Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2001-12-21
2004-03-16
Sergent, Rabon (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C521S106000, C521S108000, C521S123000, C521S124000, C521S137000, C521S174000, C521S176000, C524S139000, C524S711000, C528S055000, C528S076000, C528S905000
Reexamination Certificate
active
06706844
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to polyurethane products produced using polyether polyols made in the presence of aluminum phosphonate catalysts and, more particularly, to use of polyetherols having very low unsaturation to make polyurethane foams, coatings, adhesives, sealants, elastomers and other products.
Polyoxyalkylene polyether polyols are well known compounds utilized in the formation of a variety of polyurethane products, such as foams, coatings, adhesives, sealants and elastomers. As a general matter, these polyols are produced by polyoxyalkylation of an initiator molecule with ethylene oxide, propylene oxide, butylene oxides, or mixtures thereof. The initiator molecules contain alkylene oxide-reactive hydrogens like hydroxyls and amines. This oxyalkylation is generally conducted in the presence of a catalyst. The most common catalysts are basic metal catalysts such as sodium hydroxide, potassium hydroxide, or alkali metal alkoxides. One advantage of these base catalysts is that they are inexpensive and readily available. Use of these base catalysts, however, is associated with a range of problems. One of the major problems is that the 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 urethane product. Thus, as the oxyalkylation reaction is continued more of this product, generally measured as the unsaturation content of the polyol, is formed. This leads to reduced functionality of the polyol and a broadening of the molecular weight distribution of the final polyol mixture. The amount of unsaturation content may approach 30 to 40% with unsaturation levels of 0.08 meq/g KOH or higher.
In an attempt to reduce the unsaturation content of polyols a number of other catalysts 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 of them are toxic. Like potassium hydroxide catalysts, these higher molecular weight hydroxide catalysts are known to affect the polyurethane forming reaction, they are generally removed prior to work-up of any polyol for use in polyurethane systems.
A second line of alternative catalyst development has been formation of double metal cyanide (DMC) catalysts. These catalysts are typically based on zinc hexacyanocobaltate. With the use of DMC catalysts it is possible to achieve unsaturations in the range of 0.003 to 0.010 meq/g KOH. 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 base catalysts. The process of making polyols using DMC is also different from based catalyzed reactions. During use of DMC catalysts there is an initial significant, and often unpredictable, lag time before the catalyst begins catalyzing the reaction. Another difficulty is that ethylene oxide does not add uniformly to growing polymer chains utilizing DMC catalysts. Chain transfer is slow relative to chain growth, so all the ethylene oxide adds to only a few of the polymer chains, leaving the rest unreacted. The result is a polyol of such low quality that it has no commercial value. To add ethylene oxide to a growing chain the DMC catalysts must be replaced with the typical base catalysts, thus adding steps. In addition, it is generally believed that the DMC catalysts should be removed prior to work-up of any polyol for use in polyurethane systems. Finally, polyols generated using DMC catalysts are not mere “drop in” replacements for similar size and functionality polyols produced using the typical base catalysts. Indeed, it has been found that often DMC catalyzed polyols have properties very different from equivalent polyols produced using, for example, potassium hydroxide. It is recognized in the art that polyols made utilizing DMC catalysts contain small amounts of high molecular weight compounds, which can affect utilization of these polyols in polyurethane systems, particularly foaming. The so-called high molecular weight tail has been identified in amounts of greater than 100 ppm and variously described as polymer of molecular weight greater than 50,000 Daltons, see U.S. Pat. No. 5,919,988 which is incorporated herein by reference. The presence of the so-called high molecular weight tail in amounts of greater than 300 has been identified as a cause of foam destabilization and collapse.
Thus, there exists a need for a class of catalysts that can be used for the oxyalkylation of initiator molecules by alkylene oxides that is inexpensive, capable of producing very low unsaturation polyols, does not require removal from the polyol prior to utilization in polyurethane systems, and that produces a polyol having properties that are the same or better than those in a polyol produced using base catalysts. Preferably the new class of catalysts can be used in existing systems and equipment using standard manufacturing conditions.
SUMMARY OF THE INVENTION
In general terms, the present invention provides low unsaturation polyetherols produced using an aluminum phosphonate catalyst and provides for their use in polyurethane applications.
One embodiment the present invention is a polyurethane foam produced according to a process comprising the steps of: providing at least one alkylene oxide; providing at least one initiator molecule having at least one alkylene oxide reactive hydrogen; reacting the at least one alkylene oxide with the at least one initiator molecule in the presence of an aluminum phosphonate catalyst to form a polyether polyol; and reacting the polyether polyol formed in step c) with at least one polyisocyanate in the presence of a blowing agent to form a polyurethane foam.
Another embodiment of the invention is a composition of matter comprising a polyurethane material, preferably selected from the group consisting of flexible foams, rigid foams, coatings, adhesives, sealants, elastomers and thermoplastics, and aluminum phosphonate catalyst having the general structure of RPO-(OAlR′R″)2 or residues of said aluminum phosphonate catalyst, wherein P represents pentavalent phosphorous; O represents oxygen; Al represents aluminum; R comprises a hydrogen, an alkyl group, or an aryl group; and R′ and R″ independently comprise a halide, an alkyl group, an alkoxy group, an aryl group, or an aryloxy group, and/or residues of said aluminum phosphonate. In a further embodiment, said aluminum phosphonate is present at levels of from approximately 0.001 to 5.0 weight percent based on the total weight of the polyurethane. Residues of said aluminum phosphonate catalyst are considered to be aluminum phosphonates salts, often crosslinked through aluminum-oxygen bonds.
In a further embodiment, R is a methyl group; and R′ and R″ independently comprise one of an ethyl group, an ethoxy group, a propyl group, a propoxy group, a butyl group, a butoxy group, a phenyl group, or a phenoxy group.
It is another object of the invention to provide a polyurethane product comprising greater than 0.001 weight percent of aluminum phosphonate catalyst and/or aluminum phosphonate catalyst residues based on the total weight of the polyurethane product, said aluminum phosphonate catalyst having the general structure of RPO-(OAlR′R″)2 wherein: O represents oxygen; P represents pentavalent phosphorous; Al represents aluminum; R comprises a hydrogen, an alkyl group, or an aryl group; and R′ and R″ independently comprise a halide, an
BASF Corporation
Borrego Fernando A.
Sergent Rabon
LandOfFree
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