Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-12-28
2002-07-23
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
active
06423782
ABSTRACT:
TECHNICAL FIELD
The present invention relato a propylene-based copolymer and to moldings formed by molding the copolymer. More precisely, the invention relates to a propylene-based copolymer and its moldings which are transparent and have good ordinary impact resistance, good cold impact resistance, and well-balanced flexibility and blocking resistance.
BACKGROUND ART
In the field of polypropylene resins, more rigid materials are much studied and developed, while, on the other hand, softer materials are being specifically noted. In this field, desired are soft materials that are more flexible and more transparent and have better impact resistance.
To meet the requirement, propylene homopolymers, propylene-ethylene random copolymers, and propylene block copolymers produced by first preparing a propylene homopolymer or copolymer in the first stage followed by randomly copolymerizing propylene with any other &agr;-olefins in the second stage have been proposed. However, propylene homopolymers are poorly flexible and poorly resistant to shock. Propylene-ethylene random copolymers are also poorly flexible and poorly resistant to shock, though they are transparent. Conventional propylene block copolymers are resistant to shock as they have a sea-island structure composed of a crystalline phase and an amorphous phase, but the components constituting them have a different refractive index. Therefore, their drawbacks are that they are poorly transparent and poorly flexible. In the prior art at present, no one can obtain polypropylene-based polymers that are transparent and have good ordinary impact resistance, good cold impact resistance, and well-balanced flexibility and blocking resistance.
The present invention is to provide a propylene-based copolymer and its moldings which are transparent and have good ordinary impact resistance, good cold impact resistance, and well-balanced flexibility and blocking resistance.
DISCLOSURE OF THE INVENTION
We, the present inventors have assiduously studied so as to solve the problems noted above, and, as a result, have found that a propylene-based copolymer obtained in high-temperature multi-stage vapor-phase polymerization of propylene and comonomer in the presence of a catalyst that comprises a solid catalyst component comprising magnesium, titanium, halogen atom and a specific electron donor compound, along with an organoaluminium compound and a specific organosilicon compound, with varying the comonomer content of the copolymer, is transparent and has good ordinary impact resistance, good cold impact resistance and well-balanced flexibility and blocking resistance. On the basis of this finding, we have completed the present invention. Specifically, the invention provides a propylene-based copolymer and its moldings mentioned below.
1. A propylene-based copolymer comprising from 50 to 90% by weight of a propylene-ethylene copolymer [A] that satisfies the following (1) to (3), and from 10 to 50% by weight of a propylene-ethylene copolymer [B] having an ethylene content of from 10 to 25% by weight:
(1) Its ethylene content (&agr;) measured in
13
C-NMR falls between 0.2 and 10% by weight;
(2) The amount of its fraction (Wp) eluted within the temperature range between (Tp−5)° C. and (Tp+5)° C. is at least 20% by weight, with Tp (°C.) being the peak temperature for essential elution in temperature-programmed fractionation chromatography of the copolymer; and
(3) The amount of its fraction (W0) eluted within the temperature range not higher than 0° C. in temperature-programmed fractionation chromatography of the copolymer, and &agr; satisfy a relation of W0≦(3+2&agr;)/4.
2. The propylene-based copolymer of above 1, which is obtained in propylene block copolymerization for copolymerizing propylene and ethylene in multiple stages.
3. The propylene-based copolymer of above 1 or 2, which comprises from 50 to 85% by weight of a propylene-ethylene copolymer [A] that satisfies the following (1) to (3), and from 15 to 50% by weight of a propylene-ethylene copolymer [B] having an ethylene content of from 10 to 25% by weight:
(1) Its ethylene content (&agr;) measured in
13
C-NMR falls between 0.5 and 9% by weight;
(2) The amount of its fraction (Wp) eluted within the temperature range between (Tp−5)° C. and (Tp+5)° C. is at least 20% by weight, with Tp (°C.) being the peak temperature for essential elution in temperature-programmed fractionation chromatography of the copolymer; and
(3) The amount of its fraction (W0) eluted within the temperature range not higher than 0° C. in temperature-programmed fractionation chromatography of the copolymer, and &agr; satisfy a relation of W0<(3+2&agr;)/4.
4. The propylene-based copolymer of any of above 1 to 3, which satisfies the following requirement:
TM>2×10
5
×(&bgr;)
−1.7
wherein &bgr; indicates the amount of the component [B] (% by weight) in the copolymer, and TM indicates the tensile modulus (MPa) of the copolymer.
5. The propylene-based copolymer of any of above 2 to 4, for which the propylene block copolymerization in above 2 is for multi-stage polymerization of propylene and ethylene in the presence of a catalyst that comprises (A) a solid catalyst component obtained by reacting a magnesium compound, a titanium compound and an electron donor compound through their contact with each other, (B) an organoaluminium compound, and (C) an organosilicon compound of the following general formula (I):
SiR
1
2
(OR
2
)
2
(I)
wherein R
1
represents a branched chain hydrocarbon group having from 1 to 20 carbon atoms, or a saturated cyclic hydrocarbon group; R
2
represents a linear or branched chain hydrocarbon group having from 1 to 4 carbon atoms; and these may be the same or different.
6. The propylene-based copolymer of any of above 2 to 4, for which the propylene block copolymerization in above 2 is for multi-stage polymerization of propylene and ethylene in the presence of a catalyst that comprises (A) a solid catalyst component obtained by contacting a magnesium compound, a titanium compound, an electron donor compound and optionally a silicon compound with each other at a temperature falling between 120° C. and 150° C., followed by washing the resulting product in an inert solvent at a temperature falling between 100° C. and 150° C., (B) an organoaluminium compound, and optionally (C) an electron donor compound serving as a third component.
7. A molding of the propylene-based copolymer of any of above 1 to 4.
BEST MODES OF CARRYING OUT THE INVENTION
The propylene-based copolymer [I] and the moldings [II] formed by molding the copolymer of the invention are described in detail hereinunder.
[I] Propylene-based Copolymer:
The propylene-based copolymer of the invention comprises from 50 to 90% by weight of a propylene-ethylene copolymer [A] that satisfies the following (1) to (3), and from 10 to 50% by weight of a propylene-ethylene copolymer [B] having an ethylene content of from 10 to 25% by weight:
(1) Its ethylene content (&agr;) measured in
13
C-NMR falls between 0.2 and 10% by weight;
(2) The amount of its fraction (Wp) eluted within the temperature range between (Tp−5)° C. and (Tp+5)° C. is at least 20% by weight, with Tp (°C.) being the peak temperature for essential elution in temperature-programmed fractionation chromatography of the copolymer; and
(3) The amount of its fraction (W0) eluted within the temperature range not higher than 0° C. in temperature-programmed fractionation chromatography of the copolymer, and &agr; satisfy a relation of W0≦(3+2&agr;)/4.
The propylene-based copolymer of the invention satisfies the requirements noted above, and its moldings are transparent and have good ordinary impact resistance, good cold impact resistance and well-balanced flexibility and blocking resistance. For example, films formed out of the copolymer have a tensile modulus of at most 1000 MPa and a haze of at most 15%, pref
Endo Masahiko
Kijima Masato
Nakagawa Takayuki
Yukimasa Shinichi
Idemitsu Petrochemical Co. Ltd.
Nutter Nathan M.
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