Elastic diene terpolymer and preparation method thereof

Abstract

The present invention relates to a long-chain branched elastic terpolymer capable of satisfying excellent processability and elasticity (flexibility) at the same time, which is obtained in the presence of a Group IV transition metal catalyst, and a preparation method thereof. The elastic terpolymer is a copolymer of ethylene, an alpha-olefin having 3 to 20 carbon atoms, and a diene, wherein i) its weight average molecular weight measured by GPC is 100,000 to 500,000, and ii) x which is the ethylene content (% by weight) and y which is the density value (g/cm.sup.3) of the copolymer measured when the ethylene content is X satisfy a relationship of 0.0000175214x(x75.65420571)+0.875y0.0000175214x(x75.65420571)+0.881.

Claims

1. An elastic terpolymer, wherein the elastic terpolymer is a copolymer of ethylene, an alpha-olefin having 3 to 20 carbon atoms, and a diene, obtained in the presence of a Group IV transition metal catalyst, wherein i) its weight average molecular weight measured by GPC is 100,000 to 500,000, and ii) x which is an ethylene content (% by weight) and y which is a density value (g/cm.sup.3) of the copolymer measured when the ethylene content is X satisfy a relationship of 0.0000175214x(x75.65420571)+0.875y0.0000175214x(x75.65420571)+0.881.

2. The elastic terpolymer of claim 1, wherein an LCB Index which is a ratio of 1.sup.st harmonics of storage modulus to 5.sup.th harmonics of storage modulus measured at 125 C. using a rubber process analyzer according to a LAOS (Large Angles of Oscillation and high Strains) method has a positive value.

3. The elastic terpolymer of claim 2, wherein the LCB Index is more than 0 and 5 or less.

4. The elastic terpolymer of claim 1, wherein Re*Rc is less than 1, in which Re*Rc is a product of a reactivity ratio Re representing the distribution of ethylene in the copolymer and a reactivity ratio Rc representing the distribution of alpha-olefin in the copolymer, and Re=k11/k12 and Rc=k22/k21, wherein k11 is a growth reaction rate constant when ethylene binds next to ethylene in the copolymer chain, k12 is a growth reaction rate constant when alpha-olefin binds next to ethylene in the copolymer chain, k21 is a growth reaction rate constant when ethylene binds next to alpha-olefin in the copolymer chain, and k22 is a growth reaction rate constant when alpha-olefin binds next to alpha-olefin in the copolymer chain.

5. The elastic terpolymer of claim 4, wherein, Re*Rc is 0.60 to 0.99.

6. The elastic terpolymer of claim 1, wherein the copolymer of ethylene, the alpha-olefin having 3 to 20 carbon atoms, and the diene is a copolymer of 40 to 80% by weight of ethylene, 15 to 55% by weight of the alpha-olefin having 3 to 20 carbon atoms, and 4 to 6% by weight of the diene.

7. The elastic terpolymer of claim 1, wherein the elastic terpolymer has a density of 0.840 to 0.895 g/cm.sup.3.

8. The elastic terpolymer of claim 1, wherein the elastic terpolymer has Mooney viscosity (1+4{circle around (a)}125 C.) of 5 to 180.

9. The elastic terpolymer of claim 1, wherein the elastic terpolymer has a molecular weight distribution of 2 to 4.

10. The elastic terpolymer of claim 1, wherein the alpha-olefin is one or more selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene, and the diene is one or more selected from the group consisting of 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, and 4-hexadiene.

11. A method for preparing the elastic terpolymer of claim 1, comprising the step of continuously feeding a monomer composition containing 40 to 80% by weight of ethylene, 15 to 55% by weight of the alpha-olefin having 3 to 20 carbon atoms, and 4 to 6% by weight of the diene to a reactor to perform copolymerization in the presence of a catalytic composition including a first transition metal compound represented by the following Chemical Formula 1 and a second transition metal compound represented by the following Chemical Formula 2: ##STR00007## wherein R.sub.1 to R.sub.13 are the same as or different from each other, and are each independently hydrogen, an alkyl radical having 1 to 20 carbon atoms, an alkenyl radical having 2 to 20 carbon atoms, an aryl radical having 6 to 20 carbon atoms, a silyl radical, an alkylaryl radical having 7 to 20 carbon atoms, an arylalkyl radical having 7 to 20 carbon atoms, or a hydrocarbyl-substituted metalloid radical of a Group IV metal; of R.sub.1 to R.sub.13, two different neighboring groups are connected to each other by an alkylidine radical containing an alkyl having 1 to 20 carbon atoms or an aryl radical having 6 to 20 carbon atoms to form an aliphatic or aromatic ring; M is a Group IV transition metal; and Q.sub.1 and Q.sub.2 are the same as or different from each other, and are each independently a halogen radical, an alkyl radical having 1 to 20 carbon atoms, an alkenyl radical having 2 to 20 carbon atoms, an aryl radical having 6 to 20 carbon atoms, an alkylaryl radical having 7 to 20 carbon atoms, an arylalkyl radical having 7 to 20 carbon atoms, an alkylamido radical having 1 to 20 carbon atoms, an arylamido radical having 6 to 20 carbon atoms, or an alkylidene radical having 1 to 20 carbon atoms.

12. The method of claim 11, wherein the first transition metal compound is one or more selected from the group consisting of the following compounds: ##STR00008## wherein R.sub.2 and R.sub.3 are the same as or different from each other and are each independently hydrogen or a methyl radical, M is a Group IV transition metal, and Q.sub.1 and Q.sub.2 are the same as or different from each other and are each independently a methyl radical, a dimethylimido radical, or a chlorine radical.

13. The method of claim 11, wherein the second transition metal compound is one or more selected from the group consisting of the following compounds: ##STR00009## wherein R.sub.2 and R.sub.3 are the same as or different from each other and are each independently hydrogen or a methyl radical, M is a Group IV transition metal, and Q.sub.1 and Q.sub.2 are the same as or different from each other and are each independently a methyl radical, a dimethylimido radical, or a chlorine radical.

14. The method of claim 11, wherein the catalytic composition further includes one or more co-catalytic compounds selected from the group consisting of the following Chemical Formula 3, Chemical Formula 4, and Chemical Formula 5:
[Al(R)O].sub.n[Chemical Formula 3] wherein R's are the same as or different from each other and are each independently a halogen, a hydrocarbon having 1 to 20 carbon atoms, or a halogen-substituted hydrocarbon having 1 to 20 carbon atoms, and n is an integer of 2 or more;
D(R).sub.3[Chemical Formula 4] wherein R is the same as defined in Chemical Formula 3, and D is aluminum or boron; and
[L-H].sup.+[ZA.sub.4].sup. or [L].sup.+[ZA.sub.4].sup.[Chemical Formula 5] wherein L is a neutral or cationic Lewis acid, H is a hydrogen atom, Z is an element of Group 13, and A's are the same as or different from each other and are each independently an aryl group having 6 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms, in which one or more hydrogen atoms are unsubstituted or substituted with a halogen, a hydrocarbon having 1 to 20 carbon atoms, an alkoxy, or a phenoxy.

15. The method of claim 11, wherein the alpha-olefin is one or more selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene, and the diene is one or more selected from the group consisting of 5-ethylidene-2-norbornene, 5-methylene-2-norbomene, and 4-hexadiene.

16. The method of claim 11, wherein copolymerization is performed while continuously feeding the monomer composition, the first and second transition metal compounds, and the co-catalyst in a solution state to a reactor.

17. The method of claim 16, wherein the copolymerization step is continuously performed while continuously discharging the copolymerized elastic terpolymer from the reactor.

18. The method of claim 11, wherein the copolymerization step is performed at a temperature of 100 to 170 C.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The FIGURE is a graph showing the relationship between the ethylene content and the density for elastic terpolymers prepared in examples and comparative examples.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) The present invention will be described in more detail in the following examples. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

(3) <Synthesis of Ligand and Transition Metal Compound>

(4) Synthesis of all ligands and catalysts was performed by standard Schlenk and glovebox techniques under a nitrogen atmosphere to avoid contact with air and moisture, and organic reagents and solvents used in reactions were purchased from Sigma-Aldrich and Merck, and purified by a standard method before use. The structures of the synthesized ligands and catalysts were confirmed by 400 MHz Nuclear Magnetic Resonance (NMR) Spectroscopy and X-ray Spectroscopy.

(5) In the following examples, as first and second transition metal compounds, [(1,2,3,4-tetrahydroquinolin-8-yl)tetramethylcyclopentadienyl-eta5,kapa-N]titanium dimethyl and [(2-methylindolin-7-yl)tetramethylcyclopentadienyl-eta5,kapa-N]titanium dimethyl were used, respectively. As a co-catalytic compound, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate and triisobutylaluminum were used. The first and second transition metal compounds were prepared and used in the same manner as in Examples 2 and 14 of Korean Patent No. 0,976,131, and the co-catalytic compound was prepared and used in the same manner as in Example 9 of Korean Patent No. 0,820,542.

Preparation of Elastic Terpolymer of Ethylene, Propylene, and 5-Ethylidene-2-Norbornene

(6) Terpolymerization of ethylene, propylene, and 5-ethylidene-2-norbornene was continuously performed using a 2 L-pressure reactor. Hexane as a polymerization solvent was continuously fed to the bottom of the reactor at a feed rate of 7.6 kg per hour, and the polymerization solution was continuously discharged from the top of the reactor.

(7) As the first and second transition metal compounds, the above-described [(1,2,3,4-tetrahydroquinolin-8-yl)tetramethylcyclopentadienyl-eta5,kapa-N]titanium dimethyl and [(2-methylindolin-7-yl)tetramethylcyclopentadienyl-eta5,kapa-N]titanium dimethyl dissolved in hexane were used, and fed to the reactor at a rate of 51 to 54 mol per hour. Further, as the co-catalytic compound, the above-described N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate dissolved in toluene was used, and fed to the reactor at a rate of 255 to 270 mol per hour. Further, as the additional co-catalytic compound, the above described triisobutylaluminum dissolved in hexane was used, and fed to the reactor at a rate of 4080 to 4200 mol per hour.

(8) As the monomers, ethylene at a rate of 950 g per hour, propylene at a rate of 820 to 950 g per hour, and 5-ethylidene-2-norbornene at a rate of 86 to 129 g per hour were continuously fed to the reactor to perform the copolymerization.

(9) The copolymerization temperature in the reactor was controlled between 120 to 140 C. while 0.5 mL/min of the feed rate of 5-ethylidene-2-norbornene was increased from 1 mL/min at around 140 C.

(10) Under the above-described conditions, copolymerization was performed by continuous solution polymerization to prepare elastic terpolymers of Examples 1 to 7 in the form of homogeneous solution in a continuous manner, and the polymerization solutions continuously discharged from the top of the reactor were dried under reduced pressure in a 60 C. vacuum oven after termination of the polymerization reaction under ethanol, and finally, copolymers of Examples 1 to 7 were prepared.

Commercialized Elastic Terpolymer of Ethylene, Propylene, and 5-Ethylidene-2-Norbornene

(11) 4520, 4640, 4760, and 4770 of DOW, which are commercialized EPDM rubber known to be prepared by the metallocene catalyst, were used as elastic terpolymers of Comparative Examples 14, respectively.

(12) The content of each monomer in the copolymers thus obtained is the same as summarized in the following Table 1. In this regard, the content of each monomer was measured using Bruker 600 MHz Avance III HD NMR. At this time, the temperature was 373 K and an ODCB-d4 solution was used for .sup.1H NMR measurement of the samples.

(13) TABLE-US-00001 TABLE 1 5-ethylidene-2- Ethylene Propylene norbornene wt % wt % wt % Example 1 52.1 43.2 4.7 Example 2 52.7 42.2 5.1 Example 3 53.9 41.3 4.8 Example 4 56.9 38.4 4.7 Example 5 62.8 29.9 5.1 Example 6 65.0 29.9 5.1 Example 7 70.0 25.1 4.9 Comparative 47.1 47.3 5.6 Example 1 Comparative 51.2 43.6 5.2 Example 2 Comparative 65.0 30.1 4.9 Example 3 Comparative 69.9 25.0 5.1 Example 4

Measurement of Density, and Derivation of Relationship Between Ethylene Content and Density

(14) Density data of the copolymers of examples and comparative examples was obtained using a density meter of METTLER TOLEDO XS 104, and the density was measured by a Hydrostatic Method of the density measurement methods according to ASTM D297. More specifically, the temperature of water was measured to obtain a density of water, and then the weight of the sample was measured in air and water, respectively. A holder was used for measuring the weight of the sample floating in water, and density was calculated by the following Equation 1.
Density[g/cm.sup.3]=D*A/{A(BC)}[Equation 1]

(15) A=weight of sample in air [g]

(16) B=weight of sample and weight of holder in water [g]

(17) C=weight of holder in water [g]

(18) D=density of water

(19) The density values of the examples and comparative examples thus obtained are shown in Table 2. Data for each copolymer is presented by plotting the content of ethylene included in each copolymer of the examples on the x axis, and the density of each copolymer on the y axis, and then linear regression is applied to the data so as to derive the relationship between the ethylene content, x, and the density, y. This relationship is shown as in the FIGURE, and for comparison with the examples, data of Comparative Examples 1 and 4 are also shown in the FIGURE.

Measurement of LCB Index

(20) Behaviors of shear storage modulus of the copolymers obtained in the examples and comparative examples were measured using a SIS V-50 rubber process analyzer of SCARABAEUS INSTRUMENTS SYSTEMS at a predetermined temperature (125 C.) and frequency (0.2 Hz) while varying strain from 0.2% to 1250%. The measured storage modulus was converted into FT to derive 1.sup.st harmonics and 5.sup.th harmonics, and then a ratio of the 1.sup.st harmonics of storage modulus to 5.sup.th harmonics of storage modulus was calculated as the LCB Index, and shown in the following Table 2.

(21) In this regard, when 1.sup.st harmonics and 5.sup.th harmonics of the measured storage modulus are defined as G.sub.1 and G.sub.5, respectively, the LCB Index can be expressed as the following Equation 2.
LCB Index=G.sub.1/G.sub.5[Equation 2]

Measurement of Re*Rc

(22) Each copolymer of the examples and comparative examples was analyzed by .sup.13C-NMR to obtain a growth reaction rate constant of k11, k12, k21, or k22. In this regard, a 600 MHz Bruker DRX 600 instrument was used for measurement, and each copolymer dissolved in ortho-dichlorobenzene-d4 solution was analyzed at 100 C.

(23) Each growth reaction rate constant can be obtained from the results of .sup.13C-NMR analysis by Triad Sequence analysis according to the Randall method [Journal of Polymer Science: Polymer Physics edition, 1973, 11, 275287] and the Kakugo method [Macromolecules 1982, 15, 1150]. Based on the equations of Re=k11/k12 and Rc=k22/k21, the Re*Rc value was calculated.

(24) The Re*Rc value of each copolymer is also shown in the following Table 2.

(25) TABLE-US-00002 TABLE 2 Content of ethylene Density wt % g/cm3 LCB Index Re*Rc Example 1 52.1 0.857 1.55 0.573 Example 2 52.7 0.858 1.33 0.642 Example 3 53.9 0.859 0.80 0.631 Example 4 56.9 0.858 0.29 0.713 Example 5 62.8 0.862 0.94 0.770 Example 6 65.0 0.865 0.78 0.843 Example 7 70.0 0.870 0.82 0.942 Comparative 47.1 0.859 1.69 1.608 Example 1 Comparative 51.2 0.860 1.23 1.449 Example 2 Comparative 65.0 0.871 1.13 1.458 Example 3 Comparative 69.9 0.876 1.10 1.516 Example 4

(26) Referring to Table 2 and the FIGURE, the copolymers of Examples 1 to 7 showed that the ethylene content x and the density y satisfied the relationship of 0.0000175214x(x75.65420571)+0.875y0.0000175214x(x75.65420571)+0.881, the LCB Index had a positive value, and Re*Rc was less than 1.

(27) In contrast, the copolymers of Comparative Examples 1 to 4 showed that the copolymers having the ethylene content similar to those of the examples exhibited higher density so as to not satisfy the relationship of 0.0000175214x(x75.65420571)+0.875y0.0000175214x(x75.65420571)+0.881, the LCB Index had a negative value, and Re*Rc was greater than 1.

(28) These results suggest that the elastic terpolymers of Examples 1 to 7 show a uniform alternate distribution of monomers in the polymer chains, thereby having low density with respect to the ethylene content, and superior low-temperature properties, elasticity, and flexibility to those of the comparative examples.