Alphaolefin oligomer having uniform structure and method of preparing same

Abstract

The present invention relates to an alphaolefin oligomer having a uniform structure and a method of preparing the same, in which the alphaolefin oligomer has a uniform molecular structure with a low branch ratio, thereby exhibiting improved thermal and oxidative stability, a long service life, low volatility, a low pour point and a high viscosity index.

Claims

1. A hydrogenated alphaolefin oligomer composition comprising at least one hydrogenated alphaolefin oligomer, the at least one hydrogenated alphaolefin oligomer having a molecular structure with a weight average molecular weight of 697 to 1300 and having a branch ratio of 0.265 or less as represented by Equation (1) below
Branch ratio=P1/P2  (1) wherein P1 is an amount of a CH.sub.3 group and P2 is an amount of a CH.sub.2 group, the amount of the CH.sub.2 group and the amount of the CH.sub.3 group being measured through .sup.1H-NMR, wherein the at least one hydrogenated alphaolefin oligomer has a kinematica viscosity at 100° C. of 6.3 cSt or less and has a viscosity index of 134.1 or more.

2. The hydrogenated alphaolefin oligomer composition of claim 1, wherein the at least one hydrogenated alphaolefin oligomer is configured such that carbon at position B2 in Structural Formula 1 below has a T.sub.1 relaxation time of less than 0.6 at 298 K as measured by an NMR pulse sequence ##STR00005## wherein n=1 to 9.

3. The hydrogenated alphaolefin oligomer composition of claim 2, wherein carbon at position B3 of the at least one hydrogenated alphaolefin oligomer has a T.sub.1 relaxation time of less than 0.5 at 298 K as measured by the NMR pulse sequence.

4. The hydrogenated alphaolefin oligomer composition of claim 2, wherein carbon at position B3 of the at least one hydrogenated alphaolefin oligomer is tertiary carbon (CH group) or secondary carbon (CH.sub.2 group).

5. The hydrogenated alphaolefin oligomer composition of claim 2, wherein carbon at position A1 of the at least one hydrogenated alphaolefin oligomer has a T.sub.1 relaxation time of 2.35 or more at 298 K as measured by the NMR pulse sequence.

6. The hydrogenated alphaolefin oligomer composition of claim 2, wherein carbon at position A2 of the at least one hydrogenated alphaolefin oligomer has a T.sub.1 relaxation time of 2.20 or more at 298 K as measured by the NMR pulse sequence.

7. The hydrogenated alphaolefin oligomer composition of claim 1, wherein the at least one hydrogenated alphaolefin oligomer has a flash point of 235° C. or more.

8. The hydrogenated alphaolefin oligomer composition of claim 1, wherein the at least one hydrogenated alphaolefin oligomer has a Noack volatility of less than 12%.

9. The hydrogenated alphaolefin oligomer composition of claim 1, wherein the at least one hydrogenated alphaolefin oligomer has a pour point of −50° C. or less.

10. The hydrogenated alphaolefin oligomer composition of claim 1, wherein the at least one hydrogenated alphaolefin oligomer has a kinematic viscosity at 100° C. of 6.3 cSt or less.

11. The hydrogenated alphaolefin oligomer composition of claim 1, wherein the at least one hydrogenated alphaolefin oligomer has a kinematic viscosity at 40° C. of 35.0 cSt or less.

12. The hydrogenated alphaolefin oligomer composition of claim 1, wherein the at least one hydrogenated alphaolefin oligomer contains 0.1 to 3.5 wt % of a dimer.

13. A lubricant composition comprising the hydrogenated alphaolefin oligomer composition of claim 11.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a graph showing the carbon NMR spectrum of a decene oligomer polymerized using a metallocene catalyst;

(2) FIG. 2 is a graph showing the T1 inversion recovery power gated (T1IRPG) decoupling 2D experiment spectrum of a decene oligomer polymerized using the metallocene catalyst of Example 1; and

(3) FIG. 3 is a graph showing the T1IRPG decoupling 2D experiment spectrum of a decene oligomer polymerized using the cation catalyst of Comparative Example 1.

DESCRIPTION OF SPECIFIC EMBODIMENTS

(4) Hereinafter, a detailed description will be given of the preferred embodiments of the present invention. However, the present invention is not limited to these embodiments, but may be modified in other forms. These embodiments are provided in order to fully convey the spirit of the present invention to those skilled in the art so that the contents introduced herein are thorough and complete.

Example 1: Preparation of Oligomer Using Metallocene Catalyst—Simple Distillation and then Hydrogenation

(5) 1. Oligomerization

(6) 530 ml (392 g) of decene was placed in a 1 L stainless steel autoclave reactor and then maintained at 110° C. In this procedure, as necessary, the polymerization temperature was adjusted to the range of 50 to 150° C., and 1 mmol of triisobutylaluminum was added, or was not added if not needed. Thereafter, the already prepared catalyst (including 0.01 mmol of a metallocene catalyst, 0.012 mmol of a promoter, 0.6 mmol of triisobutylaluminum and 6 ml of toluene) was placed in the reactor. Subsequently, the reaction was carried out for 3 hr with stirring at 700 rpm, after which the reaction was terminated by the addition of 400 ml of a 10% sodium hydroxide aqueous solution. Next, the upper organic layer was extracted, and unreacted decene and decene isomers as byproducts were stripped and removed, thereby obtaining a decene oligomer.

(7) 2. Simple Distillation of Oligomer

(8) 150 ml of the decene oligomer prepared above was placed in a 2 L flask with a 5-30 cm Vigreux distillation column and was then maintained in a vacuum to remove oxygen. Thereafter, vacuum distillation was conducted at a pressure of 0.45 torr and a temperature of 170 to 230° C., after which the residue was cooled to room temperature in a vacuum in order to prevent pyrolysis thereof.

(9) 3. Hydrogenation of Oligomer

(10) 140 g of 5 wt % palladium/alumina was placed in a 1 L Parr reactor, and 0.5 L of the decene oligomer separated above was added thereto and purged with nitrogen at 120° C. for 30 min. Thereafter, the temperature was elevated to 180° C. and the reaction was initiated under a hydrogen pressure of 2 MPa and was then terminated after 4 hr.

Example 2: Preparation of Oligomer Using Metallocene Catalyst—Hydrogenation and then Simple Distillation

(11) 1. Oligomerization

(12) 100 wt % of hexane was placed in a 1 L stainless steel autoclave reactor and then maintained at 110° C. In this procedure, as necessary, the polymerization temperature and the amount of added hexane were adjusted to 50-150° C. and 0-100 wt %, respectively. Thereafter, the already prepared catalyst (including 0.4 mmol of a metallocene catalyst, 0.5 mmol of a promoter, 1.1 mmol of triisobutylaluminum and 350 ml of toluene) was placed at 0.2-0.3 ml/min in the reactor, and simultaneously, decene was added at 5.0-7.0 ml/min. Subsequently, the reaction was carried out for 3 hr with stirring at 1200 rpm, after which the reaction was terminated by the addition of 400 ml of a 10% sodium hydroxide aqueous solution. Next, the upper organic layer was extracted, and unreacted decene and decene isomers as byproducts were stripped and removed, thereby obtaining a decene oligomer.

(13) 2. Hydrogenation and Simple Distillation of Oligomer

(14) The same procedures as in Example 1 were performed, with the exception that the prepared oligomer was first hydrogenated and then subjected to simple distillation, unlike Example 1.

Example 3: Preparation of Oligomer Using Metallocene Catalyst—Hydrogenation and then Simple Distillation

(15) 1. Oligomerization

(16) The oligomerization was performed in the same manner as in Example 2.

(17) 2. Hydrogenation and Simple Distillation of Oligomer

(18) The same procedures as in Example 2 were performed, with the exception that vacuum distillation was conducted at a pressure of 0.45 torr and a temperature of 260 to 290° C. upon simple distillation of the oligomer, unlike Example 2.

Comparative Example 1: Preparation of Oligomer Using Cation Catalyst—Simple Distillation and then Hydrogenation

(19) A decene oligomer was prepared using a cation catalyst, unlike the above Examples.

(20) Specifically, 135 ml (100 g) of decene was placed in a 1 L stainless steel autoclave reactor and the polymerization temperature was then maintained at 10 to 20° C. Subsequently, a cation catalyst (ACl.sub.3, BF.sub.3, etc.) complexed with an alcohol was added at 0.8 mmol/100 g into the reactor. Thereafter, the reaction was carried out for 2 hr in a nitrogen atmosphere with stirring at 700 rpm, after which the reaction was terminated by the addition of dilute ammonium hydroxide at a temperature of 80 to 90° C. Then, the upper organic layer was extracted, and unreacted decene and decene isomers as byproducts were stripped and removed, thereby obtaining a decene oligomer. The simple distillation of the prepared oligomer and the hydrogenation of the decene oligomer were performed in the same manner as in Example 1, with the exception that vacuum distillation was conducted at a temperature of 160 to 220° C. upon simple distillation.

Comparative Example 2: Preparation of Oligomer Using Cation Catalyst—Hydrogenation and then Simple Distillation

(21) An oligomer was prepared in the same manner as in Comparative Example 1, after which the prepared oligomer was subjected to hydrogenation and then simple distillation, unlike Comparative Example 1.

(22) Evaluation of Properties

(23) The properties of the alphaolefin oligomers prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were measured as follows.

(24) 1. Measurement of Molecular Weight

(25) The molecular weights of the oligomers of Examples 1 to 3 and Comparative Examples 1 and 2 were measured through gel permeation chromatography (GPC). The results are shown in Table 1 below.

(26) TABLE-US-00001 TABLE 1 Mn Mw Mz Mw/Mn Example 1 702 725 752 1.033 Example 2 665 697 740 1.049 Example 3 900 936 972 1.040 Comparative Example 1 666 691 720 1.037 Comparative Example 2 625 650 679 1.039

(27) 2. Measurement of Viscosity Index, Pour Point, Flash Point and Noack Volatility

(28) The VI (viscosity index; ASTM D445), pour point (ASTM D97), flash point (ASTM D92), bromine number and Noack volatility (ASTM D5800) of the alphaolefin oligomers of Examples 1 to 3 and Comparative Examples 1 and 2 were measured. The results are shown in Table 2 below.

(29) TABLE-US-00002 TABLE 2 Ex- Ex- Ex- Compar- Compar- ample ample ample ative ative 1 2 3 Example 1 Example 2 Viscosity @100° C. 3.90 4.06 6.01 4.13 4.06 (cSt) Viscosity @40° C. 16.54 17.41 30.54 18.50 17.82 Viscosity Index 134.1 136.1 147.2 127.3 129.7 Pour point (° C.) −72 −75 −75 −74 −72 Flash point (° C.) 240 242 248 234 230 Noack vol. (%) 11.31 10.15 6.73 12.88 13.71 Bromine No. 0.25 0.18 0.26 0.57 0.24 (g/100 g)

(30) As is apparent from Table 2, the properties of the alphaolefin oligomers of Examples were superior to those of the alphaolefin oligomers of Comparative Examples, which is deemed to be due to the difference in the molecular structure of the alphaolefin formed during the polymerization.

(31) Specifically, the oligomers prepared in Examples had a uniform molecular structure with a low branch ratio, containing no tertiary hydrogen due to isomerization, and were thus improved in properties such as viscosity index, flash point, pour point and Noack volatility.

(32) 3. Measurement of T.sub.1 Relaxation Time

(33) Using 500 MHz NMR (Bruker AVANCE III) with a BBO probe, the T.sub.1 relaxation time at 298 K of the oligomers of Examples 1 to 3 and Comparative Examples 1 and 2 was measured. Specifically, 0.1 g of a decene oligomer and 1 ml of a deuterium solvent (chloroform) were placed in an NMR tube, after which measurement was performed through hydrogen and carbon NMR spectra, DEPT (Distortion-less Enhanced by Polarization Transfer), COSY (Correlation Spectroscopy), HSQC (Heteronuclear Single-Quantum Correlation Spectroscopy) and HMBC (Heteronuclear Multiple-Bond Correlation Spectroscopy). The spectral results were analyzed and the carbon peak for each structure is shown in Table 3 below, and the measured T.sub.1 relaxation time is shown in Table 4 below.

(34) Moreover, the T.sub.1 relaxation time measurement spectrum of the alphaolefin oligomer of Example 1 is shown in FIG. 2, and the T.sub.1 relaxation time measurement spectrum of the alphaolefin oligomer of Comparative Example 1 is shown in FIG. 3. Here, the spectral results were obtained using pulse sequences of T1IRPG (T1 Inversion Recovery Power Gated) decoupling 2D experiment, and τ (the time between 1800 pulse and 900 pulse) is 0.3 to 1.0 sec and 1.5 to 2.0 sec (0.1 second interval).

(35) TABLE-US-00003 TABLE 3 Carbon Peak (ppm) Posi- Example Example Example C. Example C. Example tion Kind 1 2 3 1 2 A1 CH.sub.3 14-15 14-15 14-15 14-15 14-15 A2 CH.sub.2 22-24 22-24 22-24 22-24 22-24 B1 CH.sub.3 19-21 19-21 19-21 16-17 16-17 B2 CH 34-35 34-35 34-35 34-35 34-35 B3 CH.sub.2 42-43 42-43 42-43 40-43 40-43

(36) TABLE-US-00004 TABLE 4 T1 Ex- Ex- Ex- Compar- Compar- Relaxation ample ample ample ative ative time 1 2 3 Example 1 Example 2 A1 2.54 2.54 2.46 2.25 2.32 A2 2.32 2.32 2.25 2.17 2.17 B1 0.94 0.94 0.72 1.01 1.01 B2 0.50 0.50 0.36 0.65 0.65 B3 0.29 0,29 0.29 0.65 0.65

(37) As is apparent from Tables 3 and 4, based on the results of measurement of T.sub.1 relaxation time of the oligomers of Examples 1 to 3 and Comparative Examples 1 and 2, the results of Examples 1 to 3 were similar to those of Comparative Examples 1 and 2.

(38) Furthermore, the oligomers prepared in Examples showed higher values of the ends A1 and A2 of the terminal chain than those of the oligomers prepared in Comparative Examples, indicating that the chain is longer and the mobility of the terminal group is higher.

(39) In contrast, the oligomers prepared in Examples showed lower values of the molecular centers B1, B2 and B3 than those of the oligomers prepared in Comparative Examples, indicating that the central carbon atoms have lower mobility, that is, are more rigid.

(40) Specifically, in the oligomers having a kinematic viscosity at 100° C. of 3.7 to 4.3 cSt (Examples 1 and 2), the carbon at position B1 had a T.sub.1 relaxation time of less than 1.0, as measured by the NMR pulse sequence, and the carbons at positions B2 and B3 had a T.sub.1 relaxation time of less than 0.6. Furthermore, the carbon at position A1 had a T.sub.1 relaxation time of 2.4 or more, and the carbon at position A2 had a T.sub.1 relaxation time of 2.2 or more.

(41) In the oligomer having a kinematic viscosity at 100° C. of 5.6 to 6.4 cSt (Example 3), the carbon at position B1 had a T.sub.1 relaxation time of less than 0.85, the carbons at positions B2 and B3 had a T.sub.1 relaxation time of less than 0.55, and the carbons at positions A1 and A2 had a T.sub.1 relaxation time of 2.4 or more and a T.sub.1 relaxation time of 2.2 or more, respectively.

(42) 4. Branch Ratio

(43) As the structural properties of the alphaolefin oligomers of Examples 1 to 3 and Comparative Examples 1 and 2, the branch ratio depending on the amounts of CH.sub.2 and CH.sub.3 was measured. The results are shown in Table 5 below.

(44) The relative amounts of CH.sub.2 and CH.sub.3 were measured through hydrogen NMR, and based on 7.24 ppm of chloroform, CH.sub.2 was represented as an integral of 0.95 to 1.60 ppm, and CH.sub.3 was represented as an integral of 0.75 to 0.95 ppm. More specifically, the integral of CH.sub.3 is 1.

(45) The branch ratio is obtained by dividing the amount of the CH.sub.3 group in the molecular structure by the amount of the CH.sub.2 group, and is represented below.
Branch ratio=P1/P2  (1)

(46) (Here, P1 is the amount of CH.sub.3 group and P2 is the amount of CH.sub.2 group, the amounts of CH.sub.2 and CH.sub.3 groups being measured through .sup.1H-NMR.)

(47) TABLE-US-00005 TABLE 5 Compar- Compar- Ex- Ex- Ex- ative ative ample ample ample Example Example Regularity 1 2 3 1 2 Molar Experimental 1:4.49 1:4.28 1:4.74 1:3.62 1:3.64 Ratio value (NMR) (CH.sub.3:CH.sub.2) CH.sub.3Gr. Experimental 0.1821 0.1894 0.1742 0.2165 0.2155 (wt %) value (NMR) Branch Experimental 0.2227 0.2336 0.2109 0.2762 0.2747 Ratio value ( NMR)

(48) As is apparent from Table 5, the molar ratio of CH.sub.3 to CH.sub.2 was lower in the alphaolefin oligomers prepared in Examples than in the alphaolefin oligomers prepared in Comparative Examples, indicating that there are few branches in the molecular structure, which can also be confirmed by the branch ratio. In conclusion, as the number of branches in the molecular structure was smaller, superior oxidative stability, a high viscosity index, a lower or similar pour point and low Noack volatility were exhibited, indicative of improved properties.

(49) Although preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications are possible without departing from the scope and spirit of the invention as disclosed in the accompanying claims, and such modifications should not be understood separately from the technical ideas or essential characteristics of the present invention.