Process for preparing polyurethane polymers

Abstract

The present invention relates to a process for preparing a polyurethane polymer, the process comprising the steps of: (a) providing a polyol composition comprising: (i) a polyol, (ii) a polyethyleneimine compound; and (iii) a bisulfite compound; (b) providing an isocyanate compound; (c) providing a catalyst; (d) combining and reacting the polyol composition, the isocyanate compound, and the catalyst to produce a polyurethane polymer.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 201680051590.8 (International Application No. PCT / US2016 / 053971), filed on September 27, 2016, entitled “Composition and Method for Reducing Residual Aldehyde Content and Malodor in Polyols”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to compositions and methods for reducing the residual aldehyde content and foulodor emitted by certain polyols. The application also describes the use of said polyols in the preparation of polyurethane polymers (e.g., polyurethane foams). Background Technology

[0003] Polyols are used in a variety of industrial processes. For example, polyols are a key raw material in the production of polyurethane polymers. Polyurethane polymers produced from polyols are used in a variety of applications, such as the production of polyurethane foams. These polyurethane foams are then used for many different end uses. For example, polyurethane foams are frequently used as padding and stuffing, such as in vehicle seats (e.g., car seats) and furniture (e.g., mattresses and other upholstered furniture). When these polyurethane foams are used in enclosed environments (e.g., the interiors of cars or other vehicles), the foams must typically pass tests that limit the amount of volatile organic compounds (VOCs) released by the foams. VOCs released by polyurethane foams during testing can be generated as byproducts of the polyurethane polymer production reaction. VOCs (e.g., aldehydes, such as formaldehyde, acetaldehyde, and propionaldehyde) are also present in the raw materials (e.g., polyols) used to manufacture the foams. These VOCs can also impart undesirable odors to the raw materials. For example, some commercially available polyols have high residual aldehyde content and a foul odor, both of which make them less attractive to polyurethane manufacturers. Therefore, it is desirable to find compositions or methods for reducing the detectable levels of volatile organic compounds present in these raw materials (such as polyols). This application aims to provide such compositions and methods. Summary of the Invention

[0004] In a first embodiment, the present invention provides a composition comprising:

[0005] (a) polyols; and

[0006] (b) Polyethyleneimine compounds.

[0007] In a second embodiment, the present invention provides a method for reducing the content of volatile aldehyde compounds in polyols, the method comprising the following steps:

[0008] (a) Provide a polyol containing a first amount of a volatile aldehyde compound;

[0009] (b) Provide polyethyleneimine compounds;

[0010] (c) The polyethyleneimine compound is added to the polyol to form a composition, wherein the composition contains a second amount of a volatile aldehyde compound, and the second amount of the volatile aldehyde compound is less than the first amount of the volatile aldehyde compound. Detailed Implementation

[0011] In a first embodiment, the present invention provides a composition comprising a polyol and a polyethyleneimine compound.

[0012] The composition may contain any suitable polyol. Suitable polyols include polyether polyols and polyester polyols. Preferably, the polyol is a polyether polyol. Suitable polyether polyols include those prepared by reacting epoxides (such as ethylene oxide, propylene oxide, butane oxide, and glycidyl) with a polyfunctional initiator compound (such as a polyfunctional alcohol or amine). Examples of suitable polyfunctional initiator compounds include, but are not limited to, water, glycerol, pentaerythritol, ethylene glycol, propylene glycol (e.g., 1,2-propanediol), trimethylolpropane, and ethylenediamine.

[0013] The polyol may have any suitable molar mass. In a preferred embodiment, the polyol has a molar mass of about 400 g / mol or greater. More preferably, the polyol has a molar mass of about 500 g / mol or greater, about 750 g / mol or greater, or about 1,000 g / mol or greater.

[0014] The polyols used in the preparation of the composition may contain volatile aldehyde compounds, such as formaldehyde, acetaldehyde, and propionaldehyde. While not wishing to be bound by any particular theory, it is believed that these volatile aldehyde compounds may be generated during the production of the polyol itself or due to oxidative degradation of the polyol during storage. Before the addition of the polyethyleneimine compound, the untreated polyol may contain up to 3 ppm or more of volatile aldehyde compounds (e.g., formaldehyde, acetaldehyde, and / or propionaldehyde) based on the weight of the polyol.

[0015] The composition may contain any suitable polyethyleneimine compound. The polyethyleneimine compound may be linear polyethyleneimine or branched polyethyleneimine. Preferably, the polyethyleneimine compound is branched polyethyleneimine. The polyethyleneimine may have any suitable degree of polymerization or molar mass. Preferably, the polyethyleneimine compound has a molar mass of about 500 g / mol or greater. More preferably, the polyethyleneimine compound has a molar mass of about 600 g / mol or greater, about 700 g / mol or greater, about 800 g / mol or greater, about 900 g / mol or greater, or about 1,000 g / mol or greater.

[0016] The polyethyleneimine compound may be present in the composition in any suitable amount. Based on the weight of the polyol present in the composition, the polyethyleneimine compound is preferably present in the composition in an amount of about 50 ppm or more. More preferably, based on the weight of the polyol present in the composition, the polyethyleneimine compound is present in the composition in an amount of about 75 ppm or more, about 100 ppm or more, about 125 ppm or more, about 150 ppm or more, about 175 ppm or more, about 200 ppm or more, about 300 ppm or more, about 400 ppm or more, or about 500 ppm or more. Based on the weight of the polyol present in the composition, the polyethyleneimine compound is preferably present in the composition in an amount of about 20,000 ppm or less, about 15,000 ppm or less, about 10,000 ppm or less, about 5,000 ppm or less, about 4,000 ppm or less, or about 3,000 ppm or less.Therefore, in a series of preferred embodiments, based on the weight of the polyol present in the composition, the polyethyleneimine compound is present in amounts from about 50 ppm to about 20,000 ppm (e.g., about 100 ppm to about 20,000 ppm, about 150 ppm to about 20,000 ppm, about 200 ppm to about 20,000 ppm, about 300 ppm to about 20,000 ppm, about 400 ppm to about 20,000 ppm, or about 500 ppm to about 20,000 ppm), from about 50 ppm to about 15,000 ppm (e.g., about 100 ppm to about 15,000 ppm). Approximately 150 ppm to approximately 15,000 ppm, approximately 200 ppm to approximately 15,000 ppm, approximately 300 ppm to approximately 15,000 ppm, approximately 400 ppm to approximately 15,000 ppm, or approximately 500 ppm to approximately 15,000 ppm, approximately 50 ppm to approximately 10,000 ppm (e.g., approximately 100 ppm to approximately 10,000 ppm, approximately 150 ppm to approximately 10,000 ppm, approximately 200 ppm to approximately 10,000 ppm, approximately 300 ppm to approximately 10,000 ppm, approximately 400 ppm to approximately 10,000 ppm). m, or about 500 ppm to about 10,000 ppm), about 50 ppm to about 5,000 ppm (e.g., about 100 ppm to about 5,000 ppm, about 150 ppm to about 5,000 ppm, about 200 ppm to about 5,000 ppm, about 300 ppm to about 5,000 ppm, about 400 ppm to about 5,000 ppm, or about 500 ppm to about 5,000 ppm), about 50 ppm to about 4,000 ppm (e.g., about 100 ppm to about 4,000 ppm, about 150 ppm to about 4,000 ppm, about 2 The amount present in the composition is from about 0.00 ppm to about 4,000 ppm, about 300 ppm to about 4,000 ppm, about 400 ppm to about 4,000 ppm, or about 500 ppm to about 4,000 ppm, or about 50 ppm to about 3,000 ppm (e.g., about 100 ppm to about 3,000 ppm, about 150 ppm to about 3,000 ppm, about 200 ppm to about 3,000 ppm, about 300 ppm to about 3,000 ppm, about 400 ppm to about 3,000 ppm, or about 500 ppm to about 3,000 ppm).

[0017] As described above, the purpose of adding the polyethyleneimine compound to the polyol is to reduce the volatile aldehyde compounds present in the polyol. For example, it has been observed that adding the polyethyleneimine compound in the aforementioned amount can reduce the volatile aldehyde compounds present in untreated polyols by up to 30% or even more. Therefore, in a preferred embodiment, the composition (i.e., a combination comprising a polyol and a polyethyleneimine compound) contains approximately 2 ppm or less of volatile aldehyde compounds based on the weight of the polyol. In addition to reducing the amount of volatile aldehyde compounds in the polyol, the addition of the polyethyleneimine compound has also been observed to reduce the malodor emitted by the polyol. The ability of the polyethyleneimine compound to reduce the measured amount of volatile aldehyde compounds and malodor in polyols is surprising and unexpected.

[0018] The composition may contain other components besides the polyol and polyethyleneimine compound. For example, the composition may contain a second amine compound. In a preferred embodiment, the composition also contains tert-butylamine (i.e., 2-methylpropyl-2-amine) as the second amine compound. When present in the composition, the second amine compound may be present in any suitable amount. If the second amine compound is present in the composition, it is preferably present in the composition at an amount of about 5 ppm or more, based on the weight of the polyol present in the composition. More preferably, based on the weight of the polyol present in the composition, the second amine compound is preferably present in the composition at an amount of about 10 ppm or more, about 15 ppm or more, about 20 ppm or more, or about 25 ppm or more.

[0019] In some potentially preferred embodiments, the composition contains a bisulfite compound in addition to the polyol and polyethyleneimine compound. In a preferred embodiment, the composition also contains sodium bisulfite. The bisulfite compound may be present in any suitable amount when present in the composition. Based on the weight of the polyol present in the composition, the bisulfite compound is preferably present in the composition in an amount of about 50 ppm or more. More preferably, based on the weight of the polyol present in the composition, the bisulfite compound is present in the composition in an amount of about 75 ppm or more, about 100 ppm or more, about 125 ppm or more, about 150 ppm or more, about 175 ppm or more, about 200 ppm or more, about 300 ppm or more, about 400 ppm or more, or about 500 ppm or more. Based on the weight of the polyol present in the composition, the bisulfite compound is preferably present in the composition in an amount of about 20,000 ppm or less, about 15,000 ppm or less, about 10,000 ppm or less, about 5,000 ppm or less, about 4,000 ppm or less, or about 3,000 ppm or less.Therefore, in a series of preferred embodiments, based on the weight of the polyol present in the composition, the bisulfite compound is present in amounts from about 50 ppm to about 20,000 ppm (e.g., about 100 ppm to about 20,000 ppm, about 150 ppm to about 20,000 ppm, about 200 ppm to about 20,000 ppm, about 300 ppm to about 20,000 ppm, about 400 ppm to about 20,000 ppm, or about 500 ppm to about 20,000 ppm), from about 50 ppm to about 15,000 ppm (e.g., about 100 ppm to about 15,000 ppm). Approximately 150 ppm to approximately 15,000 ppm, approximately 200 ppm to approximately 15,000 ppm, approximately 300 ppm to approximately 15,000 ppm, approximately 400 ppm to approximately 15,000 ppm, or approximately 500 ppm to approximately 15,000 ppm, approximately 50 ppm to approximately 10,000 ppm (e.g., approximately 100 ppm to approximately 10,000 ppm, approximately 150 ppm to approximately 10,000 ppm, approximately 200 ppm to approximately 10,000 ppm, approximately 300 ppm to approximately 10,000 ppm, approximately 400 ppm to approximately 10,000 ppm). m, or about 500 ppm to about 10,000 ppm), about 50 ppm to about 5,000 ppm (e.g., about 100 ppm to about 5,000 ppm, about 150 ppm to about 5,000 ppm, about 200 ppm to about 5,000 ppm, about 300 ppm to about 5,000 ppm, about 400 ppm to about 5,000 ppm, or about 500 ppm to about 5,000 ppm), about 50 ppm to about 4,000 ppm (e.g., about 100 ppm to about 4,000 ppm, about 150 ppm to about 4,000 ppm, about 2 The amount present in the composition is from about 0.00 ppm to about 4,000 ppm, about 300 ppm to about 4,000 ppm, about 400 ppm to about 4,000 ppm, or about 500 ppm to about 4,000 ppm, or about 50 ppm to about 3,000 ppm (e.g., about 100 ppm to about 3,000 ppm, about 150 ppm to about 3,000 ppm, about 200 ppm to about 3,000 ppm, about 300 ppm to about 3,000 ppm, about 400 ppm to about 3,000 ppm, or about 500 ppm to about 3,000 ppm).

[0020] When present in the composition, the amount of the bisulfite compound in the composition can also be expressed relative to the amount of the polyethyleneimine compound in the composition. Preferably, the bisulfite compound is present in the composition in an amount of about 0.5 parts by weight or more / 1 part of the polyethyleneimine compound. More preferably, the bisulfite compound is present in the composition in an amount of about 2 parts by weight or less / 1 part of the polyethyleneimine compound. Thus, in a more specific preferred embodiment, the bisulfite compound is present in the composition in an amount of about 0.5 to about 2 parts by weight / 1 part of the polyethyleneimine compound. In a particularly preferred embodiment, the bisulfite compound is present in the composition in an amount of about 2 parts by weight / 1 part of the polyethyleneimine compound.

[0021] As described above, the present invention also provides a method for reducing the amount of volatile aldehyde compounds present in a polyol. In one embodiment, the method includes the steps of: (a) providing a polyol; (b) providing a polyethyleneimine compound; and (c) adding the polyethyleneimine compound to the polyol to form a composition. The polyol contains a first amount of the volatile aldehyde compound, and the composition contains a second amount of the volatile aldehyde compound. The second amount of the volatile aldehyde compound is less than the first amount of the volatile aldehyde compound. In other words, the content of the volatile aldehyde compound in the polyol has been reduced by adding the polyethyleneimine compound. The polyol, polyethyleneimine compound, and other additional components used in this method may be any of the materials described above in relation to the first embodiment of the present invention.

[0022] As described above, the compositions of the present invention can be used in the production of polyurethane polymers. The compositions can be used alone as the sole source of a polyol, or they can be used in combination with one or more other polyols. The polyol or mixture of polyols used in the production of polyurethane polymers depends at least in part on the desired polymer properties. In the production of polyurethane polymers, the compositions can be used in combination with any suitable isocyanate compound or combination of isocyanate compounds. Suitable isocyanate compounds include, but are not limited to, toluene diisocyanate and diphenylmethane diisocyanate. Typically, one or more polyols and isocyanate compounds react in the presence of a catalyst—such as an amine catalyst, an organometallic catalyst (e.g., an organotin compound), or a mixture of both. Amine catalysts are typically tertiary amine compounds and are the most commonly used catalysts in the production of flexible polyurethane foams—such as those used in seating and other cushioning applications. Unfortunately, the use of amine catalysts can impart an unpleasant odor or foul smell to polyurethane polymers. Surprisingly, it has been observed that the polyethyleneimine compound contained in the compositions of the present invention can also reduce the foul smell imparted to the polymer by the use of amine catalysts.

[0023] The following examples further illustrate the subject matter described above, but should not be construed as limiting its scope in any way.

[0024] Example 1

[0025] This embodiment illustrates the production of the composition according to the present invention.

[0026] The initial acetaldehyde content in a commercially available polyol (sample 1A) was quantitatively determined. The odor of the polyol was also qualitatively measured by smelling a certain amount of the polyol in the container. The initial measurement results were recorded for subsequent comparison and are listed in Table 1 below.

[0027] Different amounts of polyethyleneimine compounds (with a molar mass of approximately 2,500 g / mol) were added to the polyols and stirred at room temperature (approximately 22°C) for about 1 hour. Sample 1J was heated to approximately 100°C and stirred for about 1 hour. Antioxidant blends (containing lactone-based antioxidants, phosphite-based antioxidants, and hindered phenolic antioxidants) were also added to samples 1C-1J. Tert-butylamine was also added to samples 1D-1G, and one drop of water was added to sample 1G. The acetaldehyde content and odor of the resulting compositions were then measured and recorded for comparison with the untreated polyol. These measurement results are listed in Table 1 below.

[0028] Table 1. Results of polyethyleneimine compound concentration (PEI), antioxidant concentration (AOX), tert-butylamine concentration (TBA), acetaldehyde content (CHO), and odor measurement for samples 1A-1J

[0029] Sample PEI (ppm) AOX (ppm) TBA (ppm) CHO (ppm) odor 1A -- -- -- 3.05 Extremely obvious 1B 520 -- -- 2.16 Not very obvious 1C 10,000 2,000 -- 1.62 Some things are worth noting 1D 10,000 2,000 30 1.18 Some things are worth noting 1E 500 2,000 30 1.74 Not very obvious 1F 200 2,000 30 1.68 Not very obvious 1G 200 2,000 30 1.63 Not very obvious 1H 200 2,000 -- 1.95 Not very obvious 1I 500 2,000 -- 2.01 Not very obvious 1J 100 2,000 -- 3.0 It's a little unclear

[0030] As shown in Table 1, each composition containing a polyethyleneimine compound (samples 1B-1J) exhibited a lower acetaldehyde concentration than the original, untreated polyol (sample 1A). These compositions also showed a noticeable improvement in odor compared to the original, untreated polyol. The reduction in acetaldehyde content and odor generally increased with increasing polyethyleneimine compound concentration. The addition of tert-butylamine reduced the measured acetaldehyde content in the polyols but did not have a noticeable effect on the odor of the polyols.

[0031] Example 2

[0032] This embodiment illustrates the production of the composition according to the present invention.

[0033] The odor of a commercially available polyol (sample 2A) was qualitatively measured by smelling a certain amount of polyol in the container. The initial measurement results were recorded for subsequent comparison and are listed in Table 2 below.

[0034] Different amounts of polyethyleneimine compound (with a molar mass of approximately 2,500 g / mol) were added to the polyol and stirred at room temperature (approximately 22°C) for about 1 hour. The odor of the resulting composition was then measured and recorded for comparison with the untreated polyol. These measurement results are listed in Table 2 below.

[0035] Table 2. Polyethyleneimine compound concentration (PEI) and odor measurement results of samples 2A-2C

[0036] Sample PEI (ppm) odor 2A -- Extremely obvious 2B 10,000 Some things are worth noting 2C 1,000 Not very obvious

[0037] As can be seen from the data in Table 2, each composition containing a polyethyleneimine compound (samples 2B and 2C) exhibited a noticeable improvement in odor compared to the original, untreated polyol (sample 2A). The degree of odor reduction generally increased with increasing polyethyleneimine compound concentration.

[0038] Example 3

[0039] This embodiment illustrates the production of the composition according to the present invention.

[0040] The initial acetaldehyde content of commercially available polyols (sample 3A) was quantitatively determined. The initial measurement results were recorded for subsequent comparisons and are listed in Table 3 below.

[0041] A polyethyleneimine compound (with a molar mass of approximately 2,500 g / mol) was added to the polyol, and the mixture was stirred at room temperature (approximately 22°C) for about 1 hour. The acetaldehyde content of the resulting composition (sample 3B) was then measured and recorded for comparison with the untreated polyol. The results are listed in Table 3 below.

[0042] Table 3. Polyethyleneimine compound concentration (PEI) and acetaldehyde content (CHO) of samples 3A and 3B

[0043] Sample PEI (ppm) CHO (ppm) 3A -- 6.02 3B 452 2.91

[0044] As can be seen from the data in Table 3, the composition containing polyethyleneimine compounds (sample 3B) exhibits a significantly lower acetaldehyde concentration than the original, untreated polyol (sample 3A).

[0045] Example 4

[0046] This embodiment illustrates the production of the composition according to the present invention.

[0047] TDI-MDI molded polyurethane foam was produced by mixing the components listed in Table 4 below. To produce this foam, sodium bisulfite / PEI (in the presence of PEI) was added to water, and the resulting mixture was added to a beaker containing a polyol. The resulting mixture was stirred at 4,000 rpm for approximately 30 seconds at ambient temperature. Next, the other components in Table 4 (except isocyanate (TM80)) were added to the beaker, and the mixture was stirred at 4,000 rpm for approximately 30 seconds at ambient temperature. Then, the isocyanate was added to the beaker, and the mixture was stirred again at 4,000 rpm for 5 to 10 seconds. The mixture was then cast in a mold maintained in a water bath at approximately 75°C. After approximately 5 minutes of curing, the mold was removed from the water bath, and the foam was removed from the mold.

[0048] Table 4. Foamed Plastic Formulations of Samples 4A to 4I

[0049]

[0050] Table 5. Additive content (expressed in ppm based on polyol content) and corresponding reduction in aldehyde content in samples 4A to 4I

[0051]

[0052]

[0053] As shown in Table 5, polyurethane foam containing sodium bisulfite exhibits a considerable reduction in both formaldehyde and acetaldehyde content. However, a comparison of the data for samples 4C to 4I reveals a dramatic increase in the observed reduction in acetaldehyde when polyethyleneimine is added to the formulation. This result is unexpected, considering that adding PEI alone does not produce a reduction in acetaldehyde content in the foam, or only a negligible reduction. In fact, this result indicates that the combination of polyethyleneimine and sodium bisulfite produces an unexpected synergistic effect.

[0054] Example 5

[0055] This embodiment illustrates the production of the composition according to the present invention.

[0056] MDI-molded polyurethane foam was produced by mixing the components listed in Table 6 below. To produce the foam, sodium bisulfite / PEI (in the presence of PEI) was added to water, and the resulting mixture was added to a beaker containing the polyol. The resulting mixture was stirred at 4,000 rpm for approximately 30 seconds at ambient temperature. Next, the other components in Table 6 (except isocyanate (PMDI)) were added to the beaker, and the mixture was stirred at 4,000 rpm for approximately 30 seconds at ambient temperature. Then, the isocyanate was added to the beaker, and the mixture was stirred again at 4,000 rpm for 5 to 10 seconds. The mixture was then cast in a mold maintained in a water bath at approximately 75°C. After approximately 5 minutes of curing, the mold was removed from the water bath, and the foam was removed from the mold.

[0057] Table 6. Foamed Plastic Formulations of Samples 6A to 6I

[0058]

[0059] Table 7. Additive content (expressed in ppm based on polyol content) and corresponding reduction in aldehyde content in samples 6A to 6I

[0060]

[0061]

[0062] As shown in Table 7, polyurethane foam containing sodium bisulfite exhibits a considerable reduction in both formaldehyde and acetaldehyde content. However, a comparison of data from samples 6C to 6I reveals that the observed reduction in acetaldehyde is even greater when polyethyleneimine is added to the formulation. This result is unexpected, considering that adding PEI alone does not produce a reduction in acetaldehyde content in the foam, or only a negligible reduction. In fact, this result indicates that the combination of polyethyleneimine and sodium bisulfite produces an unexpected synergistic effect.

[0063] All references cited in this article (including published texts, patent applications and patents) are incorporated herein by reference, as if each reference were explicitly included by reference.

[0064] Unless otherwise stated herein or clearly contradicted by the context, the expressions “a,” “an,” “the,” “the,” and similar references shall be interpreted to cover both singular and plural forms in describing the subject matter of this application, particularly in the appended claims. Unless otherwise stated, the terms “comprising,” “having,” “including,” and “containing” are interpreted as open-ended terms (i.e., meaning “including but not limited to”). Unless otherwise stated herein, the ranges of values ​​described herein are intended only as a way of abbreviating each individual value falling within that range, and each individual value is incorporated into this specification as if it were recited individually herein. Unless otherwise stated herein or clearly contradicted by the context, all methods described herein may be implemented in any suitable order. Unless otherwise claimed, the use of any and all instances or exemplary wording given herein (e.g., “for example” or “as”) is intended only to better elucidate the subject matter of this application and does not limit the scope of the subject matter. The wording in the specification should not be construed as indicating that any non-claim elements are necessary for practicing the subject matter described herein.

[0065] Preferred embodiments of the subject matter of this application are described herein, including the best methods known to the inventors for implementing the claimed subject matter. Variations of those preferred embodiments will be apparent to those skilled in the art upon reading the above description. The inventors believe that those skilled in the art may use such variations as appropriate, and that the inventors desire that the subject matter described herein be practiced in a manner different from that specifically described herein. Therefore, this disclosure includes all modifications and equivalents to the subject matter described in the appended claims permitted by applicable law. Furthermore, unless otherwise stated herein or otherwise clearly contradicted in the context, this disclosure covers any combination of the foregoing elements in all possible variations.

Claims

1. A method for preparing a polyurethane polymer, the method comprising the following steps: (a) Providing a polyol composition comprising: (i) Polyols, (ii) Polyethyleneimine compounds; and (iii) Bisulfite compounds; (b) Provide isocyanate compounds; (c) Provide a catalyst; (d) Combining the polyol composition, the isocyanate compound, and the catalyst, and reacting them to prepare a polyurethane polymer. The polyethyleneimine compound is present in the polyol composition at an amount of 50 ppm or more, based on the weight of the polyols present in the polyol composition. Based on the weight of the polyols present in the polyol composition, the bisulfite compound is present in the polyol composition in an amount of 50 ppm or more.

2. The method according to claim 1, wherein the polyol has a molar mass of 400 g / mol or greater.

3. The method according to claim 1, wherein the polyol is a polyether polyol.

4. The method according to claim 1, wherein the polyethyleneimine compound has a molar mass of 500 g / mol or greater.

5. The method of claim 1, wherein the polyethyleneimine compound is present in the polyol composition in an amount of 50 ppm to 3000 ppm based on the weight of the polyol present in the polyol composition.

6. The method of claim 1, wherein the bisulfite compound is present in the polyol composition in an amount of 50 ppm to 3000 ppm based on the weight of the polyol present in the polyol composition.

7. The method according to claim 1, wherein the bisulfite compound is sodium bisulfite.

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