Polyethylene and chlorinated polyethylene thereof
A polyethylene according to the present disclosure maintains a stable crystal structure at a high temperature and ensures excellent uniformity in chlorine distribution, thereby preparing a chlorinated polyethylene having excellent chlorination productivity and thermal stability by reacting with chlorine, and may also prepare a PVC compound with improved impact strength by including the chlorinated polyethylene.
1. A polyethylene having an alpha transition temperature of 120° C. or more, and
a crystalline region ratio on a temperature rising elution fractionation (TREF) graph of 12.5% or less, wherein the crystalline region ratio is obtained by dividing a graph area of a crystalline region having an elution temperature or more by a total graph area in percentage, wherein the elution temperature is a splitting point corresponding to a smallest peak between two highest peaks,
wherein the polyethylene is an ethylene homopolymer.
2. The polyethylene according to claim 1 , wherein the polyethylene has the alpha transition temperature of 120° C. to 145° C.
3. The polyethylene according to claim 1 , wherein the polyethylene has the crystalline region ratio on a temperature rising elution fractionation (TREF) graph of 5% to 12.5%.
4. The polyethylene according to claim 1 , wherein the polyethylene has a melt index (MI5) of 0.1 g/10 min to 1.5 g/10 min.
5. The polyethylene according to claim 1 , wherein the polyethylene has a melt flow rate ratio (MFRR21.6/5, a value obtained by dividing the melt index measured at 190° C. under a load of 21.6 kg by the melt index measured at 190° C. under a load of 5 kg in accordance with ASTM D 1238) of 10 to 20.
6. The polyethylene according to claim 1 , wherein the polyethylene has a density of 0.947 g/cm 3 to 0.957 g/cm 3 .
7. The polyethylene according to claim 1 , wherein the polyethylene has a molecular weight distribution (Mw/Mn) of 2 to 10.
8. A method for preparing the polyethylene according to claim 1 , comprising the step of polymerizing ethylene in the presence of at least one first metallocene compound represented by Chemical Formula 1; and at least one second metallocene compound represented by Chemical Formula 2:
in Chemical Formula 1,
at least one of R 1 to R 8 is —(CH 2 ) n —OR, wherein R is C1-6 linear or branched alkyl and n is an integer of 2 to 6;
the rest of R 1 to R 8 if present are the same as or different from each other, and are each independently selected from the group consisting of hydrogen, halogen, C1-20 alkyl, C2-20 alkenyl, C6-20 aryl, C7-40 alkylaryl, and C7-40 arylalkyl, or two or more of R1 to R8 that are adjacent to each other are connected with each other to form a C6-20 aliphatic or aromatic ring unsubstituted or substituted with a C1-10 hydrocarbyl group;
Q 1 and Q 2 are the same as or different from each other, and are each independently hydrogen, halogen, C1-20 alkyl, C2-20 alkenyl, C2-20 alkoxyalkyl, C6-20 aryl, C7-40 alkylaryl, or C7-40 arylalkyl;
A 1 is carbon, silicon, or germanium;
M 1 is a Group 4 transition metal;
X 1 and X 2 are the same as or different from each other, and are each independently halogen, C1-20 alkyl, C2-20 alkenyl, C6-20 aryl, a nitro group, an amido group, C1-20 alkylsilyl, C1-20 alkoxy, or a C1-20 sulfonate group; and
m is an integer of 0 or 1,
in Chemical Formula 2,
Q 3 and Q 4 are the same as or different from each other, and are each independently hydrogen, halogen, C1-20 alkyl, C2-20 alkenyl, C2-20 alkoxyalkyl, C6-20 aryl, C7-40 alkylaryl, or C7-40 arylalkyl;
A 2 is carbon, silicon, or germanium;
M 2 is a Group 4 transition metal;
X 3 and X 4 are the same as or different from each other, and are each independently halogen, C 1-20 alkyl, C 2-20 alkenyl, C 6-20 aryl, a nitro group, an amido group, C 1-20 alkylsilyl, C 1-20 alkoxy, or a C 1-20 sulfonate group; and
one of C 1 or C 2 is represented by Chemical Formula 3a, and the other is represented by Chemical Formula 3c, 3d or 3e:
in Chemical Formulae 3a, 3c, 3d and 3e, R 9 to R 39 are the same as or different from each other, and are each independently hydrogen, halogen, C 1-20 alkyl, C 1-20 haloalkyl, C 2-20 alkenyl, C 1-20 alkylsilyl, C 1-20 silylalkyl, C 1-20 alkoxysilyl, C 1-20 alkoxy, C 6-20 aryl, C 7-40 alkylaryl, or C 7-40 arylalkyl, provided that at least one of R 17 to R 21 is C 1-20 haloalkyl, or
two or more of R 22 to R 39 that are adjacent to each other are connected with each other to form a C6-20 aliphatic or aromatic ring unsubstituted or substituted with a C1-10 hydrocarbyl group;
⋅ represents a site of binding to A 1 ; and
* represents a site of binding to M 1 .
9. The method for preparing the polyethylene according to claim 8 , wherein the first metallocene compound is represented by Chemical Formulae 1-1 or 1-2:
in Chemical Formulae 1-1 to 1-2, Q 1 and Q 2 are each independently C 1-3 alkyl; X 1 and X 2 are each independently halogen; A 1 is silicon; M 1 is zirconium or hafnium; R 1 , R 2 , R 4 , R 5 , R 7 , and R 8 are each hydrogen; and R 3 and R 6 are each independently C 2-6 alkyl substituted with C 1-6 alkoxy.
10. The method for preparing the polyethylene according to claim 8 , wherein R 3 and R 6 are each independently unsubstituted C1-6 alkyl or C2-6 alkyl substituted with C1-6 alkoxy.
11. The method for preparing the polyethylene according to claim 8 , wherein the second metallocene compound is represented by Chemical Formula 2-1:
in Chemical Formula 2-1, Q 3 , Q 4 , A 2 , M 2 , X 3 , X 4 , R 11 , and R 17 to R 29 are the same as defined in Chemical Formula 2.
12. The method for preparing the polyethylene according to claim 8 , wherein R 17 to R 21 are each independently hydrogen, or C1-6 haloalkyl, provided that at least one of R 17 to R 21 is C1-6 haloalkyl.
13. The method for preparing the polyethylene according to claim 8 , wherein a weight ratio of the first metallocene compound and the second metallocene compound is 40:60 to 75:25.
14. The method for preparing the polyethylene according to claim 8 , wherein the polymerization is carried out while introducing 30 ppm to 60 ppm of hydrogen gas based on ethylene content.
15. The method for preparing the polyethylene according to claim 8 , wherein the first metallocene compound is represented by Chemical Formulae 1-3 or 1-4:
in Chemical Formulae 1-3 to 1-4, Q 1 , Q 2 , A 1 , M 1 , X 1 , X 2 , and R 3 to R 6 are the same as defined in Chemical Formula 1, and R′ and R″ are the same as or different from each other, and are each independently a C1-10 hydrocarbyl group.
16. The method for preparing the polyethylene according to claim 8 , wherein the second metallocene compound is represented by the following Chemical Formula:
17. A chlorinated polyethylene prepared by reacting the polyethylene according to claim 1 with chlorine.
18. The chlorinated polyethylene according to claim 17 , wherein the chlorinated polyethylene has an elongation of 1000% or more when measured in accordance with ASTM D-412.
19. The chlorinated polyethylene according to claim 17 , wherein the chlorinated polyethylene has a chlorine content of about 20 wt % to about 45 wt %.