co., Escorez Resins and Vistanex LM Poly isobutylene in Low Temperature Pressure Sensitive Adhesives, Bulletin R 79-54, Houston, 1979. 

Butyl rubber is an elastomeric polymer used widely in adhesives and sealants, both as primary binders and as tackifiers and modifiers. Butyl rubber is poly(methylpropene-co-2-methyl-1,3-butadiene) or poly(isobutylene-co-isoprene). The latter is a copolymer of isobutylene with a small amount of isoprene [28]. These materials have relatively low strength and tend to exhibit creep under load. They are useful in packaging applications 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 [3,7]. Table 5.7 summarizes some of the important properties of butyl rubber adhesives. 

Polyisobutylene and butyl mbber are two materials that are based upon the polymer made from the polymerization of isobutylene. Poly(isobutylene) is not reactive after manufacture and hence it has been used as a modifier for various types of adhesives and sealants. Butyl mbber is made by the addition of isoprene to the polymerization of isobutylene. This addition yields a small amount of unsaturation in the polymer, thus making this material crosslinkable. In addition, chlorinated and brominated versions of this material are also available. Poly(isobutylene)s have a low glass transition temperature of -60 °C and are therefore expected to have flexibility at low temperature. Because of their stmaure, poly (isobutylene) and butyl mbber are expected to have high impermeability to air and moisture transfer, making these materials ideal for sealant formulation. Poly(isobutylene) is manufactured in a wide range of molecular weights, ranging from 45 000 to 2110 000. 

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