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 of greater than 115 mg KOH / g by reacting a starter compound S1 having one or more active hydrogen atoms and a starter compound S2 having one or more alkylene oxides in the presence of a composite metal cyanide complex catalyst, the present invention relates to a batch process comprising: a) forming a starter mixture comprising a starter compound S1 and a catalyst and activating the catalyst by adding more than 10% by weight of alkylene oxide based on the weight of the starter mixture prior to the addition of alkylene oxide, followed by b) continuously adding alkylene oxide; and c) continuously adding an initiator compound S2; wherein the starter compound S1 has (I) a nominal functionality equal to the nominal functionality of the polyether alcohol P and a number of hydroxyl groups within 10% of the number of hydroxyl groups 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 from 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 before the total weight of alkylene oxide required to produce polyether alcohol P has been added.

Description

Technical Field

[0001] The present invention relates to a method for preparing a polyether alcohol, a polyether alcohol obtainable by the method, a method for preparing a polyurethane foam using the polyether alcohol, a polyurethane foam obtainable by the method, and a shaped article comprising the polyurethane foam. Background Art

[0002] Polyether alcohols (such as polyether polyols) are commonly used to make polyurethane foams, such as flexible polyurethane foams, which have been widely used 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 (such as glycerol) having one or more active hydrogen atoms with one or more alkylene oxides (such as ethylene oxide and propylene oxide). Known suitable catalysts for this reaction include composite metal cyanide complex catalysts, which are also commonly referred to as double metal cyanide (DMC) catalysts.

[0003] Advantages associated with DMC-catalyzed production of polyether alcohols are that it is faster and more efficient than conventional processes using potassium hydroxide (KOH) as a catalyst. Furthermore, DMC-catalyzed processes are more environmentally friendly and have a reduced carbon (CO2) footprint. When a DMC-catalyzed process is run as a batch process, the DMC catalyst is first activated. It is known that at the start of a batch process, a small amount of alkylene oxide (e.g., propylene oxide) is combined with a reactive compound (such as some polyether alcohol from a previous batch) in the presence of a DMC catalyst. After a period of time, the DMC catalyst becomes activated, as indicated by a drop in alkylene oxide pressure. At some point after activation, more alkylene oxide and initiator can then be added continuously to produce the desired polyether alcohol.

[0004] WO201703748 discloses a method for preparing a polyether polyol product, the method comprising: a) activating a DMC catalyst complex in the presence of: i) an alkoxylation starter having a hydroxyl equivalent weight of 50% to 100% of the hydroxyl equivalent weight of the polyether polyol product; and ii) up to 10% by weight of 1,2-propylene oxide based on the weight of the alkoxylation starter; b) reacting a polyol containing at least 50% by weight of 1,2-propylene oxide under polymerization conditions. The method comprises the following steps: continuously feeding an alkylene oxide to the activated DMC catalyst, wherein starting from the beginning 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 feeding in step b) has been completed, and then the feeding of the low molecular weight starter is stopped while the alkylene oxide feeding is continued, wherein the total weight of the low molecular weight starter added in step b) is 0.2% to 25% of the total weight of the alkylene oxide added in step b).

[0005] The present invention provides a batch-wise polyetherol production process comprising a separate initial DMC catalyst activation step, wherein the final polyetherol product has relatively low polydispersity and viscosity, as evidenced by a relatively small fraction of high molecular weight polyetherols. The relatively low polydispersity indicates a relatively narrow molecular weight distribution. Summary of the Invention

[0006] Surprisingly, it has been found that the above-mentioned objects can be achieved by a batch process for the production of polyether alcohols, wherein polyether alcohols having a hydroxyl number of more than 115 mg KOH / g are prepared by reacting one or more starter compounds with one or more alkylene oxides in the presence of a composite metal cyanide complex catalyst (double metal cyanide (DMC) catalyst), and wherein the alkylene oxide and the starter compound are added continuously, characterized in that in a separate initial DMC catalyst activation step, more than 10% by weight of the alkylene oxide, based on the weight of the starter mixture comprising the starter compound and the catalyst, is added.

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

[0008] a) forming a starter mixture comprising the starter compound S1 and a catalyst, and activating the catalyst by adding greater than 10% by weight of an alkylene oxide, based on the weight of the starter mixture before the addition of the alkylene oxide, and subsequently

[0009] b) continuously adding alkylene oxide; and

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

[0011] in

[0012] 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 hydroxyl number of the polyether alcohol P and / or (II) an equivalent weight of 10 g / mol to 10,000 g / mol;

[0013] The initiator 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 until the total weight of alkylene oxide required for the preparation of the polyetherol P has been added.

[0015] Furthermore, the present invention relates to a polyether alcohol obtainable by the above-described process.

[0016] The present invention also relates to a process for preparing polyurethane foam, which comprises reacting a polyetherol with a polyisocyanate in the presence of a blowing agent, wherein the polyetherol is a polyetherol obtainable or obtainable by the process described above.

[0017] Furthermore, the present invention relates to a polyurethane foam obtainable by the above-described method for producing a polyurethane foam, and a shaped article comprising the polyurethane foam obtained or obtainable by said method. DETAILED DESCRIPTION

[0018] Although the methods and compositions of the present invention may be described as "comprising," "containing," or "including," respectively, one or more of the various described steps or components, they may also "consist essentially of" or "consist of," respectively, the one or more various described steps or components.

[0019] In the context of the present invention, where the composition comprises two or more components, these are selected in such a total amount that does not exceed 100% by weight.

[0020] Where upper and lower limits are cited for a property, a range of values ​​defined by the combination of any of the upper limits with any of the lower limits is also implied.

[0021] The term "molecular weight" (or "MW") is used herein to refer to number average molecular weight, unless otherwise stated or the context requires otherwise.The number average molecular weight of the polyether alcohols can be measured by gel permeation chromatography (GPC) or vapor pressure osmometry (VPO).

[0022] As used herein, the term "hydroxyl (OH) value" or "hydroxyl (OH) number" refers to the number of milligrams of potassium hydroxide equivalent to the hydroxyl content in one gram of polyether alcohol, as determined by wet titration. Therefore, the OH value or OH number is expressed in mg KOH / g. The hydroxyl number can be determined according to ASTM D4274.

[0023] As used herein, the term "equivalent weight" (or "EW") refers to the weight of the polyetherol per reactive site. The equivalent weight is 56,100 divided by the hydroxyl number of the polyetherol.

[0024] The term "functionality" or "hydroxyl (OH) functionality" of a polyetherol refers to the number of hydroxyl groups per molecule of the polyetherol. The nominal functionality of a polyetherol is the same as the nominal functionality of its starter compound (initiator). Unless otherwise indicated, the functionality refers to the actual average functionality, which may be lower than the nominal functionality and is determined by dividing the number average molecular weight of the polyetherol by the equivalent weight of the polyetherol.

[0025] The term "primary hydroxyl content" (or "PHC") used herein refers to the relative proportion (in %) of primary hydroxyl groups in a polyetherol 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.

[0026] The terms "ethylene oxide content" and "propylene oxide content" with respect to polyetherols refer to those portions of the polyetherol that are derived from ethylene oxide and propylene oxide, respectively. These contents may also be referred to as ethylene oxide content and propylene oxide content, respectively. Furthermore, these contents are herein based on the total alkylene oxide weight. Ethylene oxide content can be determined according to ASTM D4875.

[0027] The process of the present invention is a batch process. In a batch process, the desired product, in the present invention the polyether alcohol P, is not prepared continuously in a reactor, but rather is prepared in a reactor over a certain period of time, after which at least a portion of the product is recovered, after which a new batch can be started.

[0028] In the present invention, 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 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. Furthermore, the hydroxyl number of the polyether alcohol P may 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.

[0029] Furthermore, in the present invention, the polyether alcohol P contains ether bonds (or ether units). Furthermore, the polyether alcohol may further contain ester bonds (or ester units) and / or carbonate bonds (or carbonate units). Preferably, the polyether alcohol does not contain ester bonds (or ester units). Furthermore, preferably, the polyether alcohol does not contain carbonate bonds (or carbonate units). Furthermore, the polyether alcohol may consist of ether bonds.

[0030] Furthermore, in the present invention, the polyether alcohol P contains one or more hydroxyl groups. Thus, the polyether alcohol P can be a polyether monool or a polyether polyol. A monool is an alcohol containing one hydroxyl group, while a polyol is an alcohol containing two or more hydroxyl groups.

[0031] In step a) of the present method, an initiator mixture comprising initiator compound S1 and a composite metal cyanide complex catalyst is formed. Step a) is performed before step b) and step c) are performed. Preferably, in step a), the initiator mixture is formed in a reactor. Alternatively, the initiator mixture can be formed outside the reactor, and the initiator mixture thus obtained is then loaded into the reactor.

[0032] Therefore, in the method of the present invention, a composite metal cyanide complex catalyst is used. Composite metal cyanide complex catalysts are also commonly referred to as double metal cyanide (DMC) catalysts. Composite metal cyanide complex catalysts are generally represented by the following formula (1):

[0033] (1)M 1 a [M 2 b (CN) c ] d .e(M 1 f X g ).h(H20).i(R)

[0034] Among them, M 1and M 2 Each 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 that can vary depending on the atomic balance of the metal, the number of organic ligands to be coordinated, and the like.

[0035] In the above formula (1), M 1 Preferably, it is a metal selected from Zn(II) or Fe(II). 2 Preferably it is a metal selected from Co(III) or Fe(III). However, other metals and oxidation states may also be used as known in the art.

[0036] In the above formula (1), R is an organic ligand, preferably at least one compound selected from the group consisting of alcohol, ether, ketone, ester, amine and amide. As such an organic ligand, a water-soluble organic ligand can be used. Specifically, one or more compounds selected from tert-butyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-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-tert-butyl ether, isopropyl alcohol and dioxane can be used as an organic ligand. 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 composite metal cyanide complex catalyst is tert-butyl alcohol. In addition, as an alcohol organic ligand, a polyol, preferably a polyether polyol, can be used. More preferably, poly(propylene glycol) having a number average molecular weight in the range of 500 to 2,500 daltons, preferably 800 to 2,200 daltons, can be used as the organic ligand or one of the organic ligands. Most preferably, such poly(propylene glycol) is used in combination with tert-butyl alcohol as the organic ligand. The composite metal cyanide complex catalyst can be produced by known production methods.

[0037] In the present invention, the initiator compound S1 satisfies one or both of the following two requirements (I) and (II):

[0038] (I) the starter compound S1 has a nominal functionality equal to that of the polyether alcohol P and a hydroxyl number within 10% of the hydroxyl number of the polyether alcohol P, and / or

[0039] (II) The initiator compound S1 has an equivalent weight of 10 g / mol to 10,000 g / mol.

[0040] Therefore, in the present invention, compound S1 may satisfy only requirement (I), or may satisfy only requirement (II), or may satisfy both requirements (I) and (II).

[0041] Under requirement (I), the starter compound S1 has a hydroxyl number within 10% of the hydroxyl number of the polyether alcohol P. This means that under requirement (I), the hydroxyl number of the starter compound S1 does not differ from the hydroxyl number of the polyether alcohol P by more than 10%. Preferably, under requirement (I), the starter compound S1 has a hydroxyl number within 8%, more preferably within 6%, more preferably within 4%, more preferably within 2%, and most preferably within 1% of the hydroxyl number of the polyether alcohol P. Alternatively, the hydroxyl number of the starter compound S1 may be equal to the hydroxyl number of the polyether alcohol P.

[0042] Requirement (I) is satisfied when a portion of the polyether alcohol P produced in a previous batch of the process according to the invention is used as the starter compound S1 in a subsequent batch of the process according to the invention. Thus, the starter compound S1 may comprise the same product as the final target product (polyether alcohol P). Up to 50% by weight, or up to 40% by weight, or up to 30% by weight, or up to 20% by weight, or up to 10% by weight, or up to 5% by weight of the total weight of the polyether alcohol P produced in the previous batch may be used as the starter compound S1 in the subsequent batch. At the end of the batch process, a portion of the polyether alcohol P thus produced may remain in the reactor (often also referred to as the "bottom liquid") and may be used as the starter compound S1 in the next batch. It is also possible to initially store the polyether alcohol P thus produced in a separate storage container and then return a portion of it to the reactor and use it as the starter compound S1 in the next batch. Prior to step a) of the present process, the above-mentioned "bottom liquor" may be subjected to a pretreatment, wherein such pretreatment may, for example, comprise stripping using 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.

[0043] Under requirement (II), the initiator compound S1 has an equivalent weight of 10 g / mol to 10,000 g / mol. Under requirement (II), the initiator compound S1 may 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 requirement (II), the starter compound S1 may 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.

[0044] Furthermore, under requirement (II), the starter compound S1 may 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.

[0045] A case in which only requirement (II) is met, but not requirement (I), is when another polyether alcohol (another grade) was prepared in a preceding batch, this other polyether alcohol having a nominal functionality different from that of the desired polyether alcohol P to be prepared in the next batch, and / or having a hydroxyl number that differs by more than 10% from that of the 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 starter compound S1 in the next batch in which polyether alcohol P is prepared according to the process of the present invention. Thus, starter compound S1 may contain products other than the final target product (polyether alcohol P). Up to 50% by weight, or up to 40% by weight, or up to 30% by weight, or up to 20% by weight, or up to 10% by weight, or up to 5% by weight of the total weight of the other polyether alcohol prepared in the preceding batch can be used as starter compound S1 in the next batch. At the end of the batch process, a portion of the further polyether alcohol thus prepared can remain in the reactor (often also referred to as "bottom liquid") and be used as starter compound S1 in the next batch in which polyether alcohol P is prepared. It is also possible to first store the further polyether alcohol thus prepared in a separate storage container, then return a portion of it to the reactor and use it as starter compound S1 in the next batch in which polyether alcohol P is prepared. Prior to step a) of the present process, the aforementioned "bottom liquid" can be subjected to a pretreatment, wherein such pretreatment can, 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 previous batch.

[0046] The amount of starter compound S1 used in step a) of the process can vary within a wide range, based on the total weight of the final product (polyether alcohol P) in the reactor. The proportion can be from 1% to 80% by weight, or from 3% to 70% by weight, or from 5% to 60% by weight, or from 7% to 50% by weight, or from 8% to 40% by weight. This proportion is related to the so-called "build ratio", which is defined in this specification as the ratio of the total weight of the final product in the reactor to the weight of the starter compound S1.

[0047] Initiator compound S1 can be made up of a kind of initiator compound that satisfies one or both of requirement (I) and (II).Alternatively, initiator compound S1 can be made up of a mixture of two or more initiator compounds, suitably a mixture of two initiator compounds, and every kind of compound in this initiator compound satisfies one or both of requirement (I) and (II).In the latter case, for example, a kind of initiator compound in initiator compound can satisfy requirement (I) and (II), and another kind of initiator compound can only satisfy requirement (II).In addition, in addition, in the step a) of present method, one or more initiator compounds except initiator compound S1 can be used for forming initiator mixture.Preferably, in the present invention, in step a), do not use the initiator compound that does not satisfy any one of requirement (I) and (II).

[0048] In the present invention, step b) may be initiated before step c), or step b) and step c) may be initiated simultaneously, or step c) may be initiated before step b). Preferably, step b) is initiated before step c). In the present invention, the polyether alcohol P is prepared in a reactor. However, as described above, step a) may be performed in the reactor, or alternatively, may be performed outside the reactor, after which the starter mixture obtained is charged to the reactor. Steps b) and c) are performed 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).

[0049] In step a) of the present method, an initiator mixture comprising an initiator compound S1 and a composite metal cyanide complex catalyst is formed. In step a), the initiator compound S1 may be combined with a composite metal cyanide complex catalyst as described above, wherein the catalyst to be combined with the initiator compound S1 preferably comprises a fresh composite metal cyanide complex catalyst. In this specification, a "fresh" catalyst means an unactivated catalyst that has not been used as a catalyst in a chemical process before, specifically an unactivated catalyst that has not been exposed to an alkylene oxide before. 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, rather than any intermediate catalyst or catalyst precursor. In this specification, a "used" catalyst means a catalyst that has been used as a catalyst in a chemical process before, specifically a catalyst that has been exposed to an alkylene oxide before.

[0050] 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.

[0051] 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.

[0052] 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).

[0053] 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.

[0054] In the present invention, in step a), alkylene oxide is added to the initiator mixture comprising initiator compound S1 and composite metal cyanide complex catalyst to activate the catalyst. In addition, in the present invention, based on the weight of the initiator mixture before adding alkylene oxide (that is, the alkylene oxide added to activate the catalyst), the amount of the alkylene oxide added in step a) is greater than 10 wt %. Based on the weight of the initiator mixture before adding alkylene oxide, the amount of the alkylene oxide added in step a) can be greater than 10 wt % to 40 wt %, or 11 wt % to 35 wt %, or 12 wt % to 30 wt %, or 13 wt % to 25 wt %, or 14 wt % to 20 wt %. Any alkylene oxide can be added in step a) to realize such catalyst activation. The alkylene oxide added in step a) can include 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 described above, no alkylene oxide is added between steps a) and b). Furthermore, (i) completion of the alkylene oxide addition in step a) and (ii) commencement of the continued alkylene oxide addition in step b) are not immediately followed. Step b) begins only after the catalyst is activated in step a). Such catalyst activation can be confirmed by a drop in the alkylene oxide pressure in the reactor. This drop in pressure indicates that the alkylene oxide has reacted and, therefore, the catalyst has been activated.

[0055] As described above, in the present invention, alkylene oxide is added only in step a) and step b), and the continuous addition of alkylene oxide in step b) is stopped only when the total weight of alkylene oxide required for preparing the polyether alcohol P has been added. The alkylene oxide added in step b) may include one or more of propylene oxide, ethylene oxide and butylene oxide, preferably propylene oxide and ethylene oxide, most preferably only propylene oxide.

[0056] The polyether alcohols P prepared in the process according to the invention comprise polyether chains which preferably contain a propylene oxide content, optionally a butylene oxide content and optionally an ethylene oxide content.

[0057] The polyether alcohol P may have a propylene oxide content of at least 10% by weight, or at least 20% by weight, or at least 30% by weight, or at least 40% by weight, or at least 50% by weight, or at least 60% by weight, or at least 70% by weight, or at least 80% by weight, or at least 90% by weight, or at least 95% by weight, or at least 99% by weight. Furthermore, the polyether alcohol P may have a propylene oxide content of up to 100% by weight, or up to 90% by weight, or up to 80% by weight, or up to 70% by weight, or up to 60% by weight, or up to 50% by weight, or up to 40% by weight, or up to 30% by weight, or up to 20% by weight.

[0058] The ethylene oxide content of the polyether alcohol P may be 0% by weight, or at least 3% by weight, or at least 5% by weight, or at least 10% by weight, or at least 12% by weight, or at least 15% by weight, or at least 20% by weight, or at least 30% by weight, or at least 40% by weight, or at least 50% by weight, or at least 60% by weight, or at least 70% by weight, or at least 80% by weight, or at least 90% by weight. Furthermore, the ethylene oxide content of the polyether alcohol P may be at most 90% by weight, or at most 80% by weight, or at most 70% by weight, or at most 60% by weight, or at most 50% by weight, or at most 40% by weight, or less than 30% by weight, or at most 25% by weight, or at most 20% by weight, or at most 15% by weight, or at most 12% by weight.

[0059] The polyether chains of the polyetherols P may comprise no ethylene oxide content, but may comprise only propylene oxide and / or butylene oxide content, suitably only propylene oxide content.

[0060] Furthermore, the polyether alcohol P may contain primary hydroxyl groups. The primary hydroxyl content of the polyether alcohol P may be 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%. Furthermore, the primary hydroxyl content of the polyether alcohol P 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 at most 20%, or at most 15%, or at most 10%, or at most 5%.

[0061] Furthermore, the polyether alcohol P may 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.

[0062] Preferably, at the start of step b), the addition rate of the alkylene oxide is increased until a target addition rate is reached, and then preferably maintained at this target addition rate until the end of step b).

[0063] In the present invention, initiator compound S2 has an equivalent weight of 10 g / mol to 300 g / mol. Preferably, initiator 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.

[0064] In addition, preferably, initiator compound S2 is a polyfunctional alcohol generally containing 1 to 8 or 2 to 6 or 2 to 4 hydroxyl groups. The example of this type of alcohol includes n-butyl alcohol, allyl alcohol, glycol, glycerol, pentaerythritol, trimethylolpropane, triethanolamine, sorbitol, mannitol and sucrose. Preferably, initiator compound S2 is selected from the group consisting of glycol, glycerol, pentaerythritol, trimethylolpropane, triethanolamine, sorbitol and mannitol. Advantageously, monopropylene glycol (MPG), glycerol or a combination of the two can be used as initiator compound S2.

[0065] Preferably, at the beginning of step c), the addition rate of starter compound S2 is increased until a target addition rate is reached, and then preferably maintained at this target addition rate until the end of step c).

[0066] Furthermore, in the present invention, it is preferred that, once the above-mentioned target addition rates of the alkylene oxide and the initiator compound S2 have been reached, the weight ratio of the addition rate of the alkylene oxide to the addition rate of the initiator compound S2 is from 2: 1 to 10: 1 or from 3: 1 to 8: 1. In particular, it is preferred that the latter weight ratio is smaller than the weight ratio before the target addition rate has been reached, wherein in the earlier stage, the weight ratio of the addition rate of the alkylene oxide to the addition rate of the initiator compound S2 may be from 8: 1 to 30: 1 or from 10: 1 to 20: 1.

[0067] In the present invention, it is preferred that step c) is stopped before step b) is stopped. In particular, step c) can be stopped as soon as 5% to 99% or 10% to 99% or 15% to 99% or 20% to 99% or 25% to 95% or 30% to 90% or 50% to 85% or 60% to less than 80% or 65% to 79% or 70% to 79% or 75% to 79% or 76% to 79% of the total weight of the alkylene oxide required for preparing the polyether alcohol P has been added in step b).

[0068] Furthermore, in the present invention, it is preferred that the total amount of the starter compound S2 added in step c) is 0.1 wt % to 25 wt % or 0.5 wt % to 25 wt % or 2 wt % to 25 wt % or 5 wt % to 25 wt % or 6 wt % to 22 wt % or 10 wt % to 18 wt % based on the total amount of the starter compound S2 added in step c) and the total amount of the alkylene oxide added in step b).

[0069] In the present invention, the continuous addition of alkylene oxide in step b) can be 100 kg / m 3 / hr to 600kg / m 3 / hr is achieved with a space-time yield (STY) of 150 kg / m3 / hr, the STY being expressed in kilograms of polyether alcohol P produced per cubic meter per hour of alkylene oxide addition time in step b), or 150 kg / m3 / hr. 3 / hr to 500kg / m 3 / hr or 150kg / m 3 / hr to 400kg / m 3 / hr or 150kg / m 3 / hr to 350kg / m 3 / hr or 180kg / m 3 / hr to 300kg / m 3 / hr or 200kg / m 3 / hr to 270kg / m 3 / hr or 200kg / m 3 / hr to less than 250kg / m 3 / hr or 220kg / m 3 / hr to less than 250kg / m 3 / hr or 230kg / m 3 / hr to 245kg / m 3 / hr.

[0070] Furthermore, the present invention relates to a polyether alcohol obtainable by the above-described process.

[0071] The present invention also relates to a process for preparing polyurethane foam, which comprises reacting a polyetherol with a polyisocyanate in the presence of a blowing agent, wherein the polyetherol is a polyetherol obtainable or obtainable by the above-described batch process, and wherein the polyetherol is preferably a polyether polyol as described above.

[0072] The present invention furthermore relates to a process for producing polyurethane foams, which comprises preparing a polyetherol P having a hydroxyl number equal to or below 115 mg KOH / g according to the batch process described above and subsequently reacting the polyetherol with a polyisocyanate in the presence of a blowing agent.

[0073] In the above-described process for producing polyurethane foam, polyether alcohol is reacted with polyisocyanate in the presence of a blowing agent.

[0074] The polyisocyanate may include an aromatic polyisocyanate or an aliphatic polyisocyanate, preferably an aromatic polyisocyanate.

[0075] The aromatic polyisocyanate may, for example, include toluene diisocyanate (TDI) or polymeric TDI, xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenylmethane diisocyanate (MDI) or polymeric MDI (i.e., polymethylene polyphenyl isocyanate), or modified products thereof. Preferably, the aromatic polyisocyanate includes toluene diisocyanate (TDI), i.e., non-polymeric TDI. TDI may be a mixture of 80% by weight 2,4-TDI and 20% by weight 2,6-TDI, which is sold as "TDI-80."

[0076] Furthermore, the aliphatic polyisocyanate may include, for example, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, lysine diisocyanate, or isophorone diisocyanate, or modified products thereof.

[0077] In addition, the polyisocyanate may comprise any mixture of two or more of the above-mentioned polyisocyanates. For example, the polyisocyanate may comprise a mixture of TDI and MDI, particularly a mixture in which the weight ratio of TDI:MDI varies from 10:90 to 90:10.

[0078] The blowing agent may comprise a chemical blowing agent and / or a physical (non-chemical) blowing agent. As used herein, a "chemical blowing agent" refers to a blowing agent that provides a foaming effect only after chemically reacting with another compound. Where 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 causes foaming.

[0079] However, other suitable blowing agents may additionally or alternatively be used, such as acetone, gaseous or liquid carbon dioxide, halogenated hydrocarbons, aliphatic alkanes, and cycloaliphatic alkanes.

[0080] Due to the ozone depletion 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 in which at least one hydrogen atom is not replaced by a halogen atom (including so-called HCFCs) have no or less ozone depletion effect and are therefore preferred halogenated hydrocarbons for physically blown foams. One suitable HCFC-type blowing agent is 1-chloro-1,1-difluoroethane. Another halogenated alkanes of this type suitable for use as blowing agents are methylene chloride (dichloromethane).

[0081] The above-mentioned foaming agents may be used alone or in admixture of two or more.

[0082] The amount of blowing agent is determined by the desired density of the polyurethane foam to be produced. For example, a relatively low density can be achieved by using a relatively high amount of blowing agent, and vice versa. A skilled person can readily determine the amount of blowing agent (physical blowing agent and / or chemical blowing agent) required to achieve a desired foam density.

[0083] Water can be used as a blowing agent in an amount of at least 0.1 parts by weight (pphp) per 100 parts by weight of polyether alcohol, or at least 0.5 pphp, or at least 1 pphp. In addition, water can be used as a blowing agent in an amount of up to 10 parts by weight (pphp), or up to 5 pphp, or up to 3 pphp, or up to 2 pphp per 100 parts by weight of polyether alcohol.

[0084] In the case of halogenated hydrocarbons, aliphatic alkanes and alicyclic alkanes, the amount of blowing agent may be 1 to 50 parts per hundred parts by weight of polyether alcohol (pphp), suitably 1 to 30 pphp, more suitably 1 to 20 pphp.

[0085] In addition, preferably, the polyurethane foam that can be prepared is a flexible polyurethane foam. In addition, the flexible polyurethane foam is suitably a block foam. In this specification, "block foam" refers to a foam made by applying the free rise (unconstrained rise) of foam.

[0086] The isocyanate index (or NCO index) may vary within a wide range and may be from 60 to 120. In particular, the isocyanate index may be at most 120, more suitably at most 110, more suitably at most 100, and most suitably at most 90. Furthermore, the isocyanate index is preferably above 60 and may be at least 70, or at least 80, or at least 90.

[0087] In this 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 the "theoretical amount of isocyanate" is equal to 1 equivalent of isocyanate (NCO) groups per 1 equivalent of isocyanate-reactive groups.

[0088] Such "isocyanate-reactive groups" as mentioned above include, for example, OH groups from polyether alcohols and from any water that may be used as blowing agent. Isocyanate groups also react with water.

[0089] Additionally, other components may also be present during the above-described polyurethane foam preparation process, such as one or more polyurethane catalysts, surfactants, and / or crosslinking agents.

[0090] 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 and dialkyltin salts of carboxylic acids. Specific examples are stannous octoate, stannous oleate, dibutyltin dilaurate, dibutyltin acetate and dibutyltin diacetate. Other suitable catalysts are tertiary amines, such as, for example, bis(2,2'-dimethylamino)ethyl ether, trimethylamine, triethylamine, triethylenediamine and dimethylethanolamine (DMEA). Examples of commercially available tertiary amine catalysts are those sold under the trade names Niax, Tegoamin and Dabco (all trademarks). The catalyst is typically used in an amount of 0.01 to 2.0 parts by weight (php) per 100 parts by weight of polyether alcohol. The preferred amount of catalyst is 0.05 php to 1.0 php.

[0091] The use of foam stabilizers (surfactants) is well known. Silicone surfactants are most commonly used as foam stabilizers in polyurethane production. A variety of such silicone surfactants are commercially available. Typically, such foam stabilizers are used in an amount of 0.01 to 5.0 parts by weight per 100 parts by weight of polyether alcohol (pphp). The preferred amount of stabilizer is 0.25 to 2.0 pphp, more preferably 0.75 to 1.5 pphp.

[0092] The use of crosslinking agents in the production of polyurethane foam is also well known. Polyfunctional diolamines are known to be useful for this purpose. The most commonly used polyfunctional diolamine, which can also be used to prepare polyurethane foams, particularly flexible polyurethane foams, is diethanolamine, often abbreviated as DEOA. The crosslinker can be applied in an amount of up to 2 parts by weight per 100 parts by weight of polyether alcohol (pphp), but most suitably, an amount in the range of 0.01 to 0.5 pphp is used.

[0093] Additionally, during the above-mentioned polyurethane foam preparation process, other well-known auxiliary agents such as colorants, flame retardants, and fillers may also be used.

[0094] The polyurethane foam preparation method may involve combining a polyisocyanate, a polyether alcohol, a blowing agent, a catalyst, and optionally a surfactant, a crosslinking agent, a flame retardant, a colorant, and / or a filler in any suitable manner to obtain the polyurethane foam. For example, the method may include mixing the polyether alcohol, the blowing agent, the catalyst, and any other optional components other than the polyisocyanate, and then adding the polyisocyanate.

[0095] Furthermore, the above polyurethane foam preparation method may comprise forming the foam into a shaped article before the foam is fully cured. Suitably, forming the foam may comprise pouring a liquid mixture containing all components into a mould before gelling is complete.

[0096] Furthermore, the present invention relates to a polyurethane foam obtainable by the above-described method for producing a polyurethane foam, and a shaped article comprising the polyurethane foam obtained or obtainable by said method.

Claims

1. A batch process for preparing polyether alcohols P having a hydroxyl number of 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 starter compound having one or more active hydrogen atoms, the batch process comprising: a) forming a starter mixture comprising a starter compound S1 and the catalyst, and activating the catalyst by adding greater than 10% by weight of the alkylene oxide, based on the weight of the starter mixture before the addition of the alkylene oxide, and subsequently 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.

2. The process according to claim 1, wherein in step a), greater than 10% to 40% by weight 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 method according to any one of claims 1 to 4, wherein step c) is stopped before step b) is stopped. 6 . The process according to claim 5 , wherein step c) is stopped as soon as 5 to 99% by weight of the total amount of alkylene oxide required for preparing the polyether alcohol P has been added in step b).

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 .