Batch process for preparation of polyether alcohols using double metal cyanide catalysts

Abstract

The invention relates to a batch process for producing polyetherols P having a hydroxyl number greater than 115 mg KOH / g by reacting a starter compound S1 and a starter compound S2 with one or more alkylene oxides in the presence of a composite metal cyanide complex catalyst, the batch process comprises: a) forming a starter mixture comprising a starter compound S1 and a catalyst and activating the catalyst by adding an alkylene oxide, followed by b) continuously adding an alkylene oxide; and c) continuously adding an initiator compound S2; wherein no alkylene oxide is added between step a) and step b), and the continuous addition of alkylene oxide in step b) is not interrupted before the total weight of alkylene oxide required for the production of polyether alcohol P has been added; step c) is stopped before step b) is stopped, and step c) is stopped once less than 80% of the total weight of the alkylene oxides required to produce the polyetherol P is added in step b).

Description

TECHNICAL FIELD

[0001] The present invention relates to a process for the preparation of a polyether alcohol, a polyether alcohol obtainable by the process, a process for the preparation of a polyurethane foam using the polyether alcohol, a polyurethane foam obtainable by the process and a shaped article comprising the polyurethane foam. BACKGROUND

[0002] Polyether alcohols, such as polyether polyols, are commonly used in the manufacture of polyurethane foams, such as flexible polyurethane foams, which have found widespread use in a variety of industrial and consumer applications. Polyether alcohols are also commonly referred to as polyoxyalkylene alcohols. Polyether alcohols are typically obtained by reacting a starter compound or initiator having one active hydrogen atom or multiple 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 include complex metal cyanide complex catalysts, which are also commonly referred to as double metal cyanide (DMC) catalysts.

[0003] An advantage associated with the DMC catalyzed production of polyether alcohols is that it is faster and more efficient than traditional methods that use potassium hydroxide (KOH) as a catalyst. Further, the DMC catalyzed process is more environmentally friendly and has a reduced carbon (C02) footprint. When the DMC catalyzed process is run as a batch process, the DMC catalyst is first activated. It is known that at the beginning of the batch process, a small amount of alkylene oxide, for example propylene oxide, is combined with a reactive compound, such as some polyether alcohol from a previous batch, in the presence of the DMC catalyst. After a period of time, the DMC catalyst is activated, as indicated by a drop in alkylene oxide pressure. Then at some point after activation, more alkylene oxide and initiator can be continuously added to make the desired polyether alcohol.

[0004] WO201703748 discloses a process for the preparation of a polyether polyol product comprising: a) activating a DMC catalyst complex in the presence of i) an alkoxylated starter and ii) up to 10 wt% of 1,2-propylene oxide based on the weight of the alkoxylated starter, the hydroxyl equivalent weight of the alkoxylated starter being from 50% to 100% of the hydroxyl equivalent weight of the polyether polyol product; b) continuously feeding an alkylene oxide containing at least 50 wt% 1,2-propylene oxide to the activated DMC catalyst under polymerization conditions, wherein from the start of step b) a low equivalent weight starter is continuously fed to the activated DMC catalyst under polymerization conditions, the feeding of the low molecular weight starter is continued until 80% to 95% of the alkylene oxide feed in step b) is complete and then the feeding of the low molecular weight starter is stopped while the alkylene oxide feed is continued, wherein the total weight of the low molecular weight starter added in step b) is from 0.2% to 25% of the total weight of the alkylene oxide added in step b).

[0005] It is an object of the present invention to provide a batch polyether alcohol production process comprising a separate initial DMC catalyst activation step, wherein the final polyether alcohol product has a relatively low polydispersity and viscosity, which can be evidenced by a relatively small fraction of high molecular weight polyether alcohol. A relatively low polydispersity indicates a relatively narrow molecular weight distribution. SUMMARY

[0006] It has surprisingly been found that the above object can be achieved by a batch polyether alcohol production process, wherein a polyether alcohol having a hydroxyl number of more than 115 mg KOH / g is prepared by reacting one or more starter compounds with one or more alkylene oxides in the presence of a complex metal cyanide complex catalyst (double metal cyanide (DMC) catalyst), and wherein the alkylene oxide and the starter compound are continuously added, characterized in that the continuous addition of the starter compound is stopped as soon as less than 80% of the total weight of alkylene oxide required for the preparation of the polyether alcohol has been continuously added.

[0007] The present invention thus relates to a batch process for preparing a polyether alcohol P having a hydroxyl number of more than 115 mg KOH / g by reacting a starter compound S1 and a starter compound S2 with one or more alkylene oxides in the presence of a complex metal cyanide complex catalyst, the starter compound having one active hydrogen atom or a plurality of active hydrogen atoms, the batch process comprising:

[0008] a) forming a starter mixture comprising the starter compound S1 and the catalyst and activating the catalyst by adding alkylene oxide, followed by

[0009] b) continuously adding alkylene oxide; and

[0010] c) continuously adding the starter compound S2;

[0011] wherein

[0012] the starter compound S1 has (I) a nominal functionality equal to the nominal functionality of the polyether alcohol P and a hydroxyl number within 10% of the hydroxyl number of the polyether alcohol P and / or (II) an equivalent weight of 10 g / mol to 10,000 g / mol;

[0013] the starter compound S2 has an equivalent weight of 10 g / mol to 300 g / mol;

[0014] no alkylene oxide is added between step a) and step b), and the continuous addition of alkylene oxide in step b) is not interrupted before the total weight of alkylene oxide required for the preparation of the polyether alcohol P has been added;

[0015] Step c) is stopped before step b) is stopped and step c) is stopped once less than 80% of the total weight of alkylene oxide required for the preparation of the polyether alcohol P has been added in step b).

[0016] Furthermore, the present application relates to a polyether alcohol obtainable by the above-mentioned process.

[0017] The present application also relates to a process for the preparation of a polyurethane foam, comprising reacting a polyether alcohol with 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.

[0018] Furthermore, the present application relates to a polyurethane foam obtainable by the above-mentioned process for the preparation of a polyurethane foam, and to a shaped article comprising a polyurethane foam obtained or obtainable by the process. DETAILED DESCRIPTION

[0019] While the processes and compositions of the present application can be described in terms of“comprising,”“containing,” or“including” one or more of the various steps or components described, they also can“consist essentially of” or“consist of” one or more of the various steps or components described.

[0020] In the context of the present application, in case the composition comprises two or more components, these components are selected in a total amount of not more than 100 wt.-%.

[0021] Where upper and lower limits are referenced for a property, ranges of values defined by the combination of any of the upper limits with any of the lower limits are also implied.

[0022] The term“molecular weight” (or“MW”) is used herein to refer to the number average molecular weight, unless otherwise indicated or required by context. The number average molecular weight of a polyether alcohol can be measured by gel permeation chromatography (GPC) or vapor pressure osmometry (VPO).

[0023] The term“hydroxyl (OH) number” or“OH number” as used herein refers to the number of milligrams of potassium hydroxide that corresponds to the hydroxyl content in one gram of polyether alcohol as determined by wet titration. Thus, the OH number or value is expressed in mg KOH / g. The hydroxyl number can be determined according to ASTM D4274.

[0024] The term“equivalent weight” (or“EW”) as used herein refers to the weight of a polyether alcohol per reaction site. The equivalent weight is 56,100 divided by the hydroxyl number of the polyether alcohol.

[0025] The term "functionality" or "hydroxyl (OH) functionality" of a polyether alcohol refers to the number of hydroxyl groups per molecule of the polyether alcohol. The nominal functionality of a polyether alcohol is the same as the nominal functionality of its starter compound (initiator). Unless otherwise specified, the functionality refers to the actual average functionality, which can be lower than the nominal functionality, and is determined by dividing the number average molecular weight of the polyether alcohol by the equivalent weight of the polyether alcohol.

[0026] The term "primary hydroxyl content" (or "PHC") as used herein refers to the relative proportion (in %) of primary hydroxyl groups in a polyether alcohol based on the total number of hydroxyl groups including primary and secondary hydroxyl groups. The primary hydroxyl content can be determined according to ASTM D4273.

[0027] The terms "ethylene oxide content" and "propylene oxide content" in connection with a polyether alcohol refer to those moieties in the polyether alcohol which are derived from ethylene oxide and propylene oxide, respectively. The contents can also be referred to as ethylene oxide content and propylene oxide content, respectively. Further, the contents are herein based on the total alkylene oxide weight. The ethylene oxide content can be determined according to ASTM D4875.

[0028] The process of the present application is a batch process. In a batch process, the desired product in the present application, the polyether alcohol P, is not continuously produced in a reactor, but is produced in a reactor during a certain period of time, after which at least a part of the product is recovered, after which a new batch can be started.

[0029] In the present application, the polyether alcohol P has a hydroxyl number of greater than 115 mg KOH / g, suitably greater than 120 mg KOH / g. The hydroxyl number of the polyether alcohol P can 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 P can be 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.

[0030] Further, in the present application, the polyether alcohol P contains ether linkages (or ether units). Further, the polyether alcohol can additionally contain ester linkages (or ester units) and / or carbonate linkages (or carbonate units). Preferably, the polyether alcohol does not contain ester linkages (or ester units). Further, preferably, the polyether alcohol does not contain carbonate linkages (or carbonate units). Still further, the polyether alcohol can consist of ether linkages.

[0031] Further, in the present application, the polyether alcohol P contains one or more hydroxyl groups. Thus, the polyether alcohol P can be a polyether mono-alcohol or a polyether polyol. A mono-alcohol is an alcohol containing one hydroxyl group, while a polyol is an alcohol containing two or more hydroxyl groups.

[0032] In step a) of the present process, a starter mixture comprising the starter compound S1 and the complex metal cyanide complex catalyst is formed. Step a) is carried out before steps b) and c) are performed. Preferably, in step a), the starter mixture is formed in the reactor. Alternatively, the starter mixture can be formed outside the reactor, after which the thus obtained starter mixture is charged to the reactor.

[0033] Thus, in the process of the present application, a complex metal cyanide complex catalyst is used. Complex metal cyanide complex catalysts are also commonly referred to as double metal cyanide (DMC) catalysts. Complex metal cyanide complex catalysts are generally represented by the following formula (1):

[0034] (1) M 1 a [M 2 b (CN) c ] d .e(M 1 f X g ).h(H20).i(R)

[0035] wherein M 1 and M 2 are each 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 that can vary depending on the atomic balance of the metal, the number of organic ligands to be coordinated, etc.

[0036] In the above formula (1), M 1 is preferably a metal selected from Zn(II) or Fe(II). In the above formula, M 2 is preferably a metal selected from Co(III) or Fe(III). However, other metals and oxidation states can also be used, as known in the art.

[0037] 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 organic ligand can be used. Specifically, one or more compounds selected from the group consisting of t-butanol, n-butanol, isobutanol, t-amyl alcohol, isoamyl alcohol, N,N-dimethylacetamide, glycol dimethyl ether (ethylene glycol dimethyl ether), diethylene glycol dimethyl ether (diethylene glycol dimethyl ether), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), ethylene glycol mono-t-butyl ether, isopropyl alcohol, and dioxane can be used as the organic ligand. The dioxane can 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 complex metal cyanide complex catalyst is t-butanol. Furthermore, as the alcohol organic ligand, a polyol, preferably a polyether polyol, can be used. More preferably, a poly(propylene glycol) having a number average molecular weight in the range of 500 to 2,500 Dalton, preferably 800 to 2,200 Dalton, can be used as the organic ligand or one of the organic ligands. Most preferably, such a poly(propylene glycol) is used in combination with t-butanol as the organic ligand. The complex metal cyanide complex catalyst can be manufactured by a publicly known manufacturing method.

[0038] In the present application, the starter compound S1 satisfies one or both of the following two requirements (I) and (II):

[0039] (I) the starter compound S1 has a nominal functionality equal to the nominal functionality of the polyether alcohol P and a hydroxyl value within 10% of the hydroxyl value of the polyether alcohol P, and / or

[0040] (II) the starter compound S1 has an equivalent weight of 10 g / mol to 10,000 g / mol.

[0041] Thus, in the present application, the compound S1 can satisfy only the requirement (I), or can satisfy only the requirement (II), or can satisfy both the requirements (I) and (II).

[0042] Under the requirement (I), the starter compound S1 has a hydroxyl value within 10% of the hydroxyl value of the polyether alcohol P. This means that under the requirement (I), the hydroxyl value of the starter compound S1 differs from the hydroxyl value of the polyether alcohol P by not more than 10%. Preferably, under the requirement (I), the starter compound S1 has a hydroxyl value within 8%, more preferably within 6%, more preferably within 4%, more preferably within 2%, most preferably within 1% of the hydroxyl value of the polyether alcohol P. In addition, the hydroxyl value of the starter compound S1 can be equal to the hydroxyl value of the polyether alcohol P.

[0043] Requirement (I) is met in cases where a part of the polyetherol P prepared in a previous batch of the process according to the application is used as starting compound S1 in the next batch of the process according to the application. Thus, the starting compound S1 can comprise the same product as the final target product (polyetherol P). Up to 50 wt.-% or up to 40 wt.-% or up to 30 wt.-% or up to 20 wt.-% or up to 10 wt.-% or up to 5 wt.-% of the total weight of the polyetherol P prepared in said previous batch can be used as starting compound S1 in said next batch. A part of said polyetherol P thus prepared can be left in the reactor at the end of the batch process (often also referred to as “bottoms”) and can be used as starting compound S1 in the next batch. It is also possible that said polyetherol P thus prepared is first stored in a separate storage vessel and then a part thereof is sent back to the reactor and used as starting compound S1 in the next batch. The above-mentioned “bottoms” can be subjected to a pre-treatment prior to step a) of the present process, wherein such pre-treatment can for example include stripping with a stripping gas to remove light compounds (such as moisture) and / or refining to remove or neutralize any non-DMC catalyst (such as KOH) used in the previous batch.

[0044] Under requirement (II), the starting compound S1 has an equivalent weight of 10 g / mol to 10,000 g / mol. Under said requirement (II), the starting compound S1 can have an equivalent weight of at least 40 g / mol or at least 45 g / mol or at least 50 g / mol or at least 55 g / mol or at least 65 g / mol or at least 80 g / mol or at least 100 g / mol or at least 120 g / mol or at least 140 g / mol or at least 160 g / mol or at least 180 g / mol or at least 200 g / mol. Furthermore, under said requirement (II), the starting compound S1 can have an equivalent weight of at most 8,000 g / mol or at most 6,000 g / mol or at most 4,000 g / mol or at most 3,000 g / mol or at most 2,700 g / mol or at most 2,400 g / mol or at most 2,200 g / mol or at most 2,000 g / mol or at most 1,500 g / mol or at most 1,000 g / mol or at most 500 g / mol or at most 450 g / mol or at most 400 g / mol or at most 350 g / mol or at most 300 g / mol or at most 280 g / mol or at most 250 g / mol.

[0045] Furthermore, under requirement (II), the starting compound S1 can have a functionality of 1 to 8, preferably 2 to 6, more preferably 2 to 4, more preferably 2.5 to 3.5, most preferably 2.7 to 3.3.

[0046] The case where only requirement (II) is fulfilled and not requirement (I) is the case where in the preceding batch another polyether alcohol (another grade) is prepared, which has a different nominal functionality than the nominal functionality of the desired polyether alcohol P to be prepared in the next batch, and / or has a hydroxyl number which differs by more than 10% from the hydroxyl number of said polyether alcohol P. When such a grade change is made, a portion of the other polyether alcohol prepared in the preceding batch can be used as starting compound S1 in the next batch in which the polyether alcohol P is prepared according to the process of the present application. Thus, the starting compound S1 can comprise a product which is different from the final target product (polyether alcohol P). Up to 50 wt.-% or up to 40 wt.-% or up to 30 wt.-% or up to 20 wt.-% or up to 10 wt.-% or up to 5 wt.-% of the total weight of said other polyether alcohol prepared in said preceding batch can be used as starting compound S1 in said next batch. At the end of the batch process, a portion of said other polyether alcohol thus prepared can remain in the reactor (often also referred to as “bottoms”) and be used as starting compound S1 in the next batch in which the polyether alcohol P is prepared. It is also possible that said other polyether alcohol thus prepared is first stored in a separate storage vessel and then a portion thereof is sent back to the reactor and used as starting compound S1 in the next batch in which the polyether alcohol P is prepared. Prior to step a) of the present process, the above-mentioned “bottoms” can be pre-treated, wherein such pre-treatment may, for example, comprise stripping with a stripping gas to remove light compounds such as moisture and / or refining to remove or neutralize any non-DMC catalyst (such as KOH) used in the preceding batch.

[0047] The amount of starting compound S1 used in step a) of the present process can vary within a wide range, based on the total weight of the final product (polyether alcohol P) in the reactor. The ratio can be from 1 wt.-% to 80 wt.-%, or from 3 wt.-% to 70 wt.-%, or from 5 wt.-% to 60 wt.-%, or from 7 wt.-% to 50 wt.-%, or from 8 wt.-% to 40 wt.-%. The ratio is related to the so-called “build ratio”, which is defined in the present specification as the ratio of the total weight of the final product in the reactor to the weight of the starting compound S1.

[0048] The starter compound S1 can consist of one starter compound fulfilling one or both of the requirements (I) and (II). Alternatively, the starter compound S1 can consist of two or more starter compounds, suitably of a mixture of two starter compounds, each of the starter compounds fulfilling one or both of the requirements (I) and (II). In the latter case, for example, one of the starter compounds can fulfill the requirements (I) and (II), while the other starter compound can fulfill only the requirement (II). Further, additionally, in step a) of the present process one or more starter compounds other than the starter compound S1 can be used to form a starter mixture. Preferably, in the present invention no starter compound is used in step a) which does not fulfill either of the requirements (I) and (II).

[0049] In the present invention, step b) can be started before step c), or step b) and step c) can be started simultaneously, or step c) can be started before step b). Preferably step b) is started before step c). In the present invention, the polyetherol P is prepared in the reactor. However, as mentioned above, step a) can be conducted within the reactor, or alternatively, can be conducted outside the reactor, after which the thus obtained starter mixture is charged to the reactor. Step b) and step c) are conducted within the reactor, which means that in step b) the alkylene oxide is added continuously to the reactor, and in step c) the starter compound S2 is added continuously to the reactor.

[0050] In step a) of the present process, a starter mixture comprising the starter compound S1 and the complex metal cyanide complex catalyst is formed. In step a), the starter compound S1 can be combined with the complex metal cyanide complex catalyst as described above, wherein said catalyst to be combined with the starter compound S1 preferably comprises a fresh complex metal cyanide complex catalyst. In the present specification, a "fresh" catalyst means an unactivated catalyst which has not been used as a catalyst in a chemical process, in particular an unactivated catalyst which has not been exposed to an alkylene oxide. However, a fresh catalyst is suitable for use as a catalyst in a chemical process, which means that it is the final catalyst obtained as a product in a catalyst preparation process, and not any intermediate catalyst or catalyst precursor. In the present specification, a "used" catalyst means a catalyst which has been used as a catalyst in a chemical process, in particular a catalyst which has been exposed to an alkylene oxide.

[0051] The fresh composite metal cyanide complex catalyst preferably used in step a) should be distinguished from any composite metal cyanide complex catalyst that may be present in the starter compound S1 before the starter mixture comprising the starter compound S1 and the composite metal cyanide complex catalyst (preferably comprising fresh composite metal cyanide complex catalyst) is formed in step a). The composite metal cyanide complex catalyst present in the starter compound S1 before step a) may originate from a previous batch in which the composite metal cyanide complex catalyst was also used to prepare polyether alcohols, a portion of which may subsequently be used as the starter compound S1 in a subsequent batch in which polyether alcohol P is prepared according to the process of the present invention. Thus, the starter compound S1 may include used composite metal cyanide complex catalysts. Furthermore, preferably, the starter compound S1 does not contain fresh composite metal cyanide complex catalysts.

[0052] Therefore, in the present invention, the polyether alcohol P is prepared in the presence of a composite metal cyanide complex catalyst, which composite metal cyanide complex catalyst comprises (i) the composite metal cyanide complex catalyst used in step a) to form a starter mixture comprising the starter compound S1 and the catalyst, the catalyst (i) being activated in step a), as discussed further below, and preferably comprising fresh catalyst, and (ii) the composite metal cyanide complex catalyst optionally present in the starter compound S1 before step a), the catalyst (ii) being activated in step a), as discussed further below, and comprising used catalyst.

[0053] In the present invention, the starter compound S2 is added in step c). In the present invention, the polyether alcohol P is prepared in a reactor. Step a) can be carried out partially (i.e., only the catalyst is activated) or completely in the reactor, or alternatively can be carried out partially (i.e., the starter mixture is formed before the catalyst is activated) or completely outside the reactor, after which the starter mixture obtained is charged to the reactor. Steps b) and c) are carried out in the reactor, which means that the alkylene oxide is continuously added to the reactor in step b) and the starter compound S2 is continuously added to the reactor in step c).

[0054] Furthermore, in the present invention, no alkylene oxide is added between step a) and step b). This means that in the present invention, alkylene oxide is added only in step a) and step b). Furthermore, in the present invention, the continuous addition of alkylene oxide in step b) is not interrupted until the total weight of alkylene oxide required for preparing the polyether alcohol P has been added. This means that in the present invention, the continuous addition of alkylene oxide in step b) is not temporarily discontinued, but is only stopped when the total weight of alkylene oxide required for preparing the polyether alcohol P has been added.

[0055] In the present invention, in step a), an alkylene oxide is added to the starter mixture comprising the starter compound S1 and the complex metal cyanide complex catalyst in order to activate the catalyst. A relatively small amount of alkylene oxide can be sufficient to achieve such catalyst activation. The amount of alkylene oxide added in step a) can be from 0.5 wt.-% to 20 wt.-% or from 1 wt.-% to 15 wt.-% or from 2 wt.-% to 10 wt.-%, based on the weight of the starter mixture prior to the addition of the alkylene oxide (i.e. the alkylene oxide added to activate the catalyst). Any alkylene oxide can be added in step a) to achieve such catalyst activation. The alkylene oxide added in step a) can comprise one or more of propylene oxide, ethylene oxide and butylene oxide, preferably propylene oxide and / or butylene oxide, most preferably only propylene oxide. Furthermore, as mentioned above, no alkylene oxide is added between step a) and step b). Still further, (i) the addition of the alkylene oxide in step a) is completed and (ii) the continuous addition of alkylene oxide in step b) is started not immediately after each other. For step b), only after the catalyst has been activated in step a) is started. Such catalyst activation can be evidenced by a drop in the alkylene oxide pressure in the reactor. This pressure drop indicates that the alkylene oxide is reacted off and thus the catalyst is activated.

[0056] As mentioned above, in the present invention, only in step a) and step b) alkylene oxide is added and the continuous addition of alkylene oxide in step b) is stopped only when the total weight of the alkylene oxide required for the preparation of the polyether alcohol P has been added. The alkylene oxide added in step b) can comprise one or more of propylene oxide, ethylene oxide and butylene oxide, preferably propylene oxide and ethylene oxide, most preferably only propylene oxide.

[0057] The polyether alcohol P prepared in the process of the present invention comprises polyether chains preferably containing a propylene oxide content, an optional butylene oxide content and an optional ethylene oxide content.

[0058] The propylene oxide content of the polyether alcohol P can be at least 10 wt.-% or at least 20 wt.-% or at least 30 wt.-% or at least 40 wt.-% 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.-%. Furthermore, the propylene oxide content of the polyether alcohol P can be at most 100 wt.-% or at most 90 wt.-% or at most 80 wt.-% or at most 70 wt.-% or at most 60 wt.-% or at most 50 wt.-% or at most 40 wt.-% or at most 30 wt.-% or at most 20 wt.-%.

[0059] The polyether alcohol P can have an ethylene oxide content of 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 wt.-% or at least 30 wt.-% or at least 40 wt.-% 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 polyether alcohol P can have an ethylene oxide content of at most 90 wt.-% or at most 80 wt.-% or at most 70 wt.-% or at most 60 wt.-% or at most 50 wt.-% or at most 40 wt.-% or less than 30 wt.-% or at most 25 wt.-% or at most 20 wt.-% or at most 15 wt.-% or at most 12 wt.-%.

[0060] The polyether chain of the polyether alcohol P can not comprise an ethylene oxide content, but can comprise only a propylene oxide and / or a butylene oxide content, suitably only a propylene oxide content.

[0061] Further, the polyether alcohol P can comprise primary hydroxyl groups. The polyether alcohol P can have a primary hydroxyl content of 0% or at least 1% or at least 3% or at least 5% or at least 10% or at least 20% or at least 30%. Further, the polyether alcohol P can have a primary hydroxyl content of 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 at most 20% or at most 15% or at most 10% or at most 5%.

[0062] Further, the polyether alcohol P can have a functionality of 0.8 to 8, preferably 1 to 8, more preferably 2 to 6, more preferably 2 to 4, more preferably 2.5 to 3.5, most preferably 2.7 to 3.3.

[0063] Preferably, at the beginning of step b), the addition rate of the alkylene oxide is increased until the target addition rate is reached, and then preferably the target addition rate is maintained until the end of step b).

[0064] In the present application, the starter compound S2 has an equivalent weight of 10 g / mol to 300 g / mol. Preferably, the starter compound S2 has an equivalent weight of 10 g / mol to 250 g / mol, more preferably 10 g / mol to 200 g / mol, more preferably 10 g / mol to 150 g / mol, more preferably 10 g / mol to 100 g / mol, more preferably 10 g / mol to 80 g / mol, more preferably 10 g / mol to 70 g / mol, more preferably 10 g / mol to 60 g / mol, more preferably 20 g / mol to 50 g / mol, more preferably 25 g / mol to 40 g / mol, most preferably 30 g / mol to 35 g / mol.

[0065] Further, preferably, the starter compound S2 is a multifunctional alcohol typically containing 1 to 8 or 2 to 6 or 2 to 4 hydroxyl groups. Examples of such alcohols include n-butanol, allyl alcohol, diols, glycerol, pentaerythritol, trimethylolpropane, triethanolamine, sorbitol, mannitol and sucrose. Preferably, the starter compound S2 is selected from the group consisting of diols, glycerol, pentaerythritol, trimethylolpropane, triethanolamine, sorbitol and mannitol. Advantageously, mono propylene glycol (MPG), glycerol or a combination of both can be used as the starter compound S2.

[0066] Preferably, at the beginning of step c), the rate of addition of the starter compound S2 is increased until the target rate of addition is reached and then preferably maintained until the end of step c).

[0067] Further, in the present application, preferably, once the above-mentioned target rates of addition of alkylene oxide and starter compound S2 have been reached, the weight ratio of the rate of addition of alkylene oxide to the rate of addition of starter compound S2 is from 2:1 to 10:1 or from 3:1 to 8:1. In particular, preferably, the latter weight ratio is less than the weight ratio before the target rates of addition have been reached, wherein in the earlier stage the weight ratio of the rate of addition of alkylene oxide to the rate of addition of starter compound S2 can be from 8:1 to 30:1 or from 10:1 to 20:1.

[0068] In the present application, step c) is stopped before step b) is stopped. Additionally, step c) is stopped once less than 80% of the total weight of alkylene oxide required to make the polyether alcohol P has been added in step b). In particular, step c) can be stopped once from 5% to less than 80% or from 10% to less than 80% or from 15% to less than 80% or from 20% to less than 80% or from 25% to less than 80% or from 30% to less than 80% or from 50% to less than 80% or from 60% to less than 80% or from 65% to 79% or from 70% to 79% or from 75% to 79% or from 76% to 79% of the total weight of alkylene oxide required to make the polyether alcohol P has been added in step b).

[0069] Further, in the present application, preferably, the total amount of starter compound S2 added in step c) is from 0.1 wt% to 25 wt% or from 0.5 wt% to 25 wt% or from 2 wt% to 25 wt% or from 5 wt% to 25 wt% or from 6 wt% to 22 wt% or from 10 wt% to 18 wt% based on the sum of the total amount of starter compound S2 added in step c) and the total amount of alkylene oxide added in step b).

[0070] In the present application, the continuous addition of alkylene oxide in step b) can be from 100 to 600 kg / m 3 / hr, or 150 to 400 kg / m 3 / hr, or 150 to 400 kg / m 3 / hr, or 150 to 350 kg / m 3 / hr, or 180 to 300 kg / m 3 / hr, or 200 to 270 kg / m 3 / hr, or 200 to less than 250 kg / m 3 / hr, or 220 to less than 250 kg / m 3 / hr, or 230 to 245 kg / m 3 / hr.

[0071] Furthermore, the present application relates to a polyether alcohol obtainable by the above-mentioned process.

[0072] The present application also relates to a process for preparing a polyurethane foam, which comprises reacting a polyether alcohol with a polyisocyanate in the presence of a blowing agent, wherein the polyether alcohol is a polyether alcohol obtained or obtainable by the above-mentioned batch process, and wherein the polyether alcohol is preferably a polyether polyol as described above.

[0073] Furthermore, the present application relates to a process for preparing a polyurethane foam, which comprises preparing a polyether alcohol P having a hydroxyl number equal to or below 115 mg KOH / g according to the above-mentioned batch process, followed by reacting the polyether alcohol with a polyisocyanate in the presence of a blowing agent.

[0074] In the above-mentioned process for preparing a polyurethane foam, the polyether alcohol is reacted with a polyisocyanate in the presence of a blowing agent.

[0075] The polyisocyanate can comprise an aromatic polyisocyanate or an aliphatic polyisocyanate, preferably an aromatic polyisocyanate.

[0076] The aromatic polyisocyanate may, for example, comprise toluene diisocyanate (TDI) or a polymeric TDI, xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenylmethane diisocyanate (MDI) or a polymeric MDI (i.e. polymeric methylene polyphenyl isocyanate) or a modified product thereof. Preferably, the aromatic polyisocyanate comprises toluene diisocyanate (TDI), i.e. non-polymeric TDI. The TDI can be a mixture of 80 wt% 2,4-TDI and 20 wt% 2,6-TDI, which mixture is sold under the name “TDI-80”.

[0077] Furthermore, the aliphatic polyisocyanate may, for example, comprise hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, lysine diisocyanate or isophorone diisocyanate or a modified product thereof.

[0078] Furthermore, the polyisocyanate can comprise any mixture of two or more of the aforementioned polyisocyanates. For example, the polyisocyanate can comprise a mixture of TDI and MDI, in particular a mixture wherein the weight ratio of TDI:MDI is from 10:90 to 90:10.

[0079] The blowing agent can comprise a chemical blowing agent and / or a physical (non-chemical) blowing agent. In the present specification, a "chemical blowing agent" refers to a blowing agent which only provides a blowing effect after having undergone a chemical reaction with another compound. In case the blowing agent comprises a chemical blowing agent, the chemical blowing agent preferably comprises water. Water reacts with the isocyanate groups of the polyisocyanate, thereby releasing carbon dioxide, which results in the blowing taking place.

[0080] However, other suitable blowing agents can additionally or alternatively be used, such as acetone, gaseous or liquid carbon dioxide, halogenated hydrocarbons, aliphatic alkanes and cycloaliphatic alkanes.

[0081] Due to the ozone-depleting effect of fully chlorinated fluorinated alkanes (CFCs), the use of this type of blowing agent is generally not preferred, but they can be used. Halogenated alkanes wherein at least one hydrogen atom is not replaced by a halogen atom (including the so-called HCFCs) have no or less ozone-depleting effect and are therefore preferred halogenated hydrocarbons for use in physically blown foams. One suitable HCFC-type blowing agent is 1-chloro-l,l-difluoroethane. Another halogenated alkane of this type which is suitable for use as a blowing agent is dichloromethane.

[0082] The aforementioned blowing agents can be used individually or in a mixture of two or more.

[0083] The amount of blowing agent 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 relatively high amount of blowing agent, and vice versa. The skilled person can easily determine the amount of blowing agent (physical and / or chemical blowing agent) needed to obtain the desired foam density.

[0084] Water can be used as blowing agent in an amount of at least 0.1 parts by weight per hundred parts by weight of polyether alcohol (pphp) or at least 0.5 pphp or at least 1 pphp. Furthermore, water can be used as blowing agent in an amount of at most 10 parts by weight per hundred parts by weight of polyether alcohol (pphp) or at most 5 pphp or at most 3 pphp or at most 2 pphp.

[0085] In case of halogenated hydrocarbons, aliphatic alkanes and cycloaliphatic alkanes, the amount of blowing agent can be from 1 to 50 parts per hundred parts by weight of polyether alcohol (pphp), suitably from 1 to 30 pphp, more suitably from 1 to 20 pphp.

[0086] Further, preferably, the polyurethane foam that can be made is a flexible polyurethane foam. Further, the flexible polyurethane foam is suitably a slabstock foam. In the present specification, "slabstock foam" means a foam made by applying free rise (unconfined rise) of the foam.

[0087] The isocyanate index (or NCO index) can vary over a wide range and can be from 60 to 120. In particular, the isocyanate index can 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 can be at least 70 or at least 80 or at least 90.

[0088] In the present specification, the "isocyanate index" is calculated as 100 times the molar 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 isocyanate)] * 100, where "theoretical amount of isocyanate" equals 1 equivalent of isocyanate (NCO) groups per 1 equivalent of isocyanate-reactive groups.

[0089] Such "isocyanate-reactive groups" described above include, for example, OH groups from the polyether alcohol and from any water that can be used as a blowing agent. Isocyanate groups also react with water.

[0090] Additionally, other components can also be present during the polyurethane foam production process described above, such as one or more polyurethane catalysts, surfactants, and / or crosslinkers.

[0091] Polyurethane catalysts are known in the art and include many different compounds. Suitable catalysts include tin-based, lead-based, or titanium-based catalysts, preferably tin-based catalysts, such as tin salts of carboxylic acids and dialkyl tin salts. Specific examples are stannous octoate, stannous oleate, dibutyl tin dilaurate, dibutyl tin acetate, and dibutyl tin diacetate. Other suitable catalysts are tertiary amines, such as bis(2,2'-dimethylamino)ethylether, trimethylamine, triethylamine, triethylenediamine, and dimethyl ethanolamine (DMEA). Examples of commercially available tertiary amine catalysts are those sold under the trade names Niax, Tegoamin, and Dabco (all trademarks). Catalysts are typically used in amounts of 0.01 to 2.0 parts by weight per hundred parts by weight of polyether alcohol (php). The preferred amount of catalyst is 0.05 to 1.0 php.

[0092] The use of foam stabilizers (surfactants) is well known. Silicone surfactants are most commonly used as foam stabilizers in the production of polyurethanes. A variety of such silicone surfactants are commercially available. Typically, such foam stabilizers are used in amounts of 0.01 parts by weight to 5.0 parts by weight (pphp) per one hundred parts by weight of polyetherol. Preferred amounts of stabilizer are 0.25 pphp to 2.0 pphp, more preferably 0.75 pphp to 1.5 pphp.

[0093] The use of crosslinking agents in the production of polyurethane foams is also well known. Polyfunctional glycol amines are known to be useful for this purpose. The most commonly used and also useful for the preparation of polyurethane foams, in particular flexible polyurethane foams, polyfunctional glycol amine is diethanolamine, often abbreviated as DEOA. Crosslinking agents can be applied in amounts of up to 2 parts by weight (pphp) per one hundred parts by weight of polyetherol, but most suitably amounts in the range of 0.01 pphp to 0.5 pphp are applied.

[0094] Additionally, other well-known auxiliaries such as colorants, flame retardants, and fillers can also be used during the above-described polyurethane foam preparation method.

[0095] The polyurethane foam preparation method can involve combining the polyisocyanate, polyetherol, blowing agent, catalyst, and optional surfactant, crosslinking agent, flame retardant, colorant, and / or filler in any suitable manner to obtain a polyurethane foam. For example, the method can include mixing the polyetherol, blowing agent, catalyst, and any other optional components except for the polyisocyanate, and then adding the polyisocyanate.

[0096] Further, the above-described polyurethane foam preparation method can include forming the foam into a shaped article prior to its complete curing. Suitably, forming the foam can include pouring the liquid mixture containing all components into a mold prior to gelation completion.

[0097] Further, the present invention relates to a polyurethane foam obtainable by the above-described method for preparing a polyurethane foam, and to a shaped article comprising a polyurethane foam obtained or obtainable by the method.

Claims

1. A batch process for preparing polyether alcohols P having a hydroxyl number of more than 115 mg KOH / g by reacting a starter compound S1 and a starter compound S2 with one or more alkylene oxides in the presence of a composite metal cyanide complex catalyst, the starter compound having one or more active hydrogen atoms, the batch process comprising: a) forming a starter mixture comprising the starter compound S1 and the catalyst and activating the catalyst by adding an alkylene oxide, followed by b) continuously adding alkylene oxide; as well as c) continuously adding the initiator compound S2; in the starter compound S1 having (I) a nominal functionality equal to that of the polyether alcohol P and a hydroxyl number within 10% of the stated hydroxyl number of the polyether alcohol P and / or (II) an equivalent weight of 10 g / mol to 10,000 g / mol; The initiator compound S2 has an equivalent weight of 10 g / mol to 300 g / mol; No alkylene oxide is added between step a) and step b), and the continuous addition of alkylene oxide in step b) is not interrupted until the total weight of alkylene oxide required for the preparation of the polyetherol P has been added; Step c) is stopped before step b) is stopped and step c) is stopped as soon as less than 80% by weight of the total alkylene oxide required for preparing the polyether alcohol P has been added in step b).

2. The process according to claim 1, wherein in step a), 0.5 to 20 wt% of the alkylene oxide is added, based on the weight of the starter mixture before the addition of the alkylene oxide.

3. The process according to claim 1 or 2, wherein in step a) the starter compound S1 is combined with a fresh composite metal cyanide complex catalyst.

4. The method according to any one of claims 1 to 3, wherein step b) is initiated before step c).

5. The process according to claim 1, wherein step c) is stopped as soon as 60% to less than 80% of the total weight of the alkylene oxide required for preparing the polyether alcohol P has been added in step b).

6. The method according to any one of claims 1 to 5, wherein the alkylene oxide added in step b) comprises one or more of propylene oxide, ethylene oxide and butylene oxide.

7. A polyether alcohol obtainable by the method according to any one of claims 1 to 6.

8. A method for preparing a polyurethane foam, comprising reacting a polyether alcohol with a polyisocyanate in the presence of a blowing agent, wherein the polyether alcohol is a polyether alcohol obtained by the method according to any one of claims 1 to 6 or a polyether alcohol according to claim 7.

9. A polyurethane foam obtainable by the method according to claim 8. 10 . A shaped article comprising the polyurethane foam obtained by the method according to claim 8 or the polyurethane foam according to claim 9 .