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  Carboxy-modified aluminum-based catalyst compositionsRelated Patent Categories: Catalyst, Solid Sorbent, Or Support Therefor: Product Or Process Of Making, Catalyst Or Precursor Therefor, Organic Compound ContainingThe Patent Description & Claims data below is from USPTO Patent Application 20070117712. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This application is a continuation-in-part of and claims the benefit of co-pending U.S. patent application Ser. No. 10/036,679, filed on Dec. 21, 2001. TECHNICAL FIELD [0002] The present invention generally relates to a catalyst composition. More specifically, the present invention relates to a carboxy-modified aluminum-based catalyst composition, such as a carboxy-modified aluminum phosphate or a carboxy-modified aluminum phosphonate, that is typically used to form a polyether polyol. BACKGROUND OF THE INVENTION [0003] Various catalyst compositions for use in forming polyoxyalkylene polyether polyols, i.e., polyether polyols, are known in the art. Polyether polyols, which are well known compounds, are utilized, in conjunction with a cross-linking agent, such as an organic isocyanate, to form or produce a variety of polyurethane products, foamed and non-foamed, i.e., elastomeric, such as polyurethane foams and polyurethane elastomers. As a general matter, these polyols are produced by polyoxyalkylation of an initiator molecule with an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxides, or mixtures thereof. The initiator molecules contain alkylene oxide-reactive hydrogens like those found in hydroxyl groups and amine groups. This oxyalkylation is generally conducted in the presence of a catalyst composition. [0004] The most common catalyst compositions are basic metal catalysts such as sodium hydroxide, potassium hydroxide, or alkali metal alkoxides. One advantage of these basic metal catalysts is that they are inexpensive and readily available. Use of these basic metal catalysts, however, is associated with a range of problems. One of the major problems is that oxyalkylation with propylene oxide has associated with it a competing rearrangement of the propylene oxide into allyl alcohol, which continually introduces a monohydroxyl-functional molecule. This monohydroxyl-functional molecule is also capable of being oxyalkylated. In addition, it can act as a chain terminator during the reaction with isocyanates to produce the final polyurethane product. Thus, as the oxyalkylation reaction is continued more of this unwanted product, generally measured as the unsaturation content of the polyol, is formed. This leads to reduced functionality and a broadening of the molecular weight distribution of the polyol. The amount of unsaturation content may approach 30 to 40 molar % with unsaturation levels of 0.090 meq KOH/g or higher. [0005] In an attempt to reduce the unsaturation content of polyether polyols, a number of other catalyst compositions have been developed. One such group of catalysts includes the hydroxides formed from rubidium, cesium, barium, and strontium. These catalysts also present a number of problems. The catalysts only slightly reduce the degree of unsaturation, are much more expensive, and some are toxic. [0006] A further line of catalyst development for polyether polyol production focuses on double metal cyanide (DMC) catalysts. These catalysts are typically based on zinc hexacyanocobaltate. With the use of DMC catalysts, it is possible to achieve relatively low unsaturation content in the range of 0.003 to 0.010 meq KOH/g. While the DMC catalysts would seem to be highly beneficial they also are associated with a number of difficulties. As a first difficulty, there is a relatively high capital cost involved in scaling up of and utilization of DMC catalysts. The catalysts themselves have an extremely high cost compared to the basic metal catalysts. Further, when forming a polyether polyol using a DMC catalyst, there is a significant initial lag time before the DMC catalyst begins to catalyze the reaction. It is not possible to add ethylene oxide onto growing polyol chains utilizing DMC catalysts. To add ethylene oxide to a growing chain, the DMC catalysts must be replaced with the typical basic metal catalysts, thus adding complexity and steps. In addition, it is generally believed that the DMC catalysts should be removed prior to work-up of any polyether polyol for use in forming polyurethane products. Finally, polyether polyols generated using DMC catalysts are not mere "drop in" replacements for similar size and functionality polyols produced using the typical basic metal catalysts. Indeed, it has been found that often DMC catalyzed polyether polyols have properties very different from equivalent polyether polyols produced using, for example, potassium hydroxide. [0007] More recent lines of catalyst development for polyether polyol production focus on aluminum phosphate and aluminum phosphonate catalysts. However, these catalysts also have drawbacks. Both aluminum phosphate catalysts and aluminum phosphonate catalysts may be subject to slow hydrolysis upon exposure to water, such as the water present in the air as humidity or even water present as an impurity in the initiator molecule and alkylene oxide reactants. [0008] Finally, it is known that simple carboxy-modified aluminum compounds, i.e., those not including phosphate and/or phosphonate, are not catalytically active and are, therefore, not useful for the formation of polyether polyols. [0009] Thus, there exists a need for catalyst compositions that can be used for the oxyalkylation of initiator molecules by alkylene oxides that are inexpensive, capable of producing very low unsaturation polyether polyols, do not require removal from the polyether polyol prior to utilization to form a polyurethane product, and that produce a polyether polyol having properties that are the same or better than those in polyether polyols produced using basic metal catalysts. The need also extends to catalyst compositions that have improved stability as determined by resistance to hydrolysis upon exposure to water. It would also be beneficial if the new class of catalyst compositions could be used in existing systems and equipment using standard manufacturing conditions. SUMMARY OF THE INVENTION AND ADVANTAGES [0010] A carboxy-modified aluminum-based catalyst composition according to the present invention is of the general formula P(O)(OAlR'R'').sub.3 or RP(O)(OAlR'R'').sub.2. In this formula, O represents oxygen, P represents pentavalent phosphorous, Al represents aluminum, R comprises hydrogen, an alkyl group, or an aryl group, and R' and R'' independently comprise a halide, an alkyl group, a haloalkyl group, an alkoxy group, an aryl group, an aryloxy group, or a carboxy group, so long as at least one of R' and R'' is a carboxy group. [0011] Importantly, the carboxy-modified aluminum based catalyst composition utilized in the present invention remains soluble in polyether polyols and has catalytic activity comparable to, if not exceeding that of, the basic metal and DMC catalysts. When the carboxy-modified aluminum-based catalyst composition is used in the oxyalkylation of initiator molecules by alkylene oxides, very low unsaturation (e.g. less than 0.080 meq KOH/g such as less than or equal to 0.020 meq KOH/g) polyether polyols are formed. Also, the catalyst composition used herein is inexpensive as compared to the DMC catalyst of the prior art. Furthermore, there is no need to remove, by neutralization and filtration, the catalyst composition or any of its residue from the polyether polyol prior to use of the polyether polyol in forming polyurethane products. Physical properties of polyether polyols that are produced with this catalyst composition are not negatively impacted, and the catalyst composition can be used in existing systems and equipment using standard manufacturing conditions. [0012] The carboxy modification of this aluminum-based catalyst composition imparts stability on the catalyst composition. That is, this catalyst composition is stable in the sense that it is not moisture sensitive. As such, this catalyst composition does not hydrolyze upon exposure to water. Furthermore, the improved stability of the carboxy-modified aluminum-based catalyst composition of the present invention, as compared to the stability of the alkyl and alkoxy derivatives typically associated with more conventional aluminum-based catalysts, such as aluminum phosphate and aluminum phosphonate catalysts, provides for a greater freedom in manufacturing processes. For example, with the catalyst composition of the present invention, there is less concern for the amount of water present as humidity or as an impurity in the reactants. Finally, unlike the simple carboxy-modified aluminum compounds described above, the carboxy-modified aluminum-based catalyst compositions used in the present invention are catalytically active in the formation of polyether polyols. DETAILED DESCRIPTION [0013] A carboxy-modified aluminum-based catalyst composition is disclosed. The catalyst is used, as described in more detail below, in the formation of a polyether polyol. The polyether polyol, i.e., polyetherol, itself and a method of forming the polyether polyol are also disclosed herein. Generally, the method uses the catalyst composition to form the polyether polyol. It is to be understood that the terminology "carboxy" as used herein is interchangeable with the terminology "carboxylate". As such, the catalyst of the present invention is also appropriately referred to as a carboxylate-modified aluminum-based catalyst. For convenience in description, the carboxy-modified aluminum based catalyst composition is also referred to and described below simply as the catalyst composition or the catalyst. [0014] Use of this catalyst enables production of polyether polyols having very low unsaturation as compared to a similarly sized polyether polyols produced using typical basic metal catalysts. In addition, other than the very low degree of unsaturation, polyether polyols formed via catalysis with the catalyst have properties that are the same or better than those produced using the typical basic metal catalysts. The catalyst can be synthesized in a very straightforward manner and is inexpensive compared to many of the other catalysts capable of producing these very low unsaturation polyether polyols. The carboxy-modified aluminum-based catalyst composition is stable in that it is not sensitive to moisture and therefore provides the advantage of freedom in manufacturing as described above. We have also found that the catalyst does not have to be removed after formation of the polyether polyol prior to its use in forming, i.e., producing, a polyurethane product. The polyurethane product can be foamed or non-foamed, i.e., elastomeric, and is described additionally below. The catalyst can be readily substituted in existing oxyalkylation procedures that utilize basic metal catalysts, such as potassium hydroxide, with virtually no modifications to the procedure. Unlike the DMC class of catalysts, the catalyst used in the present invention exhibit no lag time and are capable of polyoxyalkylation utilizing ethylene oxide. [0015] The method of forming the polyether polyol includes the step of providing at least one alkylene oxide. Suitable alkylene oxides include, but are not limited to, ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin or mixtures of these alkylene oxides. As is known, alkylene oxides are used to polyoxyalkylate an initiator molecule, described additionally below, to form polyether polyols. [0016] The method of forming the polyether polyol also includes the step of providing at least one initiator molecule. As understood by those skilled in the art, the initiator molecule has at least one alkylene oxide reactive hydrogen. More preferred alkylene oxides have at least two alkylene oxide reactive hydrogens. Suitable initiator molecules include, but are not limited to, an alcohol, a polyhydroxyl compound, a mixed hydroxyl and amine compound, an amine, a polyamine compound, or mixtures of these initiator molecules. Examples of alcohols include, but are not limited to, aliphatic and aromatic alcohols, such as lauryl alcohol, nonylphenol, octylphenol and C.sub.12 to C.sub.18 fatty alcohols. Examples of the polyhydroxyl compounds include, but are not limited to, diols, triols, and higher functional alcohols such as sucrose and sorbitol. Examples of amines include, but are not limited to, aniline, dibutylamine, and C.sub.12 to C.sub.18 fatty amines. Examples of polyamine compounds include, but are not limited to, diamines such as ethylene diamine, toluene diamine, and other polyamines. [0017] In a preferred embodiment, a pre-reaction initiator molecule is pre-reacted with at least one alkylene oxide to form an oligomer. Typically, such an oligomer has a number average molecular weight of from 200 to 1,500 Daltons. The oligomer is then used as the initiator molecule and reacted with the alkylene oxide in the presence of the catalyst to form the polyether polyol as described below. Suitable pre-reaction initiator molecules include those described above in the context of the initiator molecule. [0018] The at least one alkylene oxide is reacted with the at least one initiator molecule in the presence of the catalyst or residue thereof to form the polyether polyol. Without intending to be bound by theory, the catalyst may undergo exchange reactions to some extent with the initiator molecule(s) in a reversible manner to form a modified carboxy-modified aluminum-based compound, which is also catalytically active. This modified aluminum-based compound is also referred to as a residue. Preferably, the initiator molecule and the alkylene oxide or oxides are reacted in the presence of the catalyst for a period of time from 15 minutes to 15 hours. Typically, this period of time is sufficient to form polyether polyols having an equivalent weight of from 100 to 10,000, more preferably from 200 to 2,000, and most preferably from 500 to 2,000, Daltons. The reaction between the initiator molecule and the alkylene oxide is generally conducted at a temperature of from 95.degree. C. to 150.degree. C., and more preferably at a temperature of from 105.degree. C. to 130.degree. C. [0019] Generally, the catalyst is utilized in an amount of from 0.1 to 5.0 weight percent based on the total weight of the polyether polyol, more preferably at levels of from 0.1 to 0.5 weight percent on the same basis. The catalyst composition of the present invention is of the general formula P(O)(OAlR'R'').sub.3 or RP(O)(OAlR'R'').sub.2. Continue reading... Full patent description for Carboxy-modified aluminum-based catalyst compositions Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Carboxy-modified aluminum-based catalyst compositions patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. 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