Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-10-12
2001-07-03
Michl, Paul R. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
active
06255390
ABSTRACT:
TECHNICAL FIELD
This invention relates to a polyolefin type resinous composition which is superior in a transparency, a coloring property when pigment(s) being added and a dimensional stability.
BACKGROUND ART
Moldings made with use of polypropylenes (propylene homopolymer, ethylene-propylene copolymer, ethylene-propylene block copolymer) are relatively superior in an economical efficiency and have been used for wide fields. However, moldings made with use of propylene homopolymer have a high rigidity but have a disadvantage of a poor impact resistance, particularly a poor impact resistance at a low temperature. Thus, there have been hitherto made many propositions in order to improve an impact resistance at a low temperature.
In those propositions, propylene type block copolymers have been prepared generally by forming at first homopolymer components and then introducing ethylene-propylene random copolymer components. Since moldings made with use of propylene type block copolymers are superior in an impact resistance at a low temperature, they are used widely in various industrial fields such as automobiles and household electric appliances.
However, moldings made with use of conventional propylene type block copolymers are superior in an impact resistance but they have no transparency, thus they have such a disadvantage that they are not colored well when various pigments being added and they have such an additional disadvantage that a dimensional stability is bad.
DISCLOSURE OF THE INVENTION
We inventors made extensive researches with an object to solve the above-mentioned problems, to attain a polyolefin type resinous composition which is superior in a transparency, a coloring property when pigment(s) being added and a dimensional stability by controlling a product of a polymerization forming ratio of a homopolymer component to a copolymer component and a respective limiting viscosity ratio within a specified range, furthermore controlling a ratio of a melt flow rate of a homopolymer component to a melt flow rate of an ethylene-propylene copolymer component, and furthermore controlling a ratio of a melt flow rate of the homopolymer component in the propylene type block copolymer composition [A] to a melt flow rate of the olefin type or styrene type elastomer ([MFR]
R
/[MFR]
PP
) as well as a ratio of a limiting viscosity of the homopolymer component in the propylene type block copolymer composition [A] to a limiting viscosity of the olefin type or styrene type elastomer ([&eegr;]
R
/[&eegr;]
PP
) in a propylene type block copolymer composition [A] obtained by forming a homopolymer in gaseous phase polymerization and thereafter polymerizing an ethylene-propylene copolymer component.
As clear from the above-mentioned explanation, the object of the present invention is to provide a polyolefin type resinous composition which is superior in a transparency, a coloring property when pigment(s) being added and a dimensional stability.
The present invention has the following constructions.
(1) A polyolefin type resinous composition comprising 99~80% by weight of a propylene type block copolymer [A] wherein the said block copolymer consists of a propylene homopolymer component and an ethylene-propylene copolymer component, a product of a limiting viscosity ratio of the said copolymer component to the said homopolymer component and a weight ratio of the said homopolymer component to the said copolymer component is within a range of
(([&eegr;]
RC
/[&eegr;]
PP
)×(
W
PP
/W
RC
))=0.2~3.0,
wherein a limiting viscosity of the said homopolymer component being [&eegr;]
PP
, a limiting viscosity of the said copolymer component being [&eegr;]
RC
, a weight of the said homopolymer component being W
PP
and a weight of the said copolymer component being W
RC
, as well as a ratio of a melt flow rate of the said homopolymer component to a melt flow rate of the said copolymer component is within a range of
([
MFR]
RC
/[MFR]
PP
)=0.3~4.0,
a ratio of a limiting viscosity in the said homopolymer component to the said copolymer component is within a range of
[&eegr;]
RC
/[&eegr;]
PP
=0.7~1.2,
and [&eegr;]
RC
of the said copolymer component is 6.5 or less, and 1~20% by weight of an ethylene type or styrene type elastomer [B] wherein a ratio of a melt flow rate of the homopolymer component in the said propylene type block copolymer [A] to a melt flow rate of the latter mentioned olefin type or styrene type elastomer is within a range of
([
MFR]
R
/[MFR]
PP
)=0.3~4,
and a ratio of a limiting viscosity [&eegr;]
PP
in the homopolymer component in the said propylene type block copolymer [A] to a limiting viscosity of the latter mentioned olefin type or styrene type elastomer [&eegr;]
R
is within a range of
[&eegr;]
R
/[&eegr;]
PP
=0.7~1.2.
(2) A polyolefin type resinous composition according to the above-mentioned (1) wherein the copolymer component in the propylene type block copolymer (A) contains an ethylene weight unitof 25~55% by weight based on the copolymer component weight.
(3) A polyolefin type resinous composition according to the above-mentioned (1) wherein the propylene type block copolymer (A) contains a copolymer component of 22~70% by weight based on the weight.
(4) A polyolefin type resinous composition according to the above-mentioned (1) wherein the olefin type or styrene type elastomer [B] is ethylene-butene rubber.
(5) A polyolefin type resinous composition comprising 100 parts by weight of the polyolefin type resinous composition according to the above-mentioned (1) to (4) and 0.001~0.1 parts by weight of a molecular weight decreasing agent (C).
BEST MODE FOR CARRYING OUT THE INVENTION
The invention is illustrated as follows.
Necessary conditions of the propylene type block copolymer composition [A] used in the invention are that a relationship formula between contents and respective limiting viscosities in the homopolymer component and the copolymer component ([&eegr;]
RC
/[&eegr;]
PP
)×(W
PP
/W
RC
) is within a range of 0.2~3.0, more preferably 0.3~2.7, that a ratio of a melt flow rate of the said homopolymer component to a melt flow rate of the said copolymer component. ([MFR]
RC
/[MFR]
PP
) is within a range of 0.3~4, more preferably 0.3~3.5, that a limiting viscosity of the copolymer component [&eegr;]
RC
is 6.5 or less, more preferably 5.0 or less, and that a ratio of a limiting viscosity ratio of the homopolymer component to a limiting viscosity of the copolymer component, [&eegr;]
ER
/[&eegr;]
PP
, is within a range of 0.7~1.2, preferably 0.8~1.2.
Furthermore, the olefin type or styrene type elastomer has a ratio of a melt flow rate of the homopolymer component in the propylene type block copolymer composition [A] to a melt flow rate of the olefin type or styrene type elastomer ([MFR]
R
/[MFR]
PP
) is within a range of 0.3~4, more preferably 0.3~3.5, and a ratio of a limiting viscosity ratio of the homopolymer component of the propylene type block copolymer composition [A] to a limiting viscosity of the olefin type or styrene type elastomer ([&eegr;]
R
/[&eegr;]
PP
) is within a range of 0.3~4, more preferably 0.3~3.5, from a viewpoint of a transparency in the obtained resinous composition.
A copolymer component content of the said propylene type block copolymer composition [A] is preferably within a range of 22~70% by weight, more preferably 23~55% by weight, from viewpoints of a transparency and dimensional a stability in the obtained resinous composition as well as from an economical viewpoint due to superior flowability in the formed powders during preparation of the said propylene type block copolymer compositio
Enomoto Takehiko
Okayama Chikashi
Chisso Corporation
McDermott & Will & Emery
Michl Paul R.
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