BIMODAL TERPOLYMER
New bimodal propylene terpolymer, which combines low sealing initiation temperature (SIT), high melting temperature, good processability and good optical properties, like low haze, its use and articles made therefrom.
1 . A bimodal random propylene terpolymer, being a binary blend comprising two propylene polymer fractions PPF1 and PPF2 in specific amounts:
a) 25.0 wt % to less than or equal to 50.0 wt % of propylene polymer fraction PPF1 that is a propylene terpolymer comprising propylene monomers, 0.1 to 0.8 wt % ethylene comonomer and 4.0 to 12.0 wt % of one comonomer selected from C 4 -C 10 alpha-olefin, and
b) more than or equal to 50.0 wt % up to 75.0 wt % of propylene polymer fraction PPF2 that is a propylene terpolymer comprising propylene monomers, 1.0 to 5.0 wt % of ethylene comonomer and 4.0 to 15.0 wt % of one comonomer selected from C 4 -C 10 alpha-olefin,
the amount of PPF1 and PPF2 being relative to the total sum of the propylene polymer fractions PPF1 and PPF2,
wherein the bimodal random propylene terpolymer has:
i) a melting temperature (Tm) in the range of 133 to 160° C. as determined by DSC according to ISO 11357,
ii) a sealing initiation temperature (SIT), measured on a 50 μm cast film, in the range of 90 to <108° C.,
iii) a total ethylene content in the range of 0.5 to 4.0 wt %, and
iv) a total C 4 -C 10 alpha-olefin comonomer content in the range of 5.0 to 14.0 wt %.
2 . The bimodal random propylene terpolymer according to claim 1 , wherein the two propylene polymer fractions PPF1 and PPF2 are terpolymers of propylene, ethylene and 1-butene.
3 . The bimodal random propylene terpolymer according to claim 1 , wherein the bimodal random propylene terpolymer has a melting temperature Tm measured via DSC according to ISO 11357 in the range of 133 to 145° C.
4 . The bimodal random propylene terpolymer according to claim 1 , wherein the bimodal random propylene terpolymer has a xylene cold soluble (XCS) amount in the range of 5.0 to below 25.0 wt %, measured according to ISO 16152, 2005, at 25° C.
5 . A process for producing the bimodal random propylene terpolymer according to claim 1 by a sequential polymerization process comprising at least two reactors connected in series, said process comprising the steps:
a) polymerizing in a first reactor (R-1) that is a slurry reactor propylene, ethylene and one comonomer selected from C 4 -C 10 alpha-olefin to obtain a propylene polymer fraction (PPF1) that is a propylene terpolymer comprising propylene monomers, 0.1 to 0.8 wt % ethylene comonomer and 4.0 to 12.0 wt % of one comonomer selected from C 4 -C 10 alpha-olefin,
b) transferring the propylene polymer fraction (PPF1) and unreacted comonomers of the first reactor (R-1) into a second reactor (R-2) that is a first gas-phase reactor-1 (GPR-1),
c) polymerizing in the first gas-phase reactor-1 (GPR-1) propylene, ethylene and one comonomer selected from C 4 -C 10 alpha-olefin in the presence of the propylene polymer fraction (PPF1) to obtain a propylene polymer fraction (PPF2), that is a propylene terpolymer comprising propylene monomers, 1.0 to 5.0 wt % of ethylene comonomer and 4.0 to 15.0 wt % of one comonomer selected from C 4 -C 10 alpha-olefin, said propylene polymer fraction (PPF2) and the propylene polymer fraction (PPF1) forming the bimodal random propylene terpolymer,
d) recovering the bimodal random propylene terpolymer.
6 . (canceled)
7 . An article comprising the bimodal random propylene terpolymer according to claim 1 .
8 . An article according to claim 7 , wherein the article is an unoriented film comprising more than 90 wt % of the bimodal random propylene terpolymer according to claim 1 , wherein the film is a cast film or a blown film.
9 . The article according to claim 8 , wherein the film has a haze according to ASTM D1003-00 determined on a 50 μm cast film of below 3.0%.
10 . The article according to claim 8 , wherein the film has a hot-tack force determined on a 50 μm cast film in the range of from 1.8 to 5.0 N.
11 . A cast film, wherein the cast film has:
i) a sealing initiation temperature (SIT), measured on a 50 μm cast film, in the range of 90 to <108° C.,
ii) a haze according to ASTM D1003-00 determined on a 50 μm cast film of below 3.0%,
iii) a hot-tack force determined on a 50 μm cast film in the range of from 1.8 to 5.0 N, and
iv) a tensile modulus in machine (MD) direction, determined according to ISO 527-3 on cast films with a thickness of 50 μm, in the range of 200 MPa to 500 MPa.
12 . (canceled)