EP4713380A1

EP4713380A1 - Process for treatment of polyether alcohol prepared using double metal cyanide catalyst

Info

Publication number: EP4713380A1
Application number: EP24725128.3A
Authority: EP
Inventors: Paul Davis; Sandip Shripad Talwalkar; Prashant Anil Tatake; Rama Tejaswi KARIPEDDI
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 2023-05-18
Filing date: 2024-05-07
Publication date: 2026-03-25
Also published as: CN121127515A; WO2024235747A1

Abstract

The invention relates to a process for treatment of a polyether alcohol, comprising : providing a polyether alcohol prepared using a composite metal cyanide complex catalyst; contacting the polyether alcohol with an adsorbent, the adsorbent having a volume-average particle size greater than 20 pm, in an adsorbent bed comprising a powder of the adsorbent, wherein at lea st part of the polyether alcohol is not contacted with the adsorbent before the polyether alcohol contacts the adsorbent in the adsorbent bed.

Description

cyanide complex catalyst (also referred to as double metal cyanide (DMC) catalyst), to the polyether alcohol obtainable by said process, to a process for preparing a polyurethane 10 foam using said polyether alcohol, to the polyurethane foam obtainable by said process, and to a shaped article comprising said polyurethane foam. Background of the invention Polyether alcohols, such as polyether polyols, are 15 commonly used for the manufacture of polyurethane foams, such as flexible polyurethane foams, which have found extensive use in a multitude of industrial and consumer applications. Polyether alcohols are also frequently referred to as polyoxyalkylene alcohols. Polyether alcohols are typically 20 obtained by reacting a starter compound or initiator having one active hydrogen atom or a plurality of active hydrogen atoms, such as glycerol, with one or more alkylene oxides, such as ethylene oxide and propylene oxide. Known suitable catalysts for this reaction comprise composite metal cyanide 25 complex catalysts, which are frequently also referred to as double metal cyanide (DMC) catalysts. Advantages associated with DMC-catalysed production of polyether alcohols is that it is faster and more efficient than the traditional process using potassium hydroxide (KOH) 30 as catalyst. Further, the DMC-catalysed process is more environmentally friendly and has a decreased carbon (CO2) footprint. However, a DMC-catalysed alcohol may be unstable in that at some point after it has been prepared, it may separate into multiple layers. Disadvantageously, because of such phase separation the storage stability of the 5 polyether alcohol is low and the polyether alcohol would have to be used relatively soon after it has been prepared. For in case of phase separation, the different phases will behave differently (different reactivity), for example when reacting the polyether alcohol with a polyisocyanate in order to 10 produce a polyurethane foam. It is desired to prevent such difference and inconsistency in reactivity over time, and hence to provide a polyether alcohol having a high long-term (storage) stability. Further, it is desired that DMC-catalysed polyether 15 alcohols perform well when they are reacted with polyisocyanates in order to produce polyurethane foams. When preparing a polyurethane foam using a DMC-catalysed polyether alcohol, the foam thus produced may be unstable, in specific as shown by a so-called “sink back” of the foam and/or by a 20 relatively low foam height (low foam rise) and/or even by a collapse of the foam. Said sink back refers to a phenomenon wherein after reaching a certain height the foam height is reduced. A disadvantage of such sink back is that the final foam density is not distributed evenly and/or that the final 25 foam height is relatively low. Still further, it is desired that for DMC-catalysed polyether alcohols when reacted with polyisocyanates to produce polyurethane foams, the foam full rise time (foam FRT) is relatively long, especially for viscoelastic (VE) 30 foams. For a longer FRT is indicative of a lower reactivity which, advantageously, may in turn result in less closed cells in the foam and/or a lower remaining amount of unreacted amine intermediate in the foam. Such amine intermediate is formed by of polyisocyanate with water (a blowing agent) which, through a carbamic acid intermediate, results in (i) carbon dioxide which provides the blowing effect and (ii) said amine intermediate which is 5 then to be reacted with polyisocyanate. However, in case of a relatively high reactivity (and hence shorter FRT), the latter reaction may not take place completely. Said amine intermediate has a carcinogenic effect, and hence it is desired to have it reacted with polyisocyanate as completely 10 as possible. It is an object of the present invention to provide a process for treating a polyether alcohol prepared using a DMC catalyst, wherein the treated polyether alcohol has an increased long-term stability which may be evidenced by the 15 absence of phase separation over time as mentioned above, and/or has an increased performance in making polyurethane foams having an increased stability which may be evidenced by not suffering from the above-mentioned disadvantages including foam sink back and/or low foam height and/or foam 20 collapse, and/or can be reacted with polyisocyanates to produce polyurethane foams with a relatively long foam full rise time (FRT). Summary of the invention Surprisingly it was found that one or more of the above 25 objects may be achieved by treatment of a DMC-catalysed polyether alcohol with an adsorbent having a volume-average particle size greater than 20 µm, in a bed comprising a powder of the adsorbent. Accordingly, the present invention relates to a process 30 for treatment of a polyether alcohol, comprising: providing a polyether alcohol prepared using a composite metal cyanide complex catalyst; contacting the polyether with an adsorbent, the adsorbent having a volume-average particle size greater than 20 µm, in an adsorbent bed comprising a powder of the adsorbent, wherein at least part of the polyether alcohol is 5 not contacted with the adsorbent before the polyether alcohol contacts the adsorbent in the adsorbent bed; and separating the polyether alcohol from the adsorbent. Further, the present invention relates to a polyether alcohol obtainable by the above-mentioned process. 10 The present invention also relates to a process for preparing a polyurethane foam comprising reacting a polyether alcohol and a polyisocyanate in the presence of a blowing agent, wherein the polyether alcohol is a polyether alcohol obtained or obtainable by the above-mentioned process. 15 Further, the present invention relates to a polyurethane foam obtainable by the above-mentioned process for preparing a polyurethane foam, and to a shaped article comprising a polyurethane foam obtained or obtainable by said process. Detailed description of the invention 20 While the processes and compositions of the present invention may be described in terms of “comprising”, “containing” or “including” one or more various described steps and components, respectively, they can also “consist essentially of” or “consist of” said one or more various 25 described steps and components, respectively. In the context of the present invention, in a case where a composition comprises two or more components, these components are to be selected in an overall amount not to exceed 100 wt.%. 30 Where upper and lower limits are quoted for a property then a range of values defined by a combination of any of the upper limits with any of the lower limits is also implied. The term “molecular (or “MW”) is used herein to refer to number average molecular weight, unless otherwise specified or context requires otherwise. The number average molecular weight of a polyether alcohol can be measured by 5 gel permeation chromatography (GPC) or vapor pressure osmometry (VPO). The term “hydroxyl (OH) value” or “hydroxyl (OH) number” is used herein to refer to the milligrams of potassium hydroxide equivalent to the hydroxyl content in one gram of 10 polyether alcohol determined by wet method titration. Hence, said OH value or number is expressed in mg KOH/g. The hydroxyl number may be determined according to ASTM D4274. The term “equivalent weight” (or “EW”) is used herein to refer to the weight of polyether alcohol per reactive site. 15 The equivalent weight is 56,100 divided by the hydroxyl value of the polyether alcohol. The term “functionality” or “hydroxyl (OH) functionality” of a polyether alcohol refers to the number of hydroxyl groups per molecule of polyether alcohol. The nominal 20 functionality of a polyether alcohol is the same as that of its starter compound (initiator). Unless indicated otherwise, functionality refers to the actual average functionality which may be lower than the nominal functionality and is determined by the number average molecular weight of the 25 polyether alcohol divided by the equivalent weight of the polyether alcohol. The term “primary hydroxyl content” (or “PHC”) is used herein to refer to the relative proportion (in %) of primary hydroxyl groups in a polyether alcohol based on total number 30 of hydroxyl groups including primary and secondary hydroxyl groups. The primary hydroxyl content may be determined according to ASTM D4273. The terms “ethylene oxide and “propylene oxide content”, respectively, in relation to a polyether alcohol refer to those parts of the polyether alcohol which are derived from ethylene oxide and propylene oxide, respectively. Said contents may also be referred to as oxyethylene content and oxypropylene content, respectively. Further, said contents are based herein on total alkylene oxide weight. The ethylene oxide content may be determined according to ASTM D4875. In the treatment process of the present invention, the polyether alcohol to be treated is a polyether alcohol that has been prepared using a composite metal cyanide complex catalyst. Composite metal cyanide complex catalysts are frequently also referred to as double metal cyanide (DMC) catalysts. A composite metal cyanide complex catalyst is typically represented by the following formula (1): (1) M¹ _a[M² _b(CN)_c]_d.e(M¹ _fX_g).h(H₂0).i(R) wherein each of M¹ and M² is a metal, X is a halogen atom, R is an organic ligand, and each of a, b, c, d, e, f, g, h and i is a number which is variable depending upon the atomic balances of the metals, the number of organic ligands to be coordinated, etc. In the above formula (1), M¹ is preferably a metal selected from Zn(II) or Fe(II). In the above formula, M² is preferably a metal selected from Co(III) or Fe(III). However, other metals and oxidation states may also be used, as is known in the art. In the above formula (1), R is an organic ligand and is preferably at least one compound selected from the group consisting of an alcohol, an ether, a ketone, an ester, an amine and an amide. As such an organic ligand, a water- soluble one may be used. Specifically, one or more compounds selected from tert-butyl alcohol, n-butyl alcohol, iso-butyl alcohol, tert-pentyl alcohol, isopentyl alcohol, N, N- dimethyl acetamide, glyme (ethylene glycol dimethyl ether), diglyme (diethylene glycol dimethyl ether), triglyme (triethylene glycol dimethyl ether), ethylene glycol mono- 5 tert-butylether, iso-propyl alcohol and dioxane, may be used as organic ligand(s). The dioxane may be 1,4-dioxane or 1,3- dioxane and is preferably 1,4-dioxane. Most preferably, the organic ligand or one of the organic ligands in the composite metal cyanide complex catalyst is tert-butyl alcohol. 10 Further, as an alcohol organic ligand, a polyol, preferably a polyether polyol may be used. More preferably, a poly (propylene glycol) having a number average molecular weight in the range of from 500 to 2,500 Dalton, preferably 800 to 2,200 Dalton, may be used as the organic ligand or one of the 15 organic ligands. Most preferably, such poly(propylene glycol) is used in combination with tert-butyl alcohol as organic ligands. The composite metal cyanide complex catalyst can be produced by known production methods. Further, in the present invention, the polyether alcohol 20 to be treated contains ether linkages (or ether units). Further, said polyether alcohol may additionally contain ester linkages (or ester units) and/or carbonate linkages (or carbonate units). It is preferred that said polyether alcohol does not contain ester linkages (or ester units). Further, it 25 is preferred that said polyether alcohol does not contain carbonate linkages (or carbonate units). Still further, said polyether alcohol may consist of ether linkages. Still further, in the present invention, the polyether alcohol to be treated contains one or more hydroxyl groups. 30 Thus, said polyether alcohol may be a polyether monol or a polyether polyol. A monol is an alcohol containing one hydroxyl group, whereas a polyol is an alcohol containing two or more hydroxyl groups. Thus, the polyether to be treated in the process of the present invention has been prepared in the presence of a DMC catalyst. Said polyether alcohol to be treated may still comprise DMC catalyst. Further, DMC catalyst may have 5 been partially or completely removed from said polyether alcohol before the treatment process of the present invention. It is preferred that said polyether alcohol still comprises DMC catalyst. Further, it is preferred that after preparing the polyether alcohol and before treatment in the 10 process of the present invention, the DMC catalyst is not deactivated and/or not removed. The amount of DMC catalyst in said polyether alcohol to be treated in the process of the present invention may be of from 1 to 200 parts per million by weight (ppmw) or of from 5 to 150 ppmw or of from 10 to 15 120 ppmw. The polyether alcohol to be treated in the process of the present invention may be prepared by reacting a starter compound having one or more active hydrogen atoms with an alkylene oxide in the presence of a composite metal cyanide 20 complex catalyst (the DMC catalyst). Preferably, the starter compound used in preparing the polyether alcohol is a polyfunctional alcohol, generally containing from 1 to 8 or 2 to 6 or 2 to 4 hydroxyl groups. Examples of such alcohols comprise n-butanol, allyl alcohol, 25 glycols, glycerol, pentaerythritol, trimethylolpropane, triethanolamine, sorbitol, mannitol and sucrose. Preferably, the starter compound is selected from the group consisting of glycols, glycerol, pentaerythritol, trimethylolpropane, triethanolamine, sorbitol and mannitol. Advantageously, 30 monopropylene glycol (MPG), glycerol or a combination of both may be used as starter compound. Further, the alkylene oxide used in preparing the polyether alcohol may comprise one or more of propylene oxide, ethylene oxide and oxide, preferably propylene oxide and ethylene oxide, most preferably only propylene oxide. The polyether alcohol to be treated in the process of the 5 present invention, comprises polyether chains preferably containing propylene oxide content, optionally butylene oxide content and optionally ethylene oxide content. The propylene oxide content of the polyether alcohol may be at least 10% or at least 20 wt.% or at least 30 wt.% or at 10 least 40% or at least 50 wt.% or at least 60 wt.% or at least 70 wt.% or at least 80 wt.% or at least 90 wt.% or at least 95 wt.% or at least 99 wt.%. Further, the propylene oxide content of the polyether alcohol may be at most 100 wt.% or at most 90 wt.% or at most 80 wt.% or at most 70 wt.% or at 15 most 60 wt.% or at most 50 wt.% or at most 40 wt.% or at most 30 wt.% or at most 20 wt.%. The ethylene oxide content of the polyether alcohol may be 0 wt.% or at least 3 wt.% or at least 5 wt.% or at least 10 wt.% or at least 12 wt.% or at least 15 wt.% or at least 20 20 wt.% or at least 30 wt.% or at least 40% or at least 50 wt.% or at least 60 wt.% or at least 70 wt.% or at least 80 wt.% or at least 90 wt.%. Further, the ethylene oxide content of the polyether alcohol may be at most 90 wt.% or at most 80 wt.% or at most 70 wt.% or at most 60 wt.% or at most 50 wt.% 25 or at most 40 wt.% or below 30 wt.% or at most 25 wt.% or at most 20 wt.% or at most 15 wt.% or at most 12 wt.%. The polyether chains of the polyether alcohol may comprise no ethylene oxide content but may comprise only propylene oxide and/or butylene oxide content, suitably only 30 propylene oxide content. Further, the polyether alcohol may comprise primary hydroxyl groups. The primary hydroxyl content of the polyether alcohol may be 0% or at least 1% or at least 3% or at least 5% or at least 10% or least 20% or at least 30%. Further, the primary hydroxyl content of the polyether alcohol may be at most 90% or at most 80% or at most 70% or at most 60% or at most 50% or at most 40% or at most 30% or 5 at most 20% or at most 15% or at most 10% or at most 5%. Further, the polyether alcohol may have a functionality of from 0.8 to 8, preferably of from 1 to 8, more preferably of from 2 to 6, more preferably of from 2 to 4, more preferably of from 2.5 to 3.5, most preferably of from 2.7 to 10 3.3. Further, the hydroxyl number of the polyether alcohol may vary within wide ranges and may be of from 5 to 500 mg KOH/g. In particular, the polyether alcohol may have a hydroxyl number of greater than 115 mg KOH/g, suitably greater than 15 120 mg KOH/g. The hydroxyl number of the polyether alcohol may be at least 120 mg KOH/g or at least 130 mg KOH/g or at least 140 mg KOH/g or at least 160 mg KOH/g or at least 180 mg KOH/g or at least 200 mg KOH/g or at least 220 mg KOH/g. Further, the hydroxyl number of the polyether alcohol may be 20 at most 500 mg KOH/g or at most 450 mg KOH/g or at most 400 mg KOH/g or at most 350 mg KOH/g or at most 300 mg KOH/g or at most 280 mg KOH/g. In the present invention, the polyether alcohol to be treated may have a number average molecular weight of at most 25 10,000 g/mol, suitably of from 200 to 8,000 g/mol, more suitably of from 300 to 7,000 g/mol, most suitably of from 400 to 6,000 g/mol. Said molecular weight is preferably at least 100 g/mol, more preferably at least 200 g/mol, more preferably at least 300 g/mol, more preferably at least 400 30 g/mol, more preferably at least 500 g/mol, more preferably at least 550 g/mol, most preferably at least 600 g/mol. Further, said molecular weight may be at most 10,000 g/mol, preferably at most 8,000 g/mol, more preferably at most 7,000 g/mol, more preferably at most 6,000 more preferably at most 5,000 g/mol, more preferably at most 4,000 g/mol, more preferably at most 3,000 g/mol, more preferably at most 2,000 g/mol, more preferably at most 1,500 g/mol, more preferably 5 at most 1,200 g/mol, more preferably at most 1,000 g/mol, more preferably at most 800 g/mol, most preferably at most 750 g/mol. In the process of the present invention, the liquid polyether alcohol is contacted (treated) with a solid 10 adsorbent which has a volume-average particle size greater than 20 µm. Said contact takes place in an adsorbent bed comprising a powder of the adsorbent. At least part of the polyether alcohol to be treated in the present invention is not contacted with the adsorbent before the polyether alcohol 15 contacts the adsorbent in the adsorbent bed. At least 80 wt.% or at least 85 wt.% or at least 90 wt.% or at least 95 wt.% or at least 97 wt.% or at least 99 wt.% or 100 wt.% of the polyether alcohol to be treated is not contacted with the adsorbent before the polyether alcohol contacts the adsorbent 20 in the adsorbent bed. Advantageously, this may result in a relatively fast treatment. Prior to the present treatment process, the adsorbent bed, which may also be referred to as an “adsorbent cake”, may be made in a vessel by providing the vessel with a dispersion comprising the adsorbent powder and 25 a liquid, which liquid may be a portion of the polyether alcohol to be treated, followed by the settling of the adsorbent bed on the bottom of the vessel, which may be effected by applying a pressure whereby the liquid is forced to leave the vessel through the preferably perforated bottom 30 of the vessel, for example through a filter which is placed on the bottom of the vessel. The adsorbent particles are packed in the bed (or cake) resulting in inter-particles pores (or voids) through which the polyether alcohol may pass through. Said initial is preferably uniform, so that the resulting adsorbent bed contains uniformly distributed adsorbent particles (i.e. a uniformly packed adsorbent bed). Such uniform dispersion may be achieved by 5 first mixing and stirring the liquid and the adsorbent particles. Thus, in the present invention, the adsorbent bed may be applied on a filter. The filter should have a sufficiently large mesh size so that the adsorbent particles substantially cannot pass through the filter. After the 10 polyether alcohol to be treated has passed through the adsorbent bed, the treated polyether alcohol passes through the filter and is thereby separated from the adsorbent. As mentioned above, the volume-average particle size of the adsorbent is greater than 20 µm. By said “volume-average 15 particle size” reference is made to the maximum particle size of 50 vol.% of all adsorbent particles (referred to in below Examples as “Dx (50)”). Said volume-average particle size of the adsorbent is greater than 20 µm and may be greater than 25 µm or greater than 30 µm or greater than 35 µm or greater 20 than 40 µm or greater than 45 µm or greater than 50 µm or greater than 75 µm or greater than 100 µm or greater than 125 µm. Further, said volume-average particle size of the adsorbent may be at most 300 µm or at most 250 µm or at most 200 µm or at most 150 µm or at most 100 µm or at most 50 µm 25 or at most 40 µm. Further, the maximum particle size of 10 vol.% of all adsorbent particles (referred to in below Examples as “Dx (10)”) may be of from 5 to 75 µm or 8 to 50 µm or 10 to 35 µm. Still further, the maximum particle size of 90 vol.% of 30 all adsorbent particles (referred to in below Examples as “Dx (90)”) may be of from 50 to 500 µm or 60 to 400 µm or 70 to 350 µm. Furthermore, suitable for use in the present process have a pore volume of at least 0.001 cm³/g or at least 0.01 cm³/g or at least 0.1 cm³/g or at least 0.5 cm³/g, and at most 10 cm³/g or at most 5 cm³/g or at most 3 cm³/g or at most 1.5 cm³/g or at most 1 cm³/g. Said “pore volume” is the total volume of pores in a bed of adsorbent particles. Still further, suitable adsorbents for use in the present process have a bulk density of at least 50 g/l or at least 100 g/l or at least 150 g/l, and at most 1500 g/l or at most 1300 g/l or at most 1200 g/l. Said “bulk density” is the total mass of the adsorbent particles divided by the total volume they occupy. The specific surface area of the adsorbent may be in the range of from 1 to 3000 m²/g, preferably 50 to 2000 m²/g, more preferably 100 to 1000 m²/g. Said specific surface area may be at least 1 m²/g or at least 10 m²/g or at least 50 m²/g. Further, it may be at most 3000 m²/g or at most 1000 m²/g or at most 500 m²/g. In the present invention, the amount of adsorbent with which the polyether alcohol is contacted may be at least 0.05 part by weight (pbw) based on 100 parts by weight of the polyether alcohol to be treated with the adsorbent. Suitably, said amount of adsorbent may be of from 0.05 to 5 pbw, more suitably 0.1 to 3 pbw, even more suitably 0.2 to 2 pbw, most suitably 0.3 to 1 pbw. Further, in the present invention, the polyether alcohol may be contacted with the adsorbent bed for a period of time of from 5 to 120 minutes, preferably 30 to 90 minutes and most preferably 45 to 75 minutes. Further, the treatment (contacting) in the present process may be effected at a temperature of from 10 to 100 °C, preferably 30 to 90 °C and most preferably 40 to 80 °C. Adsorbents which may be used in the present process are not limited to the specific materials listed in the present specification. In general, any material characterized by having above-described particle size, from 5 natural origin or synthetic, from a mineral or an organic source, with a treated or untreated surface, polar or non- polar, and in any form may be used in this invention. Preferably, the adsorbent is inert, meaning that it substantially does not react with the polyether alcohol to be 10 treated. In the present invention, the adsorbent may be selected from at least one of activated carbon, diatomaceous earth, charcoal, attapulgite, and clay. It is to be appreciated that the adsorbent may also be a natural silicate and/or a 15 synthetic silicate. Useful activated carbons or charcoals include those obtained from lignite, gas black, coconut, bagasse, wood, sawdust, peat, pulp-mill waste, blood, bone, etc. Specific activated carbons include Calgon Corporation granular carbons, NORIT granular activated carbons, products 20 of Central Scientific Company, Nuchar activated carbons, products of West Virginia Pulp and Paper Company, and products of Darco Division, ICI Americas, Inc. Illustrative commercially available activated carbons include Type CAL granular carbon (Calgon Corporation) and NORIT R 0.8 granular 25 activated carbon (NORIT Corporation). Attapulgite adsorbents employable in the treatment process of the present invention are available from Engelhard Minerals and Chemicals Corporation. Further, the grades 100/UP Mesh RVM and 200/UP Mesh RVM from Attapulgus Clay may 30 suitably be used. Another suitable adsorbent is diatomaceous earth, which is known to those skilled in the art to be formed from a sedimentary rock of marine or lacustrine deposition, and which consists mainly of shells or frustules of hydrous silica secreted by diatoms (microscopic, one-celled, flowerless plants of the class Bacillarieae). However, in chemical terms, diatomaceous earth is primarily formed of 5 silicon dioxide, albeit in a different physical structure than typically encountered. Impurities typically include other aquatic fossils, sand, clay, volcanic ash, calcium carbonate, magnesium carbonate and silicates, soluble salts and organic matter, while a typical spectrographic analysis 10 on a dry basis may show SiO2, CaO, MgO, Al2O3, Fe2O3, Na2O, V₂O₅, and TiO₂. In physical terms, most diatomaceous earths are powders, having mean particle diameters ranging from 20 to 0.75 micrometers, although aggregates can be obtained having 1.27 centimeter diameters down to fine powders. One 15 example of a freshwater-origin diatomaceous earth is sold commercially as "ODW" grade diatomaceous earth (Oil-Dri Corporation of America). In the above treatment process, the adsorbent is preferably selected from the group consisting of amorphous 20 silicate (e.g. perlite), synthetic silicate, synthetic alumina/magnesia, synthetic hydrotalcite, treated cellulose fibres, untreated cellulose fibres and a combination thereof. Said synthetic silicate may comprise synthetic aluminum silicate and/or synthetic magnesium silicate. More 25 preferably, the adsorbent is selected from the group consisting of amorphous silicate (e.g. perlite), treated cellulose fibres, untreated cellulose fibres and a combination thereof. In specific, the adsorbent may comprise untreated cellulose fibres and/or treated cellulose fibres. 30 Said treated cellulose fibres may be silica-treated (i.e. silicified) cellulose fibres. Further, in specific, the adsorbent may comprise amorphous silicate (e.g. perlite). As a final step in the process, after contacting, the treated polyether alcohol is separated from the adsorbent. This may be done in any way. Preferably, a filtering method is applied to separate the polyether alcohol 5 from the adsorbent, as described above. This may be effected by passing the polyether alcohol through a filter. The (solid) adsorbent then remains behind on the filter. The filter method employed may be selected from any commercially available filtering technology, such as a Funda Type pressure 10 filter from Steri Technologies, Inc. Any number of filtering techniques and methods are acceptable, including but not limited to a primary filtering operation followed by a finish filtering stage to remove extremely fine particles. Preferably, the filtering of the treated polyether 15 alcohol through a filter (filter medium) is conducted under a pressure of 0.7 to 4.0 bar, preferably 1.8 to 3.4 bar. The pressure may be varied (increased) over time, so as to maintain a constant flux of the to be treated polyether alcohol through the adsorbent bed. 20 Further, the present invention relates to a polyether alcohol obtainable by the above-mentioned treatment process. The present invention also relates to a process for preparing a polyurethane foam comprising reacting a polyether alcohol and a polyisocyanate in the presence of a blowing 25 agent, wherein the polyether alcohol is a polyether alcohol obtained or obtainable by the above-mentioned treatment process. In the above-mentioned process for preparing a polyurethane foam, the polyether alcohol is reacted with a 30 polyisocyanate in the presence of a blowing agent. The polyisocyanate may comprise an aromatic polyisocyanate or an aliphatic polyisocyanate, preferably an aromatic polyisocyanate. The aromatic may for example comprise tolylene diisocyanate (TDI) or polymeric TDI, xylylene diisocyanate, tetramethylxylylene diisocyanate, methylene diphenyl diisocyanate (MDI) or polymeric MDI (i.e. 5 polymethylene polyphenyl isocyanate), or a modified product thereof. Preferably, the aromatic polyisocyanate comprises tolylene diisocyanate (TDI), i.e. non-polymeric TDI. The TDI may be a mixture of 80 wt.% of 2,4-TDI and 20 wt.% of 2,6- TDI, which mixture is sold as “TDI-80”. 10 Further, the aliphatic polyisocyanate may for example comprise hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, lysine diisocyanate or isophorone diisocyanate, or a modified product thereof. Further, the polyisocyanate may comprise any mixture of 15 two or more of the polyisocyanates mentioned above. For example, the polyisocyanate may comprise a mixture of TDI and MDI, in particular a mixture wherein the weight ratio of TDI:MDI varies from 10:90 to 90:10. The blowing agent may comprise a chemical blowing agent 20 and/or a physical (non-chemical) blowing agent. Within the present specification, by “chemical blowing agent” reference is made to a blowing agent that may only provide a blowing effect after it has chemically reacted with another compound. In case the blowing agent comprises a chemical blowing agent, 25 said chemical blowing agent preferably comprises water. Water reacts with isocyanate groups of the polyisocyanate, thereby releasing carbon dioxide which causes the blowing to occur. However, other suitable blowing agents, such as for example, acetone, gaseous or liquid carbon dioxide, 30 halogenated hydrocarbons, aliphatic alkanes and alicyclic alkanes may be employed additionally or alternatively. Due to the ozone depleting effect of fully chlorinated, fluorinated alkanes (CFC’s) the use of this type of blowing agent is generally not although it is possible to use them. Halogenated alkanes, wherein at least one hydrogen atom has not been substituted by a halogen atom (including the so-called HCFC’s) have no or less ozone depleting effect 5 and therefore are the preferred halogenated hydrocarbons to be used in physically blown foams. One suitable HCFC type blowing agent is 1-chloro-l,1-difluoroethane. Another suitable halogenated alkane of this type for use as a blowing agent, is methylene chloride (dichloromethane). 10 The above blowing agents may be used singly or in mixtures of two or more. The amount of the blowing agent(s) is determined by the desired density of the polyurethane foam to be prepared. For example, a relatively low density can be obtained by using a 15 relatively high amount of the blowing agent(s), and vice versa. A skilled person can readily determine the amount of blowing agent (physical and/or chemical blowing agent) needed to obtain a desired foam density. Water may be used as a blowing agent in an amount which 20 is at least 0.1 part per hundred parts by weight of polyether alcohol (pphp) or at least 0.5 pphp or at least 1 pphp. Further, water may be used as a blowing agent in an amount which is at most 10 parts per hundred parts by weight of polyether alcohol (pphp) or at most 5 pphp or at most 3 pphp 25 or at most 2 pphp. In case of halogenated hydrocarbons, aliphatic alkanes and alicyclic alkanes, the amount of the blowing agent may be of from 1 to 50 parts per hundred parts by weight of polyether alcohol (pphp), suitably of from 1 to 30 pphp, more 30 suitably of from 1 to 20 pphp. Further, preferably, the polyurethane foam which may be prepared is a flexible polyurethane foam. Further, said flexible polyurethane foam is suitably a slabstock foam. Within the present by “slabstock foam” reference is made to a foam that is made by applying a free rise (unconstrained rise) of the foam. The isocyanate index (or NCO index) may vary within wide 5 ranges and may be of from 60 to 120. In particular, the isocyanate index may be at most 120, more suitably at most 110, more suitably at most 100, most suitably at most 90. Further, the isocyanate index is preferably higher than 60 and may be at least 70 or at least 80 or at least 90. 10 Within the present specification, “isocyanate index” is calculated as 100 times the mole ratio of —NCO groups (isocyanate groups) to NCO—reactive groups in the reaction mixture. In other words, the isocyanate index is defined as: [(actual amount of isocyanate)/(theoretical amount of 15 isocyanate)]*100, wherein the “theoretical amount of isocyanate” equals 1 equivalent isocyanate (NCO) group per 1 equivalent isocyanate-reactive group. Such “isocyanate-reactive groups” as referred to above include for example OH groups from the polyether alcohol and 20 from any water that may be used as a blowing agent. Isocyanate groups also react with water. Additionally, other components may also be present during the above-mentioned polyurethane foam preparation process, such as one or more polyurethane catalysts, surfactants 25 and/or cross-linking agents. Polyurethane catalysts are known in the art and include many different compounds. Suitable catalysts include tin-, lead- or titanium-based catalysts, preferably tin-based catalysts, such as tin salts and dialkyl tin salts of 30 carboxylic acids. Specific examples are stannous octoate, stannous oleate, dibutyltin dilaureate, dibutyltin acetate and dibutyltin diacetate. Other suitable catalysts are tertiary amines, such as, for instance, bis(2,2'- dimethylamino)ethyl ether, triethylamine, triethylenediamine and dimethylethanolamine (DMEA). Examples of commercially available tertiary amine catalysts are those sold under the tradenames Niax, Tegoamin and Dabco (all 5 trademarks). The catalyst is typically used in an amount of from 0.01 to 2.0 parts by weight per hundred parts by weight of polyether alcohol (php). Preferred amounts of catalyst are from 0.05 to 1.0 php. The use of foam stabilisers (surfactants) is well known. 10 Organosilicone surfactants are most conventionally applied as foam stabilisers in polyurethane production. A large variety of such organosilicone surfactants is commercially available. Usually, such foam stabiliser is used in an amount of from 0.01 to 5.0 parts by weight per hundred parts by weight of 15 polyether alcohol (pphp). Preferred amounts of stabiliser are from 0.25 to 2.0 pphp, more preferably of from 0.75 to 1.5 pphp. The use of cross-linking agents in the production of polyurethane foams is also well known. Polyfunctional glycol 20 amines are known to be useful for this purpose. The polyfunctional glycol amine which is most frequently used and is also useful in the preparation of polyurethane foams, especially flexible polyurethane foams, is diethanolamine, often abbreviated as DEOA. A cross-linking agent may be 25 applied in amounts up to 2 parts by weight per hundred parts by weight of polyether alcohol (pphp), but amounts in the range of from 0.01 to 0.5 pphp are most suitably applied. In addition, other well-known auxiliaries, such as colorants, flame retardants and fillers, may also be used 30 during the above-mentioned polyurethane foam preparation process. Said polyurethane foam preparation process may involve combining the polyisocyanate, the polyether alcohol, the blowing agent, a catalyst and surfactant, crosslinker, flame retardant, colorant and/or filler, in any suitable manner to obtain the polyurethane foam. For example, said process may comprise mixing the polyether alcohol, the 5 blowing agent, a catalyst and any other optional component(s) except the polyisocyanate, and then adding the polyisocyanate. Further, the above-mentioned polyurethane foam preparation process may comprise forming the foam into a 10 shaped article before it fully sets. Suitably, forming the foam may comprise pouring the liquid mixture containing all components into a mould before gelling is complete. Further, the present invention relates to a polyurethane foam obtainable by the above-mentioned process for preparing 15 a polyurethane foam, and to a shaped article comprising a polyurethane foam obtained or obtainable by said process. The invention is further illustrated by the following Examples. Examples 20 1. Experimental procedure Materials (polyether alcohols, adsorbents, polyisocyanate and other components) used in the polyether alcohol treatment experiments and subsequent polyurethane foam experiments are described in Table 1. Regarding the particle size for the 25 adsorbents, “Dx (10)”, “Dx (50)” and “Dx (90)” refer to the maximum particle sizes of 10, 50 and 90 vol.%, respectively, of all adsorbent particles. Table 1 POLYETHER ALCOHOLS Polyol A Polyether polyol made by ring-opening polymerization of propylene oxide in the presence of DMC catalyst and glycerol: MW = 673 g/mol; = 250 mg KOH/g; PO content = 100 wt.%; PHC = 0%; DMC catalyst amount = 120-150 ppmw Polyol B Dispersion of 45 wt.% of solid styrene- acrylonitrile (SAN) polymer particles in Polyol A (base polyol). ADSORBENTS Adsorbent 1 Filtracel-ESG-950, commercially available from J. Rettenmaier & Sohne: made of silica-treated (silicified) cellulose fibers; particle size: Dx (10) = 29.8 µm; Dx (50) = 133.2 µm; Dx (90) = 345.7 µm; bulk density = 170-290 g/l; B.E.T. surface area (N2; 20 °C) = 28-34 m²/g; water retention [Westinghouse] = 616% Adsorbent 2 Arbocel-BWW-40-C, commercially available from J. Rettenmaier & Sohne: made of granulated cellulose fibers; particle size: Dx (10) = 15.1 µm; Dx (50) = 47.9 µm; Dx (90) = 139.8 µm; bulk density = 332 g/l; B.E.T. surface area (N₂; 20 °C) = 2.3-2.7 m²/g; water retention [Westinghouse] = 439% Adsorbent 3 Dicalite 478, commercially available from Dicalite Europe: made of amorphous silicate [perlite]; dry powder; particle size: Dx (10) = 11.1 µm; Dx (50) = 31.3 µm; Dx (90) = 76.7 µm; cake density (wet) = 12.5-15.2 lbs/ft³ (200-243 g/l); bulk density = 900- 1100 g/l; pore volume = 0.5-1.5 cm³/g POLYISOCYANATE TDI-80 80:20 (by weight) blend of 2,4- and 2,6- isomers of TDI (tolylene diisocyanate) commercially from Mitsui; free NCO content = 48.3% OTHER COMPONENTS Niax A1 Amine based catalyst available from Momentive Performance Materials Dabco 33LV 33 wt.% solution of triethylene diamine in dipropylene glycol, commercially available from Air Products and Chemicals Tegostab B8002 Silicone based surfactant commercially available from Momentive Performance Materials DMC = double metal cyanide; PO = propylene oxide; MW = molecular weight; PHC = primary hydroxyl content The experimental setup used in the polyether alcohol 5 treatment experiments was a Nutsche filtration setup, comprising an electrically heated cylindrical vessel (volume: 12 liters) at the bottom of which a stainless steel, perforated plate was provided on which a filter medium was supported. First a portion (i.e. 4 wt.%) of the polyether 10 alcohol to be treated and the adsorbent were mixed together for 30 minutes to obtain a uniform dispersion. Then the dispersion comprising the polyether alcohol and the adsorbent was charged to the pressure filter vessel from the top via a feed charging port. 15 The filter medium comprised (i) a filter pad (Beer Filter Pad, grade: XE1200H) having a surface area of 0.015 m² and a diameter of 14.0 cm, on top of which (ii) a filter cloth (supplied by Filtration Group B.V.; grade: 32-10.301) having a filtration surface area of 0.011 m² and a diameter of 11.9 20 cm was provided, thereby forming a gasket of 10.5 mm made of filter pad (i) and fully surrounding filter cloth (ii). Filtration was achieved by application of pressure with nitrogen. A constant nitrogen was maintained in the filter by means of a forward pressure regulator. The pressure was varied from 1.8 to 3.4 barg by said forward pressure regulator, so as to maintain a constant flux. On top of the 5 filter, a cake (bed) made of the adsorbent was formed from the above-mentioned charged dispersion, which cake the polyether alcohol passed through under the influence of the nitrogen pressure. The remaining polyether alcohol to be treated was charged to the vessel and passed through the 10 cake. The filtrate comprising treated polyether alcohol was collected into a filtrate collection can which was placed under the filter on a weighing balance. In the subsequent polyurethane foam experiments, the non- polyisocyanate components shown in Table 2, including the 15 treated polyether alcohol (i.e. treated Polyol A, including treated Polyol A (base polyol) in Polyol B), were mixed in a high-speed mixer at about 2,500 rpm for 50 seconds. Then the polyisocyanate component was added and the mixture was stirred for around 5 seconds and then poured into a box of 20 dimensions of 30 cm * 20 cm * 15 cm to form a polyurethane foam. The full rise time (FRT) was measured. The full rise time was the time period between the time of adding the polyisocyanate and the time at which a maximum height was achieved. 25

2 Foam formulation (pbw = parts by weight) Polyol A (pbw) 50 Polyol B (pbw) 50 Water (pbw) 2 Diethanolamine (pbw) 0.06 Niax A1 (pbw) 0.15 Dabco 33LV (pbw) 0.3 Tegostab B8002 (pbw) 1.68 TDI-80 (isocyanate index) 84 2. Polyether alcohol treatment experiments and polyurethane foam experiments 5 In Table 3, the polyether alcohol, the adsorbent (type and amount), the treatment temperature and the (constant) flux for the polyether alcohol treatment experiments are shown. The flux is defined as the amount of polyether alcohol passing through a cake surface area of 1 m² per hour. The 10 amount of adsorbent is based on the total amount of polyether alcohol to be treated. Table 4 shows the appearance and stability of the thus treated polyether alcohol. The appearance was observed visually at the end of the time period shown under 15 “Stability”. Further, said stability is herein defined as the number of weeks, either after preparation (comparison) or after treatment (invention) of the polyether alcohol, within which time period no phase separation was observed. Further, Table 4 shows the foam full rise time (foam FRT) 20 in the polyurethane foam experiments wherein polyurethane foams were prepared from the treated polyether alcohol and the polyisocyanate. 3 Exp. Polyether Adsorbent: Temp. Flux alcohol type & amount (wt.%) (°C) (kg/h/m²) 1^(*) Polyol A None - - - 2 Polyol A Adsorbent 3 1.0 70 96 3 Polyol A Adsorbent 3 0.5 50 113 4 Polyol A Adsorbent 3 0.8 70 140 5 Polyol A Adsorbent 3 0.4 70 120 6 Polyol A Adsorbent 3 0.3 50 120 7 Polyol A Adsorbent 3 1.0 70 180 8 Polyol A Adsorbent 2 1.0 70 90 9 Polyol A Adsorbent 1 1.0 70 90 (*) = Not according to the invention. Table 4 Exp. Appearance Stability (weeks) FRT (sec.) 1^(*) Pink & 2 phases 1 120 2 Clear & colorless 12 132 3 Clear & colorless 12 132 4 Clear & colorless 12 132 5 Clear & colorless 12 132 6 Clear & colorless 12 132 7 Clear & colorless 12 132 8 Clear & colorless 12 132 9 Clear & colorless 12 132 5 (*) = Not according to the invention. With reference to Tables 3 and 4, it has been demonstrated that by treatment of a polyether alcohol, that was prepared using a composite metal cyanide complex catalyst 10 (DMC catalyst) and that still contained DMC catalyst, with an adsorbent in accordance with the present invention, a different, treated polyether alcohol is obtained in that, surprisingly, the treated alcohol has an increased long-term stability, as evidenced by the absence of any phase separation during 12 weeks of storage in Experiments 2-9 whereas the untreated polyether alcohol showed 2 separate 5 phases already after 1 week, one of which 2 phases (layers) was pink. In addition, advantageously, treatment in accordance with the present invention resulted in a treated polyether alcohol which was no longer pink but clear and colourless, which is 10 advantageous in some applications where a pink colour is undesired. Further, it has been demonstrated that treatment in accordance with the present invention surprisingly resulted in a treated polyether alcohol which resulted in a longer 15 foam full rise time (foam FRT) when reacted with polyisocyanate to produce a polyurethane foam, than the untreated polyether alcohol. A relatively long FRT is advantageous for reasons as discussed in the above “Background of the invention” section.

Claims

C L A M S 1. A process for treatment of a polyether alcohol, comprising: providing a polyether alcohol prepared using a composite metal cyanide complex catalyst; 5 contacting the polyether alcohol with an adsorbent, the adsorbent having a volume-average particle size greater than 20 µm, in an adsorbent bed comprising a powder of the adsorbent, wherein at least part of the polyether alcohol is not contacted with the adsorbent before the polyether alcohol 10 contacts the adsorbent in the adsorbent bed; and separating the polyether alcohol from the adsorbent. 2. The process according to claim 1, wherein the adsorbent bed is applied on a filter, through which filter the treated 15 polyether alcohol is passed and is separated from the adsorbent. 3. The process according to claim 1 or 2, wherein the maximum particle size of 10 vol.% of all adsorbent particles is of from 5 to 75 µm. 4. The process according to any one of claims 1 to 3, 20 wherein the maximum particle size of 90 vol.% of all adsorbent particles is of from 50 to 500 µm 5. The process according to any one of claims 1 to 4, wherein the adsorbent is selected from the group consisting of amorphous silicate, synthetic silicate, synthetic alumina/magnesia, synthetic hydrotalcite, treated cellulose fibres, untreated cellulose fibres and a combination thereof. 6. The process according to one of claims 1 to 5, wherein the polyether alcohol to be treated contains a composite metal cyanide complex catalyst in an amount of from 1 to 200 parts per million by weight (ppmw). 7. A polyether alcohol obtainable by the process according to any one of claims 1-6. 8. A process for preparing a polyurethane foam comprising 5 reacting a polyether alcohol and a polyisocyanate in the presence of a blowing agent, wherein the polyether alcohol is a polyether alcohol obtained by the process according to any one of claims 1-6 or the polyether alcohol according to claim 7. 10 9. A polyurethane foam obtainable by the process according to claim 8. 10. A shaped article comprising a polyurethane foam obtained by the process according to claim 8 or the polyurethane foam according to claim 9.