Flexible polyurethane foam, method for producing same, and polyol composition for forming flexible polyurethane foam

Abstract

To provide a flexible polyurethane foam having compressive stress-strain characteristics capable of achieving both reduction of hardness at initial compression and suppression of a sense of wobble at high compression.SOLUTION: A ratio of a strain at 50% compression to a strain at 5% compression determined from a compressive stress-strain curve measured in a second compression operation in accordance with Method E described in JISK6400 2:2012 is 5.0 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a flexible polyurethane foam, a method for producing the same, and a polyol composition for forming the flexible polyurethane foam. [Background technology]

[0002] Flexible polyurethane foams are used in a variety of fields, including daily necessities, automotive materials, clothing, sports and leisure goods, medical materials, and civil engineering and construction materials. Among these applications, cushioning for automobile seats and wheelchairs, in addition to the traditional functions required of foams, requires reduced foam hardness during initial compression when sitting and a reduced wobbling sensation caused by the occupant's lower back or buttocks tilting sideways when driving around curves. Therefore, flexible polyurethane foams with a hardness distribution that is less likely to develop hardness during initial compression but more likely to develop hardness under high compression have been investigated to enable a more stable seating posture.

[0003] For example, Japanese Patent Laid-Open No. 2000-79037 (Patent Document 1) describes an automobile seat cushion pad that is comfortable to sit on due to its soft surface and does not cause fatigue even during long driving periods, in which at least a portion of the seating surface is made of high resilience foam, and which is calculated using the following formula using the "load at 25% strain" and "load at 3% strain" measured on the seating surface: "3% ISR" = "Load at 25% strain" / "Load at 3% strain" The present invention discloses a seat cushion pad for automobiles having a "3% ISR" value of 6 or more as calculated by the following method. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-79037 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even in an automobile seat cushion pad having a hardness distribution as described in Patent Document 1, it is not necessarily possible to sufficiently achieve both a reduction in hardness during initial compression and suppression of a wobbling feeling during high compression.

[0006] An object of one aspect of the present disclosure is to provide a flexible polyurethane foam having compressive stress-strain characteristics that can achieve both reduced hardness during initial compression and suppressed wobbling during high compression, and a method for producing the same. Another object of the present disclosure is to provide a polyol composition that contributes to the production of a flexible polyurethane foam having the above-mentioned compressive stress-strain characteristics. [Means for solving the problem]

[0007] The present disclosure provides the following aspects. [1] A flexible polyurethane foam in which the ratio of the stress at 50% compression to the stress at 5% compression, as determined from the compressive stress-strain curve measured in the second compression operation according to Method E described in JIS K6400-2:2012, is 5.0 or greater. [2] The flexible polyurethane foam according to [1], wherein the ratio of the stress at 50% compression to the stress at 5% compression is 15 or less. [3] The flexible polyurethane foam according to [1] or [2], wherein the stress at 50% compression is 300N / 200mmφ or more and 800N / 200mmφ or less. [4] The flexible polyurethane foam according to any one of [1] to [3], wherein the ratio of the stress at 25% compression to the stress at 5% compression obtained from the compressive stress-strain curve is 3.0 or more. [5] The flexible polyurethane foam according to [4], wherein the ratio of the stress at 25% compression to the stress at 5% compression is 6 or less. [6] The flexible polyurethane foam according to [4] or [5], wherein the stress at 25% compression is 180N / 200mmφ or more and 450N / 200mmφ or less. [7] A composition comprising a polyol compound, a catalyst, a crosslinking agent containing a carbohydrate, a foam stabilizer, and a foaming agent, The following formula (1): Foaming / resinization activity ratio=k2w / k1w (1) (In formula (1), k1w represents the resinification reaction rate constant per unit catalyst concentration, and k2w represents the foaming reaction rate constant per unit catalyst concentration.) A polyol composition for forming flexible polyurethane foams, having a foaming / resinification activity ratio represented by the following formula: [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to provide a flexible polyurethane foam having compressive stress-strain characteristics that can achieve both reduced hardness during initial compression and suppressed wobbling during high compression, and a method for producing the same. Furthermore, according to another aspect of the present disclosure, it is possible to provide a polyol composition that contributes to the production of a flexible polyurethane foam having the above-mentioned compressive stress-strain characteristics. DETAILED DESCRIPTION OF THE INVENTION

[0009] Exemplary embodiments for carrying out each aspect of the present disclosure will be described in further detail below, although the present disclosure is not limited to the following embodiments.

[0010] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. Furthermore, the upper and lower limit values ​​described individually can be combined in any way.

[0011] In this disclosure, "flexible polyurethane foam having compressive stress-strain characteristics that can achieve both reduced hardness at initial compression and suppressed wobbling sensation at high compression" refers to a flexible polyurethane foam whose compressive stress-strain curve exhibits linearity. In flexible polyurethane foams whose compressive stress-strain curve exhibits linearity, the compressive stress is smaller in the low compression ratio range than conventional flexible polyurethane foams, and therefore the hardness at initial compression is reduced. Furthermore, the compressive stress is larger in the high compression ratio range, and therefore the hardness at high compression is higher. Flexible polyurethane foams that exhibit high hardness at high compression suppress wobbling sensation and can hold occupants stably.

[0012] [Soft polyurethane foam] In one embodiment of the flexible polyurethane foam of the present disclosure, the ratio (50%SS / 5%SS) of the stress at 50% compression (50%SS) to the stress at 5% compression (5%SS), determined from a compression stress-strain curve measured in the second compression operation according to Method E of JIS K6400-2:2012, is 5.0 or greater. Flexible polyurethane foams with a 50%SS / 5%SS ratio equal to or greater than the lower limit exhibit a linear compression stress-strain curve, achieving both reduced hardness at initial compression and suppressed wobbling at high compression. From the viewpoints of further reducing hardness at initial compression and further suppressing wobbling at high compression, the 50%SS / 5%SS ratio is preferably 6.0 or greater, and more preferably 6.5 or greater.

[0013] When the compression stress-strain curve is a perfect straight line, 50% SS / 5% SS is 10, and the flexible polyurethane foam achieves both reduced hardness during initial compression and suppressed wobbling during high compression. Therefore, from the viewpoint of achieving a higher level of both reduced hardness during initial compression and suppressed wobbling during high compression, 50% SS / 5% SS is, for example, 15 or less, preferably 10 or less, and may be greater than 9.0 but not greater than 10. Furthermore, when 50% SS / 5% SS is 15 or less, the difference in hardness between the foam surface and the foam bottom is further reduced, further improving the sense of support from the foam when lateral sway occurs on curves. On the other hand, from the viewpoint of comfort, 50% SS / 5% SS may be 9.0 or less, or even 8.0 or less.

[0014] Furthermore, in flexible polyurethane foams, the ratio of the stress at 25% compression (25% SS) to the stress at 5% compression (5% SS) (25% SS / 5% SS) is preferably 3.0 or higher. Flexible polyurethane foams with a 25% SS / 5% SS ratio equal to or higher than the lower limit have a more improved linearity of the compression stress-strain curve, and achieve a better balance between reduced hardness at initial compression and suppressed wobbling at high compression. From the viewpoints of further reducing hardness at initial compression and further suppressing wobbling at high compression, 25% SS / 5% SS is more preferably 3.5 or higher, and even more preferably 3.7 or higher.

[0015] When the compression stress-strain curve is a perfect straight line, 25% SS / 5% SS is 5, and the flexible polyurethane foam achieves both reduced hardness at initial compression and suppressed wobbling at high compression. Therefore, from the viewpoint of achieving a higher level of both reduced hardness at initial compression and suppressed wobbling at high compression, 25% SS / 5% SS is, for example, 6 or less, preferably 5 or less, and may be greater than 4.8 but not more than 5. On the other hand, from the viewpoint of sitting comfort, 25% SS / 5% SS may be 4.8 or less, or may be 4.6 or less.

[0016] In flexible polyurethane foams, the stress at 50% compression (50% SS) is preferably 300 N / 200 mmφ or more and 800 N / 200 mmφ or less. Flexible polyurethane foams with a 50% SS equal to or greater than the lower limit mentioned above provide a better sense of support when sitting. Flexible polyurethane foams with a 50% SS equal to or less than the upper limit mentioned above provide a better sitting comfort when sitting. From the viewpoint of achieving both a sense of support and sitting comfort when sitting, the 50% SS is more preferably 350 N / 200 mmφ or more and 750 N / 200 mmφ or less, and even more preferably 400 N / 200 mmφ or more and 700 N / 200 mmφ or less.

[0017] Furthermore, in flexible polyurethane foams, the stress at 25% compression (25% SS) is preferably 180 N / 200 mmφ or more and 450 N / 200 mmφ or less. Flexible polyurethane foams with a 25% SS equal to or greater than the above-mentioned lower limit provide a better sense of support when sitting. Flexible polyurethane foams with a 25% SS equal to or less than the above-mentioned upper limit provide a better sitting comfort when sitting. From the viewpoint of achieving both a better sense of support and a better sitting comfort when sitting, the 25% SS is more preferably 200 N / 200 mmφ or more and 420 N / 200 mmφ or less, and even more preferably 210 N / 200 mmφ or more and 400 N / 200 mmφ or less.

[0018] [Polyol composition] A polyol composition according to another embodiment of the present disclosure is a polyol composition for forming a flexible polyurethane foam, and is preferably used to form the flexible polyurethane foam according to one embodiment of the present disclosure. The polyol composition contains a polyol compound, a catalyst, a crosslinking agent containing a saccharide, a foam stabilizer, and a blowing agent.

[0019] (Polyol compound) The polyol compound is not particularly limited as long as it is a polyol compound used in the production of flexible polyurethane foams, and examples thereof include polyether polyols, polyester polyols, and polymer polyols. These polyol compounds may be used alone or in combination of two or more.

[0020] Examples of polyether polyols include polypropylene ether polyol, polyethylene polypropylene ether polyol (polyoxyethylene polyoxypropylene polyol), polytetramethylene ether glycol (PTMG), and the like.

[0021] Examples of polyester polyols include polycondensation polyester polyols and lactone polyester polyols. Examples of polycondensation polyester polyols include polyester polyols that are copolymers of adipic acid and diols. Examples of lactone polyester polyols include polycaprolactone polyols.

[0022] The number average molecular weight of the polyol compound is preferably 3,500 or more and 10,000 or less, and more preferably 4,500 or more and 8,000 or less, from the viewpoint of easily obtaining a flexible polyurethane foam having sufficient flexibility and durability.

[0023] The nominal functionality of the polyol compound may be 2 or more from the viewpoint of improving the wet heat compression set, which is an index of durability. The nominal functionality of the polyol component may be 6 or less from the viewpoint of facilitating the production of a flexible polyurethane foam with sufficient flexibility. From these viewpoints, the nominal functionality is preferably 2 to 6, more preferably 2 to 4. When the polyol component contains multiple types of polyol compounds, it is preferable that the nominal functionality of at least one polyol compound is in the above range, and it is more preferable that the nominal functionality of all polyol compounds is in the above range. The nominal functionality refers to the theoretical average functionality (the number of active hydrogen atoms per molecule) assuming that no side reactions occur during the polymerization reaction of the polyol.

[0024] The polyol compound may contain a polyether polyol having a polyoxyalkylene chain containing oxyethylene units and oxypropylene units as structural units (for example, a polyoxyalkylene chain consisting of a copolymer of oxyethylene and oxypropylene) from the viewpoint of promoting cell breakage of a flexible polyurethane foam. The nominal number of functional groups of such a polyol is preferably 2 to 6, more preferably 2 to 4. Furthermore, from the viewpoint of storage stability at low temperatures, it is preferable that the oxyethylene units and oxypropylene units are randomly arranged (for example, a copolymer of oxyethylene and oxypropylene is a random copolymer). Furthermore, from the viewpoint of further improving durability, it is preferable to contain a polyether polyol containing oxyethylene units as the main structural unit. The content of oxyethylene units in the polyether polyol containing oxyethylene units as the main structural unit is more than 50% by mass, preferably 60 to 90% by mass, more preferably 60 to 85% by mass.

[0025] The content of the polyether polyol containing oxyethylene units as main structural units may be 0.1% by mass or more, based on the total amount of the polyol components, from the viewpoint of improving the moldability of the flexible polyurethane foam and making it easier to achieve the above-mentioned effect of improving durability. The content of the polyether polyol containing oxyethylene units as main structural units may be 5.0% by mass or less, based on the total amount of the polyol components, from the viewpoint of suppressing a decrease in elongation of the flexible polyurethane foam and making it easier to achieve the above-mentioned effect of improving durability. From these viewpoints, the content of the polyether polyol containing oxyethylene units as main structural units is preferably 0.1 to 5.0% by mass, based on the total amount of the polyol components.

[0026] Examples of polymer polyols include polymer polyols obtained by polymerizing vinyl monomers in the above-mentioned polyol compounds (excluding polymer polyols). The polymerization method for vinyl monomers is not particularly limited, and known polymerization methods such as radical polymerization can be employed. Examples of such polymer polyols include those obtained by polymerizing vinyl monomers in polyether polyols such as the above-mentioned polyethylene polypropylene polyols in the presence of a radical polymerization initiator, followed by stable dispersion. Examples of vinyl monomers include acrylonitrile, styrene, vinylidene chloride, hydroxyalkyl methacrylate, alkyl methacrylate, etc. Among these, acrylonitrile and styrene are preferred. Examples of such polymer polyols include EL-923 (trade name) manufactured by AGC Corporation and FA-728R (trade name) manufactured by Sanyo Chemical Industries, Ltd.

[0027] (catalyst) The catalyst is represented by the following formula (1): Foaming / resinization activity ratio=k2w / k1w (1) (In formula (1), k1w represents the resinification reaction rate constant per unit catalyst concentration, and k2w represents the foaming reaction rate constant per unit catalyst concentration.) The catalyst has a foaming / resinification activity ratio of 0.200 or less, as expressed by the formula (2). By using a catalyst having a foaming / resinification activity ratio of 0.200 or less, the compressive stress-strain curve exhibits linearity, and it becomes easier to obtain a flexible polyurethane foam that achieves both reduced hardness at initial compression and suppressed wobbling at high compression to a higher degree. From this perspective, the foaming / resinification activity ratio is preferably 0.200 or less, and more preferably 0.180 or less.

[0028] The foaming / resinification activity ratio is preferably 0.005 or more, more preferably 0.010 or more, from the viewpoint of promoting the foaming reaction to moderately progress and promoting the volume expansion of the resin by the generated carbon dioxide gas.

[0029] The resinification reaction rate constant k1w is a parameter calculated by the following method. Specifically, toluene diisocyanate and diethylene glycol are charged so that the molar ratio of isocyanate groups to hydroxyl groups is 1.0, a fixed amount of catalyst component (the object of calculation of k1w) is added, and the resinification reaction is carried out in a benzene solvent at a constant temperature, and the amount of unreacted isocyanate is measured. Here, assuming that the reaction between toluene diisocyanate and diethylene glycol is first-order with respect to the concentration of each, the following formula (I) is established. dx / dt=k(ax) 2 (I) [In formula (I), x is the concentration of reacted NCO groups (mol / L), a is the initial concentration of NCO groups (mol / L), k is the reaction rate constant (L / mol h), and t is the reaction time (h)]

[0030] Substituting the initial conditions t=0 and x=0 into equation (I) and integrating, the following equation (II) is obtained. 1 / (ax)=kt+1 / a (II) [In formula (II), k is the reaction rate constant (L / mol h) represented by the following formula (III)] k=ko+KcC (III) [In formula (III), k o is the reaction rate constant without catalyst (L / mol h), K c is the catalytic constant (L 2 / g mol h), C: catalyst concentration in the reaction system (g / L)

[0031] The reaction rate constant k in the resinification reaction is calculated from formula (II) and substituted into formula (III) to calculate the catalytic constant Kc in the resinification reaction.

[0032] The catalytic constant Kc obtained by the following formula (IV) is divided by the molecular weight (mc) of the catalyst to obtain the resinification reaction rate constant k1w (L) per unit catalyst concentration, which can be regarded as the activity per unit catalyst concentration. 2 / g·mol·h) Kc / mc=k1w (IV)

[0033] In addition, when the catalyst is a combination of n types (n≧2), the resinification reaction rate constant k1w(L2 / g·mol·h) can be calculated using the following formula (V):

[0034]

number

[0035] [In formula (V), k1w i : Resinification reaction rate constant (L) per unit catalyst concentration of catalyst i 2 / g·mol·h), W i : mass of catalyst i (g)

[0036] On the other hand, the foaming reaction rate constant k2w can be determined in the same manner as above by subjecting toluene diisocyanate and water to a foaming reaction in a benzene solvent under the same conditions as in the resinification reaction described above. That is, the reaction rate constant k in the foaming reaction is determined from equation (II) and substituted into equation (III) to determine the catalytic constant Kc in the foaming reaction. The determined catalytic constant Kc is divided by the molecular weight (mc) of the catalyst using the following equation (VI) to obtain the foaming reaction rate constant k2w (L) per unit catalyst concentration, which can be regarded as the activity per unit catalyst concentration. 2 / g·mol·h) Kc / mc=k2w (VI)

[0037] In addition, when the catalyst is a combination of n types (n≧2), the foaming reaction rate constant k2w(L 2 / g·mol·h) can be calculated using the following formula (VII):

[0038]

number

[0039] [In formula (VII), k2w i : The foaming reaction rate constant (L) per unit catalyst concentration of catalyst i 2 / g·mol·h), W i : mass of catalyst i (g)

[0040] Examples of catalysts having a foaming / resinification activity ratio of 0.200 or less include 2-hydroxymethyltriethylenediamine aqueous solution, triethylenediamine, 1,2-dimethylimidazole, N-ethylmorpholine, diazabicycloundecene, etc. These catalysts may be used alone or in combination of two or more.

[0041] Furthermore, even if a catalyst has a foaming / resinification activity ratio of more than 0.200, it can be used as a catalyst mixture having a foaming / resinification activity ratio of less than 0.200 by combining it with a catalyst having a foaming / resinification activity ratio of less than 0.200. Examples of catalysts having a foaming / resinification activity ratio of more than 0.200 include bis(dimethylaminoethyl)ether, 2-[{2-[2-(dimethylamino)ethoxy]ethyl}(methyl)amino]ethanol, triethylamine, and N,N-dimethyldecylamine. Specific examples of combinations of a catalyst having a foaming / resinification activity ratio of more than 0.200 and a catalyst having a foaming / resinification activity ratio of less than 0.200 include triethylenediamine and bis(dimethylaminoethyl)ether, 2-hydroxymethyltriethylenediamine and 2-[{2-[2-(dimethylamino)ethoxy]ethyl}(methyl)amino]ethanol, and 2-hydroxymethyltriethylenediamine and N,N-dimethyldecylamine.

[0042] The content of the catalyst is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the polyol compound, from the viewpoint of sufficient curing progress; and from the viewpoint of good moldability, the content is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, and even more preferably 3.0 parts by mass or less, relative to 100 parts by mass of the polyol compound.

[0043] (Crosslinking agent) The crosslinking agent preferably contains a saccharide. Use of a crosslinking agent containing a saccharide facilitates the production of a flexible polyurethane foam that exhibits a linear compressive stress-strain curve and achieves both reduced hardness at initial compression and reduced wobbling at high compression to a higher degree. Examples of saccharides include monosaccharides, disaccharides, oligosaccharides, polysaccharides, monosaccharide alcohols, disaccharide alcohols, and oligosaccharide alcohols. Monosaccharides are the smallest units of saccharides, and disaccharides and oligosaccharides are formed by dehydration condensation of two or 3 to 10 monosaccharides to form a glycosidic bond, resulting in a single molecule. Sugar alcohols are formed by reducing the carbonyl group of a saccharide. These saccharides may be used alone or in combination of two or more. Among these saccharides, monosaccharide alcohols, disaccharide alcohols, and oligosaccharide alcohols are preferred from the viewpoints of workability during preparation of the polyol composition and storage stability of the polyol composition.

[0044] (sugar alcohol) Examples of monosaccharide alcohols include tetriols such as erythritol and threitol; pentitols such as arabitol, xylitol, and ribitol; hexitols such as sorbitol, mannitol, and galactitol; heptitols such as volemitol; octitols such as D-erythro-D-galactoctitol; nonitols; and decitols. There are no limitations on the configuration of these monosaccharide alcohols, and they may be D- or L-isomers, or may be a DL-isomer, which is a mixture of D- and L-isomers. They may also be in a crystalline or liquid state, and may be hydrated or contain water.

[0045] Examples of disaccharide alcohols include maltitol, lactitol, and palatinit.

[0046] Oligosaccharide alcohols are sugar alcohols with three or more sugars, and for example, trisaccharide alcohols to decasaccharide alcohols (trisaccharide alcohols, tetrasaccharide alcohols, pentasaccharide alcohols, hexasaccharide alcohols, heptasaccharide alcohols, octasaccharide alcohols, nonasaccharide alcohols, and decasaccharide alcohols) are classified as oligosaccharide alcohols. Oligosaccharide alcohols are broadly classified into homooligosaccharide alcohols, which are formed by dehydration condensation of three or more molecules (e.g., 3 to 10 molecules) of one monosaccharide alcohol via a glycosidic bond, and heterooligosaccharide alcohols, which are formed by dehydration condensation of at least two types of monosaccharides and / or sugar alcohols (at least one of which is a sugar alcohol) with three or more molecules (e.g., 3 to 10 molecules) via a glycosidic bond.

[0047] Examples of oligosaccharide alcohols include maltotriitol, maltotetriitol, maltopentaitol, maltohexitol, etc. These oligosaccharide alcohols may have a cyclic structure and may be anhydrous or hydrated.

[0048] Furthermore, the sugar alcohol may be one in which some of the hydroxyl groups have been ether- or ester-modified (ether-modified or ester-modified) for the purpose of improving the mixability with other components constituting the polyol composition, etc. However, from the viewpoint of significantly obtaining the effects of one embodiment of the present disclosure, the modification rate of the hydroxyl groups is preferably 30 mol % or less (0 to 30 mol %) of the total hydroxyl groups.

[0049] These sugar alcohols may be used alone or in combination of two or more. The sugar alcohol preferably includes at least one selected from monosaccharide alcohols to decasaccharide alcohols, and more preferably includes at least one selected from monosaccharide alcohols to hexasaccharide alcohols.

[0050] The sugar alcohol is preferably used as a mixture that is liquid at room temperature with a hydrophilic polyol such as ethylene glycol, diethylene glycol, or glycerin and / or water. Furthermore, various reduced starch syrups (sugar alcohol mixtures) can also be used.

[0051] (Sugars) In the polyol composition, sugars such as monosaccharides, disaccharides, oligosaccharides and polysaccharides may be used as a crosslinking agent in place of or in combination with the sugar alcohol.

[0052] Examples of monosaccharides include trioses, tetroses such as erythrose and threolose, pentoses such as arabinose, ribose, lyxose, deoxyribose, and xylose, hexoses such as allose, altrose, glucose, mannose, gulose, idose, galactose, fructose, sorbose, fucose, rhamnose, talose, galacturonic acid, glucuronic acid, mannuronic acid, and glucosamine, heptose, octose, nonose, and decose. These monosaccharides may be aldoses or ketoses, or may be dialdoses, monosaccharides having multiple carbonyl groups, monosaccharides having methyl groups, monosaccharides having acyl groups (particularly, C2-C4 acyl groups such as acetyl groups), carbohydrates into which a carboxyl group has been introduced, lyosugars, aminosugars, deoxysugars, and the like. Dialdoses are sugar derivatives with aldehyde groups at both ends of the carbon chain, such as tetraacetylgalactohexodialdose, isohexodialdose, and xylopentodialdose. Monosaccharides with multiple carbonyl groups include aldoalkoketoses such as osone and onose. Monosaccharides with methyl groups include methyl sugars such as altromethylose. Monosaccharides with acyl groups include acetylated forms of the above-mentioned aldoses, such as acetylated forms of aldehyde glucose pentaacetyl compounds. Carbohydrates with a carboxyl group introduced include, for example, sugar acids or uronic acids.

[0053] The monosaccharide may also be a cyclic isomer in which a cyclic structure is formed by a hemiacetal bond. The monosaccharide does not necessarily have optical activity and may be any of D-, L-, or DL-isomers. The monosaccharide may also be in a crystalline or liquid state, and may be a hydrate or contain water.

[0054] Examples of disaccharides include trehalose, kojibiose, nigerose, maltose, isomaltose, sophorose, laminaribiose, cellobiose, gentiobiose, lactose, sucrose, palatinose, melibiose, rutinose, primeverose, turanose, etc. Examples of trehalose include α,α-trehalose, β,β-trehalose, α,β-trehalose, etc.

[0055] Oligosaccharides are sugars of three or more sugars, and for example, trisaccharides to decasaccharides (trisaccharides, tetrasaccharides, pentasaccharides, hexasaccharides, heptasaccharides, octasaccharides, nonasaccharides, and decasaccharides) are classified as oligosaccharides. Oligosaccharides are broadly classified into homooligosaccharides, which are formed by dehydration condensation of three or more molecules (e.g., 3 to 10 molecules) of one monosaccharide type via a glycosidic bond, and heterooligosaccharides, which are formed by dehydration condensation of at least two or more molecules (e.g., 3 to 10 molecules) of at least two or more monosaccharide types via a glycosidic bond. Oligosaccharides may be reduced (maltose type) or non-reduced (trehalose type).

[0056] Examples of trisaccharides include homooligosaccharides such as maltotriose, isomaltotriose, panose, and cellotriose; and heterooligosaccharides such as manninotriose, solatriose, melezitose, planteose, gentianose, umbelliferose, lactosucrose, and raffinose.

[0057] Examples of tetrasaccharides include homooligosaccharides such as maltotetraose and isomaltotetraose; and heterooligosaccharides such as stachyose, cellotetraose, scorodose, lyquinose, and telolaose in which a sugar or sugar alcohol is bound to the reducing end of panose.

[0058] Examples of pentasaccharides include homooligosaccharides such as maltopentaose and isomaltopentaose; and heterooligosaccharides such as pentaose in which a disaccharide is bound to the reducing end of panose.

[0059] Examples of hexasaccharides include homooligosaccharides such as maltohexaose and isomaltohexaose.

[0060] These oligosaccharides may have a cyclic structure and may be anhydrous or hydrated. Examples of cyclic oligosaccharides include α-cyclodextrin (hexasaccharide), β-cyclodextrin (heptasaccharide), and γ-cyclodextrin (octasaccharide).

[0061] Furthermore, the monosaccharides, disaccharides, and oligosaccharides may have some of their hydroxyl groups ether- or ester-modified (ether-modified or ester-modified) for the purpose of improving the mixability with other components constituting the polyol composition, etc. However, from the viewpoint of significantly obtaining the effects of one embodiment of the present disclosure, the modification rate of hydroxyl groups is preferably 30 mol % or less (0 to 30 mol %) of all hydroxyl groups.

[0062] Examples of polysaccharides include amylose, amylopectin, glycogen, cellulose, agar, inulin, glucomannan, glycosaminoglycan (mucopolysaccharide), alginic acid, hyaluronic acid, chondroitin acid, heparin, and chitin.

[0063] These sugars may be used alone or in combination of two or more. The sugar preferably includes at least one selected from monosaccharides to decasaccharides, and more preferably includes at least one selected from monosaccharides to hexasaccharides.

[0064] The sugars are preferably used as a room temperature liquid mixture with a hydrophilic polyol such as ethylene glycol, diethylene glycol, or glycerin and / or water. From the viewpoints of workability during preparation of the polyol composition and storage stability of the polyol composition, the monosaccharides, disaccharides, and oligosaccharides are preferably isomerized liquid sugars, which are room temperature liquid mixtures such as high fructose liquid sugar, high fructose glucose liquid sugar, and glucose fructose liquid sugar.

[0065] (Carbohydrates) The carbohydrate contains at least one selected from the group consisting of such sugar alcohols and sugars, and it is particularly preferable that the carbohydrate contains a monosaccharide alcohol from the viewpoint of better storage stability (for example, storage stability in an environment where the polyol composition is exposed to temperatures significantly above room temperature for a long period of time, such as when transporting the polyol composition by ship). Furthermore, from the viewpoint of significantly obtaining such effects, the content of the monosaccharide alcohol is preferably 90% by mass or more, more preferably 95% by mass or more, based on the total amount of carbohydrates. Furthermore, the content of the monosaccharide alcohol may be 100% by mass based on the total amount of carbohydrates. That is, the content of the monosaccharide alcohol may be 90 to 100% by mass or 95 to 100% by mass based on the total amount of carbohydrates.

[0066] The number average molecular weight of the saccharide is preferably 120 or more, more preferably 180 or more, from the viewpoint that the compressive stress-strain curve of the flexible polyurethane foam tends to exhibit linearity, and is preferably 2500 or less, more preferably 2100 or less, and even more preferably 1800 or less, from the viewpoint that the moldability and elongation of the flexible polyurethane foam are improved. The number average molecular weight of the saccharide can be measured, for example, by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene.

[0067] The content of the carbohydrate is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and may be 0.6 parts by mass or more, 1.0 parts by mass or more, 1.5 parts by mass or more, 2.0 parts by mass or more, 3.0 parts by mass or more, or 4.0 parts by mass or more, per 100 parts by mass of the polyol compound, from the viewpoint that a flexible polyurethane foam having a linear compression stress-strain curve and which combines reduced hardness at initial compression with suppressed wobbling at high compression is easily obtained; and from the viewpoint that the moldability and elongation of the flexible polyurethane foam are improved, the content is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and may be 3.0 parts by mass or less, or 2.0 parts by mass or less, per 100 parts by mass of the polyol compound.

[0068] (Other crosslinking agents) From the viewpoint of improving the physical properties of the flexible polyurethane foam, such as the elongation percentage and the wet heat compression set, it is preferable that the polyol composition contains at least one cyclic glycol selected from the group consisting of alicyclic glycols and aromatic glycols as a crosslinking agent other than the saccharide.

[0069] Examples of alicyclic glycols include cyclohexanediol, cyclohexanedimethanol, and bisphenol A hydride. Examples of aromatic glycols include hydroquinone bis(2-hydroxyethyl) ether, dihydroxydiphenylmethane, polyoxyethylene bisphenol ether, and polyoxypropylene bisphenol ether. These cyclic glycols may be used alone or in combination of two or more. Among these cyclic glycols, 1,4-cyclohexanedimethanol and polyoxyethylene bisphenol A ether are preferred from the viewpoint of their high effect of improving the wet heat compression set of the resulting flexible polyurethane foam.

[0070] The content of the cyclic glycol is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the polyol compound, from the viewpoint of improving the physical properties of the resulting flexible polyurethane foam, such as the elongation percentage and wet heat compression set. Furthermore, from the viewpoint of easily adjusting the 25% compression hardness of the resulting flexible polyurethane foam to a desired range, the content of the cyclic glycol is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, and even more preferably 4.0 parts by mass or less, per 100 parts by mass of the polyol compound. From these viewpoints, the content of the cyclic glycol may be 0.5 to 8.0 parts by mass, 1.0 to 8.0 parts by mass, 1.5 to 8.0 parts by mass, 1.5 to 6.0 parts by mass, or 1.5 to 4.0 parts by mass.

[0071] The content of the saccharide-containing crosslinking agent is preferably 0.1 to 7.0 parts by mass per 100 parts by mass of the polyol compound, from the viewpoint that a compressive stress-strain curve exhibits linearity, a reduction in hardness at initial compression and a suppression of wobbling at high compression are further enhanced, and a flexible polyurethane foam with good moldability is more easily obtained. Also, from such a viewpoint, the content of the saccharide-containing crosslinking agent may be 1.0 part by mass or more, or 2.0 parts by mass or more, and may be 5.0 parts by mass or less, or 3.0 parts by mass or less, per 100 parts by mass of the polyol compound.

[0072] (Foam stabilizer) The foam stabilizer is not particularly limited as long as it is a foam stabilizer used in the production of flexible polyurethane foam, and examples thereof include surfactants, with organosilicon (e.g., silicone) surfactants being preferred. Specific foam stabilizers include SZ-1327, SZ-1325, SZ-1336, SZ-3601, and VORASURF TF1348 manufactured by Dow-Toray Industries, Inc., Y-10366 and L-5309 manufactured by Momentive, B-8724LF2 and B-8715LF2 manufactured by Evonik, and BL-1107LO manufactured by Menhover. These foam stabilizers may be used alone or in combination of two or more.

[0073] The content of the foam stabilizer is preferably 0.1 to 3.0 parts by mass, and more preferably 0.3 to 2.0 parts by mass, per 100 parts by mass of the polyol compound. When the content of the foam stabilizer is above the lower limit, the cells tend to be uniform, whereas when it is below the upper limit, a flexible polyurethane foam with good physical properties tends to be obtained.

[0074] (foaming agent) The blowing agent is not particularly limited as long as it is a blowing agent used in the production of flexible polyurethane foams, and examples thereof include water. Water reacts with isocyanate groups to form high-hardness urea groups and generate carbon dioxide gas, which can foam the mixed liquid of the polyol composition and the polyisocyanate composition. The content of water relative to the total amount of blowing agents is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and may be 100% by mass.

[0075] When the water content relative to the total amount of the blowing agent is less than 100% by mass, other blowing agents may be used in addition to water. Examples of such other blowing agents include low-boiling organic compounds such as cyclopentane and isopentane. Alternatively, a gas loading device may be used to mix and dissolve air, nitrogen gas, liquefied carbon dioxide, or the like into a mixture of a polyol composition and a polyisocyanate composition to foam the mixture.

[0076] The total content of the blowing agent is preferably 0.5 to 10 parts by mass, and more preferably 1.0 to 5.0 parts by mass, per 100 parts by mass of the polyol compound. When the total content of the blowing agent is equal to or greater than the lower limit, a low-density foam is likely to be obtained, whereas when the total content is equal to or less than the upper limit, stable foaming is likely to be obtained.

[0077] The polyol composition may further contain, as necessary, various known additives and auxiliaries such as an antioxidant, a filler, a flame retardant, a plasticizer, a colorant, and an antifungal agent, in addition to the polyol compound, catalyst, saccharide-containing crosslinking agent, foam stabilizer, and foaming agent.

[0078] [Method for producing flexible polyurethane foam] A method for producing a flexible polyurethane foam according to one embodiment of the present disclosure is a method for producing a flexible polyurethane foam by injecting a mixed solution of the polyol composition and the polyisocyanate composition according to another embodiment of the present disclosure into a mold set at 60°C or higher, and reacting and foaming the polyol compound and the polyisocyanate compound. In such a method for producing a flexible polyurethane foam, it is preferable to inject the mixed solution into a mold set at 65°C or higher.

[0079] (Polyisocyanate composition) The polyisocyanate composition contains a polyisocyanate compound, such as diphenylmethane diisocyanates (MDI) such as 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), and 2,2'-diphenylmethane diisocyanate (2,2'-MDI), polyphenylene polymethylene polyisocyanate (P-MDI), 2,4-tolylene diisocyanate (2,4-TDI), and 2,6-tolylene diisocyanate (2,6-TDI), as well as urethane-, urea-, allophanate-, nurate-, and biuret-modified versions of these compounds, and mixtures thereof.

[0080] In addition to the polyisocyanate compound, the polyisocyanate composition may further contain, as necessary, various known additives and auxiliaries such as antioxidants, fillers, flame retardants, plasticizers, colorants, and antifungal agents.

[0081] The polyol composition and the polyisocyanate composition are preferably mixed so that the NCO index (NCO / OH × 100) is within the range of 70 to 140. When the NCO index is equal to or greater than the lower limit, the durability and closed cell properties of the flexible polyurethane foam tend to be good, while when the NCO index is equal to or less than the upper limit, the foam collapse during foaming due to the extension of the molding cycle caused by the prolonged presence of unreacted isocyanate compound and the delay in the polymerization tends to be further suppressed. From this viewpoint, the NCO index is more preferably 70 to 120.

[0082] The method for mixing the polyol composition and the polyisocyanate composition is not particularly limited, and any mixing method used in known methods for producing flexible polyurethane foams can be used. The mixed solution of the polyol composition and the polyisocyanate composition prepared in this manner is preferably poured into a mold immediately after mixing.

[0083] In one embodiment of the method for producing a flexible polyurethane foam according to the present disclosure, a mixed solution of a polyol composition and a polyisocyanate composition is poured into a mold set at 60°C or higher, preferably 65°C or higher. This improves the linearity of the compression stress-strain curve of the resulting flexible polyurethane foam, making it easier to obtain a flexible polyurethane foam that achieves both reduced hardness at initial compression and reduced wobbling at high compression to a higher degree. From this perspective, the mold temperature is preferably set at 68°C or higher, and even more preferably at 70°C or higher. Furthermore, from the viewpoints of facilitating the gradual progress of the reaction between the polyol compound and the polyisocyanate compound and the reaction between water (the blowing agent) and the isocyanate compound, and thus suppressing collapse of the flexible polyurethane foam, the mold temperature is preferably set at 85°C or lower, more preferably 83°C or lower, and even more preferably 80°C.

[0084] The reaction time for reacting and foaming the polyol compound and the polyisocyanate compound is preferably 10 minutes or less, more preferably 7 minutes or less.

[0085] The flexible polyurethane foam produced in this manner exhibits a linear compression stress-strain curve, and achieves a high level of both reduced hardness at initial compression and suppression of wobbling at high compression.

[0086] While the reason why a flexible polyurethane foam exhibiting a linear compression stress-strain curve can be obtained by the flexible polyurethane foam production method according to one embodiment of the present disclosure is not entirely clear, the present inventors speculate as follows. Specifically, in the flexible polyurethane foam production method according to one embodiment of the present disclosure, a saccharide is used as the crosslinking agent, a catalyst with a low foaming / resinization activity ratio is used, and a mixed solution of a polyol composition and a polyisocyanate composition is poured into a mold set at 65°C or higher. Because the saccharide (particularly the sugar alcohol) forms an association state with water, which serves as the blowing agent, through hydrogen bonding, this association state is maintained in the early stages of the reaction, suppressing the urea reaction between water and isocyanate groups. Because the volume expansion of the foam due to foaming is small in the early stages of the reaction, the reaction occurs primarily on the underside of the mold (the surface that will become the front side of the foam). Therefore, the concentration of high-hardness urea bonds near the surface of the resulting flexible polyurethane foam is low, resulting in the formation of a foam with a relatively low hardness. As the reaction progresses, the associated water gradually dissociates from the carbohydrates (particularly sugar alcohols) due to the generated reaction heat and reacts with the isocyanate groups to form high-hardness urea bonds. As the reaction progresses, the foam expands in volume due to foaming, and the amount of urea bonds formed gradually increases from the bottom to the top of the mold (the surface that becomes the back of the foam). Therefore, the hardness of the resulting flexible polyurethane foam increases from the front to the back of the foam. Flexible polyurethane foams with low hardness on the surface and high hardness on the interior and back have reduced compressive stress in the low-compression range and increased compressive stress in the high-compression range. This is thought to result in a more linear compressive stress-strain curve for the resulting flexible polyurethane foam. Furthermore, when a catalyst with a low foaming / resinification activity ratio is used as the catalyst, resinification (urethanization) is promoted compared to the urea formation reaction in the early stage of the reaction, so that the concentration of low-hardness urethane bonds near the surface of the resulting flexible polyurethane foam increases, forming a flexible polyurethane foam with an even lower surface hardness, and further reducing the compressive stress in the low compression range. As a result, it is believed that the linearity of the compressive stress-strain curve of the resulting flexible polyurethane foam is further improved.Furthermore, when a mixed solution of a polyol composition and a polyisocyanate composition is poured into a mold set at 65°C or higher, the urethane reaction is accelerated compared to the urea reaction in the early stage of the reaction, and therefore the concentration of low-hardness urethane bonds near the surface of the resulting flexible polyurethane foam is further increased, forming a flexible polyurethane foam with an even lower surface hardness and further reducing the compressive stress in the low compression range. As a result, it is believed that the linearity of the compressive stress-strain curve of the resulting flexible polyurethane foam is further improved. [Example]

[0087] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0088] The raw materials used in each of the examples and comparative examples are as follows. (1) Polyol compounds PPG1: Polypropylene glycol (nominal functionality = 3, number average molecular weight = 6700, average content of ethylene oxide units = 14 mass%, primary terminal ratio = 85%, degree of unsaturation = 0.03 meq / g). PPG2: Polyoxyethylene polyoxypropylene polyol (AGC "Exenol EL-838"). PPG3: Polyoxyethylene polyoxypropylene polyol (Sanyo Chemical Industries, Ltd. "Sannyx FA-159"). POP: Polymer polyol (nominal functionality: 3, number average molecular weight: 5100, average content of ethylene oxide units: 14% by mass, primary terminal ratio: 78% by mass, polymer solid content: 25% by mass). (2) Crosslinking agent Sorb S: Sugar alcohol ("Sorbitol S" manufactured by Bussan Food Science Co., Ltd.). ·DEA: Diethanolamine (Mitsui Chemicals). (3) Catalyst RZETA-50W: 2-hydroxymethyltriethylenediamine aqueous solution (Tosoh Corporation "RZETA-50W", k1w = 0.399 L) 2 / g·mol·h, k2w=0.058L 2 / g·mol·h, foaming / resinizing activity ratio: 0.145). RX-10: N,N,N'-trimethyl-N'-hydroxyethyl-bisaminoethyl ether (Tosoh Corporation "TOYOCAT RX-10", k1w = 0.344 L) 2 / g·mol·h, k2w=1.047L 2 / g·mol·h, foaming / resinizing activity ratio: 3.040). TEDA-L33: Triethylenediamine dipropylene glycol solution ("TEDA-L33" manufactured by Tosoh Corporation, amine concentration: 33% by mass, k1w = 0.363 L) 2 / g·mol·h, k2w=0.048L 2 / g·mol·h, foaming / resinizing activity ratio: 0.132). ET: Bis(2-dimethylaminoethyl) ether (TOYOCAT ET, manufactured by Tosoh Corporation, k1w = 0.209 L) 2 / g·mol·h, k2w=0.819L 2 / g·mol·h, foaming / resinizing activity ratio: 3.918). (4) Foam stabilizer BL1107LO: Silicone foam stabilizer (MENHOVER "BL-1107LO"). TF1348: Silicone foam stabilizer (VORASURF TF1348 manufactured by Dow-Toray). (5) Foaming agent ·water. (6) Isocyanate compounds NCO1: Diphenylmethane diisocyanate (modified with polyethylene glycol (molecular weight: 1000), NCO group content: 31.7% by mass). NCO2: Polyphenylene polymethylene polyisocyanate (polymeric MDI, NCO group content: 33.1% by mass). ·NCO3: Polyphenylene polymethylene polyisocyanate (polymeric MDI, NCO group content: 32.4% by mass). NCO4: Diphenylmethane diisocyanate (polypropylene glycol (molecular weight: 4000, ethylene oxide content: 0 mass%, f=2) modified, NCO group content: 29.5 mass%). NCO5: A mixture of polymeric MDI (NCO group content: 30.5-32.0% by mass) and polypropylene glycol (molecular weight: 5000) modified tolylene diisocyanate (T-80) (mass ratio: MR-200 / modified T-80 = 90 / 10).

[0089] <Foaming / resinization activity ratio> The foaming / resinification activity ratio of each catalyst used in each example and comparative example was calculated using the foaming reaction rate constant k2w per unit catalyst concentration and the resinification reaction rate constant k1w per unit catalyst concentration, which were calculated using the above-mentioned formulas (I) to (VII), and calculated using the following formula (1): Foaming / resinization activity ratio=k2w / k1w (1) The foaming / resining activity ratio was calculated by the following formula.

[0090] Example 1 First, the inside of a reactor equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer was replaced with nitrogen, and then 70.0 g of PPG1, 1.6 g of PPG3, 30.0 g of POP, 1.2 g of Sorc S, 1.5 g of RZETA-50W, 1.0 g of BL-1107LO, and 1.5 g of water were charged into the reactor and stirred at 23°C for 0.5 hours to obtain a polyol composition.

[0091] The obtained polyol composition and NCO1 were each adjusted to 24 to 26°C. NCO1 was added to the polyol composition so that the NCO index (NCO / OH x 100) was 95, and the mixture was stirred using a mixer at 7000 rpm for 7 seconds. The obtained mixture was poured into a mold (300 mm x 300 mm x 100 mm) set to 70°C, and the mixture was reactively foamed for 5 minutes to obtain a flexible polyurethane foam.

[0092] (Examples 2 to 11 and Comparative Examples 1 to 6) A polyol composition was prepared in the same manner as in Example 1, except that the formulation was changed to the formulation shown in Tables 1 and 2. Furthermore, a flexible polyurethane foam was obtained in the same manner as in Example 1, except that the isocyanate compound was changed to the isocyanate compound shown in Tables 1 and 2 and the mold was set to the temperature shown in Tables 1 and 2.

[0093] <Total density> The total density (apparent density) of the obtained flexible polyurethane foam was measured according to the method described in JIS K7222: 2005. The results are shown in Tables 1 and 2.

[0094] <25% compression hardness> The 25% compression hardness (25% ILD, unit: N / 200mmφ) of the obtained flexible polyurethane foam (300mm length × 300mm width × 100mm thickness) was measured by the D method using a pressure plate with a diameter of 200mmφ in accordance with the method described in JIS K6400-2:2012. The results are shown in Tables 1 and 2.

[0095] <Compressive stress-strain characteristics> According to Method E of JIS K6400-2:2012, the resulting flexible polyurethane foam (300 mm length × 300 mm width × 100 mm thickness) was compressed twice using a 200 mm diameter pressure plate, and the compression stress-strain curve for the second compression was obtained. From the obtained compression stress-strain curve, the stresses (unit: N / 200 mm diameter) at 5%, 25%, and 50% compression were determined, and the ratio of the stress at 50% compression to the stress at 5% compression (50%SS / 5%SS) and the ratio of the stress at 25% compression to the stress at 5% compression (25%SS / 5%SS) were calculated. The results are shown in Tables 1 and 2.

[0096] [Table 1]

[0097] [Table 2]

[0098] As described above, according to one aspect of the present disclosure, it is possible to obtain a polyol composition that contributes to the production of a flexible polyurethane foam that achieves both reduced hardness during initial compression and suppressed wobbling during high compression. Furthermore, the polyol composition of one aspect of the present disclosure can be mixed with a polyisocyanate composition and injected into a mold set at a predetermined temperature to form a flexible polyurethane foam having the above-mentioned properties.

[0099] Therefore, the flexible polyurethane foam of one embodiment of the present disclosure is useful as a material that requires both reduced hardness at initial compression and suppressed wobbling at high compression, such as a cushioning material for automobile seats, wheelchairs, etc.

Claims

1. A flexible polyurethane foam having a ratio of the stress at 50% compression to the stress at 5% compression, determined from a compression stress-strain curve measured in the second compression operation according to Method E described in JIS K6400-2:2012, of 5.0 or more.

2. 2. The flexible polyurethane foam according to claim 1, wherein the ratio of the stress at 50% compression to the stress at 5% compression is 15 or less.

3. The flexible polyurethane foam according to claim 1, wherein the stress at 50% compression is 300 N / 200 mmφ or more and 800 N / 200 mmφ or less.

4. 2. The flexible polyurethane foam according to claim 1, wherein the ratio of the stress at 25% compression to the stress at 5% compression obtained from the compression stress-strain curve is 3.0 or more.

5. 5. The flexible polyurethane foam according to claim 4, wherein the ratio of the stress at 25% compression to the stress at 5% compression is 6 or less.

6. The flexible polyurethane foam according to claim 4, wherein the stress at 25% compression is 180 N / 200 mmφ or more and 450 N / 200 mmφ or less.

7. The composition contains a polyol compound, a catalyst, a crosslinking agent containing a carbohydrate, a foam stabilizer, and a foaming agent, The following formula (1): Foaming / resinization activity ratio=k2w / k1w (1) [In formula (1), k1w represents the resinification reaction rate constant per unit catalyst concentration, and k2w represents the foaming reaction rate constant per unit catalyst concentration.] The polyol composition for forming flexible polyurethane foams has a foaming / resinification activity ratio represented by the following formula:

Images