Syndiotactic propylene polymers and lubricating oils comprising the same

Abstract

This disclosure relates to syndiotactic polymers containing units derived from propylene and units derived from C.sub.4 to C.sub.20 alpha olefins. The polymers can be prepared is slurry or solution polymerization processes using a zirconium-containing metallocene catalyst system. The polymers have a melt flow rate as determined by ASTM D-1238 (230 C., 2.16 kg) of from about 0.1 to about 20 g/10 min. The syndiotactic polymers are useful as viscosity index improvers.

Claims

1. A lubricating oil composition comprising: (i) at least 50 wt % of a base oil based on the weight of the lubricating oil; and (ii) a syndiotactic polymer containing units derived from at least one -olefin having 4 to 10 carbon atoms and 50 mol % of units derived from propylene, wherein the polymer has a melt flow rate, as determined by ASTM D-1238 (2.16 kg, 230 C.), of about 1 g/10 m to about 10 g/10 min, and wherein the lubricating oil composition comprises about 0.1 wt % to about 10 wt % of the polymer based on the weight of the lubricating oil composition; wherein the polymer is produced by a polymerization process comprising contacting propylene and at least one -olefin having 4 to 10 carbon atoms with a catalyst system comprising a precatalyst compound and an activator in a reactor; wherein the precatalyst compound is selected from those having the structure of formula (1), (2), (3), or (4); wherein structure (1) has a Cs or pseudo-Cs symmetry and the following formula (1): ##STR00016## wherein M is a zirconium; L.sup.1 is a unsubstituted fluorenyl, unsubstituted heterocyclopentapentalenyl, unsubstituted heterofluorenyl, substituted fluorenyl, substituted heterocyclopentapentalenyl, or substituted heterofluorenyl ligand with one or more symmetric or pseudo symmetric substituents, each substituent group being, independently, a radical group which is a hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl or germylcarbyl, and optionally two or more adjacent substituents may join to form a substituted or unsubstituted, saturated, partially unsaturated or aromatic, cyclic or polycyclic substituent; L.sup.2 is a cyclopentadienyl ring or a substituted cyclopentadienyl ring with one or more symmetric or pseudo symmetric substituents in the 2 and 5 positions of the ring, each substituent group being, independently, a radical group which is a hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl or germylcarbyl; G is a bridging group; and X are, independently, halogen, alkoxide, aryloxide, amide, phosphide, hydride radicals, hydrocarbyl radicals, substituted hydrocarbyl radicals, halocarbyl radicals, substituted halocarbyl radicals, silylcarbyl radicals, substituted silylcarbyl radicals, germylcarbyl radicals, or substituted germylcarbyl radicals; or both X are joined and bound to the metal atom to form a metallacycle ring containing from 3 to 20 carbon atoms; or both together can be an olefin, diolefin or aryne ligand; or both X can also be joined to form a anionic chelating ligand; wherein structure (2) has Cs or pseudo-Cs symmetry and the following formula (2): ##STR00017## wherein: M, L.sup.1, G, and X are the same as in structure (1); J is a heteroatom from group 15; R is a radical group which is a hydrocarbyl, substituted hydrocarbyl, halocarbyl, or substituted halocarbyl; and L is a neutral Lewis base and w represents the number of L bonded to M where w is 0, 1, or 2, and optionally any L and any X may be bonded to one another; wherein structure (3) has Cs or pseudo-Cs symmetry and the following formula (3): ##STR00018## wherein: M and X are the same as in structure (1); L.sup.3 is a cyclopentadienyl ring optionally substituted in the 4 position of the ring, the substituent group being chosen from a radical group which is a hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl or germylcarbyl; L.sup.4 is a substituted cyclopentadienyl ring with symmetric or pseudo symmetric substituents in the 3 and 5 positions of the ring, each substituent group being, independently, a radical group which is a hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl or germylcarbyl; and G and G are bridging groups; and wherein structure (4) has C2 symmetry and the following formula (4): ##STR00019## wherein: X is the same as in structure (1); M is titanium; O is oxygen; N is nitrogen; R.sup.1 is a radical group which is a hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl or germylcarbyl; R.sup.2 is a radical group which is a hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl or germylcarbyl; and RL.sup.3, R.sup.4 and R.sup.5 are independently hydrogen or a radical group which is a hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl or germylcarbyl.

2. The lubricating oil composition of claim 1, wherein the at least one -olefin comprises 1-hexene.

3. The lubricating oil composition of claim 1, wherein the lubricating oil composition comprises about 0.5 wt % to about 5 wt % of the polymer based on the weight of the lubricating oil composition.

4. The lubricating oil composition of claim 1, wherein the base oil is selected from Group II base oil, Group III base oil, Group IV base oil, Group V base oil, and combinations thereof.

5. The lubricating oil composition of claim 1, wherein the polymer has a thickening efficiency of greater than 1.5.

6. The lubricating oil composition of claim 1, wherein the lubricating oil composition has at least one of: a kinematic viscosity at 40 C., as measured by ASTM D445-3, of greater than 50 cSt, and a kinematic viscosity at 100 C., as measured by ASTM D445-5, of greater than 10 cSt.

7. The lubricating oil composition of claim 1, wherein the lubricating oil composition has a viscosity index, as calculated by ASTM D2270, of greater than 120.

8. The lubricating oil composition of claim 1, wherein the precatalyst compound has the structure of formula (1) and has Cs or pseudo-Cs symmetry of formula (1a) or (1b); wherein structure (1a) has the following formula (1a): ##STR00020## wherein each R.sup.a and R.sup.b are selected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl, germylcarbyl or polar radicals, and optionally two or more adjacent substituents may join to form a substituted or unsubstituted, saturated, partially unsaturated or aromatic, cyclic or polycyclic substituent, with the proviso that each R.sup.a is the same and each R.sup.b is the same and allow the compound to be Cs-symmetric or pseudo Cs-symmetric; each R.sup.c is a symmetric or pseudo symmetric substituent with respect to the other and is selected from hydrogen or a hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl or germylcarbyl radicals; and each R.sup.d is a symmetric or pseudo symmetric substituent with respect to the other and is selected from hydrogen or a hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl or germylcarbyl radicals; and wherein structure (1b) has the following formula (1b): ##STR00021##

9. The lubricating oil composition of claim 1, wherein the precatalyst compound has the structure of formula (3) and has Cs or pseudo-Cs symmetry of the following structure (3a): ##STR00022## wherein R.sup.e is selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl, or germylcarbyl radicals; each R.sup.f and R.sup.g are selected from hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl, or germylcarbyl, with the proviso that each R.sup.f and R.sup.g are chosen to allow the compound to be Cs-symmetric or pseudo Cs-symmetric.

10. The lubricating oil composition of claim 1, wherein the precatalyst compound comprises di(para-triethylsilylphenyl)methylene(2,7-di-tertbutyl fluorenyl)(cyclopentadienyl)zirconium dimethyl.

11. The lubricating oil composition of claim 1, wherein the activator comprises one or more of N,N-dimethylanilinium tetra(pentafluorophenyl)borate, N,N-dialkylphenylanilinium tetra(pentafluorophenyl)borate where the alkyl is a C1 to C18 alkyl group, trityl tetra(pentafluorophenyl)borate, tris(pentafluorophenyl)boron, tri-alkylammonium tetra(pentafluorophenyl)borate where the alkyl is a C1 to C18 alkyl group, tetra-alkylammonium tetra(pentafluorophenyl)borate where the alkyl is a C1 to C18 alkyl group.

12. The lubricating oil composition of claim 1, wherein the molecular weight distribution (Mw/Mn) of 1.0 to 2.5.

13. The lubricating oil composition of claim 1, wherein the polymer contains at least 60 mol % of units derived from propylene.

14. The lubricating oil composition of claim 1, wherein the lubricating oil composition has a kinematic viscosity at 40 C., as measured by ASTM D445-3, of less than 500 cSt.

15. The lubricating oil composition of claim 1, wherein the lubricating oil composition has a kinematic viscosity at 100 C., as measured by ASTM D445-5, of less than 50 cSt.

16. The lubricating oil composition of claim 1, wherein the lubricating oil composition has a kinematic viscosity at 100 C., as measured by ASTM D445-5, of greater than 10 cSt to less than 40 cSt.

Description

EXAMPLES

(1) The following examples are for purposes of illustration only and are non-limiting examples.

(2) Preparation of Syndiotactic Propylene-Hexene Polymers

(3) Syndiotactic propylene-hexene polymers were made using the polymerization conditions listed in Table 1. The polymerization reaction was carried out under nitrogen (N.sub.2) inert atmosphere. All solutions were prepared using purified toluene as solvent. Propylene and 1-hexene were separately feed into reactor. The catalysts used in Examples 1 to 3 and Comparative Example 1 were di(para-triethylsilylphenyl)methylene(2,7-di-tertbutyl fluorenyl)(cyclopentadienyl)zirconium dimethyl (Zr-CAT) and di(para-triethylsilylphenyl)(methylene(2,7-di-tertbutyl fluorenyl)(cyclopentadienyl)hafnium dimethyl (Hf-CAT), respectively. N,N-dimethylanilinium tetrakis(pentafluorophenyl) borate was used as activator. Tri-n-octyl-aluminum (TNOA) and hydrogen were also fed. The MFR of the resulting polymers were tested and results are shown in Table 1.

(4) ##STR00015##

(5) TABLE-US-00001 TABLE 1 Preparation of Syndiotactic Propylene-Hexene Copolymers Example Example Example Comparative 1 2 3 Example 1 Reactor volume 0.5 0.5 0.5 1 (liter) Reaction 50 50 50 50 Temperature ( C.) Reaction Pressure 320 320 320 320 (psig) Agitator (rpm) 1500 1500 1500 1500 Isohexane feed 32.5 32.5 35.3 65 (g/min) Propylene feed 5.0 5.0 5.0 10.0 (g/min) 1-hexene feed 1.54 1.54 1.54 13.46 (g/min) Catalyst Zr-CAT Zr-CAT Zr-CAT Hf-CAT Catalyst feed 1.102 1.102 1.47 4.497 (mol/min *10.sup.7) Activator feed 1.125 1.125 1.5 4.589 (mol/min *10.sup.7) TNOA feed 5.16 5.16 10.3 10.3 (mol/min *10.sup.6) Net H.sub.2 feed (sccm) 2.41 2.41 0.242 2.39 H.sub.2 feed conc (tank) 24.1 24.1 2.0 23.9 Polyrate (reactor, 0.29 0.18 1.80 9.40 g/min) Cement % 1.1 0.9 5.3 14.6 (calculated) Activity (Rxr) (g/g) 3019 1853 14318 22877 Yield (g) 17.1 10.5 72.1 97.1 MFR (230 C., 2.8 3.2 8.1 2.56 2.16 kg)
Preparation of Lubricating Oil

(6) Lubricating oils were prepared using Jurong150, a Group II base oil, available from Exxon Mobil Corporation, and different polymers as VI improvers. In Comparative Examples C2 to C8, SV140 and SV150 are styrene-diene block copolymers and SV260 and SV300 are styrene-diene star shaped copolymers, all commercially available from Infineum Chemical Company, Viscoplex 12-320 and 8-219 available from Evonik Oil Additives USA, Inc., and Lubrizol 7773 available from The Lubrizol Corporation were used. In Comparative Example C9, the syndiotactic propylene-hexene polymer prepared in Comparative Example C1 above was used. In Comparative Examples C10 to C12, syndiotactic propylene-hexene polymers having unmeasurable fractional melt flow rates were used. In Examples 4 to 6, the syndiotactic propylene-hexene polymers respectively prepared in the above Examples 1 to 3 were used.

(7) The lubricating oil compositions contained Irganox 1076 phenolic antioxidant available from BASF Corporation, Irgafos 168 phosphite antioxidant available from BASF Corporation, and 1.0 gram of the above VI improvers, dissolved in 98.98 grams of a Group II base oil to make up a total of 100 grams of polymer solution. The solution was then heated up to 140 C. for a short period of time (<1 hr.) to ensure all solids dissolved. The formulations for each Comparative Example and Example are shown in Table 2

(8) Kinematic viscosities, thickening efficiency (TE), viscosity index (VI), and shear stability index (SSI) were tested with 1 wt % of the solution as samples, with the results shown in Table 2.

(9) Thickening efficiency was calculated from Kinematic viscosity at 100 C. as measured by ASTM D445-5, as follows:
TE=2(log Blog R)/M*log 2
wherein R is the viscosity of the base oil, B is the viscosity of the polymer solution prepared, and M is the mass of polymer in solution (gms of polymer/100 gms of base oil).

(10) Shear stability index was measured at 30 cycles (ASTM D6278) and 90 cycles (ASTM D7109) using a Kurt Orbahn (KO) diesel injection apparatus.

(11) As seen from the results in Table 2, the lubricating oils of Examples 4 to 6 that comprised the syndiotactic propylene-hexene polymers made in the Examples 1 to 3 showed a better balance of high thickening efficiency with acceptable shear stability index, as compared with Comparative Examples C2 to C12, which comprised non-syndiotactic propylene--olefin polymers or syndiotactic propylene--olefin polymers having unmeasurable melt flow rate. Therefore, the syndiotactic propylene--olefin polymers described herein can be used as a high performance viscosity index improver.

(12) TABLE-US-00002 TABLE 2 Lubricating Oil Compositions Example No. C2 C3 C4 C5 C6 C7 C8 4 5 6 C9 C10 C11 C12 Jurong 150 98.98 98.98 98.98 98.98 98.98 98.98 98.98 98.98 98.98 98.98 98.98 98.98 98.98 98.98 Irganox 1076 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 Irgafos 168 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 (Irganox L180) SV 140 1 SV 150 1 SV 260 1 SV 300 1 Viscoplex 1 12-320 Viscoplex 1 8-219 Lubrizol 7773 1 sPP MFR = 8.1 1 sPP MFR = 3.2 1 sPP MFR = 2.8 1 sPP MFR = 1 2.56 sPP MFR = 1 fractional sPP MFR = 1 fractional sPP MFR = 1 fractional Properties KV 40 92.00 54.32 74.20 92.00 31.15 31.07 31.05 71.53 76.79 82.83 92.93 396.50 511.90 TVTM (H445-3) (cSt) KV 100 15.69 10.2 12.31 14.51 5.6 5.61 5.59 11.67 12.46 13.33 15.30 55.96 75.26 155.50 (H445-5) (cSt) VI 182 179 164 164 119 120 119 158 161 163 174 210 229 NA Thickening 3.1 1.86 2.4 2.9 0.13 0.13 0.12 2.24 2.43 2.63 3.03 6.77 7.62 9.72 Efficiency (TE) Shear Stability 45 7.7 19.2 51.3 0.7 0.2 0.5 37.2 47.3 51.5 67.1 92.1 95 97.1 Index (30 cycles) Shear Stability 72 17.8 42.2 63.9 0.7 0.3 0.6 41.5 51.3 55.4 70.5 93 95.6 97.5 Index (90 cycles) TVTM = too viscous to measure.

(13) All patents and patent applications, test procedures (such as ASTM methods, UL methods, and the like), and other documents cited herein are fully incorporated by reference to the extent such disclosure is not inconsistent with this invention and for all jurisdictions in which such incorporation is permitted.

(14) When numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated. While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which the invention pertains.