Polyisobutylene Products

5-2i Commercial Applications of Cationic Polymerization 5-2i-1 Polyisobutylene Products 

Butyl rubber (BR) is a copolymer of isobutylene with small amounts of isoprene produced by aluminum chloride initiated polymerization. About 1 billion pounds of butyl mbber are 

Fig 5-4 Slurry process for production of butyl rubber. After Kresge et al. [1987] (by permission of 

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Bedwick, BASF Oppanol s Polyisobutylenes, Product Information... 

The low molecular weight materials produced by this process are used as lubricants, whereas the high molecular weight materials, the polyisobutylenes, are used as VI improvers and thickeners. Polybutenes that are used as lubricating oils have viscosity indexes of 70—110, fair lubricating properties, and can be manufactured to have excellent dielectric properties. Above their decomposition temperature (ca 288°C) the products decompose completely to gaseous materials. 

Other Uses. Large quantities of hydrocarbon resins are used in mastics, caulks, and sealants (qv). Polymers for these adhesive products include neoprene, butyl mbber, polyisoprene, NR, SBR, polyisobutylene, acryHcs, polyesters, polyamides, amorphous polypropylene, and block copolymers. These adhesives may be solvent or water-borne and usually contain inorganic fillers. 

Polymerization. Polymerization reactions, which are addition reactions, are used to produce the principal products formed direcdy from butlylenes butyl elastomers polybutylenes and polyisobutylene (see Elastomers, synthetic Olefin polymers). 

Polyisobutylene and isobutylene—isoprene copolymers are considered to have no chronic hazard associated with exposure under normal industrial use. Some grades can be used in chewing-gum base, and are regulated by the PDA in 21 CPR 172.615. Vulcanized products prepared from butyl mbber or halogenated butyl mbber contain small amounts of toxic materials as a result of the particular vulcanization chemistry. Although many vulcanizates are inert, eg, zinc oxide cured chlorobutyl is used extensively in pharmaceutical stoppers, specific recommendations should be sought from suppHers. 

When X = Y, as in polyethylene, poly-(tetrafluoroethylene), polyisobutylene, and poly -(vinylidene chloride), the polymers are highly crystalline products with sharply definable melting points (except for polyisobutylene, which crystallizes readily on stretching but with difficulty on cooling). Oriented specimens of high strength may be obtained, exactly as in the crystalline condensation polymers. 

The inifer technique is a most convenient route for the preparation of well-defined end-reactive polyisobutylenes (PIB)(1). These materials may be linear or three-arm star telechelics carrying exactly 2.0 or 3.0 end-functions, respectively. The inifer technique yields tert.-chlorine-telechelic product, for example,... 

Figure 10 shows a spectrum of butyl rubber gum stock obtained on the solid at 80°C using normal pulsed FT techniques. Clearly it could be identified as a component in fabricated materials by direct nmr spectral analysis. Figure 11 shows spectra obtained from various portions of typical rubber products. These samples were cut from the rubber product, placed in an nmr tube without solvent, and spectra obtained at an elevated temperature. The data show how polyisoprene, a polyisoprene/polybutadiene blend and a polyisobutylene/polyisoprene/polybutadiene rubber blend are quickly identified in the materials. Figure 11a shows processing oil was present, and which was confirmed by solvent extraction. 

The type of products depends largely on the reaction temperature (Thomaset al., 81). At the boiling point of the isobutylene (— 6°) polymerization in the presence of boron fluoride yielded an oil after a considerable induction period. On the other hand, if the isobutylene was precooled to — 80° an immediate reaction occurred with almost explosive violence, producing a polymer of a very much higher molecular weight. The molecular weight of the polyisobutylene molecule increased from... 

Treatment of polyisobutylene (which contains terminal double bonds) with ozone followed by thermolysis produces polymeric radicals. Isobutylene-styrene block copolymer is formed when thermolysis is performed in the presence of styrene, but the process is not efficient because polystyrene and polyisobutylene homopolymers constitute more than half of the product [Cunliffe et al., 2001]. 

There has been an enormous technological interest in tertfa/j-butanol (tBA) dehydration during the past thirty years, first as a primary route to methyl te/f-butyl ether (MTBE) (1) and more recently for the production of isooctane and polyisobutylene (2). A number of commercializable processes have been developed for isobutylene manufacture (eq 1) in both the USA and Japan (3,4). These processes typically involve either vapor-phase tBA dehydration over a silica-alumina catalyst at 260-370°C, or liquid-phase processing utilizing either homogenous (sulfonic acid), or solid acid catalysis (e.g. acidic cationic resins). More recently, tBA dehydration has been examined using silica-supported heteropoly acids (5), montmorillonite clays (6), titanosilicates (7), as well as the use of compressed liquid water (8). 

P. Huber, BelgP 644290 (1964), claims polystyrene and/or polyisobutylene (3-5%) can be used as a gelling agent for inflammable hydrocarbons other org liquids, such as CS2. Depending on the intended use, the compositions can be made shock-resistant, adhesive, and/or productive of thick black smoke... 

The photo-cross-linkability of a polymer depends not only on its chemical structure, but also on its molecular weight and the ordering of the polymer segments. Vinyl polymers, such as PE, PP, polystyrene, polyacrylates, and PVC, predominantly cross-link, whereas vinylidene polymers (polyisobutylene, poly-2-methylstyrene, polymethacrylates, and poly vinylidene chloride) tend to degrade. Likewise, polymers formed from diene monomers and linear condensation products, such as polyesters and polyamides, cross-link easily, whereas cellulose and cellulose derivatives degrade easily. ... 

Isobutylene, like the other olefins already discussed, is a by-product of petroleum cracking and could be produced by the petroleum industry in large amounts by dehydrogenation of the corresponding paraffin. Since 1944 the principal outlet for isobutylene, excluding use in the manufacture of fuels, has been for direct polymerization to polyisobutylene and Butyl rubber (GR-I). 

C.E. Baxter, Jr., G. Valdez, C. Lobue, T. Lowry, and A. Abazajian, Midrange vinylidene content polyisobutylene polymer product produced by liquid phase polymerization process, US Patent 7 498396, assigned to Texas Petrochemicals LP (Houston, TX), March 3,2009. 

M.R. Grimbley and R.S. Lehrle, The degradation mechanism of polyisobutylene Part 2. characterisation of the products and the dependence of their yields on sample thickness provides detailed mechanistic information, Polym. Degrad. Stab., 48(3) 441-455,1995. 

Solution polymerization of refinery C4 streams in the presence of AICI3 or BF3 catalyst yields liquid polymers called polybutenes. Because of the large difference in stability of tertiary and secondary carbocations involved, isobutylene cannot be effectively copolymerized with butenes. As a result, the majority of the product formed is polyisobutylene. 

Fig. 1.4 gives such a plot, which was prepared by Philippoff (8,9) from his early measurements on a 15 per cent solution of polyisobutylene (P-100) in decalin (measurement temperatures 30 and 50°C). From this figure it is clearly seen that An as a function of p21 is non-linear. In contrast to the above mentioned solution of S 111 in methyl 4-bromo-phenyl carbinol, the solution of the poly-isobutylene P-100 in decalin does not form a second order fluid. However, for the product A n sin 2%, one obtains a beautiful straight line. The stress-optical law seems to hold also for this more general type of fluid. ... 

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