Stable Star-Structured Functional Polyolefins (ExxonMobil)

Stable Star-Structured Functional Polyolefins (ExxonMobil)
United States Patent Application 20160159944
Yang; Yong ;   et al.   June 9, 2016
Applicant: ExxonMobil Chemical Patents Inc.
Abstract
Stable star-structured functional polyolefins and methods of making them, the functional polyolefins comprising a polyolefin bound at any position along its chain length to at least one nucleophile-containing silane of the following formula: ##STR00001## wherein Y is a di- or trivalent linker group selected from heteroatoms, C1 to C10 alkylenes, and other groups disclosed herein; Nu is a nucleophilic atom or unsaturation group; R5 is selected from hydrogen, and C1 to C10 alkyls, and other groups as disclosed herein; X is a divalent group selected from linear and branched alkylenes and heteroatom-alkylenes, and other groups as disclosed herein; and PO is a polyolefin having a weight average molecular weight of at least 400 g/mole; with the proviso that at least one of R1, R2, and R3 is selected from the same or different functional polyolefin moieties. Star-structured functional polyolefins are useful as filler dispersive additives in tire formulations and processing aids.
FIELD OF THE INVENTION
[0002] The present invention relates to branched functional polyolefins and to methods of obtaining such polyolefins.
BACKGROUND OF THE INVENTION
[0003] Functional polyolefins with high reactivity and high stability for various multi-component formulations such as composites, adhesives, and tires are always challenging. Functional polyolefins with complex architectures are critical in performance enhancement and rheological properties for some applications, which adds another layer of difficulty in efficient and economic synthesis/process. Such functional polymers have a particularly desirable use in dispersing agents for inorganic particles within polymer matrices, and as processing agents for difficult to process polymers.
[0004] It is desirable to add fillers to polymer compositions to improve properties such as heat distortion temperatures, dimensional stability, and stiffness. However, this presents some problems. First, many fillers are not compatible with polymers, especially polyolefin polymers which tend to be highly non-polar. A further problem is that there is an increasing desire to use nanoparticles (less than 0.1 .mu.m in one dimension) to improve the performance of thin films and micro and nano-fibers made from polyolefins. Such nanoparticles have very high surface areas so they disperse even more poorly than larger particles.
[0005] Dispersing polar nanofillers in non-polar polyolefins has always been challenging. Despite the theoretical promises of having a polyolefin nanocomposite with nano-dispersed silica clusters for enhancements in mechanical stiffness, strength, rheological melt strength, shear thinning, and in thermal heat distortion resistance, there are currently no polyolefin-silica nanocomposites commercially available. Prior disclosures have demonstrated that polyolefins can form structures with aminosilanes for improved silica dispersion in polymer blends, and for forming hydrophilic compositions for such applications as corrosion resistant coatings. What is needed is a way to thoroughly disperse polar nanoparticles such as silica into a polyolefin (e.g., polyethylene and/or polypropylene) matrix. In particular, what is needed is a method to effect or "control" condensation by aminosilane species to form complex hydrophilic-hydrophobic materials. The present invention(s) is directed to such an end.
[0006] Related disclosures include U.S. Pat. No. 8,840,996; U.S. Pat. No. 8,669,326; U.S. Pat. No. 8,816,027; U.S. Pat. No. 8,623,974; US 2014/088264; US 2014/275433; U.S. Pat. No. 8,372,930; US 2013/0197180; U.S. Pat. No. 8,835,563; U.S. Pat. No. 8,501,894; US 2011/0178233; US 2013/0296471; WO 2004/024800; WO 2013/041151; WO 2015/023382; WO 2009/155517; WO 2009/155510; WO 2009/155471; WO 2009/155472; WO 2014/052200; WO 2012/134717; Gelest Inc., "Silane Coupling Agents: Connecting Across Boundaries" (2006); and S. B. Herzon et al., "Hydroaminoalkylation of Unactivated Olefins with Dialkylamines," in 130, J. AM. CHEM. SOC., pp. 14940-14941 (2008).
SUMMARY OF THE INVENTION
[0007] Disclosed are stable star-structured functional polyolefins comprising a polyolefin bound at any position along its chain length to at least one nucleophile-containing silane of the following formula:
##STR00002##
wherein: [0008] "Y" is a di- or trivalent linker group selected from heteroatoms, C.sub.1 to C.sub.10 alkylenes, heteroatom substituted C.sub.1 to C.sub.10 alkylenes, C.sub.6 to C.sub.20 arylenes, and heteroatom substituted C.sub.6 to C.sub.20 arylenes; R.sup.4 is selected from hydrogen, heteroatoms, and C.sub.1 to C.sub.10 alkyls; [0009] "Nu" is a nucleophilic atom or unsaturation group; preferably nitrogen, oxygen, sulfur, or phosphorous; [0010] R.sup.5 is selected from hydrogen, and C.sub.1 to C.sub.10 alkyls, C.sub.1 to C.sub.10 aminoalkyls, C.sub.6 to C.sub.20 aryls, C.sub.7 to C.sub.22 alkylaryls, and C.sub.7 to C.sub.22 arylalkyls; [0011] "X" is at least a divalent group selected from heteroatoms, C.sub.1 to C.sub.20 linear alkylenes, a C.sub.2 to C.sub.22 aminoalkylenes, C.sub.2 to C.sub.22 divalent ethers, and C.sub.2 to C.sub.22 or C.sub.40 branched alkylene; [0012] at least one silane group wherein each R.sup.1, R.sup.2, and R.sup.3 are independently selected from hydrogen, hydroxide, C.sub.1 to C.sub.10 alkoxys, C.sub.6 to C.sub.30 aryloxys, C.sub.7 to C.sub.30 arylalkyloxys, and C.sub.1 to C.sub.10 alkylamines, wherein any 2- or more groups can form an aliphatic or aromatic cyclic structure that includes the silicon atom; and [0013] "PO" is a polyolefin having a weight average molecular weight ("Mw") of at least 400 g/mole; and "n" is an integer within the range from 1, or 2, or 5 to 10, or 20, or 30; [0014] with the proviso that at least one of R.sup.1, R.sup.2, and R.sup.3 is selected from "functional polyolefin moieties" having the following structure:
[0014] ##STR00003## [0015] wherein, the functional polyolefin moiety is covalently bonded through any one or more of R.sup.1', R.sup.2', or R.sup.3'; and where any other one or more of R.sup.1', R.sup.2', or R.sup.3' is independently selected from hydroxide, C.sub.1 to C.sub.10 alkoxys, C.sub.6 to C.sub.30 aryloxys, C.sub.7 to C.sub.30 arylalkyloxys, and C.sub.1 to C.sub.10 alkylamines, wherein any 2- or more groups can form an aliphatic or aromatic cyclic structure that includes the silicon atom functional polyolefin moieties.
[0016] Also disclosed is a method of forming stable star-structured functional polyolefins comprising combining at least one polyolefin with at least one nucleophile-reactive group or unsaturation at one or both of the chain ends and/or inside the chain; and at least one nucleophile-containing silane; preferably an aminosilane to form a functional polyolefin; wherein the at least one site of unsaturation or nucleophile-reactive group forms a covalent bond with the nucleophilic atom of the nucleophile-containing silane, and effecting condensation between functional polyolefins to form star-structured functional polyolefins having a branching number of at least 2.
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