JP4548220B2 - Flexible polyurethane foam, method for producing the same, and automotive seat using the flexible polyurethane foam - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a novel flexible polyurethane foam suitable for use in a urethane cushion material having a good ride comfort, particularly an automobile seat.

  In recent years, in the field of polyurethane foams used for various applications, various research and developments have been made to improve the properties suitable for each application. For example, in order to improve the ride comfort of a seat cushion with the upgrading of automobile seats, improvements in resilience, vibration characteristics, durability, and the like have been targeted. Regarding the vibration characteristics, the influence of the vehicle body vibration on the human body is not uniform depending on the vibration frequency, but particularly the attenuation in the frequency range (for example, 4 to 8 Hz or 6 to 20 Hz) that is particularly sensitive to humans is taken. This is said to be effective in improving ride comfort. Further, in order to improve these characteristics, it is considered that a seat cushion using a high molecular weight polyoxyalkylene polyol is more effective than conventionally produced.

  On the other hand, a combination of a pad material made of a metal spring and a flexible polyurethane foam (hereinafter referred to as a flexible foam) has been widely used as a seat cushion. However, in recent years, there has been a tendency to adopt a so-called full-foam type automobile seat in which a metal spring is abolished by giving the flexible foam itself spring characteristics due to demands for cost reduction and weight reduction. The full-form type sheet is thick because it does not use a metal spring.

  In addition, the characteristics of the flexible foam have become a major factor in seat comfort and ride comfort. In other words, static and dynamic characteristics, which are indicators of sitting comfort and riding comfort, have come to be regarded as important in the development of flexible foam. In particular, among static characteristics, it is important to control the feeling of support at the beginning of sitting and the feeling of bottoming at the end of sitting.

  When a person actually sits on a sheet provided with a pad material of soft foam, the flexible foam is compressed and bent, and the position of the buttocks sinks to a specific height. As a measuring method of this static characteristic (static seating feeling), in the load test based on the performance test method of the pad material of the automobile seat of JASO automotive standard B408-89 (1989 edition), the amount of deflection is measured, Deflection when a test method for obtaining a load-deflection curve or a load of 500 N (Newton load) obtained from a load-deflection curve obtained by measurement using a pressure plate according to JIS E7104 (2002 edition) A value may be used. This pressure plate has an oval shape with a major axis A of 300 mm, a minor axis B of 250 mm, and a thickness C of 35 mm or more, and is referred to as a so-called Tekken type.

  On the other hand, polyoxyalkylene polyols generally used as a raw material for flexible foams are alkylene / polypropylene oxides using sodium / potassium-based catalysts such as sodium hydroxide and potassium hydroxide, and initiators such as polyhydric alcohols. It is produced by ring-opening polymerization of oxide. In this production method, an unsaturated monool having an unsaturated bond (hereinafter simply referred to as monool) is produced as a by-product, and this monool is produced by increasing the molecular weight of polyoxyalkylene polyol (decreasing the hydroxyl value). ).

  In a polyoxyalkylene polyol having a hydroxyl value of about 56 mgKOH / g, which is widely used as a raw material for elastic polyurethane foam, the amount of monool produced is not so great as to be a big problem. However, in the case of a polyoxyalkylene polyol having a high molecular weight and a low hydroxyl value, the amount of monool produced becomes a problem. This is because, when an elastic polyurethane foam is produced using a polyoxyalkylene polyol having a high monool content (high total unsaturation), the hardness of the produced foam is reduced, the compression set is reduced, and the foam is produced. This is because a problem such as a decrease in curing property occurs. Furthermore, even if an attempt is made to produce a polyoxyalkylene polyol having a low hydroxyl value using a sodium / potassium-based catalyst, the amount of monool produced is significantly increased, which is practically difficult.

  Therefore, a method for producing an elastic polyurethane foam using a polyoxyalkylene polyol having a low monool content has been proposed for use in automobile seats in order to improve characteristics such as ride comfort and durability (Patent Document 1). reference).

  However, elastic polyurethane foams typified by full-foam types produced using polyoxyalkylene polyols with a low monool content have extremely high rebound resilience (core rebound resilience of 71 to 74%). It has been found that the ride comfort is insufficient from the standpoint of posture maintenance and support of the passengers inside. In order to solve these problems, an invention has been proposed in which a polyoxyalkylene polyol having a low degree of unsaturation and a low molecular weight polyoxyalkylene polyol having a hydroxyl value of 90 to 300 mgKOH / g are used in combination to suppress the impact resilience. However (see Patent Document 2), the value of hysteresis loss is relatively large as 25 to 33%, which is disadvantageous from the viewpoint of durability.

  Further, in the above-mentioned full foam type structure sheet, the load deflection characteristic is greatly influenced by the flexible foam itself. Therefore, when the amount of load deflection when the pressure plate is pressed from above is measured, the pressure side 500N to 900N is measured. The sheet has a relatively small deflection difference. Seats with a small difference in deflection have a feeling of bottoming, and the evaluation of ride comfort tends to be poor. For this reason, full-form sheets have been dealt with by increasing the thickness of the foam in order to increase the deflection difference. As a technique for increasing this difference in deflection without increasing the thickness of the foam, the use of a fluorosurfactant having a perfluoroalkyl group structure has been proposed (Patent Document 3). However, a problem has been pointed out that the effect differs depending on the structure of the fluorosurfactant.

  On the other hand, in a method for producing a polyurethane foam by reacting a polyol component composed of a polyol, a catalyst, a foaming agent and other additives with a polyisocyanate component, by adding a specific bifunctional secondary amine, A method has been proposed in which the slope of the pressure side curve at 75% deflection, which is an index for evaluating the feeling, is reduced, there is no bottoming feeling, and a foam having a good balance of softness, sinking and vibration characteristics is proposed. . However, the feeling of support was insufficient, and durability, particularly wet heat compression set, was insufficient (see Patent Document 4).

  Furthermore, a technique for increasing the surface skin layer density of a foam using a fluorine-based compound is known (Patent Document 5). This technique is a technique particularly applied to the integral skin foam, and is greatly different from the contents of the present invention. In addition, a technology using polytetrafluoroethylene as a pore-opening agent in a cellular polymer including a porous cellular window has been proposed, but this technology is applied to rigid polyurethane foam and is different from the content of the present invention. (Patent Document 6).

JP-A-7-330843 Japanese Patent Laid-Open No. 11-60676 JP-A-11-322875 JP-A-5-320304 JP-A-6-87945 JP-T 8-503720

  The present invention provides a novel flexible polyurethane foam having good vibration characteristics and excellent occupant posture retention.

  The present invention is the following invention which attempts to solve the above-mentioned problems.

A polymer, a polyoxyalkylene polyol having a molecular weight per hydroxyl group of 1000 to 5000, or a polymer-dispersed polyol containing polymer fine particles in the polymer polyoxyalkylene polyol, and a polyisocyanate compound, a catalyst, a foaming agent, and a foam stabilizer In the flexible polyurethane foam obtained by reacting in the presence, 0.01 to 5 parts by mass of polytetrafluoroethylene having an average particle size of 0.1 to 20 μm is used with respect to 100 parts by mass of all active hydrogen compounds. Flexible polyurethane foam.

  An automotive seat comprising the above flexible polyurethane foam.

A polymer, a polyoxyalkylene polyol having a molecular weight per hydroxyl group of 1000 to 5000, or a polymer-dispersed polyol containing polymer fine particles in the polymer polyoxyalkylene polyol, and a polyisocyanate compound, a catalyst, a foaming agent, and a foam stabilizer In the method for producing a flexible polyurethane foam to be reacted in the presence, 0.01 to 5 parts by mass of polytetrafluoroethylene having an average particle size of 0.1 to 20 μm is used with respect to 100 parts by mass of all active hydrogen compounds. A method for producing a flexible polyurethane foam.

  In the present invention, by using a specific polytetrafluoroethylene, a novel flexible polyurethane foam having good vibration characteristics and excellent occupant posture retention is provided.

(Polymer polyoxyalkylene polyol)
The polymer polyoxyalkylene polyol used in the production of the flexible polyurethane foam of the present invention is obtained by ring-opening polymerization of a cyclic ether in the presence of a polymerization catalyst using an active hydrogen compound having an average hydroxyl number of 2 to 6 as an initiator. Those are preferred. The molecular weight per hydroxyl group is preferably 500 or more, particularly preferably 1000 to 5000. The molecular weight per hydroxyl group is particularly preferably 1500 to 2500.

  The polymer polyoxyalkylene polyol average hydroxyl group number is the average hydroxyl group number of the initiator used. The high molecular weight polyoxyalkylene polyol has a molecular weight converted from the hydroxyl value measured according to JIS K-1557 (1970 edition) using the following formula.

    Molecular weight = (56100 × average number of hydroxyl groups of polyol) / hydroxyl value

  Examples of the polymerization catalyst include potassium compounds such as potassium hydroxide and potassium methoxide, alkali metal compounds such as cesium compounds such as cesium metal, cesium hydroxide, cesium carbonate and cesium methoxide, alkali metal hydroxides, boron trifluoride, and the like. Examples thereof include cationic polymerization catalysts such as rides, double metal cyanide complexes, and phosphazenium compounds. Among the above catalysts, a normal alkali catalyst such as potassium hydroxide, a cesium compound, and a double metal cyanide complex are preferable. In order to obtain a polymer having a large molecular weight, it is particularly preferable to use a double metal cyanide complex.

  The cyclic ether is preferably an alkylene oxide having 2 or more carbon atoms, and specific examples include ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide and the like. The combined use of ethylene oxide with at least one selected from propylene oxide, 1,2-butylene oxide, and 2,3-butylene oxide is particularly preferable.

  The polymer polyoxyalkylene polyol preferably has an oxyethylene group, and particularly preferably has an oxyethylene group at the terminal. Moreover, the polyoxyalkylene polyol which has an oxyethylene group inside may be sufficient. The polyoxyalkylene polyol having an oxyethylene group therein can be obtained, for example, by ring-opening polymerization by sequentially or mixing an alkylene oxide having 3 or more carbon atoms and ethylene oxide in an initiator.

  The polyoxyalkylene polyol having an oxyethylene group at the terminal is obtained, for example, by ring-opening polymerization of an alkylene oxide having 3 or more carbon atoms as an initiator and then ring-opening polymerization of ethylene oxide. Further, it is obtained by ring-opening polymerization after sequentially or mixing an alkylene oxide and ethylene oxide having 3 or more carbon atoms with the initiator described above, and then by ring-opening polymerization of ethylene oxide.

  The lower limit of the terminal oxyethylene group content in the polyoxyalkylene polyol is preferably 3% by mass, and particularly preferably 5% by mass. The upper limit is preferably 25% by mass. If the content of the terminal oxyethylene group is less than 3% by mass, foam collapse or the like tends to occur. On the other hand, if the amount exceeds 25% by mass, the number of closed cells in the foam increases, and the foam is cracked during the crushing process or shrinkage after the crushing process occurs.

  The total oxyethylene group content is preferably 30% by mass or less.

  As initiators, ethylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, dextrose, sucrose, bisphenol A or the like, or a compound obtained by adding a small amount of alkylene oxide to them is used, and one or more of these are preferably used in combination. When the average number of hydroxyl groups is less than 2, the durability and riding comfort of the foam may be lowered. On the other hand, if the average number of hydroxyl groups is larger than 6, the produced flexible foam tends to be hard and mechanical properties such as elongation tend to be deteriorated.

  In the present invention, it is preferable to use the polyoxyalkylene polyol (a) as at least a part of the polymer polyoxyalkylene polyol. The polyoxyalkylene polyol (a) is a polyoxyalkylene polyol having a degree of unsaturation of 0.07 meq / g or less among the high-molecular polyoxyalkylene polyols (hereinafter also referred to as polyol (a)). In particular, 30 to 100% by mass of the polymer polyoxyalkylene polyol is preferably the polyol (a), and particularly preferably 40 to 100% by mass. In the case where the polymer polyoxyalkylene polyol contains polymer fine particles as described later, the ratio of the polymer polyoxyalkylene polyol and polyol (a) is calculated based on the mass of the polyol excluding the polymer fine particles.

  The average molecular weight per hydroxyl group of the polyol (a) is preferably 500 or more, more preferably 1000 to 5000, and particularly preferably 1500 to 2500. When the average molecular weight per hydroxyl group is smaller than 1500, the durability and ride comfort of the polyurethane foam may be lowered. On the other hand, when it is larger than 2500, the viscosity of the polyol is increased and workability is lowered.

  The polyol (a) preferably contains an oxyethylene group at the terminal, and the preferred range is as described for the polymer polyoxyalkylene polyol. The polyol (a) is preferably a polyol having an oxypropylene group content of 70% by mass or more, and particularly preferably 75% by mass or more.

  The polyol (a) has an unsaturation degree of 0.07 meq / g or less, particularly preferably 0.05 meq / g or less. When the degree of unsaturation of the polyol (a) is greater than 0.07 meq / g, the durability and ride comfort of the polyurethane foam may be lowered.

  In the present invention, a polymer-dispersed polyol containing polymer fine particles in a polymer polyoxyalkylene polyol may be used. The polymer-dispersed polyol contains fine polymer particles in a polyoxyalkylene polyol matrix, and the fine polymer particles are preferably dispersed and contained. As the polymer fine particles, addition polymerization polymers and condensation polymerization polymers are preferable.

  Examples of the addition polymerization polymer include homopolymers and copolymers of vinyl monomers such as acrylonitrile, styrene, methacrylic acid ester, and acrylic acid ester. Examples of the polycondensation polymer include polyester, polyurea, polyurethane, and melamine resin. Due to the presence of these polymer fine particles, the hydroxyl value of the whole polymer-dispersed polyol is generally lowered from the hydroxyl value of the matrix polyol.

  The content of the polymer fine particles contained in the polymer polyoxyalkylene polyol is preferably 50% by mass or less. If the content of the polymer fine particles is more than 50% by mass, the viscosity becomes high, which may be inconvenient. The polymer fine particles are preferably contained in the polymer polyoxyalkylene polyol in an amount of 1 to 35% by mass.

(Polytetrafluoroethylene)
In the present invention, polytetrafluoroethylene having an average particle size of 0.1 to 20 μm is used. About an average particle diameter, it can obtain | require by the 50% average particle diameter by a general laser diffraction method. When the average particle size is larger than 20 μm, the above-mentioned flexible foam cannot be sufficiently satisfied, which is not preferable. Further, even when the average particle size is less than 0.1 μm, it is not preferable because the above-mentioned flexible properties cannot be sufficiently satisfied.

  The usage-amount of polytetrafluoroethylene is 0.01-5 mass parts with respect to a total of 100 mass parts of all the active hydrogen compounds. When the amount is less than 0.01 parts by mass, the above-mentioned flexible foam characteristics are not exhibited, which is not preferable. Moreover, when using more than 5 mass parts, the foam stability at the time of foaming is impaired and it is unpreferable. The all active hydrogen compound means a compound containing an active hydrogen atom that can react with an isocyanate group, such as a polymer polyoxyalkylene polyol, a crosslinking agent, and water. It is preferable that the usage-amount of polytetrafluoroethylene is 0.01-1 mass part with respect to a total of 100 mass parts of all the active hydrogen compounds.

(Foam stabilizer)
In the present invention, a foam stabilizer is used. As the foam stabilizer, it is preferable to use a silicone compound. As the silicone compound, a silicone foam stabilizer usually used for flexible urethane foam can be used. As for the usage-amount of a silicone type foam stabilizer, 0.001-3 mass parts is preferable with respect to a total of 100 mass parts of all the active hydrogen compounds.

(Polyisocyanate)
The polyisocyanate compound used for producing the polyurethane foam of the present invention is preferably an aromatic polyisocyanate, and examples include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and polymethylene polyphenyl polyisocyanate (crude MDI). These may be a mixture, and a mixture of 85/15 to 75/25 (mass ratio) of a mixture of TDI and crude MDI is particularly preferable.

  The amount of the polyisocyanate compound used is a value represented by 100 times the number of isocyanate groups relative to the total number of active hydrogens such as polyoxyalkylene polyol and water (usually this number is referred to as isocyanate index), preferably 80 to 120, especially Preferably it is 85-115.

(Foaming agent)
As the foaming agent in the present invention, one or more foaming agents selected from water and inert gas are preferably used. Examples of the inert gas include air, nitrogen, carbon dioxide and the like. It is preferred to use only water. The usage-amount of these foaming agents is not specifically limited, When only water is used, 10 mass parts or less are preferable with respect to 100 mass parts of high molecular polyoxyalkylene polyols, and 0.1-8 mass parts is especially preferable. Other foaming agents can be used in an appropriate amount according to demands such as foaming ratio.

(Foam breaker)
In the present invention, a foam breaker may be used. As the foam breaker, a polyol having an average number of hydroxyl groups of 2 to 8, a hydroxyl value of 20 to 100 mgKOH / g, and an oxyethylene group content of 50 to 100% by mass is preferable. The amount of the foam breaker used is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the high molecular weight polyoxyalkylene polyol.

(Crosslinking agent)
In the present invention, a crosslinking agent may be used. As the crosslinking agent, a polyol having an average number of hydroxyl groups of 2 to 8 and a hydroxyl value of 200 to 2000 mgKOH / g is preferable. 0.1-10 mass parts is preferable with respect to 100 mass parts of high molecular weight polyoxyalkylene polyol, and, as for the usage-amount of a crosslinking agent, 0.5-10 mass parts is preferable.

(catalyst)
As a catalyst in this invention, the catalyst which accelerates | stimulates a urethanation reaction can be used. For example, tertiary amines such as triethylenediamine, bis [(2-dimethylamino) ethyl] ether, N, N, N ′, N′-tetramethylhexamethylenediamine, potassium acetate, potassium 2-ethylhexanoate, etc. Examples thereof include organic metal compounds such as carboxylic acid metal salts, dibutyltin dilaurate, and stannous octoate.

(Other)
In the present invention, known additives such as emulsifiers, antioxidants, anti-aging agents such as ultraviolet absorbers, fillers such as calcium carbonate and barium sulfate, flame retardants, plasticizers, colorants, anti-fungal agents, Auxiliaries can be used as needed.

(Production method)
Production and molding of flexible polyurethane foam is a method in which a reactive mixture is directly injected into a mold using a low-pressure foaming machine or a high-pressure foaming machine (that is, a reaction injection molding method), or a reactive mixture is injected into an open mold. It is preferable to carry out by the method to do. The high-pressure foaming machine is preferably a type in which two ordinary liquids are mixed, one of which is a polyisocyanate compound, and the other liquid is a mixture of all raw materials other than the polyisocyanate compound. In some cases, a reactive mixture can be formed and injected with a total of three components including a catalyst, a foam breaker (usually used by being dispersed or dissolved in a part of the high molecular weight polyoxyalkylene polyol), and the like. The flexible polyurethane foam of the present invention is usually produced by a cold cure method, but can be produced by a method other than the cold cure method, for example, a method including a heating step.

(Physical properties of flexible foam)
The core density of the flexible polyurethane foam of the present invention is preferably ³⁰ to 70 kg / m ³ , and the core density of 35 to 60 kg / m ³ is particularly preferable in order to adapt to an automobile seat cushion. When the core density is less than 30 kg / m ³ , durability and ride comfort performance deteriorate. Further, when the core density exceeds 70 kg / m ³ , durability and ride comfort are good, but when considering application to an automobile seat, it is not preferable because it hinders improvement in fuel consumption.

The hardness of the flexible polyurethane foam of the present invention is such that a foam obtained by foaming to a thickness of 100 mm has a 25% hardness (ILD) measured according to JIS K-6400 (1997 edition) of 180 to 500 N / 314 cm ² is preferable, and 180 to 350 N / 314 cm ² is more preferable. When it is lower than 180 N / 314 cm ² , the support feeling of the passenger is impaired, which is not preferable. On the other hand, if it exceeds 500 N / 314 cm ² , the sheet is less flexible and the ride quality is lowered.

The flexible polyurethane foam of the present invention has a 25% hardness (ILD) measured in accordance with JIS K6400 (1997 edition), X, JIS E7104 (2002 edition), for a foam obtained by foaming to a thickness of 100 mm. The deflection value on the 500N pressure side is subtracted from the deflection value on the 900N pressure side obtained from the load-deflection curve obtained by applying a load at a constant speed of 10 mm / s or less using a compliant pressure plate (Ikenken type). It is preferable that the value (pressure side deflection difference) Y (mm) satisfies the relational expression represented by the expression (1).
Y ≧ −0.000370842X ² + 0.225401X-10.5013 (1)
By satisfying the range of the above relational expression, a sufficient amount of deflection as a sheet can be ensured.

  The flexible polyurethane foam of the present invention is a foam obtained by foaming to a thickness of 100 mm, using a pressure plate (Iken type) conforming to JIS E7104 (2002 edition), at a constant speed of 10 mm / s or less. The value obtained by subtracting the deflection value on the 500N pressurization side from the deflection value on the 900N pressurization side when the deflection value on the 500N pressurization side obtained from the load-deflection curve measured by applying a load in step 5 is 5.0 to 55.0 mm. (Pressure-side deflection difference) Y (mm) is preferably 22.5 to 33.0 mm. It is especially preferable that it is 23.0-33.0 mm.

  When the deflection value on the 500N pressure side is 5.0 to 55.0 mm, the value obtained by subtracting the deflection value on the 500N pressure side from the deflection value on the 900N pressure side (foam side deflection difference) Y (mm) at a foam thickness of 100 mm is 22. When the thickness is less than 5 mm, a feeling of bottoming of the sheet slightly occurs, which is not preferable. Further, when the pressure side deflection difference (mm) Y exceeds 33.0 mm, the posture retention is deteriorated, which is not preferable.

  The flexible polyurethane foam of the present invention is a foam obtained by further foaming to a thickness of 100 mm, using a pressure plate (Iken type) conforming to JIS E7104 (2002 edition), at a constant speed of 10 mm / s or less. The value obtained by subtracting the deflection value on the 500N pressurization side from the deflection value on the 900N pressurization side when the deflection value on the 500N pressurization side obtained from the load-deflection curve measured by applying a load at 15.0 to 55.0 mm (Pressure-side deflection difference) Y (mm) is more preferably 22.5 to 33.0 mm, and more preferably 23.0 to 33.0 mm.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

  Tables 1 and 2 show the blending (unit: parts by mass) at the time of foam production and the foam physical properties, vibration characteristics and moldability of the obtained flexible polyurethane foam. Examples 1 to 3 are examples, and example 4 is a comparative example.

  Further, the measurement of the degree of unsaturation was carried out by a method based on JIS K 1557 (1970 edition).

  Among the raw materials shown in Tables 1 and 2, the mixture of all raw materials other than the polyisocyanate compound (polyol-containing mixture) was adjusted to 30 ° C. ± 1 ° C., and the isocyanate compound was adjusted to 25 ° C. ± 1 ° C. Polytetrafluoroethylene was mixed after being uniformly dispersed in a polyol. Thereafter, a polyisocyanate compound was added to the polyol-containing mixture so as to have an isocyanate index as shown in Tables 1 and 2, and stirred and mixed for 5 seconds with a high-speed mixer (2500 rpm), and immediately heated to 60 ° C., 400 mm in length and width. It was poured into a mold having an inner dimension of 100 mm in height and sealed. After curing for 6 minutes, the flexible polyurethane foam was taken out and allowed to stand for 24 hours or more, and various physical properties were measured.

(Form physical properties)
Foam physical properties are: total density (unit: kg / m ³ ), core density (unit: kg / m ³ ), 25% hardness (ILD) (unit: N / 314 cm ² ), core resilience modulus (Unit:%), tear strength (unit: N / cm), tensile strength (unit: kPa), elongation (unit:%), dry heat compression set (Dry Set) (unit:%), wet heat compression permanent Strain (Wet Set) (unit:%) and hysteresis loss (unit:%) were evaluated.

  The density of the core part and the rebound resilience of the core part were measured using a sample cut into dimensions of 100 mm in length and width and 50 mm in height excluding the skin part from the center of the foam.

  The total density, core density, 25% hardness (ILD), core rebound resilience, tear strength, tensile strength, elongation, dry heat compression set, wet heat compression set, and hysteresis loss are JIS K6400 ( 1997 version). Hysteresis loss was measured using a pressure plate (Iken type) conforming to JIS E7104 (2002 edition).

  A test method for obtaining a load-deflection curve is as follows: 1. Using a pressure plate having an oval shape having a major axis A of 300 mm, a minor axis B of 250 mm, and a thickness C of 35 mm or more in accordance with JIS E7104 (2002 edition). Measurement was performed by applying a load at a constant speed of 7 mm / s. The deflection value (mm) when a 500 N load (Newton load) was applied was obtained from the load-deflection curve. A pressure-side deflection difference Y (mm) was obtained from the pressure-side deflection value (mm) at a load of 900 N and the pressure-side deflection value at a load of 500 N (the value obtained by subtracting the latter from the former was defined as Y).

25% hardness (ILD) was set to X, and the value of y was calculated from the following formula (2).
y = −0.000370842X ² + 0.225401X-10.5013 (2)

(Vibration characteristics)
For the vibration characteristics, the resonance frequency (unit: Hz), resonance magnification (absolute displacement measurement), and 6 Hz transmission rate were evaluated. The resonance frequency, resonance magnification (absolute displacement measurement), and 6 Hz transmission rate (absolute displacement measurement) were measured by a method based on JASO B407-87. As vibration characteristic measurement conditions, a steel plate type (load: 490 N) was used as a pressure plate, and the total vibration amplitude was set to 5 mm.

(Formability)
As for moldability, crushing property was evaluated. The crushing property is an evaluation of foam communication. That is, the load required when the obtained flexible polyurethane foam was made to pass through a roller and a foam cell was connected was evaluated. The lower the foaming rate of the foam, that is, the better the communication, the smaller the required load.

(Raw material)
Polyol a1: Poly having an average number of hydroxyl groups of 3, hydroxyl value of 24 mg KOH / g (molecular weight per hydroxyl group of 2340), unsaturation of 0.04 meq / g, and containing 16% by mass of polyoxyethylene groups at the ends Oxypropyleneoxyethylene polyol.
Polyol b1: A polymer-dispersed polyol obtained by polymerizing acrylonitrile in polyol a1 and having a fine polymer content of 22% by mass.
Foam breaker c1: Polyoxypropylene oxyethylene polyol having an average number of hydroxyl groups of 3, a hydroxyl value of 48 mg KOH / g (molecular weight per hydroxyl group of 1170), and an oxyethylene group content of 80% by mass.
Crosslinking agent d1: diethanolamine.
Crosslinking agent d2: polyoxyethylene polyol having an average number of hydroxyl groups of 4 and a hydroxyl value of 562 mg KOH / g (molecular weight per hydroxyl group is 100).
Catalyst e1: Dipropylene glycol solution of triethylenediamine. Product name: TEDA-L33 manufactured by Tosoh Corporation.
Catalyst e2: Dipropylene glycol solution of bis-[(2-dimethylamino) ethyl] ether. Product name: TOYOCAT-ET manufactured by Tosoh Corporation.
Catalyst e3: amine catalyst, trade name: TOYOCAT-NCT manufactured by Tosoh Corporation.
Silicone type foam stabilizer f1: Trade name: SZ-1313 manufactured by Toray Dow Corning.
Polytetrafluoroethylene g1: Average particle diameter of 8.5 μm (powder).
Polytetrafluoroethylene g2: Average particle size of 4.0 μm (powder).
Blowing agent h: water polyisocyanate j: TDI (mixture of 2,4-tolylene diisocyanate / 2,6-tolylene diisocyanate 80/20% by mass) and polymethylene polyphenyl polyisocyanate 80/20% by mass, The NCO group content is 44.8%. Product name: Coronate 1021 manufactured by Nippon Polyurethane Industry Co., Ltd.

  As shown in Tables 1 and 2, the flexible urethane foam of the present invention uses a specific polytetrafluoroethylene to increase the 900N-500N pressure side deflection difference in the foam foamed to a thickness of 100 mm. A foam with little bottoming can be obtained. All of the contents shown in these examples are particularly excellent in vibration characteristics, particularly resonance magnification, and a transmission rate of 6 Hz, and the riding comfort is good.

The flexible polyurethane foam of the present invention is used for cushions, seats and the like. Particularly, it is suitable as a vehicle seat, and among them, it is suitable as an automobile seat.

Claims (8)

A polymer-dispersed polyol containing fine polymer particles molecular weight per hydroxyl group in the polymer polyoxyalkylene polyol or the polymeric polyoxyalkylene polyol 1000-5000, a polyisocyanate compound, a catalyst, a blowing agent, and foam stabilizer In the flexible polyurethane foam obtained by reacting in the presence, 0.01 to 5 parts by mass of polytetrafluoroethylene having an average particle size of 0.1 to 20 μm is used with respect to 100 parts by mass of all active hydrogen compounds. Flexible polyurethane foam. The flexible polyurethane foam according to claim 1, wherein the density of the core part is 30 to 70 kg / m ³ . The flexible polyurethane foam according to claim 2, wherein the density of the core part is 35 to 60 kg / m ³ . For foams obtained by foaming to a thickness of 100 mm, the deflection value on the pressure side of 500 N obtained from a load-deflection curve measured using a pressure plate (Iken type) conforming to JIS E7104 (2002 edition) is The value obtained by subtracting the deflection value on the pressure side of 500N from the deflection value on the pressure side of 900N when the value is 5.0 to 55.0 mm (pressure side deflection difference) Y (mm) is 22.5 to 33.0 mm. The flexible polyurethane foam as described in any one of 1-3 . For foams obtained by foaming to a thickness of 100 mm, the deflection value on the pressure side of 500 N obtained from a load-deflection curve measured using a pressure plate (Iken type) conforming to JIS E7104 (2002 edition) is When 18.0 to 55.0 mm, a value obtained by subtracting a deflection value on the pressure side of 500N from a deflection value on the pressure side of 900N (pressure side deflection difference) Y (mm) is 22.5 to 33.0 mm. The flexible polyurethane foam as described in any one of 1-3 . An automobile sheet comprising the flexible polyurethane foam according to any one of claims 1 to 5 . A polymer-dispersed polyol containing fine polymer particles molecular weight per hydroxyl group in the polymer polyoxyalkylene polyol or the polymeric polyoxyalkylene polyol 1000-5000, a polyisocyanate compound, a catalyst, a blowing agent, and foam stabilizer In the method for producing a flexible polyurethane foam to be reacted in the presence, 0.01 to 5 parts by mass of polytetrafluoroethylene having an average particle size of 0.1 to 20 μm is used with respect to 100 parts by mass of all active hydrogen compounds. A method for producing a flexible polyurethane foam. The method for producing a flexible polyurethane foam according to claim 7 , wherein at least one selected from water and an inert gas is used as the foaming agent.