Hydrofluorinated olefins (HFO's) as diluents for butyl rubber production
View Patent ↗A process for producing a copolymer involves contacting at least one isoolefin monomer with at least one multiolefin and/or β-pinene monomer in the presence of at least one Lewis acid and at least one initiator in a diluent. The diluent contains a hydrofluorinated olefin (HFO) comprising a tetrafluorinated propene. Copolymers produced by a process of the present invention have a cyclic oligomer content lower than comparable polymers produced in a butyl rubber slurry process using 1,1,1,2-tetrafluoroethane and/or methyl chloride as a diluent as well as a more favorable ratio of C21/C13. Hydrofluorinated olefins used in the present invention are better diluents for butyl slurry cationic polymerization than saturated hydro fluorocarbons.
1. A process for producing a copolymer, the process comprising contacting at least one isoolefin monomer with at least one multiolefin and/or β-pinene monomer in the presence of at least one Lewis acid and at least one initiator, and in a diluent comprising a tetrafluorinated propene.
2. The process according to claim 1 , wherein the tetrafluorinated propene comprises 1,3,3,3-tetrafluoro-1-propene (HFO-1234ze), 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf), 1,1,3,3-tetrafluoro-1-propene, 1,1,2,3-tetrafluoro-1-propene, 1,2,3,3-tetrafluoro-1-propene, or mixtures thereof.
3. The process according to claim 1 , wherein the tetrafluorinated propene comprises 1,3,3,3-tetrafluoro-1-propene (HFO-1234ze), 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf), or mixtures thereof.
4. The process according to claim 1 , wherein the tetrafluorinated propene comprises 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf).
5. The process according to claim 1 , wherein the at least one isoolefin monomer comprises an isoolefin having from 4 to 16 carbon atoms.
6. The process according to claim 1 , wherein the at least one isoolefin monomer comprises an isoolefin having from 4 to 7 carbon atoms.
7. The process according to claim 1 , wherein the at least one isoolefin monomer comprises isobutene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 4-methyl-1-pentene, or mixtures thereof.
8. The process according to claim 1 , wherein the at least one multiolefin and/or β-pinene monomer comprises a multiolefin having from 4-14 carbon atoms.
9. The process according to claim 1 , wherein the at least one multiolefin and/or β-pinene monomer comprises isoprene, butadiene, 2-methylbutadiene, 2,4-dimethylbutadiene, piperyline, 3-methyl-1,3-pentadiene, 2,4-hexadiene, 2-neopentylbutadiene, 2-methyl-1,5-hexadiene, 2,5-dimethyl-2,4-hexadiene, 2-methyl-1,4-pentadiene, 2-methyl-1,6-heptadiene, cyclopentadiene, methylcyclopentadiene, cyclohexadiene, 1-vinyl-cyclohexadiene or mixtures thereof.
10. The process according to claim 1 , wherein the at least one multiolefin and/or β-pinene monomer comprises indene, α-Methyl styrene, p-methyl styrene, chlorostyrene or mixtures thereof.
11. The process according to claim 1 , wherein the at least one multiolefin and/or β-pinene monomer comprises p-methyl styrene.
12. The process according to claim 1 , further comprising contacting at least one additional monomer with the at least one isoolefin monomer and the at least one multiolefin and/or β-pinene monomer.
13. The process according to claim 12 , wherein the at least one additional monomer comprises indene, α-Methyl styrene, p-methyl styrene, chlorostyrene or mixtures thereof.
14. The process according to claim 1 , wherein the Lewis acid comprises ethyl aluminum dichloride (EADC), diethyl aluminum chloride (DEAC) and/or mixtures thereof.
15. The process according to claim 1 , wherein the initiator comprises a proton source and/or cationogen.
16. The process according to claim 1 , wherein the monomers are polymerized at a temperature in a range of about −120° C. to about −50° C., preferably, in a range of about −100° C. to about −75° C., preferably in a range of about −98° C. to about −90° C. or preferably about −95° C. or about −75° C.
17. The process according to claim 1 , wherein the diluent further comprises methyl chloride.
18. The process according to claim 17 , wherein a ratio of methyl chloride to tetrafluorinated propene in the diluent is about 50:50.
19. The process according to claim 1 , wherein:
the tetrafluorinated propene comprises 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf);
the at least one isoolefin monomer comprises isobutene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 4-methyl-1-pentene, or mixtures thereof;
the at least one multiolefin and/or β-pinene monomer comprises isoprene, butadiene, 2-methylbutadiene, 2,4-dimethylbutadiene, piperyline, 3-methyl-1,3-pentadiene, 2,4-hexadiene, 2-neopentylbutadiene, 2-methyl-1,5-hexadiene, 2,5-dimethyl-2,4-hexadiene, 2-methyl-1,4-pentadiene, 2-methyl-1,6-heptadiene, cyclopentadiene, methylcyclopentadiene, cyclohexadiene, 1-vinyl-cyclohexadiene, indene, α-Methyl styrene, p-methyl styrene, chlorostyrene, or mixtures thereof;
the Lewis acid comprises ethyl aluminum dichloride (EADC), diethyl aluminum chloride (DEAC) and/or mixtures thereof;
the initiator comprises a proton source and/or a cationogen;
the monomers are polymerized at a temperature of about −98° C. to about −75° C.; and
the diluent further comprises methyl chloride, wherein a ratio of methyl chloride to 2,3,3,3-tetrafluoro-1-propene in the diluent is about 50.50.
20. A copolymer produced by the process as defined in claim 1 .