Process and catalyst for producing syndiotactic polymers

Claim 2

A catalyst for use in the syndiotactic propagation of a polymer chain comprising an unbalanced metallocene stereori­gid metallocene characterized by a metallocene ligand having sterically dissimilar ring structures joined to a coordinating transition metal atom, each of said ring structures being a sub­stituted cyclopentadienyl ring and one of said ring structures being a substituted cyclopentadienyl group which is sterically different from the other of said cyclopentadienyl groups, and each of said ring structures being in a stereorigid relationship relative to said coordinating metal atom to prevent rotation of said ring structure, said stereorigid relationship being imparted by the substituent groups on said ring structure.

Claim 3

The catalyst of Claim 1, wherein said catalyst comprises an unbalanced metallocene cation and a stable noncoor­dinating counter anion for said metallocene cation.

Claim 4

The catalyst of Claim 1, in which said unbalanced stereorigid metallocene is a neutral metallocene.

Claim 5

The catalyst of Claim 1, wherein said transition metal is a Group 4 or Group 5 metal from the Periodic Table of Elements.

Claim 6

The catalyst of Claim 4, wherein said transition metal is titanium, zirconium or hafnium.

Claim 7

The catalyst of Claim 1, wherein the substituent groups of said ring structures impart stereorigidity by means of a sterically hindered relationship between said ring structures.

Claim 8

The catalyst of Claim 6, wherein said catalyst comprises an unbalanced metallocene cation and a stable noncoor­dinating counter anion for said metallocene cation.

Claim 9

The catalyst of Claim 7, wherein said transition metal is titanium, zirconium or hafnium.

Claim 10

The catalyst of Claim 1, wherein the substituent groups of said ring structures are sufficiently bulky to induce low kinetic energy states to said ring structures so as to pre­vent rotation of said rings about their coordination axes at a temperature which is less than -20°C.

Claim 11

The catalyst of Claim 1, wherein said catalyst comprises an unbalanced metallocene cation and a stable noncoor­dinating counter anion for said metallocene cation.

Claim 12

The catalyst of Claim 1, in which said unbalanced stereorigid metallocene is a neutral metallocene.

Claim 13

The catalyst of Claim 1, characterized by the for­mula: (Cps x ) (CpS′ y ) MeQ k or (CpT x ) (CpT′ y ) MeQ k wherein: C p is a substituted cyclopentadienyl ring; each S and T is the same or different and is a hydrocarbyl radical having from 1-20 carbon atoms; each S′ and T′ is the same or different and is a hydrocarbyl radical having from 1-20 carbon atoms and selected such that C p S x is a sterically different ring than C p S′ y and is in a steri­cally hindered relationship relative to C p S y sufficient to prevent rotation of said rings and impart stereorigi­dity to said catalyst; and C p T x and C p T′ y are sterically different rings and are both at sufficiently low kinetic energy states induced by the substituent groups T and T′ so as to prevent rotation of said rings about their coordination axes at the temperature which is less than -20°C; Me is a Group 4, 5, or 6 metal from the Periodic Table of Elements; each Q is a hydrocarbyl radical hav­ing from 1-20 carbon atoms or a halogen; x is from 1 to 5; y is from 1 to 5; k is from 0 to 3.

Claim 14

The catalyst of Claim 12, wherein Me is titanium, zirconium, or hafnium and k is 1 or 2.

Claim 15

The catalyst of Claim 13, wherein each Q is a methyl or ethyl group or chlorine.

Claim 16

The catalyst of Claim 14, wherein each Q is a methyl group or chlorine.

Claim 17

The catalyst of Claim 12 characterized by the for­mula: (CpS x ) (CpS′ y ) MeQ k .

Claim 18

The catalyst of Claim 16, wherein x is 2 or 3 and y is from 3-5.

Claim 19

The catalyst of Claim 17, wherein S and S′ are alkyl or alkylsilanyl groups containing from 1-8 carbon atoms.

Claim 20

The catalyst of Claim 12, characterized by the for­mula: [(CpS x ) (CpS′ y ) MeQ k ] +p⁻ or [CpT x ) (CpT′ y ) MeQ k ]⁺p⁻ wherein: Cp, S, S′, T, T′, x, y, Me, and Q are the same as spe­cified in Claim 8, k is from 0 to 2; and P is a stable noncoordinating counter anion.

Claim 21

The catalyst of Claim 19, wherein Q is a titanium, zirconium, or hafnium and k is 1.

Claim 22

The catalyst of Claim 19, characterized by the formula: [(CpS x ) (CpS′ y ) MeQ k ]⁺p⁻.

Claim 23

The catalyst of Claim 21, wherein Q is a halogen or a methyl or ethyl group.

Claim 24

The catalyst of Claim 22, wherein Q is a methyl group or chlorine.

Claim 25

The catalyst of Claim 23, wherein S and S′ are alkyl or alkylsilanyl groups containing from 1 to 8 carbon atoms.

Claim 26

A process for the syndiotactic propagation of a polymer chain derived from an ethylenically unsaturated monomer comprising: (a) providing a catalyst comprising an unbalanced stereorigid metallocene characterized by a metallocene ligand having sterically dissimilar ring structures joined to a coor­dinating transition metal atom, each of said ring structures be­ing a substituted cyclopentadienyl group which is sterically different from the other of the cyclopentadienyl groups, and each of said ring structures being in a stereorigid relationship rela­tive to said coordinating metal atom to prevent rotation of said ring structure, said stereorigid relationship being imparted by substituent groups in said ring structures. (b) contacting said catalyst in a polymerization reaction zone with an ethylenically unsaturated monomer which contains 3 or more carbon atoms or which is a substituted vinyl compound and maintaining said reaction zone under polymerization conditions to produce syndiospecific polymerization of said monomer.

Claim 27

A process for the syndiotactic propagation of a polymer chain derived from an ethylenically unsaturated monomer comprising: (a) providing a catalyst comprising an unbalanced stereorigid metallocene characterized by a metallocene ligand having sterically dissimilar ring structures joined to a coor­dinating transition metal atom, each of said ring structures be­ing a substituted cyclopentadienyl group which is sterically different from the other of the cyclopentadienyl groups, and each of said ring structures being in a stereorigid relationship rela­tive to said coordinating metal atom to prevent rotation of said ring structure, said stereorigid relationship being imparted by substituent groups in said ring structures. (b) contacting said catalyst in a polymerization reaction zone with an ethylenically unsaturated monomer which contains 3 or more carbon atoms or which is a substituted vinyl compound and maintaining said reaction zone under polymerization conditions to produce syndiospecific polymerization of said monomer.

Claim 28

The process of Claim 25, wherein the transition metal of said catalyst is a Group 4 or Group 5 metal from the Periodic Table of Elements.

Claim 29

The process of Claim 26, wherein the transition metal of said catalyst is titanium, zirconium or hafnium.

Claim 30

The process of Claim 25, wherein the substituent groups of the ring structures of said catalyst impart stereorigi­dity to said catalyst by means of a sterically hindered rela­tionship between said ring structures.

Claim 31

The process of Claim 25, wherein the substituent groups of the substituted cyclopentadienyl rings of said catalyst are sufficiently bulky to induce low kinetic energy states to said ring structures so as to prevent rotation of said ring structures about their coordination axes at the temperature of the polymerization reaction zone in step (b) of Claim 19.

Claim 32

The process of Claim 25, wherein said catalyst com­prises an unbalanced metallocene cation and a stable noncoor­dinating counter anion for said metallocene cation.

Claim 33

The method of Claim 25, wherein said ethylenically unsaturated monomer is a C 3⁺ hydrocarbon.

Claim 34

The method of Claim 31, wherein said ethylenically unsaturated monomer is a vinyl aromatic compound.

Claim 35

The method of Claim 32, wherein said vinyl aromatic compound is styrene.

Claim 36

The method of Claim 25, wherein said ethylenically unsaturated monomer is a substituted vinyl compound.

Claim 37

The method of Claim 34, wherein said substituted vinyl compound is vinyl chloride.

Claim 38

The method of Claim 25, wherein said ethylenically unsaturated monomer is a C 3⁺ alpha olefin.

Claim 39

The method of Claim 36, wherein said C 3⁺ alpha ole­fin is propylene.

Claim 40

A process for the production of syndiotactic poly­propylene comprising: (a) providing a stereorigid cationic metallocene catalyst characterized by the formula: (CpS x ) (CpS′ y ) MeQ k or (CpT x ) (CpT′ y ) MeQ k wherein: Cp is a cyclopentadienyl or a substituted cyclopenta­dienyl ring; each S or T is the same or different and is a hydrocarbyl or substituted radical having from 1-20 carbon atoms; each S′ or T′ is the same or different and is a hydrocarbyl or substituted hydrocarbyl radical hav­ing from 1-20 carbon atoms and selected such that CpS x is a sterically different ring than CpS′ y and is in a sterically hindered relationship relative to CpS′ y sufficient to prevent rotation of said rings and impart stereorigidity to said catalyst and C p T x and CpT′y are sterically different rings and are both at sufficiently low kinetic energy states induced by the substituent groups T and T′ so as to prevent rotation of said rings about their coordination axes at the temperature of the polymerization reaction zone in step (b); Me is a Group 4, 5, or 6 metal from the Periodic Table of Elements; each Q is a hydrocarbyl group having from 1-20 carbon atoms or is a halogen; x is from 1 to 5; k is from 0 to 3; and (b) contacting said catalyst with propylene in a polymerization reaction zone under polymerization reaction con­ditions to produce syndiotactic polypropylene.

Claim 41

A process for the production of syndiotactic poly­propylene comprising: (a) providing a stereorigid cationic metallocene catalyst characterized by the formula: (CpS x ) (CpS′ y ) MeQ k or (CpT x ) (CpT′ y ) MeQ k wherein: Cp is a cyclopentadienyl or a substituted cyclopenta­dienyl ring; each S or T is the same or different and is a hydrocarbyl or substituted radical having from 1-20 carbon atoms; each S′ or T′ is the same or different and is a hydrocarbyl or substituted hydrocarbyl radical hav­ing from 1-20 carbon atoms and selected such that CpS x is a sterically different ring than CpS′ y and is in a sterically hindered relationship relative to CpS′ y sufficient to prevent rotation of said rings and impart stereorigidity to said catalyst and C p T x and CpT′y are sterically different rings and are both at sufficiently low kinetic energy states induced by the substituent groups T and T′ so as to prevent rotation of said rings about their coordination axes at the temperature of the polymerization reaction zone in step (b); Me is a Group 4, 5, or 6 metal from the Periodic Table of Elements; each Q is a hydrocarbyl group having from 1-20 carbon atoms or is a halogen; x is from 1 to 5; k is from 0 to 3; and (b) contacting said catalyst with propylene in a polymerization reaction zone under polymerization reaction con­ditions to produce syndiotactic polypropylene.

Claim 42

The process of Claim 38, wherein Me is zirconium, titanium or hafnium and k is 1 or 2.

Claim 43

The process of Claim 39, wherein each k is a halo­gen or a methyl or ethyl group.

Claim 44

The method of Claim 38, wherein said catalyst is characterized by the formula: [(CpS x ) (CpS′ y ) MeQ k ]⁺p⁻ or [CpT x ) (CpT′y) MeQ k ]⁺p⁻ wherein: Cp S, S′, T, T′, x, y, Me, and Q are the same as spe­cified in Claim 32. K is from 0 to 2; and P is a stable noncoordinating counter anion.

Claim 45

The process of Claim 41, wherein Me is titanium, zirconium, or hafnium and k is 1.

Claim 46

The method of Claim 42, wherein said catalyst is characterized by the formula: [(CpS x ) (CpS′y) MeQ k ]⁺p⁻.

Claim 47

The process of Claim 42, wherein Q is a halogen or a methyl or ethyl group.

Claim 48

The process of Claim 42, wherein Q is a chlorine or methyl group.