Polyisocyanate composition for forming flexible polyurethane foam, flexible polyurethane foam using same, and method for producing same

Abstract

To provide a polyisocyanate composition for forming a flexible polyurethane foam capable of forming a flexible polyurethane foam having high hardness and excellent damping characteristics.SOLUTION: A polyisocyanate composition for forming a flexible polyurethane foam, comprising a modified polyphenylene polymethylene polyisocyanate (C) in which a polyphenylene polymethylene polyisocyanate (A) is urethane-modified with a polyol (B), wherein the content of diphenylmethane diisocyanate in the polyphenylene polymethylene polyisocyanate (A) is from 70 to 90 mass%, the average content of ethylene oxide units relative to all alkylene oxide units in the polyol (B) is 65 mass% or less, and the isocyanate group content of the modified polyphenylene polymethylene polyisocyanate (C) is from 20 to 32 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a polyisocyanate composition for forming a flexible polyurethane foam, a flexible polyurethane foam using the same, and a method for producing the same. [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, when used as cushioning for automobile seats and wheelchairs, in addition to the traditional functions required of foams, they are also required to stabilize the seating position while driving in order to improve ride comfort. This stabilization of the seating position is achieved by reducing the vibrations input to the vehicle body while in motion. For example, Japanese Patent Laid-Open Publication No. 2000-33189 (Patent Document 1) discloses a damping seat pad in which a low-breathability film is bonded to the back surface of a seat pad main body made of polyurethane foam. By bonding the low-breathability film to the seat pad main body, this seat pad achieves a significantly lower resonance magnification than the seat pad main body without changing the resonant frequency, thereby improving damping characteristics and achieving a significantly greater damping sensation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-33189 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the seat pad of Patent Document 1, the damping property of the polyurethane foam itself was not considered, and there was still room for further study on the composition of the polyurethane foam. As such, conventional flexible polyurethane foams did not necessarily have sufficient damping properties. Furthermore, conventional flexible polyurethane foams did not necessarily have sufficient hardness.

[0005] Therefore, an object of one aspect of the present disclosure is to provide a polyisocyanate composition for forming a flexible polyurethane foam that can form a flexible polyurethane foam having high hardness and excellent damping properties.An object of another aspect of the present disclosure is to provide a flexible polyurethane foam having high hardness and excellent damping properties and a method for producing the same. [Means for solving the problem]

[0006] The present disclosure provides the following aspects. [1] A polyisocyanate composition for forming a flexible polyurethane foam, comprising a modified polyphenylene polymethylene polyisocyanate (C) in which a polyphenylene polymethylene polyisocyanate (A) is urethane-modified with a polyol (B), the content of diphenylmethane diisocyanate in the polyphenylene polymethylene polyisocyanate (A) is 70 to 90 mass %, the average content of ethylene oxide units relative to all alkylene oxide units in the polyol (B) is 65 mass% or less, A polyisocyanate composition for forming flexible polyurethane foams, wherein the modified polyphenylene polymethylene polyisocyanate (C) has an isocyanate group content of 20 to 32 mass %. [2] the average content of ethylene oxide units relative to all alkylene oxide units in the polyol (B) is 40 mass% or less, The polyisocyanate composition for forming flexible polyurethane foams according to [1], wherein the modified polyphenylene polymethylene polyisocyanate (C) has an isocyanate group content of 23 to 32 mass %. [3] The polyol (B) has an average functionality of 1.0 to 3.5, The polyisocyanate composition for forming flexible polyurethane foams according to [1] or [2], wherein the polyol (B) has an equivalent average molecular weight per functional group of 100 to 3,000. [4] A method for producing a flexible polyurethane foam, comprising reacting a mixed liquid of the polyisocyanate composition for forming a flexible polyurethane foam according to any one of [1] to [3], a polyol (D), a catalyst (E), water (F) as a blowing agent, and a foam stabilizer (G) to form a flexible polyurethane foam. [5] The method for producing a flexible polyurethane foam according to [4], wherein the polyol (D) comprises a polyether polyol having a hydroxyl value of 20 to 40 mgKOH / g and an average functionality of 2 to 4. [6] A flexible polyurethane foam obtained by reacting and foaming a mixed liquid of the polyisocyanate composition for forming a flexible polyurethane foam according to any one of [1] to [3], a polyol (D), a catalyst (E), water (F) as a blowing agent, and a foam stabilizer (G), the flexible polyurethane foam having a logarithmic decrement of 0.50 or more as measured by the following measurement method. [Method for measuring logarithmic decrement] The attenuation test is carried out by changing the following conditions from the method described in JASO B408-89, determining the attenuation waveform at the center of the load on the pressure plate, and calculating the logarithmic attenuation rate based on the obtained attenuation waveform diagram. Pressure plate of damping tester: Oval pressure plate with minor axis 250 mm and major axis 300 mm Test load: 14 kg Pressure plate drop height: 40mm from the foam surface [Effects of the Invention]

[0007] According to one aspect of the present disclosure, it is possible to provide a polyisocyanate composition for forming a flexible polyurethane foam, which is capable of forming a flexible polyurethane foam having high hardness and excellent damping properties. Also, according to another aspect of the present disclosure, it is possible to provide a flexible polyurethane foam having high hardness and excellent damping properties, and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0008] 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.

[0009] 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.

[0010] [Polyisocyanate composition for forming flexible polyurethane foam] A polyisocyanate composition for forming a flexible polyurethane foam according to one embodiment of the present disclosure comprises a modified polyphenylene polymethylene polyisocyanate (C) obtained by urethane-modifying a polyphenylene polymethylene polyisocyanate (A) with a polyol (B), In the polyisocyanate composition for forming a flexible polyurethane foam, the content of diphenylmethane diisocyanate in the polyphenylene polymethylene polyisocyanate (A) is 70 to 90 mass %, the average content of ethylene oxide units relative to all alkylene oxide units in the polyol (B) is 65 mass% or less, The modified polyphenylene polymethylene polyisocyanate (C) has an isocyanate group content of 20 to 32 mass %.

[0011] [[Polyphenylene polymethylene polyisocyanate (A)]] Examples of the polyphenylene polymethylene polyisocyanate (A) include diphenylmethane diisocyanate (MDI mononuclear compound) containing two benzene rings and two isocyanate groups, polynuclear compounds (MDI polynuclear compounds) containing three or more benzene rings and three or more isocyanate groups, and mixtures thereof (polymeric MDI). Examples of MDI mononuclear compounds include 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,2'-diphenylmethane diisocyanate (2,2'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), and mixtures thereof. As a mixture of MDI mononuclear compounds, monomeric MDI containing 4,4'-MDI as the main component is preferred. Here, the term "major component" refers to an MDI mononuclear component that accounts for 50% by mass or more of the MDI mononuclear component mixture, and monomeric MDI may include 2,2'-MDI and 2,4'-MDI. Furthermore, polyphenylene polymethylene polyisocyanate (A) (polymeric MDI (A)) may contain small amounts of impurities that are generally contained in commercially available polyphenylene polymethylene polyisocyanates (polymeric MDI). Examples of impurities contained in commercially available polymeric MDI include isocyanate dimers, methylated polymeric MDI, chlorinated polymeric MDI, carbodiimide compounds, and uretonimine compounds.

[0012] The diphenylmethane diisocyanate content in polyphenylene polymethylene polyisocyanate (A) is the mass content of monomeric MDI in the total polymeric MDI (A), excluding the polyol (B) containing alkylene oxide units from the compositional unit of modified polyphenylene polymethylene polyisocyanate (C) (modified polymeric MDI (C)). This content can be measured using gel permeation chromatography or gas chromatography. Even if the compositional unit before modification is unknown, modified polymeric MDI (C) can be recovered as amines and polyether polyols by Corisch decomposition, allowing the compositional unit before modification to be calculated. Furthermore, when polymeric MDI (A) is prepared by blending various monomeric MDIs or MDI polynuclear compounds, the monomeric MDI content can be calculated if the monomeric MDI content of each raw material is known in advance. The content of monomeric MDI in the total polymeric MDI is preferably 70 to 90 mass %, more preferably 75 to 85 mass %.

[0013] When the content of monomeric MDI in the total polymeric MDI is above the lower limit, interconnected cells are easily formed, and a flexible polyurethane foam with a hardness more suitable for seat cushions, seat backs, and saddles is obtained.On the other hand, when the content of monomeric MDI in the total polymeric MDI is below the upper limit, a flexible polyurethane foam with a hardness more suitable for seat cushions is less likely to deform.

[0014] The sum of the content of 2,2'-diphenylmethane diisocyanate (2,2'-MDI) and the content of 2,4'-diphenylmethane diisocyanate (2,4'-MDI) relative to the total amount of monomeric MDI (isomer ratio in all monomeric MDI) is preferably 10 to 50 mass%, more preferably 20 to 45 mass%.

[0015] When the isomer ratio in all monomeric MDI is at least the above lower limit, the low-temperature storage stability of the resulting polyisocyanate composition for forming flexible polyurethane foam (hereinafter sometimes simply referred to as "polyisocyanate composition") is further improved, reducing the need for constant heating of the isocyanate storage location, piping, and foam molding machine, and also making the moldability of the flexible polyurethane foam more stable and further suppressing foam collapse during foaming, etc. On the other hand, when the isomer ratio in all monomeric MDI is at most the above upper limit, interconnected cells are more likely to be formed, resulting in a flexible polyurethane foam with a hardness more suitable for seat cushions, seat backs, and saddles.

[0016] [[Polyol (B)]] The polyol (B) is used as a modifier for urethane-modifying the polyphenylene polymethylene polyisocyanate (A). The average content of ethylene oxide units relative to all alkylene oxide units in the polyol (B) (average EO content of the polyol (B)) must be 65% by mass or less, and may be 55% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. When the average EO content of the polyol (B) is equal to or less than the upper limit, a flexible polyurethane foam with even better damping properties can be obtained. Furthermore, since the damping properties of the resulting flexible polyurethane foam improve as the average EO content of the polyol (B) decreases, the average EO content of the polyol (B) may be 0% by mass.

[0017] The average functionality of the polyol (B) is typically preferably 1.0 to 8.0, more preferably 1.0 to 3.5. When the average functionality of the polyol (B) is within this range, electrostatic interactions occur between ethylene oxide units or between ethylene oxide units and urethane or urea bonds in the resulting flexible polyurethane foam, further forming a pseudo-crosslinked structure. This makes it easier to achieve a low hysteresis loss rate and high durability even if the impact resilience is low. The average functionality of the polyol refers to a value assuming that the average functionality of the polymerization initiator remains unchanged after polymerization. When multiple polyols are mixed, the number of moles of each polyol is determined from the molecular weight and blend amount of each polyol, and the product of the number of moles and the average functionality of the polymerization initiator is calculated for each polyol. This product is then added up for all polyols, and the product is divided by the sum of the moles of each polyol.

[0018] Furthermore, the equivalent average molecular weight per functional group of polyol (B) is the value obtained by dividing the number average molecular weight of polyol (B) by the average number of functional groups, and is usually preferably 100 to 5000, more preferably 100 to 3000, and even more preferably 200 to 2000. When the equivalent average molecular weight per functional group of polyol (B) is at least the above lower limit, the flexibility of the obtained flexible polyurethane foam tends to be further improved, and the sitting comfort tends to be further improved. On the other hand, when the equivalent average molecular weight per functional group of polyol (B) is at most the above upper limit, the obtained flexible polyurethane foam tends to be even less deformable and has a hardness more suitable for seat cushions, seat backs, and saddles.

[0019] [[Modified polyphenylene polymethylene polyisocyanate (C)]] Modified polyphenylene polymethylene polyisocyanate (C) (modified polymeric MDI (C)) is polyphenylene polymethylene polyisocyanate (A) (polymeric MDI (A)) urethane-modified with polyol (B). Modified polymeric MDI (C), in which polymeric MDI (A) is modified with polyol (B) whose average content of ethylene oxide units is within a specific range, can form a flexible polyurethane foam with excellent damping properties.

[0020] The isocyanate group content (NCO content) of the modified polymeric MDI (C) must be 20 to 32 mass%, preferably 23 to 32 mass%, more preferably 23 to 30 mass%, and even more preferably 23 to 28 mass%. When the NCO content of the modified polymeric MDI (C) is equal to or greater than the lower limit, the viscosity of the modified polymeric MDI (C) is reduced, thereby further improving the flowability of the polyisocyanate composition, further suppressing poor mixing during foaming, and further reducing the burden on the liquid delivery pump of the foam injection machine. On the other hand, when the NCO content of the modified polymeric MDI (C) is equal to or less than the upper limit, a flexible polyurethane foam with even better damping properties can be obtained.

[0021] There are no particular limitations on the method for synthesizing the modified polymeric MDI (C) having such an NCO content, but examples include a method in which the entire amount of polymeric MDI (A) is reacted with the entire amount of polyol (B) to form a prepolymer; and a method in which a portion of polymeric MDI (A) is reacted with polyol (B) to form a prepolymer, and then the remaining polymeric MDI (A) is mixed therewith.

[0022] [Method for producing flexible polyurethane foam] A method for producing a flexible polyurethane foam according to another embodiment of the present disclosure is a method for foaming a mixture of the polyisocyanate composition for forming a flexible polyurethane foam according to one embodiment of the present disclosure, a polyol (D), a catalyst (E), water (F) as a blowing agent, and a foam stabilizer (G) by reacting them.

[0023] [[Polyol (D)]] From the viewpoint of obtaining a flexible polyurethane foam having hardness and flexibility suitable for a flexible foam for vehicle seats, the polyol (D) is preferably a polyether polyol having a hydroxyl value of 20 to 40 mgKOH / g and an average functionality of 2 to 4. When the hydroxyl value of the polyol (D) is equal to or greater than the above lower limit, the viscosity of the mixed liquid decreases, which further improves the flowability and tends to further suppress poor mixing during foaming.

[0024] Examples of such polyether polyols include known polyether polyols obtained by adding alkylene oxides such as ethylene oxide and propylene oxide, or cyclic ethers such as tetrahydrofuran to low-molecular-weight polyols, low-molecular-weight amines, low-molecular-weight amino alcohols, or the like having a number-average molecular weight of less than 700 as an initiator.

[0025] Low molecular weight polyols include water, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, and 2,2,4-trimethyl-1,3-pentanediol. Examples of the low molecular weight amines include aniline, ethylenediamine, propylenediamine, toluenediamine, metaphenylenediamine, diphenylmethanediamine, and xylylenediamine. Examples of the low molecular weight amino alcohols include monoethanolamine, diethanolamine, triethanolamine, and N-methyldiethanolamine.

[0026] In addition, as the polyol (D), a polymer polyol may be used in combination with a polyether polyol. This allows the hardness of the resulting flexible polyurethane foam to be adjusted. Examples of such polymer polyols include those obtained by polymerizing a vinyl monomer in a polyol such as a polyether polyol in the presence of a radical initiator and stably dispersing the polymer. Examples of vinyl monomers include acrylonitrile, styrene, vinylidene chloride, hydroxyalkyl, methacrylate, and alkyl methacrylate. Among these, acrylonitrile and styrene are preferred. Specific examples of such polymer polyols include EL-910 and EL-923 manufactured by AGC Corporation and FA-728R manufactured by Sanyo Chemical Industries, Ltd.

[0027] [[Catalyst (E)]] Examples of the catalyst (E) include various known urethanization catalysts and trimerization catalysts used in the production of flexible polyurethane foams. Examples of urethanization catalysts include tertiary amines such as triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N,N',N',N''-pentamethyldiethylenetriamine, triethylenediamine, bis-(2-dimethylaminoethyl)ether, and 1,8-diaza-bicyclo(5,4,0)undecene-7; reactive tertiary amines such as dimethylethanolamine, N-trioxyethylene-N,N-dimethylamine, and N,N-dimethyl-N-hexanolamine, or organic acid salts thereof; imidazole compounds such as 1-methimidazole, 2-methylimidazole, 1,2-dimethylimidazole, 2,4-dimethylimidazole, and 1-butyl-2-methylimidazole; and organometallic compounds such as stannous octoate, dibutyltin dilaurate, and zinc naphthenate. Examples of trimerization catalysts include 2,4,6-tris(dimethylaminomethyl)phenol, 2,4,6-tris(dialkylaminoalkyl)hexahydro-S-triazine, potassium acetate, and potassium 2-ethylhexanoate. The type and amount of catalyst (E) are not particularly limited as long as they can achieve an appropriate foam cell closed cell ratio and production cycle. From the standpoint of foam odor, etc., the amount of catalyst (E) is preferably 0.1 to 5 parts by mass per 100 parts by mass of polyol (D).

[0028] [[Water (F)]] Water (F) reacts with isocyanate groups to generate carbon dioxide gas. This carbon dioxide gas turns into bubbles in the mixed liquid in the mold, and the urethane reaction of the mixed liquid containing the bubbles proceeds, forming a flexible polyurethane foam. The amount of water (F) is preferably 0.5 to 15 parts by mass per 100 parts by mass of polyol (D). Furthermore, liquefied carbon dioxide gas may be added in an amount of up to 6 parts by mass in addition to water to increase the foaming ratio.

[0029] [Foam stabilizer (G)] The foam stabilizer (G) may be a known organosilicon surfactant used in the production of flexible polyurethane foam. Examples of such organosilicon surfactants include SZ-1327, SZ-1325, SZ-1336, and SZ-3601 manufactured by Dow Corning Toray Co., Ltd., Y-10366J, L-5309J, and L-3639LF manufactured by Momentive Corporation, B-8724LF2 and B-8715LF2 manufactured by Evonik, F-122 manufactured by Shin-Etsu Chemical Co., Ltd., and BL-1107LO manufactured by Menhover. The amount of foam stabilizer (G) is preferably 0.1 to 3 parts by mass per 100 parts by mass of polyol (D).

[0030] (Other additives) If necessary, various additives such as a crosslinking agent, a flame retardant, a plasticizer, an antioxidant, an ultraviolet absorber, a colorant, various fillers, an internal mold release agent, and other processing aids may be blended in. Among these additives, those that do not have an active hydrogen group capable of reacting with isocyanate may be blended in advance with the polyisocyanate composition for forming flexible polyurethane foams.

[0031] (Crosslinking agent) Examples of crosslinking agents include diethanolamine and triethanolamine. The incorporation of a crosslinking agent can improve the molding stability of the flexible polyurethane foam and adjust the foam hardness. The amount of crosslinking agent is preferably 5 parts by mass or less per 100 parts by mass of polyol (D), from the viewpoint of further suppressing excessive closed celling and further suppressing deterioration of mechanical strength due to increased crosslink density.

[0032] The molar ratio (NCO / NCO reactive groups) of all isocyanate groups in the polyisocyanate composition for forming flexible polyurethane foams to all isocyanate reactive groups in the isocyanate-reactive compound containing water during mixing and foaming is preferably 0.7 to 1.4 (isocyanate index (NCO INDEX) = 70 to 140), and more preferably 0.8 to 1.3 (isocyanate index (NCO INDEX) = 80 to 130) to achieve favorable foam durability and molding cycle. When the isocyanate index is equal to or greater than the lower limit, the durability of the resulting flexible polyurethane foam tends to be further improved and excessive closed cell foaming tends to be further suppressed. On the other hand, when the isocyanate index is equal to or less than the upper limit, the urethane reaction is further accelerated, resulting in increased productivity and further suppressing cell collapse during foaming.

[0033] Specifically, in the method for producing a flexible polyurethane foam, a mixed liquid of a polyisocyanate composition for forming a flexible polyurethane foam, a polyol (D), a catalyst (E), water (F) as a blowing agent, and a foam stabilizer (G) is poured into a mold and reacted to cause foaming and curing.

[0034] The mold temperature is usually set to 30 to 80°C, preferably 45 to 70°C. When the mold temperature is set to the lower limit or higher, the urea-forming reaction rate increases, and productivity tends to be further increased. On the other hand, when the mold temperature is set to the upper limit or lower, the urea-forming reaction is suppressed, and cell collapse during foaming is further suppressed, which tends to further improve the durability of the resulting flexible polyurethane foam and the feel of the foam.

[0035] Considering the production cycle of general vehicle seat cushions, seat pads, saddles, etc., the reaction time is preferably 10 minutes or less, more preferably 7 minutes or less.

[0036] When producing flexible molded foams, the above components can be mixed using a high-pressure or low-pressure blowing machine, as in the case of conventional flexible molded foams. The polyisocyanate composition for forming flexible polyurethane foams and the polyol (D) are preferably mixed immediately before foaming. Other components can be blended in advance with the polyisocyanate composition for forming flexible polyurethane foams, or mixed with the polyol (D) to prepare a polyol premix, as long as they do not affect the storage stability of the raw materials or the change in reactivity over time. Such polyisocyanate composition for forming flexible polyurethane foams, polyol (D), or polyol premix can be used immediately after preparation, or stored and used in the required amount. In the case of a foaming device having a structure capable of simultaneously introducing more than two components into the mixing section, the polyisocyanate composition for forming flexible polyurethane foams, polyol (D), catalyst (E), water (F) as a blowing agent, foam stabilizer (G), and various additives can also be introduced into the mixing section individually. The mixing method may be either dynamic mixing, in which mixing is performed in the machine head mixing chamber of the foaming machine, or static mixing, in which mixing is performed in the liquid delivery pipe, or a combination of both. Static mixing is often used to mix gaseous components such as physical blowing agents with liquid components, while dynamic mixing is often used to mix components that can be stably stored as liquids. The foaming device used to produce flexible polyurethane foam is preferably a high-pressure foaming device that does not require solvent cleaning of the mixing section. The mixed liquid obtained by such mixing is discharged into a metal mold, where it is reacted to foam and harden, and then demolded. To facilitate demolding of the resulting flexible polyurethane foam, it is also preferable to pre-coat the mold with a release agent. As the release agent, any release agent commonly used in the molding and processing field may be used. Although the demolded product can be used as is, it is preferable to destroy the foam's cell membrane under compression or reduced pressure using a conventional method to stabilize the product's appearance and dimensions.

[0037] [Soft polyurethane foam] A flexible polyurethane foam according to yet another embodiment of the present disclosure is a foam obtained by reacting and foaming a mixed liquid of the polyisocyanate composition for forming flexible polyurethane foam according to one embodiment of the present disclosure, a polyol (D), a catalyst (E), water (F) as a blowing agent, and a foam stabilizer (G), and has a logarithmic decrement of 0.50 or more, preferably 0.55 or more, and more preferably 0.60 or more, as measured by the following measurement method. By using a flexible polyurethane foam having a logarithmic decrement of at least the above lower limit, it is possible to produce vehicle seat cushions, seat pads, saddles, and the like that stabilize the seating position during driving and provide improved ride comfort.

[0038] [Method for measuring logarithmic decrement] The attenuation test is carried out by changing the following conditions from the method described in JASO B408-89, determining the attenuation waveform at the center of the load on the pressure plate, and calculating the logarithmic attenuation rate based on the obtained attenuation waveform diagram. Pressure plate of damping tester: Oval pressure plate with minor axis 250 mm and major axis 300 mm Test load: 14 kg Pressure plate drop height: 40mm from the foam surface

[0039] A flexible polyurethane foam having such properties can be easily produced by using the polyisocyanate composition for forming a flexible polyurethane foam according to one embodiment of the present disclosure, even when using other commonly available raw materials such as polyols. [Example]

[0040] 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.

[0041] The modifiers used in the examples and comparative examples are as follows:

[0042] (denaturant) PP-1000: Polypropylene glycol (Sanyo Chemical Industries, Ltd. "Sannyx PP-1000", average functionality: 2, number average molecular weight: 1000, average ethylene oxide unit content: 0% by mass). PP-4000: Polypropylene glycol (Sanyo Chemical Industries, Ltd. "Sannyx PP-4000", average functionality: 2, number average molecular weight: 4000, average content of ethylene oxide units: 0% by mass). PP-600: Polypropylene glycol (Sanyo Chemical Industries, Ltd.'s "Sannyx PP-600", average functionality: 2, number average molecular weight: 600, average ethylene oxide unit content: 0% by mass). PP-400: Polypropylene glycol (Sanyo Chemical Industries, Ltd. "Sannyx PP-400", average functionality: 2, number average molecular weight: 400, average content of ethylene oxide units: 0% by mass). MBE-PPG: Polypropylene glycol monobutyl ether (Sigma Aldrich "Poly(propylene glycol) monobutyl ether", average functionality: 1, number average molecular weight: 1000, average content of ethylene oxide units: 0% by mass) FA-909: Polyether polyol ("Sannyx FA-909" manufactured by Sanyo Chemical Industries, Ltd., average functionality: 3, number average molecular weight: 6000, average content of ethylene oxide units: 27% by mass). PEG-1000: Polyethylene glycol ("PEG-1000" manufactured by Sanyo Chemical Industries, Ltd., average number of functional groups: 2, number average molecular weight: 1000, average content of ethylene oxide units: 100% by mass). PEG-600: Polyethylene glycol ("PEG-600" manufactured by Sanyo Chemical Industries, Ltd., average functionality: 2, number average molecular weight: 600, average content of ethylene oxide units: 100% by mass). MPEG1000: Polyethylene glycol methyl ether (Tokyo Chemical Industry Co., Ltd. "Polyethylene Glycol Monomethyl Ether 1000", average functionality: 1, number average molecular weight: 1000, average content of ethylene oxide units: 100% by mass) FA-159: Polyether polyol ("Sannyx FA-159" manufactured by Sanyo Chemical Industries, Ltd., average functionality: 3, number average molecular weight: 7000, average content of ethylene oxide units: 70% by mass).

[0043] Example 1 [Preparation of Polyisocyanate Composition] Monomeric MDI (592 g) with a total content of 2,2'-MDI and 2,4'-MDI (isomer ratio) of 44.9% by mass was charged into a reactor (volume: 1 L) equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube, and the temperature was raised to 75°C. After that, 113 g of polypropylene glycol (Sanyo Chemical Industries, Ltd., "Sannyx PP-1000," average functionality: 2, number-average molecular weight: 1000, average ethylene oxide unit content: 0% by mass) was added as a modifier, and the urethanization reaction was carried out for 2 hours while the mixture was uniformly mixed with a stirring blade while maintaining the temperature at 75°C to 80°C. Next, 295 g of polymeric MDI (containing 39.9% by mass of monomeric MDI and a total content (isomeric ratio) of 2,2'-MDI and 2,4'-MDI in the monomeric MDI of 5.69% by mass) was added, stirred for 30 minutes, and then cooled to room temperature to obtain a polyisocyanate composition containing modified polymeric MDI (NCO content: 28.0% by mass). The total polymeric MDI (= raw monomeric MDI + raw polymeric MDI), which is the sum of the raw monomeric MDI charged before the reaction with the modifier and the raw polymeric MDI charged after the reaction, had a monomeric MDI content of 80.0% by mass, and the total content (isomeric ratio) of 2,2'-MDI and 2,4'-MDI in the total monomeric MDI (= raw monomeric MDI + monomeric MDI in the raw polymeric MDI) was 38.4% by mass.

[0044] The fluidity of the resulting polyisocyanate composition was measured and evaluated by the following method, and the results are shown in Table 1.

[0045] <Liquidity> A polyethylene bag was attached to a smooth acrylic plate without any sagging and placed at a 60° angle from a horizontal stand. One drop of the polyisocyanate composition according to one embodiment of the present disclosure was dropped onto the plate using a pipette, and the time required for the drop to travel 10 cm from the drop point was measured and evaluated according to the following criteria.

[0046] (Evaluation criteria) A: The time required for the movement is less than 180 seconds, which is more preferable in terms of fluidity. B: The time required for the movement is 180 seconds or more and less than 300 seconds, which is preferable in terms of fluidity. C: The time required for the movement is 300 seconds or more, and the fluidity is not favorable.

[0047] [Preparation of Polyol Premix] A mixer (volume: 100 L) equipped with a stirrer was charged with 70 parts by mass of polypropylene glycol (average functionality: 3, number average molecular weight: 6700, average content of ethylene oxide units: 14% by mass, primary terminal ratio: 85% by mass), 1.6 parts by mass of polyether polyol ("Sannyx FA-159" manufactured by Sanyo Chemical Industries, Ltd.), 1.6 parts by mass of polymer polyol (average functionality: 3, number average molecular weight: 5100, average content of ethylene oxide units: 14% by mass, primary terminal ratio: 78% by mass, polymer solids content: 1.0%), and 1.0 parts by mass of ethylene oxide unit (average functionality: 3, number average molecular weight: 5100, average content of ethylene oxide units: 14% by mass, primary terminal ratio: 78% by mass). 30 parts by mass of ethanol (25% by mass), 1.2 parts by mass of sugar alcohol ("Sorbitol S" manufactured by Bussan Food Science Co., Ltd.), 1.5 parts by mass of 2-hydroxymethyltriethylenediamine aqueous solution ("RZETA-50W" manufactured by Tosoh Corporation, amine concentration: 50% by mass) as a catalyst, 1.0 part by mass of silicone foam stabilizer ("BL-1107LO" manufactured by Menhover Co., Ltd.) as a foam stabilizer, and 2.1 parts by mass of water as a blowing agent were charged and mixed uniformly to obtain a polyol premix (hydroxyl value: 227.5 mg KOH / g).

[0048] [Preparation of flexible polyurethane foam] The polyisocyanate composition and polyol premix were each adjusted to a liquid temperature of 25°C ± 1°C and then mixed to achieve an isocyanate index of 90. The resulting mixture was mixed using a mixer at 7000 rpm for 7 seconds, then poured into a mold (300 mm × 300 mm × 100 mm) set at 70°C and allowed to react and foam for 5 minutes. The resulting flexible polyurethane foam was demolded and crushed by roller crushing, after which the total density, 25% compression hardness (25% ILD), and logarithmic decrement were measured using the following methods. The results are shown in Table 1.

[0049] <Total density> The total density (apparent density) of the resulting flexible polyurethane foam was measured according to the method described in JIS K7222:2005.

[0050] <25% compression hardness> Test specimens were prepared from the obtained flexible polyurethane foams according to the method described in JIS K6400-02:2012, and the 25% compression hardness (25% ILD) of these test specimens was measured by the D method.

[0051] <Logarithmic Decay Rate> The resulting flexible polyurethane foam was subjected to a damping test based on the method described in JASO B408-89, except that the damping tester used an elliptical pressure plate with a minor axis of 250 mm and a major axis of 300 mm, and the damping test was carried out under the conditions of a test load of 14 kg and a pressure plate drop height of 40 mm from the foam surface.The damping waveform at the center of the load on the pressure plate was obtained, and the logarithmic damping rate was calculated based on the obtained damping waveform diagram.

[0052] (Examples 2 to 13 and Comparative Examples 1 to 7) [Preparation of Polyisocyanate Composition] Polyisocyanate compositions containing modified polymeric MDI were obtained in the same manner as in Example 1, except that the modifiers shown in Tables 1 to 3 were used and the blending amounts of each component were changed to those shown in Tables 1 to 3. The NCO content of the modified polymeric MDI in the resulting polyisocyanate compositions and the composition of the total polymeric MDI (monomeric MDI content and isomer ratio in the total monomeric MDI), which is the sum of the raw material monomeric MDI charged before the reaction with the modifier and the raw material polymeric MDI charged after the reaction, are shown in Tables 1 to 3. The viscosities at 25°C of the resulting polyisocyanate compositions were 252 mPa·s (Example 7), 444 mPa·s (Example 8), 109 mPa·s (Example 13), 55 mPa·s (Comparative Example 1), 1560 mPa·s (Comparative Example 3), and 149 mPa·s (Comparative Example 7).

[0053] Furthermore, the fluidity of the resulting polyisocyanate composition was measured and evaluated in the same manner as in Example 1. The results are shown in Tables 1 to 3.

[0054] [Preparation of flexible polyurethane foam] Flexible polyurethane foams were produced in the same manner as in Example 1, except that the obtained polyisocyanate composition and a polyol premix prepared in the same manner as in Example 1 were mixed so as to obtain the isocyanate index shown in Tables 1 to 3. The total density, 25% compression hardness (25% ILD), and logarithmic decrement of the obtained flexible polyurethane foams were measured in the same manner as in Example 1. The results are shown in Tables 1 to 3.

[0055] Example 14 [Preparation of Polyisocyanate Composition] A polyisocyanate composition containing polymeric MDI modified with PP-1000 was prepared in the same manner as in Example 1. In addition, a polyisocyanate composition containing polymeric MDI modified with PEG-1000 was prepared in the same manner as in Example 1, except that polyethylene glycol ("PEG-1000" manufactured by Sanyo Chemical Industries, Ltd., average functionality: 2, number average molecular weight: 1000, average content of ethylene oxide units: 100% by mass) (113 g) was used instead of polypropylene glycol as the modifier.

[0056] To the resulting polyisocyanate composition (400 g) containing PEG-1000-modified polymeric MDI, 600 g of a polyisocyanate composition containing PP-1000-modified polymeric MDI was added, and the mixture was stirred for 30 minutes to obtain a polyisocyanate composition containing modified polymeric MDI with an average ethylene oxide unit content of 40 mass%. Table 2 shows the NCO content of the modified polymeric MDI in the resulting polyisocyanate composition, as well as the composition of the total polymeric MDI (monomeric MDI content and isomer ratio in the total monomeric MDI), which is the sum of the raw material monomeric MDI charged before and after the reaction with the modifier. The amounts of raw material monomeric MDI, raw material polymeric MDI, and modifier in Table 2 are converted into the amounts of polyisocyanate composition containing PP-1000-modified polymeric MDI and polyisocyanate composition containing PEG-1000-modified polymeric MDI used to prepare the target polyisocyanate composition. The viscosity of the resulting polyisocyanate composition at 25°C was 86 mPa s.

[0057] The fluidity of the resulting polyisocyanate composition was measured in the same manner as in Example 1. The results are shown in Table 2.

[0058] [Preparation of flexible polyurethane foam] A flexible polyurethane foam was produced in the same manner as in Example 1, except that the obtained polyisocyanate composition and a polyol premix prepared in the same manner as in Example 1 were mixed so that the isocyanate index was 95. The total density, 25% compression hardness (25% ILD), and logarithmic decrement of the obtained flexible polyurethane foam were measured in the same manner as in Example 1. The results are shown in Table 2.

[0059] (Example 15 and Comparative Example 8) [Preparation of Polyisocyanate Composition] The amount of the polyisocyanate composition containing PEG-1000-modified polymeric MDI was changed to 600 g in Example 15 and 700 g in Comparative Example 8, and the amount of the polyisocyanate composition containing PP-1000-modified polymeric MDI was changed to 400 g in Example 15 and 300 g in Comparative Example 8. The procedure was the same as in Example 14, except that the average content of ethylene oxide units in the modifier was 60 mass% in Example 15 and 70 mass% in Comparative Example 8. The NCO content of the modified polymeric MDI in the resulting polyisocyanate composition and the composition of the total polymeric MDI (monomeric MDI content and isomer ratio in total monomeric MDI), which is the sum of the raw material monomeric MDI charged before and after the reaction with the modifier, are shown in Tables 2 and 3. The amounts of raw material monomeric MDI, raw material polymeric MDI, and modifiers in Tables 2 and 3 are calculated based on the amounts of the polyisocyanate composition containing the PP-1000-modified polymeric MDI and the polyisocyanate composition containing the PEG-1000-modified polymeric MDI used to prepare the target polyisocyanate composition.

[0060] Furthermore, the fluidity of the resulting polyisocyanate composition was measured and evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0061] [Preparation of flexible polyurethane foam] Flexible polyurethane foams were produced in the same manner as in Example 1, except that the obtained polyisocyanate composition and a polyol premix prepared in the same manner as in Example 1 were mixed so as to obtain the isocyanate index shown in Tables 2 and 3. The total density, 25% compression hardness (25% ILD), and logarithmic decrement of the obtained flexible polyurethane foams were measured in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

Claims

1. A polyisocyanate composition for forming a flexible polyurethane foam, comprising a modified polyphenylene polymethylene polyisocyanate (C) obtained by urethane-modifying a polyphenylene polymethylene polyisocyanate (A) with a polyol (B), the content of diphenylmethane diisocyanate in the polyphenylene polymethylene polyisocyanate (A) is 70 to 90 mass %, the average content of ethylene oxide units relative to all alkylene oxide units in the polyol (B) is 65 mass% or less, A polyisocyanate composition for forming flexible polyurethane foams, wherein the modified polyphenylene polymethylene polyisocyanate (C) has an isocyanate group content of 20 to 32 mass %.

2. the average content of ethylene oxide units relative to all alkylene oxide units in the polyol (B) is 40 mass% or less, 2. The polyisocyanate composition for forming flexible polyurethane foams according to claim 1, wherein the modified polyphenylene polymethylene polyisocyanate (C) has an isocyanate group content of 23 to 32 mass%.

3. the polyol (B) has an average functionality of 1.0 to 3.5; 2. The polyisocyanate composition for forming flexible polyurethane foams according to claim 1, wherein the polyol (B) has an equivalent average molecular weight per functional group of 100 to 3,000.

4. A method for producing a flexible polyurethane foam, comprising reacting a mixed liquid of the polyisocyanate composition for forming a flexible polyurethane foam according to any one of claims 1 to 3, a polyol (D), a catalyst (E), water (F) as a blowing agent, and a foam stabilizer (G) to foam the mixed liquid.

5. The method for producing a flexible polyurethane foam according to claim 4, wherein the polyol (D) comprises a polyether polyol having a hydroxyl value of 20 to 40 mgKOH / g and an average functionality of 2 to 4.

6. A flexible polyurethane foam obtained by reacting and foaming a mixed liquid of the polyisocyanate composition for forming a flexible polyurethane foam according to any one of claims 1 to 3, a polyol (D), a catalyst (E), water (F) as a blowing agent, and a foam stabilizer (G), wherein the logarithmic decrement measured by the following measurement method is 0.50 or more. [Method for measuring logarithmic decrement] A damping test is carried out by changing the following conditions from the method described in JASO B408-89, and the damping waveform at the center of the load on the pressure plate is determined. The logarithmic damping rate is calculated based on the obtained damping waveform diagram. Pressure plate of damping tester: oval pressure plate with minor axis 250 mm and major axis 300 mm Test load: 14 kg Pressure plate drop height: 40 mm from the foam surface

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