Chlorine-free, non-drying isobutene/diene copolymers and process

Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...

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526212, 526237, 526336, 526308, 526290, 585508, 585525, 585507, C08F 414, C08F21012

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055569323

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BRIEF SUMMARY
The present invention relates to chlorine-free, non-drying copolymers of isobutene with C.sub.4 -C.sub.10 -dienes having isolated or conjugated double bonds, containing at least 60 mol % of terminal double bonds and having a molecular weight M.sub.n of from 500 to 5,000 Dalton, and a process for their preparation.
Copolymers of dienes and isobutene are used for the preparation of fuel and lubricating oil additives, as described in GB-A 2 231 873. A molecular weight of these copolymers of from 500 to 5,000 Dalton and in particular a high content of terminal double bonds of more than 50, preferably more than 60, mol % are essential for ensuring that diene/isobutene copolymers can be used economically for the stated purpose. The terminal double bonds are required in order to permit the copolymer to be converted by reaction with, for example, maleic anhydride into the maleic acid/copolymer adduct, which is then reacted with amines to give fuel and lubricating oil additives according to GB-A 2 231 873.
Although copolymers of, for example, 1,3-butadiene or isoprene with isobutene are mentioned in GB-A 2 231 873 as starting materials for the preparation of the relevant additives, diene/isobutene copolymers have to date been unimportant for this purpose since it has not been possible so far to prepare diene/isobutene copolymers meeting the stated requirements with respect to the molecular weight and the content of terminal double bonds.
A survey of the preparation of isobutene/diene copolymers is given in H. G uterbock, Polyisobutylen und Isobutylen-Mischpolymerisate, pages 122 to 127, Springer Berlin 1958.
U.S. Pat. No. 2,818,460 describes the preparation of drying oils by the copolymerization of isobutene with 1,3-butadiene, anhydrous hydrogen fluoride in an N,N-dialkylamide solvent being used as a catalyst. U.S. Pat No. 2 780 664 likewise relates to the preparation of drying oils by copolymerization of 1,3-butadiene with isobutene, boron trifluoride etherares in an alkyl halide solvent being used as catalysts. If a 1:1 boron trifluoride/methanol complex is used as the catalyst, gel-like or resinous copolymers are formed.
Only highly polymeric isobutene/butadiene or isoprene copolymers, referred to generally as butyl rubber, have become industrially important to date and are prepared with the aid of aluminum chloride as the catalyst. However, in the presence of the aluminum chloride catalyst and in the presence of halogenated, in particular chlorinated, solvents, halogenated copolymers may be formed. The formation of high molecular weight isobutene/diene copolymers as well as the formation of halogenated isobutene/diene copolymers are however undesirable when said copolymers are used for the preparation of fuel additives, on the one hand owing to the low solubility of the high molecular weight copolymers and on the other hand halogenated dioxin derivatives may be released with the exhaust gas in the combustion of halogen-containing fuel additives, the formation and release of which derivatives are to be avoided for ecological and toxicological reasons.
In U.S. Pat. No. 2 578 214, non-drying oils are produced by copolymerization of isobutene with 1,3-butadiene, aluminum chloride being used as the catalyst. Boron trifluoride is likewise proposed as a catalyst. In this process, however, the major part of the terminal double bond is isomerized to internal double bonds owing to the very reactive catalysts used therein, so that the copolymer obtained by this process is likewise unsuitable as a starting material for the preparation of the stated fuel additives.
The difficulties in the preparation of isobutene/diene copolymers having a high content of terminal double bonds, also referred to herein as highly reactive isobutene/diene copolymers, are essentially due to the fact that the Lewis or Br enstedt acid polymerization catalyst itself catalyses the isomerization of the terminal double bonds to double bonds situated in the interior of the macromolecule, via the intermediate formation of cationic centers in the macrom

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patent: 5191044 (1993-03-01), Rath et al.
patent: 5408018 (1995-04-01), Rath

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