Copolymer having low isoprenoid content

#This application is a US National Stage application under 35 USC 371 of PCT International Application No. PCT/CA2015/050353, filed on Apr. 28, 2015, which claimed the benefit of EP Patent Application No. 14174868.1 filed on Jun. 30, 2014, and EP Patent Application No. 14166578.6 filed on Apr. 30, 2014 the entire disclosures of each are hereby incorporated by reference in their entirety.

#Butyl rubber (IIR), a random copolymer of isobutylene and isoprene is well known for its excellent thermal stability, ozone resistance and desirable dampening characteristics. IIR is prepared commercially in a slurry process using methyl chloride as a diluent and a Friedel-Crafts catalyst as the polymerization initiator. The methyl chloride offers the advantage that AlCl3, a relatively inexpensive Friedel-Crafts catalyst, is soluble in it, as are the isobutylene and isoprene comonomers. Additionally, the butyl rubber polymer is insoluble in the methyl chloride and precipitates out of solution as fine particles. The polymerization is generally carried out at temperatures of about −90° C. to −100° C. (see U.S. Pat. No. 2,356,128 and Ullmanns Encyclopedia of Industrial Chemistry, volume A 23, 1993, pages 288-295, the entire contents of each of which are herein incorporated by reference). The low polymerization temperatures are required in order to achieve molecular weights which are sufficiently high for rubber applications.

#Recently there has been an emphasis on finding alternative diluents to the traditional chlorinated hydrocarbon, methyl chloride. Hydrofluorocarbons (HFC's) have similar properties to chlorinated hydrocarbons and are known refrigerants (see WO 2008/027518 and WO 2009/042847). Such HFC's, especially saturated HFC's, for example HFC-134a (1,1,1,2-tetrafluoroethane), have been identified as potential replacements for methyl chloride in polymerization processes involving higher temperatures (see U.S. Pat. No. 7,723,447, U.S. Pat. No. 7,582,715, U.S. Pat. No. 7,425,601, U.S. Pat. No. 7,423,100, U.S. Pat. No. 7,332,554, U.S. Pat. No. 7,232,872, U.S. Pat. No. 7,214,750, U.S. Pat. No. 7,699,962, US 2008/0290049, U.S. Pat. No. 7,781,547, U.S. Pat. No. 7,342,079, US 2007/0117939, US 2007/0299190, US 2007/0299161, US 2008/0234447, US 2008/0262180, U.S. Pat. No. 7,414,101, U.S. Pat. No. 7,402,636 and U.S. Pat. No. 7,557,170).

#In order that the invention may be more clearly understood, embodiments thereof will now be described in detail by way of example, with reference to the accompanying drawings, in which:

#FIG. 1A depicts reaction temperature profile for reactions with pure diluent components at −95° C.

#FIG. 1B depicts a graph showing molecular weight for polymers produced in various ratios of HFO-1234yf or HFC-134A with MeCl at −95° C.

#In this specification including the claims, the use of the article “a”, “an”, or “the” in reference to an item is not intended to exclude the possibility of including a plurality of the item in some embodiments. It will be apparent to one skilled in the art in at least some instances in this specification including the attached claims that it would be possible to include a plurality of the item in at least some embodiments.

#Butyl rubbers are formed by the copolymerization of at least one isoolefin monomer and at least one multiolefin monomer, and optionally further copolymerizable monomers.

#The present invention is not limited to a special isoolefin. However, isoolefins within the range of from 4 to 16 carbon atoms, preferably 4-7 carbon atoms, such as isobutene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 4-methyl-1-pentene and mixtures thereof are preferred. More preferred is isobutene.