JPH11116654A - Flexible polyurethane foam and method for producing the same - Google Patents

Abstract

(57) Abstract: A flexible polyurethane foam obtained by reacting an active hydrogen compound with an organic polyisocyanate composition in the presence of a foaming agent, a crosslinking agent, a foam stabilizer, a catalyst and other additives. The active hydrogen compound comprises (a) a polyether triol having a hydroxyl equivalent of 700 or more and 5,000 or less and (ii) a polyether diol having a hydroxyl equivalent of 1,000 or more and 6000 or less.
(B) a mixture weight ratio of 80/20 to 10/90, wherein the organic polyisocyanate composition is
(C) polymethylene polyphenyl isocyanate,
(D) 2,4- and / or 2,6-tolylene diisocyanate is (c) / (d) mixed weight ratio = 65 / 35-8
0/20, wherein the foam has a frequency of 50.
A flexible polyurethane foam whose vibration transmissibility at 0 to 1000 Hz is -15 dB or less. [Effect] Light weight (apparent density = 50 kg / m ³ or less)
Thus, a flexible polyurethane foam having excellent vibration damping performance can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a flexible polyurethane foam. More specifically, the present invention relates to a lightweight polyurethane foam having excellent vibration damping properties and a method for producing the same.

[0002]

2. Description of the Related Art In general, when a polyurethane foam is used as a vibration damping material, it is often difficult to obtain a satisfactory damping property by using a foam alone, and various studies have been made so far. For example, JP-A-1-275617 discloses a polyurethane foam containing asphalt, and JP-A-2-084211 discloses a polyurethane foam using calcium carbonate. However, polyurethane foams containing asphalt and calcium carbonate have problems such as contamination of the molding machine and increase in the weight of the polyurethane foam. JP-A-3-081315 discloses that the hydroxyl equivalent is 500
Polyurethane foams using the following polyether triols and polyether diols,
No. 6561 discloses a polyurethane foam using a polyhydroxyl compound having a hydroxyl equivalent of 30 to 500, and JP-A-6-184264 discloses a polyurethane foam using a polyhydroxyl compound having a hydroxyl equivalent of 500 or less. However, when a polyether having a hydroxyl equivalent of 500 or less is used, there is a problem that the vibration transmissibility at a frequency of 100 to 900 Hz is deteriorated.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and provides a flexible polyurethane foam which is lightweight (apparent density = 50 kg / m ³ or less) and has excellent vibration damping properties, and a method for producing the same. The purpose is to:

[0004]

Means for Solving the Problems The present inventors have found that the above object can be achieved by using a mixture of polyether triol and polyether diol having a specific molecular weight and an organic polyisocyanate composition, and completed the present invention. It led to.

[0005] That is, as an outline of the present invention, a flexible polyurethane foam is prepared by reacting an active hydrogen compound with an organic polyisocyanate composition in the presence of a foaming agent, a crosslinking agent, a foam stabilizer, a catalyst and other additives. When obtaining, as the active hydrogen compound, (a) the hydroxyl equivalent is 700 or more and 50 or more.
A mixture comprising a polyether triol having a hydroxyl equivalent of not more than 00 and (ii) a polyether diol having a hydroxyl equivalent of not less than 1,000 and not more than 6000 and having a mixing weight ratio of (a) / (b) of 80/20 to 10/90. The organic polyisocyanate composition comprises (c) polymethylene polyphenyl isocyanate, (d) 2,4- and / or 2,6-tolylene diisocyanate, and (c) /
(D) using a mixture having a mixing weight ratio of 65/35 to 80/20, a soft foam having a hardness of 70 or less as Asker hardness meter type F and a vibration transmission rate at a frequency of 500 to 1000 Hz of -15 dB or less; The present invention relates to a polyurethane foam and a method for producing the same, which relates to a flexible polyurethane foam having an NCO index of 70 to 90 and a method for producing the same.

That is, the present invention provides the following (1) to (8). (1) A flexible polyurethane foam obtained by reacting an active hydrogen compound with an organic polyisocyanate composition in the presence of a foaming agent, a crosslinking agent, a foam stabilizer, a catalyst and other additives, wherein the active hydrogen compound But (a) a polyether triol having a hydroxyl equivalent of 700 or more and 5,000 or less;
And a mixed weight ratio of (a) / (b) of 80/20 to 10/90.
Wherein the organic polyisocyanate composition comprises (c) polymethylene polyphenyl polyisocyanate, (d) 2,4- and / or 2,6-tolylene diisocyanate, and (c) / (D) a mixture having a mixing weight ratio of 65/35 to 80/20, wherein the flexible polyurethane foam has a frequency of 500 to 1000 Hz.
A flexible polyurethane foam, wherein the vibration transmissibility is -15 dB or less.

(2) The NCO index is from 0.6 to
1.0. The flexible polyurethane foam according to (1), which is 1.0.

(3) The soft polyurethane foam according to (1) or (2) has a hardness of Asker hardness tester type F
Flexible polyurethane foam characterized by having a molecular weight of 70 or less.

(4) (c) The polymethylene polyphenyl polyisocyanate comprises 40 to 50% by weight of 4,4'-diphenylmethane diisocyanate, 0 to 10% by weight of 2,4'-diphenylmethane diisocyanate,
Crude diphenylmethane diisocyanate containing 0 to 2% by weight of 2'-diphenylmethane diisocyanate and 50 to 60% by weight of methylene-bridged polyphenyl polyisocyanate having three or more nuclei, 2,2'-diphenylmethane diisocyanate and 2,4 ' -Diphenylmethane diisocyanate isomer mixture 0 to 50% by weight,
4,4'-diphenylmethane diisocyanate 50-
(D) 2,4- and / or 2,6-tolylene diisocyanate comprising 2,4 and 100% by weight of purified diphenylmethane diisocyanate.
The isomer ratio of-/ 2,6-tolylene diisocyanate is
2,4- and / or 2, which are 100/0 to 65/35
The flexible polyurethane foam according to any one of (1) to (3), which is 6-tolylene diisocyanate.

(5) A process for producing a flexible polyurethane foam obtained by reacting an active hydrogen compound with an organic polyisocyanate composition in the presence of a foaming agent, a crosslinking agent, a foam stabilizer, a catalyst and other additives. The active hydrogen compound comprises (a) a polyether triol having a hydroxyl equivalent of 700 to 5,000, (b) a polyether diol having a hydroxyl equivalent of 1,000 to 6,000, and (a) / (b) ) Is 8
0/20 to 10/90, wherein the organic polyisocyanate composition comprises (c) polymethylene polyphenyl polyisocyanate, (d) 2,4- and / or 2,6-tolylene diisocyanate. And the mixture weight ratio of (c) / (d) is 65/35 to 80/20.
The flexible polyurethane foam has a vibration transmissibility of -15 at a frequency of 500 to 1000 Hz.
A method for producing a flexible polyurethane foam, which is not more than dB.

(6) The NCO index is from 0.6 to
1.0. The method for producing a flexible polyurethane foam according to (5), wherein the value is 1.0.

(7) The soft polyurethane foam according to (5) or (6) has a hardness of Asker hardness tester type F
Is 70 or less.

(8) (c) The polymethylene polyphenyl polyisocyanate is composed of 40 to 50% by weight of 4,4'-diphenylmethane diisocyanate, 0 to 10% by weight of 2,4'-diphenylmethane diisocyanate,
Crude diphenylmethane diisocyanate containing 0 to 2% by weight of 2'-diphenylmethane diisocyanate and 50 to 60% by weight of methylene-bridged polyphenyl polyisocyanate having three or more nuclei, 2,2'-diphenylmethane diisocyanate and 2,4 ' -Diphenylmethane diisocyanate isomer mixture 0 to 50% by weight,
4,4'-diphenylmethane diisocyanate 50-
(D) 2,4- and / or 2,6-tolylene diisocyanate comprising 2,4 and 100% by weight of purified diphenylmethane diisocyanate.
The isomer ratio of-/ 2,6-tolylene diisocyanate is
2,4- and / or 2, which are 100/0 to 65/35
The method for producing a flexible polyurethane foam according to any one of (5) to (7), which is 6-tolylene diisocyanate.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The active hydrogen compound used in the present invention is:
(A) A mixture comprising a polyether triol having a hydroxyl equivalent of 700 or more and 5,000 or less and (ii) a polyether diol having a hydroxyl equivalent of 1,000 or more and 6000 or less.
The mixed weight ratio of / (b) is 80/20 to 10/90. Here, the hydroxyl equivalent is a value obtained by dividing the molecular weight of the polyether polyol by the number of functional groups of the initiator.

First, (a) polyether triol having a hydroxyl equivalent of 700 or more and 5000 or less will be described.

The polyether triol (a) is obtained by adding one or more alkylene oxides to an initiator having 3 functional groups by a conventional method so that the hydroxyl equivalent becomes 700 or more. is there. In the above polyether triol (a), the number of functional groups is 3
Examples of the initiator include glycerin, triethylene glycol, trimethylolpropane and the like.
Examples of the alkylene oxide to be added to the initiator include propylene oxide, ethylene oxide, butylene oxide, and styrene oxide. The hydroxyl equivalent of (a) is preferably in the range of 700 or more and 5000 or less. When the hydroxyl equivalent of the polyether triol (a) is smaller than 700,
Vibration transmissibility tends to be poor, and if it exceeds 5,000, there is a problem that the viscosity of the polyether polyol tends to increase.

Next, (b) the hydroxyl equivalent is 1000
The polyether diol which is more than 6000 and not more than 6000 will be described. The polyether diol (b) is obtained by adding one or more alkylene oxides to an initiator having 2 functional groups by a conventional method so that the hydroxyl equivalent becomes 1000 or more.

In the above polyether diol (b), examples of the initiator having 2 functional groups include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol and the like. Examples of the alkylene oxide to be added to the initiator include propylene oxide, ethylene oxide, butylene oxide, and styrene oxide. The hydroxyl equivalent of (b) is preferably in the range of 1000 or more and 6000 or less. When the hydroxyl equivalent of the polyether diol (b) is smaller than 1000, the vibration transmissibility tends to be poor, and when it is larger than 6000, the viscosity of the polyether polyol tends to be high. .

The mixing ratio is (a) / (b)
Is in the range of 80/20 to 10/90.
If the mixture weight ratio of (a) is more than 80, the foam tends to shrink sharply and molding failure tends to occur. If the mixing weight ratio of (a) is less than 10, the foam tends to collapse and the foam is less likely to foam.

The active hydrogen compound of the present invention can be obtained by polymerizing an ethylenically unsaturated compound such as acrylonitrile or styrene in the presence of the above-mentioned polyether triol (a) and / or polyether diol (b) to obtain polyacrylonitrile, A polymer-dispersed polyol obtained by dispersing polystyrene, a copolymer thereof, or the like in the above-mentioned polyether triol (a) and / or polyether diol (b), a so-called polymer polyol (trade name), can also be suitably used.

The organic polyisocyanate used in the present invention may be mixed at a specific ratio as described below.
And (d) a mixture of isocyanates. That is,
The organic polyisocyanate composition comprises (c) polymethylene polyphenyl polyisocyanate, (d) 2,4- and / or 2,6-tolylene diisocyanate, and a mixed weight of (c) / (d) The ratio is 65 / 35-8
0/20 mixture.

First, (c) polymethylene polyphenyl polyisocyanate will be described. The polymethylene polyphenyl polyisocyanate (c) is usually a mixture of compounds as exemplified below. In the present invention, preferably, for example, 4,4′-diphenylmethane diisocyanate (hereinafter, diphenylmethane diisocyanate is referred to as MDI) is 40 to 50% by weight,
0-10% by weight of 4'-MDI, 0 of 2,2'-MDI
A crude MDI which is a composition containing 50 to 60% by weight of a methylene-bridged polyphenyl polyisocyanate having 3 or more nuclei, 2,2'-MDI and 2,2'-MDI;
0-50% by weight of the 4'-MDI isomer mixture, 4,4 '
-Purified MD comprising 50 to 100% by weight of MDI
And a mixture consisting of More preferably, a mixture in which the mixture weight ratio of the crude MDI / purified MDI is 50/50 to 30/70.

Next, (d) 2,4- and / or 2,6-
The isomer ratio of tolylene diisocyanate (hereinafter, tolylene diisocyanate is referred to as TDI) is not particularly limited, and does not impair the effects of the present invention. , 4-TDI
/ 2,6TDI = 100/0 to 65/35 is preferable.

The above (c) and (d) are used as a mixture, and the mixing weight ratio (c) / (d) is 65/35 to 80.
/ 20. When the proportion of 2,4- and / or 2,6-TDI in the above (d) is more than 35, the curing speed of the flexible polyurethane foam is deteriorated, and the productivity tends to be deteriorated. When the proportion of 2,4- and / or 2,6-TDI in (d) is less than 20, the expansion ratio tends to decrease, and the flow of the raw material liquid in the mold becomes poor, resulting in poor molding. The rate tends to increase.

As the blowing agent in the present invention, water is used as the only blowing agent. The amount of water used is preferably 4.0 to 6.5 parts by weight, more preferably 5.0 to 6.0 parts by weight, per 100 parts by weight of the active hydrogen compound. When the water content is less than 4.0 parts by weight, the expansion ratio of the flexible polyurethane foam tends to decrease and the density tends to increase,
If the amount is more than 6.5 parts by weight, there is a problem that the curing reaction of the flexible polyurethane foam is deteriorated, and the productivity tends to be lowered and the moldability tends to be deteriorated.

The structure of the crosslinking agent used in the present invention is not particularly limited, but polyhydric alcohols such as ethylene glycol and propylene glycol, or those obtained by adding a small amount of alkylene oxide thereto, diethanolamine, triethanolamine and the like can be used. Amines or those obtained by adding a small amount of alkylene oxide thereto can be used alone or in combination. The amount used is 0.1 to 10 parts by weight per 100 parts by weight of the active hydrogen compound.
More preferably, it is 0.5 to 5 parts by weight.

When the amount is less than 0.1 part by weight, the curing property of the foam surface tends to deteriorate,
If the amount is more than 10 parts by weight, the foam expansion ratio tends to decrease and the density tends to increase, which is not preferable.

The foam stabilizer used in the present invention is a known organic silicon-based surfactant (polysiloxane-polyoxyalkylene copolymer), for example, a trade name of Dow Corning Toray; SRX- 253, SRX-274
C, SF-2961, SF-2962, SF-2969
Etc., and product names manufactured by Nippon Unicar; L-5309,
L-5307, L-5305, L-3600 and the like can be used. The amount used is 0.1 to 5 parts by weight per 100 parts by weight of the active hydrogen compound. Preferably it is 0.1 to 3 parts by weight.

The catalyst in the present invention may be a known one and is not particularly limited. Examples thereof include amine catalysts such as triethylenediamine, N-methylmorpholine and N-ethylmorpholine, tin octylate and tin oleate. And organometallic catalysts such as dibutyltin dilaurate. These catalysts can be used alone or as a mixture.
The amount to be used is 0.1 per 100 parts by weight of the active hydrogen compound.
001 to 5 parts by weight, preferably 0.1 to 5 parts by weight.

As other additives, a flame retardant, a coloring agent, an antioxidant, an antioxidant and the like can be used as required.

Although the method for producing the flexible polyurethane foam of the present invention is not particularly limited, usually, an active hydrogen compound, a foaming agent, a crosslinking agent, a foam stabilizer, a catalyst and other additives are mixed in advance to prepare a resin premix. Thereafter, the mixture is mixed with the organic polyisocyanate at a predetermined ratio, injected into a mold, and reacted and foamed. The NCO index (equivalent ratio of isocyanate groups in the organic polyisocyanate composition to active hydrogen in the resin premix = NCO / H) is 0.
The range is preferably from 6 to 1.0, and more preferably from 0.7 to 0.9. When the NCO index is smaller than 0.6, the density of the flexible polyurethane foam increases, and the curing property of the foam surface tends to deteriorate. When the NCO index is larger than 1.0, the vibration transmissibility tends to be deteriorated. After pouring into a mold, the mixture is allowed to react and cure in an atmosphere at room temperature to 100 ° C. for 3 to 30 minutes, and then the flexible polyurethane foam is taken out from the mold.

The hardness of the flexible polyurethane foam of the present invention is generally 70 or less, preferably 50 or less, as measured by an Asker hardness tester type F. When the foam hardness exceeds 70, the vibration transmissibility becomes larger than -15 dB, and the vibration damping performance tends to deteriorate. Here, the foam hardness is 500 mm ×
The value indicated by the hardness tester when the Asker hardness tester type F is placed on a 500 mm × 20 mm foam. The vibration transmissibility of the flexible polyurethane foam of the present invention is measured and evaluated by the following method. More specifically, a foam having a thickness of 20 mm and a vinyl chloride resin mat having a thickness of 2 mm are placed in this order on an iron plate as a vibration source, and vibration is applied at a frequency of 10 to 1000 Hz. Find the displacement. The lower the vibration transmissibility, the better the vibration suppression performance.

[0033]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

(1) Preparation of resin premix Distilled water or ion-exchanged water was added to 100 parts by weight of a mixture composed of polyether triol and polyether diol.
5 parts by weight, 0.5 part by weight of a foam stabilizer A (manufactured by Dow Corning Toray Co., Ltd., trade name: SF-2969), and a foam stabilizer B (Toray
(Product name: SRXF-274C, manufactured by Dow Corning)
0.5 parts by weight, 0.6 parts by weight of amine catalyst A (manufactured by Active Materials Chemical Co., trade name: Minico L-1020), and 0 parts by weight of amine catalyst B (manufactured by Active Materials Chemical Company, trade name: TMDA).
1 part by weight, 0.3 parts by weight of amine catalyst C (trade name: Dabco X-DM, manufactured by Sankyo Air Products), 1.0 part by weight of crosslinking agent (trade name: KL-210, manufactured by Mitsui Toatsu Chemicals, Inc.) The mixture was stirred and mixed at a ratio of 2 to obtain a resin premix.

(2) Preparation of Organic Polyisocyanate Composition 50 parts by weight of dissolved 4,4′-MDI was added to crude MDI
(Mitsui Toatsu Chemical Co., trade name Cosmonate M-20
0: 4,4′-MDI = 43 wt%, 2,4′-MDI
= 2 wt%, 2,2′MDI = 1 wt%, trinuclear or higher methylene-crosslinked polyphenyl polyisocyanate = 54 w
(t%) 75 parts by weight of a polymethylene polyphenylisocyanate consisting of a mixture of 50 parts by weight and TDI (trade name: T-80: 2,4-TDI = 80 wt., manufactured by Mitsui Toatsu Chemicals, Inc.)
%, 2,6-TDI = 20 wt%) to prepare an organic polyisocyanate composition A.

An organic polyisocyanate composition B comprising a mixture of 60 parts by weight of dissolved 4,4'-MDI and 40 parts by weight of crude MDI (trade name: Cosmonate M-200, manufactured by Mitsui Toatsu Chemicals, Inc.) is prepared. did.

50 parts by weight of polymethylene polyphenyl isocyanate comprising a mixture of 60 parts by weight of dissolved 4,4'-MDI and 40 parts by weight of crude MDI (trade name: Cosmonate M-200, manufactured by Mitsui Toatsu Chemicals, Inc.) And 50 parts by weight of TDI (trade name: T-80, manufactured by Mitsui Toatsu Chemicals, Inc.) were mixed to prepare an organic polyisocyanate composition C.

65 parts by weight of polymethylene polyphenylisocyanate consisting of a mixture of 50 parts by weight of dissolved 4,4'-MDI and 50 parts by weight of crude MDI (trade name: Cosmonate M-200, manufactured by Mitsui Toatsu Chemicals, Inc.) And 35 parts by weight of TDI (trade name: T-80, manufactured by Mitsui Toatsu Chemicals, Inc.) were mixed to prepare an organic polyisocyanate composition D.

(3) Mold foaming The resin premix and the organic polyisocyanate adjusted as described above were vigorously stirred and mixed at the NCO index shown in Tables 1 and 4 for 4 seconds, and 500 mm adjusted to 60 ± 2 ° C. Into a mold of × 500mm × 20mm,
The reaction was solidified for minutes. After 5 minutes, the polyurethane foam was taken out of the mold, and the foam hardness and the vibration transmissibility were measured.

Examples 1 to 7 and Comparative Examples 1 to 7 The results of Examples 1 to 7 and Comparative Examples 1 to 7 were carried out by changing the composition of polyether triol and polyether diol, and the composition of the organic polyisocyanate. .

[0041]

[Table 1] (Note) Comparative Example 3: Evaluation is not possible due to severe shrinkage of the foam and molding is not possible. Comparative Example 4: Foaming is not possible due to cell collapse. Comparative Example 6: Evaluation is impossible due to severe shrinkage of the foam and cannot be molded. Comparative Example 7: The curing speed of the foam is slow and cannot be removed from the mold

[0042]

[Table 2] (Note) Polyethertriol A: hydroxyl equivalent = 2330, EO content = 13% by weight Polyethertriol B: hydroxyl equivalent = 2000, EO content = 15% by weight Polyethertriol C: hydroxyl equivalent = 1700, EO content = 14% % Polyether triol D: hydroxyl equivalent = 1000, EO content = 8% by weight Polyether triol E: hydroxyl equivalent = 330, EO content = 0% by weight Polyether diol A: hydroxyl equivalent = 1500, EO content = 20% by weight

[0043]

According to the present invention, in the production of a flexible polyurethane foam, (a) a polyethertriol having a hydroxyl equivalent of from 700 to 5,000 and (b) a hydroxyl equivalent of 1,000, as active hydrogen compounds.
At least 6000 or less and a mixing weight ratio of (a) / (b) of 80/20 to 10 /
90, and as an organic polyisocyanate composition, (c) polymethylene polyphenyl isocyanate, (d) 2,4- and / or 2,6-tolylene diisocyanate, and (c) / (d) By using a mixture having a mixing weight ratio of 65/35 to 80/20, the compound has excellent vibration damping performance such that the vibration transmissibility at a frequency of 500 to 1000 Hz is -15 dB or less,
In addition, it has become possible to produce lightweight and flexible polyurethane foam.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08G 101: 00) C08L 75:04 (72) Inventor Kunio Sasaoka 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Mitsui Chemicals, Inc. (72 Inventor Seijiro Sakai 1190 Kasama-cho, Sakae-ku, Yokohama City, Kanagawa Prefecture Inside Mitsui Chemicals, Inc.

Claims (8)

[Claims] 1. A flexible polyurethane foam obtained by reacting an active hydrogen compound with an organic polyisocyanate composition in the presence of a foaming agent, a crosslinking agent, a foam stabilizer, a catalyst and other additives. The hydrogen compound comprises (a) a polyether triol having a hydroxyl equivalent of 700 or more and 5,000 or less, and (ii) a polyether diol having a hydroxyl equivalent of 1,000 or more and 6000 or less,
And the mixed weight ratio of (a) / (b) is 80/20 to 10 /
90, wherein the organic polyisocyanate composition comprises (c) polymethylene polyphenyl polyisocyanate, (d) 2,4- and / or 2,6-tolylene diisocyanate, and (c) / (D) is a mixture having a mixing weight ratio of 65/35 to 80/20,
The flexible polyurethane foam has a frequency of 500 to 1000.
A flexible polyurethane foam having a vibration transmissibility at -15 Hz or less. 2. An NCO index of 0.6 to 1.0.
The flexible polyurethane foam according to claim 1, wherein 3. The flexible polyurethane foam according to claim 1 or 2, wherein the hardness of the flexible polyurethane foam is 70 or less as measured by an Asker hardness tester type F. (C) the polymethylene polyphenyl polyisocyanate is composed of 40 to 50% by weight of 4,4′-diphenylmethane diisocyanate, 0 to 10% by weight of 2,4′-diphenylmethane diisocyanate, and 0,2% of 2,2′-diphenylmethane diisocyanate; , A crude diphenylmethane diisocyanate containing 50 to 60% by weight of a methylene-bridged polyphenyl polyisocyanate having 3 or more nuclei, 2,2'-diphenylmethane diisocyanate and 2,2'-diphenylmethane diisocyanate.
A mixture with purified diphenylmethane diisocyanate containing 0 to 50% by weight of a 4'-diphenylmethane diisocyanate isomer mixture and 50 to 100% by weight of 4,4'-diphenylmethane diisocyanate, and (d) 2,4- and / or Or 2,6-tolylene diisocyanate is 2,4- and / or 2,6-tolylene diisocyanate in which the isomer ratio of 2,4- / 2,6-tolylene diisocyanate is 100/0 to 65/35. The flexible polyurethane foam according to any one of claims 1 to 3, which is an isocyanate. 5. A process for producing a flexible polyurethane foam obtained by reacting an active hydrogen compound with an organic polyisocyanate composition in the presence of a foaming agent, a crosslinking agent, a foam stabilizer, a catalyst and other additives. The active hydrogen compound is
(A) a polyether triol having a hydroxyl equivalent of 700 or more and 5,000 or less, and (b) a polyether diol having a hydroxyl equivalent of 1,000 or more and 6000 or less, and having a mixed weight ratio of (a) / (b) of 80.
/ 20 to 10/90, wherein the organic polyisocyanate composition comprises (c) polymethylene polyphenyl polyisocyanate, (d) 2,4- and / or 2,
6-tolylene diisocyanate, and (c)
/ (D) is a mixture having a mixing weight ratio of 65/35 to 80/20, wherein the flexible polyurethane foam has a frequency of 5
A method for producing a flexible polyurethane foam, wherein a vibration transmissibility at 00 to 1000 Hz is -15 dB or less. 6. An NCO index of 0.6 to 1.0.
The method for producing a flexible polyurethane foam according to claim 5, wherein 7. A method for producing a flexible polyurethane foam, wherein the hardness of the flexible polyurethane foam according to claim 5 or 6 is 70 or less by Asker hardness tester type F. 8. The polymethylene polyphenyl polyisocyanate comprises 4,4'-diphenylmethane diisocyanate 40 to 50% by weight, 2,4'-diphenylmethane diisocyanate 0 to 10% by weight, and 2,2'-diphenylmethane diisocyanate 0. , A crude diphenylmethane diisocyanate containing 50 to 60% by weight of a methylene-bridged polyphenyl polyisocyanate having 3 or more nuclei, 2,2'-diphenylmethane diisocyanate and 2,2'-diphenylmethane diisocyanate.
A mixture with purified diphenylmethane diisocyanate containing 0 to 50% by weight of a 4'-diphenylmethane diisocyanate isomer mixture and 50 to 100% by weight of 4,4'-diphenylmethane diisocyanate, and (d) 2,4- and / or Or 2,6-tolylene diisocyanate is 2,4- and / or 2,6-tolylene diisocyanate in which the isomer ratio of 2,4- / 2,6-tolylene diisocyanate is 100/0 to 65/35. The method for producing a flexible polyurethane foam according to any one of claims 5 to 7, which is an isocyanate.