Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-07-13
2002-05-21
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S333000, C524S343000, C524S348000, C524S404000, C524S579000, C526S348600
Reexamination Certificate
active
06391951
ABSTRACT:
THIS INVENTION relates to copolymerization. It relates in particular to a copolymer of propylene and 1-pentene, to a process for producing such a copolymer, and to a polymer composition which includes such a copolymer.
According to a first aspect of the invention, there is provided, broadly, a copolymer of propylene and 1-pentene.
The copolymer may, more particularly, have a random arrangement of propylene and 1-pentene, ie it may be a random copolymer of propylene and 1-pentene. The copolymer may be thermoplastic, and may have crystalline and amorphous sequences.
The copolymer may further be characterized by the substantial absence of monomer sequences other than propylene and 1-pentene.
About 0.05% to 20% by mass of the copolymer may be derived from 1-pentene, with the balance thus being derived from propylene.
The melt flow index of the copolymer may be in the range of about 0.01 to about 200 g/10 minutes, preferably in the range 0.5 to about 60 g/10 minutes.
The copolymer may comply with the formula
IS>
0.5
Y+
5
where IS is the impact strength thereof, expressed in Kj/m
2
, and Y is the weight percent of 1-pentene in the copolymer. The copolymer may also have a haze value lower than 7.5% when measured according to ASTM 1003-92, on a film of 100 &mgr;m.
The copolymer may be that obtained by reacting propylene and 1-pentene in a reaction zone, while maintaining a pressure between 1 and 60 kg/cm
2
in the zone, at a reaction temperature between 0° C. and 100° C., and for a reaction time between 20 minutes and 8 hours, in the presence of a suitable Ziegler-Natta catalyst or catalyst system. Still more particularly, the copolymer may be that obtained by continuously varying, during the reaction of the propylene and the 1-pentene, the ratio of the concentration of the propylene to that of the 1-pentene.
Thus, according to a second aspect of the invention, there is provided a process for producing a copolymer, which process comprises reacting propylene and 1-pentene in a reaction zone, while maintaining a pressure between 1 and 60 kg/cm
2
in the zone, at a reaction temperature between 0° C. and 100° C., and for a reaction time between 20 minutes and 8 hours, in the presence of a suitable Ziegler-Natta catalyst or catalyst system.
The process may include continuously varying the ratio of the concentration of the propylene to that of the 1-pentene in the reaction zone, so that the copolymer has a random arrangement of propylene and 1-pentene. In other words, the copolymer is then a random copolymer of propylene and 1-pentene, which can also be referred to as ‘n-pentene-1’.
While the reaction temperature can be in the range of 0° C. to 100° C. as stated hereinbefore, it is preferably in the range of 20° C.-80° C., still more preferably in the range 40° C.-70° C.
Since propylene is a gas at atmospheric pressure, the reaction zone is thus provided by a closed reaction vessel, with the zone pressure being in said range of 1-60 kg/cm
2
. Preferably, the pressure is in the range 3-30 kg/cm
2
, more preferably in the range 6-14 kg/cm
2
.
The reaction will thus be continued for a sufficient period of time to obtain a desired degree of conversion of the monomers. Typically, the conversion can be in the range 10%-95%. Thus, the reaction time will normally be between said 20 minutes and 8 hours, preferably between 40 minutes and 2 hours.
The reaction is preferably carried out in a single reaction zone, ie a single stage reactor vessel is preferably used. The reaction can be effected in a batch fashion, with all the monomers, ie the propylene and 1-pentene, being added simultaneously at the start of the reaction to the reaction zone, and no product being removed therefrom during the course of the reaction. Thus, the continuous variation in the ratio of the concentration of the propylene to that of the 1-pentene during the reaction is achieved by virtue of the monomers being consumed at unequal rates during the reaction, ie the monomers have different reaction rates. Instead, the process may be a semi-continuous process, wherein at least one of the monomers is added continuously to the reaction zone over a period of time with the other monomer then either also being added continuously over the period of time or being added at the start of the reaction, and with no products being removed. The continuous variation in the relative concentrations of the monomers is then achieved through the unequal rates of consumption of the monomers during the reaction, as well as rates of addition of the monomers. In yet a further embodiment, the process may be a continuous process, involving the continuous addition of the monomers to the reaction zone, and the continuous removal of products therefrom. In such case, the continuous variation in the relative concentrations of the monomers is effected by means of the unequal rates of consumption thereof, as well as by the addition rates of the monomers and the withdrawal rate of product from the reaction zone.
The reaction is preferably also carried out in slurry phase. Accordingly, the monomers and/or the catalyst may be suspended in a suitable inert slurrying agent. The slurrying agent may be a saturated, aliphatic or cyclo-aliphatic liquid hydrocarbon. In particular the hydrocarbon may have from 2-12 carbon atoms. Most preferred are aliphatic hydrocarbons having 6 and 7 carbon atoms. The volume or proportion of slurrying agent used is not critical, but should be sufficient to permit good agitation of the resultant slurry, and efficient heat transfer. Thus, sufficient slurrying agent may be used to achieve a slurry concentration in the range of 4 g-400 g of polymer per liter of slurrying agent, preferably 50-250 g/l.
The molecular weight of the resultant random copolymer can be regulated by adding hydrogen to the reaction zone. The greater the amount of hydrogen added, the lower will be the molecular weight of the random copolymer. A hydrogen partial pressure of 0.1-2 kg/cm
2
is suitable for a reaction zone pressure of 3-30 kg/cm
2
.
Any Ziegler-Natta catalyst or catalyst system, suitable for propylene polymerization, can, at least in principle, be used. Thus, a catalyst system comprising a titanium-based Ziegler-Natta catalyst and, as a co-catalyst, an organo-aluminium compound, and wherein the atomic ratio of aluminium to titanium in the catalyst system is between 0.1:1 and 100:1, preferably 0.65:1 and 65:1, may be used.
Sufficient of the titanium-based Ziegler-Natta catalyst should then be used such that the concentration of titanium is at least 0.0001 mole %, based on the total monomer addition to the reaction zone. Preferably, the concentration thereof should be in the range 0.0003-0.15 mole % titanium.
Typical titanium components of the Ziegler-Natta catalyst are titanium trichlorides of &agr;, &bgr;, &ggr; and &dgr; type, and titanium trichlorides or titanium tetrachloride carried on a support. Catalyst support and activation can be effected in known fashion. For the preparation of a titanium catalyst, halides or alcoholates of trivalent or tetravalent titanium are normally used. TiCl
4
is especially preferred.
In addition to the trivalent and tetravalent titanium compounds and the support or carrier, the catalyst can also contain electron-donor compounds, e.g. mono or poly functional carboxyl acids, carboxyl anhydrides and esters, ketones, ethers, alcohols, lactones, or phosphorous or silicon organic compounds. Electron-donor compounds improve activity, stereoregularity and granulometric properties of the catalyst.
A preferred titanium-based catalyst is (TiCl
3
)
3
AlCl
3
commercially available with a content of 76.5-78.5 TiCl
3
weight percent. Another preferred titanium catalyst is &dgr;-TiCl
3
(AlCl
3
)⅓ (n-propyl benzoate), which is commercially available.
Typical organo aluminium compounds which can be used in combination with the titanium-based catalyst are compounds expressed by the formula Al R
m
X
3-m
wherein R is hydrogen or a hydrocarbon residue of 1-15 carbon atoms, X is a halogen atom or an alkoxy group of 1-15 carbon
Joubert Dawid Johannes
Potgieter Antonie Hermanus
Potgieter Ignatius Hendrik
Tincul Ioan
(Sasol Technology (Proprietary) Limited)
Harlan R.
Ladas & Parry
Wu David W.
LandOfFree
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