Two-component composition for forming flexible polyurethane foam, flexible polyurethane foam, and method for producing the same

Abstract

A two-pack type composition for forming a flexible polyurethane foam, said two-pack type composition comprising a first pack liquid containing at least a polyol component and a second pack liquid containing at least a polyisocyanate component. This two-pack type composition for forming a flexible polyurethane foam additionally contains a catalyst, a foam stabilizer, a foaming agent and a phosphite antioxidant; and if the first pack liquid and the second pack liquid are mixed so as to have an NCO index of 100, the content of the phosphite antioxidant in the mixed liquid is from 50 ppm by mass to 1,100 ppm by mass relative to the total mass of the mixed liquid.

Description

[Technical Field]

[0001] The present invention relates to a two-component composition for forming a flexible polyurethane foam, as well as a flexible polyurethane foam and a method for producing the same. [Background technology]

[0002] Flexible polyurethane foams are used in a wide range of applications, including daily necessities, automotive materials, clothing, sports and leisure goods, medical materials, and civil engineering and construction materials. Among these applications, particularly in seat cushion materials, skin lining materials, sound-absorbing and vibration-damping materials for floors and ceilings, and automotive interior materials such as steering wheels and door trims, in addition to the traditional functions required, there is a demand for reductions in VOCs (volatile organic compounds) and odors emitted from each material in order to improve the interior environment of the vehicle.

[0003] Among VOCs, aldehydes (formaldehyde, acetaldehyde, propionaldehyde, etc.) are particularly thought to be the cause of chemical hypersensitivity.Aldehydes are also odor-causing substances, so measures to address their sources are necessary.

[0004] Various efforts have been made to reduce the amount of aldehydes volatilized from flexible polyurethane foam. For example, Patent Document 1 discloses a method for reducing the amount of aldehydes contained in each raw material constituting polyurethane foam. Specifically, it is said that the amount of aldehydes volatilized from polyurethane foam can be reduced by using a polyether polyol with a low aldehyde content as a raw material for polyurethane foam. Furthermore, Patent Document 2 discloses a method for suppressing the volatilization of aldehydes by applying an aldehyde scavenger to the surface of polyurethane foam (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-132990 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-124743 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method of Patent Document 1 does not sufficiently reduce the amount of aldehydes in the flexible polyurethane foam. Moreover, the method of Patent Document 2 requires application of an aldehyde scavenger after molding the polyurethane foam, which increases the number of work steps.

[0007] The present invention has been made in view of the above circumstances, and its main object is to reduce the amount of aldehydes volatilized from flexible polyurethane foams. [Means for solving the problem]

[0008] Generally, antioxidants are used for the purpose of improving light resistance or scorch resistance in many cases. However, the present inventors have found that the use of a specific amount of a phosphite-based antioxidant significantly reduces the amount of aldehydes that volatilize, and have thus completed the present invention.

[0009] That is, the present invention includes the following embodiments (1) to (16).

[0010] (1) A two-component composition for forming flexible polyurethane foams, comprising a first component containing at least a polyol component and a second component containing at least a polyisocyanate component, further comprising a catalyst, a foam stabilizer, a blowing agent, and a phosphite antioxidant, wherein when the first component and the second component are mixed so as to have an NCO index of 100, the content of the phosphite antioxidant in the mixed liquid is 50 to 1100 ppm by mass relative to the total amount of the mixed liquid.

[0011] (2) The two-component composition for forming flexible polyurethane foams according to (1), wherein the phosphite-based antioxidant has a number-average molecular weight of 500 or more.

[0012] (3) The two-component composition for forming flexible polyurethane foams according to (1) or (2), wherein the phosphite-based antioxidant is contained in the second component.

[0013] (4) The two-component composition for forming flexible polyurethane foams according to any one of (1) to (3), wherein the mixed solution has a phosphorus concentration of 0.0001 to 0.0022 mmol / g.

[0014] (5) The two-component composition for forming flexible polyurethane foams according to any one of (1) to (4), wherein the polyisocyanate component contains diphenylmethane diisocyanate, and the content of the diphenylmethane diisocyanate is 50 to 85 mass% based on the total amount of the polyisocyanate component.

[0015] (6) The two-component composition for forming a flexible polyurethane foam according to (5), wherein the diphenylmethane diisocyanate comprises at least one of 2,2'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate, and the total amount of the 2,2'-diphenylmethane diisocyanate and the 2,4'-diphenylmethane diisocyanate is 10 to 50 mass% based on the total amount of the diphenylmethane diisocyanate.

[0016] (7) The two-component composition for forming flexible polyurethane foams according to any one of (1) to (6), wherein the polyol component comprises polyoxyethylene polyoxypropylene polyol.

[0017] (8) The two-component composition for forming flexible polyurethane foams according to any one of (1) to (7), wherein the phosphite antioxidant comprises a diphosphite having two phosphite structures in the molecule.

[0018] (9) The two-component composition for forming flexible polyurethane foams according to any one of (1) to (8), further comprising a hindered phenol-based antioxidant.

[0019] (10) The two-component composition for forming flexible polyurethane foams according to (9), wherein the mass ratio of the content of the hindered phenol-based antioxidant to the content of the phosphite-based antioxidant in the mixed liquid is 1.1 to 1.4.

[0020] (11) The two-component composition for forming flexible polyurethane foams according to (9), wherein the mass ratio of the content of the hindered phenol-based antioxidant to the content of the phosphite-based antioxidant in the mixed liquid is 0.4 to 0.8.

[0021] (12) A flexible polyurethane foam obtained by subjecting a mixed liquid of the first liquid and the second liquid in the two-component composition for forming a flexible polyurethane foam according to any one of (1) to (11) to reactive foaming.

[0022] (13) A method for producing a flexible polyurethane foam, comprising the step of reacting a polyol component with a polyisocyanate component in the presence of a catalyst, a foam stabilizer, a blowing agent, and a phosphite-based antioxidant to obtain a flexible polyurethane foam, wherein the amount of the phosphite-based antioxidant used is 50 to 1,100 ppm by mass based on the total amount of the flexible polyurethane foam.

[0023] (14) The method for producing a flexible polyurethane foam according to (13), wherein in the step, a first liquid containing at least a polyol component and a second liquid containing at least a polyisocyanate component are mixed together to react the polyol component with the polyisocyanate component.

[0024] (15) The method for producing a flexible polyurethane foam according to (13), wherein in the step, the first liquid and the second liquid in the two-component composition for forming a flexible polyurethane foam according to any one of (1) to (11) are mixed together to react the polyol component with the polyisocyanate component. [Effects of the Invention]

[0025] According to the present invention, the amount of volatilized aldehydes generated from a flexible polyurethane foam can be reduced. For example, by using the two-component composition for forming a flexible polyurethane foam of the present invention, a flexible polyurethane foam with a reduced amount of volatilized aldehydes can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0026] 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.

[0027] An embodiment of the present invention will be described in detail below, although the present invention is not limited to the following embodiment.

[0028] <Two-component composition for forming flexible polyurethane foam> A two-component composition for forming a flexible polyurethane foam (hereinafter also simply referred to as a "two-component composition") in one embodiment comprises a first component containing at least a polyol component (A) and a second component containing at least a polyisocyanate component (B). The first component and the second component are stored separately and are mixed when used (when forming a flexible polyurethane foam).

[0029] The two-component composition further contains a catalyst (C), a foam stabilizer (D), a blowing agent (E), and an antioxidant (F) in addition to the polyol component (A) and the isocyanate component (B). The catalyst (C), the foam stabilizer (D), the blowing agent (E), and the antioxidant (F) may be contained in either the first component or the second component. For example, the first component may contain the polyol component (A), the catalyst (C), the foam stabilizer (D), and the blowing agent (E), the second component may contain the isocyanate component (B), and at least one of the first component and the second component may contain the antioxidant (F).

[0030] The antioxidant (F) includes a phosphite-based antioxidant (F-1). The content of the phosphite-based antioxidant (F-1) is 50 to 1100 ppm by mass based on the total amount of the two-component composition for forming flexible polyurethane foams.

[0031] Here, the total amount of the two-component composition for forming flexible polyurethane foams refers to the total amount of the mixed liquid obtained when the first and second liquids are mixed so that the NCO index is 100. In other words, the content of the phosphite-based antioxidant (F-1) is "an amount such that when the first and second liquids are mixed so that the NCO index is 100, the content of the phosphite-based antioxidant (F-1) in the mixed liquid is 50 to 1100 ppm by mass relative to the total amount of the mixed liquid." Note that the mixed liquid refers to the mixed liquid immediately after mixing the first and second liquids, in which reaction and foaming have not yet progressed. Therefore, the content of the phosphite-based antioxidant (F-1) in the mixed liquid is equal to the sum of the content of the phosphite-based antioxidant in the first liquid and the content of the phosphite-based antioxidant in the second liquid to be mixed. Furthermore, the total amount of the mixed liquid is equal to the sum of the total amounts of the first liquid and the second liquid to be mixed.

[0032] The NCO index refers to the percentage of the number of moles of all isocyanate groups (NCO groups) in the isocyanate group-containing compound relative to the number of moles of all active hydrogen groups in the active hydrogen group-containing compound contained in the mixed solution (NCO groups / active hydrogen groups × 100). Note that the active hydrogen group-containing compound also includes water.

[0033] The two-component composition of the present embodiment having the above-described characteristics can reduce the amount of aldehydes volatilized from flexible polyurethane foam.

[0034] Each component contained in the two-component composition will be described below.

[0035] [Polyol component (A)] The polyol component (A) is a compound having multiple hydroxyl groups, and forms a polyurethane by polyaddition with the polyisocyanate component (B). The polyol component (A) preferably contains at least one selected from the group consisting of polyether polyols and polyester polyols, from the viewpoint of being able to adjust the nominal functionality, number average molecular weight, etc., and to obtain a wide range of hardness and elastic modulus. The polyol component (A) may be used singly or in combination of multiple types.

[0036] Examples of polyether polyols include polypropylene ether polyol, polyoxyethylene polyoxypropylene polyol, and polytetramethylene ether glycol (PTG).

[0037] 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.

[0038] From the viewpoint of promoting cell breakage of flexible polyurethane foams and tending to more significantly achieve the effects of the present invention, the polyol component (A) preferably contains a polyether polyol having a polyoxyalkylene chain containing oxyethylene units and oxypropylene units as constituent units (for example, a polyoxyalkylene chain consisting of a copolymer of oxyethylene and oxypropylene), and more preferably contains a polyoxyethylene polyoxypropylene polyol. The nominal functionality of such a polyol is 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).

[0039] From the viewpoints of facilitating obtaining a hardness distribution of a flexible polyurethane foam and further improving durability, the polyol component (A) preferably contains a polyether polyol containing oxyethylene units as main structural units. The content of oxyethylene units in the polyether polyol containing oxyethylene units as main structural units is more than 50% by mass, preferably 60 to 90% by mass, and more preferably 60 to 80% by mass.

[0040] The content of the polyether polyol containing oxyethylene units as main structural units may be 0.5% by mass or more, based on the total amount of polyol component (A), 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% by mass or less, based on the total amount of polyol component (A), 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 0.5 to 5% by mass, based on the total amount of polyol component (A).

[0041] The number average molecular weight of the polyol component (A) may be 1,000 or more, from the viewpoint of easily obtaining a flexible polyurethane foam having sufficient flexibility. The number average molecular weight of the polyol component (A) may be 10,000 or less, from the viewpoint of easily obtaining a flexible polyurethane foam having sufficient hardness. From these viewpoints, the number average molecular weight of the polyol component (A) is preferably 1,000 to 10,000. When the polyol component (A) contains multiple types of polyol compounds, it is preferable that the hydroxyl value of at least one polyol compound is within the above range, and it is preferable that the hydroxyl values ​​of all of the polyol compounds are within the above range.

[0042] The nominal functionality of the polyol component (A) may be 2 or more from the viewpoint of obtaining a good wet heat compression set, which is an index of durability. The nominal functionality of the polyol component (A) may be 4 or less from the viewpoint of easily obtaining a flexible polyurethane foam with sufficient flexibility. From these viewpoints, the nominal functionality is preferably 2 to 4. When the polyol component (A) contains multiple types of polyol compounds, it is preferable that the nominal functionality of at least one polyol compound is in the above-mentioned range, and it is preferable that the nominal functionality of all polyol compounds is in the above-mentioned 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.

[0043] From the above viewpoints, the polyol component (A) preferably contains a polyether polyol or polyester polyol having a number average molecular weight of 1,000 to 10,000 and a nominal functionality of 2 or more.

[0044] The hydroxyl value of the polyol component (A) may be 20 to 200 mgKOH / g. When the hydroxyl value of the polyol component (A) is 20 mgKOH / g or more, a flexible polyurethane foam with sufficient hardness is likely to be obtained. When the hydroxyl value of the polyol component (A) is 200 mgKOH / g or less, a flexible polyurethane foam with sufficient flexibility is likely to be obtained. When the polyol component (A) contains multiple polyol compounds, it is preferable that the hydroxyl value of at least one polyol compound is within the above range, and it is preferable that the hydroxyl values ​​of all polyol compounds are within the above range. The hydroxyl value means the number of milligrams (mg) of potassium hydroxide equivalent to the hydroxyl groups in 1 g of a sample, and is measured in accordance with JIS K1557.

[0045] As the polyol component (A), a polymer polyol obtained by polymerizing a vinyl monomer in a polyol may be used for the purpose of adjusting hardness. The vinyl monomer may be polymerized by a conventional method (e.g., radical polymerization). Examples of such polymer polyols include those obtained by polymerizing a vinyl monomer in a polyalkylene polyol, such as the polyethylene polypropylene polyol, in the presence of a radical initiator, followed by stable dispersion. Examples of vinyl monomers include acrylonitrile, styrene, vinylidene chloride, hydroxyalkyl methacrylate, and alkyl methacrylate. Among these, acrylonitrile and styrene are preferred. Examples of such polymer polyols include EL-910 and EL-923 (trade names) manufactured by AGC Corporation, and FA-728R (trade name) manufactured by Sanyo Chemical Industries, Ltd.

[0046] [Polyisocyanate component (B)] The polyisocyanate component (B) is a compound having multiple isocyanate groups. At least one selected from the group consisting of diphenylmethane diisocyanate (MDI) and polyphenylene polymethylene polyisocyanate (P-MDI) is preferably used as the polyisocyanate component (B). In addition to a mixture of MDI and P-MDI, various modifications of MDI or P-MDI, such as urethane-modified, urea-modified, allophanate-modified, nurate-modified, and biuret-modified, may also be used as the polyol component (B). One type of polyisocyanate component (B) may be used alone, or multiple types may be used in combination. MDI exists in three isomers: 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), and 2,2'-diphenylmethane diisocyanate (2,2'-MDI). As MDI, one of these may be used alone, or two or more may be used in combination.

[0047] The MDI content in the polyisocyanate component (B) is preferably 50 to 85% by mass. Here, the MDI content can be expressed as the content of diphenylmethane diisocyanate relative to the total amount of polyisocyanate components. When the MDI content is 85% by mass or less, the low-temperature storage stability of the second liquid containing the polyisocyanate component (B) and the durability of the resulting flexible polyurethane foam tend to be improved. Furthermore, when the MDI content is 50% by mass or more, the elongation of the flexible polyurethane foam is less likely to decrease due to an increase in crosslink density, making it easier to obtain sufficient foam strength. From these viewpoints, the MDI content may be 60% by mass or more, or 70% by mass or more, or may be 80% by mass or less.

[0048] The total amount of 2,2'-diphenylmethane diisocyanate (2,2'-MDI) and 2,4'-diphenylmethane diisocyanate (2,4'-MDI) is preferably 10 to 50% by mass relative to the total amount of diphenylmethane diisocyanate (MDI). In other words, the isomer content in MDI (the sum of the 2,2'-MDI content and the 2,4'-MDI content based on the total amount of MDI) is preferably 10 to 50% by mass. When the isomer content is 10% by mass or more, the storage stability of the second liquid containing the polyisocyanate component (B) at low temperatures tends to be improved, and the molding stability of the flexible polyurethane foam tends to be improved, and the occurrence of foam collapse during foaming tends to be suppressed. Furthermore, when the isomer content is 50% by mass or less, the reactivity is improved, and problems such as an extension of the molding cycle and a high closed cell ratio of the foam, which results in less shrinkage after molding, are unlikely to occur.

[0049] [Catalyst (C)] The catalyst may be any of various urethanization catalysts known in the art. Examples of the catalyst (C) include triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N,N',N',N''-pentamethyldiethylenetriamine, bis-(2-dimethylaminoethyl)ether, triethylenediamine, 1,8-diaza-bicyclo[5.4.0]undecene-7, 1,2-dimethylimidazole, dimethylethanolamine, N,N-dimethyl-N-hexanolamine, and organic acid salts thereof; organometallic compounds such as stannous octoate and zinc naphthenate; and amines having active hydrogen, such as 2-hydroxymethyltriethylenediamine, N,N,N'-trimethyl-N'-hydroxyethyl-bisaminoethyl ether, N,N-dimethylethanolamine, and N,N-diethylethanolamine. The catalyst (C) may be used alone or in combination of two or more kinds.

[0050] As catalyst (C), amines containing active hydrogen are preferably used because they react with isocyanates and are incorporated into the urethane resin without generating amine emissions. Catalysts containing primary amino groups (-NH2) and secondary amino groups (-NHR) also contain active hydrogen and react with isocyanates, but amines are more reactive than alcohols and tend to form urea bonds early in the reaction. This can result in insufficient catalytic function, leading to reduced physical properties such as tensile strength and elongation in the flexible polyurethane foam. From this perspective, it is preferable that catalyst (C) does not contain primary or secondary amino groups.

[0051] When the catalyst (C) is an amine having active hydrogen, the catalyst (C) is preferably contained in the first liquid from the viewpoint of preventing the catalyst (C) from reacting with isocyanate.

[0052] The content of catalyst (C) is preferably such that the content of catalyst (C) in the mixed liquid obtained when the first liquid and the second liquid are mixed so that the NCO index is 100 is 0.01 to 10 mass% relative to the total amount of polyol component (A) in the mixed liquid. When the content is 0.1 mass% or more, sufficient curing is likely to occur. When the content is 10 mass% or less, moldability tends to be improved. From the above viewpoints, when catalyst (C) is contained in the first liquid, the content of catalyst (C) relative to the total amount of polyol component (A) in the first liquid is preferably 0.01 to 10 mass%.

[0053] [Foam stabilizer (D)] The foam stabilizer (D) is, for example, a surfactant. A wide variety of surfactants commonly used in this technical field can be used as the foam stabilizer (D). Among surfactants, organosilicon-based (e.g., silicone-based) surfactants are preferably used. Specific examples of the foam stabilizer (D) include SZ-1327, SZ-1325, SZ-1336, and SZ-3601 manufactured by Dow-Toray Industries, Y-10366 and L-3639 manufactured by Momentive, and B-8724LF2 and B-8715LF2 manufactured by Evonik. The foam stabilizer (D) may be used singly or in combination.

[0054] The foam stabilizer (D) may contain active hydrogen, and therefore is preferably contained in the first liquid from the viewpoint of preventing the foam stabilizer (D) from reacting with isocyanate.

[0055] The content of the foam stabilizer (D) is preferably such that the content of the foam stabilizer (D) in the mixed liquid obtained when the first liquid and the second liquid are mixed so that the NCO index is 100 is 0.1 to 3.0 mass% relative to the total amount of the polyol component (A) in the mixed liquid. When the content is 0.1 mass% or more, the cells are easily homogenized. When the content is 3.0 mass% or less, a urethane foam with good physical properties is easily obtained. From the above viewpoints, when the foam stabilizer (D) is contained in the first liquid, the content of the foam stabilizer (D) relative to the total amount of the polyol component (A) in the first liquid is preferably 0.1 to 3.0 mass%.

[0056] [Foaming agent (E)] The blowing agent (E) is, for example, water. Water reacts with the isocyanate group to form a high-hardness urea group and generate carbon dioxide gas, which can foam the mixture of the first and second liquids.

[0057] The content of water relative to the total amount of the blowing agent (E) is, for example, more than 50 mass%, may be 70 mass% or more, or 90 mass% or more, or may be 100 mass% or less. The content of water relative to the total amount of the blowing agent (E) may be, for example, more than 50 mass%, may be 70 mass% or more, or 90 mass% or more, or may be 100 mass% or less.

[0058] As the blowing agent (E), any blowing agent may be used in addition to water. For example, a small amount of a low-boiling organic compound such as cyclopentane or isopentane may be used in combination with water. Alternatively, for example, air, nitrogen gas, liquefied carbon dioxide, or the like may be mixed and dissolved in a mixture of the first and second liquids using a gas loading device to foam the mixture.

[0059] When water having active hydrogen is used as the blowing agent (E), a foam stabilizer (E) is preferably contained in the first liquid from the viewpoint of preventing the blowing agent (E) from reacting with isocyanate.

[0060] The content of the blowing agent (E) is preferably such that the content of the blowing agent (E) in the mixed liquid obtained when the first liquid and the second liquid are mixed so that the NCO index is 100 is 0.5 to 10 mass%, more preferably 0.5 to 8.0 mass%, relative to the total amount of the polyol component (A) in the mixed liquid. When the content is 0.5 mass% or more, a sufficient amount of foaming is likely to be obtained. When the content is 10 mass% or less, foaming is likely to be stable. From the above viewpoints, when the blowing agent (E) is contained in the first liquid, the content of the blowing agent (E) relative to the total amount of the polyol component (A) in the first liquid is preferably 0.5 to 10 mass%, more preferably 0.5 to 8.0 mass%.

[0061] [Antioxidant (F)] The antioxidant (F) includes a phosphite-based antioxidant (F-1). The phosphite-based antioxidant (F-1) may be an inorganic compound or an organic compound. The phosphite-based antioxidant (F-1) may be used alone or in combination of two or more types.

[0062] Examples of the phosphite antioxidant, which is an inorganic compound, include inorganic phosphates such as monosodium phosphate, disodium phosphate, trisodium phosphate, sodium phosphite, calcium phosphite, magnesium phosphite, manganese phosphite, sodium hypophosphite, calcium hypophosphite, and potassium hypophosphite.

[0063] Examples of the phosphite antioxidants that are organic compounds include triphenyl phosphite, trioctadecyl phosphite, tridecyl phosphite, triisodecyl phosphite, trinonylphenyl phosphite, diphenylisodecyl phosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl)phosphite, Examples of organic phosphorus compounds include distearyl pentaerythritol diphosphite, tetra-(C12-15 alkyl)-4,4'-isopropylidenediphenyl diphosphite (for example, tetra(tridecyl-4,4'-isopropylidenediphenyl diphosphite), 2,2-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, distearyl pentaerythritol diphosphite, and cyclic neopentanetetraylbis(2,6-di-t-butyl-4-methylphenyl phosphite).

[0064] From the viewpoint of more effectively suppressing the volatilization amount of aldehydes generated from flexible polyurethane foam, the phosphite-based antioxidant (F-1) is preferably an organic phosphorus compound, more preferably a monophosphite or diphosphite having one or two phosphite structures in the molecule, and even more preferably a diphosphite. Preferred monophosphites include triisodecyl phosphite, trinonylphenyl phosphite, and trioctadecyl phosphite. Preferred diphosphites include tetra-(C12-15 alkyl)-4,4'-isopropylidene diphenyl diphosphite, distearyl pentaerythritol diphosphite, and cyclic neopentanetetraylbis(2,6-di-t-butyl-4-methylphenyl phosphite).

[0065] The number-average molecular weight of the phosphite-based antioxidant (F-1) is preferably 500 or more. By using a phosphite-based antioxidant with a number-average molecular weight of 500 or more, the amount of volatilization of aldehydes generated from a flexible polyurethane foam can be more effectively suppressed. From the viewpoint of achieving such an effect more significantly, the number-average molecular weight of the phosphite-based antioxidant may be 750 or more or 1000 or more. From the viewpoint of ensuring a sufficient phosphorus concentration and easily achieving the effect of reducing the amount of volatilization of aldehydes, the number-average molecular weight of the phosphite-based antioxidant (F-1) may be 3000 or less, 2000 or less, or 1500 or less. When a phosphite-based antioxidant with a number-average molecular weight of 500 or more is used as the phosphite-based antioxidant (F-1), a phosphite-based antioxidant with a number-average molecular weight of less than 500 may be used in combination. However, from the viewpoint of preventing the antioxidant itself from volatilizing, it is preferable not to use a phosphite-based antioxidant with a number-average molecular weight of less than 500.

[0066] As the phosphite-based antioxidant (F-1), specifically, for example, Adeka STAB 1500 and Adeka STAB 3010 (both trade names) manufactured by Adeka Corporation can be suitably used.

[0067] The phosphite-based antioxidant (F-1) is preferably contained in the second liquid from the viewpoint that it is less susceptible to hydrolysis and can stably reduce the amount of aldehyde volatilized from the flexible polyurethane foam.

[0068] The content of the phosphite-based antioxidant (F-1) is an amount such that the content of the phosphite-based antioxidant (F-1) in the mixed liquid obtained when the first liquid and the second liquid are mixed so that the NCO index is 100 is 50 to 1100 ppm by mass relative to the total amount of the mixed liquid. From the viewpoint of obtaining a more significant effect of reducing the amount of volatilization of aldehydes, the content may be 100 ppm by mass or more, 200 ppm by mass or more, 300 ppm by mass or more, 400 ppm by mass or more, 500 ppm by mass or more, or 600 ppm by mass or more, or may be 800 ppm by mass or less. From these viewpoints, the content is preferably 100 to 800 ppm by mass.

[0069] When the phosphite-based antioxidant (F-1) is contained in the first liquid, the content of the phosphite-based antioxidant (F-1) relative to the total amount of the polyol component (A) in the first liquid is preferably 0.02 to 0.10 mass%, more preferably 0.03 to 0.08 mass%.

[0070] When the phosphite-based antioxidant (F-1) is contained in the second liquid, the content of the phosphite-based antioxidant (F-1) relative to the total amount of the polyisocyanate component (B) in the second liquid is preferably 0.01 to 0.30 mass%, more preferably 0.02 to 0.28 mass%.

[0071] The antioxidant (F) may further contain an antioxidant other than the phosphite-based antioxidant (F-1). Examples of such antioxidants include hindered phenol-based antioxidants (F-2), thioether-based antioxidants (F-3), and hindered amine-based antioxidants (F-4). Among these, the hindered phenol-based antioxidant (F-2) is preferred.

[0072] Examples of the hindered phenol antioxidant (F-2) include octyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3 Examples of the hydroxybenzoates include octyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and pentaerythritol tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate).

[0073] The hindered phenol-based antioxidant (F-2) is preferably contained in the first liquid from the viewpoint of suppressing oxidative deterioration of the polyol component.

[0074] The content of the hindered phenol-based antioxidant (F-2) is preferably an amount such that the content of the hindered phenol-based antioxidant (F-2) in the mixed liquid obtained when the first liquid and the second liquid are mixed so as to have an NCO index of 100 is 50 to 1000 ppm by mass relative to the total amount of the mixed liquid. When the content is 50 to 1000 ppm by mass, the amount of aldehydes volatilized from the flexible polyurethane foam can be more effectively suppressed.

[0075] From the viewpoint of more effectively suppressing the volatilization amount of propionaldehyde among aldehydes, the content of the hindered phenol-based antioxidant (F-2) is preferably an amount such that the mass ratio of the content of the hindered phenol-based antioxidant (F-2) in the mixed liquid to the content of the phosphite-based antioxidant (F-1) in the mixed liquid obtained when the first liquid and the second liquid are mixed so that the NCO index becomes 100 (content of hindered phenol-based antioxidant / content of phosphite-based antioxidant) is 1.1 to 1.4.

[0076] From the viewpoint of more effectively suppressing the amount of volatilization of formaldehyde among aldehydes, the content of the hindered phenol-based antioxidant (F-2) is preferably an amount such that the mass ratio of the content of the hindered phenol-based antioxidant (F-2) in the mixed liquid to the content of the phosphite-based antioxidant (F-1) in the mixed liquid obtained when the first liquid and the second liquid are mixed so that the NCO index becomes 100 (content of hindered phenol-based antioxidant / content of phosphite-based antioxidant) is 0.4 to 0.8.

[0077] The content (total amount) of the antioxidant (F) is preferably an amount such that the content of the antioxidant (F) in the mixed liquid obtained when the first liquid and the second liquid are mixed so as to have an NCO index of 100 is 100 to 2500 ppm by mass relative to the total amount of the mixed liquid. When the content is 100 to 2500 ppm by mass, the amount of aldehydes volatilized from the flexible polyurethane foam can be more effectively suppressed.

[0078] The components contained in the two-component composition have been described above, but the two-component composition may further contain other components in addition to the above components. Examples of other components include fillers such as calcium carbonate and barium sulfate, and various known additives and auxiliaries such as flame retardants, plasticizers, colorants, and anti-fungal agents. These can be used as needed.

[0079] From the viewpoint of facilitating the production of flexible polyurethane foams having good physical properties such as tensile strength and elongation, the two-component composition preferably does not contain a compound having at least one of a primary amino group (-NH2) and a secondary amino group (-NHR). More specifically, it is preferable that the two-component composition does not contain an amine represented by the following formula (1) or (2): [ka] [ka]

[0080] In the above formula, Ra and Rb are random arrangements of constitutional units represented by the following formula (3), (4) and / or (5), respectively. [ka] [ka] [ka]

[0081] In the above formula, R 4 , R 5 , R 6 and R 7 are each independently -H or -CH3, R a contains 3 to 17 nitrogen atoms and R b contains 2 to 16 nitrogen atoms.

[0082] From the viewpoint of obtaining a more significant effect of reducing the amount of volatile aldehydes, the content of phosphorus in the two-component composition is preferably an amount such that the phosphorus concentration in the mixed solution obtained when the first and second components are mixed so as to have an NCO index of 100 is 0.0001 to 0.0022 mmol / g. From the viewpoint of obtaining the above effect more easily, the phosphorus concentration may be 0.0005 mmol / g or more, 0.0010 mmol / g or more, or 0.0013 mmol / g or more, or may be 0.0018 mmol / g or less. The phosphorus concentration is an elemental equivalent value measured by ICP elemental analysis.

[0083] The two-component composition described above forms a flexible polyurethane foam by reactively foaming a mixture of the first and second components. The two-component composition is usually used by mixing the first and second components so that the NCO index is 100, but the mixing ratio of the first and second components can be changed as long as the content of the phosphite antioxidant (F-1) in the mixture is 50 to 1100 mass ppm relative to the total amount of the mixture.

[0084] <Method for manufacturing flexible polyurethane foam> A method for producing a flexible polyurethane foam according to one embodiment includes a step of reacting a polyol component (A) with a polyisocyanate component (B) in the presence of a catalyst (C), a foam stabilizer (D), a blowing agent (E), and an antioxidant (F) to obtain a flexible polyurethane foam.

[0085] In the production method of this embodiment, a phosphite-based antioxidant (F-1) is used as the antioxidant (F). The amount of the phosphite-based antioxidant (F-1) used is 50 to 1100 ppm by mass based on the total amount of the flexible polyurethane foam. Here, the total amount of the flexible polyurethane foam is equal to the total amount of the components used in the production of the flexible polyurethane foam (e.g., polyol component (A), polyisocyanate component (B), catalyst (C), foam stabilizer (D), blowing agent (E), antioxidant (F), and other optional components). Therefore, the total amount of the flexible polyurethane foam can be rephrased as the total amount of the polyol component (A), polyisocyanate component (B), catalyst (C), foam stabilizer (D), blowing agent (E), antioxidant (F), and other optional components.

[0086] In the above process, for example, the polyol component (A), polyisocyanate component (B), catalyst (C), foam stabilizer (D), blowing agent (E), antioxidant (F), and other optional components are mixed, and the mixed liquid is subjected to reactive foaming. The mixed liquid can be obtained, for example, by previously preparing a first liquid containing at least the polyol component (A) and a second liquid containing at least the polyisocyanate component (B) and then mixing them. In this case, the catalyst (C), foam stabilizer (D), blowing agent (E), and antioxidant (F) are contained in the first liquid and / or second liquid. The first liquid and second liquid may be the first liquid and second liquid in the two-component composition of the above embodiment.

[0087] The NCO index during mixing is preferably 70 or more from the viewpoints of improving foam durability and suppressing an excessive increase in closed cell property. The NCO index during mixing is preferably 140 or less, more preferably 120 or less, from the viewpoints of preventing unreacted isocyanate from remaining for a long time, thereby preventing an extension of the molding cycle, and preventing a delay in polymerization, thereby improving the moldability of the polyurethane foam. From these viewpoints, the NCO index during mixing is preferably 70 to 140, more preferably 70 to 120.

[0088] The method for producing a flexible polyurethane foam may be a method for producing a flexible polyurethane molded foam (hereinafter referred to as a flexible molded foam) by injecting the mixed liquid (unfoamed raw liquid) into a mold and then foaming and curing it.The method for producing a flexible polyurethane foam may also be a method for producing a flexible polyurethane slab foam (hereinafter referred to as a flexible slab foam) by supplying the mixed liquid to a foaming container or continuously supplying the mixed liquid onto a belt conveyor and foaming it.

[0089] In the method for producing flexible molded foam, the mold temperature when the mixed liquid (unfoamed raw liquid) is poured into the mold is usually 30 to 80°C, and preferably 45 to 70°C. If the mold temperature when the mixed liquid (unfoamed raw liquid) is poured into the mold is 30°C or higher, extension of the production cycle due to a decrease in reaction rate is unlikely. Furthermore, if the mold temperature is 80°C or lower, the reaction between water and isocyanate tends to proceed more slowly than the reaction between polyol and isocyanate, and the moldability of the polyurethane foam tends to be good.

[0090] The curing time for foaming and curing the mixed liquid (unfoamed raw liquid) is preferably 10 minutes or less, more preferably 7 minutes or less, taking into consideration the production cycle of a typical flexible molded foam.

[0091] When producing a flexible molded foam, the above components can be mixed using a high-pressure foaming machine, a low-pressure foaming machine or the like, as in the case of ordinary flexible molded foams.

[0092] The polyol component (A) and the isocyanate component (B) are preferably mixed immediately before foaming. As described above, components other than the polyol component (A) and the isocyanate component (B) may be premixed with the polyol component (A) or the isocyanate component (B) to the extent that the storage stability of the raw materials and the change in reactivity over time are not affected. The obtained first and second liquids may be used immediately after preparation, or may be stored and then used as needed. In the case of a foaming device capable of simultaneously introducing more than two components into the mixing section, the polyol component (A), the isocyanate component (B), the catalyst (C), the foam stabilizer (D), the blowing agent (E), the antioxidant (F), etc. may also be introduced individually into the mixing section.

[0093] Examples of mixing methods include dynamic mixing, in which mixing is performed in the machine head mixing chamber of the foaming machine, and static mixing, in which mixing is performed in the liquid delivery pipe. These mixing methods may be used in combination. Mixing of gaseous components such as physical foaming agents with liquid components is often performed by static mixing. Furthermore, mixing of components that can be stably stored as liquids is often performed by dynamic mixing. The foaming device is preferably a high-pressure foaming device that does not require solvent cleaning of the mixing section.

[0094] After the mixing, the resulting mixture is discharged into a mold, foamed and cured, and then demolded. To facilitate the demolding, it is also preferable to apply a release agent to the mold in advance. The release agent used may be a release agent commonly used in the molding processing field.

[0095] The product (flexible molded foam) after demolding can be used as is, but it is preferable to destroy the cell membranes of the foam by compression or decompression to stabilize the appearance and dimensions of the product. Compression and decompression may be carried out by known methods.

[0096] A method for producing flexible slab foam may involve using a multi-component foaming machine equipped with a rotor-rotating or high-pressure impingement mixing head. All components are mixed in the head, and the mixed liquid is then continuously supplied onto a belt conveyor for foaming. In this method, an oven adjusted to 30 to 80°C is preferably installed along the belt conveyor path to ensure uniform curing and a sufficient expansion ratio. A mixing head known in the art for mixing raw materials may be used. Alternatively, a method known as a batch block method may be used for producing flexible slab foam, in which all components are mixed in a batch mixing tank and then poured into a foaming container for foaming. Flexible polyurethane foam can be obtained by the above-mentioned production method. [Example]

[0097] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0098] In the following examples and comparative examples, the following raw materials were used. [Polyol component] Polyol 1: Polyoxyethylene polyoxypropylene polyol (NEF-693 (trade name) manufactured by Tosoh Corporation, nominal functionality (average functionality) = 3.0, hydroxyl value = 24 mg KOH / g, oxyethylene units = 14.6 mass%, number average molecular weight = 7000) Polyol 2: Polyoxyethylene polyoxypropylene polyol (NEF-740 (trade name) manufactured by Tosoh Corporation, nominal functionality (average functionality) = 3.0, hydroxyl value = 24 mg KOH / g, oxyethylene units = 70 mass%, number average molecular weight = 7000) [Polyisocyanate component] Isocyanate 1: Polyisocyanate containing polyphenylene polymethylene polyisocyanate, with an MDI content of 80% by mass and an isomer content of 38% by mass (CEF-551 (trade name) manufactured by Tosoh Corporation) [catalyst] Catalyst 1: 2-hydroxymethyltriethylenediamine (R-ZETA HD (trade name) manufactured by Tosoh Corporation) Catalyst 2: N,N,N'-trimethyl-N'-hydroxyethyl-bisaminoethyl ether (TOYOCAT RX-10 (trade name) manufactured by Tosoh Corporation) [Foam stabilizer] Foam stabilizer 1: Silicone foam stabilizer (L-3639 (trade name) manufactured by Momentive) [Foaming agent] ·Water (city water) [Antioxidants] Antioxidant 1: Phosphite-based antioxidant (ADEKA STAB 1500 (trade name) manufactured by ADEKA Corporation, number average molecular weight = 1112) Antioxidant 2: Phosphite-based antioxidant (ADEKA STAB 3010 (trade name) manufactured by ADEKA Corporation, number average molecular weight = 503) Antioxidant 3: Thioether-based antioxidant (ADEKA STAB AO-26 (trade name) manufactured by ADEKA Corporation) Antioxidant 4: Hindered phenol antioxidant (Irganox 1135 (trade name) manufactured by BASF Japan Ltd.)

[0099] <Examples 1 to 8 and Comparative Examples 1 to 5> (Preparation of Polyol Composition (First Liquid)) After a reactor equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer was purged with nitrogen, 100 g of polyol 1, 1.0 g of polyol 2, 0.8 g of catalyst 1, 0.2 g of catalyst 2, 1.0 g of foam stabilizer 1, and 3.6 g of water were charged and stirred at 23°C for 0.5 hours to obtain polyol composition (P-1). Other polyol compositions (P-2 to P-3) were also prepared in the same manner as polyol composition (P-1) by charging the respective raw materials as shown in Table 1.

[0100] (Preparation of Isocyanate Composition (Second Liquid)) After replacing the atmosphere in a reactor equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer with nitrogen, 100 g of Isocyanate 1 and 0.08 g of Antioxidant 1 were added and stirred at 23°C for 0.5 hours to obtain Isocyanate Composition (I-1). The other Isocyanate Compositions (I-2 to I-10) were also prepared in the same manner as Isocyanate Composition (I-1) by adding the respective raw materials as shown in Table 1.

[0101] (Preparation of flexible polyurethane foam) Flexible polyurethane foams were produced using the polyol composition and isocyanate composition in the combinations shown in Table 1. Specifically, first, the liquid temperatures of the isocyanate composition and the polyol composition (a mixture of all raw materials other than the isocyanate composition) were adjusted to 24°C to 26°C, respectively. Next, a predetermined amount of the isocyanate composition was added to the polyol composition so that the NCO index (the percentage of NCO groups relative to the number of active hydrogen atoms present in the blend) was 100, and the mixture was mixed for 7 seconds using a mixer (7,000 rpm). The resulting mixture was then poured into a mold, and the mixture was reactively foamed. The reactive foaming conditions were as follows: [conditions] Mold temperature: 60~65℃ ·Mold shape: 300mm x 300mm x 100mm Mold material: Aluminum Cure time: 4 minutes

[0102] After molding a flexible polyurethane foam by the above method, the resulting molded product of the flexible polyurethane foam (molded product) was removed from the mold.

[0103] [Table 1]

[0104] (Moldability evaluation) The moldability of the flexible polyurethane foam was evaluated during molding. Specifically, if the polyurethane foam could be molded without collapsing after reaching its maximum height, or shrinking immediately after foaming or after curing, a rating of A was given. The results are shown in Table 2.

[0105] (Measurement of volatile amount of aldehydes) The amounts of formaldehyde, acetaldehyde, and propionaldehyde volatilized from the resulting molded flexible polyurethane foams (molded articles) were measured. Specifically, rectangular parallelepiped test pieces, each measuring 100 mm long x 70 mm wide and including a skin surface, and 80 mm thick, were cut from each molded article. The test pieces were then sealed in a 10-L sampling bag together with 4 L of nitrogen. The sampling bag was then heated at 65°C for 2 hours, and the volatile components were collected in a dedicated collection tube (DNPH cartridge). The collected volatile components were analyzed by high-performance liquid chromatography to measure the volatilization (emission) amounts of each aldehyde gas (formaldehyde, acetaldehyde, and propionaldehyde). The results are shown in Table 2. The high-performance liquid chromatography measurement conditions were as follows: [conditions] Equipment: Shimadzu LC-20A series Column: TSKgel ODS-80TsQA Mobile phase: acetonitrile / water ·Mobile phase speed: 1.0mL / min Column temperature: 40℃ ·Detector: UV (λ=360nm) Calibration curve: Prepare a standard sample solution using aldehyde-DNPH in acetonitrile.

[0106] The measured volatilization amount (emission amount) of each aldehyde gas (formaldehyde, acetaldehyde, and propionaldehyde) was evaluated according to the following criteria. [Formaldehyde volatility] Excellent: 0.25 μg / sample or less Very good: above 0.25 μg / sample, below 0.30 μg / sample Good: Over 0.30 μg / sample, 0.35 μg / sample or less Poor: Over 0.35 μg / sample [Amount of acetaldehyde volatilized] Excellent: 0.20 μg / sample or less Very good: above 0.20 μg / sample, below 0.25 μg / sample Good: Over 0.25μg / sample, 0.30μg / sample or less Poor: Over 0.30 μg / sample [Propionaldehyde volatility] Excellent: 0.08 μg / sample or less Very good: above 0.08 μg / sample, below 0.13 μg / sample Good: Over 0.13 μg / sample, 0.18 μg / sample or less Defective: over 0.18 μg / sample

[0107] [Table 2]

[0108] As shown in the evaluation results of Comparative Examples 1 and 5 in Table 2, when the phosphite-based antioxidant (F-1) was not used, the amount of volatilization of each aldehyde was confirmed to be large. Furthermore, as shown in the evaluation result of Comparative Example 2, when a flexible polyurethane foam was molded using a thioether-based antioxidant instead of the phosphite-based antioxidant (F-1), the amount of volatilization of aldehydes was also confirmed to be large. Furthermore, as shown in the evaluation results of Comparative Examples 3 and 4, it was confirmed that the amount of volatilization of aldehydes also increased when the amount of phosphite-based antioxidant (F-1) used was excessive. Comparing the above examples and comparative examples clearly shows that the present invention can provide a flexible polyurethane foam capable of reducing the amount of volatilization of aldehydes, and the significance and outstanding excellence of the configuration of the present invention can be understood.

Claims

1. A two-component composition for forming a flexible polyurethane foam, comprising a first component containing at least a polyol component and a second component containing at least a polyisocyanate component, further comprising a catalyst, a foam stabilizer, a blowing agent, and a phosphite-based antioxidant; the phosphite antioxidant comprises tetra-(C12-15 alkyl)-4,4'-isopropylidenediphenyl diphosphite; A two-component composition for forming flexible polyurethane foams, wherein, when the first component and the second component are mixed so as to give an NCO index of 100, the content of the phosphite-based antioxidant in the mixed solution is 50 to 1,100 ppm by mass relative to the total amount of the mixed solution.

2. A two-component composition for forming flexible polyurethane foam as described in claim 1, wherein when the first liquid and the second liquid are mixed so that the NCO index is 100, the content of the phosphite-based antioxidant in the mixed liquid is 600 to 800 ppm by mass relative to the total amount of the mixed liquid.

3. 3. The two-component composition for forming flexible polyurethane foam according to claim 1, wherein the phosphite-based antioxidant is contained in the second component.

4. The two-component composition for forming a flexible polyurethane foam according to any one of claims 1 to 3, wherein the mixed solution has a phosphorus concentration of 0.0001 to 0.0022 mmol / g.

5. the polyisocyanate component comprises diphenylmethane diisocyanate; The two-component composition for forming a flexible polyurethane foam according to any one of claims 1 to 4, wherein the content of the diphenylmethane diisocyanate is 50 to 85 mass% based on the total amount of the polyisocyanate components.

6. the diphenylmethane diisocyanate includes at least one of 2,2'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate; 6. The two-component composition for forming flexible polyurethane foam according to claim 5, wherein the total amount of the 2,2'-diphenylmethane diisocyanate and the 2,4'-diphenylmethane diisocyanate is 10 to 50% by mass based on the total amount of the diphenylmethane diisocyanate.

7. The two-component composition for forming flexible polyurethane foam according to any one of claims 1 to 6, wherein the polyol component comprises a polyoxyethylene polyoxypropylene polyol.

8. The two-component composition for forming flexible polyurethane foam according to any one of claims 1 to 7, further comprising a hindered phenol-based antioxidant.

9. 9. The two-component composition for forming flexible polyurethane foams according to claim 8, wherein the mass ratio of the content of the hindered phenol-based antioxidant to the content of the phosphite-based antioxidant in the mixed liquid is 1.1 to 1.

4.

10. 9. The two-component composition for forming flexible polyurethane foams according to claim 8, wherein the mass ratio of the content of the hindered phenol-based antioxidant to the content of the phosphite-based antioxidant in the mixed liquid is 0.4 to 0.

8.

11. A flexible polyurethane foam obtained by reactively foaming a mixed liquid of the first liquid and the second liquid in the two-component composition for forming a flexible polyurethane foam according to any one of claims 1 to 10.

12. The method comprises a step of reacting a polyol component with a polyisocyanate component in the presence of a catalyst, a foam stabilizer, a blowing agent, and a phosphite-based antioxidant to obtain a flexible polyurethane foam, the phosphite antioxidant comprises tetra-(C12-15 alkyl)-4,4'-isopropylidenediphenyl diphosphite; The method for producing a flexible polyurethane foam, wherein the amount of the phosphite-based antioxidant used is 50 to 1100 ppm by mass based on the total amount of the flexible polyurethane foam.

13. 13. The method for producing a flexible polyurethane foam according to claim 12, wherein in the step, a first liquid containing at least a polyol component and a second liquid containing at least a polyisocyanate component are mixed together to react the polyol component with the polyisocyanate component.

14. The method for producing a flexible polyurethane foam according to claim 12, wherein in the step, the first liquid and the second liquid in the two-part composition for forming a flexible polyurethane foam according to any one of claims 1 to 10 are mixed together to react the polyol component with the polyisocyanate component.

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