Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-08-31
2002-07-09
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...
C526S124200, C526S127000, C526S160000, C526S943000, C502S117000, C502S152000
Reexamination Certificate
active
06417299
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a process for producing ethylene/olefin interpolymers, which for a given melt index (MI) and density, have reduced melting peak temperatures (T
m
). Melting peak temperature (T
m
) is alternatively referred to as melt transition temperature or melting point. The present invention also relates to a process for reducing the melting peak temperature (T
m
) of ethylene/olefin interpolymers having a given melt index and density. Additionally, this invention relates to novel ethylene/olefin interpolymers, and films and articles of manufacture produced therefrom.
BACKGROUND OF INVENTION
Polyethylene and interpolymers of ethylene are well known and are useful in many applications. In particular linear interpolymers of ethylene, also known as copolymers, terpolymers, and the like of ethylene, possess properties which distinguish them from other polyethylene polymers, such as branched ethylene homopolymers commonly referred to as LDPE (low density polyethylene). Certain of these properties are described by Anderson et al, U.S. Pat. No. 4,076,698.
A particularly useful polymerization medium for producing polymers and interpolymers of ethylene is a gas phase process. Examples of such are given in U.S. Pat. Nos. 3,709,853; 4,003,712; 4,011,382; 4,302,566; 4,543,399; 4,882,400; 5,352,749 and 5,541,270 and Canadian Patent No. 991,798 and Belgian Patent No. 839,380.
There are known various catalysts for polymerizing and interpolymerizing ethylene. Exemplary of such catalysts are as follow:
1. Chromium oxide catalysts which polymerize ethylene to high molecular weight high density polyethylenes (HDPE) having a broad molecular weight distribution. These catalysts are typically based on Cr(6+) and are supported on a carrier.
2. Organochromium catalysts such as bis(triphenylsilyl)chromate supported on silica and activated with organoaluminum compounds, and bis(cyclopentadienyl)chromium supported on silica.
3. Ziegler-Natta catalysts which typically consist of a transition metal component and an organometallic co-catalyst that is typically an organoaluminum compound.
4. An olefin polymerization catalyst that polymerizes olefins to produce homopolymers and interpolymers of olefins having a molecular weight distribution (MWD) of from 1 to 2.5.
5. Metallocene catalysts which typically consist of a transition metal having at least one substituted or unsubstituted cyclopentadienyl or cyclopentadienyl moiety, and an organometallic co-catalyst that is typically alkyl aluminoxane, such as methyl aluminoxane, or an aryl substituted boron compound.
6. Group 13 catalysts of the type described in U.S. Pat. No. 5,777,120, such as cationic aluminum alkyl amidinate complexes with an organometallic co-catalyst that is typically alkylaluminoxane, such as methylaluminoxane, or an aryl substituted boron compound.
7. Catalysts of the type described in U.S. Pat. No. 5,866,663, such as cationic nickel alkyl diimine complexes with an organometallic co-catalyst that is typically alkylaluminoxane, such as methylaluminoxane, or an aryl substituted boron compound.
8. Catalysts of the type described in Organometallics, 1998, Volume 17, pages 3149-3151, such as neutral nickel alkyl salicylaldiminato complexes.
9. Catalysts of the type described in the Journal of the American Chemical Society, 1998, Volume 120, pages 7143-7144, such as cationic iron alkyl pyridinebisimine complexes with an organometallic co-catalyst that is typically alkylaluminoxane, such as methylaluminoxane, or an aryl substituted boron compound.
10. Catalysts of the type described in the Journal of the American Chemical Society, 1996, Volume 118, pages 10008-10009, such as cationic titanium alkyl diamide complexes with an organometallic co-catalyst that is typically alkylaluminoxane, such as methylaluminoxane, or an aryl substituted boron compound.
The above catalysts are, or can be, supported on an inert porous particulate carrier.
It is also well known in the polymerization of olefins, particularly where Ziegler-Natta catalysts are employed, to utilize, optionally, electron donors. Such electron donors often aid in increasing the efficiency of the catalyst and/or in controlling the stereospecificity of the polymer when an olefin, other than ethylene, is polymerized. Electron donors when employed during the catalyst preparation step are referred to as internal electron donors. Electron donors when utilized other than during the catalyst preparation step are referred to as external electron donors. For example, the external electron donor may be added to the preformed catalyst, to the prepolymer, and/or to the polymerization medium.
The use of electron donors in the field of propylene polymerization is well known and is primarily used to reduce the atactic form of the polymer and increase the production of the isotactic polymers. The use of electron donors generally improves the productivity of the catalyst in the production of isotactic polypropylene. This is shown generally in U.S. Pat. No. 4,981,930. It is also known to utilize electron donors to control molecular weight and molecular weight distribution of polypropylene. The result of increasing the stereoregularity, either the isotactic or syndiotactic content, of polypropylene is to increase the crystallinity of the polymer which generally correlates to an increase in the melting peak temperature (T
m
). This is shown generally in U.S. Pat. Nos. 5,710,222 and 5,688,735.
The concept of stereoregularity is not relevant in the field of ethylene interpolymerization where ethylene constitutes at least about 50% by weight of the total monomers present in the polymer. See for example U.S. Pat. No. 5,055,535. In ethylene polymerization electron donors are utilized to control the molecular weight distribution (MWD) of the polymer and the activity of the catalyst in the polymerization medium. Exemplary patents describing the use of internal electron donors in producing polyethylene are U.S. Pat. Nos. 3,917,575; 4,187,385, 4,256,866; 4,293,673; 4,296,223; Reissue 33,683; 4,302,565; 4,302,566; and 5,470,812. Exemplary patents describing the use of external electron donors in producing polyethylene are U.S. Pat. Nos. 4,234,710; 4,287,328; 5,055,535 and 5,192,729.
U.S. Pat. No. 5,399,638 discloses the use of a morphology protector obtained by reacting alkylaluminum with an electron donor during a prepolymerization step to maintain the morphology of the support and the catalytic component on the prepolymerized support. Also disclosed is the use of the alkylaluminum electron donor complex to increase the effectiveness of the comonomer in reducing the density of the interpolymer in the case of interpolymerization.
U.S. Pat. No. 5,055,535 discloses the use of an external monoether electron donor, such as tetrahydrofuran (THF), to control molecular weight distribution.
U.S. Pat. No. 5,244,987 and 5,410,002 disclose the use of external electron donors to control the reactivity of catalyst particles in the polymerization reactor.
U.S. Pat. No. 4,652,540 discloses the use of carbonyl sulfide to reduce the adverse effect on polymerization activity resulting from poison impurities contained in the olefin feed streams.
The use of internal electron donors with metallocene catalysts is disclosed in U.S. Pat. No. 5,106,804. The use of external electron donors with metallocene catalysts to control molecular weight is disclosed in U.S. Pat. No. 5,883,203.
Illustrative examples of electron donors include carboxylic acids, carboxylic acid esters, alcohols, ethers, ketones, amines, amides, nitrites, aldehydes, thioethers, thioesters, carbonic esters, organosilicon compounds containing at least one oxygen atom, and nitrogen, phosphorus, arsenic or antimony compounds connected to an organic group through a carbon or oxygen atom.
SUMMARY OF THE INVENTION
Applicants have unexpectedly found that the addition of at least one compound comprising at least one element from Group 15 and/or Group 16 of the Periodic Table of Elements, herein referred to as a modifier, in a process for pr
Ford Randal Ray
Vanderbilt Jeffrey James
Williams Darryl Stephen
Chaletsky Lawrence A.
Eastman Chemical Company
Graves, Jr. Bernard J.
Harlan R.
Wood Jonathan D.
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