Crystalline polypropylenes, process for preparing thereof,...

Details Crystalline polypropylenes, process for preparing thereof,... Crystalline polypropylenes, process for preparing thereof,...

1998-11-25

2002-06-11

Mullis, Jeffrey (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C526S086000, C526S087000

Reexamination Certificate

active

06403708

ABSTRACT:

FIELD OF THE ART
The present invention concerns crystalline polypropylenes, that are especially excellent in hardness and rigidity, high in melt tension, and have excellent molding properties, process for preparing such polypropylenes, and compositions and thermoformed products obtained from such polypropylenes.
BACKGROUND ART
Crystalline polypropylenes are excellent in hardness, rigidity, heat resistance, surface gloss (luster), etc., and have been conventionally used in various applications. In particular, crystalline polypropylenes are used in automobile bumpers, etc., that require high rigidity.
Such crystalline polypropylenes are used upon blending various modifiers according to the application, and are generally blended with an impact resistance modifier, such as polyethylene, rubber material, etc.
Previously, in order to compensate for the lowering of rigidity that accompanies the addition of the impact resistance modifier, an inorganic filler, such as talc, has been added.
However, there is a limit to the rigidity improvement effect that can be provided by the addition of an inorganic filler, and for example in systems using a large amount of impact resistance modifiers, it was difficult to obtain a polypropylene resin composition of adequately high rigidity even upon addition of an inorganic filler.
Polypropylene resins that are even more improved in rigidity were thus desired especially in thermoformed product applications requiring hardness and high rigidity.
It is known that the rigidity of polypropylene can be improved by raising its crystallinity (stereoregularity), and it is also considered that the rigidity of polypropylene is so desired that the wider molecular weight distribution (Mw/Mn) of the crystalline components (components insoluble in 64° C. decane) contained in the polypropylene is obtained.
The present inventors also carried out research toward improvement of the rigidity of polypropylene, and found that even if a crystalline polypropylene contains components insoluble in 64° C. decane of a wide molecular weight distribution (Mw/Mn), the polypropylene cannot always be sufficiently satisfactory in rigidity, elongation, and toughness if the polypropylene has a wide molecular weight distribution in both the high molecular weight side and low molecular weight side. The present inventor then found that crystalline polypropylenes and polypropylene compositions containing crystalline components (components insoluble in 64° C. decane), which not only have a wide molecular weight distribution (Mw/Mn) but also have a wide molecular weight distribution (Mz/Mw), as determined from the z-average molecular weight and weight-average molecular weight of said components insoluble in decane, of 5 or more, and which have a pentad isotacticity of 98% or more, and for which the frequency dependence value D of the viscoelastic loss tangent under constant strain is 4.0 or more, are extremely excellent in rigidity, and has thereby been led to complete the present invention.
Polypropylenes of wide molecular weight distribution have been proposed previously, and for example in Japanese laid-open patent publication No. 59-172507 is disclosed the production of a polypropylene (PP) by two-stage polymerization to produce a high molecular weight component (35 to 65 wt. % of polypropylene of (&eegr;)=1.8 to 10 dl/g in the first stage) and a low molecular weight component (65 to 35 wt. % of polypropylene of (&eegr;)=0.6 to 1.2dl/g in the second stage), and then finally to produce polypropylene of (&eegr;)=1.2 to 7 dl/g and Mw/Mn of 6 to 20. Also, in Japanese laid-open patent publication No. 4-370103 is disclosed the production of a high molecular weight component having MFR=0.0001 to 10 g/10 minutes in the stage of producing the component of highest molecular weight in multiple-stage polymerization and a low molecular weight component of MFR=10 to 100 g/10 minutes in the stage producing the low molecular weight component. In Japanese laid-open patent publication No. 8-3223 are disclosed polypropylenes having Mw=1.2 to 2 million, Mw/Mn of 30 to 70, and containing 7 to 15 wt. % of a high molecular weight component of Mw≧5 million and 20 to 50 wt. % of a low molecular weight component of Mw<100 thousand.
However the polypropylenes that are disclosed in these patent publications all have a wide distribution both in the high molecular weight side and low molecular weight side and such polypropylenes cannot always be sufficiently satisfactory in rigidity, elongation, and toughness as mentioned above.
In Japanese laid-open patent publication No. 4-202507 is disclosed a process of producing PP by polymerizing a PP component (0.1 to 35 wt. %) of (&eegr;)=5 to 40 dl/g using a prepolymerized catalyst and then polymerizing the remaining PP components in another polymerizer to obtain PP having MFR=0.1 to 2000 g/10 minutes. In Japanese patent publication No. 7-5668 is disclosed highly crystalline polypropylenes having an MFR of 0.1 to 200 g/10 minutes with which the MFR value and the ratio of absorbance at 997cm
−1
and 973 cm
−1
(997 cm
−1
/973 cm
−1
) in the IR spectrum satisfy specific relationships, said IR absorbance ratio of the initial precipitate component, that comprises 2 to 3 wt. % of the total amount dissolved when the polypropylene is dissolved in xylene, is 0.97 or more, and the Mw of said precipitate component/Mw of total PP is 3 or more.
Although the above patent publications disclose polypropylenes that contain high molecular weight components, none of the publications disclose the widening of the molecular weight distribution at the high molecular weight side without widening the molecular weight distribution at the low molecular weight side.
DISCLOSURE OF THE INVENTION
The crystalline polypropylenes of the present invention are characterized in containing components insoluble in 64° C. decane that satisfy the following characteristics (1) to (4):
(1) The intrinsic viscosity (&eegr;) (in 135° C. decalin) is 0.5 to 10 dl/g;
(2) the molecular weight distribution (Mz/Mw) as determined by gel permeation chromatography (GPC; solvent: o-chlorobenzene, measurement temperature: 140° C.) is 5 or more;
(3) the pentad isotacticity (mmmm percentage), which is a stereoregularity index determined by the measurement of the
13
C-NMR spectrum, is 98% or more; and
(4) the D value, determined using formula (1) below from the loss tangents, tan &dgr;
0.05
and tan &dgr;
10
measured at the frequencies, 0.05 rad/sec and 10 rad/sec, respectively, by a melt viscoelasticity measuring device under a temperature of 230° C. and constant strain, and said loss tangent measurement frequencies, is 4.0 or more.
D
=
&LeftBracketingBar;
log
⁡
(
0.05
)
-
log
⁡
(
10
)
log
⁡
(
tan
⁢
 
⁢
δ
0.05
)
-
log
⁡
(
tan
⁢
 
⁢
δ
10
)
&RightBracketingBar;
(
1
)
It is preferable for the number-average molecular weight Mn of the components insoluble in 64° C. decane to be 25000 or more.
It is preferable for the crystalline polypropylene of the present invention to contain 60 wt. % (% by weight) or more of the above-described components insoluble in 64° C. decane.
It is preferable for the crystalline polymer to contain a prepolymer as a nucleating agent.
The abovementioned polypropylene may specifically be a homopolypropylene or a propylene block copolymer.
The crystalline polypropylene can be produced by multiple-stage polymerization of propylene, optionally, along with another monomer in the presence of a catalyst for preparing highly stereoregular polypropylene.
In the present invention, it is preferable to perform the abovementioned multiple-stage polymerization in three stages, wherein in the first stage crystalline polypropylene having an intrinsic viscosity (&eegr;) of 8 to 20 dl/g is produced at an amount corresponding to 0.5 to 15 wt. % of the finally obtained crystalline polypropylene,
in the second stage crystalline polypropylene having an intrinsic viscosity (&eegr;) of 3 to 10 dl/g is

Affiliated with

Also associated with

Rating

Crystalline polypropylenes, process for preparing thereof,... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Crystalline polypropylenes, process for preparing thereof,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Crystalline polypropylenes, process for preparing thereof,... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2959838