Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-12-22
2002-05-21
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S124300, C526S124900, C526S125600, C526S348000, C526S348600
Reexamination Certificate
active
06391987
ABSTRACT:
THIS INVENTION relates to polymerization. It relates in particular to a process for producing a propylene/1-pentene polymer, and to a polymer produced in such a process.
According to a first aspect of the invention, there is provided a process for producing a propylene/1-pentene polymer, which process comprises reacting propylene, as a first monomer reactant, with 1-pentene, as a second monomer reactant, in a reaction zone, in the presence of a Ziegler-Natta catalyst or catalyst system, to form the propylene/1-pentene polymer, with the reactants being in the vapour phase in the reaction zone while the reaction is in progress, and with no liquid component being present in the reaction zone while the reaction is in progress.
While the temperature in the reaction zone, ie the reaction temperature, can be in the range of 10° C. to 130° C., it is preferably in the range of 40 to 110° C., still more preferably in the range of 60° to 90° C.
While the pressure in the reaction zone, ie the reaction pressure can be in the range of 1 to 60 kg/cm
2
, it is preferably in the range of 3 to 40 kg/cm
2
, more preferably in the range of 6 to 30 kg/cm
2
.
The reaction zone may be stirred while the reaction is in progress. Preferably, the stirring of the reaction zone may be effected by means of a mechanical type of stirrer. Most preferred is a stirred reaction zone which provides an upward movement of the copolymer particles which are produced therein, without sedimentation of these particles at the bottom of the reaction zone occurring to a significant degree.
The reaction of propylene and 1-pentene is exothermic, and the process may thus include, if necessary, removing at least some of the heat of reaction. The removal of the heat of reaction may be effected by providing. internal or external coolers to the reaction zone; by withdrawing a portion of the gaseous monomer reactants from the reaction zone, cooling this portion, and recycling this portion to the reaction zone in cooled or liquefied form; or the like.
The reaction will be continued for a sufficient period of time to obtain a desired degree of conversion of the monomer reactants, hereinafter also referred to as monomers for brevity. Typically, the conversion can be in the range of 1% to 99%. Thus, the reaction time may be between 10 minutes and 48 hours, preferably between 20 minutes and 200 minutes.
The Applicant has found that different methods of introducing the monomer reactants into the reaction zone, give different performances of the process. Thus, the 1-pentene may be introduced into the reaction zone in vapour phase or it can be introduced into the reaction zone at least partially in liquid phase, with the liquid phase being evaporated in the reaction zone.
In one embodiment of the invention, both the monomer reactants may be introduced into the reaction zone in the vapour phase. Thus, the monomer reactants can then be preheated prior to introducing them into the reaction zone, to ensure that they are in vapour phase.
In one version of this embodiment of the invention, the propylene and 1-pentene may be preheated separately and introduced separately into the reaction zone.
In another version of this embodiment of the invention, the propylene and 1-pentene may be preheated separately, thereafter admixed, and then introduced together, ie as an admixture, into the reaction zone.
In still another version of this embodiment of the invention, the propylene and 1-pentene may be preheated together, ie after combining them to form an admixture, and thereafter introduced together, ie as the admixture, into the reaction zone.
In another embodiment of the invention, the monomer reactant(s) may be introduced into the reaction zone partly in the vapour phase, so that part of the monomer reactant(s) are introduced into the reaction zone in liquid phase, with this part being further evaporated in the reaction zone so that the reaction is performed with both monomer reactants in the vapour phase.
In one version of this embodiment of the invention, the propylene may be introduced into the reaction zone in the vapour phase, while the 1-pentene is introduced into the reaction zone separately in the liquid phase in such an amount that it rapidly evaporates in the reaction zone so as also to be in the vapour phase.
In another version of this embodiment of the invention, a major proportion of both propylene and 1-pentene may be introduced into the reaction zone in vapour phase, while a minor proportion of each of the monomers is introduced into the reaction zone in liquid phase in such an amount that it rapidly evaporate in the reaction zone so as also to be in the vapour phase.
It will thus be appreciated that while a portion of at least one of the monomer reactants can be introduced into the reaction zone in the liquid phase, any liquid monomer reactant that enters the reaction zone is rapidly vaporized so that all monomer reactants are in the vapour phase when they partake in the polymerization reaction. Additionally, the process is characterized thereby that no liquid component is present in the reaction zone while the reaction is in progress. By ‘liquid component’ is meant any component, whether capable of reacting with the monomer reactants or not, which is in liquid form at the reaction conditions prevailing in the reaction zone and which would remain in liquid form if introduced into the reaction zone. The liquid component does thus not include the monomer reactants, which can be introduced into the reaction zone in partly liquefied form as hereinbefore described, but which vaporize rapidly on entering the reaction zone. The liquid component also does not include the resultant propylene/1-pentene polymer, which can be in liquid form at the reaction conditions prevailing in the reaction zone. The liquid component also does not include any liquids present as part of the catalyst system, such as alkyl aluminium and stereoregulators, which remain liquid in the reaction zone but are present therein in very small or negligible amounts only, typically less than 0.5% (based on the total reaction zone content). The catalyst system also may contain a carrier such as heptane, but these carriers also rapidly vaporize on entering the reaction zone.
It will be appreciated that while the propylene/1-pentene polymer will normally be a copolymer of propylene and 1-pentene only, if may also, if desired, contain minor proportions of other monomers, which will then also be introduced into the reaction zone as monomer reactants and will then also be in the vapour phase while the reaction is in progress.
The 1-pentene may be that obtained by an appropriate process. Thus, for example, it may be that obtained from a Fischer-Tropsch synthesis reaction, typically that obtained from the SASOL (trade mark) Fischer-Tropsch synthesis reaction process.
Any Ziegler-Natta catalyst or catalyst system for propylene polymerization in vapour phase can, at least in principle, be used. However, a catalyst system comprising a titanium based Ziegler-Natta catalyst and, as a cocatalyst, an organo-aluminium compound, is preferred.
Typical titanium components of the Ziegler-Natta catalyst are titanium trichloride and titanium tetrachloride, which may be carried on a support. Catalyst support and activation can be effected in known fashion. For the preparation of the titanium catalyst, halides or alcoholates of trivalent or tetravalent titanium can be used. In addition to the trivalent and tetravalent titanium compounds and the support or carrier, the catalyst can also contain electron donor compounds, eg mono or polyfunctional carboxyl acids, carboxyl anhydrides and esters, ketones, ethers, alcohols, lactones, or organic phosphorous or silicon organic compounds.
An example of a preferred titanium-based Ziegler-Natta catalyst is TiCl
3
.1/3AlCl
3
.1/3(n-propyl benzoate [NPB]), which is commercially available.
However, the Applicant has also surprisingly found that when particular methods of catalyst preparation are used, process advantages in each particular embodiment or
Joubert Dawid Johannes
Potgieter Antonie Hermanus
Potgieter Ignatius Hendrik
Tincul Ioan
(Sasol Technology (Proprietary) Limited)
Ladas & Parry
Rabago R.
Wu David W.
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