2,3,3,3-TETRAFLUORO-1-PROPENE AS DILUENT FOR THE PREPARATION OF NOVEL BUTYL RUBBERS

Abstract

The invention relates to an efficient polymerization process and its use to produce novel copolymers with a specific microstructure. In particular, the invention relates to butyl rubbers with novel microstructure, preferably those obtainable by copolymerization of monomer mixtures comprising isobutylene and isoprene in diluents comprising 2,3,3,3-tetrafluoro-1-propene. In a further aspect the invention relates to halogenated copolymers obtainable from such novel copolymers by halogenation.

Claims

1. Copolymers of isobutylene and isoprene having a copolymer sequence distribution defined by equation (I)
F=mA(1mA).sup.2(eq. I) wherein A is the molar ratio of isoprene to isobutylene in the copolymer as determined by .sup.1H NMR; and F is the isoolefin-isoprene-isoprene triad fraction in the copolymer as determined by .sup.13C NMR; and wherein m is in the range of
[1.35(0.03MOC)]m[1.15(0.03MOC)] whereby MOC is the content of isoprene in the copolymer in mol-% as determined by .sup.1H NMR.

2. The copolymers according to claim 1, wherein m is in the range of
[1.35(0.028MOC)]m[1.16(0.028MOC)].

3. The copolymers according to claim 1, wherein m is in the range of
[1.32(0.025MOC)]m[1.17(0.025MOC)].

4. The copolymers according to claim 1, wherein the isobutylene content is from 85.0 to 99.5 ma-% and the isoprene content is from 0.5 to 15.0 moL-%, or preferably the isobutylene content is from 88.0 to 99.0 mol.-% and the isoprene content is from 1.0 to 12.0 mol.-%.

5. The copolymers according to claim 4, wherein the isobutylene content is from 86.2 to 99,5 mol.-% and the isoprene content is 3.8 mol.-%, preferably the isobutylene content is from 86.3 to 99.0 mol.-% and the isoprene content is from 1.0 to 3,7 mol.-%.

6. The copolymers according to claim 1, wherein the copolymers are halogenated,

7. The halogenated copolymers according to claim 6, wherein an amount of halogen of such halogenated copolymers is in the range of from 0.1 to 8.0 wt.-%, preferably in the range of from 0.5 to 4 wt,-%, more preferably from 0.8 wt.-% to 3 wt.-%, even more preferably in the range of from 1.2 to 2.5 wt.-%, even still more preferably of from 1.5 wt.-% to 2.5% and most preferably of from 1.8 to 2.3 wt.-% by weight of the halogenated copolymer.

8. A process for the preparation of the copolymers according to claim 1, the process comprising: polymerizing monomers of a monomer mixture comprising isobutylene monomers and isoprene monomers, in a diluent at a mass ratio of monomer mixture to diluent of 5:95 to 95:5, and in the presence of an initiator system to form a copolymer solution comprising the copolymer, the diluent and residual monomers of the monomer mixture; separating the residual monomers of the monomer mixture and the diluent from the copolymer solution to obtain the copolymer whereby the polymerizing is carried out at a temperature 100 C. to 0 C., and whereby the diluent comprises at least 50.0 wt.-% of 2,3,3,3-tetrafluoro-1-propene.

9. The process according to claim 8, wherein for the diluent the content of aliphatic hydrocarbons having a bong point in the range of 5 C. to 95 C. at a pressure of 1013 hPa and being linear (n-alkanes) does not exceed 85 wt. % preferably does not exceed 70 wt.-%, more preferably 50 wt.-% and is yet even more preferably in range of from 10 to 50 wt.-%.

10. The process according to claim 8, wherein for the diluent the content of cyclic hydrocarbons having a boiling point in the range of 5 C. to 95 C. at a pressure of 1013 hPa does not exceed 25 wt-%, preferably does not exceed 20 wt.-% and is even more preferably in range of from 1 to 20 wt.-%.

11. The process according to claim 8, wherein the initiator system comprises ethyl aluminum sesquichloride, preferably generated by mixing equimolar amounts of diethyl aluminum chloride and ethyl aluminum dichloride, preferably in a diluent.

12. The process according to claim 8, wherein for the initiator system water and/or alcohols, preferably water is used as proton source.

13. The process according to claim 8, wherein the copolymers are halogenated and, after separating the residual monomers and the diluent from the copolymer solution to obtain the copolymers, the process further comprises halogenation of the copolymers.

14. The prgcess according to claim 13, wherein the halogenation is carried out using elemental chlorine (Cl.sub.2) or bromine (Br.sub.2) as halogenation agent.

15. A polymer product comprising the copolymers according to claim 1, either cured or uncured,

16. A polymer product comprising the halogenated copolymers according to claim 6, either cured or uncured.

17. The copolymers according to claim 3, wherein the isobutyiene content is 86.3 to 99.0 mol.-% and the isoprene content is from 1.0 to 3.7 mol.-%.

16. The halogenated copolymers according to claim 6, wherein an amount of halogen of such halogenated copolymers is 1.8 to 2.3 wt.-% of the total weight of the halogenated copolymer.

Description

EXAMPLES

Polymerization:

[0087] All polymerizations were done in a dried, inert atmosphere. The polymerizations were performed as batch reactions in 600 mL stainless steel reaction vessels, equipped with an overhead 4-blade stainless steel impeller driven by an external electrically driven stirrer. Reaction temperature was measured via a thermocouple. The reactor was cooled to the desired reaction temperature (95 C.) by immersing the assembled reactor into a pentane cooling bath. The temperature of the stirred hydrocarbon bath was controlled to 2 C. All apparatus in liquid contact with the reaction medium were dried at 150 C. for at least 6 hours and cooled in a vacuum-nitrogen atmosphere alternating chamber before use.

[0088] High purity isobutene and methyl chloride were received from a manufacturing facility and used as is.

[0089] The hydrofluorocarbon 1,1,1,2-tetrafluoroethane (>99.9% purity) (HFC-134a, Genetron@ 134a) and hydrofluoroolefin 2,3,3,3-tetrafluoro-1-propene (>99.99% purity) (HFO-1234yf, Solstice@ 1234yf Automotive Grade) were used as received. A

[0090] II were condensed and collected as liquids in the dry box. Isoprene (Sigma-Aldrich, >99.5% purity) was dried over activated 3A molecular sieves for several days and distilled under nitrogen. A 1.0 M solution of ethylaluminum dichloride in hexanes (Sigma-Aldrich) was used as received. A solution of HCl/CH.sub.2Cl.sub.2 was prepared by bubbling anhydrous HCl gas (Sigma-Aldrich, 99% purity) through a pre-dried Sure/SealTm bottle containing anhydrous CH.sub.2Cl.sub.2 (VWR). The HCl/CH.sub.2Cl.sub.2 solution was then titrated using 0.1 N NaOH (VWR) standard solution to determine its concentration.

[0091] The slurry polymerizations were performed by charging isobutene, isoprene, and liquefied diluent, (specified in each of the examples) into a chilled reaction vessel at polymerization temperature and stirred at a predetermined stirring speed between 500 to 900 rpm.

[0092] The initiator system solution were prepared in methyl chloride. The initiator system solution were prepared under the same temperature conditions as the reaction vessel by diluting the HCl/CH.sub.2Cl.sub.2 solution into an aliquot of methyl chloride and adding the 1.0 M solution of the ethylaluminum dichloride to a 1:4 molar ratio of HCl:EADC, followed by gentle swirling. The initiator system solution was used immediately. The initiator system solution was added to the polymerization using a chilled glass Pasteur pipette. The reaction was allowed to run for 5 minutes and stopped by the addition of 2 mL of a 1% sodium hydroxide in ethanol solution. Conversion is reported as weight percent of monomers converted to polymer during polymerization.

Examples 1 to 12

[0093] A series of polymerizations were performed in pure methylchloride, pure 1,1,1,2-tetrafluoroethane or pure pure 2,3,3,3-tetrafluoro1-propene at 95 C. All polymerizations were performed consistently as described above. Polymerizations were run with 180 mL diluent, 20 mL isobutene and various amounts of isoprene. The initiator system solution was prepared in 80 mL methylchloride by adding 11 mL of a 0.18 M HCl/CH.sub.2Cl.sub.2 solution and 8 mL of a 1.0 M hexane solution of ethylaluminum dichloride (EADC). 5 ml of said initiator system solution was used for all polymerizations according to examples 1 to 12. [0094] Isoprene incorporation was determined by .sup.1H-NMR spectrometry. NMR measurements were obtained using a Bruker DRX 500 MHz spectrometer (500.13 MHz) using CDCl.sub.3 solutions of polymers with the residual CHCl.sub.3 peak used as an internal reference. [0095] Triad sequence distributions were obtained from .sup.13C-NMR spectrometry using a Bruker DRX 500 MHz spectrometer (500.13 MHz) using CDCl.sub.3 solutions of polymer (6-8 wt %) containing 1.5% wt/v chromium (III) acetylacetonate as a relaxation agent. Data acquisition and processing were performed as described in U.S. Pat. No. 7,332,554..sup.(3)

[0096] The results are summarized in Table 1.

TABLE-US-00001 TABLE 1 Total Ratio Conversion Unsats.sup.1) BII.sup.2) BII/ at Ex. Diluent (Wt. %) (mol %) (%) m Unsats 40 C. 1 MeCl 58.9 2.55 4.99 2.12 1.96 13.86 2 MeCl 29.4 5.33 7.40 1.78 1.39 3 MeCl 58.4 5.61 7.41 1.47 1.32 4 MeCl 46.9 9.16 10.9 1.41 1.19 5 MeCl 45.1 12.7 13.3 1.29 1.05 6 HFC-134a 38.3 3.32 4.01 1.27 1.21 15.58 7 HFC-134a 34.1 6.98 7.88 1.26 1.13 8 HFC-134a 37.8 10.8 11.3 1.23 1.04 9 HFC-134a 13.1 15.5 14.0 1.10 0.90 10 HFO-1234yf <10 3.95 4.52 1.21 1.14 12.29 11 HFO-1234yf <10 8.75 8.24 1.04 0.94 12 HFO-1234yf <10 16.5 12.3 0.84 0.75 .sup.1)Total unsaturations = 1,4-isoprene (mol %) + isoprenoid (mol %) .sup.2)Calculated from the average BII fraction values determined for the quaternary and tertiary isoprene carbons