Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1998-11-24
2001-02-13
Teskin, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S068000, C526S078000, C526S194000, C526S185000, C526S209000, C526S237000, C526S348700
Reexamination Certificate
active
06187881
ABSTRACT:
The present invention relates to a process for the polymerization of olefin(s) which is particularly suitable for the manufacture of polybutene or polyisobutene.
BACKGROUND OF THE INVENTION
It is known to polymerize a mixture of butenes in solution in a boiling liquid hydrocarbon polymerization medium, especially for manufacturing a liquid polybutene or polyisobutene. In general the solution polymerization is carried out continuously in a reactor with the aid of a catalyst of cationic type and optionally of a cocatalyst. A reaction instability has very frequently been observed in the polymerization reactor in such a process. This instability can be characterized especially by the manufacture of a polymer of a nonuniform quality, which has a molecular weight distribution which is too broad, generally with catalyst residues or chlorine residues in a quantity which is too large. It may also be characterized by difficulties in control of some polymerization parameters, such as the polymerization temperature, the mean residence time of the polymer in the reactor or the withdrawal of the polymer out of the reactor.
SUMMARY OF THE INVENTION
After long studies it has surprisingly been found that these problems were linked with the presence of a foam which forms above the reaction liquid phase and which occupies a large proportion or even the whole of the reactor volume. This foam formation causes an instability of the reaction and a heterogeneity of the liquid hydrocarbon polymerization medium, which is reflected especially in a density gradient. These phenomena thus promote the production of a polybutene or polyisobutene of poor quality, which has in particular a breadth of the molecular weight distribution which is too broad and not compatible with some applications. Furthermore, the utilization of such a process is made difficult, for example, by loss of priming of the pumps which convey the liquid hydrocarbon polymerization medium, especially a loss of priming of the pump for withdrawing the polymer.
A process has now been found which allows the abovementioned problems to be solved. In particular the process makes it possible to manufacture, in improved reaction stability conditions, a polybutene or polyisobutene of a stable and desired quality, which has in particular a narrow molecular weight distribution generally with a very low catalyst residue or chlorine content.
The process of the invention permits a stabilization of the polymerization reaction and hence better control of this reaction. Furthermore, taking into account the fact that the polymerization reaction is stabilized, the liquid hydrocarbon polymerization medium is more homogeneous. As a result, the mean residence time of the polymer in the polymerization reactor can be decreased. The process of the invention can thus permit an increase in the polymer production capacity of the reactor.
The present invention relates therefore to a process for producing an olefin polymer of a low polydispersity index (i.e. a narrow molecular weight distribution) having low catalyst residues and/or low chlorine content by the polymerization of olefin(s), especially C
4
olefin(s), said process being carried out in solution, in the presence of a cationic catalyst, in a reactor containing a liquid phase comprising a liquid boiling hydrocarbon polymerization medium and having a vapor space above said liquid phase, characterized in that the polymerization is carried out in the presence of a non-mechanical agent capable of suppressing foam formation during said polymerization.
The present invention also relates to a process for reducing the polydispersity index of an olefin polymer having low catalyst residues and/or low chlorine content in a solution polymerization of olefin(s), especially C
4
olefin(s), said process being carried out in the presence of a cationic catalyst in a reactor containing a liquid phase comprising a liquid boiling hydrocarbon polymerization medium and having a vapor space above said liquid phase, characterized in that the polymerization is carried out in the presence of a non-mechanical agent capable of suppressing foam formation during said polymerization.
More particularly the agent capable of suppressing foam in the present invention excludes the use of a mechanical means e.g. stirring for imparting shearing forces to foam accumulating in the vapor space of the reactor.
According to a first embodiment of the present invention, the agent capable of suppressing foam formation preferably is a liquid hydrocarbon spray introduced into the vapor space above the liquid phase in the reactor.
REFERENCES:
patent: 2479418 (1949-08-01), Schutze
patent: 2529318 (1950-11-01), Tegge
patent: 3259614 (1966-07-01), Pollock
patent: 3962200 (1976-06-01), DeZarauz
patent: 4058652 (1977-11-01), Smith et al.
patent: 4220580 (1980-09-01), Rowatt
patent: 4222986 (1980-09-01), Smith et al.
patent: 4400493 (1983-08-01), Abernathy, Jr. et al.
patent: 5087678 (1992-02-01), Noguki et al.
patent: 5378779 (1995-01-01), Fauth et al.
patent: 44 26 756 A1 (1996-02-01), None
patent: 0 034 061 (1981-08-01), None
patent: 1 244 418 (1960-09-01), None
patent: 2 0 8 9 7 6 4 (1971-12-01), None
patent: 2 3 4 0 9 5 7 (1977-09-01), None
patent: 884 116 (1961-12-01), None
patent: 2 134 121 (1984-08-01), None
patent: WO 92 08743 (1982-05-01), None
Colman Derek Alan
Metzinger Pascal
Nater Bob
BP Chemicals Limited
Nixon & Vanderhye
Teskin Fred
LandOfFree
Process for polymerizing olefins does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for polymerizing olefins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for polymerizing olefins will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2602866