JP2006008774A - Flexible polyurethane foam and method for producing the same - Google Patents

Abstract

When used as a seat cushion pad for an automobile, it has a high hysteresis loss while maintaining a resonance peak position at an equivalent level without greatly changing hardness and rebound resilience, and at 2 to 4 Hz. A flexible polyurethane foam molded article in which the sense of vibration of the body (so-called leopard feeling) is sufficiently reduced, and a method for producing the same are provided.
In the method for producing a flexible polyurethane foam, a polyol component containing at least a polyol compound, a reaction catalyst, and a foam stabilizer and an isocyanate component are mixed and foamed and cured using a foaming agent to form a polyurethane foam. A method for producing a flexible polyurethane foam, comprising hexamethyldisiloxane as a foaming agent.
[Selection figure] None

Description

  The present invention relates to a flexible polyurethane foam and a method for producing the same. In particular, the flexible polyurethane foam of the present invention is suitable for a seat cushion pad for a vehicle that vibrates during use, particularly an automobile.

  In general, flexible polyurethane foam is widely used for seat cushion materials for automobiles, cushion materials for furniture, and the like by utilizing the cushioning properties. A flexible polyurethane foam has a comfortable surface because of its soft surface, and is less likely to cause fatigue to the driver even when driving for a long time. A seat cushion pad made of a flexible polyurethane foam is known.

  Conventionally, in order to improve the ride comfort of a seat cushion for automobiles, a vibration frequency range (4 to 10 Hz: vibration of 6 Hz as an evaluation value) that a person feels uncomfortable with respect to the vibration transmissibility characteristics of JASO B-407. It is said that it is effective to greatly reduce the transmission rate (usually adopted). In particular, vibrations around 6 Hz are said to be the frequency that causes car sickness. Therefore, development has been carried out to keep the vibration transmission rate low even in automobile seat cushion pads made of urethane foam moldings. It was.

  However, the conventional seat cushion pad with a low vibration transmissibility at 6 Hz has a large resonance magnification (resonance peak) appearing at 2 to 4 Hz in the vibration transmissibility characteristics, so that the occupant is seated on the vehicle seat cushion. When running, the sense of stability of the body was lost due to the vibration of the vehicle body, and the sensation of the body swinging up and down (so-called leopard feeling) could not be sufficiently prevented.

  For these reasons, seat cushion pads for vehicles, including automobiles, not only keep vibration transmission rates near 6 Hz low, but also improve safety during driving operations in order to reduce occupant sickness and fatigue. (Improved stability when seated on the seat cushion) is also necessary, and it is considered preferable to exhibit a low vibration transmissibility even in a wider range of frequencies.

  However, in general, in terms of vibration engineering, the vibration transmissibility characteristic curve (vertical axis: vibration transmissibility, horizontal axis: frequency) is reduced when the resonance magnification at 2-4 Hz of the vibration transmissibility characteristic is lowered. The vibration transmissibility at a relatively high frequency (for example, 6 Hz) related to sex increases, and the vibration transmissibility characteristic curve becomes a broad curve as a whole. That is, in the vibration transmissibility characteristic curve, the decrease in vibration transmissibility and the decrease in resonance magnification are in a trade-off relationship.

  Up to now, as an attempt to lower the resonance magnification at 2 to 4 Hz of vibration transmissibility characteristics, a seat cushion pad made of a flexible polyurethane foam focused on a specific physical property value (for example, see Patent Document 1), fluorine having a hydrophilic group Flexible polyurethane foam using a surfactant as a foam stabilizer (for example, see Patent Document 2), and flexible polyurethane foam to which polydimethylsiloxane having 7 to 9 silicon atoms is added in the production process (for example, Patent Document 3) Reference). However, none of these methods has yet been recognized to decrease the resonance magnification enough to completely solve the above problems.

  In addition, a flexible polyurethane foam (see, for example, Patent Document 4) that attempts to lower the resonance magnification by using a specific siloxane compound as a foam stabilizer is also known. However, in this flexible polyurethane foam, the hysteresis loss that is an index of the vibration absorption capability is still low, and a sufficiently high hysteresis loss and a low resonance magnification cannot be achieved at the same time. Moreover, in this flexible polyurethane foam, what has toluene diisocyanate (TDI) as a main component as an isocyanate compound is disclosed, but toluene diisocyanate (TDI) is designated as a specific chemical substance, such as diphenylmethane diisocyanate (MDI). There is a need for isocyanate compounds that are free from problems in the working environment.

Therefore, in the above-described method, it is difficult to respond to a further improvement request for a seat cushion pad made of a flexible polyurethane foam in the technical field of automobiles in which further improvement is always required.
Japanese Patent Laid-Open No. 11-146821 JP-A-11-322875 JP 2001-151841 A JP 2001-139653 A

  Therefore, the object of the present invention is to have a high hysteresis loss while maintaining the resonance peak position at the same level without greatly changing the hardness and impact resilience when used as a seat cushion pad for automobiles, and An object of the present invention is to provide a flexible polyurethane foam molded article in which the resonance magnification at 2 to 4 Hz is reduced, and the sense that the body shakes up and down (so-called hoko feeling) is sufficiently reduced, and a method for producing the same.

  In order to achieve the above-mentioned object, the present inventors have intensively studied the material constituting the flexible polyurethane foam molded body. As a result, the above object is achieved by using the flexible polyurethane foam molded body and the production method thereof as described below. The present inventors have found that this can be done and have completed the present invention.

  That is, the present invention is a method for producing a flexible polyurethane foam by mixing a polyol component containing at least a polyol compound, a reaction catalyst, and a foam stabilizer and an isocyanate component, and foaming and curing using a foaming agent to form a polyurethane foam. Hexamethyldisiloxane is included as the foam stabilizer.

  According to the molded product of the flexible polyurethane foam of the present invention, as shown in the results of Examples, hardness and rebound resilience can be obtained by using a method for producing a flexible polyurethane foam characterized by containing hexamethyldisiloxane as a foam stabilizer. A flexible polyurethane foam molded article in which the resonance peak position is maintained at an equivalent level and the resonance magnification at 2 to 4 Hz is reduced can be obtained without greatly changing the rate. Although the details of the reason why the flexible polyurethane foam molded article using the above component as a foaming agent develops such properties are not clear, by using hexamethyldisiloxane as a foam stabilizer, the viscosity, specific gravity of hexamethyldisiloxane, It is considered that the refractive index and the like act as factors, and as a result, it is presumed that the polyurethane foam preferably acted on the resonance frequency, resonance magnification, and rebound resilience. On the other hand, when other polydimethylsiloxane compounds such as octamethyltrisiloxane and decamethyltetrasiloxane having a molecular chain extended from hexamethyldisiloxane are used instead of hexamethyldisiloxane, the resonance magnification at 2 to 4 Hz is used. It is not possible to obtain a sufficient reduction effect.

  In the flexible polyurethane foam, the addition amount of the hexamethyldisiloxane is 0.01 to 10 parts by weight with respect to 100 parts by weight of the polyol compound. The addition amount of the hexamethyldisiloxane is more preferably 0.1 to 7 parts by weight, and particularly preferably 1 to 5 parts by weight. If the amount of hexamethyldisiloxane is less than 0.01 parts by weight, the effect of reducing the resonance magnification tends to be small. On the other hand, if the amount is larger than 10 parts by weight, the cost increases, which is not preferable.

  Further, the present invention is characterized in that diphenylmethane diisocyanate is contained in an amount of 10 to 100% by weight in the total monomer component of the isocyanate component. The diphenylmethane diisocyanate is preferably contained in an amount of 60 to 100% by weight, and more preferably 80 to 100% by weight. By increasing the ratio of diphenylmethane diisocyanate (MDI) in the total monomer component of the isocyanate component, the vapor pressure is reduced and the working environment and safety are improved.

  The flexible polyurethane foam obtained by the production method of the present invention is particularly suitable for a vehicle having vibration during use, particularly for a seat cushion pad for automobiles. Moreover, when using the flexible polyurethane foam obtained by this invention as a seat cushion pad, the well-known general method used for seat cushion shaping | molding can be applied suitably.

  According to the method for producing a flexible polyurethane foam of the present invention, by containing hexamethyldisiloxane as a foam stabilizer, the resonance peak position is maintained at the same level without greatly changing the hardness and rebound resilience, and 25% or more. A flexible polyurethane foam molded body having a high hysteresis loss and having a reduced resonance magnification at 2 to 4 Hz is obtained. For this reason, when the flexible polyurethane foam obtained in the present invention is applied to a seat cushion pad in particular, it not only reduces occupant's car sickness and fatigue, but also reduces the sense that the body swings up and down (so-called leopard feeling). Yes, it improves safety during driving.

  The flexible polyurethane foam in the present invention is generally obtained by a reaction of a polyol component containing a polyol compound and a polyisocyanate component containing an isocyanate compound in the presence of a foaming agent component, but may be appropriately synthesized by other methods. Moreover, you may use suitably the well-known reaction catalyst generally used for polyurethane manufacture, a crosslinking agent, a foam stabilizer, other additives, etc.

  The flexible polyurethane foam of the present invention is a method for producing a flexible polyurethane foam comprising mixing a polyol component containing at least a polyol compound, a reaction catalyst, and a foam stabilizer and an isocyanate component, and foaming and curing the foam component using the foaming agent. In the above, it is a flexible polyurethane foam obtained by using water and at least one perfluorocarbon compound as the foaming agent.

  There are no particular restrictions on the type of polyol compound used in the flexible polyurethane foam of the present invention. As the polyol compound of the present invention, polyoxyalkylene glycol is preferable because it is easy to adjust.

  As the polyol compound, a polyether polyol obtained by adding an alkylene oxide to a polyfunctional alcohol compound as an initiator is usually used.

  Examples of the polyfunctional alcohol compound include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, triethanolamine, diethanolamine, and compounds obtained by adding a small amount of alkylene oxide to these.

  Examples of alkylene oxides that undergo addition polymerization to polyfunctional alcohol compounds include those having 2 or more carbon atoms, such as ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, and styrene. And oxides. Among these alkylene oxides, those in which propylene oxide and / or butylene oxide and ethylene oxide are used in combination are preferable because of low cost and good characteristics of the obtained seat cushion pad. In particular, those containing 3 to 50% by weight, more preferably 3 to 25% by weight of an oxyethylene unit in which ethylene oxide is a ring-opening unit are preferable.

  The polyoxyalkylene glycol may be a random polymer, block polymer or alternating copolymer of the alkylene oxide, but those containing an oxyethylene unit at the terminal are preferable because of good reactivity with isocyanate groups. The terminal primary ratio (terminal oxyethylene unitization ratio) is preferably 3% by weight or more, more preferably 5% by weight or more, particularly preferably 10 to 20% of the oxyalkylene unit of the polyoxyalkylene glycol. % By weight.

  The molecular weight between crosslinks (molecular weight per hydroxyl group) of such a polyoxyalkylene polyol is usually preferably about 1000 to 4000 for adjusting the hysteresis loss. In particular, those having a molecular weight between crosslinks of 1500 to 2800 are preferable for adjusting the hysteresis loss.

  In the present invention, a polymer polyol in which polymer particles are dispersed in the form of fine particles in a polyol component may be used.

  Examples of the polymer particles include particles such as addition polymerization polymers such as homopolymers or copolymers of vinyl monomers such as acrylonitrile, styrene, alkyl methacrylate, and alkyl acrylate, and condensation polymerization polymers such as polyester, polyurea, and melamine resin. Can be given. Of these, acrylonitrile and homopolymers or copolymers of styrene are preferred. A homopolymer of acrylonitrile is particularly preferable. As the polymer particles, a system containing acrylonitrile polymer fine particles is preferable because the moldability of the seat cushion pad is good.

  The proportion of the polymer particles in the entire polyol component is economically inconvenient if the proportion is too large, and is preferably 40% by weight or less, more preferably 20% by weight or less. In order to effectively improve physical properties such as hardness and durability of the seat cushion pad, it is preferable that the content of the polymer particles in the entire polyol component is 1% by weight or more, further 2% by weight or more.

  The method for introducing such polymer particles into the polyol component is not particularly limited. For example, when the polymer particles are an addition polymerization polymer, in the polyol such as polyoxyalkylene polyol, in the presence of a radical polymerization initiator, By polymerizing vinyl monomers such as styrene and acrylonitrile, it can be stably dispersed in the polyol component. Polymer polyols (POP) are commercially available from Mitsui Chemicals, Asahi Glass, etc., and can be suitably used.

  Both the polyether polyol and the polyoxyalkylene polyol constituting the polymer polyol preferably have a lower terminal unsaturated group concentration. Specifically, the terminal unsaturated group concentration should be 0.1 meq / g or less. Is preferred. When the unsaturated group concentration becomes high, the compression set of the flexible polyurethane foam increases, and problems such as a decrease in durability occur.

  Examples of the polyisocyanate compound in the present invention include various aromatic, alicyclic and aliphatic polyisocyanate compounds having two or more isocyanate groups, which are usually used in the production of flexible polyurethane foams. A modified polyisocyanate compound obtained by modifying an isocyanate compound can be used. Two or more polyisocyanate compounds may be used in combination.

  Specific examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) (purified diphenylmethane diisocyanate (p-MDI), crude MDI (c-MDI)), and the like. Examples include aliphatic or alicyclic polyisocyanates such as xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and the modified products include prepolymer type modified products, isocyanurate type modified products, and urea type modified products of polyisocyanate compounds. And carbodiimide-type modified products. Among these, diphenylmethane diisocyanate and crude MDI have high reactivity, good seat cushion pad characteristics, low volatility, high safety compared to TDI, etc., low cost, etc. It is preferable for the reason. Toluene diisocyanate has a 2,4-substituted product and a 2,6-substituted product, and the use of a mixture of these is preferred, and the 2,4-substituted / 2,6-substituted product mixture ratio is 90 / 10-10. The use of a 60/40 mixture is preferred. Furthermore, it is more preferable to use a blend of toluene diisocyanate: crude MDI in a weight ratio of 0: 100 to 40:60, particularly preferably 0: 100 to 20:80.

  Hexamethyldisiloxane used as a foam stabilizer in the present invention may be used alone or in combination, and two or more kinds may be used in combination with other general foam stabilizers.

  As other general foam stabilizers, those used in the production of ordinary flexible polyurethane foams can be used without particular limitation. Examples thereof include various foam stabilizers such as polyalkylsiloxane (polydimethylsiloxane) / polyoxyalkylene copolymer. The amount used of the total foam stabilizer component is usually 0.01 to 10 parts by weight (based on the active ingredient in the case of a foam stabilizer diluted with a plasticizer or the like) with respect to 100 parts by weight of the polyol component. .

  As a highly active silicone-based foam stabilizer, it can be used in combination with known foam stabilizers such as polydimethylsiloxane and its derivatives as appropriate. Commercially available products are preferably used as the highly active silicone-based foam stabilizer. Specifically, for example, SF2965, SF2962, SF2904, SF2908, SRX294A (manufactured by Toray Dow Corning Silicone), L-5366, L-5309 (Manufactured by Nippon Unicar Co., Ltd.), B8680 (manufactured by Gold Schmidt), etc. are commercially available. It is particularly effective to use a foam stabilizer having a surface tension reducing ability (difference in surface tension before and after addition to the polyol component) of about 1 (dyne / cm). For example, SF2965, SF2962, B8680, L-5366 L-5309 is particularly preferred.

  In the method for producing a flexible polyurethane foam in the present invention, a foaming agent that can be used for producing an ordinary flexible polyurethane foam can be used without particular limitation. For example, water, halogenated hydrocarbons such as HCFC-141b, HFC-134a, HFC-245fa, HFC-365mfc, low-boiling point aliphatic or alicyclic hydrocarbons such as cyclopentane and n-pentane, liquefied carbon dioxide gas, etc. can give. Among these foaming agents, it is preferable to use liquefied carbon dioxide and water together, and it is particularly preferable to use water alone. These compounds may be used alone or in combination of two or more.

  Examples of the reaction catalyst in the present invention include triethylenediamine (TEDA), bis (N, N-dimethylamino-2-ethyl) ether, N, N, N ′, N′-tetramethylhexamethylenediamine, bis (2 Examples include amine catalysts such as (dimethylaminoethyl) ether (toyocat-ET, manufactured by Tosoh Corporation), metal carboxylates such as potassium acetate and potassium octylate, and organometallic compounds such as dibutyltin dilaurate. Among these, the use of an amine catalyst is preferable because it is suitable for the production of a water-foamed flexible polyurethane foam. These reaction catalysts may be used alone or in combination of two or more. When a reaction catalyst is used, the amount of reaction catalyst used is usually 10 parts by weight or less, preferably 0.05 to 1.0 part by weight, based on 100 parts by weight of the polyol component.

  In the production of the flexible polyurethane foam of the present invention, it is also a preferred aspect to use a low molecular weight polyvalent active hydrogen compound as a crosslinking agent as necessary, and it becomes easy to adjust the spring characteristics of the seat cushion pad. . As such low molecular weight polyhydric active hydrogen compounds, polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin, and these polyhydric alcohols are used as initiators. Examples thereof include compounds having a hydroxyl value of 300 to 1000 mg KOH / g obtained by polymerizing ethylene oxide and propylene oxide, and alkanolamines such as monoethanolamine, diethanolamine, triethanolamine and N-methyldiethanolamine. These compounds may be used alone or in combination of two or more. Commercially available products using these compounds are also suitable, such as KL-210 (Mitsui Chemicals), Hard Master 17 (Daiichi Kogyo Seiyaku Co., Ltd.), EL-980 (Asahi Glass Co., Ltd.) and the like. It is done. When using a crosslinking agent, the usage-amount of a crosslinking agent is not specifically limited, It uses suitably.

  The amount of each component used in the flexible polyurethane foam raw material containing the polyol component, polyisocyanate component, foaming agent, catalyst, and foam stabilizer is usually as follows. Needless to say, the amount used can be appropriately changed for adjustment.

  In the present invention, the equivalent ratio of hydroxyl groups of the polyol component (calculated including water when water is used as a blowing agent) and the equivalent ratio of isocyanate groups of the polyisocyanate component (isocyanate index [NCO index]) is 0.85. It is the range of -1.15 (85-115 in the index display), Preferably it is 0.95-1.05, More preferably, it is 1.0 (100 in the index display).

  The amount of water added in the present invention is usually 0.1 to 8 parts by weight, preferably 2 to 4 parts by weight, based on 100 parts by weight of the polyol compound.

  In addition to the above components, the flexible polyurethane foam raw material in the present invention includes, for example, an antioxidant, an ultraviolet absorber, an anti-aging agent, a filler, a flame retardant, a plasticizer, a colorant, an antifungal / antifungal agent. It is also possible to add various additives such as

  Hereinafter, an example of producing a seat cushion pad as a flexible polyurethane foam will be described.

  The flexible polyurethane foam raw material containing the various components is molded into a seat cushion pad in a predetermined mold corresponding to various shapes according to the application to which the seat cushion pad is applied. Usable means can be employed as the molding method. For example, a predetermined amount of a polyol component, a foaming agent, a catalyst, a foam stabilizer and, if necessary, an additive is weighed and preliminarily mixed to obtain a polyol component, and then a polyisocyanate component is polyurethane foamed into this mixture of the polyol component. A flexible polyurethane foam as a seat cushion pad is obtained by injecting a flexible polyurethane foam molding raw material obtained by rapid mixing using a machine or a stirrer into a mold and removing the mold after a predetermined time. .

When the flexible polyurethane foam obtained by the present invention is used as a seat cushion pad, the density of the flexible polyurethane foam is preferably about 40 to 60 kg / cm ^{3 at the} core, and is preferably about 44 to 55 kg / cm ^3. More preferred.

  In this way, a flexible polyurethane foam molded into a predetermined shape, which is a seat cushion pad, is obtained. On the back surface of the seat cushion pad, for example, a resin supporter made of polyurethane, polypropylene, polyethylene, polystyrene or a foam thereof or PP Supporters (reinforcing materials) such as cloth, coarse blanket, and non-woven fabric can be laminated by an integral molding method in which a supporter (reinforcing material) is inserted into a mold in advance during molding or by adhesion after foam molding.

  A seat seat or the like that is actually mounted on a vehicle is used for assembling the vehicle by covering the seat cushion pad of the present invention with an outer layer such as a main skin, a moquette, a tricot, a jersey, and a fabric, and further attaching metal fittings. When the outer layer is coated on the seat cushion pad, it is also preferable to attach one surface fastener member to the seat cushion pad by adhesion or the like.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, the evaluation methods, such as a physical property in an Example etc., are as follows.

[Physical properties of polyurethane foam moldings]
a) OA density (kg / m ³ ): Foam total density (including skin and core) of a polyurethane foam molding. In Examples and the like, it was set to 59 ± 1.5 kg / cm ³ .

b) 25% ILD (Indentation Load Deflection) (kgf / 314 cm ² ): A load when the seat cushion pad is compressed by 25% with a pressure plate having a diameter of 200 mm (conforms to JIS K 6400). This value is preferably about 20 (kgf / 314 cm ² ) in terms of sitting comfort. In Examples and the like, the pressure was adjusted to 20 ± 2 kgf / 314 cm ² .

  c) Hysteresis loss (%): A measurement sample having a length of 100 mm, a width of 100 mm, and a thickness of at least 30 mm was taken from the core (excluding the skin layer) of the seat cushion pad and measured according to JIS K 6400. The removed skin layer is about 10 mm.

  d) Rebound resilience (%): Measured according to the method defined in JIS K 6400. The number of test pieces was three.

[Vibration transfer characteristics of polyurethane foam moldings]
A sample of 400 × 400 × 100 mm was prepared and post-cured under conditions of 60 ° C. × 6 minutes was used as an evaluation sample.

  Based on JASO B-407, a resonance in the frequency range of 1 to 10 Hz is obtained from a vibration transmissibility curve obtained by applying a forced vibration test with an amplitude of ± 2.5 mm by loading a 50 kg iron-steel pressure plate. The frequency (Hz) and the resonance magnification were measured. For measurement of the vibration characteristics, a seat cushion vibration tester C-1002DL (manufactured by Ito Seiki Co., Ltd.) was used.

[Production of polyurethane foam moldings]
The contents and suppliers of the polyurethane foam raw materials used in the production of the molded polyurethane foam are as follows.

a) Polyether polyol: EP3028, hydroxyl value = 28 ± 2 (mgKOH / g) (Mitsui Takeda Chemical Co., Ltd.)
b) Polymer polyol: POP3128, hydroxyl value = 27.5 ± 1.5 (mgKOH / g) (Mitsui Takeda Chemical Co., Ltd.)
c) Crosslinking agent: DEA, diethanolamine (Mitsui Takeda Chemical Co., Ltd.)
d) Foam stabilizer: SF2962 (manufactured by Toray Dow Corning Silicone), polyoxy (ethylene-propylene) copolymer of polydimethylsiloxane e) Catalyst: TEDA-L33, 33% triethylenediamine solution (manufactured by Tosoh Corporation)
f) Catalyst: toyocat-ET: bis (2-dimethylaminoethyl) ether (manufactured by Tosoh Corporation)
g) Isocyanate: c-MDI: Crude MDI Sumijour 44V (manufactured by Sumitomo Bayer Urethane Co., Ltd.)
h) Isocyanate: TDI-80: Toluene diisocyanate (Mitsui Takeda Chemical Co., Ltd.)
i) Foam stabilizer: KF96L (0.65): main component hexamethyldisiloxane, Me ₃ SiOSiMe ₃ (manufactured by Shin-Etsu Chemical Co., Ltd.)
j) Foam stabilizer: KF96L (1.0): main component octamethyltrisiloxane, Me ₃ Si (OSiMe ₂ ) OSiMe ₃ (manufactured by Shin-Etsu Chemical Co., Ltd.)

（実施例、比較例）
実施例１〜３及び比較例１〜２の軟質ポリウレタンフォーム成型体の原料配合、及び配合量を表１の上段に示した。これらのポリオール成分、架橋剤、整泡剤、触媒、イソシアネート成分、及び発泡剤の各成分を同表に記載の重量比率で常法にて配合し、均一に混合した後、所定量を所定形状の金型に注入し、発泡硬化させて軟質ポリウレタンフォーム成型体を得た。

(Examples and comparative examples)
The raw material blends and blending amounts of the flexible polyurethane foam molded bodies of Examples 1 to 3 and Comparative Examples 1 to 2 are shown in the upper part of Table 1. These polyol components, crosslinking agents, foam stabilizers, catalysts, isocyanate components, and foaming agents are blended in a conventional manner at the weight ratios shown in the same table, and uniformly mixed, and then a predetermined amount of a predetermined shape is formed. The product was poured into a mold and foamed and cured to obtain a flexible polyurethane foam molded product.

  The evaluation results of the molded flexible polyurethane foam are shown in the lower part of Table 1. From these results, in any of Examples 1 to 3 in which hexamethyldisiloxane shown in the present invention was used as a foaming agent, a flexible polyurethane having a high hysteresis loss of 25% or more and a reduced resonance magnification A foam was obtained. On the other hand, in Comparative Example 1 in which octamethyldimethylsiloxane was added instead of hexamethyldisiloxane, and in Comparative Example 2 in which no polydimethylsiloxane compound was added, a soft material having both a high hysteresis loss and a reduction in resonance magnification. A polyurethane foam could not be obtained. Furthermore, in any of these examples, the resonance peak position could be maintained at the same level without greatly changing the hardness and the rebound resilience.

From the above, the flexible polyurethane foam molded body of the present invention has a high teresis loss while maintaining the resonance peak position at the same level as compared with the flexible polyurethane foam molded body having the same degree of hardness and the same degree of rebound resilience. It was confirmed that the resonance magnification at 2 to 4 Hz was reduced. Furthermore, the flexible polyurethane foam formed body of the present invention not only reduces occupant sickness and fatigue when used as a seat cushion pad, but also reduces the sense of swinging up and down (so-called leopard sensation). It can be seen that this improves safety during driving operation.

Claims (4)

  In the method for producing a flexible polyurethane foam, a polyol component containing at least a polyol compound, a reaction catalyst, and a foam stabilizer and an isocyanate component are mixed and foamed and cured using a foaming agent to form a polyurethane foam. A process for producing a flexible polyurethane foam, comprising methyldisiloxane.   The production method according to claim 1, wherein the amount of the hexamethyldisiloxane added is 0.01 to 10 parts by weight with respect to 100 parts by weight of the polyol compound.   The production method according to claim 1 or 2, wherein the isocyanate component contains 10 to 100% by weight of diphenylmethane diisocyanate in all monomer components of the isocyanate component. The flexible polyurethane foam manufactured by the method in any one of Claims 1-3.