Patent GB-701453-A (GB)
Title: Improvements in or relating to brominated isoolefin-polyolefin interpolymer and method of preparing same
IPC: C08L23/28
Filed: 1951-04-12
Abstract: Brominated iso-olefin-polyolefin interpolymers are prepared by after-bromination or by interpolymerizing an iso-olefinic with a polyolefinic monomer, at least one of which is brominated so as to contain a <FORM:0701453/IV (a)/1> structure.  The former method is preferred and the interpolymers are those containing a major proportion, e.g. 70-99 per cent., of an iso-olefin such as isobutylene, 3-methyl-butene-1, 4-methyl-pentene-1, 2-ethyl-butene-1, or 4-ethyl-pentene-1, with a proportion, e.g. 1-30 per cent., of a polyolefin such as: (1) acyclic conjugated dienes, e.g. butadiene, isoprene, 2, 4-dimethyl butadiene, piperylene, 3-methyl butadiene, hexadiene-2, 4 and 2-neopentyl butadiene; (2) acyclic non-conjugated diolefins, e.g. dimethallyl and its homologues, 2-methyl hexadiene-1, 5, 2-methyl pentadiene-1, 4 and 2-methyl heptadiene-1, 6 and -1, 4; (3) alicyclic diolefins, e.g. cyclopentadiene, cyclohexadiene, 1-vinyl cyclohexene-3 and -1, 1-vinyl cyclopentene-1, 1-vinyl cyclobutene-2 and dicyclopentadiene, and terpenes such as dipentene, terpinenes, terpinolene, phellandrene and sylvestrene; (4) triolefins, e.g. 2, 6-dimethyl-4-methylene-heptadiene-2, 5, 2-methylhexatriene-1, 3, 5, myrcene, ocimene, allo ocimene, fulvene and substituted fulvenes, 1, 3, 3-trimethyl-6-vinyl cyclohexadiene-2, 4 and cyclo-heptatriene; (5) higher polyolefins, e.g. 6, 6-vinyl methyl fulvene and 6, 6-diisopropenyl fulvene. The interpolymer may contain a third constituent such as styrene, chlorostyrenes, acrylyl chloride and methallyl chloride. Reclaimed interpolymers may also be used.  The brominating agent may be bromine itself or sodium hypobromite, magnesium bromide hexahydrate, N-bromosuccinimide, alpha - bromo - aceto - acetanilide, beta-bromoethyl phthalimide, N-bromoacetamide, tribromo phenol bromide, bromo-beta naphthol and pyridinium bromide perbromide.  The reaction may be carried out by making a solution, dispersion or cement of the copolymer in a solvent or diluent, e.g. toluene, chlorobenzene, hexane, heptane, trichloroethane or carbon tetrachloride, and adding the brominating agent as such or in solution, e.g. in carbon tetrachloride.  The resulting solution or dispersion may be used as such, e.g. as an adhesive, or the brominated product may be precipitated by adding a non-solvent such as alcohol or water. The solvent or diluent in the reaction may be a low boiling liquid, e.g. methyl or ethyl chloride or butane, and the reaction carried out in the liquid phase, the product being isolated by flashing off the solvent.  This process may be integrated with the low temperature polymerization of the iso-olefin and polyolefin. The bromination may also be effected by passing gaseous bromine over the finely-divided copolymer.  Also a solid brominating agent may be mixed with the solid copolymer and heated to liberate bromine.  Excess bromine is neutralized with sodium carbonate, after which finely divided calcium silicate is added.  The percentage of combined bromine in the copolymers may be from 0.5 upwards, preferably from 1 to 6 per cent.  In the alternate method of obtaining the bromine-containing copolymers by using a bromine-containing monomer, 2, 3-dibromobutadiene is specified as co-monomer with isobutylene.  The products may be used as adhesives to bond rubbery materials together, are easily vulcanized alone, with or without sulphur, or in admixture with natural or synthetic rubber, and may be made into inner-tubes, tyres and other articles.  The synthetic rubbers which may be mixed in bulk, solution or dispersion, with the brominated copolymers include polymers and copolymers of diolefinic compounds, many of which are listed.  Specified compounding ingredients are zinc oxide, sulphur, stearic acid, 2-mercaptobenzothiazole, diphenyl guanidine, tetramethyl thiuram disulphide, titanium dioxide and ultramarine blue.ALSO:Rubber is mixed with bromine-containing copolymers of an iso-olefin and a polyolefin to yield mixtures which may be vulcanised to give products of improved resistance to ozone, flex and air-diffusion.  The bromine-containing copolymers, themselves, may also be used as adhesives for bonding rubbery materials to each other, especially the unbrominated iso-olefin-polyolefin copolymers to each other, to natural rubber and to diene synthetic rubbers.  The bromine-containing copolymers are preferably obtained by after-bromination but they may be prepared from an isoolefinic and a diolefinic compound at least one of which contains bromine in the group <FORM:0701453/V/1> , e.g. 2, 3-dibromobutadiene.  The preferred copolymers to be brominated are those known as Butyl rubber but a long list of iso-olefins and polyolefins is given (see Group IV(a)). The compositions containing rubber are milled with usual compounding ingredients and may be vulcanized with sulphur or with a divalent metal oxide, e.g. zinc oxide.  The vulcanisates are especially useful in the manufacture of inner tubes.  For use as adhesives, the brominated copolymers are disolved in a solvent, e.g. that in which bromination was effected, e.g. n-heptane and applied to the sheets of natural or synthetic rubber.