JP2012102156A - Method of manufacturing flexible polyurethane foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing flexible polyurethane foam which excels in foam stability under foaming, has low density, and excels in machine physical properties also in a formulation in which an amount of water is made to increase as a foaming agent.SOLUTION: The method of manufacturing flexible polyurethane foam makes a polyol and isocyanate react under the presence of a catalyst and a foaming agent, wherein as a part of the polyol, a diol shown by formula (1), and in which a hydroxy group value is in a range of 100-1,500 mgKOH/g is used, and water is used as a foaming agent. In the formula (1), A denotes a bivalent substituent which has at least one cyclohexylene group or phenylene group in a main chain, R denotes a hydrogen atom or a 1-4C alkyl group, m denotes an integer of 0-2, and n denotes an integer of 0-3.

Description

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

  Polyurethane foams are widely used as rigid foams used in vehicle seat cushions, mattresses, furniture and other soft foams, vehicle instrument panels, semi-rigid foams such as headrests and armrests, electric refrigerators and building materials.

  In recent years, in order to reduce the weight of a vehicle body and improve the fuel consumption rate, there has been a strong demand for lowering the density of a flexible polyurethane foam for vehicles (hereinafter sometimes simply referred to as “foam”).

  With regard to the blowing agent used for reducing the density of the foam, halogenated hydrocarbons having a high ozone depletion coefficient or global warming potential [for example, chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydro Reduction or removal of fluorocarbons (HFCs) is being studied (for example, see Patent Document 1).

  At present, instead of reducing or eliminating these halogenated hydrocarbons that have been used as blowing agents, the amount of water as blowing agent is increased, and the foam is formed by carbon dioxide produced by the reaction of isocyanate and water. Lowering the density has become mainstream (see, for example, Patent Document 2).

  However, when the amount of water as a foaming agent is increased, foam stability is lost during foaming and the foam collapses. As a result, there is a problem that the density of the foam cannot be sufficiently reduced.

  For this reason, a method using a chain extender or a cross-linking agent is widely used to achieve a sufficiently low foam density in a foam production formulation using water as a foaming agent. For example, a crosslinking agent such as diethanolamine or triethanolamine has a high effect of increasing foam stability and obtaining a low-density foam in a formulation with an increased amount of water as a foaming agent. Widely used in manufacturing (see, for example, Patent Document 3 and Patent Document 4).

  However, when the above-described chain extender or cross-linking agent is used, the foam density can be reduced, but the mechanical properties such as the tear strength of the foam are lowered. There were problems such as tearing and detracting from the value as a product. Therefore, there is a strong demand for development of a prescription technology for a flexible polyurethane foam having low density and excellent mechanical properties while using water as a main foaming agent.

JP-A-5-51478 Japanese Patent Laid-Open No. 1-259022 JP-A-63-75021 JP 2002-338654 A

  The present invention has been made in view of the above-mentioned background art, and the purpose thereof is a soft foam having excellent foam stability during foaming, low density and excellent mechanical properties even in a formulation in which the amount of water is increased as a foaming agent. It is to provide a method for producing a polyurethane foam.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have surprisingly found that when a specific diol compound having an aromatic ring or a cyclohexyl ring in the molecule is used as part or all of the polyol, In a formulation with extremely high foam foaming stability and increased water content as a foaming agent, it is possible to achieve a sufficiently low density of the flexible polyurethane foam and flexible polyurethane with excellent foam mechanical properties such as tear strength It has been found that it has an excellent effect that a foam can be obtained, and the present invention has been completed.

  That is, this invention is a manufacturing method of the flexible polyurethane foam as shown below.

  [1] A process for producing a flexible polyurethane foam in which a polyol and an isocyanate are reacted in the presence of a catalyst and a foaming agent, and is represented by the following formula (1) as a part of the polyol and has a hydroxyl group value of 100 to 1500 mgKOH A process for producing a flexible polyurethane foam, characterized in that a diol in the range of / g is used and water is used as a blowing agent.

［上記式（１）中、Ａは、下式（２）〜（５）のいずれかで示される二価の置換基を表し、Ｒは水素原子又は炭素数１〜４のアルキル基を表し、ｍは０〜２の整数、ｍは０〜３の整数を表す。

[In said formula (1), A represents the bivalent substituent shown by either of the following formula (2)-(5), R represents a hydrogen atom or a C1-C4 alkyl group, m represents an integer of 0 to 2, and m represents an integer of 0 to 3.

（上記式（３）中、Ｒ^１、Ｒ^２は各々独立して水素原子又は炭素数１〜４のアルキル基を表す。）

(In said formula (3), R < ¹ >, R < ² > represents a hydrogen atom or a C1-C4 alkyl group each independently.)

（上記式（５）中、Ｒ_１、Ｒ_２は各々独立して水素原子又は炭素数１〜４のアルキル基を表す。）］
［２］上記式（１）で示されるジオールが、第一級ヒドロキシル基末端を有することを特徴とする上記［１］に記載の軟質ポリウレタンフォームの製造法。

(In the above formula (5), R ₁ and R ₂ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)]
[2] The method for producing a flexible polyurethane foam according to [1], wherein the diol represented by the formula (1) has a primary hydroxyl group terminal.

  [3] The diol represented by the formula (1) is selected from the group consisting of cyclohexanediol, cyclohexanedimethanol, hydroquinone bis (2-hydroxyethyl) ether, dihydroxydiphenylmethane, bisphenol A hydride, and bisphenol A ethoxylate. The method for producing a flexible polyurethane foam according to the above [1] or [2], which is at least one kind.

  [4] The amount of the diol represented by the above formula (1) is polyol [including the diol represented by the above formula (1). ] The method for producing a flexible polyurethane foam according to any one of the above [1] to [3], which is in the range of 0.01 to 20 parts by weight with respect to 100 parts by weight.

  [5] The amount of water used includes a polyol [a diol represented by the formula (1). ] The method for producing a flexible polyurethane foam according to any one of the above [1] to [4], which is in the range of 1 to 30 parts by weight with respect to 100 parts by weight.

  [6] The method for producing a flexible polyurethane foam according to any one of the above [1] to [5], wherein the isocyanate is an aromatic isocyanate.

  [7] The method for producing a flexible polyurethane foam according to any one of the above [1] to [6], wherein the isocyanate index is in the range of 50 to 150.

  According to the present invention, it is possible to produce a low-density flexible polyurethane foam by improving the stability during foaming in the formulation of a flexible polyurethane foam having an increased amount of water as a foaming agent. Compared with the case of using an extender and a crosslinking agent, it is possible to improve the mechanical properties of the foam such as tear strength.

  Next, the present invention will be described in detail.

  The method for producing a flexible polyurethane foam of the present invention is a method for producing a flexible polyurethane foam in which a polyol and an isocyanate are reacted in the presence of a catalyst and a foaming agent, and is represented by the above formula (1) as a part of the polyol. It is characterized by using a diol having a hydroxyl group value in the range of 100 to 1500 mg KOH / g and using water as a blowing agent.

Here, the flexible polyurethane foam is a reversibly deformable foam having an open cell structure and exhibiting high air permeability [eg Gunter Oertel, “Polyurethane Handbook” (1985 edition), Hanser Publisher (Germany), No. 161-233, Keiji Iwata, “Polyurethane Resin Handbook” (1987 First Edition), Nikkan Kogyo Shimbun, pages 150-221]. The physical properties of flexible polyurethane foam vary depending on the chemical structure such as polyol and isocyanate used in its production, the blending amount of the blowing agent, the chemical factor such as isocyanate index, the cell structure, etc. In general, the density is 10 to 100 kg / m ³ (JIS K 6401), the compressive strength (ILD 25%) is 2 to 80 kgf (20 to 800 N) (JIS K 6401), and the elongation is 80 to 500%. [JIS K 6301] [for example, Gunter Oertel, “Polyurethane Handbook” (1985 edition), Hanser Publisher (Germany), pages 184 to 191 and pages 212 to 218, Keiji Iwata “Polyurethane Resin Handbook” ( (First edition in 1987) Nikkan Kogyo Newspaper, pp 160-166 and the 186-191 Reference.

The semi-rigid polyurethane foam is a reversibly deformable foam having an open cell structure and high air permeability like the flexible polyurethane foam, although its foam density and compressive strength are higher than those of the flexible polyurethane foam. Since the raw materials such as polyol and isocyanate used for the production are the same as those of the flexible polyurethane foam, they are generally classified into the flexible polyurethane foam [for example, Gunter Oeltel, “Polyurethane Handbook” (1985 edition) Hanser. Publisher (Germany), pp. 223-233, Keiji Iwata “Polyurethane Resin Handbook” (first edition in 1987), Nikkan Kogyo Shimbun, pp. 211-221]. The physical properties of the semi-rigid polyurethane foam are not particularly limited. Generally, the density is 40 to 800 kg / m ³ , and the 25% compressive strength is 0.1 to ² kgf / cm ² (9.8 to 200 kPa). The elongation is in the range of 40 to 200%.

In contrast, rigid polyurethane foams have a highly crosslinked closed cell structure and are not reversibly deformable, and have completely different properties than flexible and semi-rigid polyurethane foams [eg Gunter Oeltel, “Polyurethane”. Handbook "(1985 edition) Hanser Publisher (Germany), pp. 234-313, Keiji Iwata" Polyurethane resin handbook "(1987 first edition) Nikkan Kogyo Shimbun, pp. 224-283]. The properties of the rigid foam are not particularly limited, but in general, the density is in the range of ²⁰ to 100 kg / m ³ and the compressive strength is in the range of 0.5 to 10 kgf / cm ² (50 to 1000 kPa).

  The flexible polyurethane foam in the present invention includes the above-mentioned semi-rigid polyurethane foam from the viewpoint of raw materials and foam properties used for the production.

  In the present invention, the divalent substituent A in the diol represented by the above formula (1) is not particularly limited, but examples of the divalent substituent represented by the above formula (2) include 1, Examples include 2-, 1,3-, or 1,4-cyclohexylene groups.

  In addition, as the divalent substituent represented by the above formula (3), two 1,2-, 1,3-, or 1,4-cyclohexylene groups are bonded to each other by a methylene chain or an isopropylidene chain. The substituent which is made is illustrated.

  Examples of the divalent substituent represented by the above formula (4) include 1,2-, 1,3-, or 1,4-phenylene groups.

  Further, as the divalent substituent represented by the above formula (5), two 1,2-, 1,3-, or 1,4-phenylene groups are bonded to each other by a methylene chain or an isopropylidene chain. Examples of the substituent are as follows.

  In the present invention, the substituent R in the diol represented by the above formula (1) is preferably a hydrogen atom or a methyl group.

  In the present invention, the diol represented by the above formula (1) specifically includes cyclohexanediol, cyclohexanedimethanol, hydroquinone bis (2-hydroxyethyl) ether, dihydroxydiphenylmethane, bisphenol A hydride, bisphenol A ethoxylate. Of these, 1,4-cyclohexanedimethanol, hydroquinone bis (2-hydroxyethyl) ether, and bisphenol A ethoxylate are preferred.

  In the present invention, the diol represented by the above formula (1) may be used alone or in combination of two or more.

  In the present invention, the diol represented by the above formula (1) is used as a part of a polyol used for producing a flexible polyurethane foam. The amount of the diol represented by the above formula (1) is not particularly limited, but polyol [including the diol represented by the above formula (1). ] The range is usually 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight per 100 parts by weight. When the usage-amount of diol shown by said Formula (1) is less than 0.01 weight part with respect to 100 weight part of polyols, there exists a possibility that effects, such as foam stability improvement, may not be acquired. On the other hand, when it is used in excess of 20 parts by weight, there is a risk that the foam may be extremely closed and cause shrinkage, and it is economically disadvantageous.

  In this invention, it is preferable to use together the diol shown by said Formula (1), and other polyols. In the present invention, examples of the polyol used in combination with the diol represented by the formula (1) include conventionally known polyester polyols, polyether polyols, polymer polyols, and mixtures thereof.

  Examples of conventionally known polyester polyols include compounds derived from dibasic acids and polyhydric alcohols. Examples of conventionally known polyether polyols include polyhydric alcohols such as glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sucrose, aliphatic amine compounds such as ammonia, ethylenediamine, and ethanolamine, and toluenediamine. , Diphenylmethane-4, 4′-diamine and the like, and / or compounds obtained by adding ethylene oxide, propylene oxide and the like to a mixture thereof. Examples of conventionally known polymer polyols include polymer polyols obtained by reacting polyether polyols and ethylenically unsaturated monomers (for example, butadiene, acrylonitrile, styrene, etc.) in the presence of a radical polymerization catalyst. .

  In the present invention, the above-described polyether polyol and / or polymer polyol is preferable as the polyol used in combination with the diol represented by the above formula (1). The average functionality is in the range of 2 to 5, the average hydroxyl value is in the range of 20 to 100 mgKOH / g, the oxyethylene group content is preferably 90% or less, and the average hydroxyl value is more preferably in the range of 20 to 80 mgKOH / g.

  In the present invention, if necessary, a conventionally known crosslinking agent or chain extender can be used. Examples of such a crosslinking agent or chain extender include low molecular weight polyhydric alcohols such as ethylene glycol, diethylene glycol, 1,4-butanediol, and glycerin, and low molecular weight amine polyols such as diethanolamine and triethanolamine. Or polyamines such as ethylenediamine, xylylenediamine, and methylenebisorthochloroaniline.

  In the present invention, examples of the isocyanate include conventionally known polyisocyanates, and specifically, tolylene diisocyanate (TDI), 4,4′- or 4,2′-diphenylmethane diisocyanate (MDI), naphthylene diene. Aromatic polyisocyanates such as isocyanate and xylylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and free isocyanate-containing prepolymers by reaction of these polyisocyanates and polyols And modified polyisocyanates such as carbodiimide-modified isocyanate, mixed polyisocyanates thereof and the like.

  Among these, TDI and its derivatives or MDI and its derivatives are preferable, and these may be used in combination. Examples of TDI and its derivatives include a mixture of 2,4-TDI and 2,6-TDI or a terminal isocyanate prepolymer derivative of TDI. Examples of MDI and its derivatives include a mixture of MDI and its polymer polyphenylpolymethylene diisocyanate, and diphenylmethane diisocyanate derivatives having terminal isocyanate groups.

  In the present invention, the isocyanate index [{(isocyanate group) / (isocyanate reactive group)} × in order to adjust the hardness, density, strength, and durability characteristics of the foam and meet various requirements for the mechanical properties of the foam. 100 (equivalent ratio)] can be adjusted. In the present invention, the isocyanate index is preferably in the range of 50 to 150, more preferably in the range of 60 to 140. If the isocyanate index is less than 50, the surface of the resulting polyurethane foam tends to be sticky. On the other hand, if it exceeds 150, the foam production time (curing time) becomes longer and the resulting foam is It tends to be hard.

  Examples of the tertiary amine catalyst used in the method of the present invention include triethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetramethylpropylenediamine, N , N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, N, N, N ′, N ″, N ″ -pentamethyl- (3-aminopropyl) ethylenediamine, N, N, N ′, N ″, N "-Pentamethyldipropylenetriamine, N, N, N ', N'-tetramethylguanidine, 1,3,5-tris (N, N-dimethylaminopropyl) hexahydro-S-triazine, 1,8-diazabicyclo [ 5.4.0] Undecene-7, N, N, N ′, N′-tetramethylhexamethylenediamine, N-methyl-N ′-(2-dimethylaminoethyl) pi Razine, N, N′-dimethylpiperazine, dimethylcyclohexylamine, N-methylmorpholine, N-ethylmorpholine, bis (2-dimethylaminoethyl) ether, N, N, N′-trimethyl-N′-hydroxyethylbis ( Aminoethyl) ether, N, N-dimethylaminoethanol, N, N-dimethylisopropanolamine, N, N-dimethylpropanolamine, N, N-dimethylpropanediamine, N, N-dimethylhexanolamine, N, N-dimethyl Aminoethoxyethanol, N, N, N′-trimethyl-N ′-(2-hydroxyethyl) ethylenediamine, N, N, N′-trimethyl-N ′-(2-hydroxyethyl) propanediamine, N-methyl-N '-(2-hydroxyethyl) piperazine, bis (N N-dimethylaminopropyl) amine, bis (N, N-dimethylaminopropyl) isopropanolamine, 2-aminoquinuclidine, 3-aminoquinuclidine, 4-aminoquinuclidine, 2-quinuclidinol, 3-quinuclidinol, 4-quinuclidinol, 2-hydroxymethyltriethylenediamine, N, N-dimethylaminopropyl-N ′-(2-hydroxyethyl) amine, N, N-dimethylaminopropyl-N ′, N′-bis (2-hydroxyethyl) ) Amine, N, N-dimethylaminopropyl-N ′, N′-bis (2-hydroxypropyl) amine, N, N-dimethylaminoethyl-N ′, N′-bis (2-hydroxyethyl) amine, and N, N-dimethylaminoethyl-N ′, N′-bis (2-hydroxypropyl) a Min, 1,2-dimethylimidazole, 1-methylimidazole, 1,4-dimethylimidazole, 1,2,4,5-tetramethylimidazole, 1-methyl-2-isopropylimidazole, 1-methyl-2-phenylimidazole 1- (n-butyl) -2-methylimidazole, 1-isobutyl-2-methylimidazole, 1-vinylimidazole, 1-benzyl-2-methylimidazole, imidazole, 2-methylimidazole, 1- (2′- Hydroxypropyl) -imidazole, 1- (2′-hydroxypropyl) -2-methylimidazole, 1- (2′-hydroxyethyl) -imidazole, 1- (2′-hydroxyethyl) -2-methylimidazole, 1- (3′-aminopropyl) -imidazole, 1- (3′-amino) (Lopyl) -2-methylimidazole, 1- (3′-dimethylaminopropyl) imidazole, 1- (3′-hydroxypropyl) -imidazole, 1- (3′-hydroxypropyl) -2-methylimidazole and the like can be exemplified. .

  Among these, triethylenediamine, 2-hydroxymethyltriethylenediamine, bis (2-dimethylaminoethyl) ether, N, N, N′-trimethyl-N′-hydroxyethylbis (aminoethyl) ether has high catalytic activity. Industrially advantageous in the method of the present invention.

  In the method of the present invention, a metal catalyst can be used in combination. Such a metal catalyst is not particularly limited as long as it is a conventionally known metal catalyst. Specifically, stannous diacetate, stannous dioctoate, stannous dioleate, stannous dilaurate, dibutyltin Conventionally known organotin compounds such as oxide, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, dioctyltin dilaurate and the like can be mentioned.

  These catalysts may be diluted with a solvent if necessary. The solvent is not particularly limited as long as it is usually used. For example, dipropylene glycol, ethylene glycol, 1,4-butanediol, diethylene glycol and water can be used.

  The amount of these catalysts used is usually 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, when the polyol is 100 parts by weight.

  In the present invention, the foaming agent is water, but if necessary, a conventionally known physical foaming agent or chemical foaming agent can be used in combination.

  Examples of conventionally known physical blowing agents include hydrocarbons such as pentane and cyclopentane, and gas mixtures such as air, nitrogen and carbon dioxide. Conventionally known chemical foaming agents include gases such as organic acids, boric acid and other inorganic acids, alkali carbonates, cyclic carbonates, dialkyl carbonates, etc. that react with polyurethane resin components or decompose by heat. To be made.

  In the present invention, the amount of water used is polyol [including the diol represented by the above formula (1) in order to reduce the density of the foam and improve the moldability. The range of 1 to 30 parts by weight is preferable with respect to 100 parts by weight, and the range of 2 to 20 parts by weight is more preferable.

  In the present invention, if necessary, a foam stabilizer can be used. The foam stabilizer may be a conventionally known foam stabilizer and is not particularly limited. For example, nonionic surfactants such as an organosiloxane-polyoxyalkylene copolymer and a silicone-grease copolymer, Or a mixture thereof or the like can be mentioned. Although the usage-amount is not specifically limited, A polyol [The diol shown by said Formula (1) is included. ] The range is usually 0.1 to 10 parts by weight per 100 parts by weight.

  In the present invention, if necessary, colorants, flame retardants, anti-aging agents, and other conventionally known additives may be used. The types of these additives and the amount thereof added are sufficient within the range usually used.

  Hereinafter, although demonstrated based on an Example and a comparative example, this invention is limited to only these Examples and is not interpreted.

  A flexible polyurethane foam was foamed using the formulation shown in Table 1 and various chain extenders or cross-linking agents shown in Table 2. The conditions for the foam test are shown below.

[Foaming conditions]
・ Raw material temperature: 20 ± 1 ℃
-Stirring speed: 6000 rpm (5 seconds).

  At room temperature, the reactivity and foam physical properties of a flexible polyurethane foam obtained by pouring and foaming a polyurethane raw material into a 2 liter polyethylene cup were measured by the following methods. The results are shown in Table 2.

[Reactivity]
Cream time: foaming start time (seconds). Time from the start of mixing raw materials until the raw material mixture becomes cloudy and rises up in a creamy state.

  Gel time: Resinization time (seconds). The time when the viscosity starts to increase and gel strength starts to appear after mixing the raw materials.

[Settling]
Settling refers to the rate at which foamed foam sinks after reaching its maximum height. The foam height during foaming was measured every second and settling was determined by the following equation.

Settling (%) = (A−B) / A × 100,
A: Maximum height of foam during foaming (mm),
B: Foam height (mm) 90 seconds after the start of foaming.

  Those with a small settling can be said to have high foam stability.

[Form density]
The weight of the test piece (dimension 70 × 70 × 50 mm) collected from the center of the foam was measured, and the value divided by the volume of the test piece was taken as the foam density.

[Tear strength]
After slicing the central part (70 × 70 × 50 mm) of the flexible polyurethane foam removed from the 2 liter polyethylene cup 10 minutes after the start of foaming to a thickness of 5 mm, using a No. 4 type dumbbell defined in JIS K6400 A test piece was prepared. 15 minutes after the start of foaming, using a tensile tester, pull the test piece at a constant speed, measure the maximum force shown until the test piece breaks, and divide the value by the thickness of the test piece. It was.

[Heat heat compression set]
A test piece (50 × 50 × 30 mm) is cut from the center of the foam, and the dimensions of the test piece are measured. The specimen is placed in an oven with 50% compression and aged at 70 ° C. for 22 hours. After 22 hours, the test piece is taken out, released from the compressed state, and allowed to stand at room temperature for 30 minutes. Then, the dimension of the test piece is measured, and the dimensional change rate before and after the test is calculated. The wet heat compression set is calculated by the following formula.

Humid heat compression set (%) = (A−B) / A × 100,
A: Thickness (mm) of test piece before aging,
B: Thickness (mm) of the test piece after aging.

表２から明らかなように、上記式（１）で示されるジオールを使用して、軟質ポリウレタンフォームを製造した実施例１〜実施例１４は、発泡中の安定性が改善され、低密度なフォームを製造することができた。更に、上記式（１）で示されるジオールを使用して得た軟質ポリウレタンフォームは、発泡後の引裂強度が０．５ｋｇｆ／ｃｍ以上と高かった。したがって、本発明によれば、実際のフォーム製造において、金型から取り出す際にフォームが裂ける等の問題が改善される。

As is clear from Table 2, Examples 1 to 14 in which flexible polyurethane foams were produced using the diol represented by the above formula (1) were improved in stability during foaming and low density foams. Could be manufactured. Furthermore, the flexible polyurethane foam obtained by using the diol represented by the above formula (1) had a high tear strength after foaming of 0.5 kgf / cm or more. Therefore, according to the present invention, in actual foam production, problems such as tearing of the foam when being taken out from the mold are improved.

  On the other hand, when a flexible polyurethane foam is produced using diethanolamine and triethanolamine, which are conventionally known crosslinking agents, the foam tear strength is 0.4 kgf / cm or less, although the stability during foaming is improved. Since it worsened, the defect rate increased and there was a problem in terms of productivity (see Comparative Examples 1 and 2).

Furthermore, when no chain extender and crosslinker were used, the foam stability during foaming deteriorated and the settling was larger than 10%. As a result, the foam density was 45 kg / m ³ or more, and a reduction in foam density was not achieved (see Comparative Example 3).

Claims (7)

A method for producing a flexible polyurethane foam in which a polyol and an isocyanate are reacted in the presence of a catalyst and a foaming agent, wherein the polyol is partly represented by the following formula (1) and has a hydroxyl group value of 100 to 1500 mgKOH / g. A method for producing a flexible polyurethane foam, comprising using a diol in a range and water as a foaming agent.

[In said formula (1), A represents the bivalent substituent shown by either of the following formula (2)-(5), R represents a hydrogen atom or a C1-C4 alkyl group, m represents an integer of 0 to 2, and m represents an integer of 0 to 3.

(In said formula (3), R < ¹ >, R < ² > represents a hydrogen atom or a C1-C4 alkyl group each independently.)

(In the above formula (5), R ₁ and R ₂ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)]   The process for producing a flexible polyurethane foam according to claim 1, wherein the diol represented by the formula (1) has at least one primary hydroxyl group end.   The diol represented by the formula (1) is at least one selected from the group consisting of cyclohexanediol, cyclohexanedimethanol, hydroquinone bis (2-hydroxyethyl) ether, dihydroxydiphenylmethane, bisphenol A hydride, and bisphenol A ethoxylate. The method for producing a flexible polyurethane foam according to claim 1 or 2, wherein the method comprises the steps of: The use amount of the diol represented by the formula (1) includes a polyol [the diol represented by the formula (1). The method for producing a flexible polyurethane foam according to any one of claims 1 to 3, wherein the content is in the range of 0.01 to 20 parts by weight per 100 parts by weight. The amount of water used is polyol [including the diol represented by the formula (1). The method for producing a flexible polyurethane foam according to any one of claims 1 to 4, wherein the amount is from 1 to 30 parts by weight per 100 parts by weight. The process for producing a flexible polyurethane foam according to any one of claims 1 to 5, wherein the isocyanate is an aromatic isocyanate. The method for producing a flexible polyurethane foam according to any one of claims 1 to 6, wherein the isocyanate index is in the range of 50 to 150.