JP2005232466A - Preparation of high elasticity polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high elasticity polyurethane foam with improved comfortableness and to provide a method for production of the same with improved moldability. <P>SOLUTION: The invention relates to the method for production of the high elasticity polyurethane foam by reacting a high molecular weight active hydrogen compound having two or more active hydrogen functional groups reactive to an isocyanate group with a polyisocyanate compound in the presence of a catalyst and a blowing agent, wherein the high molecular weight active hydrogen compound is a mixture of the polyols comprising (A) a polyoxyalkylene polyol obtained by ring-opening polymerization of a cyclic ether in the presence of an initiator using a sodium or potassium based catalyst and (B) a polyoxyalkylene polyol obtained by ring-opening polymerization of a cyclic ether in the presence of an initiator using a multi-metal cyanide complex or a cesium catalyst, wherein the mixing ratio (A)/(B) (weight ratio) is 5/95-90/10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a highly elastic polyurethane foam.

  In recent years, various studies have been newly made to improve the characteristics of polyurethane elastic foam. For example, in order to improve the ride comfort of a seat cushion with the upgrading of automobiles and the like, improvements in resilience, durability, and vibration characteristics are desired. Regarding the vibration characteristics, the relationship between body vibration and human beings is not uniform, but taking a large attenuation in a frequency range particularly sensitive to humans (for example, 4-8 Hz or 6-20 Hz) can improve riding comfort. It is proposed to be effective.

  In order to improve these properties, it has been considered effective to produce a seat cushion using a polyoxyalkylene polyol having a higher molecular weight than that conventionally produced.

  In general, polyoxyalkylene polyols used as raw materials for polyurethane are obtained by ring-opening polymerization of alkylene oxides such as propylene oxide on initiators such as polyhydric alcohols using sodium or potassium-based catalysts such as sodium hydroxide and potassium hydroxide. Manufactured.

  In this production method, a monool having an unsaturated group is produced as a by-product, and the amount of the unsaturated monool produced increases as the molecular weight of the polyoxyalkylene polyol increases (decrease in the hydroxyl value). In a polyoxyalkylene polyol having a hydroxyl value of about 56, which is widely used as a raw material for polyurethane elastic foam, the presence of this unsaturated monool was not a significant amount. However, the presence of this unsaturated monool may be a problem in low-hydroxyl polyoxyalkylene polyols having an increased molecular weight.

  For example, in a polyoxyalkylene polyol having a hydroxyl value of about 34, the total degree of unsaturation is usually 0.1 meq / g or more. Even when an elastic foam is produced using a polyoxyalkylene polyol having a high degree of total unsaturation, problems such as a decrease in hardness, a decrease in impact resilience, a deterioration in compression set, and a decrease in the curing property during foam molding occur. Furthermore, it was practically impossible to produce a polyoxyalkylene polyol having a low hydroxyl value using a sodium or potassium-based catalyst because the total unsaturation level was extremely high.

  For the purpose of improving riding comfort performance, it is possible to produce a polyurethane elastic foam using a high molecular weight polyoxyalkylene polyol having a low total unsaturation synthesized by ring-opening polymerization of alkylene oxide using a double metal cyanide complex as a catalyst. JP-A-3-45613. Further, as a method for reducing the total unsaturation degree of the high molecular weight polyoxyalkylene polyol, a method using cesium hydroxide as a polymerization catalyst is described in US Pat. No. 3,393,243.

Japanese Patent Laid-Open No. 3-45613 US Pat. No. 3,393,243

  However, due to the recent increase in size and shape of seat cushions, in addition to ride comfort performance, improvements in performance called formability such as fluidity, air void resistance, and connectivity have been required.

  The present invention is the next invention which has solved the above-mentioned problems. That is, in producing a highly elastic polyurethane foam by reacting a high molecular weight active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group and a polyisocyanate compound in the presence of a catalyst and a foaming agent, An active hydrogen compound is a polyoxyalkylene polyol (A) obtained by ring-opening polymerization of a cyclic ether using a sodium or potassium catalyst in the presence of an initiator, and a composite metal cyanide complex catalyst or a cesium catalyst in the presence of an initiator. The polyoxyalkylene polyol (B) obtained by ring-opening polymerization of cyclic ether using (A) / (B) (weight ratio) is a mixed polyol formed by mixing at 10/90 to 95/5. This is a method for producing a highly elastic polyurethane foam.

  The highly elastic polyurethane foam produced by the production method of the present invention has the effect of greatly improving ride comfort performance and moldability.

  In recent years, when unprecedented high molecular weight polyoxyalkylene polyols synthesized with a composite metal cyanide complex or a cesium hydroxide catalyst and used as a raw material for seat cushion molding, the comfort of seat cushions It became clear that was improved.

  Furthermore, the present inventor can reduce the viscosity of the reaction stock solution by blending this polyol with a polyoxyalkylene polyol synthesized using a sodium or potassium catalyst, which is usually commercially available, at a specific ratio. It was found that the fluidity is greatly improved. The use of this high molecular weight polyoxyalkylene polyol has dramatically improved seat cushions with large and complex shapes (air voids, shrinks, etc.) while maintaining ride comfort. I found out that

  Polyoxyalkylene polyol obtained by ring-opening polymerization of cyclic ether using sodium or potassium-based catalyst in the present invention, and polyoxyalkylene polyol obtained by ring-opening polymerization of cyclic ether using cesium-based catalyst or double metal cyanide complex catalyst May be a mixture of two or more, and the average number of hydroxyl groups and the range of hydroxyl values in that case are as described above.

  The cyclic ether is preferably an alkylene oxide having 2 or more carbon atoms, and specific examples include ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, and styrene oxide. In particular, a combination of ethylene oxide and at least one selected from propylene oxide, 1,2-butylene oxide, and 2,3-butylene oxide is preferable.

  The polyoxyalkylene polyol of the present invention preferably contains an oxyethylene group. A polyoxyalkylene polyol containing an oxyethylene group at the terminal can be obtained by adding ethylene oxide after adding an alkylene oxide having 3 or more carbon atoms such as propylene oxide or 1,2-butylene oxide to a polyvalent initiator.

  Also, polyoxyalkylene polyols containing oxyethylene groups inside can be obtained by adding ethylene oxide and alkylene oxide having 3 or more carbon atoms to the polyvalent initiator sequentially or mixed, and adding ethylene oxide at the final stage. It is done.

  The content of oxyethylene groups is preferably 3% by weight or more, particularly 5% by weight or more. The total oxyethylene group content in the polyoxyalkylene polyol including the oxyethylene groups present at the terminals and inside is preferably 25% by weight or less. In that case, most of the oxyethylene group is preferably present at the end of the molecular chain.

  Examples of the polyvalent initiator used in the production of the polyoxyalkylene polyol include polyhydric alcohol, polyhydric phenol, polyamine, and alkanolamine. The number of active hydrogens in the initiator is preferably 2-6, and the number of hydroxyl groups in the polyoxyalkylene polyol produced from such an initiator is 2-6.

  For example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, dextrose, sucrose, bisphenol A, ethylenediamine, and polyoxyalkylene polyol having a lower molecular weight than the target product obtained by adding an alkylene oxide thereto.

  These initiators may be used alone or in combination of two or more. A particularly preferred polyvalent initiator is a polyhydric alcohol.

  Examples of the sodium or potassium-based catalyst used in the production of the polyol (A) in the present invention include sodium metal, potassium metal, sodium methoxide, sodium ethoxide, sodium propoxide, potassium methoxide, potassium ethoxide, potassium propoxide, and the like. Sodium or potassium alkoxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like.

  The hydroxyl value of the polyol (A) is preferably 20-60.

  Examples of the cesium catalyst used in the production of the polyol (B) in the present invention include those selected from cesium alkoxides such as cesium metal, cesium methoxide, cesium ethoxide, cesium propoxide, cesium hydroxide and cesium carbonate. What is made into a component is preferable. Those mainly composed of cesium hydroxide are particularly preferred.

  As the double metal cyanide complex, a complex mainly composed of zinc hexacyanocobaltate is preferable, and its ether and / or alcohol complex is preferable. The composition essentially described in JP-B-46-27250 can be used. As the ether, ethylene glycol dimethyl ether (glyme), diethylene glycol dimethyl ether (diglyme), and the like are preferable. Among them, glyme is preferable because of handling during production of the complex. As the alcohol, t-butanol described in JP-A-4-145123 is preferable.

  The polyol (B) is preferably a polyoxyalkylene polyol obtained by ring-opening polymerization of a cyclic ether using a cesium catalyst.

  The hydroxyl value of the polyol (B) is preferably 5 to 35. The total unsaturation degree of the polyol (B) is preferably 0.05 meq / g or less.

  The polyol (A) and the polyol (B) are mixed in a ratio (A) / (B) (weight ratio) of 5/95 to 90/10. The total unsaturation degree of the mixed polyol obtained by mixing the polyol (A) and the polyol (B) is preferably 0.08 meq / g or less.

  The mixed polyol may be a polymer-dispersed polyol containing polymer fine particles.

  The polymer-dispersed polyol is a dispersion in which polymer fine particles are stably dispersed in a polyoxyalkylene polyol matrix, and examples of the polymer include addition polymerization type polymers and condensation polymerization type polymers.

  Polymer-dispersed polyols whose matrix is a conventional polyol are known and widely used as polyols for polyurethane elastic foam. The polymer-dispersed polyol in the present invention can be produced by a conventional method using the polyol (A), polyol (B) or mixed polyol as a matrix.

  The polymer fine particles in the polymer-dispersed polyol are composed of addition polymerization type polymers such as homopolymers and copolymers of acrylonitrile, styrene, methacrylate, acrylate, and other vinyl monomers, and polycondensation polymers such as polyester, polyurea, polyurethane, and melamine resin. . Due to the presence of the polymer fine particles, the hydroxyl value of the whole polymer-dispersed polyol is generally lower than the hydroxyl value of the matrix polyol.

  The content of the polymer fine particles in the mixed polyol is usually preferably 50% by weight or less. The amount of the polymer fine particles need not be particularly large, and if it is too large, it is not inconvenient except for economical reasons. In many cases, 3 to 35% by weight is preferred. The presence of fine polymer particles in the polyol is not essential, but if present, it is effective for improving the hardness, breathability and other physical properties of the foam.

  As high molecular weight active hydrogen compounds other than the above mixed polyols, high molecular weight polyamines having two or more primary amino groups or secondary amino groups, and high molecular weight compounds having one or more primary amino groups or secondary amino groups and one or more hydroxyl groups Can be used in combination.

  These high molecular weight active hydrogen compounds have a molecular weight per functional group of 400 or more, particularly 800 or more, and the number of functional groups per molecule is preferably 2-8. The molecular weight per functional group is preferably 10,000 or less.

  Examples of such compounds include compounds obtained by converting some or all of the hydroxyl groups of the polyoxyalkylene polyol as described above to amino groups, and polyoxyalkylene polyols as described above and an excess equivalent amount of polyisocyanate compound. There is a compound obtained by hydrolyzing an isocyanate group of a prepolymer having an isocyanate group at the terminal obtained by reaction and converting it to an amino group.

  In addition, when using the high molecular weight active hydrogen compound that can be used in combination with the mixed polyol, the amount used is preferably 40% by weight or less, particularly preferably 20% by weight or less, based on the total of both.

  In the present invention, a crosslinking agent may be used as necessary. The crosslinking agent is a compound having two or more functional groups selected from a hydroxyl group, a primary amino group and a secondary amino group, a molecular weight of 1800 or less, and an active hydrogen-containing group number of 2 to 8, and at least one compound Is preferably used. Two or more crosslinking agents may be used in combination.

  The crosslinking agent having a hydroxyl group preferably has 2 to 8 hydroxyl groups. There are polyols such as a polyhydric alcohol, a low molecular weight polyoxyalkylene polyol obtained by adding an alkylene oxide to a polyhydric alcohol, or a polyol having a tertiary amino group.

  Specific examples include, but are not limited to, the following exemplified compounds. Ethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, monoethanolamine, diethanolamine, triethanolamine, N-alkyldiethanol, bisphenol A-alkylene Oxide adduct, glycerin-alkylene oxide adduct, trimethylolpropane-alkylene oxide adduct, pentaerythritol-alkylene oxide adduct, sorbitol-alkylene oxide adduct, sucrose-alkylene oxide adduct, aliphatic amine-alkylene oxide adduct , Alicyclic amine-alkylene oxide adduct, heterocyclic polyamine-alkylene oxide adduct, aromatic amine-alkylene oxide Sid adduct, and the like.

  Heterocyclic polyamine-alkylene oxide adducts are piperazine, 2-methylpiperazine, 2-ethylpiperazine, 2-butylpiperazine, 2-hexylpiperazine, 2,5-, 2,6-, 2,3- or 2,2 -C-lower alkyl substituted piperazine such as dimethylpiperazine, 2,3,5,6- or 2,2,5,5-tetramethylpiperazine, aminoalkyl substituted piperazine such as 1- (2-aminoethyl) piperazine, etc. It can be obtained by adding alkylene oxide to

  Examples of the amine-based crosslinking agent having a primary amino group or a secondary amino group include aromatic polyamines, aliphatic polyamines, and alicyclic polyamines.

  The aromatic polyamine is preferably an aromatic diamine. As the aromatic diamine, an aromatic diamine having one or more substituents selected from an alkyl group, a cycloalkyl group, an alkoxy group, an alkylthio group, and an electron-withdrawing group in an aromatic nucleus to which an amino group is bonded is preferable. In particular, a diaminobenzene derivative is preferred. It is preferable that 2 to 4 of the substituents excluding the electron-withdrawing group are bonded to the aromatic nucleus to which the amino group is bonded, and particularly one or more, preferably all, of the ortho position with respect to the binding site of the amino group. Bonding is preferred.

  It is preferable that one or two electron-withdrawing groups are bonded to the aromatic nucleus to which the amino group is bonded. An electron-withdrawing group and another substituent may be bonded to one aromatic nucleus. The alkyl group, alkoxy group, and alkylthio group preferably have 4 or less carbon atoms, and the cycloalkyl group is preferably a cyclohexyl group. As the electron withdrawing group, a halogen atom, a trihalomethyl group, a nitro group, a cyano group, an alkoxycarbonyl group, and the like are preferable, and a chlorine atom, a trifluoromethyl group, and a nitro group are particularly preferable.

  Aliphatic polyamines include diaminoalkanes having 6 or less carbon atoms, polyalkylene polyamines, polyamines obtained by converting some or all of the hydroxyl groups of low molecular weight polyoxyalkylene polyols to amino groups, and the like. Furthermore, polyamines having aromatic nuclei such as aromatic compounds having two or more aminoalkyl groups, aromatic compounds having two or more aminoalkyl groups in total, and those aromatic compounds having the above substituents are also used. it can. Alicyclic polyamines include cycloalkanes having two or more amino groups and / or aminoalkyl groups.

  Specific examples of the amine chain extender are shown below, but are not limited thereto. Particularly preferably, diethyltoluenediamine [that is, one or a mixture of 1-methyl-3,5-diethyl-2,4 (or 2,6) -diaminobenzene], dimethylthiotoluenediamine, monochlorodiaminobenzene, trifluoro Diaminobenzene derivatives such as methyldiaminobenzene.

  1-methyl-3,5-diethyl-2,4 (or 2,6) -diaminobenzene (DETDA), 2-chloro-p-phenylenediamine (CPA), 1-methyl-3,5-dimethylthio-2, 4 (or 2,6) -diaminobenzene, 1-trifluoromethyl-3,5-diaminobenzene, 1-trifluoromethyl-4-chloro-3,5-diaminobenzene, 2,4-toluenediamine, 2, 6-toluenediamine, bis (3,5-dimethyl-4-aminophenyl) methane, 4,4-diaminodiphenylmethane, ethylenediamine, m-xylenediamine, 1,4-diaminohexane, 1,3-bis (aminomethyl) Cyclohexane, isophoronediamine.

  Examples of the polyisocyanate compound include aromatic, alicyclic or aliphatic polyisocyanates having two or more isocyanate groups, mixtures of two or more of them, and modified polyisocyanates obtained by modifying them. Specifically, for example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (common name: crude MDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HMDI). And the like, and their prepolymer-type modified products, nurate-modified products, urea-modified products, and carbodiimide-modified products.

  In the present invention, it is preferable to use one or more foaming agents selected from water and an inert gas as the foaming agent. Specific examples of the inert gas include air and nitrogen. The amount of the foaming agent used is not particularly limited. When only water is used, the amount is suitably 10 parts by weight, particularly 0.1 to 8 parts by weight, based on 100 parts by weight of the high molecular weight active hydrogen compound. Other foaming agents can also be used in an appropriate amount according to demands such as the expansion ratio.

  When reacting a polyol and a polyisocyanate compound, it is usually necessary to use a catalyst. In recent years, in order to prevent the fogging phenomenon (fogging) of automobile glass, hydroxylation or amination is performed so that a part of the structure of amine compound, organometallic compound or amine compound with low sublimation property reacts with isocyanate. In some cases, the minimum required amount is used. In addition, a multimerization catalyst for reacting isocyanate groups such as a carboxylic acid metal salt is used depending on the purpose.

  Examples of the reactive amine catalyst include dimethylethanolamine, trimethylaminoethylethanolamine, dimethylaminoethoxyethoxyethanol and the like.

  The amount of the amine compound catalyst used is preferably up to 1.0 part by weight, particularly 0.05 to 1.0 part by weight, based on 100 parts by weight of the high molecular weight active hydrogen compound.

  Examples of organometallic compound catalysts include organotin compounds, organobismuth compounds, organolead compounds, and organozinc compounds.

  For example, di-n-butyltin oxide, di-n-butyltin dilaurate, di-n-butyltin, di-n-butyltin diacetate, di-n-octyltin oxide, di-n-octyltin dilaurate, monobutyltin trichloride , Di-n-butyltin dialkyl mercaptan, di-n-octyltin dialkyl mercaptan, and the like. The amount of the organometallic compound catalyst used is preferably up to 1.0 part by weight, particularly preferably 0.005 to 1.0 part by weight, per 100 parts by weight of the high molecular weight active hydrogen compound.

  In addition, foam stabilizers are often used to form good bubbles. Examples of the foam stabilizer include a silicone foam stabilizer and a fluorine-containing compound foam stabilizer. In addition, examples of a compounding agent that can be optionally used include a filler, a stabilizer, a colorant, a flame retardant, and a foam breaker.

  High elastic polyurethane foam is formed by a method in which a reactive mixture is directly injected into a mold using a low-pressure foaming machine or a high-pressure foaming machine (that is, a reaction injection molding method) or a method in which the reactive mixture is poured into an open mold. Is preferably carried out. The high-pressure foaming machine is preferably of a type in which two ordinary liquids are mixed, one of which is a polyisocyanate compound, and the other liquid is a mixture of all raw materials other than the polyisocyanate compound. In some cases, a reactive mixture may be formed and injected with a total of three components including a catalyst or a foam breaker (usually used after being dispersed or dissolved in some high molecular weight polyols).

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto (parts indicate parts by weight).

  Polyoxyalkylene polyols (a) to (Examples 1 to 11, 18 to 28, 35 to 40, 46 to 52) and comparative examples (Examples 12 to 17, 29 to 34, 41 to 45, 53) Table 1 shows the molecular weight, the number of hydroxyl groups, the oxyethylene (EO) group content (% by weight), the polymerization catalyst, the hydroxyl value (mgKOH / g), and the degree of unsaturation (meq / g). Those obtained by mixing AC with the composition shown in Table 2 were designated as polyols a to s. Table 3 shows prescription components other than the polyol.

  (Examples 1 to 17) 70 parts of polyols a to s shown in Tables 4 to 5, 30 parts of polyol y, 1.0 part of foam stabilizer v, 3.4 parts of foaming agent x, amine catalyst A mixture of 0.33 part of t and 0.06 part of amine catalyst u was used as a polyol solution. The polyol liquid was put into one raw material tank of a reaction injection molding apparatus (high pressure foaming machine), and the liquid temperature was adjusted to 25 to 30 ° C. Moreover, polyisocyanate (alpha) was put into the other raw material tank of the reaction injection molding apparatus as a polyisocyanate liquid, and the liquid temperature was adjusted to 25-30 degreeC.

Both were mixed and injected at a ratio of the isocyanate index (index) shown in the table. The isocyanate index refers to the number of equivalents of isocyanate compound relative to 100 equivalents of all active hydrogen compounds. The injection conditions were an injection pressure of 140 kg / cm ² and an injection amount of 300 g / second. A mold having an inner dimension of 400 mm × 400 mm × 100 mm (t) was used as the mold, and the mold temperature was adjusted to 58 to 62 ° C. Demolding from the mold was performed 5 minutes after the raw material injection.

Tables 4 to 5 show the foam physical properties, vibration characteristics, and moldability of the obtained highly elastic polyurethane foam. Foam physical properties are total density (unit: kg / m ³ ), 25% ILD (unit: kg / 314 cm ² ), compression set (%), wet heat compression set (%), rebound resilience (%) and breathability. (Ft ³ / min) was evaluated. For the vibration characteristics, a transmission rate of 6 Hz and a resonance frequency (unit: Hz) were evaluated. As for moldability, fluidity and crushing properties were evaluated. In the evaluation of fluidity, ◎ was good, ○ was slightly good, and Δ was poor, and the crushing property evaluation was ◎, good, ○ was slightly good, and Δ was bad.

  Examples 18 to 34 65 parts of the polyols a to s shown in Tables 6 to 7, 35 parts of polyol y, 1.0 part of foam stabilizer v, 3.25 parts of foaming agent x, amine catalyst A mixture of 0.35 part of t and 0.04 part of amine catalyst u was used as a polyol liquid, and the same procedure as in Examples 1 to 16 except that polyisocyanate β was used as the polyisocyanate liquid. The isocyanate index is shown in Tables 6-7. Tables 6 to 7 show the foam physical properties, vibration characteristics, and moldability of the obtained foams.

  (Examples 35-53) 70 parts of the polyols a to s shown in Tables 8 to 10, 30 parts of the polyol y, 4.0 parts of the crosslinking agent ss, 1.0 part of the foam stabilizer v, a foaming agent A mixture of 2.7 parts of x, 0.60 part of amine catalyst t and 0.10 part of amine catalyst u was used as a polyol liquid, and polyisocyanate z was used as the polyisocyanate liquid. As well as. The isocyanate index was 100. Tables 8 to 10 show the foam physical properties, vibration characteristics, and moldability of the obtained foams.

The production method of the present invention is effective for producing a highly elastic polyurethane foam having improved ride performance and moldability.

Claims (7)

  In producing a highly elastic polyurethane foam by reacting a high molecular weight active hydrogen compound having two or more active hydrogen-containing functional groups capable of reacting with an isocyanate group and a polyisocyanate compound in the presence of a catalyst and a blowing agent, a high molecular weight active hydrogen is produced. A compound comprising a polyoxyalkylene polyol (A) obtained by ring-opening polymerization of a cyclic ether using a sodium or potassium catalyst in the presence of an initiator, and a composite metal cyanide complex catalyst or a cesium catalyst in the presence of an initiator. The polyoxyalkylene polyol (B) obtained by ring-opening polymerization of cyclic ether using (A) / (B) (weight ratio) is a mixed polyol obtained by mixing at 5/95 to 90/10. A method for producing a highly elastic polyurethane foam, which is characterized.   The production method according to claim 1, wherein the polyol (A) is a polyol containing 2 to 6 hydroxyl groups, a hydroxyl value of 20 to 60, and 3 to 25% by weight of an oxyethylene group at a terminal portion.   The production method according to claim 1 or 2, wherein the polyol (B) is a polyol having 2 to 6 hydroxyl groups, a hydroxyl value of 5 to 35, and 3 to 25% by weight of an oxyethylene group at a terminal portion.   The manufacturing method in any one of Claims 1-3 whose total unsaturation of a mixed polyol is 0.08 meq / g or less.   The manufacturing method in any one of Claims 1-4 whose total unsaturation degree of a polyol (B) is 0.05 meq / g or less.   The production method according to any one of claims 1 to 5, wherein the mixed polyol is a polymer-dispersed polyol containing fine polymer particles. The production method according to claim 1, wherein the foaming agent is at least one foaming agent selected from water and an inert gas.