Batch process for producing polyether polyols using double metal cyanide catalysts

Abstract

The invention relates to a batch process for producing polyether polyols P having a hydroxyl number of greater than 115 mg KOH / g by reacting a starting compound S1, which has a plurality of active hydrogen atoms, and optionally a starting compound S2, which has a plurality of active hydrogen atoms, with one or more alkylene oxides in the presence of a composite metal cyanide complex catalyst, the batch process comprises: a) forming a starter mixture comprising a starter compound S1 and the catalyst, followed by b) continuously adding an alkylene oxide; and c) optionally: continuously adding the starting compound S2; wherein the starting 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 10 g / mol to 500 g / mol; optionally the starting compound S2 has an equivalent weight of from 10 g / mol to 70 g / mol; and no alkylene oxide is added in step a) or between step a) and step b), and the continuous addition of alkylene oxide in step b) is not interrupted before the total weight of alkylene oxide required for producing polyether polyol P has been added.

Description

Technical Field

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

[0002] Polyether polyols are commonly used to manufacture polyurethane foams that have been widely used in a variety of industrial and consumer applications, such as flexible polyurethane foams. Polyether polyols are also commonly referred to as polyalkylene oxide polyols. Polyether polyols are typically obtained by reacting a starting compound or initiator having multiple active hydrogen atoms, such as glycerol, with one or more alkylene oxides, such as ethylene oxide and propylene oxide. Known suitable catalysts for this reaction include complex metal cyanide complex catalysts, which are commonly also referred to as double metal cyanide (DMC) catalysts.

[0003] An advantage associated with DMC-catalyzed production of polyether polyols is that it is faster and more efficient than traditional methods that use potassium hydroxide (KOH) as a catalyst. Further, the DMC-catalyzed method is more environmentally friendly and has a reduced carbon (CO 2 ) footprint. However, when the DMC-catalyzed method is run as a batch process, the DMC catalyst first needs to be activated. It is known that at the start of a batch process, a small amount of alkylene oxide, such as propylene oxide, is combined with a reactive compound, such as some polyether polyol 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 polyol.

[0004] EP3184575A1 discloses a batch process for producing a low molecular weight polyalkylene oxide polyol having a hydroxyl value of 200 mg KOH / g to 500 mg KOH / g, in which a first alkylene oxide block activates the DMC catalyst in a mixture of a double metal cyanide (DMC) catalyst and an initial initiator, followed by addition of a second alkylene oxide block and continuous introduction of one or more initiators. The method of EP3184575A1 includes a separate DMC catalyst activation step, as also described in its examples. In Example 1 of EP3184575A1, a polyether polyol (polyol A) and a DMC catalyst (catalyst A) are charged into a reactor. Then propylene oxide and ethylene oxide are charged to activate the catalyst. This results in an increase in pressure, after which the pressure steadily decreases, indicating that the catalyst is activated. Then the propylene oxide and ethylene oxide feeds are restarted, and after some time the glycerol and propylene glycol feeds are started.

[0005] However, as described above, the separate DMC catalyst activation step takes time and thus prolongs the total production time in the batch polyether polyol production process. An object of the present invention is to provide a batch polyether polyol production process that can have a reduced total batch time. In addition, an object of the present invention is to reduce the total amount of DMC catalyst required in such batch processes while still achieving efficient production. Further, an object of the present invention is to increase the tolerance to impurities such as water that may be present in initiators such as glycerol. Summary of the Invention

[0006] Surprisingly, it has been found that one or more of the above objects can be achieved by a batch polyether polyol production process in which a polyether polyol having a hydroxyl value greater than 115 mg KOH / g is prepared by reacting one or more starting compounds with one or more alkylene oxides in the presence of a complex metal cyanide complex catalyst (double metal cyanide (DMC) catalyst), and in which the alkylene oxides are added continuously, the process being characterized in that the above separate DMC catalyst activation step is omitted, and in that (i) the alkylene oxides are added only in the step of continuously adding the alkylene oxides, and (ii) the continuous addition of the alkylene oxides in the subsequent step is stopped only when the total weight of the alkylene oxides required for preparing the polyether polyol P has been added.

[0007] Accordingly, the present invention relates to a batch process for preparing a polyether polyol P having a hydroxyl value greater than 115 mg KOH / g by reacting a starting compound S 1 and optionally a starting compound S 2 with one or more alkylene oxides in the presence of a complex metal cyanide complex catalyst, the starting compound having a plurality of active hydrogen atoms, the batch process comprising:

[0008] a) forming a starter mixture comprising the starting compound S 1 and the catalyst, and subsequently

[0009] b) continuously adding the alkylene oxides; and

[0010] c) optionally: continuously adding the starting compound S 2 ;

[0011] wherein

[0012] the starting compound S 1 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 10 g / mol to 500 g / mol;

[0013] the optional starting compound S 2 has an equivalent weight of 10 g / mol to 70 g / mol; and

[0014] No alkylene oxide is added in step a) or 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 preparing polyether polyol P has been added.

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

[0016] The present invention also relates to a method for preparing a polyurethane foam, which method 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 method.

[0017] Furthermore, the present invention relates to a polyurethane foam obtainable by the above method for preparing a polyurethane foam, and a molded article comprising the polyurethane foam obtainable or capable of being obtained by said method. 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 different said steps or components, they may also "consist essentially of" or "consist of" respectively the one or more of the different said steps or components.

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

[0020] In the case where upper and lower limits are cited for a property, a range of values defined by any combination of the upper limit and the lower limit is 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 a polyol can be measured by gel permeation chromatography (GPC) or vapor pressure osmometry (VPO).

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

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

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

[0025] The term "primary hydroxyl content" (or "PHC") as used herein refers to the relative proportion (in %) of primary hydroxyl groups in a polyether polyol 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" related to a polyether polyol refer to those portions of the 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. In addition, the contents are based on the total weight of alkylene oxides herein. The ethylene oxide content can be determined according to 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 produced in a reactor, but is produced in the reactor during a certain period of time, after which at least a part of the product is recovered, and then a new batch can be started.

[0028] In the present invention, the polyether polyol P has a hydroxyl value greater than 115 mg KOH / g, suitably greater than 120 mg KOH / g. The hydroxyl value of the polyether polyol P can be at least 120 mg KOH / g or at least 130 mg KOH / g or at least 140 mg KOH / g or at least 160 mg KOH / g or at least 180 mg KOH / g or at least 200 mg KOH / g or at least 220 mg KOH / g. In addition, the hydroxyl value of the polyether polyol P can be at most 500 mg KOH / g or at most 450 mg KOH / g or at most 400 mg KOH / g or at most 350 mg KOH / g or at most 300 mg KOH / g or at most 280 mg KOH / g.

[0029] In addition, in the present invention, the polyether polyol P contains ether bonds (or ether units). In addition, the polyether polyol may further contain ester bonds (or ester units) and / or carbonate bonds (or carbonate units). Preferably, the polyether polyol does not contain ester bonds (or ester units). In addition, preferably, the polyether polyol does not contain carbonate bonds (or carbonate units). Further, the polyether polyol can be composed of ether bonds.

[0030] In step a) of the present method, a starting compound S is formed1 and an initiator mixture of the composite metal cyanide complex catalyst. Step a) is carried out before step b) and optional step 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 resulting initiator mixture is charged into the reactor.

[0031] Thus, in the process of the present invention, a composite metal cyanide complex catalyst is used. The composite metal cyanide complex catalyst is also commonly referred to as a double metal cyanide (DMC) catalyst. The composite metal cyanide complex catalyst is generally represented by the following formula (1):

[0032] (1)M 1 a [M 2 b (CN) c d .e(M 1 f X g ).h(H 2 O).i(R)

[0033] wherein M 1 and M 2 are each a metal, X is a halogen atom, R is an organic ligand, and

[0034] 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, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, ethylene glycol monoter-butyl ether, isopropanol, and dioxane can be used as the organic ligand. The dioxane can be 1,4-dioxane or 1,3-dioxane, and is preferably 1,4-dioxane. Most preferably, the organic ligand or one of the organic ligands in the 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 starting compound S 1 satisfies one or both of the following two requirements (I) and (II):

[0038] (I) The starting compound S 1 has 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

[0039] (II) The starting compound S 1 has an equivalent weight of 10 g / mol to 500 g / mol.

[0040] Therefore, in the present invention, the compound S 1 can satisfy only requirement (I), or can satisfy only requirement (II), or can satisfy both requirements (I) and (II).

[0041] Under requirement (I), the starting compound S 1 has a hydroxyl value within 10% of the hydroxyl value of the polyether polyol P. This means that under requirement (I), the hydroxyl value of the starting compound S 1 differs from the hydroxyl value of the polyether polyol P by no more than 10%. Preferably, under requirement (I), the starting compound S 1 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 polyol P. Additionally, the hydroxyl value of the starting compound S 1 can be equal to the hydroxyl value of the polyether polyol P.

[0042] wherein a portion of the polyether polyol P prepared in a previous batch of the process according to the invention is used as the starting compound S in the next batch of the process according to the invention 1 and requirement (I) is met. Accordingly, the starting compound S 1 can comprise the same product as the final target product (polyether polyol 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 polyol P prepared in the previous batch can be used as the starting compound S in the next batch 1 . At the end of the batch process, a portion of the polyether polyol P thus prepared can remain in the reactor (commonly referred to as "bottoms") and can be used as the starting compound S in the next batch 1 . It is also possible to first store the polyether polyol P thus prepared in a separate storage container and then return a portion thereof to the reactor and use it as the starting compound S in the next batch 1 . Before step a) of the process, the above-mentioned "bottoms" can be pretreated, and such pretreatment can 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] In addition, in the present invention, the starting compound S 1 can comprise an intermediate polyether polyol that does not correspond to the polyether polyol P to be prepared according to the process of the invention. In particular, such an intermediate polyether polyol can be a polyether polyol prepared using a catalyst other than a complex metal cyanide complex catalyst (such as a potassium hydroxide (KOH) catalyst). When starting the first batch of the batch process, in the absence of the product from the previous batch, a portion thereof can be used as the starting compound S 1 , and before preparing the final polyether polyol product (polyether polyol P) using a complex metal cyanide complex catalyst, an intermediate polyether polyol product can first be prepared using such other catalyst. In cases where the starting compound S 1 comprises such an intermediate product, preferably step c) in which the starting compound S 2 is continuously added is not carried out. However, in cases where the starting compound S 1 does not comprise such an intermediate product, preferably step c) is carried out to prepare the polyether polyol P

[0044] Under requirement (II), the starting compound S 1 has an equivalent weight of from 10 g / mol to 500 g / mol. Under said requirement (II), the starting compound S 1may 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. Additionally, under the said requirement (II), the starting compound S 1 may have an equivalent weight of at most 500 g / mol or at most 450 g / mol or at most 400 g / mol or at most 350 g / mol or at most 300 g / mol or at most 280 g / mol or at most 250 g / mol.

[0045] The situation where only requirement (II) is satisfied but not requirement (I) is the case where another polyether polyol (another polyol grade) is prepared in the previous batch, and this another polyether polyol has a nominal functionality different from the nominal functionality of the desired polyether polyol P to be prepared in the next batch, and / or has a hydroxyl value that differs from the hydroxyl value of the polyether polyol P by more than 10%. When such a grade change is made, a part of the another polyether polyol prepared in the previous batch can be used as the starting compound S in the next batch 1 , where the polyether polyol P is prepared according to the method of the present invention. Therefore, the starting compound S 1 may contain products different from the final target product (polyether polyol 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 another polyether polyol prepared in the said previous batch can be used as the starting compound S in the said next batch 1 . At the end of the batch process, a part of the another polyether polyol thus prepared can remain in the reactor (commonly referred to as "bottom liquid") and be used as the starting compound S in the next batch for preparing the polyether polyol P 1 . It is also possible to first store the another polyether polyol thus prepared in a separate storage container, and then send a part of it back to the reactor and use it as the starting compound S in the next batch for preparing the polyether polyol P 1 . Before step a) of the present method, the above-mentioned "bottom liquid" can be pretreated, and such pretreatment can 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 catalysts (such as KOH) used in the previous batch.

[0046] Based on the total weight of the final product (polyether polyol P) in the reactor, the starting compound S used in step a) of the present method 1The amount can vary within a wide range. The proportion can be 1 wt% to 80 wt%, or 3 wt% to 70 wt%, or 5 wt% to 60 wt%, or 7 wt% to 50 wt%, or 8 wt% to 40 wt%. The 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 starting compound S 1 of the starting compound S.

[0047] Starting compound S 1 can consist of one starting compound that meets one or both of requirements (I) and (II). Alternatively, starting compound S 1 can consist of two or more starting compounds, suitably a mixture of two starting compounds, each of which meets one or both of requirements (I) and (II). In the latter case, for example, one of the starting compounds can meet requirements (I) and (II), while the other starting compound can only meet requirement (II). Additionally, in step a) of the present method, one or more starting compounds other than starting compound S 1 can be used to form the initiator mixture. Preferably, in the present invention, starting compounds that do not meet either of requirements (I) and (II) are not used in step a).

[0048] In step a) of the present method, in addition to the starting compound that meets requirement (I) (such as the above-mentioned "bottom liquid" containing the polyether polyol P prepared in the previous batch of the method according to the present invention), starting compounds having a hydroxyl value more than 10% higher than that of the polyether polyol P and having a relatively low equivalent weight, suitably in the range of 10 g / mol to 250 g / mol or 20 g / mol to 70 g / mol or 30 g / mol to 50 g / mol, can also be used in forming the initiator mixture. Such additional low-equivalent-weight starting compounds can have a functionality of 2 to 8 or preferably 2 to 3. Some suitable examples of such additional low-equivalent-weight starting compounds include diols and triols such as, for example, ethylene glycol, propylene glycol, butylene glycol, glycerol, water, trimethylolpropane, sorbitol, sucrose, and other low-equivalent-weight polyether polyols having an equivalent weight within one of the above ranges. Such additional low-equivalent-weight starting compounds are preferably used in a relatively small amount in step a), and based on the weight of the other starting compounds that meet requirement (I), this relatively small amount can be 0.1 wt% to 2.0 wt% or 0.25 wt% to 1.75 wt% or 0.5 wt% to 1.5 wt%. Advantageously, by adding such additional low-equivalent-weight starting compounds, the polydispersity and viscosity of the final polyether polyol P can be reduced.

[0049] In step a) of the present method, a starting mixture is formed which comprises a starting compound S 1 and a complex metal cyanide complex catalyst. In step a), the starting compound S 1 can be combined with the complex metal cyanide complex catalyst as described above, wherein the catalyst to be combined with the starting compound S 1 preferably comprises a fresh complex metal cyanide complex catalyst. In the present specification, a "fresh" catalyst means an unactivated catalyst which has not been used previously as a catalyst in a chemical process, specifically an unactivated catalyst which has not been exposed previously to an alkylene oxide. However, a fresh catalyst is suitable for use as a catalyst in a chemical process, which means that it is the final catalyst obtained as a product in a catalyst preparation process and not any intermediate catalyst or catalyst precursor. In the present specification, a "used" catalyst means a catalyst which has been used previously as a catalyst in a chemical process, specifically a catalyst which has been exposed previously to an alkylene oxide.

[0050] The above-mentioned fresh complex metal cyanide complex catalyst preferably used in step a) should be distinguished from any complex metal cyanide complex catalyst which may have been present in the starting compound S 1 before forming the starting mixture which comprises the starting compound S 1 and a complex metal cyanide complex catalyst (preferably comprising a fresh complex metal cyanide complex catalyst) in said step a). Any complex metal cyanide complex catalyst present in the starting compound S 1 before step a) may originate from a previous batch, wherein a complex metal cyanide complex catalyst was also used for preparing a polyether polyol, a part of which may subsequently be used as the starting compound S 1 in a next batch in which a polyether polyol P is prepared according to the method of the present invention. Thus, the starting compound S 1 may comprise a used complex metal cyanide complex catalyst. Furthermore, preferably, the starting compound S 1 does not comprise a fresh complex metal cyanide complex catalyst.

[0051] Thus, in the present invention, a polyether polyol P is prepared in the presence of a complex metal cyanide complex catalyst which comprises (i) a complex metal cyanide complex catalyst used in step a) for forming the starting mixture which comprises the starting compound S 1 and said catalyst, which catalyst (i) preferably comprises a fresh catalyst, and (ii) optionally a complex metal cyanide complex catalyst present in the starting compound S 1 before step a), which catalyst (ii) may comprise a used catalyst.

[0052] In the present invention, the starting compound S is added in step c). 2 In this case, step b) can be started before step c), or step b) and step c) can be started simultaneously, or step c) can be started before step b). In this case, preferably step b) is started before step c). In the present invention, the polyether polyol P is prepared in a reactor. However, as described above, step a) can be carried out inside the reactor, or alternatively, it can be carried out outside the reactor, and then the starting agent mixture thus obtained 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 optional step c) the starting compound S 2 is continuously added to the reactor.

[0053] Furthermore, in the present invention, no alkylene oxide is added in step a) or between step a) and step b). This means that in the present invention, the alkylene oxide is added only in step 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 polyol 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 polyol P has been added.

[0054] Advantageously, in the present invention, the double metal cyanide complex catalyst used in step a) as described above for forming the starting agent mixture comprising the starting compound S 1 and the catalyst and preferably comprising a fresh double metal cyanide complex catalyst (DMC catalyst) can be activated in step b) and preferably is not activated before step b). In particular, in the present invention, the catalyst can advantageously be activated in the early stage of step b), for example when 0.5 wt% to 10 wt% or 1 wt% to 5 wt% or 1.5 wt% to 3 wt% of the total amount of the continuously added alkylene oxide has been added. Thus, surprisingly, it appears that in the present invention it is advantageous not to require a method involving a separate DMC catalyst activation step, i.e. a method in which first a relatively small amount of alkylene oxide is added to the starting compound and the double metal cyanide complex catalyst, followed by a waiting period for activating the catalyst, and then alkylene oxide which can be further added.

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

[0056] The polyether polyol P prepared by the process of the present invention comprises a polyether chain which preferably contains a propylene oxide content, an optional butylene oxide content and an optional ethylene oxide content.

[0057] Preferably, the propylene oxide content of the polyether polyol P is at least 70% by weight, more preferably at least 80% by weight, more preferably at least 90% by weight, more preferably at least 95% by weight, most preferably at least 99% by weight. Further, preferably, the propylene oxide content of the polyether polyol P is at most 100% by weight.

[0058] The ethylene oxide content of the polyether polyol 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. Further, the ethylene oxide content of the polyether polyol P may be 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 polyol 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] Further, the polyether polyol P may contain primary hydroxyl groups. The primary hydroxyl group content of the polyether polyol P may be 0% or at least 1% or at least 3% or at least 5%. Further, the primary hydroxyl group content of the polyether polyol P may be at most 15% or at most 10% or at most 5%.

[0061] Further, the polyether polyol P may have a functionality of 2 to 6, 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 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 optional starting compound S 2 has an equivalent weight of from 10 g / mol to 70 g / mol. Preferably, the starting compound S 2 has an equivalent weight of from 10 g / mol to 60 g / mol, more preferably from 20 g / mol to 50 g / mol, more preferably from 25 g / mol to 40 g / mol, most preferably from 30 g / mol to 35 g / mol.

[0064] Further, preferably, the starting compound S 2 is a polyfunctional alcohol which usually contains 2 to 6 hydroxyl groups. Examples of such alcohols include diols, glycerol, pentaerythritol, trimethylolpropane, triethanolamine, sorbitol and mannitol. Advantageously, monopropylene glycol (MPG), glycerol or a combination of both can be used as the starting compound S2 Preferably, glycerol is used as the starting compound S 2 .

[0065] As described above, preferably, step b) starts before optional step c). Further preferably, optional step c) starts before 4 wt%, or 3 wt%, or 2 wt%, or 1 wt%, or 0.5 wt% of the total weight of the alkylene oxide required for preparing the polyether polyol P has been added in step b).

[0066] Preferably, at the start of step c), the addition rate of the starting compound S 2 is increased until the 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-mentioned target addition rates of the alkylene oxide and the starting compound S 2 have been reached, the weight ratio of the addition rate of the alkylene oxide to the addition rate of the starting compound S 2 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, wherein in the earlier stage, the weight ratio of the addition rate of the alkylene oxide to the addition rate of the starting compound S 2 can be from 8:1 to 30:1 or from 10:1 to 20:1.

[0068] In the present invention, preferably, optional step c) is stopped before step b) is stopped. In particular, preferably, once 30% to 99%, more preferably 50% to 99%, more preferably 60% to 97%, more preferably 70% to 95%, more preferably 80% to 93%, most preferably 85% to 93% of the total weight of the alkylene oxide required for preparing the polyether polyol P has been added in step b), optional step c) is stopped.

[0069] Furthermore, in the present invention, preferably, based on the sum of the total amount of the starting compound S 2 added in step c) and the total amount of the alkylene oxide added in step b), the total amount of the starting compound S 2 added in step c) is 5 wt% to 25 wt%, more preferably 6 wt% to 22 wt%, most preferably 10 wt% to 18 wt%.

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

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

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

[0073] In the above method for preparing a polyurethane foam, the polyether polyol is reacted with a polyisocyanate in the presence of a blowing agent.

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

[0075] The aromatic polyisocyanate may for example comprise 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 comprises toluene diisocyanate (TDI), i.e. non-polymeric TDI. TDI may be a mixture of 80 wt% 2,4-TDI and 20 wt% 2,6-TDI, which mixture is sold as "TDI-80".

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

[0077] Furthermore, the polyisocyanate may comprise any mixture of two or more of the above polyisocyanates. For example, the polyisocyanate may comprise a mixture of TDI and MDI, especially a mixture in which the weight ratio of TDI:MDI is from 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" means a blowing agent that can provide a foaming effect only after a chemical reaction with another compound. In the case where the blowing agent comprises a chemical blowing agent, the chemical blowing agent preferably comprises water. The 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 effects of fully chlorinated fluorinated alkanes (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 the so-called HCFCs) have no or less ozone-depleting effects and are thus preferred halogenated hydrocarbons for physically foaming 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 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 per hundred parts by weight of polyol (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 per hundred parts by weight of polyol (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 polyol (pphp), suitably 1 to 30 pphp, 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 this specification, "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 60 to 120. In particular, the isocyanate index can be at most 120, more suitably at most 110, more suitably at most 100, and most suitably 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 isocyanate-reactive groups.

[0088] Such "isocyanate-reactive groups" described above include, for example, OH groups from polyether polyols 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). Catalysts are typically used in an amount of 0.01 to 2.0 parts by weight (php) per one hundred parts by weight of polyether polyol. 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 one hundred parts by weight of polyether polyol (pphp). The preferred amount of 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 that can also be used to prepare polyurethane foams, especially flexible polyurethane foams, is diethanolamine, usually abbreviated as DEOA. The application rate of the crosslinking agent can be up to 2 parts by weight per one hundred parts by weight of polyol (pphp), but most suitably an amount in the range of 0.01 pphp to 0.5 pphp is 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 polyols, 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 polyether polyols, blowing agents, catalysts, and any other optional components other than polyisocyanates, and then adding polyisocyanates.

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

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

[0097] The present invention is further illustrated by the following examples.

[0098] Embodiment

[0099] Polyol A = a polyether polyol prepared by ring-opening polymerization of propylene oxide in the presence of glycerol and a double metal cyanide (DMC) catalyst: MW (molecular weight) = 673 g / mol; OH value = 250 mg KOH / g; functionality = 3.0; EW (equivalent weight) = 224 g / mol; DMC catalyst amount = 120 parts by weight per million parts by weight (ppmw).

[0100] In Table 1 below, for the reference example and Examples 1 to 3, the water content in glycerol and the following properties of the final polyether polyol are included: the amount of DMC catalyst (in the final polyol), OH value, and viscosity.

[0101] Reference Embodiment

[0102] 600 grams of polyol A and 0.288 grams of fresh DMC catalyst were charged into a reactor and mixed. The mixture was heated to 138 °C and a vacuum was applied to a level of 200 mbara for 60 minutes.

[0103] Then 29 grams of propylene oxide (PO) was charged to activate the catalyst, and a small amount of PO was continuously fed over 8 minutes. The pressure in the reactor increased to 0.59 bara and then steadily decreased, indicating that the catalyst was activated. Fifteen minutes after the start of the feeding of the small amount of PO, the continuous feeding of PO was resumed. Seven minutes after the resumption of the continuous PO feeding, the continuous feeding of glycerol containing 1,600 ppmw of water was started.

[0104] Eighteen minutes after the resumption of the continuous PO feeding and once 87% of the total amount of continuously fed PO had been fed, the continuous glycerol feeding was stopped. The total amount of PO continuously fed was 2,053 grams (excluding the initial 29 grams of PO). The total amount of glycerol continuously fed was 331 grams. After stopping the continuous glycerol feeding, 261 grams of PO was continuously fed over 32 minutes. After stopping the continuous PO feeding, i.e., 229 minutes after the start of the feeding of the initial 29 grams of PO, the PO was reacted for 30 minutes and then stripped for 30 minutes.

[0105] Embodiment 1

[0106] 600 grams of polyol A and 0.288 grams of fresh DMC catalyst were charged to the reactor and mixed. The mixture was heated to 138 °C and a vacuum was applied to a level of 200 mbara for 60 minutes.

[0107] Then the continuous feeding of PO was started. All the PO fed in this experiment was continuously fed without any interruption. Two minutes after the start of the continuous PO feeding, the continuous feeding of glycerol containing 1,600 ppmw of water was started. At the 2 minutes, 0.3% of the total amount of continuously added PO had been added. The initial glycerol feeding rate was 21 g / h (during the first 8 minutes) and then gradually increased to a final glycerol feeding rate of 110 g / h (during the last 176 minutes). The pressure in the reactor increased to 0.68 bara and once 45 g of PO had been continuously added in 5 minutes (which is 2% of the total amount of continuously added PO), the pressure decreased, indicating that the catalyst was activated.

[0108] After 194 minutes from the start of continuous PO feeding and once 91% of the total amount of continuously fed PO, which is 2,090 grams, has been fed, continuous glycerol feeding is stopped. The total amount of continuously fed glycerol is 328 grams. Based on the total amounts of continuously fed PO and glycerol, the total amount of continuously fed glycerol is 14% by weight. After stopping continuous glycerol feeding, 198 grams of PO are continuously fed within 21 minutes. After stopping continuous PO feeding 215 minutes after the start of continuous PO feeding, the PO is reacted for 30 minutes and then stripped for 30 minutes. Based on the total weight of the final product in the reactor, the amount of polyol A used is 20% by weight. Thus, the build ratio (the ratio of the total weight of the final product to the weight of polyol A) is 5.

[0109] When comparing the reference example and Example 1, both produce similar polyether polyol products, and this is also the case in terms of hydroxyl value and viscosity (as shown in Table 1). Thus, surprisingly and advantageously, in the batch polyether polyol production method in which both alkylene oxide and starting compound are continuously added, there is no need for a time-consuming separate initial DMC catalyst activation step, specifically, no such separate DMC catalyst activation step is required before the start of continuous feeding of the starting compound.

[0110] Embodiment 2

[0111] Example 2 is carried out in the same manner as Example 1, except that the amount of fresh DMC catalyst charged to the reactor is reduced from 0.288 grams to 0.230 grams.

[0112] As can be seen from Table 1 below, surprisingly and advantageously, it appears that in the batch polyether polyol production method in which both alkylene oxide and starting compound are continuously added and in which there is no separate initial DMC catalyst activation step, the amount of DMC catalyst to be used can be relatively low. In Example 2 in which a reduced amount of DMC catalyst is used, a polyether polyol can still be obtained, indicating that the catalyst is activated to a relatively large extent.

[0113] In addition, the hydroxyl value and viscosity of the polyether polyol product of Example 2 are surprisingly and advantageously similar to those of the polyether polyol product of Example 1, which was prepared in the same manner except that a higher amount of DMC catalyst was used.

[0114] Embodiment 3

[0115] Example 3 is carried out in the same manner as Example 1, except that the amount of water in glycerol is increased from 1,600 ppmw to 2,200 ppmw.

[0116] As can be seen from Table 1 below, surprisingly and advantageously, in a batch polyether polyol production process in which both the alkylene oxide and the starting compound are added continuously and in which there is no separate initial DMC catalyst activation step, the tolerance to water in the initiator feed is relatively high. In Example 3 in which glycerol with an increased water content was used, polyether polyols could still be obtained, indicating that the catalyst was not deactivated by such a high water content.

[0117] Furthermore, the hydroxyl value and viscosity of the polyether polyol product of Example 3 are surprisingly and advantageously similar to those of the polyether polyol product of Example 1, which was prepared in the same manner except that the glycerol used in Example 1 contained less water.

[0118] Table 1

[0119]

Claims

1. A batch process for preparing a polyether polyol P having a hydroxyl value greater than 115 mg KOH / g by reacting a starting compound S 1 and optionally a starting compound S 2 with one or more alkylene oxides in the presence of a double metal cyanide complex catalyst, the starting compound having a plurality of active hydrogen atoms, the batch process Comprising: a) Forming a starter mixture comprising the starting compound S 1 and the catalyst, and subsequently b) continuously adding an alkylene oxide; and c) Optionally: continuously add the starting compound S 2 ; wherein Starting compound S 1 having 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 500 g / mol; Optional starting compound S 2 having an equivalent weight of from 10 g / mol to 70 g / mol; and no alkylene oxide is added in step a) or between step a) and step b), and 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 polyol P has been added.

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

3. The method according to claim 1 or 2, wherein the starting compound S is added in step c) 2 .

4. The method according to claim 3, wherein step b) starts before step c).

5. The method according to claim 3 or 4, wherein step c) stops before step b) stops.

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.

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