Polyisobutylene, manufacture

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. 

Thermoplastics. There are five elastomeric membranes that are thermoplastic. Two materials, chlorinated polyethylene (CPE) and polyisobutylene (PIB), are relatively obscure. Thermoplastic materials can be either heat-fused or solvent-welded. In contrast to Hypalon and uncured EPDM, this abiHty to fuse the membranes together remains throughout the life of the material. However, cleaning of the membrane surface after exposure to weather is required. Correct cleaning procedures for specific membranes are available from the individual manufacturer. 

Polymers account for about 3—4% of the total butylene consumption and about 30% of nonfuels use. Homopolymerization of butylene isomers is relatively unimportant commercially. Only stereoregular poly(l-butene) [9003-29-6] and a small volume of polyisobutylene [25038-49-7] are produced in this manner. High molecular weight polyisobutylenes have found limited use because they cannot be vulcanized. To overcome this deficiency a butyl mbber copolymer of isobutylene with isoprene has been developed. Low molecular weight viscous Hquid polymers of isobutylene are not manufactured because of the high price of purified isobutylene. Copolymerization from relatively inexpensive refinery butane—butylene fractions containing all the butylene isomers yields a range of viscous polymers that satisfy most commercial needs (see Olefin polymers Elastomers, synthetic-butylrubber). 

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 polyisobutylene-based adhesive is that the protective... 

Forms of BR and polyisobutylene. The properties of butyl rubber and polyisobutylene depend on their moleeular weight, degree of unsaturation, nature of the stabilizer incorporated during manufacture and, in some cases, chemical modification. It is common to produce halogenated forms of butyl rubber to increase polarity and to provide a reactive site for alternate cure mechanisms [6],... 

Refs 1) Beil — not found la) S. Lemer, Development of a Semiplant Process to Manufacture Composition C-4 (Harrisite) , PATR 2292 (1956) 2) Anon, Polyisobutylene... 

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). 

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). 

The abovementioned materials can be mixed with one another. A series of other polymers and resins can also be added if the substances listed in 1 to 4 form the bulk of the material. Additional materials are PE, PP, low molecular weight polyolefins, polyterpenes (mixtures of aliphatic and cycloaliphatic hydrocarbons produced by polymerisation of terpene hydrocarbons), polyisobutylene, butyl rubber, dammar gum, glycerine and pentaerythritol esters of rosin acid and their hydration products, polyolefin resins, hydrated polycyclopentadiene resin (substance mixtures manufactured by thermal polymerization of a mixture mainly composed of di-cyclopentadiene with methylcyclopentadiene, isoprene and piperylene which is then hydrogenated). 

Occasionally, low molecular weight polymers are required as sealants, adhesives, or in rocket solid propellants. F. P. Baldwin and co-workers report on the manufacture of a low molecular weight carboxy terminated product made by depropagating ozonization of a higher molecular weight polyisobutylene. 

Some alkene monomers can be polymerized by a cationic initiator, as well as by a radical initiator. Cationic polymerization occurs by a chain-reaction pathway and requires the use of a strong protic or Lewis acid catalyst. The chain-carrying step is the electrophilic addition of a carbocation intermediate to the carbon-carbon double bond of another monomer unit. Not surprisingly, cationic polymerization is most effective when a stable, tertiary carbocation intermediate is involved. Thus, the most common commercial use of cationic polymerization is for the preparation of polyisobutylene by treatment of isobutylene (2-mcthylpropene) with BF3 catalyst at -80 C. The product is used in the manufacture of inner tubes for truck and bicycle tires. 

Lower molecular weight polyisobutylene is sold by BASF as Glissopal , as an important intermediate for the manufacture of additives for fuels and lubricants, made in plants in Antwerp and Ludwigshafen of capacities 100,000 and... 

Surface lubricants used in the manufacture of metallic articles acetyl tributyl citrate, acetyl tiiethyl citrate, butyl stearate, castor oil, dibutyl sebacate, di-(2-ethylhexyl) azelate, di-(2-ethylhexyl) sebacate, diisodecyl phthalate, di-(2-ethyl-hexyl) phthalate, diethyl phthalate, di-n-octyl sebacate, epoxidi soybean oil, polyisobutylene (minimum molecular weight 300),... 

Low-density polyethylene (LDPE) was blended with polyisobutylene, 25 0 wt% (PIB), and a copolymer of styrene and isobutylene, 0-10 wt% (PSIB), for the use as transparent, impermeable, shrink-wrap packaging films. In the Phillips patent, LLDPE was blended with PIB to manufacture grocery bags. In the BASF patent, a pre-blend comprising 60 wt% PIB and LDPE was granulated and subsequently compounded with LDPE... 

Manufacture and compounding The majority of organic solvent-based adhesives are based on rubbery polymers, the main ones being natural rubber, polychloroprene, butadiene-acrylonitrile, styrene-butadiene and polyisobutylene. Traditionally, the rubber was placed in a heavy-duty mixer and solvent was added slowly till a smooth solution was formed. In some cases, the rubber was milled beforehand to reduce viscosity and produce smoother solutions. Nowadays, it is possible to obtain some grades of material that only require stirring in a comparatively simple chums. 

Polyisobutylenes prepared this way ( = about 50) are used as additives in lubricating oil and as adhesives in pressure-sensitive tape and removable paper labels. Higher-molecular-weight polymers are used in the manufacture of inner tubes for truck and bicycle tires. 

Polyolefins, Polyethylenes, Polyisobutylenes, Poly(Methyl Methacrylates), and Poly(Styrene Sulfonates), In addition to polyurethane foams, polyethylene and polypropylene fibers can be manufactured as alternative polymeric sorbents. However, based on sorbent capacity, cost, and availability, these materials would be considered inferior to polyurethane. 

Polyolefins, PO. First impact modification of PO, by addition of elastomers, was patented independently by Bayer A.-G. and Standard Oil Co. in 1937. The isotactic polypropylene, PP, was commercialized in 1957, and its first blends (with polyisobutylene, PIB, and polyethylene, PE) were patented in 1958. In 1960, du Pont started manufacturing ethylene-propylene, EPR, and three years later ethylene-propylene-diene, EPDM, copolymers [Gresham and Hunt, I960]. The first patent on impact modification of PP by addition of EPR dates from 1960. Direct reactor blending of PE/PP/EPR resulting in a thermoplastic polyolefin, R-TPO, dates from 1979. The newest (introduced in 1992) single-site metallocene catalysts generate polymers with controlled tacticity, co-monomer sequences, molecular... 

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