Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1988-12-06
1991-12-24
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526254, 526255, 526346, C08F 200, C08F 400
Patent
active
050753975
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to new radical initiators of polymerization of ethylenically unsaturated monomers.
BACKGROUND OF THE INVENTION
Recently increasing attention has focused on the search of new polymerization initiators, in particular of fluorinated olefins. Among such initiators the perfluoroalkyl radicals proved to be particularly interesting. At present, however, the generators of perfluoroalkyl radicals are often too stable, such as, for instance CF.sub.3 I and azomethane hexafluoride, which need too high working temperatures in polymerization. See for instance: Rossi and Golden Int. J. Chem. Kinetics 1979, page 775, Okafo and Whittle, Int. Journal of Chem. Kinetics, page 287 (1975) and W. A. Sheppard C. M. Sharts "Organic fluorine Chemistry" page 89 (1969).
It is also common knowledge that use may be made of perfluoroacylperoxides, which present some advantages in comparison with the above mentioned initiators; they are, however, expensive and cannot be prepared easily, moreover they may be hydrolyzed with ease. Their application on industrial scale proves to be limited.
Therefore in industrial processes use is made of non-fluorinated initiators, such as persulfates in the dispersion polymerization of fluorinated monomers, for instance of C.sub.2 F.sub.4 or C.sub.2 F.sub.4 /C.sub.3 F.sub.6. In that case, reactive terminals are introduced, which decrease polymer characteristics, and therefore expensive treatments of the polymer are required, in order to convert the terminal groups into non-reactive groups (D. I. Mc. Cane Encyclopedia of Polymer Science and Technology vol. 13 pages 623-670).
In European Patent 121,898 a perfluoroalkyl radical was synthetized and isolated, which was stable at room temperature and was proposed as a polymerization initiator.
This product, however, is obtained with low yields and because the product is a perfluoroalkyl radical, it requires some precautions as regards storage and treatment, in order to avoid its decomposition. Moreover the radical obtained according to this process, cannot easily be separated from the reaction raw product. This separation is generally necessary, owing to the presence of perfluoroolefines together with the perfluoroalkyl radical, as these perfluoroolefins may interfere with the polymerization monomers.
DESCRIPTION OF THE INVENTION
The object of the present invention is a process for the polymerization of ethylenically unsaturated monomers comprising as polymerization initiator a branched perfluoroalkane or a mixture of branched perfluoroalkanes having adjacent two quaternary carbon atoms or a quaternary carbon atom and a tertiary carbon atom, said perfluoroalkane having at least 9 carbon atoms.
Such perfluoroalkanes, being stable at room temperature, having practical and unlimited storage properties, do not require the precautions that were necessary for the polymerization initiators of the prior art, but can be introduced as such into the reaction medium and only at the polymerization temperature are they able to generate radicals. Known perfluoroalkanes belonging to this class are for example the following: ##STR1## This product is prepared according to U.S. Pat. No. 3,962,358. ##STR2## This product is prepared according to U.S. Pat. No. 3,950,235.
Other branched perfluoroalkanes belonging to this class are the new compounds having the following formulas: ##STR3##
In particular compounds (V) and (VI), having adjacent two tertiary and quaternary carbon atoms, although stable at room temperature, decompose at temperatures >70.degree. C. preferably at temperatures >100.degree. C., thereby generating radicals.
For instance compounds (V) and (VI), if heated at temperatures ranging from 100.degree. to 160.degree. C., decompose probably undergoing a homolytic scission of the C--C bound between the tertiary and quaternary carbon atoms according to the following scheme: ##STR4## and after some time the following products are obtained, in the same ratio: ##STR5##
The perfluoroalkanes, having the above men
REFERENCES:
patent: 3917724 (1975-11-01), Martini
patent: 3950235 (1976-04-01), Benninger
patent: 3962358 (1976-06-01), Von Halasz
patent: 4736004 (1988-04-01), Scherer, Jr. et al.
Tonelli Claudio
Tortelli Vito
Ausimont S.p.A.
Sarofim N.
Schofer Joseph L.
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