JP5151461B2 - Method for producing flexible polyurethane foam and use thereof - Google Patents

Description

The present invention relates to a method for producing a flexible polyurethane foam using a high molecular weight polyol having a low hydroxyl value, a method for producing a flexible polyurethane foam obtained thereby, and its use .

  Conventionally, a flexible polyurethane foam is produced from a polyol as a raw material by an open production method such as a slab molding method or a closed production method using a sealed mold. As the slab foam produced by an open production method, a raw material polyol having a molecular weight of about 3000 to 5000 is generally used.

  In general, polyols used as raw materials for flexible polyurethane foams use sodium-based catalysts such as sodium hydroxide or potassium-based catalysts such as potassium hydroxide, and polyalkyl alcohols as initiators and alkylene oxides such as propylene oxide. It is produced by ring-opening addition polymerization. In this production method, a monool having an unsaturated bond (unsaturated monool) is produced as a by-product, and the amount of the unsaturated monool produced increases with a decrease in the hydroxyl value of the polyol (an increase in molecular weight).

  When a flexible polyurethane foam is produced using a polyol having a high degree of unsaturation, problems such as a decrease in hardness, a deterioration in compression set, and a decrease in curing property during molding occur. In addition, when trying to produce a polyol having a low hydroxyl value using a sodium-based catalyst or a potassium-based catalyst, the degree of unsaturation becomes remarkably high and the production becomes very difficult.

  On the other hand, as a method for producing a polyol having a low hydroxyl value and a low degree of unsaturation, a method of ring-opening addition polymerization of alkylene oxide using a double metal cyanide complex catalyst is known.

  Although it is possible to produce a polyol with a low degree of unsaturation if it is produced using a composite metal cyanide complex catalyst, the stability during foam production is reduced when a high molecular weight polyol having a hydroxyl value of 15 mgKOH / g or less is used as a raw material. However, it has been estimated that the production of flexible polyurethane foam is difficult.

  In order to improve the moldability problem, a flexible polyurethane foam using a polyol mixture of a polyol manufactured using a double metal cyanide complex catalyst and a polyol manufactured using a sodium hydroxide catalyst or a potassium hydroxide catalyst. Has been proposed (see Patent Document 1). However, the proposal relates to a mold foam and does not describe a production example using a high molecular weight polyol. Here, in the present invention, “moldability” means foam stability when a flexible polyurethane foam is produced. That is, good moldability means that no collapse or shrinkage occurs when a flexible polyurethane foam is produced.

In addition, a method for producing a slab foam using a polyol having a hydroxyl value of 10 to 80 mgKOH / g produced using a double metal cyanide complex catalyst has also been proposed (see Patent Documents 2 and 3). However, in the examples of these documents, only an example of producing a flexible foam with a polyol having a molecular weight of 5000 is described, and no production example using a higher polymer polyol is described.
In addition, a method for producing a flexible polyurethane foam having excellent mechanical properties such as tensile strength and elongation, using polyoxyalkylene diol having an average molecular weight of 1500 or more and polyoxyalkylene diol having an average molecular weight of 150 to 350 as essential components has also been proposed. (See Patent Document 4). The proposal describes an example in which the mechanical properties are insufficient when the two components are not essential, particularly when a polyoxyalkylene diol having two functional groups is not used. In addition, the proposal does not describe any example of producing a flexible polyurethane foam using a polyol having a molecular weight of 5000 or more as a raw material.
JP-A-8-231676 US Pat. No. 6,028,230 US Pat. No. 6,066,683 JP-A-2-286707

The present invention proposes a method for producing a flexible polyurethane foam using a high molecular weight polyol having a low hydroxyl value as a raw material, which has been conventionally difficult to produce. In the present invention, a flexible polyurethane foam having excellent mechanical properties can be produced by using a high molecular weight polyol .

  The present invention relates to a method for producing a flexible foam having good moldability using a high molecular weight polyol having a low hydroxyl value as a raw material. By using a high molecular weight polyol as a raw material, the obtained flexible polyurethane foam has a characteristic that mechanical properties are good. In addition, the flexible polyurethane foam obtained by the present invention has a feature that there is little change in physical properties due to temperature. Furthermore, by using a double metal cyanide complex catalyst, a polyol having a low degree of unsaturation and a narrow molecular weight distribution can be produced. Polyols with a narrow molecular weight distribution have a lower viscosity than polyols with a wide distribution, thus improving foam stability when producing flexible polyurethane foam

That is, the present invention relates to a process for producing a flexible polyurethane foam in an open state by reacting a polyol, a polyisocyanate compound, and a crosslinking agent in the presence of a catalyst, a foaming agent and a foam stabilizer, and propylene oxide is opened as an initiator to the initiator. A polyol having a number of hydroxyl groups of 2 to 8 and a hydroxyl value of 5 mgKOH / g or more and less than 10 mgKOH / g obtained by ring polymerization and ring-opening polymerization of ethylene oxide at the terminal is used, and the molecular weight is 4000 to 10,000 as a crosslinking agent. The present invention provides a method for producing a flexible polyurethane foam, characterized by using a crosslinking agent which is:

According to the flexible foam manufacturing method of the present invention, a flexible polyurethane foam having excellent mechanical properties can be manufactured. The flexible polyurethane foam obtained depending on the present invention is characterized in that the change in physical properties due to temperature is small.

The present invention relates to a method for producing a flexible polyurethane foam in an open system at room temperature by reacting a polyol, a polyisocyanate compound, and a crosslinking agent having a molecular weight of 4000 to 10,000 in the presence of a catalyst, a foaming agent and a foam stabilizer. And a polyol having a hydroxyl number of 2 to 8 and a hydroxyl value of 5 mgKOH / g or more and less than 10 mgKOH / g is used. That is, the present invention uses a high-molecular-weight polyol made from a high-molecular-weight polyol having a low hydroxyl value as a raw material, which has conventionally been difficult to produce foam, and a flexible polyurethane foam (hereinafter abbreviated as a flexible foam). It is characterized by manufacturing. A flexible foam produced using a high molecular weight polyol having a low hydroxyl value as a raw material is preferable because of its good mechanical properties. The flexible foam is preferred because it has low temperature sensitivity at low temperatures and can maintain foam properties under normal temperature conditions even under low temperature conditions.

The hydroxyl value of the polyol used in the present invention is less than 1 0 mgKOH / g.
The polyol having a low hydroxyl value used in the present invention can be obtained by subjecting an alkylene oxide to ring-opening addition polymerization reaction with an initiator using an appropriate polyol synthesis catalyst. Examples of the polyol synthesis catalyst include a double metal cyanide complex catalyst, a cesium hydroxide catalyst, and a phosphazenium compound catalyst. In order to produce a polyol having a low hydroxyl value, it is preferable to use a double metal cyanide complex catalyst.

  When this composite metal cyanide complex catalyst is used, a polyol having a low hydroxyl value and a narrow molecular weight distribution can be produced. A polyol having a narrow molecular weight distribution is preferable because it has a low viscosity as compared with a polyol having a broad molecular weight distribution in the same molecular weight region, so that the foam stability at the time of producing a flexible foam is improved.

As the composite metal cyanide complex catalyst, for example, those described in JP-B-46-27250 can be used. Specific examples include a complex mainly composed of zinc hexacyanocobaltate, and an ether and / or alcohol complex thereof is preferable.
Examples of the ether include ethylene glycol dimethyl ether (glyme), diethylene glycol dimethyl ether (diglyme), ethylene glycol mono-tert-butyl ether (METB), ethylene glycol mono-tert-pentyl ether (METP), and diethylene glycol mono-tert-butyl ether (DETB). , Tripropylene glycol monomethyl ether (TPME) and the like are preferable. Moreover, as said alcohol, tert- butyl alcohol etc. are preferable.

Examples of the alkylene oxide include ethylene oxide, propylene oxide, 1,2-epoxybutane, and 2,3-epoxybutane. In the present invention, ethylene oxide and propylene oxide are used in combination. In particular, it is preferable to use 50% by mass or more of propylene oxide as the alkylene oxide during the production of the polyol (the polyoxypropylene group in the polyoxyalkylene chain is 50% by mass or more).

  The initiator is preferably a compound having 2 to 6 active hydrogen atoms in the molecule, such as ethylene glycol, propylene glycol, 1,4-butanediol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, meso-erythritol. Polyhydric alcohols such as methyl glucoside, glucose and sorbitol; phenols such as bisphenol A; amines such as ethylenediamine, diethylenetriamine, piperazine, aminoethylpiperazine, diaminodiphenylmethane, monoethanolamine; condensation of phenol resin, novolac resin, etc. System compounds. Among the initiators, polyhydric alcohols are preferable. Two or more of these initiators may be used in combination, or may be used in combination with an active hydrogen compound such as sucrose having 7 or more active hydrogens. A compound obtained by further ring-opening addition of alkylene oxide to the above compound may be used as the initiator.

Polyols for use in the invention, you containing oxyethylene groups in the molecule. As a method for introducing an oxyethylene group into a polyol, for example, it can be obtained by addition polymerization of ethylene oxide and an alkylene oxide having 3 or more carbon atoms sequentially or mixed in an initiator. In particular, in the present invention, a polyol having an oxyethylene group at the molecular end, which is obtained by addition polymerization of ethylene oxide after the polymerization of propylene oxide, is used.

Number of hydroxyl groups of the polyol is 2-8, 2-6 are good preferred, particularly preferably 2.8 to 5.2. However, the number of hydroxyl groups means the average value of the number of active hydrogens in the initiator. By setting the number of hydroxyl groups to 2 or more, it is possible to avoid the disadvantage that the flexible foam becomes soft and the compression set deteriorates. By setting the number of hydroxyl groups to 8 or less, it is possible to avoid the disadvantage that the resulting flexible foam becomes hard and mechanical properties such as elongation are deteriorated.

The hydroxyl value of the polyol is less than 10 mgKOH / g . By using a polyol having a hydroxyl value of less than 10 mg KOH / g, it is possible to produce a flexible foam having excellent mechanical properties and small changes in physical properties due to temperature. On the other hand, if the hydroxyl value is too low, the viscosity of the polyol becomes high, which makes it substantially difficult to produce a flexible foam. That is, the hydroxyl value of the polyol is 5 mgKOH / g or more.

  The degree of unsaturation of the polyol used in the present invention is preferably 0.05 meq / g or less. By setting the degree of unsaturation to 0.05 meq / g or less, it is possible to avoid the disadvantage that the durability of the produced flexible foam deteriorates. More preferably, the degree of unsaturation of the polyol is 0.04 meq / g or less.

  The polyol used in the present invention may contain fine polymer particles. A dispersion system in which polymer fine particles are stably dispersed in a base polyol is referred to as a polymer-dispersed polyol. As the polymer fine particles, addition polymerization type polymer or condensation polymerization type polymer fine particles can be used. The addition polymerization polymer is obtained, for example, by polymerizing monomers such as acrylonitrile, styrene, methacrylic acid ester, acrylic acid ester alone or copolymerizing two or more kinds. Examples of the polycondensation polymer include polyester, polyurea, polyurethane, and melamine. By allowing the polymer fine particles to be present in the polyol, the hydroxyl value of the polyol can be kept low, which is effective in improving physical properties such as hardness and air permeability of the flexible foam. The content of the polymer fine particles in the polymer-dispersed polyol is not particularly limited, but is preferably 50% by mass or less, and more preferably 3 to 35% by mass. The various properties (unsaturation, hydroxyl value, etc.) of the polymer-dispersed polyol as a polyol are considered for the base polyol excluding the polymer fine particles.

  The flexible foam of the present invention is produced by reacting the aforementioned polyol and polyisocyanate compound in the presence of a urethanization reaction catalyst, a foaming agent and a foam stabilizer.

  The polyisocyanate compound used in the present invention is not particularly limited, and is a polyisocyanate having two or more isocyanate groups, such as aromatic, alicyclic, and aliphatic groups; a mixture of two or more of the above polyisocyanates; And modified polyisocyanates obtained by modifying. Specific examples include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI or monomeric MDI), polymethylene polyphenyl polyisocyanate (common name: crude MDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hexamethylene. Examples thereof include polyisocyanates such as diisocyanate (HMDI), or prepolymer-modified products thereof, nurate-modified products, urea-modified products, and carbodiimide-modified products. Among these, TDI, MDI, crude MDI, or modified products thereof are preferable. Further, among these, crude MDI or a modified product thereof (particularly a prepolymer modified product is preferred) is preferable in terms of improving foaming stability and improving durability.

  The use amount of the polyisocyanate compound is usually represented by an isocyanate index (a numerical value represented by 100 times the number of isocyanate groups with respect to the total number of all active hydrogens such as polyol, cross-linking agent, and water). The use amount of is preferably in the range of 40 to 120, more preferably in the range of 50 to 110 in terms of isocyanate index.

  As the urethanization catalyst for reacting the polyol and the polyisocyanate compound, any catalyst that promotes the urethanization reaction can be used, for example, triethylenediamine, bis (2-dimethylaminoethyl) ether, N, N, N ′. , N′-tetramethylhexamethylenediamine and the like; carboxylic acid metal salts such as potassium acetate and potassium 2-ethylhexanoate; organometallic compounds such as stannous octoate and dibutyltin dilaurate.

  The foaming agent is not particularly limited, but at least one selected from water and inert gas is preferable. Specific examples of the inert gas include air, nitrogen, carbon dioxide gas, and the like. Of these, water is preferred. Although the usage-amount of a foaming agent is not specifically limited, When using water, 10 mass parts or less are preferable with respect to 100 mass parts of polyols, and 0.1-8 mass parts is more preferable.

  As the foam stabilizer used in the present invention, those used in the production of ordinary polyurethane foams can be used, and examples thereof include silicone foam stabilizers, fluorine foam stabilizers, etc. Among these, silicone foam stabilizers. Agents are preferred. Here, the silicone-based foam stabilizer is a compound having a polysiloxane chain and a polyoxyalkylene chain. The polysiloxane chain means an organopolysiloxane chain having an organic group in the side chain, and examples thereof include a dimethylsiloxane chain. The polyoxyalkylene chain means a portion to which the same alkylene oxide as described above is added. Examples of the addition of alkylene oxide include block addition in which a single alkylene oxide is added, random addition in which two or more alkylene oxides are randomly added, and these additions may be mixed. The structure of the foam stabilizer may be a block type structure of a polysiloxane chain and a polyoxyalkylene chain, or a structure in which a polyoxyalkylene chain is grafted as a side chain to the main polysiloxane chain. . From the viewpoint of good moldability of the flexible foam, a structure in which a polyoxyalkylene chain is grafted as a side chain to the main polysiloxane chain is preferable.

  The foam stabilizer used in the present invention is most preferably a silicone foam stabilizer defined below. 10-50 mass% is preferable and, as for the silicone content of this foam stabilizer, 30-50 mass% is more preferable. Here, the silicone content is the ratio of the polysiloxane chain in the foam stabilizer, and the remainder is the polyoxyalkylene chain. Moreover, as content of ethylene oxide of this foam stabilizer, 70-100 mass% is preferable, and, as for content of the oxyethylene group in the said polyoxyalkylene chain, 90-100 mass% is more preferable. The chain length (corresponding to the molecular weight) of the polyoxyalkylene chain is preferably 1000 or less, and more preferably 500 or less.

  The polyoxyalkylene chain preferably has a hydroxyl group at the terminal. However, all the terminals need not be hydroxyl groups, and those having hydrogen atoms of the hydroxyl groups substituted with monovalent organic groups may be included. The proportion of hydroxyl groups in the terminals is preferably 50 to 100 mol%, more preferably 70 to 100 mol%, more preferably 100 mol%, i.e., all of the ends. A hydroxyl group is particularly preferred. Examples of the monovalent organic group include an alkyl group such as a methyl group, an ethyl group, and an isopropyl group; an aryl group such as a phenyl group; an acyl group such as an acetyl group; Organic groups are preferred.

  In the method for producing a flexible foam according to the present invention, two or more kinds of the foam stabilizers may be used in combination, or a foam stabilizer other than the specific foam stabilizer may be used in combination. In the production of the flexible foam according to the present invention, the amount of the foam stabilizer used is preferably 0.01 to 5 parts by mass, and 0.1 to 2 parts by mass with respect to 100 parts by mass of the polyol (but not including the crosslinking agent). Part is more preferred.

In the present invention, a crosslinking agent is also used.
As the crosslinking agent, a compound having two or more functional groups having active hydrogen such as a hydroxyl group, a primary amino group or a secondary amino group is preferable. The molecular weight of the crosslinking agent is 4000 to 10,000. Further, two or more crosslinking agents may be used in combination. Specific examples include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, pentaerythritol, diglycerin. , Dextrose, sorbitol, sucrose, monoethanolamine, diethanolamine, triethanolamine, bisphenol A, ethylenediamine, 3,5-diethyl-2,4 (or 2,6) -diaminotoluene (DETDA), 2-chloro-p -Phenylenediamine (CPA), 3,5-bis (methylthio) -2,4 (or 2,6) -diaminotoluene, 1-trifluoromethyl-4-chloro-3,5-diaminoben 2,4-toluenediamine, 2,6-toluenediamine, bis (3,5-dimethyl-4-aminophenyl) methane, 4,4′-diaminodiphenylmethane, m-xylylenediamine, 1,4-diamino Examples thereof include compounds such as hexane, 1,3-bis (aminomethyl) cyclohexane and isophoronediamine, and compounds obtained by adding alkylene oxide to these compounds.

  When the above crosslinking agent is used, for example, when a low-density flexible foam is produced using a large amount of a foaming agent, the foaming stability is improved and the flexible foam can be produced. In particular, when a high molecular weight polyol is used, it is possible to produce a low density flexible foam which has been difficult to foam. Moreover, durability is improved compared with the case where it does not use when a crosslinking agent is used. When a high molecular weight polyol is used as in the present invention, the foaming stability is particularly easily improved when a compound having a relatively high molecular weight, for example, a molecular weight of 4000 or more is used.

  In the method for producing a flexible foam of the present invention, a desired additive can be used in addition to the above-described catalyst, foaming agent, foam stabilizer, and crosslinking agent. Additives include fillers such as potassium carbonate and barium sulfate; surfactants such as emulsifiers and foam stabilizers; anti-aging agents such as antioxidants and ultraviolet absorbers; flame retardants, plasticizers, colorants, Examples include mold agents, foam breakers, dispersants, discoloration inhibitors and the like.

The flexible foam of the present invention can be molded into a predetermined shape by a slab molding method.
The production of polyurethane can be carried out by a usual method, and can be carried out by a known method such as a one-shot method, a semi-prepolymer method or a prepolymer method. For polyurethane production, a commonly used production apparatus can be used.

  The flexible foam according to the present invention is used for bedding, mats, cushions, seats and the like.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these. In addition, the numerical value of the foaming prescription column in the following Examples 1-16 represents a mass part. Examples 1 , 7 , and 9 are Examples, Examples 2 to 6 , 8 , and 10 are Reference Examples, and Examples 11 to 16 are Comparative Examples.

  The polyol used in the following Examples 1 to 16 was produced by the following method. The degree of unsaturation was measured by a method based on JIS K-1557. The DMC-glyme complex catalyst used in the production of polyol A described later indicates a zinc hexacyanocobaltate-ethylene glycol dimethyl ether complex catalyst, and the KOH catalyst used in the production of polyols C and D indicates a potassium hydroxide catalyst. Initiator 1 is a compound having a hydroxyl value of 56 mgKOH / g obtained by adding propylene oxide to glycerin, and initiator 2 is a compound having a hydroxyl value of 168 mgKOH / g obtained by adding propylene oxide to glycerin.

Production of polyol A In the presence of 3000 g of initiator 1, 21700 g of propylene oxide was reacted at about 120 ° C. using a DMC-glyme complex catalyst, and then 1300 g of ethylene oxide was reacted at about 120 ° C. using a KOH catalyst to complete the polymerization. did. After the reaction, an adsorbent (synthetic magnesium silicate) treatment and filtration were performed to obtain a polyoxyalkylene polyol A having a hydroxyl value of 9.14 mgKOH / g and an unsaturation degree of 0.038 meq / g.

Production of Polyol C In the presence of 1000 g of initiator 2, 4250 g of propylene oxide was reacted at about 110 ° C. using a KOH catalyst, and then 800 g of ethylene oxide was reacted at about 120 ° C. to complete the polymerization. After the reaction, an adsorbent (synthetic magnesium silicate) treatment and filtration were performed to obtain a polyoxyalkylene polyol C having a hydroxyl value of 34.0 mgKOH / g and an unsaturation degree of 0.056 meq / g.

Production of Polyol D In the presence of 1000 g of initiator 2, 2200 g of a mixture of ethylene oxide and propylene oxide containing 10% by mass of ethylene oxide was reacted at about 110 ° C. using a KOH catalyst to complete the production. After the reaction, an adsorbent (synthetic magnesium silicate) treatment and filtration were performed to obtain polyol D having a hydroxyl value of 56.1 mgKOH / g and an unsaturation degree of 0.045 meq / g.

The flexible foam was manufactured using the raw material and compounding quantity (a number shows a mass part) shown in Table 1-4. In Examples 1 to 10, among these raw materials and compounding agents, the liquid temperature of the mixture of all raw materials other than polyisocyanate was adjusted to 50 ° C. ± 1 ° C., and the polyisocyanate compound solution was adjusted to liquid temperature 20 ± 1 ° C. A predetermined amount of a polyisocyanate compound was added to the polyol-containing mixture, and a total amount of 1 kg was mixed with a high-speed mixer for 5 seconds, and poured into a wooden box having a vertical and horizontal length and a height of 300 mm each having an open top at room temperature. The polyurethane foam was taken out and allowed to stand for 24 hours or longer, and various physical properties were measured.
In Examples 11 to 16, polyurethane foams were produced in the same manner as in Examples 1 to 10 except that the mixture of all raw materials other than polyisocyanate and the polyisocyanate compound solution were adjusted to 25 ° C. ± 1 ° C., respectively.

  The measurement results are shown in Tables 2 to 4. In addition, the measurement method of foam physical property was based on the following, and regarding the density, what was cut out to the size of 100 mm each length and width 50mm except the edge part from the center part of the foam was used for the measurement. In Tables 2 to 4, the degree of unsaturation is the total degree of unsaturation of the base polyol in the polyol and polymer-dispersed polyol, and the unit is (meq / g).

The standards used for measuring the physical properties of the flexible foam are shown below.
Core density (unit: kg / m ³ ), 25% hardness (ILD) (unit: N / 314 cm ² ), CLD hardness (unit: N / cm ² ), core rebound resilience (unit:%), tear strength (Unit: N / cm), tensile strength (unit: kPa), elongation (unit:%), dry heat compression set (unit:%), air permeability (unit: ft ³ / min (SI conversion: 28. 3L / min)) is a method based on JIS K-6400. The stability (settling rate) of the foam is calculated based on the following formula, and the settling rate is 0% to less than 20%: good ○, 20% to less than 40%: almost good Δ, 40% or more: × As evaluated. Settling rate = ((maximum foaming height−final foaming height) / maximum foaming height) × 100 As for closed cell properties (crushing properties), there is no shrinkage after foaming: ○, there is shrinkage after foaming Returned to the original after crushing: Δ, shrinkage after foaming, not returned after crushing several times: evaluated as ×.

Synthesis of polyisocyanate d3 In a 1 L three-necked flask, 1000 g of crude MDI (trade name: Millionate MR200, manufactured by Nippon Polyurethane Industry Co., Ltd., isocyanate group content 31.0%) was charged in a nitrogen atmosphere, and then polyethylene glycol monomethyl ether ( (Product name: MPG-081, manufactured by Nippon Emulsifier Co., Ltd., hydroxyl value 84.0 mgKOH / g) 36.1 g was continuously added dropwise with stirring, and reacted at 70 ° C. for 3 hours to obtain an isocyanate group-terminated prepolymer. . The isocyanate group content of this prepolymer was 29.5% by mass.

From the results shown in Tables 2 to 4, the flexible foams of Examples 1 to 10 produced using a polyol having a hydroxyl value of 15 mgKOH / g or less were obtained from Examples 11 to 11 produced using a polyol having a higher hydroxyl value. It was found to have superior mechanical properties compared to 16 flexible foams. The average hydroxyl value of the polyol mixture of Example 6 is 12.0 mgKOH / g.
In Examples and Comparative Examples, the case where isocyanate used TDI (Examples 1-6, 11, 12) and the case where MDI (including prepolymerization) was used (Examples 7-10, 13-16) It can be divided and divided. In other words, when MDI is used, the dry heat compression set (which is preferably smaller), which is an index of durability, is less than 7% in the example and is a preferable value compared to the comparative example. As mechanical properties, three points of tear strength, tensile strength, and elongation (which are preferably larger) can be compared, but these values are equal to or greater than those of the comparative examples in the examples. On the other hand, when TDI is used, the dry heat compression set is less than 7%, which is a preferable value compared to the comparative example. In addition, with respect to mechanical properties, particularly in terms of tensile strength and elongation, the examples have values superior to the comparative examples.
In particular, by using a prepolymerized MDI, the foam stability is good even when a low hydroxyl number polyol, which has been conventionally difficult to produce, is used (particularly stable in the examples). It was found that a flexible foam having excellent durability was obtained.
The flexible foams of Examples 1 to 10 have little change in physical properties (−25 ° C./23° C. hardness ratio) due to temperature change (ideally, there is no change, and the ratio is preferably 1). It has characteristics.

Claims (7)

In the method of producing a flexible polyurethane foam in an open state by reacting a polyol, a polyisocyanate compound and a crosslinking agent in the presence of a catalyst, a foaming agent and a foam stabilizer, propylene oxide is ring-opening polymerized as an polyol to the initiator, and A polyol having a hydroxyl number of 2 to 8, a hydroxyl value of 5 mgKOH / g or more and less than 10 mgKOH / g obtained by ring-opening polymerization of ethylene oxide at the terminal is used, and a polyol having a molecular weight of 4000 to 10,000 is used as a crosslinking agent. A method for producing a flexible polyurethane foam, comprising:   The method for producing a flexible polyurethane foam according to claim 1, wherein the polyol does not contain a polymer-dispersed polyol. The method for producing a flexible polyurethane foam according to claim 1 or 2, wherein a silicone-based foam stabilizer having a silicone content of 30 to 50% by mass is used as the foam stabilizer.   The bedding using the flexible polyurethane foam obtained by the method as described in any one of Claims 1-3.   The mat using the flexible polyurethane foam obtained by the method as described in any one of Claims 1-3.   The cushion using the flexible polyurethane foam obtained by the method as described in any one of Claims 1-3.   The seat using the flexible polyurethane foam obtained by the method as described in any one of Claims 1-3.