The present invention relates to interpolymers (including copolymers) of alpha olefins (e.g. ethylene) with one or more C8-20 vinyl aromatic monomers (e.g. styrene), which polymers have one or more blocks of three vinyl aromatic monomers in a head to tail to tail insertion. (xe2x80x9cSSSxe2x80x9d).
Polymers of one or more alpha olefins are generally incompatible with polymers of one or more C8-20 vinyl aromatic monomers. As a result, it is difficult to blend or even laminate, for example polystyrene and polyethylene. There have been a number of attempts to prepare copolymers of, for example styrene and ethylene. Such polymers could lead to two different developments. The copolymer might have the properties sought after in the blend or the copolymer may be a suitable compatibilizer so that the blend could be prepared.
U.S. Pat. No. 6,066,709 issued May 23, 2000 assigned to Denki Kagaku Kogyo, Kabushiki discloses an ethylene styrene copolymer having from 1 to 55 mole % of an isotactic ES structure having a head to tail bond structure (e.g. ESSE). The polymers of the present invention have ratios of 13C NMR peaks at 38 ppm to 44 ppm of less than 2:1 and multiple peaks between 34 and 35 ppm indicating the polymer contains one or more blocks of three vinyl aromatic monomers in a head to tail to tail insertion. This is not disclosed or suggested by the reference.
U.S. Pat. No. 6,191,245 issued Feb. 20, 2001, to Campbell et al, assigned to the Dow Chemical Company teaches copolymers of one or more alpha olefins and one or more vinyl aromatic monomers which are substantially random (Col. 6 lines 45-48) and the tetrads occur exclusively in a 1, 2 (head to tail) manner. This teaches against the SS vinyl aromatic block of the present invention.
U.S. Pat. No. 5,703,187 issued Dec. 30, 1997, assigned to the Dow Chemical Company teaches pseudo random copolymers of styrene and ethylene. The specification teaches a particular distinguishing feature of pseudo random copolymers is that all the phenyl groups substituted on the polymer backbone are separated by 2 or more methylene units (Col. 13 lines 44-55). No vinyl aromatic monomer (e.g. styrene) is inserted in a head-to-tail-to-tail manner as required by the present invention.
U.S. patent application Ser. No. 6,235,855 B1 published May 22, 2001 discloses a process for producing an ethylene styrene interpolymer having isotactic styrene blocks prepared using bridged metallocene catalysts. The polymers of the present invention do not have isotactic styrene blocks and are prepared without using a bridged metallocene catalyst.
The present invention provides an interpolymer comprising:
1) from 30 to 70 weight % of one or more monomers selected from the group consisting Of C2-10 aliphatic alpha olefins;
2) from 70 to 30 weight % of one or more monomers selected from the group consisting Of C8-20 vinyl aromatic monomer which are unsubstituted or substituted by one or more substituents selected from the group consisting of C1-4alkyl radicals; and optionally;
3) from 0 to 10 weight % one or more monomers selected from the group consisting of C5-9 non-conjugated diolefins wherein said interpolymer;
i) contains one or more blocks of three vinyl aromatic monomers in a head to tail to tail insertion fashion (manner) characterized by having a 13C NMR ratio of the areas under the peaks at 38 ppm to 44 ppm of less than 2:1 and multiple peaks between 34 and 35 ppm.
The present invention further provides a process for preparing the above interpolymer comprising contacting a monomer mixture comprising from 0.8 to 0.6 mole fraction of one or more C8-20 vinyl aromatic monomer which are unsubstituted or substituted by one or more substituents selected from the group consisting of C1-4 alkyl radicals; from 0.4 to 0.2 mole fraction of one or more monomers selected from the group consisting of C2-10 aliphatic alpha olefins and optionally from 0 to less than 0.1 mole fraction one or more monomers selected from the group consisting of C5-9 non-conjugated diolefins with a catalyst comprising a phosphinimine compound of the formula;
Cp((R1)3Pxe2x95x90N)xe2x80x94Mxe2x80x94L2
wherein each R1 is independently selected from the group consisting of C3-6 alkyl radicals which are unsubstituted or substituted by a heteroatom, provided that there is a carbon phosphorus bond and the CPN bond angle is not less than 108xc2x0, Cp is selected from the group consisting of a cyclopentadienyl, indenyl and fluorenyl radicals which are unsubstituted or substituted by one or more substitutents selected from the group consisting of C1-6 alkyl radicals which are unsubstituted or substituted by one or more fluorine atoms; M is selected from the group consisting of Ti, Zr, and Hf, and each L is independently selected from the group consisting of a halogen atom, a hydrogen atom, a C1-10 alkyl radical, a C1-10 alkoxide radical, and a C6-10 aryl oxide radical, and at least one activator selected from the group consisting of:
(i) a mixture comprising a complex aluminum compound of the formula R22AlO(R2AlO)mAlR22 wherein each R2 is independently selected from the group consisting of C1-20 hydrocarbyl radicals and m is from 3 to 50, and a hindered phenol to provide a molar ratio of Al: hindered phenol from 2:1 to 5:1;
(ii) ionic activators selected from the group consisting of:
(A) compounds of the formula [R3]+ [B(R4)4]xe2x88x92 wherein B is a boron atom, R3 is a cyclic C5-7 aromatic cation or a triphenyl methyl cation and each R4 is independently selected from the group consisting of phenyl radicals which are unsubstituted or substituted with from 3 to 5 substituents selected from the group consisting of a fluorine atom, a C1-4 alkyl or alkoxy radical which is unsubstituted or substituted by a fluorine atom; and a silyl radical of the formula xe2x80x94Sixe2x80x94(R5)3; wherein each R5 is independently selected from the group consisting of a hydrogen atom and a C1-4 alkyl radical;
(B) compounds of the formula [(R8)tZH]+[B(R4)4]xe2x88x92 wherein B is a boron atom, H is a hydrogen atom, Z is a nitrogen atom or phosphorus atom, t is 2 or 3 and R8 is selected from the group consisting of C1-8 alkyl radicals, a phenyl radical which is unsubstituted or substituted by up to three C1-4 alkyl radicals, or one R8 taken together with the nitrogen atom may form an anilinium radical and R4is as defined above; and
(C) compounds of the formula B(R4)3 wherein R4 is as defined above; and
(iii) mixtures of (i) and (ii); in an inert hydrocarbyl medium at a temperature from 20xc2x0 C. to 150xc2x0 C. and a pressure from 15 psi to 15000 psi.