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Maleated polypropylenes and processes for the preparation thereofRelated Patent Categories: Synthetic Resins Or Natural Rubbers -- Part Of The Class 520 Series, Natural Rubber Compositions Having Nonreactive Materials (dnrm) Other Than: Carbon, Silicon Dioxide, Glass Titanium Dioxide, Water, Hydrocarbon, Halohydrocarbon, Ethylenically Unsaturated Reactant Admixed With A Preformed Reaction Product Derived From: (a) At Least One Polycarboxylic Acid, Ester, Or Anhydride; (b) At Least One Polyhydroxy Compound; And (c) At Least One Fatty Acid Glycerol Ester, Or A Fatty Acid Or Salt Derived From A Naturally Occurring Glyceride, Tall Oil, Or A Tall Oil Fatty Acid, At Least One Solid Polymer Derived From Ethylenic Reactants Only, Polymer Derived From Ethylenic Reactants Only Mixed With Ethylenic Reactant, Ethylenic Reactant Contains A Chalcogen Heterocycle, Cyclic AnhydrideMaleated polypropylenes and processes for the preparation thereof description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070287805, Maleated polypropylenes and processes for the preparation thereof. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation of, and claims priority to, U.S. application Ser. No. 10/140,429, filed May 6, 2002, which is currently pending and which, in turn, is related to and claims the priority benefit of U.S. Provisional Patent Application No. 60/289,269, filed May 6, 2001. Each of these applications is assigned to the assignee of the present invention and is incorporated herein by reference. FIELD OF INVENTION [0002] The present invention relates to functionalized polyolefin wax, to maleated polypropylenes, and to methods for producing such waxes and maleated polypropylenes. More specifically, the invention relates to methods for producing maleated polypropylenes having a relatively high percentage of bound maleic anhydride moieties, to the maleated polypropylenes obtained from such methods, and to emulsible polyolefin wax from which high clarity emulsions can be prepared. BACKGROUND [0003] Polyolefin waxes, including maleated polyolefins, and in particular maleated polypropylenes, are known in the art and find use in a wide range of applications. For example, emulsible polyolefin waxes are well known and are commonly used in glossy, protective substrates such as floor polish and the like. Maleated polypropylenes are useful for compatibilizing polymers, particularly polyolefins with various polar substrates, including polar polymers, mineral fillers, and the like. Such copolymers are also known for use in metal bonding adhesive compositions. [0004] Unfortunately, many products made with conventional polyolefin wax, including emulsions of conventional polyolefin waxes, tend to be low in clarity and high in color. This is due, in part, to the general lack of colorless polyolefin wax. The problem is compounded by the process of functionalizing, such as the maleation of polypropylene, which tends to color and reduce clarity of the polyolefin wax. [0005] Many classes of techniques are known for grafting maleic anhydride to a polymer backbone. For example, solid state maleation is carried out below the melting point of the polymer and the reaction takes place on the exposed surface of the polymer. In solvent based grafting, the substrate polymer is dissolved in an appropriate solvent and the grafting reaction takes place in solution. In melt grafting, maleic anhydride is grafted onto a polypropylene backbone by introducing maleic anhydride, or a precursor thereof, into a melt of polypropylene polymer, typically in the presence of a catalyst. [0006] Applicants have found that the conditions which have heretofore typically been used for grafting maleic anhydride onto a polymer backbone, and particularly the conditions which typically occur in melt grafting, tend to result in an undesirably small percentage of the maleic anhydride being bound to the polymer backbone. More particularly, applicants have discovered that prior art methods, as disclosed for example in U.S. Pat. No. 3,642,722--Knowles et al and U.S. Pat. No. 4,506,056--Gaylord, each of which is incorporated herein by reference, result in maleated polypropylene products wherein less than about 50% of the maleic anhydride in the product of the grafting reaction is bound to the polypropylene backbone. Applicants believe that the remainder of the maleic anhydride present in the prior art grafting reaction product is unreacted and/or oligomeric maleic anhydride, as indicated by the article/work of Scott M. Hacker, one of the co-inventors hereof, entitled "Not All Maleated Polyolefins Are Created Equal" which is attached as an addendum hereto. [0007] Applicants have recognized not only the above-noted drawbacks of the prior art, but that these drawbacks result in a product with poor performance properties in certain applications. More particularly, applicants have noted that one important use for maleated polypropylene is as a compatibilizing agent, particularly for polar substrates, fibers and filler. Applicants appreciate that as the level of bound maleic anhydride increases, the compatibilizing properties of the product increase. While bound maleic anhydride contributes to the desirable properties of maleated polypropylenes, unreacted and oligomeric maleic anhydrides present in the product tend to inhibit such properties. In fact, unbound maleic anhydride compounds remaining in maleated polypropylene products tend to act as scavengers and inhibit the compatibilization properties of the maleated polypropylene. BRIEF DESCRIPTION OF DRAWINGS [0008] FIG. 1 shows a plot of clarity/Klett number of an emulsion made from the emulsible polyolefin of the present invention mixed with a non-emulsible polypropylene as a function of the polypropylene's molecular weight. [0009] FIG. 2 shows a plot of SAP versus bound maleic anhydride for high and low molecular weight polypropylene. SUMMARY OF THE INVENTION [0010] The present invention is directed to methods for advantageously producing maleated polypropylenes having a relatively high percentage of bound maleic anhydride, based on the total amount of maleic anhydride moieties present in the grafting reaction product, and the maleated polypropylenes produced therefrom. The methods of the present invention overcome the disadvantages of the prior art by facilitating the production of maleated polypropylenes wherein at least about 60%, and preferably at least about 75% of the maleic anhydride moieties in the grafting reaction product are bound to the polypropylene. Unless otherwise indicated herein, all percentages are intended to refer to weight percent. [0011] The improved process is characterized judiciously selecting the type and nature of the reactants used and adding maleic anhydride to the selected polypropylene, and preferably polypropylene melt, under time, temperature and pressure conditions effective to graft at least about 55%, and even more preferably at least about 60%, of maleic anhydride to the polymer backbone, said percentage being based on the total maleic anhydride moieties, including precursors thereto, present in the grafting reaction product. [0012] As used herein, the term "grafting reaction product" refers to maleated polypropylene, together with any unreacted components, by products and impurities, after the grafting reaction is deemed to be substantially completed, but before any subsequent purification steps. As used herein, the term "polypropylene" refers to and includes homopolymers of polypropylene and all forms of polypropylene copolymers, and in particular polypropylene-polyethylene copolymers, provided that at least about the majority of the polymer is formed of polypropylene moieties on a mole percent basis. As used herein, the term copolymer refers to and includes terpolymers and the like. Preferably, the polyolefin reactant of the present invention is polypropylene homopolymer, or a copolymer of propylene and ethylene wherein the concentration by weight of ethylene is less than about 10%, and more preferably less than about 5%. As used herein, the term "maleated polypropylene" refers generally to the reaction product formed by grafting maleic anhydride, preferably by covalent bonding, to the polymer backbone of polypropylene. As is known in the art, therefore, such grafting reaction products in commercial applications generally comprise not only maleated polypropylene but also as unbound maleic anhydride and oligomeric maleic anhydride. The term "bound maleic anhydride" as used herein, refers generally to the moieties derived from maleic anhydride which are grafted to the polypropylene backbone according to the present invention. "Unbound maleic anhydride" refers generally to unreacted maleic anhydride or oligomeric anhydride present in the grafting reaction product. In embodiments in which the reaction takes place in the melt, the grafting reaction product is generally the melt at the conclusion of the grafting reaction step. [0013] In certain preferred embodiments, the maleic anhydride is introduced to the polypropylene, and preferably a polypropylene melt, at a rate that maintains the concentration of maleic anhydride in the reaction mixture (e.g., in the melt) at no greater than about 120%, and even more preferably no greater than 100%, of the solubility limit of the maleic anhydride in the polypropylene at the reaction conditions. [0014] Applicants have unexpectedly and counter intuitively discovered that grafting maleic anhydride to polypropylene in a reaction mixture wherein the amount of unreacted maleic anhydride in the mixture is maintained at a relatively low level is capable of producing a reaction product copolymer that either contains a very high level of bound maleic anhydride and/or contains a relatively low level of oligomeric maleic anhydride. In certain preferred embodiments, the polyolefin wax, for example maleated polypropylene of the present invention, has a Gardner color index of no greater than about 9, more preferably no greater than about 8, and even more preferably no greater than about 7. [0015] For embodiments in which the reactant comprises polypropylene-polyethylene copolymer, applicants have also unexpectedly discovered that the amount of maleic anhydride which is bound in the grafting reaction is generally related to the amount of polyethylene in the copolymer. More particularly, it is generally preferred that the copolymer comprise up to about 10 mole % polyethylene, more preferably up to about 5 mole % of polyethylene, and even more preferably from about 0.5 mole % to about 3 mole % polyethylene. Applicants have discovered that polyethylene levels as described herein help to produce the claimed high levels of bound maleic anhydride without negatively effecting the compatibalization properties of the reaction product. [0016] The present invention, therefore, provides an improved graft maleic anhydride/polypropylene copolymer product comprising polypropylene backbone, bound maleic anhydride and from about 0% to about 40% of unbound maleic anhydride wherein at least about 60 wt % of said maleic anhydride moieties, more preferably at least about 65 wt % of said maleic anhydride moieties, and even more preferably at least about 70% of said moieties are bound maleic anhydride, based on the total maleic anhydride moieties in the reaction product. In especially preferred embodiments, at least about 75% of said moieties are bound maleic anhydride, based on the total maleic anhydride moieties in the reaction product. Description of Preferred Embodiments [0017] One aspect of the present invention is directed to methods for producing maleated polypropylenes comprising reacting maleic anhydride, or a precursor thereof, with polypropylene in a reaction mixture. It is contemplated that various particular process and unit parameters can be adapted for use with the present reaction step, and a wide range of known methods and steps for combining and reacting maleic anhydride and polypropylene in a reaction mixture can be used according to the present invention. For example, it is contemplated that processes of the present invention may comprise one or more of the classes of reaction procedures known in the art, including: melt grafting, solid state grafting, solution grafting, and the like. However, the present invention is preferably conducted by melt grafting. [0018] The steps of the present invention may be conducted on a continuous basis, on a batch basis, or on a combination of both. Those of skill in the art will, in view of the teachings contained herein, be able to adopt the present invention to any of these modes of operation without undue experimentation. Continue reading about Maleated polypropylenes and processes for the preparation thereof... Full patent description for Maleated polypropylenes and processes for the preparation thereof Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Maleated polypropylenes and processes for the preparation thereof patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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