Branched polypropylene compositions

Details Branched polypropylene compositions Branched polypropylene compositions

1999-08-17

2001-05-01

Wu, David W. (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S127000, C526S160000, C526S170000, C526S155000, C502S152000

Reexamination Certificate

active

06225432

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to branched polypropylene compositions and a method for the preparation of branched polypropylene utilizing single site catalyst compounds.
BACKGROUND OF THE INVENTION
Polypropylene and related polymers are known to have low melt strength. This is a significant deficiency in key application areas such as thermoforming, foaming, and blow molding. Polyethylene on the other hand is used extensively in blown film applications requiring good melt strength. The limitations in the melt strength of polypropylenes show up as excess sag in sheet extrusion, rapid thinning of walls in parts thermoformed in the melt phase, low draw-down ratios in extrusion coating, poor bubble formation in extrusion foam materials, and relative weakness in large-part blow molding. Thus, it would be highly desirable to produce polypropylene and related polymers having enhanced melt strength as well as commercially valuable processability.
Increasing the melt strength of polymers such as polypropylene has been an industrial goal for well over ten years. However, success has been limited. The desirable properties that have made low density polyethylene commercially successful are attributed in large part to high melt strength and excellent processability. Both of these properties are attributed to the presence of long chain branching, which is thought to occur under high pressure polymerization conditions.
There has been some success in increasing the melt strength of polypropylene. For example, EP 190 889 A2 discloses high energy irradiation of polypropylene to create what is believed to be polypropylene having substantial free-end long branches of propylene units. EP 384 431 discloses the use of peroxide decomposition of polypropylene in the substantial absence of oxygen to obtain a similar product.
Other attempts to improve the melt properties of polypropylene include U.S. Pat. No. 5,441,236, which introduces long chain branching by bridging two PP backbones to form H-type polymers, and U.S. Pat. No. 5,514,761, which uses dienes incorporated in the backbones to achieve a similar effect. However, cross-linking and gel formation can occur in such processes. In addition, these techniques introduce additional process steps which result in a more complex and expensive process.
Thus, there is still a need for propylene polymers having improved melt strength and good processability which can be produced efficiently.
SUMMARY OF THE INVENTION
The present invention meets that need by providing branched polypropylene compositions which have improved melt strength and good processability. The branched polypropylene compositions of the present invention have a polydispersity of less than or equal 4.0, and a melting point greater than 90° C. Further, the weight average branching index, g, of the polypropylene compositions is less than 0.95. Additionally, a novel process is provided for efficiently producing a branched polypropylene composition comprising:
a) contacting propylene monomers in a reactor with an inert hydrocarbon solvent or diluent and a catalyst composition comprising one or more single site catalyst compounds capable of producing stereospecific polypropylene at a temperature from about 40° C. to about 120° C., wherein the ratio in the reactor of the propylene monomers to the inert hydrocarbon solvent or diluent is less than 9.0, and further, wherein the propylene monomers and the inert hydrocarbon solvent or diluent comprise at least 50 percent of the total contents of the reactor; and
b) recovering a branched polypropylene composition having a polydispersity of less than or equal to 4.0 and a melting point greater than 90° C. wherein the weight average branching index, g, of the branched polypropylene composition is less than 0.95.


REFERENCES:
patent: 4530914 (1985-07-01), Ewen et al.
patent: 4542199 (1985-09-01), Kaminsky et al.
patent: 4543399 (1985-09-01), Jenkins, III et al.
patent: 4588790 (1986-05-01), Jenkins, III et al.
patent: 4665208 (1987-05-01), Welborn, Jr. et al.
patent: 4701432 (1987-10-01), Welborn, Jr.
patent: 4808561 (1989-02-01), Welborn, Jr.
patent: 4874734 (1989-10-01), Kioka et al.
patent: 4892851 (1990-01-01), Ewen et al.
patent: 4908463 (1990-03-01), Bottelberghe
patent: 4921825 (1990-05-01), Kioka et al.
patent: 4923833 (1990-05-01), Kioka et al.
patent: 4924018 (1990-05-01), Bottelberghe
patent: 4933403 (1990-06-01), Kaminsky et al.
patent: 4937299 (1990-06-01), Ewen et al.
patent: 4952540 (1990-08-01), Kioka et al.
patent: 4968827 (1990-11-01), Davis
patent: 5017714 (1991-05-01), Welborn, Jr.
patent: 5028670 (1991-07-01), Chinh et al.
patent: 5057475 (1991-10-01), Canich et al.
patent: 5091352 (1992-02-01), Kioka et al.
patent: 5103031 (1992-04-01), Smith, Jr.
patent: 5120867 (1992-06-01), Welborn, Jr.
patent: 5132381 (1992-07-01), Winter et al.
patent: 5149819 (1992-09-01), Satoh et al.
patent: 5155080 (1992-10-01), Elder et al.
patent: 5157137 (1992-10-01), Sangokoya
patent: 5198401 (1993-03-01), Turner et al.
patent: 5204419 (1993-04-01), Tsutsui et al.
patent: 5206199 (1993-04-01), Kioka et al.
patent: 5235081 (1993-08-01), Sangokoya
patent: 5239022 (1993-08-01), Winter et al.
patent: 5240894 (1993-08-01), Burkhardt et al.
patent: 5243001 (1993-09-01), Winter et al.
patent: 5248801 (1993-09-01), Sangokoya
patent: 5276208 (1994-01-01), Winter et al.
patent: 5278119 (1994-01-01), Turner et al.
patent: 5296434 (1994-03-01), Karl et al.
patent: 5304614 (1994-04-01), Winter et al.
patent: 5308815 (1994-05-01), Sangokoya
patent: 5318935 (1994-06-01), Canich et al.
patent: 5324800 (1994-06-01), Welborn, Jr. et al.
patent: 5328969 (1994-07-01), Winter et al.
patent: 5329032 (1994-07-01), Tran et al.
patent: 5350723 (1994-09-01), Neithamer et al.
patent: 5352749 (1994-10-01), DeChellis et al.
patent: 5391790 (1995-02-01), Rohrmann et al.
patent: 5405922 (1995-04-01), DeChellis et al.
patent: 5436304 (1995-07-01), Griffin et al.
patent: 5514761 (1996-05-01), Etherton et al.
patent: 5541236 (1996-07-01), DeNicola, Jr. et al.
patent: 5705584 (1998-01-01), Fukuoka et al.
patent: 5945367 (1999-08-01), Thiele et al.
patent: 2241812 (1997-04-01), None
patent: 0 190 889 (1986-08-01), None
patent: 0 190 889 A2 (1986-08-01), None
patent: 0 277 004 (1988-08-01), None
patent: 0 277 003 (1988-08-01), None
patent: 0 320 762 (1989-06-01), None
patent: 0 426 637 (1991-05-01), None
patent: 0 495 375 (1992-07-01), None
patent: 0 500 944 (1992-09-01), None
patent: 0 279 863 (1992-10-01), None
patent: 0 520 732 (1992-12-01), None
patent: 0 561 476 (1993-09-01), None
patent: 0 570 982 (1993-11-01), None
patent: 0 573 403 (1993-12-01), None
patent: 0 594 218 (1994-04-01), None
patent: 0 279 586 (1994-05-01), None
patent: 0 354 893 (1994-11-01), None
patent: 0 384 431 (1994-11-01), None
patent: 0 678 527 A2 (1995-10-01), None
patent: 0 718 324 A2 (1996-06-01), None
patent: WO 91/09882 (1991-07-01), None
patent: WO 92/00333 (1992-01-01), None
patent: WO 94/03506 (1994-02-01), None
patent: WO 94/07930 (1994-04-01), None
patent: WO 94/07928 (1994-04-01), None
patent: WO 94/10180 (1994-05-01), None
patent: WO 94/28034 (1994-12-01), None
patent: WO 96/00245 (1996-01-01), None
patent: WO 96/00243 (1996-01-01), None
patent: WO 96/04319 (1996-02-01), None
patent: WO 97/02276 (1997-01-01), None
patent: WO 97/11775 (1997-04-01), None
Scollard, et al, Sterically Demanding Diamide Ligands: Synthesis of Structure of d° Zirconium Alkyl Derivatives,Organometallics, v. 14, pp.5478-5480, (1995).
Repo, et al, Metallocene Dichlorides Bearing Acenaphthyl Substitued Cyclopentadienyl Rings: Preparation and Polymerization Behavior,Journal of Organometallic Chemistry, v.549, pp. 177-186, (1997).
vol. 1,Experimental Methods in Catalyst Research, Academic Press (1968), pp. 67-99.
Britovsek, et al, “Novel Olefin Polymerization Catalysts Based on Iron and Cobalt”—Chem. Commun., (1998), pp. 849-850.
Johnson, et al, “New PD(II)-and Ni(II)-Based Catalysts for Polymerization of Ethylene and &agr;Olefins”—J. American Chem Soc, v.117 (1995), pp. 6414-6415.
Small, et al, “Highly Activ

Affiliated with

Also associated with

Rating

Branched polypropylene compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Branched polypropylene compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Branched polypropylene compositions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2489598