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 equal to or lower 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 batch process comprises: a) forming a starter mixture comprising a starter compound S1 and the 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 the starter compound S1 has (I) 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 (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 steps a) and b), and the continuous addition of alkylene oxide in step b) is not interrupted before the total weight of alkylene oxide required for producing polyether alcohol P has been added; and step c) begins before step b).

Description

Technical Field

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

[0002] Polyether alcohols (such as polyether polyols) are commonly used in the manufacture of 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 polyalkylene oxide alcohols. Polyether alcohols are typically obtained by reacting an initiator compound or initiator having one or more 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] Advantages associated with DMC-catalyzed production of polyether alcohols are that it is faster and more efficient than conventional methods using potassium hydroxide (KOH) as a catalyst. Further, the DMC-catalyzed process is more environmentally friendly and has a reduced carbon (CO2) footprint. When the DMC-catalyzed process is run as a batch process, the DMC catalyst is first activated. It is known that at the start of the 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 the DMC catalyst. After some 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 added continuously to prepare the desired polyether alcohol.

[0004] It is an object of the present invention to provide a batch process for the production of polyether alcohols that includes the above-described separate initial DMC catalyst activation step, wherein the final polyether alcohol product has a relatively low polydispersity and viscosity, as evidenced by a relatively small fraction of high molecular weight polyether alcohol. Summary of the Invention

[0005] Surprisingly, it has been found that the above object can be achieved by a batch process for the production of polyether alcohols, wherein a polyether alcohol having a hydroxyl value equal to or less than 115 mg KOH / g is prepared by reacting one or more initiator 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 initiator compound are added continuously, characterized in that the continuously added initiator compound is started to be added before the continuous addition of the alkylene oxide is started.

[0006] Accordingly, the present invention relates to a batch process for preparing a polyether polyol P having a hydroxyl value equal to or lower than 115 mg KOH / g by reacting an initiator compound S1 and an initiator compound S2 with one or more alkylene oxides in the presence of a double metal cyanide complex catalyst, the initiator compound having one or more active hydrogen atoms, the batch process comprising:

[0007] a) forming an initiator mixture comprising the initiator compound S1 and the catalyst and activating the catalyst by adding an alkylene oxide, and subsequently

[0008] b) continuously adding an alkylene oxide; and

[0009] c) continuously adding the initiator compound S2;

[0010] wherein

[0011] the initiator compound S1 has (I) a nominal functionality equal to the nominal functionality of the polyether polyol P and a hydroxyl value within 10% of the hydroxyl value of the polyether polyol P and / or (II) an equivalent weight of from 10 g / mol to 10,000 g / mol;

[0012] the initiator compound S2 has an equivalent weight of from 10 g / mol to 300 g / mol;

[0013] no alkylene oxide is added between steps a) and b), and the continuous addition of the alkylene oxide in step b) is not interrupted until the total weight of the alkylene oxide required to prepare the polyether polyol P has been added; and

[0014] step c) is started before step b).

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

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

[0017] Furthermore, the present invention relates to a polyurethane foam obtainable by the above process for preparing a polyurethane foam, and a shaped article comprising a polyurethane foam obtainable or capable of being obtained by said process. DETAILED DESCRIPTION

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

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

[0020] When upper and lower limits are cited for a property, ranges of values defined by combinations of any of the upper limits with any of the lower limits are also implied.

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

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

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

[0024] The term "functionality" or "hydroxyl (OH) functionality" of a polyether polyol refers to the number of hydroxyl groups per molecule of the polyether polyol. The nominal functionality of the polyether polyol is the same as the nominal functionality of its initiator compound (initiator). Unless otherwise specified, 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 polyol by its equivalent weight.

[0025] The term "primary hydroxyl content" (or "PHC") as used herein refers to the relative proportion (in %) of primary hydroxyl groups in the polyether polyol based on the total number of hydroxyl groups including primary and secondary hydroxyl groups. The primary hydroxyl content can be determined in accordance with ASTM D4273.

[0026] The terms "ethylene oxide content" and "propylene oxide content" in relation to a polyether polyol refer to those portions of the polyether polyol that are respectively derived from ethylene oxide and propylene oxide. 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 weight of the alkylene oxides. The ethylene oxide content can be determined in accordance with ASTM D4875.

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

[0028] In the present invention, the polyether alcohol P has a hydroxyl value equal to or lower than 115 mg KOH / g, suitably lower than 115 mg KOH / g. The hydroxyl value of the polyether alcohol P can be at least 2 mg KOH / g or at least 4 mg KOH / g or at least 6 mg KOH / g or at least 8 mg KOH / g or at least 10 mg KOH / g or at least 15 mg KOH / g or at least 20 mg KOH / g or at least 25 mg KOH / g or at least 30 mg KOH / g or at least 35 mg KOH / g or at least 40 mg KOH / g or at least 45 mg KOH / g or at least 50 mg KOH / g. In addition, the hydroxyl value of the polyether alcohol P is at most 115 mg KOH / g, and can be at most 100 mg KOH / g or at most 90 mg KOH / g or at most 80 mg KOH / g or at most 70 mg KOH / g or at most 60 mg KOH / g or at most 50 mg KOH / g or at most 40 mg KOH / g or at most 30 mg KOH / g or at most 20 mg KOH / g.

[0029] In addition, in the present invention, the polyether alcohol P contains an ether bond (or ether unit). In addition, the polyether alcohol may additionally contain an ester bond (or ester unit) and / or a carbonate bond (or carbonate unit). Preferably, the polyether alcohol does not contain an ester bond (or ester unit). In addition, preferably, the polyether alcohol does not contain a carbonate bond (or carbonate unit). Further, the polyether alcohol may consist of ether bonds.

[0030] In addition, in the present invention, the polyether alcohol P contains one or more hydroxyl groups. Therefore, 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 containing an initiator compound S1 and a double metal cyanide complex catalyst is formed. Step a) is carried out before steps b) and c). Preferably, in step a), the initiator mixture is formed in a reactor. Alternatively, the initiator mixture can be formed outside the reactor, and then the thus obtained initiator mixture is charged into the reactor.

[0032] Therefore, in the method of the present invention, a double metal cyanide complex catalyst is used. The double metal cyanide complex catalyst is also commonly referred to as a double metal cyanide (DMC) catalyst. The double metal cyanide complex catalyst is 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] 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 varies according to the atomic balance of the metal, the number of organic ligands to be coordinated, etc.

[0035] 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, as is known in the art, other metals and oxidation states can also be used.

[0036] In the above formula (1), R is an organic ligand, preferably at least one compound selected from the group consisting of alcohols, ethers, ketones, esters, amines, and amides. As such an organic ligand, a water-soluble organic ligand can be used. Specifically, one or more compounds selected from tert-butanol, n-butanol, isobutanol, tert-pentanol, isopentanol, N,N-dimethylacetamide, glyme (ethylene glycol dimethyl ether), diglyme (diethylene glycol dimethyl ether), triglyme (triethylene glycol dimethyl ether), ethylene glycol monoter-butyl ether, isopropanol, and dioxane can be used as the 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 double metal cyanide complex catalyst is tert-butanol. In addition, as the alcohol organic ligand, a polyol can be used, preferably a polyether polyol. 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-butanol as the organic ligand. The double metal cyanide complex catalyst can be produced by a known production method.

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

[0038] (I) The initiator 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

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

[0040] Thus, in the present invention, the 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 initiator compound S1 has a hydroxyl value within 10% of the hydroxyl value of the polyether alcohol P. This means that under requirement (I), the difference between the hydroxyl value of the initiator compound S1 and the hydroxyl value of the polyether alcohol P does not exceed 10%. Preferably, under requirement (I), the initiator compound S1 has a hydroxyl value within 8%, more preferably within 6%, more preferably within 4%, more preferably within 2%, and most preferably within 1% of the hydroxyl value of the polyether alcohol P. Additionally, the hydroxyl value of the initiator compound S1 may be equal to the hydroxyl value of the polyether alcohol P.

[0042] Requirement (I) is satisfied in the case where a portion of the polyether alcohol P prepared in a previous batch of the process according to the present invention is used as the initiator compound S1 in the next batch of the process according to the present invention. Thus, the initiator compound S1 may comprise the same product as 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 the polyether alcohol P prepared in the previous batch may be used as the initiator compound S1 in the next batch. At the end of the batch process, a portion of the thus-prepared polyether alcohol P may remain in the reactor (commonly referred to as "bottoms") and may be used as the initiator compound S1 in the next batch. It is also possible to first store the thus-prepared polyether alcohol P in a separate storage container and then send a portion of it back to the reactor and use it as the initiator compound S1 in the next batch. Prior to step a) of the present process, the above-mentioned "bottoms" may be pretreated, and such pretreatment may include, for example, 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.

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

[0044] Further, under requirement (II), the initiator compound S1 can have a functionality of from 1 to 8, preferably from 2 to 6, more preferably from 2 to 4, more preferably from 2.5 to 3.5, and most preferably from 2.7 to 3.3.

[0045] The situation where only requirement (II) is met but not requirement (I) is the case where another polyether alcohol (another grade) is prepared in the previous batch, and this another polyether alcohol has a nominal functionality different from the nominal functionality of the desired polyether alcohol P to be prepared in the next batch, and / or has a hydroxyl value differing by more than 10% from the hydroxyl value of the polyether alcohol P. When such a grade change is made, a portion of the another polyether alcohol prepared in the previous batch can be used as the initiator compound S1 in the next batch, where the polyether alcohol P is prepared according to the method of the present invention. Thus, the initiator compound S1 can include a product different from the final target product (polyether alcohol P). At most 50% by weight or at most 40% by weight or at most 30% by weight or at most 20% by weight or at most 10% by weight or at most 5% by weight of the total weight of the another polyether alcohol prepared in the previous batch can be used as the initiator compound S1 in the next batch. At the end of the batch process, a portion of the another polyether alcohol thus prepared can remain in the reactor (commonly also referred to as "bottom liquor") and be used as the initiator compound S1 in the next batch in which the polyether alcohol P is prepared. It is also possible to first store the another polyether alcohol thus prepared in a separate storage container and then send a portion of it back to the reactor and use it as the initiator compound S1 in the next batch in which the polyether alcohol P is prepared. Before step a) of the present method, the above "bottom liquor" can be pretreated, and such pretreatment 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.

[0046] Based on the total weight of the final product (polyether alcohol P) in the reactor, the amount of the initiator compound S1 used in step a) of the present method can vary within a wide range. The ratio can be from 1% by weight to 80% by weight, or from 3% by weight to 70% by weight, or from 5% by weight to 60% by weight, or from 7% by weight to 50% by weight, or from 8% by weight to 40% by weight. This 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 initiator compound S1.

[0047] The initiator compound S1 can consist of one initiator compound that meets one or both of requirements (I) and (II). Alternatively, the initiator compound S1 can consist of two or more initiator compounds, suitably a mixture of two initiator compounds, each of which meets one or both of requirements (I) and (II). In the latter case, for example, one of the initiator compounds in the initiator compound can meet requirements (I) and (II), while the other initiator compound can only meet requirement (II). Additionally, in step a) of the present method, one or more initiator compounds other than the initiator compound S1 can be used to form the initiator mixture. Preferably, in the present invention, an initiator compound that does not meet either of requirements (I) and (II) is not used in step a).

[0048] In the present method, step c) starts before step b), which means that the addition of the initiator compound S2 that is continuously added starts before the continuous addition of the alkylene oxide is started. Thus, in the present invention, before starting the continuous addition of the alkylene oxide in step b), the first initiator compound S2 is started to be continuously added to the initiator mixture that was initially formed in step a) and contains (i) the DMC catalyst and (ii) the initiator compound S1, where the initiator compound S1 can be the above-mentioned "bottom liquid" containing the polyether alcohol P prepared in the previous batch according to the method of the present invention. Advantageously, by adding the initiator compound S2 before adding any alkylene oxide, the polydispersity and viscosity of the final polyether alcohol P can be reduced, which can be demonstrated by a relatively small fraction of high molecular weight polyether alcohol in the total polyether alcohol P. A relatively low polydispersity indicates a relatively narrow molecular weight distribution.

[0049] In step a) of the present method, an initiator mixture containing the initiator compound S1 and the double metal cyanide complex catalyst is formed. In step a), the initiator compound S1 can be combined with the double metal cyanide complex catalyst as described above, and the catalyst to be combined with the initiator compound S1 preferably includes a fresh double metal cyanide complex catalyst. In the present specification, a "fresh" catalyst means an unactivated catalyst that has not been used as a catalyst in a chemical method before, specifically an unactivated catalyst that has not been exposed to an alkylene oxide before. However, the fresh catalyst is suitable for use as a catalyst in a chemical method, which means that it is the final catalyst obtained as a product in the catalyst preparation method, rather than any intermediate catalyst or catalyst precursor. In the present specification, a "used" catalyst means a catalyst that has been used as a catalyst in a chemical method before, specifically a catalyst that has been exposed to an alkylene oxide before.

[0050] The above-mentioned fresh double metal cyanide complex catalyst preferably used in step a) should be distinguished from any double metal cyanide complex catalyst that may be present in the initiator compound S1 before forming the initiator mixture containing the initiator compound S1 and the double metal cyanide complex catalyst (preferably containing the fresh double metal cyanide complex catalyst) in step a). The double metal cyanide complex catalyst present in the initiator compound S1 before step a) may be derived from a previous batch, in which the double metal cyanide complex catalyst is also used to prepare a polyether alcohol, and a part of the polyether alcohol may subsequently be used as the initiator compound S1 in the next batch in which the polyether alcohol P is prepared according to the method of the present invention. Therefore, the initiator compound S1 may include a used double metal cyanide complex catalyst. In addition, preferably, the initiator compound S1 does not contain a fresh double metal cyanide complex catalyst.

[0051] Therefore, in the present invention, the polyether alcohol P is prepared in the presence of a double metal cyanide complex catalyst, which comprises (i) a double metal cyanide complex catalyst used in step a) to form an initiator mixture containing the initiator compound S1 and the catalyst, and the catalyst (i) is activated in step a), as further discussed below, and preferably comprises a fresh catalyst, and (ii) optionally a double metal cyanide complex catalyst present in the initiator compound S1 before step a), and the catalyst (ii) may be activated in step a), as further discussed below, and may comprise a used catalyst.

[0052] In the present invention, the initiator compound S2 is added in step c), and step c) starts before step b). In the present invention, the polyether alcohol P is prepared in a reactor. Step a) may be carried out partially (i.e., only catalyst activation) or completely inside the reactor, or alternatively may be carried out partially (i.e., forming the initiator mixture before catalyst activation) or completely outside the reactor, and then the obtained initiator mixture is charged into the reactor. Steps b) and c) are carried out inside the reactor, which means that in step b) the alkylene oxide is continuously added to the reactor, and in step c) the initiator compound S2 is continuously added to the reactor.

[0053] In addition, in the present invention, no alkylene oxide is added between steps a) and b). This means that in the present invention, the alkylene oxide is added only in steps a) and b). In addition, in the present invention, the continuous addition of the alkylene oxide in step b) is not interrupted until the total weight of the alkylene oxide required for preparing the polyether alcohol P has been added. This means that in the present invention, the continuous addition of the alkylene oxide in step b) is not temporarily discontinued, but is stopped only when the total weight of the alkylene oxide required for preparing the polyether alcohol P has been added.

[0054] In the present invention, in step a), an alkylene oxide is added to a starter mixture comprising a starter compound S1 and a double metal cyanide complex catalyst in order to activate the catalyst. A relatively small amount of alkylene oxide may be sufficient to effect such catalyst activation. Based on the weight of the starter mixture before the addition of alkylene oxide (i.e., the alkylene oxide added to activate the catalyst), the amount of alkylene oxide added in step a) may be from 0.5 wt% to 20 wt% or from 1 wt% to 15 wt% or from 2 wt% to 10 wt%. Any alkylene oxide may be added in step a) to effect such catalyst activation. The alkylene oxide added in step a) may comprise one or more of propylene oxide, ethylene oxide and butylene oxide, preferably propylene oxide and / or butylene oxide, most preferably only propylene oxide. Further, as described above, no alkylene oxide is added between steps a) and b). Furthermore, (i) the addition of the alkylene oxide in step a) and (ii) the start of the continuous alkylene oxide addition in step b) are not immediately consecutive to each other. For step b), it is only started after the catalyst has been activated in step a). Such catalyst activation can be confirmed by a drop in the alkylene oxide pressure in the reactor. This pressure drop indicates that the alkylene oxide has reacted away and thus the catalyst has been activated.

[0055] As described above, in the present invention, alkylene oxide is added only in steps a) and b), and the continuous addition of alkylene oxide in step b) is only stopped when the total weight of the alkylene oxide required to prepare the polyether alcohol P has been added. The alkylene oxide added in step b) may comprise 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 alcohol P prepared by the process of the present invention comprises a polyether chain preferably containing a propylene oxide content, an optional butylene oxide content and an optional ethylene oxide content.

[0057] The propylene oxide content of the polyether alcohol P may 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%. Further, the propylene oxide content of the polyether alcohol P may 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%.

[0058] The ethylene oxide content of the polyether alcohol P can 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. Additionally, the ethylene oxide content of the polyether alcohol P can 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 chain of the polyether alcohol P may not contain an ethylene oxide content, but may contain only a propylene oxide and / or a butylene oxide content, suitably only a propylene oxide content.

[0060] In addition, the polyether alcohol P may contain primary hydroxyl groups. The primary hydroxyl content of the polyether alcohol P can 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%. Additionally, the primary hydroxyl content of the polyether alcohol P can 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] In addition, 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, and 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 the target addition rate is reached, and then preferably the target addition rate is maintained until the end of step b).

[0063] In the present invention, the initiator compound S2 has an equivalent weight of 10 g / mol to 300 g / mol. Preferably, the 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, and most preferably 30 g / mol to 35 g / mol.

[0064] Furthermore, preferably, the initiator compound S2 is a polyfunctional alcohol usually 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 initiator compound S2 is selected from the group consisting of diols, glycerol, pentaerythritol, trimethylolpropane, triethanolamine, sorbitol, and mannitol. Advantageously, monopropylene glycol (MPG), glycerol, or a combination of both can be used as the initiator compound S2.

[0065] In the present invention, step c) starts before step b). Preferably, step b) starts before 4 wt% or 3 wt% or 2 wt% or 1 wt% or 0.5 wt% of the total weight of the initiator compound S2 required for preparing the polyether alcohol P has been added in step c).

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

[0067] Furthermore, in the present invention, preferably, once the above 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, preferably, the latter weight ratio is less than the weight ratio before the said target addition rate has been reached, where in the earlier stage, the weight ratio of the addition rate of the alkylene oxide to the addition rate of the initiator compound S2 can be from 8:1 to 30:1 or from 10:1 to 20:1.

[0068] In the present invention, preferably, step c) is stopped before step b) is stopped. In particular, step c) can be stopped once 5% to 99% or 10% to 99% or 15% to 99% or 20% to 99% or 25% to 99% or 30% to 99% or 50% to 99% or 60% to 97% or 70% to 95% or 75% to 93% or 80% to 90% or 80% to 87% of the total weight of the alkylene oxide required for preparing the polyether alcohol P has been added in step b). Advantageously, by stopping step c) in which the initiator compound S2 is continuously added at a relatively late stage before step b), the polydispersity and viscosity of the final polyether alcohol P can be reduced, which can be demonstrated by a relatively small fraction of high molecular weight polyether alcohol in the total polyether alcohol P. A relatively low polydispersity indicates a relatively narrow molecular weight distribution.

[0069] Furthermore, in the present invention, preferably, 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), the total amount of the starter compound S2 added in step c) is 0.1% to 25% by weight or 0.5% to 25% by weight or 2% to 25% by weight or 5% to 25% by weight or 6% to 22% by weight or 10% to 18% by weight.

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

[0071] The present invention also relates to a method for producing 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 by or obtainable by the above batch method, and wherein the polyether alcohol is preferably a polyether polyol as described above.

[0072] Furthermore, the present invention relates to a method for producing a polyurethane foam, which comprises preparing a polyether alcohol P having a hydroxyl value equal to or lower than 115 mg KOH / g according to the above batch method, and then reacting the polyether alcohol with a polyisocyanate in the presence of a blowing agent.

[0073] In the above method for producing a polyurethane foam, a polyether alcohol is reacted with a 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 include, for example, 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 of 2,4-TDI and 20% by weight of 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] Furthermore, the polyisocyanate may include any mixture of two or more of the above polyisocyanates. For example, the polyisocyanate may include a mixture of TDI and MDI, especially a mixture in which the weight ratio of TDI:MDI is 10:90 to 90:10.

[0078] The blowing agent may 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 that can provide a foaming effect only after a chemical reaction with another compound. In the case where the blowing agent includes a chemical blowing agent, the chemical blowing agent preferably includes water. Water reacts with the isocyanate groups of the polyisocyanate, thereby releasing carbon dioxide, which causes foaming to occur.

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

[0080] Due to the ozone-depleting effect of fully chlorinated fluorocarbons (CFCs), 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-depleting effect, and thus are preferred halogenated hydrocarbons for physically foamed foams. A suitable HCFC-type blowing agent is 1-chloro-1,1-difluoroethane. Another halogenated alkane of this type suitable for use as a blowing agent is dichloromethane.

[0081] The above-mentioned blowing agents can be used alone or in a mixture of two or more.

[0082] The amount of the 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 the blowing agent, and vice versa. A person skilled in the art can easily determine the amount of the blowing agent (physical and / or chemical blowing agent) required to obtain the desired foam density.

[0083] Water can be used as a 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. In addition, water can be used as a 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.

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

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

[0086] The isocyanate index (or NCO index) can vary within a wide range and can be from 60 to 120. In particular, the isocyanate index can be at most 120, more preferably at most 110, more preferably at most 100, and most preferably at most 90. In addition, the isocyanate index is preferably higher than 60 and can 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 NCO-reactive groups.

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

[0089] In addition, other components may also be present during the above polyurethane foam preparation method, 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 of carboxylic acids and dialkyltin salts. Specific examples are stannous octoate, stannous oleate, dibutyltin dilaurate, dibutyltin diacetate, and di-n-butyltin diacetate. Other suitable catalysts are tertiary amines such as 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 catalysts are generally used in an amount of 0.01 to 2.0 parts by weight (php) per hundred parts by weight of polyether alcohol. The preferred amount of the 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. Generally, such foam stabilizers are used in an amount of 0.01 to 5.0 parts by weight per hundred parts by weight of polyether alcohol (pphp). The preferred amount of the stabilizer is 0.25 pphp to 2.0 pphp, more preferably 0.75 pphp to 1.5 pphp.

[0092] The use of crosslinking agents in the production of polyurethane foams 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, especially flexible polyurethane foams, is diethanolamine, commonly abbreviated as DEOA. The application amount of the crosslinking agent can be up to 2 parts per hundred parts by weight (pphp) of the polyether alcohol, but an amount in the range of 0.01 pphp to 0.5 pphp is most suitably applied.

[0093] In addition, during the above polyurethane foam preparation method, other well-known auxiliaries can also be used, such as colorants, flame retardants, and fillers.

[0094] The polyurethane foam preparation method may involve combining polyisocyanates, polyether alcohols, blowing agents, catalysts, and optionally surfactants, crosslinking agents, flame retardants, colorants, and / or fillers in any suitable manner to obtain a polyurethane foam. For example, the method may include mixing the polyether alcohol, blowing agent, catalyst, and any other optional components other than the polyisocyanate, and then adding the polyisocyanate.

[0095] Furthermore, the above polyurethane foam preparation method may include forming the foam into a shaped article before the foam is fully cured. Appropriately, forming the foam may include pouring the liquid mixture containing all components into a mold before gelation is complete.

[0096] In addition, the present invention relates to a polyurethane foam capable of being obtained by the above method for preparing a polyurethane foam, and a shaped article comprising the polyurethane foam obtained or capable of being obtained by the method.

Claims

1. A batch process for preparing a polyether polyol P having a hydroxyl value equal to or less than 115 mg KOH / g by reacting an initiator compound S1 and an initiator compound S2 with one or more alkylene oxides in the presence of a double metal cyanide complex catalyst, wherein the initiator compound has one or more active hydrogen atoms, and the batch process comprises: a) forming an initiator mixture comprising the initiator compound S1 and the catalyst and activating the catalyst by adding an alkylene oxide, and then b) continuously adding an alkylene oxide; and c) continuously adding the initiator compound S2; wherein the initiator compound S1 has (I) a nominal functionality equal to the nominal functionality of the polyether polyol P and a hydroxyl value within 10% of the hydroxyl value of the polyether polyol P and / or (II) an equivalent weight of from 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 b), and the continuous addition of the alkylene oxide in step b) is not interrupted until the total weight of the alkylene oxide required to prepare the polyether polyol P has been added; and step c) starts before step b).

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

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

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

5. The method according to claim 4, wherein step c) stops once 5% to 99% of the total weight of the alkylene oxide required to prepare the polyether polyol 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 polyol obtainable by the method according to any one of claims 1 to 6.

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

9. A polyurethane foam obtainable by the method according to claim 8.

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