JP2023091890A - Flexible polyurethane foam formable composition and flexible polyurethane foam - Google Patents

Abstract

To provide a flexible polyurethane foam formable composition contributing to making of a flexible polyurethane foam which has low density, adequate softness, strong mechanical properties and durability.SOLUTION: A flexible polyurethane foam formable composition is provided, including a polyol component (A), a catalyst (B), a foam stabilizer (C), a blowing agent (D), and a polyisocyanate component (E), wherein a ratio of a foaming reaction rate constant to a resinification reaction rate constant of the catalyst (B) is 0.090 or less, the polyisocyanate component (E) includes diphenylmethane diisocyanate (E-1) and polymethylene polyphenylene polyisocyanate (E-2) as an arbitrary component, and in the polyisocyanate component (E), a content of the diphenylmethane diisocyanate (E-1) is 75 mass% or more and 100 mass% or less, and a content of the polymethylene polyphenylene polyisocyanate (E-2) is 0 mass% or more and 25 mass% or less.SELECTED DRAWING: None

Description

The present disclosure relates to flexible polyurethane foam-forming compositions and flexible polyurethane foams.

Flexible polyurethane foams have excellent cushioning properties, and are therefore widely used for cushion members of furniture and the like, as well as automobile seats. These flexible polyurethane foams are required to have various properties such as foam physical properties, moldability and surface curability.

Here, in Patent Document 1, pure MDI (a) is subjected to a urethanization reaction with polyol (b) in an equivalent amount or less, and then polymeric MDI (c) is mixed, resulting in (a) and (c). 2,2'-MDI and 2,4'-MDI are contained in a total amount of 60 to 85% by mass in the total amount of MDI components; The content of the MDI component is 50 to 85 mass%; (b) is a polyether polyol having a specific number average molecular weight, a specific average functional group number, and a specific oxyethylene group weight; Disclosed are isocyanate compositions. Further, according to Patent Document 1, according to such a polyisocyanate composition for flexible polyurethane foam, the storage stability of the polyisocyanate composition is high, the moldability is good, and the mechanical properties, wet heat compression set and impact resilience are improved. It is disclosed that excellent flexible polyurethane foams are obtained.

Incidentally, MDI is an abbreviation for diphenylmethane diisocyanate (hereinafter referred to as MDI), polymeric MDI is an abbreviation for polymethylene polyphenylene polyisocyanate (hereinafter referred to as p-MDI), and pure MDI is 2,2 It is a generic term for '-MDI, 2,4'-MDI, and 4,4'-MDI.

WO2008/136179

However, in the composition according to Patent Document 1, since the isocyanate component is modified with a polyol, the viscosity increases and the NCO content decreases, so that a flexible polyurethane foam having a low density and excellent elastic performance can be obtained. was very difficult. When making urethane foam, the NCO group of isocyanate reacts with water to generate carbon dioxide gas and foam. There was a problem that many bonds were generated and the hardness of the foam became too high.

Accordingly, one aspect of the present disclosure is to provide a flexible polyurethane foam-forming composition that contributes to the production of a flexible polyurethane foam that has low density, moderate softness, strong mechanical properties, and durability. directed to. In addition, one aspect of the present disclosure is directed to providing a flexible polyurethane foam having low density, moderate softness, strong mechanical properties, and durability.

According to each aspect of the present disclosure, the following (1) to (6) are provided.
(1) a polyol component (A);
a catalyst (B);
a foam stabilizer (C);
a foaming agent (D);
and a polyisocyanate component (E),
The ratio of the foaming reaction rate constant to the resinification reaction rate constant of the catalyst (B) (foaming reaction rate constant/resinization reaction rate constant) is 0.090 or less,
The polyisocyanate component (E) is
diphenylmethane diisocyanate (E-1); and
and an optional polymethylene polyphenylene polyisocyanate (E-2),
In the polyisocyanate component (E),
The content of the diphenylmethane diisocyanate (E-1) is 75% by mass or more and 100% by mass or less with respect to the total amount of the polyisocyanate component (E),
A flexible polyurethane foam-forming composition, wherein the content of the polymethylene polyphenylene polyisocyanate (E-2) is 0% by mass or more and 25% by mass or less with respect to the total amount of the polyisocyanate component (E).

(2) The sum total of the content of 2,2'-diphenylmethane diisocyanate and the content of 2,4'-diphenylmethane diisocyanate in the diphenylmethane diisocyanate (E-1) is The flexible polyurethane foam-forming composition according to (1), which is 20% by mass or more and 60% by mass or less based on the total amount.

(3) The sum total of the content of 2,2′-diphenylmethane diisocyanate and the content of 2,4′-diphenylmethane diisocyanate in diphenylmethane diisocyanate (E-1) is The flexible polyurethane foam-forming composition according to (1) above, which is 30% by mass or more and 50% by mass or less based on the total amount.

(4) A flexible polyurethane foam, which is a foamed molding of the flexible polyurethane foam-forming composition according to any one of (1) to (3) above.

(5) an apparent density of 25 kg/m ³ or more and 40 kg/m ³ or less;
The flexible polyurethane foam according to (4) above, wherein the skinned foam test piece has a 25% compression hardness of 100 N/314 cm ² or less measured according to JIS K6400, Method B.

(6) the elongation measured according to the method described in JIS K6400 is 100% or more;
Tear strength is 4.5 N / cm or more,
The flexible polyurethane foam according to (4) or (5) above, which has a wet heat compressive strain of 25% or less.

According to one aspect of the present disclosure, there is provided a flexible polyurethane foam-forming composition that contributes to the production of a flexible polyurethane foam that has low density, moderate softness, strong mechanical properties, and durability. can be done. In addition, according to one aspect of the present disclosure, it is possible to provide a flexible polyurethane foam having low density, moderate softness, strong mechanical properties, and durability.

Exemplary embodiments for implementing aspects of the present disclosure are described in detail below.
<Flexible polyurethane foam-forming composition>
A flexible polyurethane foam-forming composition according to one aspect of the present disclosure comprises:
a polyol component (A);
a catalyst (B);
a foam stabilizer (C);
a foaming agent (D);
and a polyisocyanate component (E).
The ratio of the foaming reaction rate constant to the resinification reaction rate constant of the catalyst (B) (foaming reaction rate constant/resinization reaction rate constant) is 0.090 or less.
The polyisocyanate component (E) is
diphenylmethane diisocyanate (E-1); and
and an optional polymethylene polyphenylene polyisocyanate (E-2),
In the polyisocyanate component (E),
The content of the diphenylmethane diisocyanate (E-1) is 75% by mass or more and 100% by mass or less with respect to the total amount of the polyisocyanate component (E),
The content of the polymethylene polyphenylene polyisocyanate (E-2) is 0% by mass or more and 25% by mass or less with respect to the total amount of the polyisocyanate component (E).

<<Polyol Component (A)>>
The polyol component (A) undergoes polyaddition with the polyisocyanate component (E) to form a polyurethane. The polyol component (A) is preferably at least one selected from the group consisting of polyether polyols and polyester polyols.
The number average molecular weight of the polyol component (A) is preferably 1,000 or more and 10,000 or less. When the number average molecular weight is 1,000 or more, the flexibility of the obtained foam is further improved. If the number average molecular weight is 10,000 or less, the hardness of the foam will be even better.
The nominal number of functional groups of the polyol component (A) is preferably 2 or more. When the nominal number of functional groups is 2 or more, wet heat compressive strain, which is an index of durability, becomes even better. The nominal number of functional groups means the theoretical average number of functional groups (the number of active hydrogen atoms per molecule) assuming that no side reactions occur during the polyol polymerization reaction.

Examples of polyether polyols include polypropylene ether polyol, polyethylene polypropylene ether polyol (hereinafter referred to as PPG) and polytetramethylene ether glycol (hereinafter referred to as PTG). Examples of polyester polyols include polycondensation type polyester polyols such as adipic acid and diols, and lactone polyester polyols such as polycaprolactone polyols.

From the viewpoint of improving the durability of the resulting foam, the polyol component (A) has a total degree of unsaturation of 0.001 meq. / g or more 0.04 meq. / g or less polyoxyalkylene polyol (A-1) is preferably included. An increase in the total degree of unsaturation of polyol (A-1) means an increase in monool components having unsaturated groups at their terminals. Therefore, the total degree of unsaturation of the polyoxyalkylene polyol (A-1) is 0.04 meq. /g or less, the resulting foam has a higher crosslink density and further improved durability. Further, the total degree of unsaturation of the polyoxyalkylene polyol (A-1) is 0.001 meq. /g or more, the production time can be shortened and the productivity is improved, which is economical.
In the polyoxyalkylene polyol (A-1), the polymerization catalyst is preferably at least one selected from double metal cyanide complex catalysts, phosphazene catalysts, and imino group-containing phosphazenium salts.

The polyol component (A) promotes foam breakage of the flexible polyurethane foam, so it may contain a polyether polyol (A-2) having a polyoxyalkylene chain composed of a copolymer of oxyethylene and oxypropylene. preferable. The polyether polyol (A-2) preferably has a nominal number of functional groups of 2-4.

The oxyethylene unit in the polyether polyol (A-2) is preferably 60% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 80% by mass or less. Durability improves more because an oxyethylene unit is 60 mass % or more and 90 mass % or less. Further, from the viewpoint of storage stability at low temperatures, the copolymer composed of oxyethylene and oxypropylene in the polyether polyol (A-2) is preferably a random copolymer.

The content of the polyether polyol (A-2) is preferably 0.5% by mass or more and 5.0% by mass or less with respect to the polyol component (A). When it is 0.5% by mass or more, the moldability of the foam is further improved. When it is 5.0% by mass or less, the elongation rate of the obtained foam is further improved.

For the polyol component (A), it is preferable to use a polymer polyol obtained by polymerizing a vinyl-based monomer in a polyol by an ordinary method for the purpose of adjusting hardness. Examples of such a polymer polyol include those obtained by polymerizing and stably dispersing a vinyl-based monomer in a polyalkylene polyol such as the above PPG in the presence of a radical initiator. Examples of vinyl-based monomers include acrylonitrile, styrene, vinylidene chloride, hydroxyalkyl methacrylate, and alkyl methacrylate, with acrylonitrile and styrene being preferred. Examples of such polymer polyols include EL-910 and EL-923 manufactured by AGC, and FA-728R manufactured by Sanyo Chemical Industries.

<<catalyst (B)>>
Catalyst (B) includes various urethanization catalysts known in the art. For example, triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N,N',N' , N″-pentamethyldiethylenetriamine, bis-(2-dimethylaminoethyl)ether, triethylenediamine, 1,8-diaza-bicyclo[5.4.0]undecene-7, 1,2-dimethylimidazole, dimethylethanol amines, N,N-diethylethanolamine and the like, N,N-dimethyl-N-hexanolamine, organic acid salts thereof; organic metal compounds such as stannus octoate and zinc naphthenate;
These may be used singly or in combination of two or more.

The content of the catalyst (B) is preferably 0.01% by mass or more and 10% by mass or less with respect to the polyol component (A). When it is 0.01% by mass or more, insufficient curing can be further suppressed, and when it is 10% by mass or less, moldability is further improved.

The ratio of the foaming reaction rate constant to the resinification reaction rate constant of the catalyst (B) (foaming reaction rate constant/resinization reaction rate constant) is 0.090 or less, and is 0.005 or more and 0.080 or less. is preferred, and 0.010 or more and 0.080 or less is more preferred.
The resinification reaction rate constant is a reaction rate constant when forming a urethane bond by reaction between an isocyanate group and a hydroxy group.
Further, the foaming reaction rate constant is the reaction rate constant when forming a urea bond by the reaction between an isocyanate group and water.
Here, when the ratio of the foaming reaction rate constant to the resinification reaction rate constant (foaming reaction rate constant/resinization reaction rate constant) is 0.090 or less, the formation of urethane bonds is promoted to increase the molecular weight. The present inventors presume that the deterioration of moldability can be suppressed by sufficiently progressing.

The resinification reaction rate constant (k1w) is a parameter calculated by the following method. That is, toluene diisocyanate and diethylene glycol are charged so that the [isocyanate group] / [hydroxyl group] (molar ratio) is 1.0, a certain amount of the catalyst component (k1w calculation target) is added, and a certain amount is added in a benzene solvent. Reaction is allowed to occur while maintaining the temperature, and the amount of unreacted isocyanate is measured. Here, assuming that the reaction between toluene diisocyanate and diethylene glycol is first-order with respect to each concentration, the following equation holds.
dx/dt=k(ax) ² (1)
x: concentration of reacted NCO groups (mol/L)
a: Initial concentration of NCO groups (mol/L)
k: reaction rate constant (L/mol h)
t: reaction time (h)

When the initial conditions t=0 and X=0 are substituted into the equation (1) and integrated, the following equation holds.
1/(ax)=kt+1/a (2)
k=ko+KcC (3)
ko: uncatalyzed reaction rate constant (L/mol h)
Kc: catalytic constant (L ² /g·mol·h)
C: catalyst concentration in the reaction system (mol/L)

The reaction rate constant k is obtained from the equation (2) and substituted into the equation (3) to obtain the catalyst constant Kc.
The obtained catalyst constant Kc is divided by the molecular weight (mc) of the catalyst to obtain the resinification reaction rate constant k1w (L ² /g·mol·h), which can be regarded as activity per mass.
Kc/mc=k1w (4)
When the catalyst (B) is a combination of n types (n≧2), the resinification reaction rate constant k1w (L ² /g·mol·h) can be obtained by the formula (5).

W: mass of catalyst (g)

On the other hand, the foaming reaction constant (k2w) is obtained in the same manner as described above by reacting toluenediisocyanate and water in a benzene solvent under the same conditions as in the resinification reaction described above.

<<Foam Stabilizer (C)>>
Usual surfactants are used as the foam stabilizer (C), and organosilicon surfactants can be preferably used. For example, Dow Corning Toray SZ-1327, SZ-1325, SZ-1336, SZ-3601, Momentive Y-10366, L-5309, Evonik B-8724LF2, B-8715LF2, etc. mentioned.
The content of the foam stabilizer (C) is preferably 0.1% by mass or more and 3.0% by mass or less with respect to the polyol component (A).

<<Blowing agent (D)>>
Water is preferred as the blowing agent (D). Water reacts with an isocyanate group to form a highly rigid urea group and generate carbon dioxide gas. The carbon dioxide causes foaming in the flexible polyurethane foam-forming composition, thus forming a urethane foam.

Other blowing agents may be contained together with water. Other blowing agents include, for example, small amounts of low boiling organic compounds such as cyclopentane and isopentane. Alternatively, air, nitrogen gas, liquefied carbon dioxide, or the like may be mixed and dissolved in the undiluted solution using a gas loading device to cause foaming.

The content of the foaming agent (D) is preferably 0.5% by mass or more and 10% by mass or less with respect to the polyol component (A). When obtaining a low-density flexible polyurethane foam having an apparent density of less than 40 kg/m ³ , the content is preferably 3.0% by mass or more and 7.0% by mass or less, more preferably 3.0% by mass or more and 5.5% by mass or less. . If the upper limit is exceeded, the foaming may become difficult to stabilize, and if the lower limit is not reached, the density of the foam may not be lowered sufficiently.

<<Polyisocyanate Component (E)>>
The polyisocyanate component (E) is
diphenylmethane diisocyanate (E-1); and
and an optional polymethylene polyphenylene polyisocyanate (E-2),
In the polyisocyanate component (E),
The content of diphenylmethane diisocyanate (E-1) is 75% by mass or more and 100% by mass or less with respect to the total amount of the polyisocyanate component (E),
The content of the polymethylene polyphenylene polyisocyanate (E-2) is 0% by mass or more and 25% by mass or less with respect to the total amount of the polyisocyanate component (E).

Examples of the polyisocyanate component (E) include 4,4'-diphenylmethane diisocyanate (hereinafter referred to as 4,4'-MDI), 2,4'-diphenylmethane diisocyanate (hereinafter referred to as 2,4'-MDI), 2,2 '-diphenylmethane diisocyanate (hereinafter referred to as 2,2'-MDI), diphenylmethane diisocyanate (hereinafter referred to as MDI), polymethylene polyphenylene polyisocyanate (hereinafter referred to as p-MDI); are mentioned. These may be used alone or in combination of two or more. Examples of modified materials include urethane modified materials, urea modified materials, allophanate modified materials, nurate modified materials, and biuret modified materials.

The MDI (E-1) content of the polyisocyanate component (E) is 75% by mass or more and 100% by mass or less. If the MDI content is less than 75% by mass, the elongation of the flexible polyurethane foam will decrease as the crosslink density increases, and sufficient foam strength will not be obtained.

In addition, the sum of the content of 2,2'-MDI and the content of 2,4'-MDI in MDI (E-1) (hereinafter referred to as the isomer content) is the content of MDI (E-1). It is preferably 20% by mass or more and 60% by mass or less, more preferably 30% by mass or more and 50% by mass or less, relative to the total amount. If it is 60% by mass or less, the reactivity is further improved, the molding cycle can be further shortened, and the increase in the closed cell rate of the foam is further suppressed to prevent problems such as shrinkage after molding. can be further reduced.

<<Molar ratio (NCO group/active hydrogen group)>>
In the flexible polyisocyanate-forming composition, the molar ratio (NCO group/active hydrogen group) of all isocyanate groups to all active hydrogen groups in the active hydrogen group-containing compound containing water is 0.5 or more and 1 It is preferably 0.4 or less (isocyanate index (NCO INDEX) = 50 to 140), more preferably 0.7 or more and 1.2 or less (NCO INDEX = 70 to 120). Within this range, the resulting foam has good durability and good molding cycle.
If the NCO INDEX is 50 or more, the durability can be further improved, and the excessive increase in closed foam can be suppressed. If the NCO INDEX is 140 or less, the molecular weight is quickly increased, and collapse of the foam during foaming is suppressed to a higher degree.

<<other ingredients>>
The flexible polyurethane foam-forming composition optionally contains fillers such as calcium carbonate and barium sulfate, various known additives and auxiliaries such as flame retardants, plasticizers, colorants and antifungal agents. good too.

<Flexible polyurethane foam and its manufacturing method>
A flexible polyurethane foam according to an aspect of the present disclosure is a foamed molded product of the flexible polyurethane foam-forming composition described above. This flexible polyurethane foam provides good ride comfort when used as a cushioning material, for example.
The apparent density of the flexible polyurethane foam is preferably 25 kg/m ³ or more and 40 kg/m ³ or less.
A skinned foam test piece of flexible polyurethane foam (details will be described later) preferably has a 25% compression hardness of 100 N/314 cm ² or less.
The flexible polyurethane foam preferably has an elongation percentage of 100% or more.
The flexible polyurethane foam preferably has a tear strength of 4.5 N/cm or more.
The wet heat compression set of the flexible polyurethane foam is preferably less than 25%.

Next, a method for producing flexible polyurethane foam will be described.
A method for producing a flexible polyurethane foam according to one aspect of the present disclosure includes:
obtaining a mixture by mixing the polyol component (A), the catalyst (B), the foam stabilizer (C), the blowing agent (D), and the polyisocyanate component (E);
and obtaining a flexible polyurethane foam by reacting and foaming the mixture.

Here, each of the components (A) to (E) may be added one by one, or two or more may be mixed in advance and finally all the components may be mixed.
In the former case, there are no restrictions on the order in which components (A) to (E) are added, and any order may be used. Two or more of components (A) to (E) may be added separately and simultaneously.
In the latter case, for example,
obtaining a first liquid with a first premix;
obtaining a second liquid with a second premix;
mixing the first liquid and the second liquid to obtain a mixed liquid.
Here, for example, the first liquid contains a polyol component (A), a catalyst (B), a foam stabilizer (C), and a foaming agent (D), and the second liquid contains an isocyanate component (E ) may consist of only. In this case, the second premixing can be omitted.

It is preferable that the mixture (foaming undiluted solution) is injected into a mold, and then reacted, foamed, and cured.
The temperature of the mold when the mixed liquid is injected into the mold is usually 30° C. or higher and 80° C. or lower, preferably 45° C. or higher and 65° C. or lower. When the mold temperature is 30° C. or higher when the mixed liquid is injected into the mold, the reaction speed is improved and the production cycle can be shortened. When the mold temperature is 80° C. or lower, excessive reaction between water and isocyanate is further suppressed with respect to the reaction between polyol and isocyanate, thereby further suppressing collapse of the foam during foaming.

The curing time for foaming and curing the above-mentioned foaming stock solution is preferably 10 minutes or less, more preferably 7 minutes or less, in consideration of the general production cycle of soft molded foams.

When producing the flexible molded foam, the above components can be mixed using a high-pressure foaming machine, a low-pressure foaming machine, or the like, as in the case of ordinary flexible molded foams.

It is preferable to mix the isocyanate component (E) and the polyol component (A) immediately before foaming. Components (B) to (D) and other components can be mixed in advance with the isocyanate component (E) or the polyol component (A) within a range that does not affect the storage stability and reactivity of the raw materials over time. can. The resulting mixture may be used immediately after mixing, or may be used as needed after being stored. In the case of a foaming device capable of simultaneously introducing more than two components into the mixing section, each of the components (A) to (E), additives, etc. can be individually introduced into the mixing section.

Moreover, the mixing method may be either dynamic mixing in which mixing is performed in the machine head mixing chamber of the foaming machine, or static mixing in which mixing is performed in the liquid feeding pipe, or both may be used in combination. Mixing of a gaseous component such as a physical foaming agent and a liquid component is often performed by static mixing, and mixing of components that can be stably stored as liquids is often performed by dynamic mixing, but the mixing method is not limited to this. As a foaming device that can be used in the production of flexible polyurethane foam, a high-pressure foaming device that does not require solvent cleaning of the mixing section is preferred.

The mixed liquid obtained by such mixing is discharged into a mold, reacted, foamed and cured, and then demolded. It is also preferable to apply a mold release agent to the mold in advance in order to smoothly remove the mold. The mold release agent to be used includes mold release agents commonly used in the field of molding processing.

Although the product after demolding can be used as it is, it is preferable to break the cell membranes of the foam under compression or under reduced pressure by a conventionally known method to stabilize the subsequent product appearance and dimensions.

By the method for producing flexible polyurethane foam described above,
Apparent density of 25 kg/m ³ or more and 40 kg/m ³ or less,
The 25% compression hardness of the skinned foam test piece is 100 N/314 cm ² or less,
a tear strength of 4.5 N/cm or more,
Wet heat compressive strain is less than 25%,
A flexible polyurethane foam can be easily obtained.

EXAMPLES The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples. "Parts" and "%" in the text are based on mass unless otherwise specified.

[Preparation of polyol composition]
(Examples 1-4, Comparative Examples 1-3)
After purging a reactor equipped with a stirrer, a condenser tube, a nitrogen inlet tube, and a thermometer, 97 g of polyol 1, 3.0 g of polyol 2, 1.2 g of catalyst 1, 1.0 g of foam stabilizer 1, A polyol composition (P-1) was obtained by charging 5.4 g of water and stirring at 23° C. for 0.5 hour. Other polyol compositions (P-2 to P-7) were prepared in the same manner as P-1.

Among the raw materials shown in Table 1, the liquid temperature of the isocyanate component (E) and the mixture of all the raw materials other than the isocyanate component (E) (polyol compositions (P-1) to (P-7)) was adjusted to 24 ° C. to Adjusted to 26°C. A predetermined amount of the polyisocyanate component (E) is added to the polyol compositions (P-1) to (P-7), mixed for 5 seconds in a mixer (7000 rpm), and then injected into a mold to form a flexible polyurethane foam. was foamed. Then, it was taken out from the mold and the physical properties of the obtained flexible polyurethane foam were measured. The NCO Index in Table 1 is the ratio of the number of moles of NCO groups to the number of moles of active hydrogen atoms present in the flexible polyurethane foam-forming composition.

[Foaming conditions]
Mold temperature: 60-70°C
Mold shape: 400mm x 400mm x 100mm
Mold material: Aluminum

[raw materials used]
Isocyanate 1: MDI content 89%, isomer content 38%, polyphenylenepolymethylene polyisocyanate content 11%
Isocyanate 2: diphenylmethane diisocyanate with an MDI content of 100% and an isomer content of 55% Isocyanate 3: an MDI content of 70%, an isomer content of 29%, and a polyphenylenepolymethylene polyisocyanate content of 30%
· Polyol 1: Average functional group number = 3.0, hydroxyl value = 24 (mgKOH/g), terminal primary conversion rate = 84 mol%, oxyethylene unit = 14.6% by mass, total unsaturation 0.03 meq. / g of polyoxyethylene polyoxypropylene polyol (manufactured by Tosoh Corporation, trade name: NEF-693)
· Polyol 2: Average functional group number = 3.0, hydroxyl value = 24 (mgKOH/g), terminal primary conversion rate = 51 mol%, oxyethylene unit = 70% by mass, total unsaturation 0.03 meq. / g of polyoxyethylene polyoxypropylene polyol (manufactured by Sanyo Chemical Industries, Ltd., trade name: SANNIX FA-159)
· Polyol 3: Average functional group number = 4.0, hydroxyl value = 28 (mgKOH/g), terminal primary conversion rate = 79 mol%, oxyethylene unit = 80% by mass, total unsaturation 0.01 meq. / g of polyoxyethylene polyoxypropylene polyol (manufactured by Toho Chemical Industry Co., Ltd., trade name: Toho Polyol QB-8000)
・ Catalyst 1: 1,2-dimethylimidazole, [foaming reaction rate constant/resin formation reaction rate constant] = 0.076
- Catalyst 2: triethylenediamine 33% dipropylene glycol solution, [foaming reaction rate constant/resin formation reaction rate constant] = 0.132
・Foam stabilizer 1: Silicone foam stabilizer (manufactured by Momentive, trade name: L-3641LF)
・Foam stabilizer 2: Silicone foam stabilizer (manufactured by Momentive, trade name: L-3627)
・Foam stabilizer 3: Silicone foam stabilizer (manufactured by Momentive, trade name: Y-10366)

[Moldability evaluation]
In the evaluation of moldability in Table 1, A was able to mold a flexible polyurethane foam without shrinkage of the formed urethane molded foam after demolding or without occurrence of roughness on the surface or inside of the foam. B means that phenomena such as shrinkage and surface or internal roughness occurred in the urethane molded foam.

[Apparent density]
It was determined by the method described in JIS K6400.

[25% compression hardness (25% ILD) of skinned foam specimen]
Obtained by B method described in JIS K6400. The skinned foam test piece is a molded foam molded by the above-described method, and refers to a foam in which the skin remains without cutting or the like.

[Tear strength]
It was measured by the method described in JIS K6400.

[Wet heat compression strain]
It was measured by the method described in JIS K6400.

[Growth rate]
It was measured by the method described in JIS K6400.

As shown in Table 1, according to Examples 1 to 4, the value of [foaming reaction rate constant/resinization reaction rate constant] is 0.090 or less, the 25% compression hardness is 100 N/314 cm ² or less, and the tear strength is A flexible polyurethane foam having a tensile strength of 4.5 N/cm or more, an elongation of 100% or more, and a wet heat compressive strain of 25% or less is obtained. On the other hand, according to Comparative Examples 1 and 2, when the value of [foaming reaction rate constant/resinification reaction rate constant] exceeds 0.090, the stability of the cells in the foam is remarkably lowered, and the moldability is poor. Deterioration causes roughness on the surface and inside of the urethane foam. On the other hand, according to Comparative Example 3, the tear strength is less than 4.5 N/cm and the wet heat compressive strain exceeds 25%.
As is clear from the comparison of the above examples and comparative examples, a molded body having a hardness that provides a comfortable ride when used as a seat back material, for example, and having desirable physical properties can be obtained.

Claims (6)

a polyol component (A);
a catalyst (B);
a foam stabilizer (C);
a foaming agent (D);
and a polyisocyanate component (E),
The ratio of the foaming reaction rate constant to the resinification reaction rate constant of the catalyst (B) (foaming reaction rate constant/resinization reaction rate constant) is 0.090 or less,
The polyisocyanate component (E) is
diphenylmethane diisocyanate (E-1); and
and an optional polymethylene polyphenylene polyisocyanate (E-2),
In the polyisocyanate component (E),
The content of the diphenylmethane diisocyanate (E-1) is 75% by mass or more and 100% by mass or less with respect to the total amount of the polyisocyanate component (E),
A flexible polyurethane foam-forming composition, wherein the content of the polymethylene polyphenylene polyisocyanate (E-2) is 0% by mass or more and 25% by mass or less with respect to the total amount of the polyisocyanate component (E). The sum of the content of 2,2'-diphenylmethane diisocyanate and the content of 2,4'-diphenylmethane diisocyanate in the diphenylmethane diisocyanate (E-1) is the total amount of the diphenylmethane diisocyanate (E-1). 20% by mass or more and 60% by mass or less, the flexible polyurethane foam-forming composition according to claim 1. The sum of the content of 2,2'-diphenylmethane diisocyanate and the content of 2,4'-diphenylmethane diisocyanate in the diphenylmethane diisocyanate (E-1) is the total amount of the diphenylmethane diisocyanate (E-1). The flexible polyurethane foam-forming composition according to claim 1, wherein the content is 30% by mass or more and 50% by mass or less. A flexible polyurethane foam, which is a foamed molding of the flexible polyurethane foam-forming composition according to any one of claims 1 to 3. An apparent density of 25 kg/m ³ or more and 40 kg/m ³ or less,
5. The flexible polyurethane foam according to claim 4, wherein the skinned foam test piece has a 25% compression hardness of 100 N/314 cm ² or less measured according to JIS K6400, Method B. The elongation measured according to the method described in JIS K6400 is 100% or more,
Tear strength is 4.5 N / cm or more,
6. The flexible polyurethane foam according to claim 4 or 5, having a wet heat compressive strain of 25% or less.