Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1988-06-08
1989-08-15
Smith, Edward J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526125, 526151, 5263482, 5263484, 5263485, 526901, 526904, 526916, C08F 234, C08F21016
Patent
active
048576115
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a gas fluidised bed process for the production of copolymers of ethylene, propylene and/or 1-butene and alpha-olefins comprising from 5 to 8 carbon atoms, these copolymers having a density between 0.900 and 0.935 and having excellent mechanical and optical properties.
It is known that low-density polyethylene (LDPE), that is to say of a density less than 0.940, obtained according to a process for polymerizing ethylene by radical-forming catalysis under high pressure and at high temperature, possesses good optical properties such as good transparency for a slender thickness, but on the other hand has comparatively mediocre mechanical properties, especially as regards tearing strength, perforation and impact resistance, making it difficult to obtain finished objects with a very thin wall, such as film.
It is further known that copolymers of ethylene and propylene and/or 1-butene of the "linear low density polyethylene" type (LLDPE), with a density between 0.900 and 0.940, obtained by the copolymerisation of ethylene and alpha-olefins in the presence of a catalyst of the Ziegler-Natta type, generally possess mechanical properties which are superior to those of the LDPE's, but unfortunately they have mediocre optical properties.
It is known that LLDPE film prepared from a copolymer of ethylene and a higher alpha-olefin, comprising from 5 to 18 carbon atoms, such as 1hexane, 4-methyl-1-pentene or 1-octene has improved optical properties and especially, improved transparency. Such an LLDPE, furthermore, has the advantage of having tearing strength, perforation and impact resistances which are notably superior to those of the LLDPE's obtained by copolymerising ethylene, propylene and/or 1-butene.
It is also known that copolymers of ethylene, propylene and/or 1-butene and a higher alpha-olefin comprising 5 to 18 carbon atoms, with a density comprised between 0.900 and 0.940, not only have excellent optical properties when these copolymers are converted into film, but also mechanical properties which are as good as, if not better than those of the LLDPE's obtained by copolymerising ethylene and a higher alpha-olefin comprising from 5 to 18 carbon atoms.
These copolymers can be produced in solution in a solvent medium of a liquid hydrocarbon. The process of this type, according to which the copolymer is produced in the form of a solution in the liquid hydrocarbon medium, involves difficult operations for recovering the said copolymer from the solution. Moreover, a substantial part of the copolymer remains dissolved in the solvent, which renders the recovery and purification operations of the said solvent difficult.
It is also possible to produce in the gas phase copolymers of ethylene, propylene and/or 1-butene and a higher alpha-olefin comprising 5 to 12 carbon atoms, having a density comprised between 0.900 and 0.940. These copolymers are obtained by means of a copolymerisation reaction in the presence of a catalyst system comprising the presence of titanium tetrachloride and possibly a halogenating agent or an electron donor agent, and of particles with a broad particle size distribution. Hence such a catalyst cannot be used to carry out fluidised bed polymerisation reactions except as relatively low fluidisation speeds, for example of less than 3 times the minimum fluidisation speed, in order to avoid any substantial loss of particles from the fluidised bed by gas entrainment.
To satisfactorily remove the heat of reaction, it is then necessary to employ a system of mechanical agitation and/or a device for introduction, recovery and recycling of one or more readily volatile liquids. Accordingly, a solid catalyst of this type is not very suitable for use in a gas-phase fluidised-bed copolymerisation reactor because of its structure and composition. In point of fact a solid catalyst of this kind, prepared in the absence of reducing agent, comprises a tetravalent titanium salt, deposited on the surface of the magnesium chloride support in a relatively small quantity, such that the at
REFERENCES:
patent: 4021599 (1977-05-01), Kockhar et al.
patent: 4359561 (1982-11-01), Fraser et al.
patent: 4438243 (1984-03-01), Kashiwa et al.
patent: 4469855 (1984-09-01), Cooper
patent: 4525547 (1985-06-01), Kato et al.
patent: 4567243 (1986-01-01), Pullukat et al.
patent: 4642328 (1987-02-01), Morterol et al.
patent: 4721763 (1988-01-01), Bailly et al.
Encyclopedia of Polymer Science and Technology, J. Wiley & Sons, New York, vol. 9, pp. 47, 48, 84, 118, 119, (1968).
Durand Daniel C.
Morterol Frederic R.
BP Chemicals Limited
Smith Edward J.
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