U.S. patent application number 09/731480 was filed with the patent office on 2001-10-25 for proplylene-based copolymer composition.
Invention is credited to Mizukami, Shigeo, Takayanagi, Kenjiro, Tsuji, Tatsumi.
Application Number | 20010034416 09/731480 |
Document ID | / |
Family ID | 26578593 |
Filed Date | 2001-10-25 |
United States Patent
Application |
20010034416 |
Kind Code |
A1 |
Takayanagi, Kenjiro ; et
al. |
October 25, 2001 |
Proplylene-based copolymer composition
Abstract
A propylene-based copolymer composition comprises: 10 to 60% by
weight of a polymer component (A) comprising propylene as a main
component and having an isotactic index of not less than 90%; and
40 to 90% by weight of a copolymer component (B) comprising
propylene and other .alpha.-olefin having not more than 8 carbon
atoms and containing propylene and ethylene as essential
components, the copolymer component containing cold xylene
insolubles in an amount of from more than 20 to 70% by weight based
on the weight of whole polymers, and cold xylene solubles in an
amount of 10 to 60% by weight based on the weight of whole
polymers, and cold xylene solubles containing an .alpha.-olefin
other than propylene in an amount of less than 20% by weight, and
the composition being obtained by first producing the component (A)
by polymerization and then producing the component (B) by
polymerization. The propylene-based copolymer composition of the
present invention exhibits not only excellent flexibility and
transparency as well as heat resistance substantially identical to
that of propylene homopolymer, but also excellent mechanical
properties such as tensile strength and impact resistance.
Inventors: |
Takayanagi, Kenjiro;
(Yokkaichi-shi, JP) ; Tsuji, Tatsumi;
(Yokkaichi-shi, JP) ; Mizukami, Shigeo;
(Yokkaichi-shi, JP) |
Correspondence
Address: |
Dike, Bronstein, Roberts & Cushman
Intellectual Property Practice Group
EDWARDS & ANGELL, LLP
130 Water Street
Boston
MA
02109
US
|
Family ID: |
26578593 |
Appl. No.: |
09/731480 |
Filed: |
December 6, 2000 |
Current U.S.
Class: |
525/240 ;
525/191 |
Current CPC
Class: |
C08L 23/10 20130101;
C08L 2205/02 20130101; C08L 23/10 20130101; C08L 23/14 20130101;
C08L 2666/04 20130101; C08L 2308/00 20130101 |
Class at
Publication: |
525/240 ;
525/191 |
International
Class: |
C08L 023/04; C08L
023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 7, 1999 |
JP |
11-347706 |
Dec 15, 1999 |
JP |
11-355369 |
Claims
What is claimed is:
1. A propylene-based copolymer composition comprising: 10 to 60% by
weight of a polymer component (A); and 40 to 90% by weight of a
copolymer component (B), wherein said composition is obtained by
first producing the component (A) by polymerization and then
producing the component (B) by polymerization, wherein said polymer
component (A) comprises propylene as a main component and has an
isotactic index of not less than 90%, and said copolymer component
(B) comprises propylene and other .alpha.-olefin having not more
than 8 carbon atoms, and contains propylene and ethylene as
essential components, said copolymer component containing cold
xylene insolubles in an amount of from more than 20 to 70% by
weight based on the weight of whole polymers, and cold xylene
solubles in an amount of 10 to 60% by weight based on the weight of
whole polymers, and said cold xylene solubles containing an
.alpha.-olefin other than propylene in an amount of less than 20%
by weight.
2. A propylene-based copolymer composition according to claim 1,
wherein said component (A) is a propylene homopolymer.
3. A propylene-based copolymer composition according to claim 1 or
2, wherein other .alpha.-olefin having not more than 8 carbon atoms
contained in the component (B) is ethylene.
4. A propylene-based copolymer composition according to claim 1,
which further satisfies the followings (1) to (4): (1) a propylene
content of 85 to 95% by weight; (2) a content of cold xylene
solubles (CXS) in the whole polymers, of 10 to 60% by weight; (3) a
content of the .alpha.-olefin other than propylene (% by weight:
.alpha.t) and the content of the cold xylene solubles (CXS),
satisfying the following equation: CXS>5.alpha.t-25
(5.ltoreq..alpha.t.ltoreq.15); and (4) a melting peak temperature
of not less than 160.degree. C.
5. A propylene-based copolymer composition according to claim 4,
which is produced only from propylene and ethylene.
6. A propylene-based copolymer composition according to claim 1,
having a flexural modulus of 100 to 600 MPa; a haze of a 2 mm-thick
sheet of not more than 70%; and a tensile strength at break of not
less than 30 MPa.
7. A flexible container produced mainly from the propylene-based
copolymer composition as defined in claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a propylene-based copolymer
composition, and more particularly, to a propylene-based copolymer
composition which is excellent not only in heat resistance,
flexibility and transparency, but also in mechanical properties
such as tensile strength and impact resistance.
[0002] Propylene homopolymer has been extensively used in various
applications such as injection-molded products, sheets, films and
containers because of excellent heat resistance and stiffness
thereof. Further, it has been positively studied to use polyolefins
as alternate materials for building materials such as decorative
sheets, and packages for foodstuffs, which have been conventionally
made of polyvinyl chloride. For this reason, it has been required
to develop polyolefins capable of exhibiting excellent flexibility,
heat resistance and transparency. The propylene homopolymer is
excellent in heat resistance but is deteriorated in flexibility and
transparency. Also, polyethylene and ethylene/.alpha.-olefin
copolymers are excellent in flexibility and transparency but are
deteriorated in heat resistance. In consequence, these polyolefins
are used only in limited applications.
[0003] In the above application fields, there have been
conventionally used random copolymers produced by copolymerizing
propylene with a small amount of ethylene and/or an .alpha.-olefin
having 4 to 6 carbon atoms. These random copolymers are excellent
in transparency but exhibit only a low flexibility. Further, the
copolymers suffer from such an essential problem that the heat
resistance thereof is considerably deteriorated.
[0004] As the method of improving the flexibility and transparency
of polypropylene, for example in Japanese Patent Application
Laid-Open (KOKAI) No. 8-100037(1996), there has been proposed a
process for the production of propylene/ethylene block copolymers
exhibiting excellent heat resistance and flexibility comprising
producing a propylene homopolymer having a specific intrinsic
viscosity ratio and then producing a copolymer having an ethylene
content of 25 to 65% by weight by a two-stage polymerization. Also,
in Japanese Patent Application Laid-Open (KOKAI) Nos.
10-316810(1998) and 11-92619(1999), there have been described
propylene-based block copolymers containing random polypropylene as
matrix and exhibiting good flexibility and transparency.
[0005] However, propylene-based polymer compositions which are
well-balanced and improved in heat resistance, transparency and
flexibility, have not been obtained until now.
[0006] As a result of the present inventors' earnest studies for
solving the above problems, it has been found that by first
producing a specific polymer component (A) comprising propylene as
a main component, and then producing a specific copolymer component
(B) comprising propylene and other .alpha.-olefin having not more
than 8 carbon atoms and containing propylene and ethylene as
essential components, the obtained propylene-based copolymer
composition can exhibit not only good flexibility and transparency,
but also excellent mechanical properties such as tensile strength
and impact resistance. The present invention has been attained
based on this finding.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to provide a
propylene-based copolymer composition exhibiting not only excellent
flexibility and transparency as well as heat resistance
substantially identical to that of propylene homopolymer, but also
excellent mechanical properties such as tensile strength and impact
resistance.
[0008] To accomplish the aim, in a first aspect of the present
invention, there is provided a propylene-based copolymer
composition comprising:
[0009] 10 to 60% by weight of a polymer component (A); and
[0010] 40 to 90% by weight of a copolymer component (B),
[0011] wherein said composition is obtained by producing the
component (A) by first-stage polymerization and then producing the
component (B) by second-stage polymerization,
[0012] wherein said polymer component (A) comprises propylene as a
main component and has an isotactic index of not less than 90%,
and
[0013] said copolymer component (B) comprises propylene and other
.alpha.-olefin having not more than 8 carbon atoms and contains
propylene and ethylene as essential components,
[0014] said copolymer component containing a fraction insoluble in
xylene at room temperature (hereinafter referred to as "cold xylene
insolubles") in an amount of from more than 20 to 70% by weight
based on the weight of whole polymers, and a fraction soluble in
xylene at room temperature (hereinafter referred to as "cold xylene
solubles") in an amount of 10 to 60% by weight based on the weight
of whole polymers, and said cold xylene solubles containing an
.alpha.-olefin other than propylene in an amount of less than 20%
by weight.
[0015] In a second aspect of the present invention, there is
provided the propylene-based copolymer composition according to the
above aspect of the present invention, wherein said component (A)
is a propylene homopolymer, and other .alpha.-olefin having not
more than 8 carbon atoms of said component (B) is ethylene.
[0016] In a third aspect of the present invention, there is
provided the propylene-based copolymer composition according to the
above aspects of the present invention, which has a flexural
modulus of 100 to 600 MPa, a haze of a 2 mm-thick sheet of not more
than 70%; and a tensile strength at break of not less than 30
MPa.
[0017] In a fourth aspect of the present invention, there is
provided the propylene-based copolymer composition according to the
above aspects of the present invention, which satisfies the
followings (1) to (4):
[0018] (1) a propylene content of 85 to 95% by weight;
[0019] (2) a content of the cold xylene solubles (hereinafter
sometimes referred to merely as "CXS") in the whole polymers of 10
to 60% by weight;
[0020] (3) a content (wt. %) of the .alpha.-olefin other than
propylene (hereinafter sometimes referred to merely as ".alpha.t")
and the content of the cold xylene solubles (CXS), satisfying the
following formula:
CXS>5.alpha.t-25 (5.ltoreq..alpha.t.ltoreq.15);
[0021] and
[0022] (4) a melting peak temperature of not less than 160.degree.
C.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The present invention will be described in detail below.
[0024] The component (A) as one of constituents of the
propylene-based copolymer composition according to the present
invention, is a polymer comprising propylene as a main component
and has an isotactic index of not less than 90%. The component (A)
is usually composed of crystalline cold xylene insolubles and
amorphous cold xylene solubles. The content of the cold xylene
insolubles is substantially identical to the isotactic index.
[0025] Here, the polymer comprising propylene as a main component
means such a polymer containing propylene-derived constituent units
in an amount of usually not less than 70% by weight, preferably not
less than 90% by weight, more preferably not less than 95% by
weight based on the weight of the polymer. The most preferred
polymer comprising propylene as a main component is a propylene
homopolymer.
[0026] When the isotactic index of the component (A) is less than
90%, the obtained composition tends to be deteriorated in heat
resistance.
[0027] The component (B) as the other constituent of the
propylene-based copolymer composition according to the present
invention, is a copolymer of propylene and other .alpha.-olefin
having 2 to 8 carbon atoms, which comprises propylene and ethylene
as essential components.
[0028] Examples of other .alpha.-olefins used in the present
invention may include, in addition to ethylene as the essential
component, 1-butene, 3-methyl-1-butene, 1-pentene,
4-methyl-1-pentene, 1-hexene, 1-octene or the like. The more
preferred copolymers are those produced only from propylene and
ethylene.
[0029] In accordance with the present invention, the copolymer
component (B) contains cold xylene insolubles in an amount of from
more than 20 to 70% by weight based on the weight of whole
polymers, and cold xylene solubles in an amount of 10 to 60% by
weight based on the weight of whole polymers, and further the cold
xylene solubles contains the .alpha.-olefin other than propylene in
an amount of less than 20% by weight. It is preferred that the
content of the cold xylene insolubles is 25 to 60% by weight based
on the weight of whole polymers; the content of the cold xylene
solubles is 15 to 60% by weight on the weight of whole polymers;
and the content of the .alpha.-olefin other than propylene in the
cold xylene solubles is 10 to 18% by weight.
[0030] Meanwhile, the "whole polymers" used herein represent total
polymers of the components (A) and (B).
[0031] When the component (B) contains the cold xylene insolubles
in an amount of not more than 20% by weight, the obtained
composition tends to be deteriorated in transparency. On the other
hand, when the component (B) contains the cold xylene insolubles in
an amount of more than 70% by weight, the obtained composition
tends to be deteriorated in flexibility. In addition, when the
component (B) contains the cold xylene solubles in an amount of
less than 10% by weight, the obtained composition tends to be
insufficient in flexibility. On the other hand, when the component
(B) contains the cold xylene solubles in an amount of more than 60%
by weight, the obtained composition tends to be deteriorated in
heat resistance.
[0032] When the cold xylene solubles contains the .alpha.-olefin
other than propylene in an amount of not less than 20% by weight,
the obtained composition tends to be deteriorated in
transparency.
[0033] The propylene-based copolymer composition of the present
invention comprises 10 to 60% by weight of the component (A) and 40
to 90% by weight of the component (B), preferably 20 to 50% by
weight of the component (A), and preferably 50 to 80% by weight of
the component (B).
[0034] When the content of the component (A) is less than 10% by
weight and the content of the component (B) is more than 90% by
weight, the obtained composition tends to be deteriorated in heat
resistance. On the other hand, when the content of the component
(A) is more than 60% by weight and the content of the component (B)
is less than 40% by weight, it becomes difficult to obtain a
composition having good flexibility and transparency.
[0035] It is preferred that the propylene-based copolymer
composition of the present invention has as a whole the followings
(1) to (4).
[0036] (1) a propylene content of 85 to 95% by weight;
[0037] (2) a content of the cold xylene solubles (CXS) in the whole
polymers of 10 to 60% by weight;
[0038] (3) a content of the .alpha.-olefin other than propylene
(.alpha.t; unit: wt. %) and the content of the cold xylene solubles
(CXS), satisfying the following formula:
CXS>5.alpha.t-25 (5.ltoreq..alpha.t.ltoreq.15);
[0039] and
[0040] (4) a melting peak temperature of not less than 160.degree.
C.
[0041] The propylene content and the content of the .alpha.-olefin
other than propylene having 2 to 8 carbon atoms (.alpha.t) are in
the range of 85 to 95% by weight and 5 to 15% by weight,
respectively.
[0042] The propylene content is more preferably 87 to 95% by
weight, still more preferably 88 to 92% by weight. The
.alpha.-olefin content (.alpha.t) is more preferably 5 to 13% by
weight, still more preferably 8 to 12% by weight. When the
propylene content is more than 95% by weight and the .alpha.-olefin
content (.alpha.t) is less than 5% by weight, the obtained
composition may tend to be deteriorated in flexibility. On the
other hand, when the propylene content is less than 85% by weight
and the .alpha.-olefin content (.alpha.t) is more than 15% by
weight, the obtained composition may tend to be deteriorated in
transparency.
[0043] The content of the cold xylene solubles (CXS) contained in
the propylene-based copolymer composition is preferably in the
range of 10 to 60% by weight based on the weight of the whole
polymer. When the CXS is less than 10% by weight, the obtained
composition may tend to be insufficient in flexibility. On the
other hand, when the CXS is more than 60% by weight, the obtained
composition may tend to be deteriorated in heat resistance.
[0044] Also, it is preferred that the content of the .alpha.-olefin
other than propylene having 2 to 8 carbon atoms (.alpha.t: wt. %)
and the content of the cold xylene solubles (CXS: wt. %) satisfy
the following formula:
CXS>5.alpha.t-25 (5.ltoreq..alpha.t.ltoreq.15)
[0045] When the CXS does not satisfy the above formula, the
obtained composition may tend to be deteriorated in
transparency.
[0046] The propylene-based copolymer composition capable of
satisfying the above properties exhibits a melting point
substantially identical to that of propylene homopolymer, and a
melting peak temperature as high as not less than 160.degree. C.
This indicates that the propylene copolymer has a high heat
resistance.
[0047] The thus obtained propylene-based copolymer composition can
exhibit a flexural modulus of usually 100 to 600 MPa, preferably
150 to 500 MPa when measured at 23.degree. C. according to JIS
K7203; a tensile strength at break of usually not less than 30 MPa
when measured at 23.degree. C. according to JIS K7113, and a haze
of a 2 mm-thick sheet of usually not more than 70% when measured
according to JIS K6717.
[0048] The propylene-based copolymer composition of the present
invention is obtained by first producing the component (A) by
polymerization and then producing the component (B) by
polymerization in the presence of the obtained component (A).
[0049] For example, the composition is preferably produced by at
least two-stage polymerization method. That is, the propylene
homopolymer is produced by the first-stage polymerization, and then
the copolymer of propylene and the .alpha.-olefin other than
propylene having 2 to 8 carbon atoms which contains propylene and
ethylene as essential components, is produced by the second or
subsequent-stage polymerization, thereby obtaining such a
composition having a propylene content of 85 to 95% by weight based
on the weight of the whole polymer and an .alpha.-olefin content
(.alpha.t) of 5 to 15% by weight based on the weight of the whole
polymer.
[0050] The catalysts usable in the above successive polymerization
are not particularly restricted. As the suitable catalysts, there
may be used those catalysts comprising an organoaluminum compound
and a solid component containing titanium atom, magnesium atom,
halogen atom and an electron donating compound as essential
ingredients.
[0051] As the organoaluminum compounds, there may be used those
compounds represented by the following formula:
R.sup.1.sub.mA1X.sub.(3-m)
[0052] wherein R.sup.1 is a hydrocarbon group having 1 to 12 carbon
atoms; X is a halogen atom; and m is a number of 1 to 3.
[0053] Examples of the organoaluminum compounds may include
trialkyl aluminums such as trimethyl aluminum and triethyl
aluminum; dialkyl aluminum halides such as dimethyl aluminum
chloride and diethyl aluminum chloride; alkyl aluminum
sesquihalides such as methyl aluminum sesquichloride and ethyl
aluminum sesquichloride; alkyl aluminum dihalides such as methyl
aluminum dichloride and ethyl aluminum dichloride; alkyl aluminum
hydrides such as diethyl aluminum hydride; or the like.
[0054] As sources of the titanium atom contained in the solid
component containing titanium atom, magnesium atom, halogen atom
and an electron donating compound as essential ingredients, there
may be exemplified those titanium compounds represented by the
following formula:
Ti(OR.sup.2).sub.(4-n)X.sub.n
[0055] wherein R.sup.2 is a hydrocarbon group having 1 to 10 carbon
atoms; X is a halogen atom; and n is a number of 0 to 4.
[0056] Among these titanium compounds, titanium tetrachloride,
tetraethoxy titanium, tetrabutoxy titanium or the like are
preferred.
[0057] Examples of magnesium compounds used as sources of the
magnesium atom, may include dialkyl magnesium, magnesium dihalide,
dialkoxy magnesium, alkoxy magnesium halide or the like. Among
these magnesium compounds, magnesium dihalide is preferred. As the
halogen atoms, there may be used fluorine, chlorine, bromine and
iodine. Among these halogen atoms, chlorine is preferred. The
halogen atom may be usually supplied from the above titanium
compounds or magnesium compounds. However, the halogen atom may be
supplied from other halogen sources such as aluminum halides,
silicon halides, tungsten halides or the like.
[0058] As the electron donating compounds, there may exemplified
oxygen-containing compounds such as alcohols, phenols, ketones,
aldehydes, carboxylic acids, organic or inorganic acids and
derivatives thereof; nitrogen-containing compounds such as ammonia,
amines, nitriles and isocyanates; or the like. Among these electron
donating compounds, inorganic acid esters, organic acid esters,
organic acid halides, etc., are preferred, and silicic acid esters,
phthalic acid esters, cellosolve acetate, phthalic halide, etc.,
are more preferred.
[0059] As the silicic acid esters, there may be exemplified
organosilicon compounds represented by the following formula:
R.sup.3R.sup.4.sub.(3-p)Si(OR.sup.5).sub.p
[0060] wherein R.sup.3 is a branched aliphatic hydrocarbon residue
having 3 to 20, preferably 4 to 10 carbon atoms, or a cyclic
hydrocarbon residue having 5 to 20, preferably 6 to 10 carbon
atoms; R.sup.4 is a branched or linear aliphatic hydrocarbon
residue having 1 to 20, preferably 1 to 10 carbon atoms; R.sup.5 is
an aliphatic hydrocarbon residue having 1 to 10, preferably 1 to 4
carbon atoms; and p is a number of 1 to 3.
[0061] Examples of the preferred organosilicon compounds may
include tert-butyl-methyl-dimethoxysilane,
tert-butyl-methyl-diethoxysilane,
cyclohexyl-methyl-dimethoxysilane, cyclohexyl-methyl diethoxysilane
or the like.
[0062] The propylene-based copolymer composition of the present
invention can be produced by the following two-stage polymerization
method. Namely, at the first stage, propylene or propylene and
other .alpha.-olefin having 2 to 8 carbon atoms are supplied to
conduct the polymerization of .alpha.-olefin containing propylene
as a main component at a temperature of 50 to 150.degree. C.,
preferably 50 to 100.degree. C. under a propylene partial pressure
of 0.5 to 4.5 MPa, preferably 1.0 to 3.5 MPa in the presence of the
above-described catalyst, thereby producing the component (A).
Then, at the second stage, propylene and ethylene, or propylene,
ethylene and .alpha.-olefin having 4 to 8 carbon atoms are supplied
to conduct the copolymerization between propylene and ethylene or
between propylene, ethylene and the .alpha.-olefin at a temperature
of 50 to 150.degree. C., preferably 50 to 100.degree. C. under
propylene and ethylene partial pressures each being 0.3 to 4.5 MPa,
preferably 0.5 to 3.5 MPa, in the presence of the above-described
catalyst, thereby producing the component (B).
[0063] The above polymerization reactions may be conducted by
either a batch process, a continuous process or a semi-batch
process. The first-stage polymerization may be carried out in gas
phase or liquid phase, and the second-stage or subsequent
polymerization may also be carried out in gas phase or liquid
phase, preferably in gas phase. The residence time at each stage is
0.5 to 10 hours, preferably 1 to 5 hours.
[0064] In the process of the present invention, the respective
contents of the components (A) and (B) may be controlled by amounts
of monomers to be polymerized at each stage, and the isotactic
index of the component (A) may be controlled by kind of catalyst
used, polymerization conditions (such as temperature and pressure)
or composition of monomers charged. In addition, the cold xylene
insolubles or cold xylene solubles of the component (B) may be
controlled by composition of monomers charged at each stage,
amounts of polymers produced at each stage and molecular weights
thereof (the molecular weights can be adjusted, for example, by
amount of hydrogen supplied), as well as by kind of catalyst
selected.
[0065] Further, it is preferred that the .alpha.-olefin content
(.alpha.t) is controlled by composition of monomers charged at each
stage, and the CXS and the melting peak temperature are controlled
by the ratio between amount of polymers produced at the first stage
to that produced at the second and subsequent stages or molecular
weights thereof which can be adjusted, for example, by amount of
hydrogen supplied.
[0066] In the case where the polymers produced by the above methods
cause problems such as sticky polymer particles, it is preferred
that an active hydrogen-containing compound is added in an amount
of 100 to 1,000 moles based on one mole of titanium atom contained
in solid component of the catalyst or in an amount of 2 to 5 moles
based on one mole of the organoaluminum compound contained in the
catalyst in order to impart a good fluidity to the particles.
[0067] Examples of the active hydrogen-containing compounds may
include water, alcohols, phenols, aldehydes, carboxylic acids, acid
amides, ammonia, amines or the like.
[0068] The propylene-based copolymer composition of the present
invention may further contain ethylene-based polymers such as
ethylene/.alpha.-olefin copolymer and ethylene/vinyl acetate
copolymer, propylene-based polymers such as
propylene/.alpha.-olefin copolymer and syndiotactic polypropylene,
and hydrogenated products of block copolymers of styrene and
conjugated diene such as butadiene and isoprene, unless the
addition thereof adversely affects the transparency or heat
resistance of the obtained composition. Also, .alpha.-crystal
nucleating agents ordinarily used for enhancing the transparency of
propylene-based polymers may be added to the composition. Further,
rubber softening agents may be blended in the composition in order
to impart a good flexibility thereto.
[0069] Furthermore, the propylene-based copolymer composition of
the present invention may contain, if required, various resins or
rubbers other than those described above, fillers such as glass
fibers, calcium carbonate, silica, talc, mica and clays, various
additives such as antioxidants, light stabilizers, anti-static
agents, lubricants, dispersants, neutralizers and flame retardants,
and the like unless the addition thereof adversely affects the
effects of the present invention.
[0070] The propylene-based copolymer composition of the present
invention can be molded into a desired shape by various molding
methods used for polyolefins such as extrusion molding method,
injection molding method, compression molding method or the like,
in order to produce single products, laminates with other materials
or the like.
[0071] Thus, the propylene-based copolymer composition of the
present invention exhibits not only good heat resistance,
flexibility and transparency, but also excellent mechanical
properties such as tensile strength at break and impact
resistance.
EXAMPLES
[0072] The present invention will be described in more detail by
reference to the following examples. However, these examples are
only illustrative and not intended to limit the present invention
thereto.
Production of Propylene-based Copolymer Composition
[0073] Propylene-based copolymer compositions used in Examples and
Comparative Examples were produced by the following methods.
[0074] (1) Production of solid catalyst
[0075] A 50-liter reaction vessel equipped with a stirrer was
purged with nitrogen, and then charged with 20 liters of dehydrated
and deoxygenated n-heptane and then with 4 moles of magnesium
chloride and 8 moles of tetrabutoxy titanium. The contents were
reacted with each other at 95.degree. C. for 2 hours, cooled to
40.degree. C., and then mixed with 480 ml of
methylhydropolysiloxane (viscosity: 20 centistoke). The resultant
mixture was further reacted for 3 hours. Then, the obtained
reaction solution was taken out of the reaction vessel, and the
produced solid component was separated from the reaction solution
and washed with n-heptane.
[0076] Successively, a stirrer-equipped reaction vessel of the same
type as used above was charged with 15 liters of dehydrated and
deoxygenated n-heptane and then with 3 moles of the obtained solid
component (calculated as magnesium atom). Further, a mixed solution
prepared by adding 8 moles of silicon tetrachloride to 25 ml of
n-heptane was introduced into the reaction vessel at 30.degree. C.
for 30 minutes, and the resultant mixture was heated to 90.degree.
C. and reacted for one hour. Thereafter, the obtained reaction
solution was taken out of the reaction vessel, and the obtained
solid component was separated from the reaction solution and washed
with n-heptane.
[0077] Furthermore, a stirrer-equipped reaction vessel of the same
type as used above was charged with 5 liters of dehydrated and
deoxygenated n-heptane and then with 250 g of the obtained silicon
tetrachloride-treated titanium-containing solid component, 750 g of
1,5-hexadiene, 130 ml of tert-butyl-methyl-dimethoxysilane, 10 ml
of divinyl dimethylsilane and 225 g of triethyl aluminum. The
contents of the reaction vessel were contacted with each other at
30.degree. C. for 2 hours. Then, the obtained reaction solution was
taken out of the reaction vessel, and the obtained solid component
was separated from the reaction solution and washed with n-heptane,
thereby obtaining a solid catalyst.
[0078] The thus obtained solid catalyst had 2.97 g of
pre-polymerized 1,5-hexadiene based on one gram of
titanium-containing solid component.
[0079] (2) Two stage polymerization of
propylene/propylene-ethylene
[0080] A 550-liter first stage reactor was continuously charged
with propylene and triethyl aluminum, and then with the
above-obtained solid catalyst in such an amount that the polymer
production velocity was 20 kg/hour, at 70.degree. C. under
increased pressure (about 3.2 MPa at 70.degree. C.). Further, the
reactor was continuously charged with hydrogen as a molecular
weight-controlling agent to conduct the first stage polymerization
in a liquid phase.
[0081] Successively, the obtained polymer was passed through a
propylene-purged vessel and then introduced into a second stage
reactor having a capacity of 1,900 liters. Then, the second reactor
was continuously charged with propylene and ethylene in amounts
according to the composition of aimed copolymer so as to adjust the
pressure thereof to 3.0 MPa at 60.degree. C. Further, the reactor
was continuously charged with hydrogen as a molecular
weight-controlling agent and then with ethanol as an active
hydrogen-containing compound in an amount of 200 moles based on one
mole of titanium atom contained in the solid catalyst charged at
the first stage, and in an amount of 2.5 moles based on one mole of
triethyl aluminum. The contents of the reactor were reacted with
each other in a gas phase. After the obtained polymer was
continuously transferred into vessel, the reaction was stopped by
introducing a water vapor-containing nitrogen gas into the reactor
(second stage polymerization).
Examples 1 to 11 and Comparative Examples 1 to 5
[0082] According to the above-described method, polymer
compositions having various contents of cold xylene solubles (CXS)
and cold xylene insolubles (CXIS) were produced while controlling
amounts of raw monomers charged (such as propylene).
[0083] Composition analysis:
[0084] The compositions composed of polymers obtained in Examples
and Comparative Examples were measured to determine weight
percentages of the components (A) and (B) based on whole polymers,
weight percentages of cold xylene insolubles and cold xylene
solubles in the respective components (A) and (B) based on whole
polymers, isotactic index of the component (A), and content of
.alpha.-olefin (ethylene) other than propylene in the cold xylene
solubles. The results are shown in Tables 1 and 2.
[0085] (i) Weight percentages of components (A) and (B) based on
whole composition:
[0086] The weight percentage of the component (B) based on whole
polymers (hereinafter referred to as "B (%)") was calculated from
the weight of whole polymers obtained and weights of propylene and
ethylene fed to the second stage polymerization. The weight
percentage of the component (A) based on whole polymers
(hereinafter referred to as "A (%)") was calculated from the weight
percentage of the component (B) according to the following
formula:
A=100-B
[0087] (ii) Weight percentage of amorphous cold xylene solubles
(CXS):
[0088] One gram of polymers produced by the first stage
polymerization were sampled and added to 300 ml of xylene retained
in an oil bath. The mixture was stirred at 140.degree. C., i.e., at
a boiling point of xylene to dissolve the polymers in xylene. The
obtained solution was continuously stirred for one hour.
Successively, while continuously stirring, the solution was cooled
to 100.degree. C. within one hour, and then transferred to a
quenching oil bath where the solution was rapidly cooled to
23.+-.2.degree. C., thereby precipitating polymers. The solution
was allowed to stand for not less than 20 minutes, and passed
through a filter paper to separate precipitates therefrom by
natural filtration. The obtained filtrate was evaporated to dryness
using an evaporator to obtain solids. The obtained solids were
dried at 120.degree. C. under reduced pressure for 2 hours, and
then allowed to stand for cooling to ordinary temperature to
measure the weight of cold xylene solubles contained in the
component (A). The thus obtained weight of the cold xylene solubles
contained in the component (A) was compared with the initial weight
of the sample to calculate the weight percentage of the cold xylene
solubles contained in the component (A) (hereinafter referred to as
"As" (wt. %)).
[0089] The weight of cold xylene solubles contained in whole
polymers produced was measured by the same method as used above to
calculate the weight percentage thereof (hereinafter referred to as
"CXS(P)" (wt.%)).
[0090] Then, the weight percentage of cold xylene solubles
contained in the component (A) based on whole polymers (hereinafter
referred to as "CXS(A)" (wt. %)) was calculated according to the
formula: As.times.A/100. Similarly, the weight percentage of cold
xylene solubles contained in the component (B) based on whole
polymers (hereinafter referred to as "CXS(B)" (wt. %)) was also
calculated according to the formula: CXS(P)-CXS(A).
[0091] (iii) Isotactic index of component (A):
[0092] The polymers (component (A)) produced by the first stage
polymerization were sampled by the same method as used in the above
(ii), and subjected to Soxhlet's extraction using n-heptane. The
weight of the obtained residues was measured to calculate the
weight percentage (%) thereof based on the weight of the
sample.
[0093] (4) Ethylene content of cold xylene solubles contained in
component (B):
[0094] The cold xylene solubles contained in the polymers produced
by the first stage polymerization in the above (ii) and the cold
xylene solubles contained in whole polymers, were measured by
.sup.13C-NMR spectrum method as described in Kang-Bong Lee, et. al,
"Polymer J.", 28, pp. 696-702 (1996), to determine ethylene
contents of the respective cold xylene solubles (hereinafter
referred to as "E(A)" and "E(P)" (wt. %), respectively). The
ethylene content of cold xylene solubles contained in the component
(B) is calculated according to the following formula:
[E(P)-E(A).times.(CXS(A)/CXS(P))]/[CXS(B)/CXS(P)]
[0095] Evaluation of polymers:
[0096] The melt flow rate (MFR) and density of the obtained
propylene-based copolymer composition were measured by the
following methods (1) and (2), respectively.
[0097] Also, the hardness, mechanical properties, haze, etc. of the
obtained propylene-based copolymer composition were measured by the
following methods (3) to (8) using a sample produced by the method
described below.
[0098] That is, 0.05 part by weight of each of
tetrakis[methylene-3-(3',5'- -di-tert-butyl-4'-hydroxyphenyl)
propionate]methane ("IRGANOX 1010" produced by Japan Ciba Geigy
Co., Ltd.) and tris(2,4-di-tert-butyl phenyl)phosphite ("IRGAFOS"
produced by Japan Ciba Geigy Co., Ltd.) as antioxidants, and 0.05
part by weight of zinc stearate as neutralizing agent were added to
100 parts by weight of the propylene-based copolymer composition.
The resultant composition was melt-kneaded and extruded into
pellets at a set temperature of 200.degree. C. using a twin-screw
extruder having a cylinder diameter of 45 mm ("PCM45" manufactured
by Ikegai Tekko Co., Ltd.). Then, the obtained pellets were
injection-molded using an injection molding machine ("N-100"
manufactured by Nihon Seikosho Co., Ltd.) having a clamping
pressure of 100 tons, at a hopper bottom temperature of 175.degree.
C., a cylinder temperature of 220.degree. C., a nozzle temperature
of 210.degree. C. and a mold temperature of 40.degree. C., thereby
obtaining an injection-molded test sample. The test sample was
measured to determine a melt flow rate (MFR), density, hardness,
flexural modulus, tensile strength, impact strength, haze and
melting peak temperature thereof by the following methods. The
results are shown in Tables 1 and 2.
[0099] (1) The melt flow rate (MFR) was measured at 230.degree. C.
under a load of 21.18N according to JIS K7210.
[0100] (2) The density was measured by a water substitution method
according to JIS K7112.
[0101] (3) The hardness was determined by measuring a type D
duro-meter hardness according to JIS K7215.
[0102] (4) The thermal property (melting peak temperature) was
measured at a temperature rise rate of 10.degree. C./minute
according to JIS K7121 using a differential scanning calorimeter
(DSC; manufactured by Seiko Instruments Co., Ltd.).
[0103] (5) The flexural modulus and flexural strength were measured
at 23.degree. C. according to JIS K7203.
[0104] (6) The tensile properties such as tensile strength at yield
point, tensile strength at break and tensile elongation at break,
were measured at 23.degree. C. and a pulling speed of 50 mm/minute
by using a JIS dumbbell No. 2 according to JIS K7113.
[0105] (7) The impact strength was determined by measuring notched
Izod impact strengths at 23.degree. C. and 0.degree. C. according
to JIS K7110.
[0106] (8) The haze of the above test sample, i.e., the 2 mm-thick
injection-molded sheet produced above for measurement of mechanical
properties, was measured according to JIS K6717.
Evaluation of Results
[0107] From the results shown in Table 1, the following facts were
confirmed.
[0108] (I) In Comparative Examples 1 to 3 where the content of cold
xylene insolubles in the component (B) and the ethylene content of
the cold xylene solubles were out of the specified ranges according
to the present invention, the obtained compositions all exhibited a
high haze value and were insufficient in transparency.
[0109] (II) In Comparative Example 4 where the contents of the
components (A) and (B) and the CXIS of the component (B) were out
of the specified range according to the present invention, the
obtained composition was insufficient in impact resistance.
Example 12 and Comparative Example 6
Preparation of Film and Bag
[0110] The compositions obtained in Example 10 and Comparative
Example 4 were respectively molded into a tubular film having a lay
flat width of 150 mm and a thickness of 250 .mu.m by using a
water-cooled inflation molding machine manufactured by Placo Co.,
Ltd. (die diameter: 100 mm.phi.; die lip: 3 mm; dice temperature:
200.degree. C.). A test sample was cut from the tubular film, and
heat-sealed at one open end thereof to form a bag. The bag was
filled with 700 cc of pure water, and then heat-sealed at the other
open end thereof to form a closed bag.
[0111] Transparency before and after high-temperature and
high-pressure sterilization treatment:
[0112] The thus obtained bag was placed in a high-temperature and
high-pressure cooking sterilization tester ("RCS/40RTGN-Model"
manufactured by Hitachi Limited), and then pressurized while
increasing the ambient temperature up to 121.degree. C. at which
the bag was then kept for 30 minutes so as to subject the bag to
high-temperature and high-pressure sterilization treatment. After
completion of the treatment, the bag was removed from the tester,
and a 250 .mu.m-thick film was cut from the bag. The haze of the
cut film was compared with that before the treatment. The results
are shown in Table 2. It was confirmed that the composition of the
present invention still maintained a high transparency.
[0113] Drop test for bag:
[0114] The above bag was chilled at 4.degree. C. for one day in a
refrigerator. Then, the bag was dropped from a predetermined height
within the refrigerator to measure the falling bag impact strength.
The drop heights were set to 0.5 m, 1 m, 1.5 m and 2 m, and the bag
was dropped three times at each height. The falling bag impact
strength is expressed by the height causing breakage of the bag
when being dropped therefrom. The results are shown in Table 2. The
bag produced from the composition obtained in Comparative Example 4
was broken when being dropped from 0.5 m height. On the other hand,
the bag produced from the composition obtained in Example 10 was
free from breakage even when being dropped from 2 m height.
Therefore, it was confirmed that the composition of the present
invention had a high impact strength.
1TABLE 1 Example 1 Example 2 Example 3 (A) component (wt %) 27.4
46.5 40.1 Cold xylene insolubles 27.2 46.2 39.9 (wt %) Cold xylene
solubles 0.2 0.3 0.2 (wt %) Isotactic Index (%) 98.8 98.1 98.6 (B)
component (wt %) 72.6 53.5 59.9 Cold xylene insolubles 32.8 23.4
34.3 (wt %) Cold xylene solubles 39.8 30.1 25.6 (wt %) Ethylene
content in 15.7 16.9 14.2 solubles (wt %) .alpha.t (wt %) -- -- --
CXS (wt %) -- -- -- 5.alpha.t-25 -- -- -- MFR (dg/min) 3.1 2.0 1.5
Density (g/cm.sup.3) 0.8863 0.8911 0.8923 Tensile strength at yield
11.8 14.6 16.4 point (MPa) Tensile strength at break 34.8 40.5 40.6
(MPa) Tensile elongation at 1,000 990 986 break (%) Flexural
modulus (MPa) 265 383 426 Flexural strength (MPa) 9.7 13.0 14.2
Izod (23.degree. C.) (kJ/m.sup.2) NB NB NB Izod (0.degree. C.)
(kJ/m.sup.2) NB NB NB Haze (%) 57.2 56.6 58.3 DSC melting peak
(.degree. C.) 163.8 164.7 164.2 Example 4 Example 5 Example 6 (A)
component (wt %) 33.6 37.5 25.9 Cold xylene insolubles 33.3 37.2
25.7 (wt %) Cold xylene solubles 0.3 0.3 0.2 (wt %) Isotactic Index
(%) 98.1 98.2 98.4 (B) component (wt %) 66.4 62.5 74.1 Cold xylene
insolubles 35.9 43.2 51.3 (wt %) Cold xylene solubles 30.5 19.3
22.8 (wt %) Ethylene content in 14.1 11.2 11.1 solubles (wt %)
.alpha.t (wt %) -- -- -- CXS (wt %) -- -- -- 5.alpha.t-25 -- -- --
MFR (dg/min) 1.6 2.7 2.5 Density (g/cm.sup.3) 0.8907 0.8955 0.8931
Tensile strength at yield 14.6 19.8 17.9 point (MPa) Tensile
strength at break 40.4 39.6 39.2 (MPa) Tensile elongation at 1,004
888 958 break (%) Flexural modulus (MPa) 350 551 465 Flexural
strength (MPa) 12.4 18.6 16.0 Izod (23.degree. C.) (kJ/m.sup.2) NB
NB NB Izod (0.degree. C.) (kJ/m.sup.2) NB 8.3 10.8 Haze (%) 53.1
64.2 61.0 DSC melting peak (.degree. C.) 164.2 163.8 163.8 Example
7 Example 8 Example 9 (A) component (wt %) 47.4 40.6 29.2 Cold
xylene insolubles 47.0 40.4 28.9 (wt %) Cold xylene solubles 0.4
0.2 0.3 (wt %) Isotactic Index (%) 98.3 98.6 98.5 (B) component (wt
%) 52.6 59.4 70.8 Cold xylene insolubles 22.8 24.9 25.3 (wt %) Cold
xylene solubles 29.8 34.5 45.5 (wt %) Ethylene content in 18.1 18.7
18.3 solubles (wt %) .alpha.t (wt %) 9.0 10.2 12.1 CXS (wt %) 30.2
34.7 45.8 5.alpha.t-25 20.0 26.0 35.5 MFR (dg/min) 2.6 1.6 1.4
Density (g/cm.sup.3) 0.8916 0.8892 0.8860 Tensile strength at yield
14.9 12.8 10.3 point (MPa) Tensile strength at break 38.4 36.0 33.7
(MPa) Tensile elongation at 976 941 989 break (%) Flexural modulus
(MPa) 403 318 212 Flexural strength (MPa) 13.7 11.0 8.5 Izod
(23.degree. C.) (kJ/m.sup.2) NB NB NB Izod (0.degree. C.)
(kJ/m.sup.2) NB NB NB Haze (%) 57.0 51.1 43.9 DSC melting peak
(.degree. C.) 164.7 164.2 164.2 Comparative Example 10 Example 11
Example 1 (A) component (wt %) 26.8 23.1 48.9 Cold xylene
insolubles 26.4 22.7 48.6 (wt %) Cold xylene solubles 0.4 0.4 0.3
(wt %) Isotactic Index (%) 98.2 98.4 98.1 (B) component (wt %) 73.2
76.9 51.1 Cold xylene insolubles 39.1 53 19.5 (wt %) Cold xylene
solubles 34.1 23.9 31.6 (wt %) Ethylene content in 14.6 11.5 22.2
solubles (wt %) .alpha.t (wt %) 10.1 8.5 -- CXS (wt %) 34.5 24.3 --
5.alpha.t-25 25.5 17.5 -- MFR (dg/min) 1.5 3.2 3.6 Density
(g/cm.sup.3) 0.8894 0.8928 0.8860 Tensile strength at yield 13.2
17.1 11.9 point (MPa) Tensile strength at break 38.1 38.6 31.7
(MPa) Tensile elongation at 985 968 948 break (%) Flexural modulus
(MPa) 290 432 354 Flexural strength (MPa) 10.7 15.1 10.9 Izod
(23.degree. C.) (kJ/m.sup.2) NB NB NB Izod (0.degree. C.)
(kJ/m.sup.2) NB 10.9 NB Haze (%) 48.3 60.1 82.9 DSC melting peak
(.degree. C.) 163.8 163.8 163.8 Comparative Comparative Example 2
Example 3 (A) component (wt %) 44.1 43.6 Cold xylene insolubles
43.8 42.8 (wt %) Cold xylene solubles 0.3 0.8 (wt %) Isotactic
Index (%) 98.1 98.3 (B) component (wt %) 55.9 56.4 Cold xylene
insolubles 21.5 10.8 (wt %) Cold xylene solubles 34.4 45.6 (wt %)
Ethylene content in 22.4 23.8 solubles (wt %) .alpha.t (wt %) 12.3
17.3 CXS (wt %) 34.7 46.4 5.alpha.t-25 36.5 61.5 MFR (dg/min) 2.8
2.1 Density (g/cm.sup.3) 0.8848 0.8820 Tensile strength at yield
10.7 10.1 point (MPa) Tensile strength at break 32.7 20.3 (MPa)
Tensile elongation at 949 870 break (%) Flexural modulus (MPa) 318
347 Flexural strength (MPa) 9.7 10.0 Izod (23.degree. C.)
(kJ/m.sup.2) NB NB Izod (0.degree. C.) (kJ/m.sup.2) NB NB Haze (%)
80.8 91.8 DSC melting peak (.degree. C.) 164.2 164.3 Comparative
Comparative Example 4 Example 5 (A) component (wt %) 8.3 52.6 Cold
xylene insolubles 8.1 47.8 (wt %) Cold xylene solubles 0.2 4.8 (wt
%) Isotactic Index (%) 96.5 92.3 (B) component (wt %) 91.7 47.4
Cold xylene insolubles 79.3 8.5 (wt %) Cold xylene solubles 12.4
38.9 (wt %) Ethylene content in 5.5 22.5 solubles (wt %) .alpha.t
(wt %) 5.5 11.8 CXS (wt %) 12.6 43.7 5.alpha.t-25 2.5 34.0 MFR
(dg/min) 3.1 2.2 Density (g/cm.sup.3) 0.8902 0.8835 Tensile
strength at yield 16.8 10.0 point (MPa) Tensile strength at break
30.7 26.0 (MPa) Tensile elongation at 840 890 break (%) Flexural
modulus (MPa) 482 320 Flexural strength (MPa) 17.8 11.0 Izod
(23.degree. C.) (kJ/m.sup.2) 14.5 NB Izod (0.degree. C.)
(kJ/m.sup.2) 3.7 NB Haze (%) 49.0 66.7 DSC melting peak (.degree.
C.) 134.6 152.5
[0115]
2 TABLE 2 Comparative Example 12 Example 6 Propylene-based
copolymer Example 10 Comparative composition Example 4 Haze before
A.C. sterilization (%) 12 15 Haze after A.C. sterilization (%) 14
21 Falling bag impact strength (m) >2 <0.5
* * * * *