JP4300570B2 - Method for producing flexible polyurethane foam - Google Patents

Description

  The present invention relates to a flexible polyurethane foam used in a wide range of applications, such as a flexible polyurethane foam in which the foam does not discolor over a long period of time even when exposed to light such as sunlight, especially sanitary products such as napkins and disposable diapers, and shoulder pads. Suitable for flexible polyurethane foam, suitable for clothing such as bra cups.

  Conventionally, flexible polyurethane foams have been widely used due to excellent performance such as flexibility and elasticity, such as cushions and other vehicles, furniture, bra pads, shoulder pads, and other clothing. To produce these, polyurethane diisocyanate (TDI) Aromatic polyisocyanates such as) are used. However, polyurethane foams obtained using aromatic polyisocyanates tend to discolor relatively easily by light such as sunlight. The cause of discoloration, especially yellowing, of polyurethane foam is considered to be due to quinoidization of the benzene ring by ultraviolet rays. As a means for preventing such yellowing, aliphatic polyisocyanate or alicyclic ring is substituted for aromatic polyisocyanate. A flexible polyurethane foam using an aliphatic polyisocyanate has been proposed. For example, Patent Document 1 describes a technique using a special catalyst for an aliphatic or alicyclic polyisocyanate, and Patent Document 2 does not directly bond NCO as an isocyanate to an aromatic ring. It is disclosed that the color stability of polyurethane can be obtained using polyisocyanates. Recently, Patent Document 3 is characterized in that isophorone diisocyanate (IPDI) is used as a polyisocyanate, and a tin-based catalyst and a tertiary amine catalyst, dimethylaminoethyl ether and / or triethylenediamine, are used in combination. A method for producing a flexible polyurethane foam is disclosed. However, in these proposals, (1) when producing polyurethane foams using aliphatic or alicyclic polyisocyanates, it is difficult to balance the reaction, resulting in partial reaction heterogeneity, curing and foaming. Rough cell due to unbalance or the like, a problem of depression, or deformation due to a part having a closed cell state. (2) If no discoloration inhibitor is added, scorch is generated at the time of foaming. (3) There are problems such as being limited to the use of specific alicyclic isocyanates such as IPDI.

JP 50-64389 A JP 52-128997 A Japanese Patent Laid-Open No. 10-36543

  By the production method according to the present invention, a flexible polyurethane foam having a uniform and beautiful cell structure having excellent discoloration resistance against ultraviolet rays, NOx and heat, which has been a problem until now, can be obtained. Furthermore, according to the production method of the present invention, it is possible to obtain a flexible polyurethane foam with little foam discoloration over a long period of time without deteriorating the working environment, and it can be used for a wide range of commercial purposes. I can expect.

  The present invention solves the problems such as discoloration due to ultraviolet rays etc., which is a disadvantage of the conventional flexible polyurethane foam, the uneven cell state due to the above-mentioned reactive imbalance, and the occurrence of scorch, etc. The object is to provide a flexible polyurethane foam that is compatible.

  The present invention has been made as a result of intensive studies to solve the above-mentioned problems and to provide a composition for flexible polyurethane foam having excellent discoloration resistance and having moldability suitable for conventional production conditions. It was issued.

That is, this invention is shown by the following (1)-(6).
(1) A method for producing a flexible polyurethane foam obtained by reaction foaming and curing a mixed liquid of an organic polyisocyanate (A), a polyol (B), a catalyst (C), a foaming agent (D), and a foam stabilizer (E) The organic polyisocyanate component (A) comprises an alcoholic hydroxyl group-containing compound (a-1) and an aliphatic and / or alicyclic diisocyanate (a-2), and the alcoholic hydroxyl group-containing compound (a -1) contains at least a monool compound having 1 to 40 carbon atoms, and the obtained allophanate-modified polyisocyanate composition contains 60% by mass or more of bifunctional components, and has a nominal average functional group number of 2 to 6, A method for producing a flexible polyurethane foam, comprising a polyol (B) having a number average molecular weight of 100 to 20,000.

(2) A method for producing a flexible polyurethane foam obtained by reactive foaming and curing of a mixed solution of an organic polyisocyanate (A), a polyol (B), a catalyst (C), a foaming agent (D) and a foam stabilizer (E) The organic polyisocyanate (A) is an allophanate-modified organic polyisocyanate composition comprising an alcoholic hydroxyl group-containing compound (a-1) and an aliphatic and / or alicyclic diisocyanate (a-2), and a fat. A method for producing a flexible polyurethane foam, comprising a polyol (B) containing an aliphatic and / or alicyclic diisocyanate, having a nominal average functional group number of 2 to 6 and a number average molecular weight of 100 to 20,000.

(3) The alcoholic hydroxyl group-containing compound (a-1) contains at least a monool compound having 1 to 40 carbon atoms, and the obtained allophanate-modified polyisocyanate composition contains 60% by mass or more of a bifunctional component. (2) The method for producing a flexible polyurethane foam according to (2).

(4) The organic polyisocyanate (A) is an alcoholic hydroxyl group-containing compound (a-1) and an aliphatic and / or alicyclic diisocyanate in the presence of a carboxylic acid zirconium salt as an allophanate catalyst (a-3). The method for producing a flexible polyurethane foam according to any one of (1) to (3), comprising an allophanate-modified organic polyisocyanate composition obtained by reacting (a-2).

(5) The method for producing a flexible polyurethane foam according to any one of (1) to (4), wherein the allophanate-modified organic polyisocyanate composition has a content of free hexamethylene diisocyanate of 1% by mass or less. .

(6) The method for producing a flexible polyurethane foam according to any one of (1) to (5), wherein the catalyst (C) uses at least a tolylenediamine salt and dibutyltin acetate.

  The present invention will be described in further detail. The organic polyisocyanate (A) used in the present invention is an allophanate-modified organic polyisocyanate composition comprising an alcoholic hydroxyl group-containing compound (a-1) and an aliphatic and / or alicyclic diisocyanate (a-2). Use things that contain things.

Examples of the alcoholic hydroxyl group-containing compound (a-1) include the following.
Low molecular weight fatty alcohol:
Methanol, ethanol, propanol, isopropanol, isobutanol, pentanol, hexanol and heptanol, allyl alcohol, 2-ethylhexanol, aliphatic alcohol having 10 to 20 carbon atoms, ethanediol, propanediol-1, 2, propanediol 1,3, butanediol-1,2, butanediol-1,3, butanediol-1,4, pentanediol-1,5, neopentyl glycol, hexanediol-1,6, hexanediol-2,5, 3-methylpentanediol-1,5, 2-methyl-2-propylpropanediol-1,3, 2,2-diethylpropanediol-1,3, 2-ethylhexanediol-1,3,2,2, 4-trimethylpentanediol-1,3, trimethyl-he Sundiol-1,6, decanediol-1,10, dodecanediol-1,2,2-butanediol-1,4, 2-methylenepropanediol-1,3, glycerol, butanetriol, 2-hydroxymethyl- 2-methylpropanediol-1,3,1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, pentaerythritol, ethylene glycol monoalkyl- or -aryl ether, propylene glycol monoalkyl ether, diethylene glycol, triethylene Glycol as well as tetraethylene glycol.
Alicyclic alcohol:
Cyclopentanol, cyclohexanol, methylcyclohexanol, trimethylcyclohexanol, 4-tert-butylcyclohexanol, menthol, borneol and isoborneol, 2-hydroxydecalin, 1,2-, 1,3- and 1,4-cyclohexane Diol, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 1,4-bis-hydroxymethylcyclohexane, bis- (4-hydroxycyclohexyl) -methane, 2,2-bis (4- Hydroxycyclohexyl) -propane, 2-methyl-2,4-bis (4-hydroxycyclohexyl) -pentane, furfuryl and tetrahydro-furfuryl alcohol, bis-hydroxymethylnorbornane and dihydroxymethyl-tricyclode Down.
Polymer polyol:
Polythioether polyol, polyacetal polyol, polycarbonate polyol, polyester polyol. In addition, particularly known polyether polyols having 1 to 6 hydroxyl groups can be used, and an epoxide such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin is polymerized, Or starting compounds having reactive hydrogen atoms such as alcohol or phenol, such as water, ethylene glycol, propylene glycol-1,3, propylene glycol-1,2, trimethylolpropane, 4,4'-dihydroxydiphenylpropane, It can be produced optionally in a mixture or sequentially. Condensation products of thiodiglycol itself and / or with other glycols, dicarboxylic acids or formaldehyde may be used as polythioethers. This product is a mixed polythioether, polythioether ester or polythioether polyacetal, depending on the auxiliary components. In the present invention, the alcoholic hydroxyl group-containing compound (a-1) contains at least a monool compound having 1 to 40 carbon atoms in consideration of the viscosity of the organic polyisocyanate (A) and the compatibility with the polyol (B). Is preferred.

  The diisocyanate (a-2) used as a starting material for producing the allophanate-modified organic polyisocyanate composition is not particularly limited as long as it is aliphatic or alicyclic. Examples of aliphatic diisocyanates include hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), butene diisocyanate, 1,3-butadiene-1,4-diisocyanate, octamethylene diisocyanate, and other alicyclic diisocyanates. Examples of these are diisocyanates such as isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate (hydrogenated MDI), hydrogenated xylene diisocyanate (hydrogenated XDI) cyclohexane diisocyanate, methylcyclohexane diisocyanate, and dicyclohexylmethane diisocyanate. Xylene diisocyanate (XDI) and tetramethylxylene diisocyanate (TMXDI) having an aromatic ring but having an isocyanate group not directly bonded to the aromatic ring can also be used in the present invention as belonging to the aliphatic diisocyanate. In the present invention, it is preferable to use HDI in consideration of commercial production. Here, when the working environment is taken into consideration because the vapor pressure of HDI is very low, the free HDI contained in the allophanate-modified organic polyisocyanate composition to be used is adjusted to be 1% by mass or less. Is preferred.

As a catalyst used in the production of an allophanate-modified organic polyisocyanate composition comprising an alcoholic hydroxyl group-containing compound and an aliphatic and / or alicyclic diisocyanate, any known basic compound may be used. Can do. Suitable catalysts in the present invention are the salts of carboxylic acids such as carbonic acid, formic acid, acetic acid, propionic acid and optionally substituted alkali metal, alkaline earth metal, and alkaline earth metal oxides of benzoic acid. In particular, zirconium carboxylate and zirconyl carboxylate salt are most suitable in terms of reactivity and suppression of by-products. Other catalysts include tertiary amines such as trimethylamine, triethylamine, tributylamine, dimethylbenzylamine, 1,4-diazabicyclo-octane, 1,5-diazabicyclo-nonene, tetramethylbutanediamine, tetramethylpropanediamine and bis- N-dimethylaminoethyl ether. Phenolates such as sodium phenolate and alcoholates such as sodium methylate are also suitable catalysts. Aromatic compounds containing nitrogen such as pyridine, mono C ₁ -C ₄ - alkyl pyridine, dimethyl pyridine, N- dimethylamino - pyridine, diethyl pyridine and trimethyl pyridine may also be used. C ₁ -C _4-N-alkyl - pyrrole - pyrroline, - pyrrolidine, pyrazole, - imidazole, - imidazoline, - imidazolidine, 1,2,3-triazole, 1,2,4-triazole, and optionally Also suitable are alkylated pyrimidines, pyridazines, 1,2,3-, 1,2,4-, 1,3,5-triazines, and optionally alkylated quinolines, isoquinolines, quinoxalines and acridines.

  The polyol (B) used in the present invention has a nominal average functional group number of 2 to 6 and a number average molecular weight of 100 to 20,000, and is a polyether polyol or polyester polyol used for a normal flexible polyurethane foam. Can be used. Specifically, ethylene glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, hexanetriol, ethylenediamine, sorbitol, etc. including water as well as water-containing ethylene glycol, diethylene glycol, dipropylene glycol, ethylene glycol, and polypropylene glycol as initiators. A polyether polyol obtained by addition polymerization of oxide (EO), propylene oxide (PO) or both, or a polymer polyol obtained by radical polymerization of acrylonitrile, vinyl or the like to the above polyol, or a modified polyether containing a dispersed urea produced by an amine / isocyanate reaction. Polyol, melamine-modified polyol, and polytetramethylene ether polyol. As the polyester polyol, a condensation polyester polyol of adipic acid and ethylene glycol, butylene glycol, trimethylolpropane, hexanetriol, or the like can be used. In addition, polycarbonate polyol, acrylic polyol, polybutadiene polyol, phosphorus-containing polyol, polyester ether polyol, and the like can be used.

  Preferred in these polyols are polyether polyols having a nominal average functional group number of 2 to 4 and containing equivalent primary and / or secondary hydroxyl groups of 200 to 10,000, or modified polyether polyols thereof, Examples include a condensed or polymerized polyester polyol having an average number of functional groups of 2 to 4 and an equivalent of 200 to 2,000, an equivalent of 200 to 3,000 polytetramethylene ether polyol, an equivalent of 200 to 2,000 of polycarbonate diol, and the like. These may be selected according to the use, and two or more kinds may be mixed and used.

  The catalyst (C) used in the present invention is not particularly limited, and amine catalysts, metal catalysts, amines having an amidino group and derivatives thereof that are usually used in the production of polyurethane foams in the present invention can be used. As the amine-based catalyst, a relatively mild tertiary amine, particularly triethylenediamine, is preferable, but trimethylaminoethylethanolamine, dimethylethylethylethanolamine, dimethylaminomorpholine, triethylamine, 1-isobutyl- 2-methylimidazole, methylmorpholine, ethylmorpholine, diethanolamine, tetramethylhexamethylethylenediamine, dimethylcyclohexylamine, tetramethylpropylenediamine, trimethylaminoethylpiperazine, tetramethylethylenediamine, tris (dimethylaminopropyl) hexahydro-ρ- Triamine, dimethylbenzylamine, dimethylaminoethoxyethanol, dimethylaminohexanol, methylhydroxyl piperazine Etc. can be exemplified. Also, conventionally used amines having an amidino group and derivatives thereof can be used. Examples of the amine having an amidino group and derivatives thereof include 1,8-diazabicyclo (5,4,0) undecene-7, 1,5-diazabicyclo (4,3,0) nonene-5, 6-dibutylamino-1. , 8-diazabicyclo (5,4,0) undecene-7 and the like are preferably used. Examples of the diazabicycloalkanes include 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter also abbreviated as DBU), 1,5-diazabicyclo (4,3,0) nonene-5, 6- Examples thereof include dibutylamino-1,8-diazabicyclo (5,4,0) undecene-7. In addition, alkali metal salts of weak acids, trimerization catalysts, and the like can be used. As the metal catalyst, stannous octate, dibutyltin diacetate, dibutyltin dilaurate, and other relatively mild tin-based catalysts usually used for polyurethane foams are preferably used.

  In the above catalyst, in the present invention, at least a tolylenediamine salt and dibutyltin acetate are used in order to obtain a foam as a stable foam with a good balance of reactivity, uniformity of cells and closed cell properties. Is most suitable.

  As a foaming agent (D) used by this invention, the well-known foaming agent normally used for urethane foam can be used. For example, as a physical blowing agent, halogenated compounds containing so-called alternative chlorofluorocarbons such as hydrocarbon compounds such as pentane and hexane, HCFC-141b, HCFC-123, HCFC-22, HFC-245fa, HFC-365mfc, HFC-134a, etc. A hydrocarbon etc. can be mentioned, and water, an organic acid, etc. can be mentioned as a chemical foaming agent. Further, air, nitrogen gas, carbon dioxide gas or the like can be mixed and dissolved in the stock solution using a gas loading device. These foaming agents can be used in combination of two or more, and the amount used is suitably 1 to 50% by mass of the polyol.

  As the foam stabilizer (E) used in the present invention, L-5309, L-5366, L-5420, L-6202B (manufactured by Nihon Unicar), F-242T, F-303, F-703 (Shin-Etsu Chemical Co., Ltd.) Manufactured), SH-193, PRX-607, SRX-280A, SF-2914, F-122, SF-2962 (manufactured by Toray Silicone), B-8300, B-4113LF (manufactured by Goldschmidt), DC-5169, DC A foam stabilizer used for a polyurethane foam for soft, hard or HR such as -193 (manufactured by Air Products) can be used.

  In the present invention, other conventionally known additives can also be used, if necessary. For example, the excellent discoloration resistance characteristic of the present invention can be further improved by blending an antioxidant or an ultraviolet absorber. Specifically, there are antioxidants such as phenolic antioxidants and phosphorus antioxidants, benzotriazole-based and benzophenol-based ultraviolet absorbers, and the like. In addition, known flame retardants, surfactants, colorants, conductive agents, insulating agents, luminescent agents, antibacterial agents, fragrances and the like can be added.

  In order to produce the flexible polyurethane foam of the present invention using these raw materials, no special technique is required, and the conventional method for producing a flexible polyurethane foam can be applied as it is. That is, generally, the polyisocyanate component, polyol component, catalyst, foaming agent, and other additives that have been stored or prepared in separate containers are put into one reaction container and stirred and mixed so that they are homogeneous. While starting the reaction. The mixture is then poured onto a conveyor lined with molds and bottom paper to cause reaction, foaming and curing. Alternatively, by using a two-component system of polyisocyanate component and polyol component and foaming under pressure with a pressure box and a simple foaming machine, a homogeneous cell-free foam with no cell orientation can be obtained. Can do. In addition, the polyisocyanate component, polyol component, catalyst, and other additives that have been stored or prepared in separate containers are added to one mixing head while mixing an inert gas, and mixed to be homogeneous. Alternatively, a method of casting in a predetermined mold or the like and curing by heating is also possible.

  In this case, the isocyanate index (isocyanate group / active hydrogen group × 100) is preferably from 50 to 150, particularly preferably from 60 to 120. If the index is too low, the foam surface tends to be sticky. In addition, when the index is too high, foaming may not occur, or it may be depressed and a flexible foam may not be obtained.

  When using a formwork, it is desirable that the formwork be adjusted in the range of 30 to 80 ° C in order to obtain a uniform foaming ratio and a sufficient foaming ratio. There is no need for it. A shorter demolding time is preferable from the viewpoint of production efficiency. In the present invention, the mold can be demolded in 3 to 8 minutes after injection, but a demolding time suitable for the conditions of the production facility is arbitrarily set to reduce the defective rate. You can also. The product after demolding can be used as it is, but the cell can be destroyed under compression or reduced pressure by a conventionally known method to stabilize the appearance and dimensions of the product.

  Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

[Production of allophanate-modified polyisocyanate]
Synthesis example 1
A volume of 1 L reactor equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas inlet tube was charged with 975 g of hexamethylene diisocyanate (HDI) and 25 g of methanol, and subjected to urethanization reaction at 90 ° C. for 2 hours. When the reaction product was analyzed by FT-IR, the hydroxyl group had disappeared. Next, 0.2 g of zirconium 2-ethylhexanoate was charged and reacted at 90 ° C. for 3 hours. When the reaction product was analyzed by FT-IR and ¹³ C-NMR, the urethane group had disappeared. Next, 0.1 g of phosphoric acid was added and a stop reaction was performed at 50 ° C. for 1 hour. The isocyanate content of the reaction product after the termination reaction was 42.1%. This reaction product was subjected to thin film distillation at 130 ° C./0.04 kPa, the isocyanate content was 21.1%, the viscosity at 25 ° C. was 118 mPa · s, the free hexamethylene diisocyanate content was 0.1%, the color number Was 20 APHA, and a polyisocyanate P-1 having a bifunctional component of 73% was obtained. When P-1 was analyzed by FT-IR and ¹³ C-NMR, the presence of urethane group was not recognized, and the presence of allophanate group was confirmed. Further, traces of uretdione groups and isocyanurate groups were observed.

Synthesis Examples 2 to 4
Hereinafter, similarly, using HDI and ethanol, in the presence of zirconyl 2-ethylhexanoate, an isocyanate content of 20.0%, a viscosity at 25 ° C. of 98 mPa · s, and a free HDI content of 0.1% Isocyanate P-2, HDI and isopropanol, in the presence of zirconyl 2-ethylhexanoate, the isocyanate content is 19.3%, the viscosity at 25 ° C. is 100 mPa · s, and the free HDI content is 0.1% or less Polyisocyanate P-3, HDI and PP-2000 (poly (oxypropylene) polyol, nominal average functional group number = 2, number average molecular weight = 2,000), and in the presence of zirconyl 2-ethylhexanoate, Polyisocyanate with a content of 6.0%, a viscosity at 25 ° C. of 1,400 mPa · s, and a free HDI content of 0.1% To obtain a P-4.

Example 1
In the reaction vessel, polyester polyol A “Nipporan N-2200” (manufactured by Nippon Polyurethane Industry) having a number average molecular weight of 2,200 and a hydroxyl value (mgKOH / g) of 60 as a polyol component, and an isocyanate “P-1” as an organic polyisocyanate component As a catalyst, 1,8-diazabicyclo-5,4,0-undecene-5 “DBU” (manufactured by San Apro), Stanas octate “Dabco T-9” (manufactured by Air Products), tolylenediamine salt and dibutyltin acetate The mixture of “Dabco DC-2” (manufactured by Air Products) and bis- (dimethylaminoethyl) ether “Toyocat ET” (manufactured by Tosoh) in the mixing ratio of water and L-5309 (manufactured by Nihon Unicar) shown in Table 2 Mixed. With mixing, heat was generated and foamed to form a polyurethane foam. After cooling and curing, the foam was cut out and the properties of the polyurethane foam were evaluated. The evaluation results are shown in Table 2.

Example 2
In the reaction vessel, polyether polyol B “Sanix FA-703” (manufactured by Sanyo Chemical Industries) having a number average molecular weight of 5,000 and a hydroxyl value of 34 (mgKOH / g) as a polyol component, and an isocyanate “P” as an organic polyisocyanate component. Table 1 shows "-1", "diethanolamine" (manufactured by Nippon Shokubai Kagaku) as a crosslinking agent, and dibutyltin dilaurate "Dabco T-12" (manufactured by Air Products), "Dabco DC-2" and "Toyocat ET" as catalysts. Of water and DC-5169 (made by Air Products). With mixing, heat was generated and foamed to form a polyurethane foam. After cooling and curing, the foam was cut out and the properties of the polyurethane foam were evaluated. The evaluation results are shown in Table 2.

Examples 3, 4, 8, 9
In the same manner as in Examples 1 and 2, the isocyanates “P-2” to “ P-4 ” in Table 1 were used as the respective organic polyisocyanate components, and the respective components were mixed at the blending ratios shown in Table 2. . In Example 4 , a DPG solution “TEDA L-33” (manufactured by Tosoh Corporation) of triethylenediamine was used. In Example 8 , polyether polyol C “Exenol 851B” (manufactured by Asahi Glass) having a number average molecular weight of 7,000 and a hydroxyl value of 24 (mgKOH / g) was used as a polyol component. The mixture generated heat and foamed to form a polyurethane foam. After curing, the foam was cut out and the characteristics of the polyurethane foam were evaluated. The evaluation results are shown in Table 2. However, the organic polyisocyanate in Example 8 was prepared by mixing and adjusting the isocyanate “P-4” shown in Table 1 and IPDI at a weight ratio of 30:70. In Example 9, the organic polyisocyanate was used. As an isocyanate “P-3” and an HDI trimer and trimer mixture “Coronate HX” (manufactured by Nippon Polyurethane Industry; NCO% = 21.3%) were mixed and adjusted at a weight ratio of 80:20. I used something.

  According to Table 2, the density of the foam was found to be high or low depending on the type of organic polyisocyanate used and the blending ratio of water, etc., but the reactivity during foam production was practically not a problem. Moreover, the working environment at the time of manufacture and the curing period was good, and unpleasant pungent odors derived from organic polyisocyanates such as HDI were not felt.

  Ultraviolet discoloration was performed by continuously irradiating ultraviolet rays for 40 hours with a fade meter tester and comparing the color difference. As a result, all the foams had good results with a ΔYI value of 5 or less.

  NOx discoloration was carried out in accordance with JIS L0855 “Testing Method for Color Fastness to Nitrogen Oxide”. As a result, in any of the foams, the ΔYI value was a good result of 5 or less.

  Thermal discoloration was allowed to stand in a gear oven at 120 ° C. for 4 hours, and the color difference was compared. As a result, the ΔYI value was 5 or less, which was a favorable result.

Comparative Examples 1-4
Each component described in Table 3 was mixed at each blending ratio in the same manner as in the examples. With mixing, heat was generated and foamed to form a polyurethane foam. After cooling and curing, the foam was cut out and the properties of the polyurethane foam were evaluated. The evaluation results are shown in Table 3. However, in Comparative Example 1, N-methylmorpholine “Caoraiser No. 21” (manufactured by Kao) was used as a catalyst, and tolylene diisocyanate “Coronate T-80” (manufactured by Nippon Polyurethane Industry) was used as an organic polyisocyanate. . In Comparative Example 2, “C-1021” (manufactured by Nippon Polyurethane Industry Co., Ltd.) in which tolylene diisocyanate and polymethylene polyphenyl isocyanate were mixed at a mass ratio of 80:20 was used as the organic isocyanate. In Comparative Example 3, HDI (manufactured by Nippon Polyurethane Industry) was used as the organic polyisocyanate. In Comparative Example 4, “1,4-PG” (manufactured by Idemitsu BASF) was used as polyol D.

  In Comparative Examples 1 and 2, the reactivity at the time of foam production was practically not a problem, but in the case of Comparative Example 3, it took a long time to completely cure the foam surface. The cells were uneven and partially collapsed. In any of the comparative examples, an unpleasant pungent odor or the like derived from organic polyisocyanate such as HDI was strongly felt during the production and curing period. Further, in Comparative Example 4, a high density foam was obtained without feeling unpleasant pungent odor derived from organic polyisocyanate such as HDI, but it was a very hard and inflexible foam. Further, since the foam obtained by heat generation during the production was discolored brown, no discoloration test was performed.

As a result of carrying out the discoloration test in the same manner as in the Examples, significant discoloration was observed in Comparative Examples 1 and 2. In Comparative Example 3, the thermal discoloration was inferior.

Claims (6)

In the method for producing a flexible polyurethane foam obtained by reaction foaming and curing a mixed liquid of an organic polyisocyanate (A), a polyol (B), a catalyst (C), a foaming agent (D), and a foam stabilizer (E), The organic polyisocyanate component (A) comprises an alcoholic hydroxyl group-containing compound (a-1) and an aliphatic and / or alicyclic diisocyanate (a-2), and the alcoholic hydroxyl group-containing compound (a-1) Includes at least a monool compound having 1 to 40 carbon atoms, and the obtained allophanate-modified polyisocyanate composition contains 60% by mass or more of bifunctional components, has a nominal average functional group number of 2 to 6, and a number average molecular weight. A method for producing a flexible polyurethane foam, comprising a polyol (B) having a molecular weight of 100 to 20,000.   In the method for producing a flexible polyurethane foam obtained by reaction foaming and curing a mixed liquid of an organic polyisocyanate (A), a polyol (B), a catalyst (C), a foaming agent (D), and a foam stabilizer (E), The organic polyisocyanate (A) is an allophanate-modified organic polyisocyanate composition comprising an alcoholic hydroxyl group-containing compound (a-1) and an aliphatic and / or alicyclic diisocyanate (a-2), and an aliphatic and A method for producing a flexible polyurethane foam, comprising a polyol (B) containing an alicyclic diisocyanate and having a nominal average functional group number of 2 to 6 and a number average molecular weight of 100 to 20,000. The alcoholic hydroxyl group-containing compound (a-1) contains at least a monool compound having 1 to 40 carbon atoms, and the obtained allophanate-modified polyisocyanate composition contains 60% by mass or more of a bifunctional component. The method for producing a flexible polyurethane foam according to claim 2. The organic polyisocyanate (A) is an alcoholic hydroxyl group-containing compound (a-1) and an aliphatic and / or alicyclic diisocyanate (a-) in the presence of a carboxylic acid zirconium salt as an allophanate catalyst (a-3). The method for producing a flexible polyurethane foam according to any one of claims 1 to 3, comprising an allophanate-modified organic polyisocyanate composition obtained by reacting 2).   The method for producing a flexible polyurethane foam according to any one of claims 1 to 4, wherein the allophanate-modified organic polyisocyanate composition has a free hexamethylene diisocyanate content of 1% by mass or less.   The method for producing a flexible polyurethane foam according to any one of claims 1 to 5, wherein the catalyst (C) uses at least a tolylenediamine salt and dibutyltin acetate.