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
2000-05-18
2001-07-24
Teskin, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S184000, C525S186000, C525S189000, C525S190000, C525S245000, C525S279000, C525S289000, C525S296000, C525S301000, C525S310000, C525S313000, C525S319000, C525S320000, C525S322000, C525S324000, C525S332200, C525S360000, C525S384000, C525S385000, C525S386000, C526S336000
Reexamination Certificate
active
06265493
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a process for preparing polyolefin graft copolymers containing polyolefin backbone and pendant polymer side chains derived from both chain and step growth polymerization reactions. The process includes functionalization and graft copolymerization reactions utilizing linear copolymers of alpha-olefins and divinylbenzene, which have been prepared using certain metallocene catalysts, which have narrow molecular weight and composition distributions, and which range from semicrystalline thermoplastics to amorphous elastomers, to form olefin/divinylbenzene copolymers having pendant styrene units.
BACKGROUND OF THE INVENTION
Although useful in many commercial applications, polyolefin homopolymers, such as high density polyethylene (HDPE) and isotactic polypropylene (i-PP), suffer poor interaction with other materials. The inert nature of polyolefins significantly limits their end uses, particularly those in which adhesion, dyeability, paintability, printability or compatibility with other functional polymers is paramount.
Unfortunately, because of their inert nature and crystallinity, polyolefins have been among the more difficult materials to chemically modify by means of post-polymerization processes. In many cases, the post-polymerization reactions result in serious side reactions, such as degradation and crosslinking reactions. Although the direct copolymerization is the most effective route to functionalize polyolefins, such direct processes usually are laden with difficulties and limitations.
Only the transition metal coordination catalysts (Ziegler-Natta and metallocene catalysts) can be used in the preparation of linear polyolefins, and it normally is difficult to incorporate functional group-containing monomers into the polyolefins by using the early transition metal catalysts due to catalyst poisoning (see J. Boor, Jr.,
Ziegler-Naaa Catalysts and Polymerizations
, Academic Press, New York, 1979). The Lewis acid components (Ti, V, Zr and Al) of the catalyst will tend to complex with nonbonded electron pairs on N, O, and X (halides) of functional monomers in preference to complexation with the electrons of the double bonds. The net result is the deactivation of the active sites by formation of stable complexes between catalysts and functional groups, thus inhibiting polymerization.
In several prior art disclosures, it has been taught to prepare reactive polyolefin copolymers containing either borane (see U.S. Pat. Nos. 4,734,472; 4,751,276; 4,812,529; 4,877,846) or p-methylstyrene (see U.S. Pat. Nos. 5,543,484; 5,866,659 and 6,015,862; and
J. Polym. Sci. Polym Chem.,
36, 1017, 1998;
J. Polym. Sci. Polym Chem.,
37, 2795, 1999; and
Macromolecules,
31, 2028, 1998) reactive comonomer units. The chemistry disclosed in this prior art involves the direct copolymerization of alpha-olefins and organoborane-substituted monomers and p-methylstyrene, respectively, with Ziegler-Natta and metallocene catalysts. The homo- and copolymers containing reactive borane or p-methylstyrene groups are very useful intermediates for preparing a series of functionalized polyolefins. Many new functionized polyolefins with various molecular architectures have been obtained based on this chemistry. In addition, it has been demonstrated that polar groups can improve the adhesion of polyolefins to many substrates, such as metals and glass (see Chung et al,
J. Thermoplastic Composite Materials,
6, 18, 1993 and
Polymer,
35, 2980, 1994). The application of both borane-containing polymers and p-methylstyrene-containing polymers also has been extended to the preparation of polyolefin graft copolymers, which involves free radical (see U.S. Pat. Nos. 5,286,800 and 5,401,805; Chung et al,
Macromolecules,
26, 3467, 1993; and Chung et al,
Macromolecules,
32, 2525, 1999) and anionic graft-from reactions (see Chung et al,
Macromolecules,
30, 1272, 1997), respectively. In polymer blends, compatibility of the polymers can be improved by adding a suitable polyolefin graft copolymer which reduces the domain sizes and increases the interfacial interaction between domains.
Another approach toward preparing functionalized polyolefins is the preparation of unsaturated polyolefin copolymers containing pending unsaturated side chains which are reactive in subsequent chemical functionalization reactions. In general, the transition metal (Ziegler-Natta and metallocene catalysts) copolymerization of alpha-olefin and diene monomer is a great concern with many potential side reactions. The diene monomer, containing two reactive sites, potentially may engage in a double addition reaction to form copolymers having long branching side chains or even three dimensional network (crosslinked) structures. Most of linear diene-containing copolymers that have been reported involve the use of asymmetric dienes (see U.S. Pat. Nos. 3,658,770; 4,680,318; and 4,366,296) which contain only one polymerizable olefin unit, either an alpha-olefin or a constrained cyclolefin moiety, to prevent the formation of crosslinked (unprocessible) products. The asymetric dienes include those containing an alpha-olefin unit and an internal olefin unit, such as 1,4-hexadiene and methyl-1,4-hexadiene, and those containing a constrained cycloolefin unit and a linear olefin unit, such as 2-methylene-5-norborene, 5-vinyl-2-norborene and dicyclopentadiene. Several unsaturated polyolefins have been reported, including unsaturated polyethylene copolymers (Marathe et al.
Macromolecules,
27, 1083, 1994), polypropylene copolymers (Kitagawa et al.,
Polymer Bulletin,
10, 109, 1983) and ethylene-propylene terpolymers (VerStrate et al,
Encyclopedia of Polym. Sci. and Eng.,
6, 522, 1986). Recently, Machida et al. (JP 05-194665 and JP 05-194666) also reported the copolymerization of alpha-olefins and asymetric styrenic diene comonomers, such as p-(3-butenyl)styrene, to produce linear copolymers using Ziegler-Natta heterogeneous catalysts.
Alpha-olefin polymerization involving symmetric alpha,omega-diene comonomers in which both double bonds are terminal alpha-olefins are very limited. One such polymerization, which involved the copolymerization of alpha-olefin and 1,3-butadiene (Bruzzone et al.,
Makromol. Chem.,
179, 2173, 1978; Cucinella et al.,
European Polym. J.,
12, 65, 1976), resulted in copolymers where the butadiene units in the copolymer were mostly in the trans-1,4-configuration. In other words, both alpha-olefins in the butadiene monomer were engaged in the polymerization reaction. Some diene comonomers having a long spacer between two terminal olefins, including C
8
-C
14
aliphatic alpha,omega-dienes, such as 1,7-octadiene, 1,9-decadiene, 1,11-dodecadiene and 1,13-tetradecadiene (see U.S. Pat. Nos. 4,551,503; 4,340,705; and 5,504,171), were found to be more selective so as to engage only one olefin group in the heterogeneous Ziegler-Natta copolymerization reaction. The resulting polyolefin copolymers have pending alpha-olefin groups located along the polymer chain.
Incorporating divinylbenzene (a symmetric alpha,omega-diene) comonomer into a linear polyolefin would result in polyolefin copolymers containing pending styrene groups, as illustrated below in Formula (I). Such copolymers could be used as versatile precursors for a broad range of polyolefin structures, including the polyolefin graft copolymers containing polyolefin backbone and other polymer side chains. However, it is very difficult to prepare linear polyolefin copolymers having a well-defined molecular structure, as illustrated in Formula (I), due to potential branching and crosslinking reactions, resulting from the difuntional nature of divinylbenzene.
The transition metal copolymerization of styrenic monomers and alpha-olefins usually is very difficult to accomplish (see Seppala et al.,
Macromolecules,
27, 3136, 1994 and Soga et al.,
Macromolecules,
22, 2875, 1989). This is especially true when using stereospecific heterogeneous Ziegler-Natta catalysts having multiple active sites, since the reactivity of monomer is sterically
Chung Tze-Chiang
Dong Jinyong
Monahan Thomas J.
Teskin Fred
The Penn State Research Foundation
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