U.S. patent application number 09/764384 was filed with the patent office on 2001-09-13 for propylene-ethylene block copolymer compositions and processes for production thereof.
This patent application is currently assigned to Chisso Corporation. Invention is credited to Komori, Nobutoshi, Matsukawa, Tetsuya, Oka, Takahiro, Terano, Minoru.
Application Number | 20010021732 09/764384 |
Document ID | / |
Family ID | 22015964 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010021732 |
Kind Code |
A1 |
Terano, Minoru ; et
al. |
September 13, 2001 |
Propylene-ethylene block copolymer compositions and processes for
production thereof
Abstract
A propylene-ethylene block copolymer composition is disclosed
which comprises 0.01 to 10% by weight of an A-B type
propylene-ethylene block copolymer (C) consisting essentially of a
polypropylene segment (A) and an ethylene-propylene random
copolymer segment (B), and 99.99 to 90% by weight of a propylene
polymer (D), wherein the A-B type propylene-ethylene block
copolymer (C) comprises 5 to 80% by weight of the
ethylene-propylene random copolymer segment (B) having an ethylene
content of 10 to 90% by weight and the propylene polymer (D)
comprises 60 to 95% by weight of a homopolymer of propylene or a
copolymer of propylene containing a copolymerizable monomer
therewith (D1) and 40 to 5% by weight of an ethylene-propylene
random copolymer (D2).
Inventors: |
Terano, Minoru;
(Ishikawa-ken, JP) ; Oka, Takahiro; (Ichihara-shi,
JP) ; Komori, Nobutoshi; (Ichihara-shi, JP) ;
Matsukawa, Tetsuya; (Yokohama-shi, JP) |
Correspondence
Address: |
McDERMOTT, WILL & EMERY
600 13th Street, N. W.
Washington
DC
20005-3096
US
|
Assignee: |
Chisso Corporation
Osaka-fu
JP
|
Family ID: |
22015964 |
Appl. No.: |
09/764384 |
Filed: |
January 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09764384 |
Jan 19, 2001 |
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09058302 |
Apr 10, 1998 |
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6211300 |
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Current U.S.
Class: |
523/351 ;
525/240; 525/88 |
Current CPC
Class: |
C08L 2666/24 20130101;
C08L 23/10 20130101; C08L 23/10 20130101; C08L 53/00 20130101 |
Class at
Publication: |
523/351 ; 525/88;
525/240 |
International
Class: |
C08L 001/00; C08L
053/00; C08L 023/04 |
Claims
What is claimed is:
1. A propylene-ethylene block copolymer composition which comprises
0.01 to 10% by weight of an A-B type propylene-ethylene block
copolymer (C) consisting essentially of a polypropylene segment (A)
and an ethylene-propylene random copolymer segment (B), and 99.99
to 90% by weight of a propylene polymer (D), wherein the A-B type
propylene-ethylene block copolymer (C) comprises 5 to 80% by weight
of the ethylene-propylene random copolymer segment (B) having an
ethylene content of 10 to 90% by weight and the propylene polymer
(D) comprises 60 to 95% by weight of a homopolymer of propylene or
a copolymer of propylene containing a copolymerizable monomer
therewith (D1) and 40 to 5% by weight of an ethylene-propylene
random copolymer (D2).
2. The composition of claim 1 wherein the A-B type
propylene-ethylene block copolymer (C) has the intrinsic viscosity
of [.eta.].gtoreq.0.2 dl/g.
3. The composition of claim 1 wherein the ethylene content of the
ethylene-propylene copolymer (D2) is 10 to 90% by weight.
4. A process of producing a propylene-ethylene block copolymer
composition of claim 1 which comprises the sequential steps of: a)
continuously supplying an olefin polymerization catalyst and a
propylene monomer to the top area of a tubular type continuous
polymerization apparatus to produce a polypropylene segment (A); b)
continuously supplying an ethylene monomer to the intermediate area
of the tubular type continuous polymerization apparatus in which
the ethylene monomer and the propylene monomer unreacted in the
step (a) are copolymerized to produce an ethylene-propylene random
copolymer segment (B) and sequentially the segment (B) is
chemically bonded to the terminal of the polypropylene segment (A)
by a covalent bond to produce an A-B type propylene-ethylene block
copolymer (C); c) transferring the A-B type propylene-ethylene
block copolymer (C) containing the olefin polymerization catalyst
produced in the step (b) to a single- or multi-stage polymerization
reactor equipped with an agitator; d) supplying a propylene monomer
or a mixed monomer of a propylene monomer and a copolymerizable
monomer therewith to the polymerization reactor, followed by
copolymerizing in the presence of the olefin polymerization
catalyst and the A-B type propylene-ethylene block copolymer (C) to
produce a propylene polymer (D1); and e) supplying a mixed monomer
of ethylene and propylene to the polymerization reactor, followed
by copolymerizing in the presence of the olefin polymerization
catalyst, the A-B type propylene-ethylene block copolymer (C) and
the propylene polymer (D1) to produce an ethylene-propylene random
copolymer (D2), wherein each polymerization time in the steps a)
and b) is controlled within the range of from 0.01 to 10
seconds.
5. The process of claim 4 wherein the total polymerization time for
producing the A-B type block copolymer (C) is controlled between
0.02 and 20 seconds.
6. The process of claim 4 wherein the olefin polymerization
catalyst is a Ziegler catalyst.
7. The process of claim 4 wherein the olefin polymerization
catalyst is a metallocene catalyst.
Description
FIELD OF THE INVENTION
[0001] This invention relates to new propylene-ethylene block
copolymer compositions. More particularly, it relates to
propylene-ethylene block copolymer compositons which are excellent
not only in impact-resistance, but also in transparency,
stress-whitening resistance, gloss and tensile elongation, and
processes for the production thereof.
BACKGROUND OF THE INVENTION
[0002] Crystalline polypropylenes produced by using a stereoregular
olefin polymerization catalyst are excellent in rigidity and
heat-resistance, but have a poor impact resistance, particularly
that at low temperatures, which leads to limited use in various
fields. As a method to provide improved impact resistance at low
temperatures, there has been proposed a process to block
copolymerize propylene with other .alpha.-olefins such as ethylene.
However, the resulting block copolymers are more improved in impact
resistance at low temperatures than crystalline polypropylenes, but
provide lowering in rigidity, hardness, heat resistance,
transparency, whitening resistance, gloss, tensile elongation and
the like, whereby the use thereof is restricted.
[0003] In order to solve the above-mentioned problems encountered
in the block copolymers, a number of methods have been proposed,
for example, a method which comprises a first step of
homopolymerizing propylene in the presence of a catalyst for a
streoregular polymerization, a second step of copolymerizing a
mixed monomer of ethylene and propylene, and then stepwisely
repeating the propylene homopolymerization and the
ethylene-propylene copolymerization. In relation to the
above-mentioned multi-stage polymerization method, Japanese Patent
Kokai 54-152095 discloses using a titanium trichloride solid
catalyst, and Japanese Patent Kokai 58-201816 discloses using an
organoaluminum compound and an electron donating compound in
combination with a titanium tetrachloride solid catalyst.
[0004] There have also been proposed a propylene block copolymer
consisting of a crystalline polypropylene block and an
ethylene-propylene random copolymer block, wherein the crystalline
polypropylene block content is 55 to 95 percent by weight and the
intrinsic viscosity ratio of the both blocks as well as the glass
transition temperature of the ethylene-propylene random copolymer
block are restricted; and a polypropylene block copolymer which
consists of a polymer block mainly comprising propylene and an
ethylene-propylene random copolymer block, wherein the intrinsic
viscosity ratio of the both blocks and the intrinsic viscosity of
the ethylene-propylene random copolymer block are restricted, and
wherein the resulting block copolymer is melt kneaded.
SUMMARY OF THE INVENTION
[0005] An object of the invention is to provide a
propylene-ethylene block copolymer compositon which is improved in
transparency, stress-whitening resistance, gloss and tensile
elongation and has a high impact resistance.
[0006] Another object of the invention is to provide a method for
the production of the propylene-ethylene block copolymer
composition.
[0007] We have extensively studied on the improvement in the impact
resistance of known propylene-ethylene block copolymers and the
factors which affect transparency, stress-whitening resistance,
gloss and tensile elongation of the copolymers, and have found that
those referred to as "block copolymer" in the prior art are in the
state of a micro-blend in which a polypropylene segment and an
ethylene-propylene copolymer segment are not chemically bonded and
also that the propylene-ethylene block copolymers are formulated
into a copolymer composition containing a true block copolymer as
defined in a polymer chemistry in which the polypropylene segment
and the ethylene-propylene copolymer segment are chemically bonded,
thereby providing the improvement in transparency, stress-whitening
resistance, gloss and tensile elongation, as well as impact
resistance.
[0008] According to the invention, there is provided a
propylene-ethylene block copolymer composition (E) which comprises
0.01 to 10% by weight of an A-B type propylene-ethylene block
copolymer (C) consisting essentially of a polypropylene segment (A)
and an ethylene-propylene random copolymer segment (B), and 99.99
to 90% by weight of a propylene polymer (D), wherein the A-B type
propylene-ethylene block copolymer (C) comprises 5 to 80% by weight
of the ethylene-propylene random copolymer segment (B) having an
ethylene content of 10 to 90% by weight and the propylene polymer
(D) comprises 60 to 95% by weight of a homopolymer of propylene or
a copolymer of propylene containing a copolymerizable monomer
therewith (D1) and 40 to 5% by weight of an ethylene-propylene
random copolymer (D2).
[0009] Further, the present invention provides a process of
producing a propylene-ethylene block copolymer composition (E)
which comprises the sequential steps of:
[0010] a) continuously supplying an olefin polymerization catalyst
and a propylene monomer to the top area of a tubular type
continuous polymerization apparatus to produce a polypropylene
segment (A);
[0011] b) continuously supplying an ethylene monomer to the
intermediate area of the tubular type continuous polymerization
apparatus in which the ethylene monomer and the propylene monomer
unreacted in the step (a) are copolymerized to produce an
ethylene-propylene random copolymer segment (B) and sequentially
the segment (B) is chemically bonded to the terminal of the
polypropylene segment (A) by a covalent bond to produce an A-B type
propylene-ethylene block copolymer (C);
[0012] c) transferring the A-B type propylene-ethylene block
copolymer (C) containing the olefin polymerization catalyst
produced in the step (b) to a single- or multi-stage polymerization
reactor equipped with an agitator;
[0013] d) supplying a propylene monomer or a mixed monomer of a
propylene monomer and a copolymerizable monomer therewith to the
polymerization reactor, followed by copolymerizing in the presence
of the olefin polymerization catalyst and the A-B type
propylene-ethylene block copolymer (C) to produce a propylene
polymer (D1); and
[0014] e) supplying a mixed monomer of ethylene and propylene to
the polymerization reactor, followed by copolymerizing in the
presence of the olefin polymerization catalyst, the A-B type
propylene-ethylene block copolymer (C) and the propylene polymer
(D1) to produce an ethylene-propylene random copolymer (D2),
wherein each polymerization time in the steps a) and b) is
controlled within the range of from 0.01 to 10 seconds.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a schematic view showing the outline of the
tubular type continuous polymerization apparatus and the
polymerization reactor used in the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The propylene-ethylene block copolymer composition (E) of
the invention comprises an A-B type block copolymer (C) wherein the
propylene segment (A) and the ethylene-propylene random copolymer
segment (B) are chemically bonded through a covalent bond.
[0017] It has been found that, in the A-B type block copolymer (C),
the polypropylene segment (A) and the ethylene-propylene random
copolymer segment (B) are chemically bonded through a covalent bond
because the weight loss of the copolymer (C) upon extraction with
n-heptane is extremely low. On the other hand, the micro-blend of
the polypropylene and propylene-ethylene random copolymer shows a
very high weight loss upon n-heptane extraction because the
ethylene-propylene random copolymer is extracted with the
n-heptane.
[0018] A molecular weight distribution curve of the A-B type block
copolymer (C) shows one peak, whereas that of the micro-blended
polymers shows at least two peaks, one corresponding to the
polypropylene component and the other to the propylene-ethylene
random copolymer component.
[0019] The intrinsic viscosity of the A-B type block copolymer (C)
affects the impact resistance of the final propylene-ethylene
copolymer composition (E); if it is too low, improvement in an
impact resistance cannot be achieved. It is preferable that the
intrinsic viscosity [.eta.] of the A-B type block copolymer (C) is
equal to or more than 0.2 dl/g ([.eta.].gtoreq.0.2 dl/g), more
preferably equal to or more than 0.5 dl/g ([.eta.].gtoreq.20.5
dl/g).
[0020] The content of the ethylene-propylene copolymer segment (B)
in the A-B type block copolymer (C) has an effect on various
physical properties of the molded products made from the final
propylene-ethylene copolymer (E). If the content thereof is too
low, the resulting product will be decreased in impact resistance.
On the other hand, if it is too high, the rigidity thereof will be
decreased. The content of the ethylene-propylene copolymer segment
(B) is usually 5 to 80 percent by weight, preferably 10 to 70
percent by weight based on the total weight of the A-B type block
copolymer (C).
[0021] The ethylene content of the ethylene-propylene copolymer
segment (B) has also an effect on various physical properties of
the final propylene-ethylene copolymer composition (E). If the
ethylene content is too low, the impact resistance of the resulting
composition (E) will be decreased, whereas if it is too high, the
transparency of said composition (E) will be decreased. The
ethylene content of the ethylene-propylene copolymer segment (B) is
preferably 10 to 90 percent by weight, more preferably 20 to 80
percent by weight.
[0022] If the content of the A-B type block copolymer (C) in the
propylene-ethylene block copolymer composition (E) is too low,
various physical properties of the final molded products,
particularly a stress-whitening resistance, are lowered. If the
content of said block copolymer (C) is too high, a yield per unit
catalyst of the total polymers obtained in the presence of said
block copolymer (C) is decreased. This is not preferable. The
content of the A-B type block copolymer (C) is usually in a range
of from 0.01 to 10 percent by weight, preferably 0.05 to 5 percent
by weight based on the propylene-ethylene block copolymer
composition (E).
[0023] In the propylene-ethylene block copolymer composition (E),
the propylene polymer (D) comprises 60 to 95 percent by weight of
the homo- or co-polymer (D1) of propylene which may contain the
monomer copolymerizable with propylene and 5 to 40 percent by
weight of the ethylene-propylene random copolymers (D2). If the
content of the ethylene-propylene random copolymer (D2) is too low,
the resulting molded product will not have a sufficient impact
resistance, whereas if it is too high, the resulting molded product
will be decreased in rigidity.
[0024] The copolymerizable monomers with propylene include
ethylene, 1-butene, 4-methylpentene-1, styrene, non-conjugated
dienes, and the like. The homo- or co-polymer (D1) of propylene may
contain these comonomers in an amount of 0 to 10 percent based on
the weight of the propylene.
[0025] If the ethylene content of the ethylene-propylene random
copolymer (D2) is too low or too high, the resulting molded
products will be decreased in impact resistance. The ethylene
content of the ethylene-propylene random copolymer (D2) is
preferably 10 to 90 percent by weight, more preferably 20 to 90
percent by weight.
[0026] The propylene-ethylene block copolymer composition (E)
according to the invention can be produced in a tubular type
continuous polymerization apparatus by, in the first stage,
continuously supplying an olefin polymerization catalyst and a
propylene monomer, and a mixture of propylene and ethylene monomers
to prepare the A-B type block copolymers (C) which consist
essentially of the propylene segment (A) and the ethylene-propylene
random copolymer segment (B) chemically bonded to said segment (A),
and subsequently, in the second stage, carrying out a conventional
polymerization of the propylene monomer and a copolymerization of
the ethylene-propylene mixed monomers in the presence of both the
olefin polymerization catalyst and the resulting A-B type block
copolymers (C).
[0027] In the present invention, any known catalysts for olefin
polymerization can be used. It is preferred to use the catalysts
for a stereoregular olefin polymerization. For example, the
catalysts that can be used include titanium trichloride catalysts,
so-called Ziegler catalysts such as carrier-type catalysts in which
titanium tetrachloride is carried on magnesium chloride, and
metallocene catalysts having active points on Ti, Zr or Hf.
[0028] As the titanium trichloride catalysts can be used, without a
special restriction, those catalysts which are disclosed in
Japanese Patent Kokai 57-55906, 56-155208 and 50-108385.
[0029] More specifically, titanium trichloride catalysts can be
used, which are obtained by reducing titanium tetrachloride with
hydrogen or metallic aluminum, followed by pulverizing for
activation or by reducing titanium tetrachloride with an
organoaluminum compound or further activating. Most preferred
catalysts are titanium trichloride compositions prepared by
reducing titanium tetrachloride with an organoaluminum compound,
followed by further activation.
[0030] As the titanium tetrachloride-carried catalysts can be used,
without a special restriction, those catalysts which are disclosed
in Japanese Patent Kokai 50-126590, 51-92885, 52-100596, 52-147688,
56-811, 56-11908, 58-83006, 58-138706, 58-138707 and 58-138710.
[0031] More specifically, titanium tetrachloride-carried catalysts
containing magnesium, titanium, halogen and an ester selected from
esters of polycarboxylic acids and esters of polyhydroxy compounds
can be used, which are obtained by contacting a liquid hydrocarbon
solution of a magnesium compound with a titanium compound in the
liquid state to form a solid product or first preparing a liquid
hydrocarbon solution of the magnesium compound and the titanium
compound and then forming a solid product therefrom, said reaction
of forming the solid product being carried out in the presence of
at least one electron donor selected from monocarboxylic acid
esters, aliphatic carboxylic acids, carboxylic acid anhydrides,
ketones, aliphatic ethers, aliphatic carbonates, alkoxy
group-containing alcohols, aryloxy group-containing alcohols,
organic silicon compounds having an Si--O--C bond and organic
phosphorus compounds having a P--O--C bond, and during or after the
formation of the solid product, contacting the solid product with
the ester selected from esters of polycarboxyic acids and esters of
polyhydroxy compounds.
[0032] As the metallocene catalysts can be used, without a special
restriction, those catalysts which are disclosed in Japanese Patent
Kokai 6-80720, 2-242804, 5-209013, 5-178923, 6-122718, 4-211694,
1-217012, 2-255812, 4-275294, 6-145240, 6-172433 and 63-66206, as
well as WO92/05208, EP0537130, EP0545303, EP0545304, EP0537686 and
DE4121368.
[0033] The metallocene catalysts used in the present process
include a catalyst comprising (A) a transition metal compound
having at least one .pi.-electron conjugated ligand and (B) at
least one compound selected from an aluminoxane, an ionic compound
which reacts with said transition metal compound to form an ionic
complex and Lewis acid, and a catalyst comprising the compound (A),
the compound (B) and (C) an organoaluminum compound.
[0034] Examples of such metallocene catalysts include:
[0035] Dimethylsilylene(3-t-butylcyclopentadienyl)(fluorenyl)
zirconium dichloride,
[0036] Dimethylsilylene(3-t-butylcyclopentadienyl)(fluorenyl)
hafnium dichloride,
[0037] rac-Ethylene bis(indenyl)zirconium dimethyl,
[0038] rac-Ethylene bis(indenyl)zirconium dichloride,
[0039] rac-Dimethylsilylene bis(indenyl)zirconium dimethyl,
[0040] rac-Dimethylsilylene bis(indenyl)zirconium dichloride,
[0041] rac-Ethylene bis(tetrahydroindenyl)zirconium dimethyl,
[0042] rac-Ethylene bis(tetrahydroindenyl)zirconium dichloride,
[0043] rac-Dimethylsilylene bis(tetrahydroindenyl)zirconium
dimethyl,
[0044] rac-Dimethylsilylene bis(tetrahydroindenyl)zirconium
dichloride,
[0045] rac-Dimethylsilylene bis(2-methyl-4,5,6,7-tetrahydroindenyl)
zirconium dichloride,
[0046] rac-Dimethylsilylene
bis(2-methyl-4,5,6,7-tetrahydroindenyl)zirconi- um dimethyl,
[0047] rac-Ethylene bis(2-methyl-4,5,6,7-tetrahydroindenyl)hafnium
dichloride,
[0048] rac-Dimethylsilylene bis(2-methyl-4-phenylindenyl)zirconium
dichloride,
[0049] rac-Dimethylsilylene bis(2-methyl-4-phenylindenyl)zirconium
dimethyl,
[0050] rac-Dimethylsilylene bis(2-methyl-4-phenylindenyl)hafnium
dichloride,
[0051] rac-Dimethylsilylene bis(2-methyl-4-naphthylindenyl)
zirconium dichloride,
[0052] rac-Dimethylsilylene bis(2-methyl-4-naphthylindenyl)
zirconium dimethyl,
[0053] rac-Dimethylsilylene bis(2-methyl-4-naphthylindenyl)hafnium
dichloride,
[0054] rac-Dimethylsilylene bis(2-methyl-4,5-benzoindenyl)zirconium
dichloride,
[0055] rac-Dimethylsilylene bis(2-methyl-4,5-benzoindenyl)zirconium
dimethyl,
[0056] rac-Dimethylsilylene bis(2-methyl-4,5-benzoindenyl)hafnium
dichloride,
[0057] rac-Dimethylsilylene bis(2-ethyl-4-phenylindenyl)zirconium
dichloride,
[0058] rac-Dimethylsilylene bis(2-ethyl-4-phenylindenyl)zirconium
dimethyl,
[0059] rac-Dimethylsilylene bis(2-ethyl-4-phenylindenyl)hafnium
dichloride,
[0060] rac-Dimethylsilylene bis(2-methyl-4,6-diisopropylindenyl)
zirconium dichloride,
[0061] rac-Dimethylsilylene bis(2-methyl-4,6-diisopropylindenyl)
zirconium dimethyl,
[0062] rac-Dimethylsilylene bis(2-methyl-4,6-diisopropylindenyl)
hafnium dichloride,
[0063]
Dimethylsilylene(2,4-dimethylcyclopentadienyl)(3',5'-dimethylcyclop-
entadienyl)titanium dichloride,
[0064]
Dimethylsilylene(2,4-dimethylcyclopentadienyl)(3',5'-dimethylcyclop-
entadienyl)titanium dichloride,
[0065]
Dimethylsilylene(2,4-dimethylcyclopentadienyl)(3',5'-dimethylcyclop-
entadienyl)zirconium dichloride,
[0066]
Dimethylsilylene(2,4-dimethylcyclopentadienyl)(3',5'-dimethylcyclop-
entadienyl)zirconium dichloride,
[0067]
Dimethylsilylene(2,4-dimethylcyclopentadienyl)(3',5'-dimethylcyclop-
entadienyl)zirconium dimethyl,
[0068]
Dimethylsilylene(2,4-dimethylcyclopentadienyl)(3',5'-dimethylcyclop-
entadienyl)hafnium dichloride,
[0069]
Dimethylsilylene(2,4-dimethylcyclopentadienyl)(3',5'-dimethylcyclop-
entadienyl)hafnium dimethyl,
[0070]
Dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2',4',5'-trimethy-
lcyclopentadienyl)titanium dichloride,
[0071]
Dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2',4',5'-trimethy-
lcyclopentadienyl)zirconium dichloride,
[0072]
Dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2',4',5'-trimethy-
lcyclopentadienyl)zirconium dimethyl,
[0073]
Dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2',4',5'-trimethy-
lcyclopentadienyl)hafnium dichloride, and
[0074]
Dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2',4',5'-trimethy-
lcyclopentadienyl)hafnium dimethyl.
[0075] Of these metallocenes, especially preferred are the
following compounds:
[0076]
Dimethylsilylene(2,4-dimethylcyclopentadienyl)(3',5'-dimethylcyclop-
entadienyl)zirconium dichloride,
[0077]
Dimethylsilylene(2,4-dimethylcyclopentadienyl)(3',5'-dimethylcyclop-
entadienyl)zirconium dimethyl,
[0078]
Dimethylsilylene(2,4-dimethylcyclopentadienyl)(3',5'-dimethylcyclop-
entadienyl)hafnium dichloride,
[0079]
Dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2',4',5'-trimethy-
lcyclopentadienyl)zirconium dichloride,
[0080]
Dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2',4',5'-trimethy-
lcyclopentadienyl)zirconium dimethyl,
[0081]
Dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2',4',5'-trimethy-
lcyclopentadienyl)hafnium dichloride, and
[0082]
Dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2',4',5'-trimethy-
lcyclopentadienyl)hafnium dimethyl.
[0083] The transition metal compound (A) can be combined with
Compound (B), or Compounds (B) and (C) to form a catalyst, but it
can be supported on a finely divided carrier. The carrier is an
inorganic or organic compound. The finely divided solid in a
granular or spherical form having a particle diameter of 5 to 300
.mu.m, preferably 10 to 200 .mu.m is used.
[0084] The inorganic compounds used for the carrier include
SiO.sub.2, Al.sub.2O.sub.3, MgO, TiO.sub.2, ZnO or the mixtures
thereof, e.g. SiO.sub.2-Al.sub.2O.sub.3, SiO.sub.2-MgO,
SiO.sub.2-TiO.sub.2, SiO.sub.2-Al.sub.2O.sub.3-MgO. Of these
compounds, those comprising SiO.sub.2 or Al.sub.2O.sub.3 as a main
component are preferred.
[0085] The organic compounds used for the carrier include polymers
or copolymers of .alpha.-olefin of 2-12 carbons such as ethylene,
propylene, 1-butene, 4-methyl-1-pentene, and polymers or copolymers
of styrene or styrene derivatives.
[0086] These catalysts may be previously treated with co-catalysts,
activators and cationizing agents, and may be used in combination
with so-called electron donating compounds such as aromatic esters
and silicon compounds.
[0087] As the co-catalysts can be suitably used various alkyl
aluminum compounds such as triethyl aluminum, tri-isobutyl
aluminum, diethyl aluminum chloride, ethyl aluminum sesquichloride,
diethyl aluminum halides, di-isobutyl aluminum halides, and the
like.
[0088] In the present invention, the A-B type block copolymers (C)
are prepared in a tubular type continuous polymerization apparatus
by continuously supplying an initially high active catalyst, e.g. a
titanium tetrachloride carried on magnesium chloride and a
co-catalyst such as triethyl aluminum, as well as a propylene
monomer, and the ethylene-propylene mixed monomers for
polymerization. The polymerization time ranging from the initiation
of the polymerization of the propylene monomer until the initiation
of the polymerization of the ethylene-propylene mixed monomers is
controlled within the range of from 0.01 to 10 seconds. In
addition, the total polymerization time is controlled within the
range of from 0.02 to 20 seconds to prepare initially the
polypropylene segment (A) and then the ethylene-propylene copolymer
segment (B) for the production of the A-B type block copolymers
(C). By varying each polymerization time, it is possible to vary
the block chain length of each of the segments (A) and (B).
[0089] If the polymerization time for the propylene monomer is too
short, the chain length of the resulting polypropylene segment (A)
becomes insufficient, while a too long polymerization time tends to
fail to give chemical bonding between the polypropylene segment (A)
and the ethylene-propylene copolymer segment (B) and will produce a
micro-blend of these segments (A) and (B). This is not
preferable.
[0090] This polymerization step is fundamentally continuous. By
continuously carrying out the polymerization for approximately one
minute to two hours, it is possible to produce the A-B type block
copolymer (C).
[0091] As to the polymerization reaction, a liquid phase
polymerization is usually used; however, it is also possible to
carry out the reaction using a liquefied propylene or in a vapor
phase containing an inert gas and propylene. In the case where the
liquid phase polymerization is used, it is possible to use, as a
reaction solvent without a special restriction, such solvents that
are usually used in olefin polymerization reactions, such as
toluene, xylene, hexane, heptane, etc.
[0092] The polymerization temperature is not specially restricted,
but is usually in a range of from 0 to 200.degree. C.
[0093] The A-B type block copolymer (C) thus prepared in the
above-mentioned step is used in the following polymerization step
to give the propylene polymer (D). The polymer (D) can be prepared
according to a conventional propylene copolymerization process
either in a batchwise manner or in a continuous manner.
[0094] The homo- or co-polymer of propylene (D1) can be produced by
polymerizing, in the presence of a mixture of the A-B type block
copolymer (C) and a catalyst, a propylene monomer alone or, if
desired, a propylene monomer containing the monomer(s)
copolymerizable with propylene, by using any one of slurry
polymerization methods effected in a hydrocarbon solvent such as
n-hexane, n-heptane, n-octane, benzene, toluene, etc., bulk
polymerization methods in a liquefied propylene and vapor phase
polymerization methods.
[0095] In the case where a slurry polymerization or a bulk
polymerization method is used, the polymerization temperature is
usually in a range of from 20.degree. to 90.degree. C., preferably
50.degree. to 80.degree. C., and the polymerization pressure is in
a range of from 0.1 to 5 MPa. In the case of a vapor phase
polymerization, the polymerization temperature is usually from
20.degree. to 150.degree. C. and the polymerization pressure is
from 0.2 to 5 MPa. In order to control the molecular weight of the
products, hydrogen is usually used to adjust the MFR value of the
resulting polymers in a range of from 0.1 to 1000.
[0096] Subsequently, a copolymerization reaction of the
ethylene-propylene mixed monomers is followed to produce the
ethylene-propylene random copolymers (D2), thereby producing the
propylene-ethylene block copolymer compositon (E) of the present
invention.
[0097] The copolymerization reaction of the ethylene-propylene
mixed monomers is carried out at a temperature in a range of
usually from 20.degree. to 80.degree. C., preferably from 40 to
70.degree. C. under a pressure in a range of from 0.1 to 5 MPa. For
the molecular weight control, the copolymerization reaction is
effected in a vapor phase maintaining the hydrogen concentration
therein in a range of from 0.1 to 10 molar percent. It is also
possible to copolymerize ethylene and propylene with other
.alpha.-olefins and/or non-conjugated dienes.
[0098] In making the molded products by using the
propylene-ethylene block copolymer compositon (E) of the present
invention, various additives and synthetic resins may be added to
the composition (E), if necessary. Such additives include thermal
stabilizers, anti-oxidants, ultraviolet absorbers, antistatic
agents, nucleating agents, lubricants, flame retardants,
anti-blocking agents, colorants and inorganic or organic fillers.
The molded products are made usually by incorporating these
additives into pellets of the propylene-ethylene block copolymer
composition (E), kneading the resulting mixture after heat melting,
and then granulating the melt into pellets to produce the molded
products.
EXAMPLES
1) Measurements of Physical Properties
[0099] The methods of measuring physical properties and the
evaluation standards thereof are shown below.
[0100] a) n-Heptane extraction of A-B type block copolymer (C):
[0101] In a 200 ml flask are placed 0.5 g of the sample and 50 ml
of n-heptane. The mixture is stirred in a nitrogen atmosphere at
room temperature (about 25.degree. C.) for 24 hours, and
centrifuged (3000 rpm, 8 minutes) to remove a supernatant. A series
of these operations is repeated three times, and then the extracted
residue is dried at 60.degree. C. for 2 hours under reduced
pressure. The yield of the resulting polymer is measured to compare
the weights of the polymer before and after the extraction
operation with n-heptane.
[0102] A micro-blended ethylene-propylene random copolymer is
considerably extracted with n-heptane to exhibit a large weight
loss. On the contrary, the copolymer wherein the ethylene-propylene
random copolymer segment is chemically bonded to the polypropylene
segment does not substantially show such a weight loss
[0103] b) Intrinsic viscosity [.eta.]: measured by means of an
Ostwald viscometer (AVS type automatic viscometer, manufactured by
Mitsui Toatsu Chemicals, Inc.) using Tetralin at 135.degree. C. as
a solvent. (unit: dl/g)
[0104] c) Ethylene content: measured by infrared absorption
spectrophotometry. (unit: % by weight)
[0105] d) MFR: measured at 230.degree. C. under a load of 2.16 kg
according to ASTM D-1238. (unit: g/10 min)
[0106] e) Modulus of elasticity in bending: measured according to
JIS K6758. (unit: MPa).
[0107] f) Tensile strength: measured according to JIS K6758. (unit:
MPa)
[0108] g) Tensile elongation: measured according to JIS K6758.
(unit: %)
[0109] h) HDT: measured according to JIS K7207. (unit: .degree.
C.)
[0110] i) Izod impact stength (II): measured according to JIS
K6758. (unit: J/m).
[0111] j) Gloss: measured according to ASTM D523. (unit: %)
[0112] k) Impact-whitening: Using the same test piece as used for
measuring the gloss which has a center of impact of 3.2 mm in
radius, a 200 g weight is allowed to fall from a height of 50 cm on
the test piece and the radius of the whitened part is measured.
(unit: mm)
[0113] l) Haze: measured according to ASTM D1003. (unit: %)
Example 1
[0114] a) Preparation of catalyst
[0115] A mixture of 150 g of magnesium ethoxide, 275 ml of
2-ethylhexyl-alcohol and 300 ml of toluene was stirred at
93.degree. C. for 3 hours in a carbon dioxide atmosphere at 0.3
MPa, and then 400 ml of additional toluene and 400 ml of n-decane
were added. The resulting solution is hereinafter referred to as
magnesium carbonate solution. After stirring at 30.degree. C. for 5
minutes, a mixture of 100 ml of toluene, 30 ml of chlorobenzene, 9
ml of tetraethoxysilane, 8.5 ml of titanium tetrachloride and 100
ml of ISOPAR G (isoparaffin hydrocarbons having an average carbon
number of 10, boiling point: 156-176.degree. C.), 50 ml of the
magnesium carbonate solution was added. The resulting mixture was
stirred for 5 minutes, incorporated with 22 ml of tetrahydrofuran
and stirred at 60.degree. C. for one hour. After terminating
stirring and removing a supernatant liquid, the resulting solid was
washed with 50 ml of toluene, incorporated with 100 ml of
chlorobenzene and 100 ml of titanium tetrachloride, and stirred at
135.degree. C. for one hour. After terminating stirring and
removing a supernatant liquid, the resulting solid was incorporated
with 250 ml of chlorobenzene, 100 ml of titanium tetrachloride and
2.1 ml of di-n-butyl phthalate, and stirred at 135.degree. C. for
1.5 hours. A supernatant liquid was removed away, and the resulting
solid was washed with 600 ml of toluene, 800 ml of ISOPAR G, and
400 ml of hexane in sequence to obtain a solid catalyst.
[0116] b) Polymerization step of A-B type block copolymer (C)
[0117] The A-B type block copolymer (C) was prepared using a
tubular continuous polymerization apparatus (1) as shown in FIG. 1.
A hexane slurry (10 liters) containing 130 g of the catalyst
prepared in the above was charged in vessel (2), to which 0.68
mol/l of propylene was added. Vessel (3) was charged with 0.7 mol/l
of triethyl aluminum, 70 mmol of di-isopropyldimethoxysilane as an
external donor and 10 liters of a hexane solution containing 0.68
mol/l of propylene. Vessel (4) was charged with 10 liters of a
hexane solution containing 0.21 mol/l of ethylene.
[0118] In the first stage, the propylene solution having the
catalyst dispersed therein from the vessel (2) and the propylene
solution containing triethyl aluminum and the like from the vessel
(3) were continuously introduced into the top area of the tubular
continuous polymerization apparatus (1) as shown in FIG. 1, and the
ethylene-containing solution from the vessel (4) was continuously
introduced into the intermediate area of the tubular polymerization
apparatus (1). In the plymerization area (5), the propylene
solution was reacted at 30.degree. C. for 0.1 second to synthesize
a polypropylene segment (A). In the subsequent polymerization area
(6), propylene and ethylene were reacted for 0.1 second to
synthesize an ethylene-propylene copolymer segment (B). The
resulting products were transferred to a stainless steel
polymerization reactor (7) having an inside volume of 50 liters and
equipped with an agitator. This step was continued for one hour,
and then a part of the resulting polymerized slurry was taken out
to determine the intrinsic viscosity [.eta.], ethylene content and
yield of the resulting A-B type block copolymer (C).
[0119] c) n-Heptane extraction of A-B type block copolymer (C)
[0120] The A-B type block copolymer (C) as prepared above and a
mixture of 0.38 g of polypropylene and 0.20 g of ethylene-propylene
copolymer as prepared for comparison were extracted with n-heptane
in the above manner.
1 Weight before Weight after extraction (g) extraction (g) A-B type
block copolymer (C) 0.58 0.55 Comparative mixture 0.58 0.38
[0121] d) Polymerization step of propylene polymer (D)
[0122] After the temperature within the polymerization vessel (7)
was raised to 70.degree. C., propylene and hydrogen were
continuously supplied thereto for 2 hours while maintaining a total
pressure at 0.8 MPa and a ratio of a hydrogen/-propylene in the
vapor phase at 0.24 to synthesize a homo- or co-polymer (D1) of
propylene. Then, propylene was ceased to feed, the temperature
within the vessel (7) was cooled to 30.degree. C., and hydrogen and
unreacted propylene were purged.
[0123] After a temperature within the polymerization vessel (7) was
raised to 60.degree. C., ethylene and propylene were supplied
continuously for 2 hours in such a ratio that the ethylene content
was 35% by weight and polymerized to prepare an ethylene-propylene
random copolymer (D2). During polymerization, hydrogen was supplied
to maintain a hydrogen concentration in a vapor phase at 1 mol %.
After the polymerization was continued for 2 hours, ethylene and
propylene were ceased to supply. The temperature within the vessel
(7) was cooled to 30.degree. C., and unreacted ethylene and
propylene were purged. The hexane slurry was taken out, filtered
off and dried.
[0124] The resulting propylene-ethylene block copolymer composition
(E) was analyzed, with the results shown in Table 1.
[0125] e) Molded product
[0126] 3.0 kg of the powdery product as prepared above was
incorporated with 0.003 kg of a phenolic thermal stabilizer and
0.003 kg of calcium stearate, and the mixture was blended in a
high-speed mixer (trade name: Henschel Mixer) at room temperature
for 10 minutes. The resulting blend was granulated with an extruder
granulator having a screw diameter of 40 mm.
[0127] Then the granules were injection-molded into a test piece
according to JIS using an injection molding machine at a molten
resin temperature of 230.degree. C., at a mold temperature of
50.degree. C.
[0128] The resulting test piece was maintained in a chamber at room
temperature of 23.degree. C. and a humidity of 50% for 72 hours for
conditioning, and then was measured for the physical properties,
with the results shown in Table 1.
Comparative Example 1
[0129] Polymerization of propylene and copolymerization of ethylene
and propylene were carried out under the same conditions as in
Example 1, except that the polymerization step a) for preparing the
A-B type block copolymer (C) was omitted, n-hexane (25 liters) and
then triethyl aluminum (8.9 g) and di-isopropyldimethoxysilane (6.9
g) as an organic silicon compound were charged in the
polymerization vessel (7) and 1.5 g of the same solid catalyst as
used in Example 1 was used in the polymerization step d) for
preparing the propylene polymer (D), to obtain a propylene-ethylene
copolymer composition.
[0130] Molded products were made from the resulting composition
under the same conditions as in Example 1.
[0131] The propylene-ethylene copolymer composition and the molded
products thus obtained were measured for the physical properties,
with the results shown in Table 1.
[0132] The resulting molded products are found inferior to those
obtained in Example 1 in respect of the tensile elongation, impact
resistance, gloss, stress-whitening resistance and
transparency.
Examples 2 & 3 and Comparative Examples 2 & 3
[0133] The same procedure as in Example 1 was used, but varying the
continuation of polymerization to 10 minutes, 2 hours, 50 seconds
and 5 hours, respectively, in the polymerization step b) for
preparing the A-B type block copolymer (C), to prepare a
propylene-ethylene copolymer composition (E) having a different
content of an A-B type block copolymer (C). Molded products were
obtained from the different copolymer compositions (E) under the
same conditions as in Example 1.
[0134] Physical properties of these molded products were measured,
with the results shown in Table 1.
[0135] The physical properties of the resulting molded products are
inferior to those according to the invention, when a content of an
A-B type block copolymer (C) in the propylene-ethylene copolymer
composition (E) is less than that according to the present
invention. When it is more than that according to the invention, a
yield of the total polymers obtained per unit catalyst is lowered.
In such case, the molded products are of no practical use.
2 TABLE 1 Comparative Example Example Item 1 2 3 1 2 3 A-B type
block copolymer (C) Intrinsic viscosity [.eta.] dl/g 0.8 0.7 0.8 --
0.8 0.7 (B) segment content wt % 35 33 34 -- 34 34 Ethylene content
in (B) 40 38 42 -- 35 44 segment wt % Propylene polymer (D)
Ethylene-propylene 12 12 13 13 13 13 copolymer D2 content wt %
Ethylene content in D2 wt % 45 44 48 46 48 46 Composition (E) A-B
type block copolymer 1.8 0.05 5 -- 0.005 12 (C) content wt % MFR
g/10 min. 29 29 28 27 32 31 Yield kg 6.5 6.6 5.5 6.0 6.5 3.4
Injection molded product Modulus of elasticity in 1440 1460 1420
1450 1440 1390 bending MPa Tensile strength MPa 36 36 35 36 36 34
Tensile elongation % >800 >800 >800 50 220 >800 HDT
.degree. C. 116 115 114 116 115 113 Impact strength (II) J/m 111
108 115 98 100 116 Gloss % 95 93 98 78 82 98 Haze % 60 61 62 95 94
69 Impact-whitening mm 0 1 0 15 10 0 [note]: In the table, impact
strength (II) means Izot impact strength (II) at 23.degree. C., and
the value zero of impact-whitening refers no whitening.
Examples 4 & 5 and Comparative Examples 4 & 5
[0136] The same procedure as in Example 1 was used, but varying the
reaction time in the polymerization area (5) in the polymerization
step b) for preparing the A-B type block copolymer (C) in Example 1
to 0.05, 5, 0.005, and 11 seconds, respectively, and the
corresponding reaction time in the polymerization area (6) to 5,
0.05, 11 and 0.005 second, respectively, to prepare the A-B type
block copolymers (C) having a different content of
ethylene-propylene copolymer segment (B). Then a propylene-ethylene
copolymer composition (E) was produced under the same condition as
in Example 1, but using the A-B type block copolymer (C) as
prepared above. Molded products were made therefrom.
[0137] Physical properties of the molded products were measured,
with the results shown in Table 2.
[0138] When the content of the ethylene-propylene copolymer segment
(B) in the A-B type block copolymer (C) is too low or too high, the
physical properties of the molded products are deteriorated.
3 TABLE 2 Comparative Example Example Item 4 5 4 5 A-B type block
copolymer (C) Intrinsic viscosity [.eta.] dl/g 0.8 0.7 0.8 0.7 (B)
segment content wt % 75 8 85 4 Ethylene content in (B) segment 40
38 35 44 wt % Propylene polymer (D) Ethylene-propylene copolymer D2
13 14 14 13 content wt % Ethylene content in D2 wt % 44 45 44 44
Composition (E) A-B type block copolymer 2.5 2.6 2.2 2.1 (C)
content wt % MFR g/10 min. 31 30 32 31 Yield kg 5.8 5.7 5.6 5.6
Injection molded product Modulus of elasticity in bending MPa 1410
1460 1350 1440 Tensile strength MPa 35 36 34 36 Tensile elongation
% >800 440 >800 150 HDT .degree. C. 113 116 111 116 Impact
strength (II) J/m 115 110 115 106 Gloss % 98 92 96 85 Haze % 62 65
61 87 Impact-whitening mm 0 0 2 10 [note]: In the table, the impact
strength (II) refers to Izot impact strength (II) at 23.degree. C.,
and the value zero of impact whitening refers to no whitening.
Examples 6 & 7 and Comparative Examples 6 & 7
[0139] The same procedure as in Example 1 was used, but varying the
propylene content in the vessel (3) to 0.1 mol/l, 2 mol/l, 0.01
mol/l and 2 mol/l, respectively, the ethylene content in the vessel
(4) to 0.5 mol/l, 0.05 mol/l, 0.6 mol/l and 0.01 mol/l,
respectively, and the reaction time in the polymerization area (5)
to 0.3, 0.05, 0.5 and 0.01 second, respectively, to prepare the A-B
type block copolymers (C).
[0140] A propylene-ethylene copolymer composition (E) was then
prepared under the same conditions as in Example 1, but using the
A-B type block copolymers (C) as prepared above. Molded products
were made therefrom.
[0141] Physical properties of the molded products were measured,
with the results shown in Table 3.
[0142] When an ethylene content of the A-B type block copolymer (C)
is too low or too high, physical properties of the molded product
are deteriorated.
Comperative Example 8
[0143] The same procedure as in Example 1 was used, but varying the
propylene content in the vessel (3) to 0.001 mol/l, the ethylene
content in the vessel (4) to 0.002 mol/l, and the reaction times in
the polymerization areas (5) and (6) to 12 seconds, respectively,
to prepare the A-B type block copolymer (C).
[0144] A propylene-ethylene copolymer composition (E) was prepared
under the same condition as in Example 1, but using the A-B type
block copolymer (C) as prepared above. Further, a molded product
was made therefrom.
[0145] Physical properties of the molded products were measured,
with the results shown in Table 3.
[0146] The intrinsic viscosity [.eta.] of the resulting A-B type
block copolymer (C) was so low that the physical properties of the
molded products were deteriorated.
4 TABLE 3 Comparative Example Example Item 6 7 6 7 8 A-B type block
copolymer (C) Intrinsic viscosity [.eta.] dl/g 1.5 0.8 1.6 0.7 0.1
(B) segment content wt % 35 34 85 34 34 Ethylene content in (B) 80
15 92 8 42 segment wt % Propylene polymer (D) Ethylene-propylene
copolymer 14 15 15 14 15 D2 content wt % Ethylene content in D2 wt
% 44 45 45 44 44 Composition (E) A-B type block copolymer 2.7 2.6
2.8 2.2 3.1 (C) content wt % MFR g/10 min. 21 20 19 22 21 Yield kg
5.8 5.7 5.6 5.6 5.6 Injection molded product Modulus of elasticity
in 1450 1430 1440 1420 1420 bending MPa Tensile strength MPa 36 35
35 34 34 Tensile elongation % 440 >800 220 160 110 HDT .degree.
C. 113 112 112 111 111 Impact strength (II) J/m 118 110 115 106 102
Gloss % 93 98 86 88 82 Haze % 61 59 90 88 92 Impact-whitening mm 0
0 9 8 11 [note]: In the table, the impact strength (II) refers to
Izot impact strength (II) at 23.degree. C., and the value zero of
impact whitening refers to no whitening.
Example 8
[0147] In the vessel (2) was charged 10 liters of a toluene
solution of a metallocene-olefin polymerization catalyst comprising
dimethylsilylene bis(2,3,5-trimethylcyclopentadienyl) zirconium
dichloride (26 g), triisobutyl aluminum (1.8 mols) and
N,N-dimethylanilinium tetra(pentafluorophenyl)borate (66 mmols) as
a cationizing agent. The mixture solution was stirred at 30.degree.
C. for 2 minutes. Propylene was dissolved in 10 liters of toluene
in the vessel (3) and ethylene in 10 liters of toluene in the
vessel (4), respectively, at a pressure of 0.8 MPa.
[0148] The solution containing the metallocene catalyst from the
vessel (2) and the propylene-containing solution from the vessel
(3) were introduced to the polymerization area (5), and the
ethylene-containing solution was introduced from the vessel (4) to
the polymerization area (6). Polymerization of propylene and
copolymerization of ethylene and propylene were carried out,
respectively at 30.degree. C. by controlling the reaction time to
0.5 second, to prepare an A-B type block copolymer (C). The
products were transferred to a stainless steel polymerization
reactor (7) (inside volume 50 liters) equipped with an agitator,
the inside of which was replaced with nitrogen gas. A
propylene-ethylene copolymer composition (E) was produced under the
same conditions as in Example 1, and then molded products were made
therefrom. The properties thereof were measured, with the results
shown in Table 4.
Example 9
[0149] An A-B type block copolymer (C) was prepared under the same
conditions as in (a) of Example 1. A hexane slurry containing the
resulting A-B type block copolymer (C) was transferred to the
polymerization reactor (7), and then the hexane layer was removed
by decantation. Triethyl aluminum (8.9 g) and
di-isopropyldimethoxysilane (6.9 g) as an external donor were added
thereto, and the temperature within the reactor was raised to
70.degree. C. Propylene and hydrogen were continuously supplied for
2 hours, while maintaining the total pressure at 3.3 MPa and a
concentration ratio of hydrogen/propylene in a vapor phase at 0.24,
to polymerize propylene. Propylene was ceased to feed, the
temperature within the reactor was cooled to 30.degree. C., and
hydrogen and unreacted propylene were purged to prepare a propylene
polymer (D1).
[0150] The temperature within the polymerization reactor (7) was
then raised to 60.degree. C. Ethylene and propylene were
continuously supplied thereinto for 2 hours by maintaining a
supplying ratio of ethylene at 35% by weight, to copolymerize
ethylene and propylene. The total amount of ethylene supplied was
0.5 kg. During the polymerization, hydrogen was supplied so as to
maintain a hydrogen concentration in a vapor phase at 1 mol %.
After the polymerization was carried out for 2 hours, supply of
ethylene and propylene was ceased, and the temperature within the
reactor was cooled to 30.degree. C., unreacted ethylene and
propylene were purged to obtain powders of a propylene-ethylene
composition (E).
[0151] Molded products were made from the resulting powders as in
Example 1, and measured for the physical properties, with the
results shown in Table 4.
Examples 10 & 11 and Comparative Examples 9 & 10
[0152] The same procedure as in Example 9 was used, but changing
the supplying ratio of ethylene in the copolymerization of ethylene
and propylene to 10, 90, 5 and 99% by weight, respectively.
Physical properties of the resulting copolymer compositions (E) and
molded products made therefrom were measured, with the results
shown in Table 4.
[0153] The rigidity of the molded products are decreased when the
ethylene content in the copolymer composition (E) is too low, and
the impact resistance is lowered when the ethylene content is too
high.
5 TABLE 4 Comparative Example Example Item 8 9 10 11 9 10 A-B type
block copolymer (C) Intrinsic viscosity [.eta.] dl/g 0.7 0.9 0.8
0.8 0.8 0.8 (B) segment content wt % 35 34 35 35 35 35 Ethylene
content in (B) 80 42 40 40 40 40 segment wt % Propylene polymer (D)
Ethylene-propylene 15 14 13 14 13 14 copolymer D2 content wt %
Ethylene content in D2 wt % 45 46 15 75 8 92 Composition (E) A-B
type block copolymer 2.7 3.1 1.8 1.8 1.8 1.8 (C) content wt % MFR
g/10 min. 20 21 28 32 28 30 Yield kg 6.1 5.9 5.8 6.1 5.5 6.2
Injection molded product Modulus of elasticity in 1450 1430 1390
1460 1360 1420 bending MPa Tensile strength MPa 36 35 34 36 32 35
Tensile elongation % 440 >800 >800 >800 >800 440 HDT
.degree. C. 113 112 114 116 110 115 Impact strength (II) J/m 118
110 108 112 96 95 Gloss % 93 98 98 93 95 88 Haze % 63 60 55 63 57
75 Impact-whitening mm 0 0 0 0 0 0 [note]: In the table, impact
strength (II) means Izot impact strength (II) at 23.degree. C., and
the value zero of impact-whitening refers no whitening.
Examples 12 & 13 and Comparative Examples 11 & 12
[0154] The same procedure as in Example 9 was used, but changing
the polymerization time of propylene to 3, 1, 4 and 1/2 hours,
respectively, and also the copolymerization time of ethylene and
propylene to 1, 3, 1/3 and 4 hours, respectively. Physical
properties of the resulting copolymer compositions (E) and molded
products made therefrom were measured, with the results shown in
Table 5.
[0155] The impact resistance of the molded products is markedly
decreased when a polymerization ratio of the copolymer composition
(D2) to the propylene polymer (D) is too low, and the rigidity is
markedly decreased when the polymerization ratio is too high.
6 TABLE 5 Comparative Example Example Item 12 13 11 12 A-B type
block copolymer (C) Intrinsic viscosity [.eta.] dl/g 0.8 0.8 0.8
0.8 (B) segment content wt % 35 35 35 35 Ethylene content in (B)
segment 40 40 40 40 wt % Propylene polymer (D) Ethylene-propylene
copolymer D2 6 35 3 43 content wt % Ethylene content in D2 wt % 42
44 42 45 Composition (E) A-B type block copolymer 1.8 1.8 1.8 1.8
(C) content wt % MFR g/10 min. 42 12 45 8 Yield kg 5.9 6.2 5.3 6.6
Injection molded product Modulus of elasticity in bending MPa 1580
1260 1620 1180 Tensile strength MPa 38 30 39 28 Tensile elongation
% >800 >800 440 240 HDT .degree. C. 118 110 119 108 Impact
strength (II) J/m 80 220 55 250 Gloss % 98 90 95 88 Haze % 58 66 61
72 Impact-whitening mm 0 1 0 3 [note]: In the table, the impact
strength (II) refers to Izot impact strength (II) at 23.degree. C.,
and the value zero of impact whitening refers to no whitening.
[0156] The propylene-ethylene copolymer composition (E) of the
present invention comprises the A-B type block copolymer (C)
wherein the polypropylene segment (A) and the ethylene-propylene
random copolymer segment (B) are chemically bonded. The molded
products from the composition (E) are superior to those from prior
propylene-ethylene copolymer compositions in a variety of physical
properties and especially in stress-whitening resistance. Thus, the
propylene-ethylene copolymer composition (E) provides an enlarged
use of the polypropylene composition.
* * * * *