Patent Description:
Polyether polyols are often manufactured using a catalyzed reaction of initiators having active hydrogen atoms with epoxides such as, for example, ethylene oxide and/or propylene oxide. Alkalinity is introduced into the polyether polyols, for example, by using alkaline metal hydroxides as catalysts.

Potassium hydroxide (KOH) and sodium hydroxide (NaOH) are some examples of typical alkaline catalysts used. In general, the metal hydroxide catalyst is added to the starter (usually a hydroxyl group containing compound), and equilibrium between the metal hydroxide and the starter occurs. This equilibrium is as shown in the following equation (using KOH as the alkaline catalyst):.

Both the hydroxide and the alkoxide can react with epoxides. This is often acceptable for short chain (low molecular weight) polyols, but the reaction of water is undesirable in the preparation of long chain (high molecular weight) polyols. It is, therefore, necessary to force the above equilibrium to the right by removing the water to convert hydroxide to alkoxide. The total amount of alkalinity remains constant and equals the amount of KOH originally added.

Once polymerization of the epoxide(s) is completed, the resulting crude polyether polyol contains alkaline ions from the catalyst that must be removed until a very low level of such alkaline ions remains. Several processes for such removal are known.

One method of removing alkaline ions from a crude polyether polyol is by treatment with an acidic cation exchange resin. (<CIT>, <CIT>, <CIT>, <CIT>) In this process, the crude polyether polyol is passed through a porous bed comprising the cation exchange resin, sometimes a copolymer of styrene and divinylbenzene with sulfonic acid groups, whereby an ion exchange occurs between the alkaline ions in the crude polyether polyol and the cation exchange sites on the resin, thereby purifying the polyether polyol. In some industrial processes the crude polyether polyol is also passed through a "mixed" ion exchange bed that includes a strong cation exchange resin that includes sulfonic acid groups and a strong anion exchange resin that includes quaternary ammonium and/or tertiary amine groups. The use of such a "mixed" bed downstream of a cation exchange resin bed can be beneficial for removing any alkali metal ions that "pass through" the upstream cation exchange resin bed and to neutralize acid that may be present in order to produce a polyether polyol having a very low acid value.

Such ion exchange purification processes are, however, not without their disadvantages. Notably, polyether polyol and polyurethane foam producers are under increased pressure to reduce the presence of odor bodies. One such odor body that sometimes gives rise to complaints is <NUM>-Methyl-<NUM>-Pentenal ("2M2P"), C<NUM>H<NUM>O, which can form by acid catalyzed reaction of allyl alcohol to propionaldehyde, which then condenses to 2M2P and water. Purification of long chain, low hydroxyl number polyether polyols via ion exchange, however, has led to formation of 2M2P. These polyols are often used in producing flexible polyurethane foams that are often used in consumer applications, such as foam mattresses and vehicle seating, where the presence of odor bodies is particularly undesirable.

As a result, it would be desirable to provide a method of purifying polyether polyols, such as low (such as less than <NUM> KOH/g) hydroxyl number polyether polyols via an ion exchange process, to produce purified polyether polyols that have low (such as <NUM> ppm or less) 2M2P content, low (such as no more than <NUM> KOH/g) acid number, and low (such as no more than <NUM> meq/kg) residual alkalinity from an alkaline catalyst.

In some respects, the invention is directed to processes for removing alkali metal ions from a polyether polyol. These processes comprise: (a) passing a mixture comprising the polyether polyol and the alkali metal ions through a first bed comprising a cation exchange resin comprising carboxylic acid and/or phosphonic acid groups to remove alkali metal ions from the mixture; and (b) passing the product of step (a) through a second bed comprising an anion exchange resin comprising quaternary ammonium groups and a cation exchange resin comprising carboxylic acid and/or phosphonic acid groups, wherein the first bed and the second bed are each substantially free of a cation exchange resin that comprises sulfonic acid groups.

In other respects, the invention relates to processes for producing a polyether polyol. These processes comprise: (a) adding an alkylene oxide onto an H-functional starter in the presence of an alkali metal catalyst to produce an alkali metal-containing crude polyol comprising a mixture comprising the polyether polyol and alkali metal ions; (b) passing the mixture through a first bed comprising a cation exchange resin comprising carboxylic acid and/or phosphonic acid groups to remove alkali metal ions from the mixture; and (c) passing the product of step (b) through a second bed comprising an anion exchange resin comprising quaternary ammonium groups and a cation exchange resin comprising carboxylic acid and/or phosphonic acid groups, wherein the first bed and the second bed are each substantially free of a cation exchange resin that comprises sulfonic acid groups.

The present specification also describes, among other things, systems for conducting such processes, polyether polyols purified by such processes, and polyurethanes, such as polyurethane foams, produced from such polyether polyols.

Various embodiments are described and illustrated in this specification to provide an overall understanding of the structure, function, properties, and use of the disclosed inventions. It is understood that the various embodiments described and illustrated in this specification are non-limiting and non-exhaustive. Thus, the invention is not limited by the description of the various non-limiting and non-exhaustive embodiments disclosed in this specification. The features and characteristics described in connection with various embodiments may be combined with the features and characteristics of other embodiments. Such modifications and variations are intended to be included within the scope of this specification. The various embodiments disclosed and described in this specification can comprise, consist of, or consist essentially of the features and characteristics as variously described herein.

Numerical parameters disclosed in this specification possess the inherent variability characteristic of the underlying measurement techniques used to determine the numerical value of the parameter. At the very least, each numerical parameter described in the present description should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Also, any numerical range recited in this specification is intended to include all sub-ranges of the same numerical precision subsumed within the recited range. For example, a range of "<NUM> to <NUM>" is intended to include all sub-ranges between (and including) the recited minimum value of <NUM> and the recited maximum value of <NUM>, that is, having a minimum value equal to or greater than <NUM> and a maximum value equal to or less than <NUM>, such as, for example, <NUM> to <NUM>. Any maximum numerical limitation recited in this specification is intended to include all lower numerical limitations subsumed therein and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. All such ranges are intended to be inherently described in this specification.

The grammatical articles "one", "a", "an", and "the", as used in this specification, are intended to include "at least one" or "one or more", unless otherwise indicated. Thus, the articles are used in this specification to refer to one or more than one (i.e., to "at least one") of the grammatical objects of the article. By way of example, "a component" means one or more components, and thus, possibly, more than one component is contemplated and may be employed or used in an implementation of the described embodiments. Further, the use of a singular noun includes the plural, and the use of a plural noun includes the singular, unless the context of the usage requires otherwise.

As indicated, in certain embodiments, the present specification is directed to processes for removing alkali metal ions from polyether polyols. Such removal of alkali metal ions may sometimes be referred to herein as "purifying" the polyether polyol. The term "polyether polyol" encompasses polyether ester polyols.

The invention is as indicated in the claims.

The polyether polyols subject to the methods of this specification can be prepared by adding one or more alkylene oxides having <NUM> to <NUM> carbon atoms, such as <NUM> to <NUM> carbon atoms, in the alkylene radical, and which are optionally substituted, to a H-functional starter molecule that contains at least <NUM>, such as <NUM> to <NUM>, or, in some cases, <NUM> to <NUM>, active hydrogen atoms, in the presence of an alkaline catalyst.

The methods of the present specification are suitable for removing water and alkali metal ions from a wide range of polyols, in terms of their functionality, molecular weight and hydroxyl (OH) number. For example, the polyether polyols have a number average molecular weight of at least <NUM> gram/mole, such as at least <NUM> gram/mole, in some cases <NUM> gram/mole to <NUM>,<NUM> gram/mole, or, in some cases, <NUM> to <NUM>,<NUM> gram/mole, and a hydroxyl number of <NUM> to <NUM> KOH/gram, such as <NUM> to <NUM> KOH/gram.

In some implementations, however, the methods of this specification are particularly advantageous for use in connection with removing alkali metal ions from "long chain" polyether polyols, that is, polyether polyols that have a relatively low hydroxyl number. More specifically, in some implementations, the "long chain" polyether polyol has a hydroxyl number of no more than <NUM> KOH/gram, such as <NUM> to <NUM> KOH/gram, <NUM> to <NUM> KOH/gram, <NUM> to <NUM> KOH/gram, or, in some embodiments, <NUM> to <NUM> KOH/gram. As used herein, the term "hydroxyl number" refers to the number of reactive hydroxyl groups available for reaction, is expressed as the number of milligrams of potassium hydroxide equivalent to the hydroxyl content of one gram of the polyol, and is measured according to ASTM D4274-<NUM>. In addition, in some implementations, the "long chain" polyether polyol has a calculated number average molecular weight of at least <NUM> gram/mole, such as <NUM> to <NUM>,<NUM> gram/mole, <NUM> to <NUM> gram/mole, <NUM> to <NUM> gram/mole, in some cases, <NUM> to <NUM> gram/mole. The calculated number average molecular weights of the polyols described herein are calculated from the polyol's functionality and hydroxyl number according to the equation: <MAT> in which f is the functionality of the polyol (the number of hydroxyl groups per molecule), OH# is the hydroxyl number of the polyol and is equal to the mass in milligrams of potassium hydroxide (<NUM> grams/mol) equivalent to the hydroxyl content in one gram of the polyol compound (mg KOH/g), and Mn is the number average molecular weight of the polyol. The polyol functionality referred to herein is the theoretical average nominal functionality of the polyol, that is, the functionality calculated based on the average number of hydroxyl groups per molecule of starter used to produce the polyol.

In addition, in some implementations, the polyol produced by processes of this specification has an acid number of less than <NUM> KOH/g, such as less than <NUM> KOH/g, or, in some cases, less than <NUM> KOH/g. The acid number of the polyol can be measured according to ASTM D7253-<NUM>.

As indicated, the polyether polyols described in this specification are alkali metal catalyzed alkoxylation reaction products of an alkylene oxide and an H-functional starter. Alkylene oxides suitable for use in preparing such polyether polyols include, for example, ethylene oxide, propylene oxide, <NUM>-butene oxide, <NUM>,<NUM>-butene oxide, <NUM>-methyl-<NUM>,<NUM>-propene oxide (isobutene oxide), <NUM>-pentene oxide, <NUM>,<NUM>-pentene oxide, <NUM>-methyl-<NUM>,<NUM>-butene oxide, <NUM>-methyl-<NUM>,<NUM>-butene oxide, <NUM>-hexene oxide, <NUM>,<NUM>-hexene oxide, <NUM>,<NUM>-hexene oxide, <NUM>-methyl-<NUM>,<NUM>-pentene oxide, <NUM>-methyl-<NUM>,<NUM>-pentene oxide, <NUM>-ethyl-<NUM>,<NUM>-butene oxide, <NUM>-heptene oxide, <NUM>-octene oxide, <NUM>-nonene oxide, <NUM>-decene oxide, <NUM>-undecene oxide, <NUM>-dodecene oxide, <NUM>-methyl-<NUM>,<NUM>-pentene oxide, butadiene monoxide, isoprene monoxide, cyclopentene oxide, cyclohexene oxide, cycloheptene oxide, cyclooctene oxide, styrene oxide, methylstyrene oxide and pinene oxide. In some implementations ethylene oxide (EO) and/or propylene oxide (PO) is used. More particularly, in some implementations, a ratio of EO and PO, based on the amount of alkylene oxide used, is between <NUM>% by weight of EO/<NUM>% by weight of PO and <NUM>% by weight of EO /<NUM>% by weight of PO. In addition to the alkylene oxides, it is also possible to use other comonomers which can be added individually or in a mixture with the alkylene oxides. The various alkylene oxides and any other comonomers can be metered in a mixture or in blocks. Ethylene oxide can be metered in, for example, in a mixture with other alkylene oxides or in blocks as a starting, middle or end block.

As used in this specification, "H-functional starter" refers to compounds having Zerewitinoff-active hydrogen atoms, such as <NUM> to <NUM> such hydrogen atoms, and, in some implementations, a molar mass of <NUM>/mol to <NUM>/mol, such as <NUM> to <NUM>/mol, or <NUM> to <NUM>/mol. Exemplary Zerewitinoff-active hydrogen atoms are -OH, -NH<NUM> (primary amines), -NH-(secondary amines), -SH, and -CO<NUM>H.

Specific examples of suitable OH-functional starter compounds are methanol, ethanol, <NUM>-propanol, <NUM>-propanol and higher aliphatic monols, such as fatty alcohols, phenol, alkylsubstituted phenols, propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol, butane-<NUM>,<NUM>-diol, butane-<NUM>,<NUM>-diol, butane-<NUM>,<NUM>-diol, hexanediol, pentanediol, <NUM>-methylpentane-<NUM>,<NUM>-diol, dodecane-<NUM>,<NUM>-diol, water, glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol, sucrose, hydroquinone, catechol, resorcinol, bisphenol F, bisphenol A, <NUM>,<NUM>,<NUM>-trihydroxybenzene, methylol-containing condensates of formaldehyde and phenol or melamine or urea, and Mannich bases. In some cases, the OH-functional starter may include a polycyclic polyol starter, such as any of the bicyclic polyols, tricyclic polyols, and polyols that include four or more rings per molecule, as are described in <CIT> at col. <NUM>, line <NUM> to col. <NUM>, line <NUM>.

Examples of suitable starter compounds containing amino groups are ammonia, ethanolamine, diethanolamine, isopropanolamine, diisopropanolamine, ethylenediamine, hexamethylenediamine, aniline, the isomers of toluidine, the isomers of diaminotoluene, the isomers of diaminodiphenylmethane, and higher polycyclic products obtained in the condensation of aniline with formaldehyde to give diaminodiphenylmethane. In addition, starter compounds used may also be ring-opening products of cyclic carboxylic anhydrides and polyols. Examples are ring-opening products of phthalic anhydride, succinic anhydride and maleic anhydride on the one hand, and ethylene glycol, diethylene glycol, butane-<NUM>,<NUM>-diol, butane-<NUM>,<NUM>-diol, butane-<NUM>,<NUM>-diol, hexanediol, pentanediol, <NUM>-methylpentane-<NUM>,<NUM>-diol, dodecane-<NUM>,<NUM>-diol, glycerol, trimethylolpropane, pentaerythritol or sorbitol on the other hand. Ring-opening products of this kind can also be prepared in situ directly prior to the start of the alkylene oxide addition reaction in the polymerization reactor. In addition, it is also possible to use mono- or polyfunctional carboxylic acids directly as starter compounds. It is also possible to use mixtures of various H-functional starters.

An alkali metal ion-containing catalyst is used in the preparation of the polyether polyols that are the subject of the processes of this specification. Suitable catalysts are, for example, alkali metal hydrides, alkali metal carboxylates (for example those of monofunctional carboxylic acids), alkali metal hydroxides and alkali metal alkoxylates. Suitable alkali metal hydroxides include, for example, sodium hydroxide, potassium hydroxide or cesium hydroxide, and suitable alkali metal alkoxylates include alkali metal alkoxylates of mono- or polyfunctional alcohols. As the latter, it is also possible to use previously prepared alkylene oxide addition products of starter compounds containing Zerewitinoff-active hydrogen atoms having alkoxylate contents of <NUM>% to <NUM>% in terms of equivalents ("polymeric alkoxylates"). The alkoxylate content of the catalyst is understood to mean the proportion of Zerewitinoff-active hydrogen atoms removed by deprotonation by a base AOH (A=alkali metal) of all the Zerewitinoff-active hydrogen atoms that were originally present in the alkylene oxide addition product of the catalyst. The amount of the polymeric alkali metal alkoxylate used is guided by the catalyst concentration desired, and expressed as the concentration of AOH.

In some implementations, the alkali metal ion-containing catalyst is used in an amount of <NUM> to <NUM> weight percent, <NUM> to <NUM> weight percent, <NUM> to <NUM> weight percent, or, in some cases, <NUM> to <NUM> weight percent, based on the total weight of polyether polyol.

The catalyst can be supplied to the starter compound, for example, as a pure substance (often solids) or as an aqueous solution. By means of a stripping step preceding the alkylene oxide metering, water of dissolution and the water which arises, for example, through the reaction of the alkali metal hydroxides with the Zerewitinoff-active hydrogen atoms in the starter compounds may be removed. If, in the case of alkali metal hydroxide catalysis, aqueous solutions of starter compounds solid at room temperature are used, it may be appropriate to perform only one stripping step, for example, before commencement of the actual alkylene oxide addition phase or, if desired, after interruption of an already running alkylene oxide addition reaction.

In some embodiments, the starter compound is reacted with the alkylene oxide(s) at a temperature of <NUM> to <NUM>, such as <NUM> to <NUM>. Post-reactions can likewise be performed at higher temperatures (such as after raising the temperature to <NUM> to <NUM> or <NUM> to <NUM>. In the case of "long-chain" polyols, it may be desirable, in the case of attainment of high equivalent molar masses and in the case of metered addition of blocks having high contents of oxypropylene units, for example at <NUM> Da or higher equivalent molar masses, to restrict the reaction temperature to values of <NUM>, or <NUM> or less, in order to reduce side reactions of the propylene oxide, especially the rearrangement thereof to allyl alcohol. Equivalent molar mass is understood to mean the number-average total molar mass of the material containing active hydrogen atoms divided by the number of active hydrogen atoms (functionality). The extent of these side reactions increases with the content of propylene oxide in the alkylene oxide mixture metered in; therefore, the restriction in the reaction temperature may gain importance when the propylene oxide content in the alkylene oxide mixture metered in exceeds values of <NUM>% by weight, <NUM>% by weight, or <NUM>% by weight. The metered addition of blocks having high contents of oxyethylene units or blocks consisting purely of oxyethylene units, as well as post-reactions, can in turn be performed at higher temperatures (such as after raising the temperature to <NUM> to <NUM> or <NUM> to <NUM>).

In some cases, it may be necessary or desirable to keep the temperature of the exothermic alkylene oxide addition reaction at the desired level by cooling. Suitable such cooling can generally be affected via the reactor wall (such as with a cooling jacket or half-coil pipe) and by means of further heat exchange surfaces disposed internally in the reactor and/or externally in the pumped circulation system, for example in cooling coils, cooling cartridges, or plate, shell-and-tube or mixer heat exchangers.

Further information regarding suitable equipment and procedural aspects of producing polyether polyols of the type involved in this specification can be found in <CIT> at col. <NUM>, line <NUM> to col. <NUM>, line <NUM>.

In some embodiments of the processes of this specification, the alkali-metal ion containing catalyst and polyether polyol are, prior to purification of the polyether polyol, present in a mixture that also includes water. In certain embodiments, prior to any purification of the polyether polyol, water is present in such a mixture in an amount of at least <NUM>% by weight, at least <NUM>% by weight, or, in some cases, at least <NUM>% by weight and up to <NUM>% by weight, such as up to <NUM>% by weight, up to <NUM>% by weight, or up to <NUM>% by weight, based on the total weight of polyether polyol present.

In some implementations, a mixture comprising water and a polar organic solvent ("First Mixture") is combined with a mixture comprising a polyether polyol and an alkali metal ion-containing catalyst ("Second Mixture"). Suitable polar organic solvents include, for example, C<NUM> to C<NUM> alkyl alcohols, such as methanol, ethanol, propanol, isopropanol, butanol, and tert-butanol, including mixtures thereof. In certain embodiments, the First Mixture is added in an amount of <NUM> to <NUM>% by weight, based on the total weight of the First Mixture and the Second Mixture. In some embodiments, the relative weight ratio of polar organic solvent and water in the First Mixture is within a range of <NUM>:<NUM> to <NUM>:<NUM>, such as <NUM>:<NUM> to <NUM>:<NUM>, or, in some cases <NUM>:<NUM> to <NUM>:<NUM>.

According to processes of this specification, a mixture comprising the polyether polyol and the alkali metal ions, which mixture may comprise a combination of the First Mixture and the Second Mixture described above, is passed through a first bed comprising a cation exchange resin comprising carboxylic acid and/or phosphonic acid groups to remove alkali metal ions from the mixture. More specifically, in some implementations, the foregoing mixture is passed through a bed comprising the cation exchange resin that is disposed in a container, such as a column, in order to remove alkali metal ion from the mixture. Suitable cation exchange resins include those of the gel type and those of the porous type and include resins having carboxylic acid groups (-COOH) and/or phosphonic acid groups (-H<NUM>O<NUM>P), such as, for example, those based on crosslinked polystyrene, including, without limitation, copolymers of styrene and divinylbenzene with phosphonic acid groups and/or carboxylic acids groups, as well as (meth)acrylic acid functional polymers. As used herein, the term "(meth)acrylic" is meant to encompass methacrylic and acrylic. Suitable cation exchange resins are commercially available and include, for example, those under the tradenames Amberlite™ (Dow), Lewatit® (Lanxess), Dowex™ (Dow), Diaion™ (Mitsubishi Chemical), and Relite™ (Resindion), to name a few. In certain embodiments of the processes of the present specification, the first bed comprising cation exchange resin has a volume of at least <NUM> cubic feet (<NUM> cubic meter), such as at least <NUM> cubic feet (<NUM> cubic meters), such as <NUM> to <NUM> cubic feet (<NUM> to <NUM> cubic meters), <NUM> to <NUM> cubic feet (<NUM> to <NUM> cubic meters), <NUM> to <NUM> cubic feet (<NUM> to <NUM> cubic meters), or, in some cases, <NUM> to <NUM> cubic feet (<NUM> to <NUM> cubic meters).

In certain embodiments, the product of the foregoing combining step is passed through the first bed of cation exchange resin at a resin bed temperature of <NUM> to <NUM>, such as <NUM> to <NUM>, and/or at a container pressure of <NUM> to <NUM> pounds per square inch [absolute] (<NUM> to <NUM> kilopascal), such as <NUM> to <NUM> pounds per square inch (<NUM> to <NUM> kilopascal). In certain embodiments, the crude polyether polyol that enters the first bed has a content of alkali metal ion of at least <NUM>% by weight, such as <NUM> to <NUM>% by weight, based on the total weight of polyether polyol present. In certain embodiments, the purified polyether polyol that exits the first bed has an alkali metal ion content of no more than <NUM> ppm, such as no more than <NUM> ppm, no more than <NUM> ppm, or, in some cases, no more than <NUM> ppm, based on total weight of polyether polyol present.

In some implementations, the container, such as column, that includes the first bed is operated in a liquid-full manner throughout the process. As used herein, when it is stated that the container is operated "liquid-full" it means that the liquid level in the container in which the cation exchange resin is disposed is maintained such that there is little or no gas/liquid interface in the container and/or that the liquid level is maintained above the level of the bed of cation exchange resin. In some embodiments, therefore, the liquid level is maintained at a level that is at least <NUM>% of the total container height throughout the process, such as at least <NUM>% of the total container height, or, in yet other cases, at least <NUM>% of the total container height, in each case throughout the process. In some embodiments, the liquid level is maintained at <NUM>% of the total container height throughout the process and, as such, in these embodiments of the process there is no gas/liquid interface in the container. In some embodiments, no gas is added to the container to maintain a gas/liquid interface and/or the rate at which liquid is pumped out of the container is not controlled to maintain a gas/liquid interface in the container. Rather, in some embodiments, liquids are moved through the container by virtue of feed pressure to the container, such as pump pressure or other pressure sources, thereby eliminating, or at least virtually eliminating, back mixing of the polyether polyol. As used herein, "throughout the process" means that the container is maintained liquid-full continuously while the polyether polyol mixture is passed there through for the purpose of removing alkali metal ions therefrom.

According to the processes of this specification, the purified polyether polyol that exits the first bed is thereafter passed through a second bed comprising an anion exchange resin comprising quaternary ammonium groups and a cation exchange resin comprising carboxylic acid and/or phosphonic acid groups. The second bed is thus a so-called "mixed bed".

As with the first bed, suitable cation exchange resins for use in the second bed include those of the gel type and those of the porous type and include resins having carboxylic acid groups (-COOH) and/or phosphonic acid groups (-H<NUM>O<NUM>P), such as, for example, those based on crosslinked polystyrene, including, without limitation, copolymers of styrene and divinylbenzene with phosphonic acid groups and/or carboxylic acids groups, as well as (meth)acrylic acid functional polymers. Suitable anion exchange resins for use in the second bed also include those of the gel type and those of the porous type and include resins having quaternary ammonium groups, such as trimethylammonium groups. Suitable anion exchange resins include, without limitation, those based on crosslinked polystyrene.

Suitable cation exchange resins and anion exchange resins for use in the second bed are commercially available and include, for example, those under the tradenames Amberlite™ (Dow), Lewatit® (Lanxess), Dowex™ (Dow), Diaion™ (Mitsubishi Chemical), and Relite™ (Resindion), to name a few. In certain embodiments of the processes of the present specification, the second bed has a volume of at least <NUM> cubic feet (<NUM> cubic meter), such as at least <NUM> cubic feet (<NUM> cubic meters), such as <NUM> to <NUM> cubic feet (<NUM> to <NUM> cubic meters), <NUM> to <NUM> cubic feet (<NUM> to <NUM> cubic meters), <NUM> to <NUM> cubic feet (<NUM> to <NUM> cubic meters), or, in some cases, <NUM> to <NUM> cubic feet (<NUM> to <NUM> cubic meters).

In certain embodiments, the purified polyether polyol that exits the first bed is passed through the second bed at a resin bed temperature of <NUM> to <NUM>, such as <NUM> to <NUM>, and/or at a container pressure of <NUM> to <NUM> pounds per square inch [absolute] (<NUM> to <NUM> kilopascal), such as <NUM> to <NUM> pounds per square inch (<NUM> to <NUM> kilopascal).

Further, in some implementations, the container, such as column, that includes the second bed is also operated in a liquid-full manner throughout the process. In some embodiments, therefore, the liquid level is maintained at a level that is at least <NUM>% of the total container height throughout the process, such as at a level that is at least <NUM>% of the total container height, or, in yet other cases, at a level that is at least <NUM>% of the total container height, in each case throughout the process. In some embodiments, the liquid level is maintained at <NUM>% of the total container height throughout the process and, as such, in these embodiments of the process there is no gas/liquid interface in the container. In some embodiments, no gas is added to the container to maintain a gas/liquid interface and/or the rate at which liquid is pumped out of the container is not controlled to maintain a gas/liquid interface in the container. Rather, in some embodiments of the process, liquids are moved through the container by virtue of feed pressure to the container, such as pump pressure or other pressure sources, thereby eliminating, or at least virtually eliminating, back mixing of the polyether polyol.

In the processes of this specification, the first bed and the second bed are each substantially or, in some cases, completely free of a strong cation exchange resin, that is, a cation exchange resin that comprises sulfonic acid groups. As used herein, "substantially free" when used with reference to the presence of a strong cation exchange resin in each of the first bed and the second bed, means that strong cation exchange resin is present in the bed an amount of no more than <NUM>% by weight, no more than <NUM>% by weight, or, in some cases, no more than <NUM>% by weight, based on the total weight of ion exchange resin present in the bed. Thus, in accordance with the present invention, (i) both beds are free (i.e. completely free) of a strong cation exchange resin, or (ii) one bed is free (i.e. completely free) of a strong cation exchange resin and the other bed contains a strong cationic resin, albeit in an amount of no more than <NUM>% by weight, no more than <NUM>% by weight, or, in some cases, no more than <NUM>% by weight, based on the total weight of ion exchange resin present in the bed, or (iii) both beds contain a strong cation exchange resin, albeit in an amount of no more than <NUM>% by weight, no more than <NUM>% by weight, or, in some cases, no more than <NUM>% by weight, based on the total weight of ion exchange resin present in the bed.

After passing through the container comprising the second bed, the purified polyether polyol is often further processed to remove organic solvent and water. Such further processing often involves distillation, including distillation under at least atmospheric and/or vacuum conditions, either of which may be carried out batchwise or continuously. In some embodiments, for example, a combination of at least atmospheric distillation and vacuum distillation is used.

For example, in some embodiments, the at least atmospheric distillation step is used to remove a portion of the water and/or organic solvent under at least atmospheric pressure. As used herein, "atmospheric pressure" is synonymous with barometric pressure and refers to the pressure exerted by the weight of the atmosphere in the location in which the purified polyether polyol is disposed. In certain embodiments, for this at least atmospheric distillation, the temperature of the polyether polyol is maintained at <NUM> to <NUM>, such as <NUM> to <NUM>. In certain embodiments, the at least atmospheric distillation is conducted at a pressure above atmospheric pressure, such as up to <NUM> psia (<NUM> kPa).

In some embodiments, an evaporator removes additional water and/or organic solvent from the polyether polyol under vacuum. Transition to the vacuum distillation step includes reducing the pressure to a range of <NUM> mmHg to <NUM> mmHg, and, in some embodiments, to a temperature of <NUM> to <NUM>. In some implementations, steam is sparged sub-surface to the liquid polyether in a flash tank evaporator under vacuum using a pipe sparger to evenly distribute the steam through the polyether polyol. For example, in some implementations, steam is sparged at a rate that results in a weight ratio of steam to polyol of at least <NUM>: <NUM>, such as at least <NUM>: <NUM>. In some cases, the steam may assist in the removal of 2M2P, isopropanol and aldehydes from the polyether polyol. Water injection can be similarly effective in assisting the vacuum stripping but requires additional heating to vaporize the water.

In certain embodiments, following distillation, water is present with the polyether polyol in an amount of no more than <NUM>,<NUM> ppm, no more than <NUM>,<NUM> ppm, or no more than <NUM> ppm (when measured according to ASTM D4672 (<NUM>)), based on total weight of polyether polyol.

It was discovered, surprisingly, that the polyether polyol purification processes of this specification, which entail use of a weak cation exchange followed by a mixed weak cation exchange and strong anion exchange, in the substantial absence of a strong cation exchange resin, enables purification of low hydroxyl number polyether polyols of the type described earlier in a manner that results in a purified polyether polyol that, after removal of organic solvent and water (such as by distillation as described above) that has a 2M2P content of no more than <NUM> ppm, such as no more than <NUM> ppm or no more than <NUM> ppm measured by Headspace Gas Chromatography and Mass Spectrometry (HS GC-MS), based on total weight of the polyether polyol present. In some implementations, such a purified polyether polyol may have an acid number of no more than <NUM> KOH/g or no more than <NUM> KOH/g, and a residual alkalinity, determined by visual titration, of no more than <NUM> meq/kg or no more than <NUM> meq/kg, measured according to ASTM D7253-<NUM>.

The 2M2P amounts referred to herein are measured by Headspace Gas Chromatography and Mass Spectrometry (HS GC-MS). HS GC-MS can be conducted using an Agilent 7697A Headspace Sampler using headspace conditions of: Oven Temperature: <NUM>, Loop Temperature: <NUM>, Transfer Line Temperature: <NUM>, Vial Equilibration: <NUM> minutes, Injection Time: <NUM> minutes, GC Cycle Time: <NUM> minutes, Vial Size: <NUM>, and Fill Pressure: 10psi, and GC MS conditions of: Column: RTX-<NUM><NUM> x <NUM> x <NUM>, Carrier Gas: Helium, Flow: <NUM>/min, constant, Oven Profile: <NUM> hold <NUM> and <NUM>/min to <NUM> hold <NUM>, Run Time: <NUM> minutes, Injection Temp: <NUM>, Injection Mode: Split <NUM>:<NUM>, MS Mode: ei Scan, Mass Range: <NUM>-<NUM>, MS source: <NUM>, and MS Quad: <NUM>. The measurement sample is prepared by weighing <NUM> grams of the sample into a <NUM> headspace vial and adding 50µL of a solution of <NUM> ppm <NUM>,<NUM>-dioxane in propylene carbonate.

Regeneration of the exchange resins is eventually necessary with the processes of the present invention. It is sometimes desirable to analytically measure the alkali metal-ion content in the effluent from the first bed to determine when regeneration is necessary. Regeneration of the cation exchange resin can be done by treating the resin with an acid, such as hydrochloric acid and/or sulfuric acid, though other mineral acids can be used. In some embodiments, an acid solution having acid concentration of <NUM> to <NUM>% by weight, such as <NUM> to <NUM>% by weight is used.

The polyether polyols purified by the processes of the present specification may be used in a variety of applications. For example, such polyether polyols may be reacted with one or more isocyanates to provide polyurethane products including, but not limited to, coatings, adhesives, sealants, elastomers, foams, including flexible foams, and the like. Suitable organic polyisocyanates for forming such polyurethanes include unmodified isocyanates, modified polyisocyanates, and isocyanate prepolymers. Such organic polyisocyanates include aliphatic, cycloaliphatic, araliphatic, aromatic, and heterocyclic polyisocyanates of the type described, for example, by <NPL>. Examples of such isocyanates include those represented by the formula:.

in which n is a number from <NUM>-<NUM>, such as <NUM>-<NUM>, and Q is an aliphatic hydrocarbon group; a cycloaliphatic hydrocarbon group; an araliphatic hydrocarbon group; or an aromatic hydrocarbon group.

The non-limiting and non-exhaustive examples that follow are intended to further describe various non-limiting and non-exhaustive embodiments without restricting the scope of the claims.

<NUM> of a crude glycerin-based polyether polyol with a nominal hydroxyl number of <NUM> KOH/g and a potassium concentration of <NUM> wt% on a KOH basis was mixed with a solution of isopropanol and water to make a mixture of <NUM> wt% polyether polyol, <NUM> wt% isopropanol and <NUM> wt% water. This mixture was fed to two ion exchange beds arranged in series at a temperature of <NUM>-<NUM> at a rate of <NUM>-<NUM> bed volumes per hour. The first bed contained a weak acid resin, (e.g. Lanxess CNP <NUM>, Purolite PPC-104Plus, Amberlite HPR <NUM>-H, etc.) and the second bed contained a <NUM>/<NUM> mixture (by weight) of strong acid resin, Amberlite HPR <NUM>-H and anion resin, Amberlite IRA <NUM>-OH (standard mixed bed). The mixture was collected in a heated flask after the ion exchange beds and heated to <NUM>-<NUM>. The flask was maintained under vacuum (<NUM>-<NUM> Hg) to remove isopropanol and water from the mixture. After stripping for sufficient time (typically > <NUM> hours) to reach a water concentration of ≤ <NUM> wt%, a standard antioxidant such as Irganox <NUM>, was added to the purified product. The volatile content of the purified polyol was then measured by headspace GC-MS and <NUM> ppm <NUM>-Methyl-<NUM>-Pentenal (2M2P) was found in the sample.

The same crude polyol described in Example <NUM> was used to make a mixture of <NUM> wt% polyether polyol, <NUM> wt% isopropanol and <NUM> wt% water. This mixture was fed to two ion exchange beds arranged in series at a temperature of <NUM>-<NUM> at a rate of <NUM>-<NUM> bed volumes per hour. The first bed contained a weak acid resin, (e.g. Lanxess CNP <NUM>, Purolite PPC-104Plus, Amberlite HPR <NUM>-H, etc.) and the second bed contained a <NUM>/<NUM> mixture (by weight) of weak acid resin, Amberlite HPR <NUM>-H and anion resin, Amberlite IRA <NUM>-OH. The mixture was collected in a heated flask after the ion exchange beds and heated to <NUM>-<NUM>. The flask was maintained under vacuum (<NUM>-<NUM> Hg) to remove isopropanol and water from the mixture. After stripping for sufficient time (typically > <NUM> hours) to reach a water concentration of ≤ <NUM> wt%, a standard antioxidant, such as Irganox <NUM>, was added to the purified product. The volatile content of the purified polyol was then measured by headspace GC-MS and <<NUM> ppm <NUM>-Methyl-<NUM>-Pentenal (2M2P) was found in the sample.

The same crude polyol described in Example <NUM> was used to make a mixture of <NUM> wt% polyether polyol, <NUM> wt% isopropanol and <NUM> wt% water. This mixture was fed to two ion exchange beds arranged in series at a temperature of <NUM>-<NUM> at a rate of <NUM>-<NUM> bed volumes per hour. The first bed contained a weak acid resin, (e.g. Lanxess CNP <NUM>, Purolite PPC-104Plus, Amberlite HPR <NUM>-H, etc.) and the second bed contained a <NUM>/<NUM>/<NUM> mixture (by weight) of weak acid resin, Amberlite HPR <NUM>-H, strong acid resin, Amberlite HPR <NUM>-H and anion resin, Amberlite IRA <NUM>-OH. The mixture was collected in a heated flask after the ion exchange beds and heated to <NUM>-<NUM>. The flask is maintained under vacuum (<NUM>-<NUM> Hg) to remove the isopropanol and water from the mixture. After stripping for sufficient time (typically > <NUM> hours) to reach a water concentration of ≤ <NUM> wt%, a standard antioxidant, such as Irganox <NUM>, was added to the purified product. The volatile content of the purified polyol was then measured by headspace GC-MS and <NUM> ppm <NUM>-Methyl-<NUM>-Pentenal (2M2P) was found in the sample.

The same crude polyol described in Example <NUM> was used to make a mixture of <NUM> wt% polyether polyol, <NUM> wt% isopropanol and <NUM> wt% water. This mixture was fed to two ion exchange beds arranged in series at a temperature of <NUM>-<NUM> at a rate of <NUM>- <NUM> bed volumes per hour. The first bed contained a weak acid resin, (e.g. Lanxess CNP <NUM>, Purolite PPC-104Plus, Amberlite HPR <NUM>-H, etc.) and the second bed contained a <NUM>/<NUM>/<NUM> mixture (by weight) of weak acid resin, Amberlite HPR <NUM>-H, strong acid resin, Amberlite HPR <NUM>-H and anion resin, Amberlite IRA <NUM>-OH. The mixture was collected in a heated flask after the ion exchange beds and heated to <NUM>-<NUM>. The flask was maintained under vacuum (<NUM>-<NUM> Hg) to remove isopropanol and water from the mixture. After stripping for sufficient time (typically > <NUM> hours) to reach a water concentration of ≤ <NUM> wt%, a standard antioxidant, such as Irganox <NUM>, was added to the purified product. The volatile content of the purified polyol was then measured by headspace GC-MS and <NUM> ppm <NUM>-Methyl-<NUM>-Pentenal (2M2P) was found in the sample.

The same crude polyol described in Example <NUM> was used to make a mixture of <NUM> wt% polyether polyol, <NUM> wt% isopropanol and <NUM> wt% water. The mixture was fed to two ion exchange beds arranged in series at a temperature of <NUM>-<NUM> at a rate of <NUM>-<NUM> bed volumes per hour. The first bed contained a weak acid resin, (e.g. Lanxess CNP <NUM>, Purolite PPC-104Plus, Amberlite HPR <NUM>-H, etc.) and the second bed contained a <NUM>/<NUM>/<NUM> mixture (by weight) of weak acid resin, Amberlite HPR <NUM>-H, strong acid resin, Amberlite HPR <NUM>-H and anion resin, Amberlite IRA <NUM>-OH. The mixture was collected in a heated flask after the ion exchange beds and heated to <NUM>-<NUM>. The flask was maintained under vacuum (<NUM>-<NUM> Hg) to remove isopropanol and water from the mixture. After stripping for sufficient time (typically > <NUM> hours) to reach a water concentration of ≤ <NUM> wt%, a standard antioxidant, such as Irganox <NUM>, was added to the purified product. The volatile content of the purified polyol was then measured by headspace GC-MS and <NUM> ppm <NUM>-Methyl-<NUM>-Pentenal (2M2P) was found in the sample.

Claim 1:
A process for removing alkali metal ions from a polyether polyol, comprising:
(a) passing a mixture comprising the polyether polyol and the alkali metal ions through a first bed comprising a cation exchange resin comprising carboxylic acid and/or phosphonic acid groups to remove alkali metal ions from the mixture; and
(b) passing the product of step (a) through a second bed comprising an anion exchange resin comprising quaternary ammonium groups and a cation exchange resin comprising carboxylic acid and/or phosphonic acid groups to thereby produce a purified polyether polyol,
wherein the first bed and the second bed each do not contain any cation exchange resin that comprises sulfonic acid groups or contain a cation exchange resin that comprises sulfonic acid groups in an amount of no more than <NUM>% by weight, based on the total weight of ion exchange resin used in the first bed and second bed, respectively.