Butyl rubber manufacture

Butyl mbber, a copolymer of isobutjiene with 0.5—2.5% isoprene to make vulcanization possible, is the most important commercial polymer made by cationic polymerization (see Elastomers, synthetic-butyl rubber). The polymerization is initiated by water in conjunction with AlCl and carried out at low temperature (—90 to —100° C) to prevent chain transfer that limits the molecular weight (1). Another important commercial appHcation of cationic polymerization is the manufacture of polybutenes, low molecular weight copolymers of isobutylene and a smaller amount of other butenes (1) used in adhesives, sealants, lubricants, viscosity improvers, etc. 

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],... 

Chemical and Other Specialty Manufacture A wide variety of products may be derived from petroleum feed stocks, including such diverse materials as alcohols, butyl rubber, sulfur, additives, and resins. Other specialties such as solvent naphthas, white oils, Isopars, Varsol, may also be produced. As indicated previously the respective chemical affiliate usually has responsibility for products broadly classified as petrochemicals. 

Isoprene (2-methyl 1,3-butadiene) is the second most important conjugated diolefin after butadiene. Most isoprene production is used for the manufacture of cis-polyisoprene, which has a similar structure to natural rubber. It is also used as a copolymer in butyl rubber formulations. 

Butyl rubber - This material generally had the least endurance in fatigue tests, but it may be adequate for some cardiovascular applications. Advantages include less sensitivity to stress concentrators than Pellethane, a very low permeability to fluids, a moderate creep resistance and widespread availability at low cost. Disadvantages include a relatively low fatigue resistance compared to the elastomers specifically designed for these applications. The rubber tested was not designed for medical applications and had standard rubber additives and modifiers that were cytotoxic unless the material was extracted after manufacture. 

Brominated butyl rubber, 4 436 development of, 4 434 manufacture, 4 400, 442—444 Brominated carbonate oligomers,... 

Chlorinated additive flame retardants, 11 468-470, 471-473t Chlorinated aromatics, 6 242 decomposition using microwaves, 16 555 Chlorinated butyl rubber, 4 436 development of, 4 434 manufacture, 4 400, 442-444 Chlorinated ethanes... 

Star-branched butyl rubber, 4 437-438 copolymers, 4 445-446 Starch(es), 4 703-704, 20 452-453 as blood substitute, 4 111-112 cationic, 18 114-115 in cereal grains, 26 271-274 in cocoa shell from roasted beans, 6 357t compression effects in centrifuges, 5 513 depolymerization, 4 712 in ethanol fermentation, 10 534—535 etherified, 20 563 as a flocculant, 11 627 high-amylose, 26 288 Mark-Houwink parameters for, 20 558t modified and unmodified, 12 52-53 in paper manufacture, 18 122-123 performance criteria in cosmetic use, 7 860t... 

Uses Coolant and refrigerant herbicide and fumigant organic synthesis-methylating agent manufacturing of silicone polymers, pharmaceuticals, tetramethyl lead, synthetic rubber, methyl cellulose, agricultural chemicals and nonflammable films preparation of methylene chloride, carbon tetrachloride, chloroform low temperature solvent and extractant catalytic carrier for butyl rubber polymerization topical anesthetic fluid for thermometric and thermostatic equipment. 

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 use pattern for methyl chloride in the United States in 1992 and 1995 was (%) methyl chlorosilanes used as intermediates for silicones, 80 methyl cellulose manufacture, 6 quaternary ammonium compounds, 5 agricultural chemicals, 5 butyl rubber production, 2 and miscellaneous, 2 (Anon., 1992, 1995). 

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 liquid 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-BUTYL rubber). 

RUBBER (Synthetic). Any of a group of manufactured elastomers that approximate one or more of the properties of natural rubber. Some of these aie sodium polysulfide ( Thiokol ). polychloiopiene (neoprene), butadiene-styrene copolymers (SBR), acrylonitrilebutadiene copolymers (nitril rubber), ethvlenepropylene-diene (EPDM) rubbers, synthetic poly-isoprene ( Coral, Natsyn ), butyl rubber (copolymer of isobutylene and isoprene), polyacrylonitrile ( Hycar ). silicone (polysiloranei. epichlorohy-drin, polyurethane ( Vulkollan ). 

Propane is a good solvent for other hydrocarbons and the plasticizers4 used in elastomers. It is important that the right fuel hoses be used for propane. Hoses made from butyl rubber are not compatible with propane and will swell and leak. Hoses made from nitrile or neoprene should be used and are compatible with LP gas. However, even in hoses made from compatible materials, residues may result from these hoses primarily from two sources grease inside the hose from manufacturing and plasticizers present in the hose that are leached out by the propane upon first contact. (The extent of leach-out can be a function of the... 

The chloride is used to manufacture silicones, tetramethyl lead and triptane (2,2,3 trimethylbutane). Lesser uses include the manufacture of butyl rubber, higher halogenated methanes, methyl cellulose, quaternary ammonium compounds, methyl mercaptan, methionine, fungicides and pesticides (primarily the Me-arsenate herbicides). Recently the chlorinated fluorocarbons have replaced CH3CI as high volume refrigerants and propellants (ref. 32) Tables 12 and 13 list the chemical and physical properties and potential numbers of workers exposed to the monohalomethanes. 

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). 

Methyl chloride is the only chlorinated methane with good growth. The principal use for methyl chloride is in the manufacture of chlorosilanes (89%) for the silicone industry. Other smaller uses are for methyl cellulose ether, quaternary ammonium compounds, herbicides, and butyl rubber. 

Isobutene is used in the field of elastomers, mainly to manufacture a special rubber, butyl rubber, by copolymerization with small amounts of isopiene. It serves essentially for the manufacture of inner tubes, but its production remains modest and accounts for barely 10 per cent of that of SBR (Styrene Butadiene Rubber). Isobutene is also used to produce additives for oils (polyisobutenes), detergents (di- and triisobutylenes) and cur rently for the manufacture of MTBE. 

Large-scale manufacture of butyl rubber started during World War II, in the scope of the U.S. Government rubber-procurement program, and the actual process is essentially similar to the historical one [9]. Bromi-nated butyl (BIIR) was introduced in the 1950s by Goodrich Chemical Co. [54-56] but substantial commercial development occurred only in 1971 when the Polysar Ltd continuous and economic manufacturing process based on elemental bromine came onstream [57]. Production of chlorinated butyl (CIIR) was introduced on a commercial scale by Exxon Chemical in 1961. 

The isoprene unit is the most important building block for lipids, steroids, terpenoids, and a wide variety of natural products. The only chemical reaction of commercial importance (other than polymerization) is its conversion to terpenes. Isoprene is used in the manufacture of synthetic natural rubber, butyl rubber, and as a copolymer in the production of synthetic elastomers. 

Red phosphorus (RP) is a component of matchbox strike plates and is used as an ingredient in certain commercial rat and cockroach poisons. RP is used in the manufacture of pyrotechnics, semiconductors, fertilizers, incendiary shells, smoke bombs (in combination with butyl rubber), and tracer bullets. It is also used in organic synthesis reactions and in the manufacture of phosphoric acid, phosphine, phosphoric anhydride, phosphorus pentachloride, phosphorus trichloride, and in electroluminescent coatings. RP (2-10%) is also used as a flame-retardant additive for plastics such as polyamides. 

Examples of preservatives are phenylmercuric nitrate or acetate (0.002% w/v), chlorhexidine acetate (0.01% w/v), thiomersal (0.01% w/v) and benzalkonium chloride (0.01% w/v). Chlorocresol is too toxic to the corneal epithelium, but 8-hydroxy-quinoline and thiomersal may be used in specific instances. The principal consideration in relation to antimicrobial properties is the activity of the bactericide against Pseudomonas aeruginosa, a major source of serious nosocomial eye infections. Although benzalkonium chloride is probably the most active of the recommended preservatives, it cannot always be used because of its incompatibility with many compounds commonly used to treat eye diseases, nor should it be used to preserve eye-drops containing anaesthetics. As benzalkonium chloride reacts with natural rubbers, silicone or butyl rubber teats should be substituted and products should not be stored for more than 3 months after manufacture because silicone rubber is permeable to water vapour. As with all rubber components, the rubber teat should be pre-equilibrated with the preservative before use. Thermostable eye-drops and lotions are sterilized at 121 °C for 15 minutes. For thermolabile drugs, filtration sterilization followed by aseptic filling into sterile containers is necessary. Eye-drops in plastic bottles are prepared aseptically. 

Use Monomer for manufacture of polyisoprene, chemical intermediate, component of butyl rubber. 

Typical spectral peaks to aid in the identification of coating elastomers and rubbers are shown in Tables 7.4 and 7.5 (Verleye et al., 2001). The tables show that the infrared spectroscopic technique is invaluable in detecting characteristic peaks to identify the differences between chemically similar hydrocarbon polymers, such as polyolefins, natural and butyl rubbers. It is also sensitive enough to show the difference between polyester and polyether urethanes. Modem FUR machines can store, retrieve and compare spectra to enable manufacturers to check quality, identity and characteristics of the polymer materials they use (RAPRA, 2004). 

The most important of the commercial cationic copolymers is butyl rubber prepared from isobutylene and isoprene. Because of its very low air permeability, butyl rubber finds extensive use in tire inner tubes and protective clothing. It is manufactured by low-temperature (— 100°C) copolymerization of about 97% isobutylene and 3% isoprene in chlorocarbon solvents with AICI3 coinitiator (see Table 8.5). More recently, an ozone-resistant copolymer of isobutylene and cyclopentadiene has been marketed. 

The S6 was replaced by the S10 in 1986, to meet the changing requirements of new weapon and communications systems, and improved serviceability and reduced manufacturing costs. The S10 profited from the availability of new polymer materials, and had a butyl rubber facepiece with a reflex faceseal and eyepieces with improved compatibility with optical systems. 

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