Seat pad

Abstract

To improve ride comfort performance of a seat pad by improving at least one of bending, durability, front surface softness, and little bottom touch feeling.SOLUTION: A seat pad is made of polyurethane foam obtained from a composition containing polyol and isocyanate. The seat pad has a compression deflection coefficient of 2.8 or less as measured in accordance with JIS K6400-2 (2012 version) Method E. Further, F1 / F3<1.0 is satisfied when a portion between a front surface and a back surface is divided into five equal parts in a thickness direction, which are defined as a first layer, a second layer, a third layer, a fourth layer, and a fifth layer in this order from the front surface side, F3 refers to an Asker F hardness of the third layer measured from the front surface side, and F1 refers to an Asker F hardness of the first layer measured from the front surface side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a seat pad. This application is based on and claims the benefit of priority from Japanese Patent Application No. 2022-108852 filed on July 6, 2022, and Japanese Patent Application No. 2022-179573 filed on November 9, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Patent Documents 1 and 2 describe seat cushion materials that use polyether polyol (PPG). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-107933 [Patent Document 2] Japanese Patent Publication No. 2022-039004 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for improved ride comfort in seat pads installed in vehicles such as automobiles, ships, and aircraft. Ride comfort performance includes good flexibility and a reduced feeling of bottoming out, durability to maintain the seated occupant's posture, and a soft surface that provides a pleasant feel when seated. However, it has been difficult to sufficiently improve ride comfort with conventional seat pads. The present disclosure has been made in consideration of the above-mentioned situation, and aims to improve the ride comfort performance of a seat pad by improving at least one of good flexibility, reduced feeling of bottoming out, durability, and surface softness. The present disclosure can be realized in the following forms. [Means for solving the problem]

[0005] <First aspect> [1] A seat pad made of polyurethane foam obtained from a composition containing a polyol and an isocyanate, A seat pad with a compression deflection coefficient of 2.8 or less measured in accordance with JIS K6400-2 (2012 edition) Method E.

[0006] <Second mode> [2] A seat pad made of polyurethane foam obtained from a composition containing a polyol and an isocyanate, The polyol includes a polyether polyol having an ethylene oxide unit content of 50 mol % or more when the total amount of alkylene oxide units is taken as 100 mol %, The space between the front and back surfaces is divided into five equal parts in the thickness direction, and the layers are designated as a first layer, a second layer, a third layer, a fourth layer, and a fifth layer in order from the front surface side, The Asker F hardness of the third layer measured from the surface side is designated as F3, When the Asker F hardness measured from the surface side of the first layer is F1, F1 / F3<1.0 Meet the seat pad. [Effects of the Invention]

[0007] The seat pad of the present disclosure can improve ride comfort. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 shows a vehicle seat with a polyurethane foam seat pad. [Figure 2] FIG. 10 is a diagram illustrating the first to fifth layers of the seat pad of the second embodiment. [Figure 3] 1 is a top view of an example of a seat pad according to a first embodiment. FIG. [Figure 4]FIG. 4 is a cross-sectional view taken along line VV in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Here, a preferred example of the present disclosure will be described. [3] The seat pad according to [2], satisfying 0.30≦F1 / F3≦0.70. [4] The seat pad according to [2] or [3], wherein the isocyanate includes carbodiimide-modified diphenylmethane diisocyanate. [5] A seat pad according to any one of [2] to [4], having a compressive deflection coefficient measured in accordance with JIS K6400-2 (2012 edition) E method of 2.8 or less. [6] A seat pad according to any one of [2] to [5], having a resilience of 55% or less as measured in accordance with JIS K6400-3 (2011 edition). [7] A seat pad according to any one of [2] to [6], having a stress relaxation rate of 15% or less. [8] A seat pad according to any one of [2] to [7], wherein the hysteresis loss rate measured in accordance with JIS K6400-2 (2012 edition) E method is 20% or less.

[0010] The present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "-", it is intended to include both the lower limit and the upper limit unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less".

[0011] 1. Seat pad 110 (first embodiment) The seat pad 110 is made of polyurethane foam obtained from a composition containing polyol and isocyanate. The seat pad 110 has a compression deflection coefficient of 2.8 or less as measured in accordance with JIS K6400-2 (2012 edition) Method E.

[0012] (1) Composition The seat pad 110 is made of polyurethane foam, preferably flexible polyurethane foam. The polyurethane foam is obtained from a composition containing a polyol and an isocyanate. The composition may contain at least one component selected from a blowing agent, a catalyst, a foam stabilizer, and a crosslinking agent as an optional component.

[0013] The polyol is not particularly limited. The polyol preferably contains a polyol (a) having an EO unit content of 50 mol% or more when the total amount of alkylene oxide units is 100 mol%. The explanation in the section "Seat Pad 10 (Second Aspect)" below applies to the polyol (a) as is, and the description thereof will be omitted. The explanation in the section "Seat Pad 10 (Second Aspect)" below applies to the components other than the polyol (a) in the composition as well, and the description thereof will be omitted.

[0014] (2) Physical properties of the seat pad 110 (2.1) Compression deflection coefficient The compression deflection coefficient is calculated in accordance with JIS K6400-2 (2012 edition) E method by taking a force-deflection curve and dividing the force at 65% compression by the force at 25% compression. Compression deflection coefficient = force at 65% compression / force at 25% compression

[0015] It is generally said that the smaller the compression deflection coefficient, the more flexible the polyurethane foam. Furthermore, the deflection characteristics in the low load range can be an indicator of the feeling of bottoming out when a person sits on it. The deflection characteristics in the high load range (e.g., 700N or more and 980N or less) can be an indicator of the feeling of bottoming out when vibrations occur during driving, etc. The inventors of the present application have discovered that by setting the compression deflection coefficient of the seat pad to 2.8 or less, it is possible to make it difficult to feel the feeling of bottoming out, mainly in the high load range. In other words, the technology of the present disclosure was developed based on the discovery that by reducing the compression deflection coefficient, it is possible to obtain a seat pad 110 that is flexible and that makes it difficult to feel the feeling of bottoming out.

[0016] The compression deflection coefficient of the seat pad 110 (based on JIS K6400-2 (2012 edition) E method) is 2.8 or less, preferably 2.7 or less, and more preferably 2.5 or less. The lower limit of the compression deflection coefficient of the seat pad 110 is not particularly limited, and may be, for example, 2.0 or more, or 2.2 or more. The test specimen used for measurement is the entire seat pad 110, including the skin. For example, the compression deflection coefficient of the seat pad 110 in Figures 3 and 4 can be measured as follows. A pressure plate 120 is placed on the part of the seat pad that comes into contact with the buttocks, and a force-deflection curve is taken in accordance with JIS K6400-2 (2012 edition) Method E. When taking the force-deflection curve, the load used to return from pressure to pressure during compression of the seat pad is set to 980 N. The force at 65% compression and the force at 25% compression are calculated as follows: The thickness T at the thinnest position P1 located under the pressure plate 120 is min The initial thickness (thickness before compression) is 100%, and the thickness T at the thinnest position P1 min The force when the thickness is compressed by 25% of the original thickness to 75% is defined as the force at 25% compression. The thickness T at the thinnest position P1 min The force when the material is compressed by 65% ​​of its original thickness to 35% of its original thickness is defined as the force at 65% compression. Then, the compression deflection coefficient is calculated based on the above formula. The shape of the seat pad is not limited to the shapes shown in Figs. 3 and 4. For example, the shape of the seat pad may be a rectangular parallelepiped, as in Experimental Example 1-10 described later. In Experimental Examples 1-6, 8-10 described later, a rectangular parallelepiped having a length of 400 mm, a width of 400 mm, and a height of 100 mm including the skin is used as the test piece, so the thickness T min The initial thickness (thickness before compression) of the specimen is 100 mm, the thickness at 25% compression is 75 mm, and the thickness at 65% compression is 35 mm. In Experimental Example 7 described later, a rectangular parallelepiped having a length of 400 mm, a width of 400 mm, and a height of 50 mm including the skin is used as the test specimen, so the thickness T minThe initial thickness (thickness before compression) is 50 mm, the thickness at 25% compression is 37.5 mm, and the thickness at 65% compression is 17.5 mm.

[0017] (2.2) Hysteresis loss rate From the viewpoint of durability, the hysteresis loss rate of the seat pad 110 (based on JIS K6400-2 (2012 edition) E method) is preferably 22% or less, more preferably 20% or less, and may be 18% or less, or 15% or less. The lower limit of the hysteresis loss rate is not particularly limited, but is usually 5.0% or more. The test specimen used for measurement and the method for obtaining the force-deflection curve are the same as those for (2.1) Compression deflection coefficient.

[0018] (2.3) Density The density of the center portion of the seat pad 110, excluding the front and back surfaces, is not particularly limited. From the viewpoint of weight reduction, the density is preferably 100 kg / m 3 More preferably, it is 80 kg / m or less. 3 More preferably, it is 75 kg / m or less. 3 The lower limit of the density is not particularly limited, but is usually 20 kg / m 3 From these viewpoints, the density is preferably 20 kg / m 3 More than 100kg / m 3 The range may be any range that is an appropriate combination of the above lower and upper limits. The density of the central portion excluding the front and back surfaces can be measured as follows. A rectangular parallelepiped test piece 100 mm long, 100 mm wide, and 50 mm high, excluding the skin, is taken from the center of the seat pad 110. The height direction of the test piece is aligned with the front and back directions of the seat pad 110. The mass of the taken test piece is measured, and the mass of the test piece is divided by the volume to determine the density (kg / m) of the center. 3 ) is calculated.

[0019] (2.4) 25% hardness There are no particular limitations on the 25% hardness (based on JIS K6400-2 (2012 edition) Method D) of the seat pad 110. The 25% hardness of the entire seat pad 110 is preferably 80N or more and 400N or less, more preferably 120N or more and 300N or less, and even more preferably 160N or more and 280N or less. The test specimen for hardness measurement is a rectangular parallelepiped measuring 400 mm in length and 400 mm in width, including the front and back skins. For example, in Experimental Examples 1-6, 8-10 described later, the test specimen is a rectangular parallelepiped measuring 400 mm in length, 400 mm in width, and 100 mm in height, including the skins. In Experimental Example 7 described later, the test specimen is a rectangular parallelepiped measuring 400 mm in length, 400 mm in width, and 50 mm in height, including the skins. A pressure plate with a diameter of 200 mm is used for measurement. During measurement, the test specimen is placed on the support plate of the testing machine so that the center of the test specimen is at the center of the pressure plate.

[0020] (2.5) Stress relaxation rate From the viewpoint of durability, the stress relaxation rate of the seat pad 110 is preferably 24% or less, more preferably 20% or less, and even more preferably 15% or less, and may be 12% or less, 10% or less, 9.0% or less, or 8.0% or less. The lower limit of the stress relaxation rate is not particularly limited and may be, for example, 1.0% or more. The smaller the stress relaxation rate, the less sagging of the urethane after sitting and the better the durability. The stress relaxation rate tends to increase as the thickness of the seat pad 110 is reduced. The technology of the present disclosure is particularly useful in that it can reduce the stress relaxation rate even in a thin seat pad 110. The stress relaxation rate (%) can be measured as follows. The test specimen used for measurement is the entire seat pad 110, including the skin. The height direction of the test specimen is aligned with the front-to-back direction of the seat pad 110. A circular pressure plate 120 with a diameter of 200 mm is used to compress the polyurethane foam at a speed of 50 mm / min through a distance of 75% of the initial thickness. The pressure plate 120 is placed on the part of the seat pad 110 that will be in contact with the buttocks. The thickness of the seat pad 110 at the position below the center of the pressure plate 120 is taken as the initial thickness (thickness before compression). The load is then removed and the test is allowed to stand for one minute. A load is again applied at the same speed, and the pressure plate is stopped when a load of 196 N (20 kgf) is reached. The load is then read after five minutes of standing. The stress relaxation rate is then calculated using the following formula: Stress relaxation rate (%) = 100 x [load when pressure plate is stopped (196N) - load after leaving for 5 minutes] / load when pressure plate is stopped (196N) The shape of the seat pad is not limited to the shapes shown in Figs. 3 and 4. For example, the shape of the seat pad may be a rectangular parallelepiped, as in Experimental Examples 1-10 described later. In Experimental Examples 1-6 and 8-10 described later, a rectangular parallelepiped having a length of 400 mm, a width of 400 mm, and a height of 100 mm, including the skin, is used as the test piece, so the thickness at the position below the center of the pressure plate 120, i.e., the initial thickness (thickness before compression), is 100 mm. In Experimental Example 7 described later, a rectangular parallelepiped having a length of 400 mm, a width of 400 mm, and a height of 50 mm, including the skin, is used as the test piece, so the thickness at the position below the center of the pressure plate 120, i.e., the initial thickness (thickness before compression), is 50 mm.

[0021] (2.6) Rebound Resilience From the viewpoint of improving ride comfort, the rebound resilience of the seat pad 110 (based on JIS K6400-3 (2011 edition)) is preferably 70% or less, more preferably 60% or less, even more preferably 55% or less, and may be 50% or less, 46% or less, or 44% or less. The lower limit of the rebound resilience of the seat pad 110 is not particularly limited, and may be, for example, 10% or more, 20% or more, or 30% or more.

[0022] 2. Manufacturing method of seat pad 110 Regarding the seat pad 110, the explanation in the section "2. Manufacturing method of the seat pad 10" described later applies as is, and the description thereof will be omitted.

[0023] 3. Effects of this embodiment In recent years, ensuring ride comfort has become an issue as seat pads 110 for automobiles, ships, aircraft, etc. have become thinner and lighter. Ride comfort performance includes good flexibility and a reduced feeling of bottoming out. The seat pad 110 of this embodiment has a small deflection coefficient, so it deflects well and does not easily feel like it is bottoming out. For example, the seat pad 110 of this embodiment can ensure ride comfort even when a so-called floor slab is not placed, and can contribute to making the seat pad 110 lighter, thinner, and less costly.

[0024] 4. Seat pad 10 (second embodiment) The seat pad 10 is made of polyurethane foam obtained from a composition containing a polyol and an isocyanate. The polyol contains a polyether polyol having an ethylene oxide unit content of 50 mol% or more, where the total amount of alkylene oxide units is 100 mol%. The seat pad 10 is divided into five equal parts in the thickness direction between the front surface 10A and the back surface 10B. The thickness direction of the seat pad 10 is divided into five equal parts, namely, a first layer 11, a second layer 12, a third layer 13, a fourth layer 14, and a fifth layer 15, in order from the front surface 10A side. When the Asker F hardness of the third layer 13 measured from the front surface 10A side is F3 and the Asker F hardness of the first layer 11 measured from the front surface 10A side is F1, the relationship F1 / F3<1.0 is satisfied.

[0025] (1) Composition The seat pad 10 is made of polyurethane foam, preferably flexible polyurethane foam. The polyurethane foam is obtained from a composition containing a polyol and an isocyanate. The composition may contain at least one component selected from a blowing agent, a catalyst, a foam stabilizer, and a crosslinking agent as an optional component. Each component of the composition will be described below.

[0026] (1.1) Polyol The polyol includes polyol (a) having an EO unit content of 50 mol% or more when the total amount of alkylene oxide units is taken as 100 mol%. Hereinafter, the content of EO units refers to the content when the total amount of alkylene oxide units is taken as 100 mol%.

[0027] The polyol (a) is a polyether polyol having an EO unit content of 50 mol% or more. From the viewpoint of reducing the stress relaxation rate and the hysteresis loss rate, the EO unit content is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 75 mol% or more, and particularly preferably 80 mol% or more. The upper limit of the EO unit content is not particularly limited and may be 100 mol%. Only one type of polyol (a) may be used, or two or more types may be used in combination. For example, a polyol having an EO unit content of 75 mol% and a polyol having an EO unit content of 80 mol% may be used in combination. Examples of alkylene oxides other than ethylene oxide that can be used in the production of polyol (a) include propylene oxide and butylene oxide. As the alkylene oxide other than ethylene oxide, propylene oxide is preferred. As polyol (a), a polyol whose entire content, other than EO units, is propylene oxide units (hereinafter abbreviated as "PO units") can be preferably used.

[0028] The number average molecular weight of the polyol (a) is not particularly limited. From the viewpoint of realizing low resilience, the number average molecular weight of the polyol (a) is preferably 20,000 or less, more preferably 15,000 or less, even more preferably 10,000 or less, even more preferably 7,000 or less, and even more preferably 5,000 or less. The lower limit of the number average molecular weight of the polyol (a) is usually 2,000 or more, and may be 1,000 or more. The number average molecular weight of the polyol (a) can be measured by gel permeation chromatography (GPC). When the polyol (a) is a commercially available product, the catalog value may be used as the number average molecular weight of the polyol (a).

[0029] The number of functional groups of the polyol (a) is not particularly limited. From the viewpoint of reducing the stress relaxation rate and the hysteresis loss rate, the number of functional groups of the polyol (a) is preferably less than 3, more preferably 2.5 or less, and even more preferably 2. The number of functional groups of the polyol (a) is usually 2 or more. The polyol (a) is preferably a polyoxyethylene / propylene glycol copolymer having an EO unit content of 50 mol% or more. If the number of functional groups in the polyol (a) is within the above range, the formation of a network structure can be suppressed when the polyol reacts with the isocyanate. It is presumed that the polyurethane foam thus formed will have suppressed entanglement of polyurethane molecules during compression, resulting in reduced stress relaxation rate and hysteresis loss rate. In the present disclosure, the functionality refers to the average number of active hydrogen groups possessed by each component contained in the polyol. When the polyol is a commercially available product, the catalog value may be used as the functionality of the polyol (a).

[0030] The content of polyol (a) is not particularly limited. The content of polyol (a) is more than 0 parts by mass, preferably 20 parts by mass or more, more preferably 40 parts by mass or more, 50 parts by mass or more, 60 parts by mass or more, 70 parts by mass or more, or 80 parts by mass or more, when the total amount of polyols is 100 parts by mass. The upper limit of the content of polyol (a) is preferably 95 parts by mass or less, more preferably 93 parts by mass or less, and even more preferably 90 parts by mass or less, from the viewpoint of moldability. From these viewpoints, the content of polyol (a) is preferably 20 parts by mass or more and 95 parts by mass or less, and can be within a range that appropriately combines the above lower and upper limits.

[0031] The polyol may contain a polyol other than the polyol (a) (hereinafter, also simply referred to as "other polyol"). The other polyol is not particularly limited as long as it is a polyol having an ethylene oxide unit content of less than 50 mol% (it may not contain ethylene oxide units). As the other polyol, for example, a polyether polyol having an ethylene oxide unit content of less than 50 mol%, a polymer polyol having an ethylene oxide unit content of less than 50 mol%, a polyester polyol, etc. can be used. From the viewpoint of various physical properties such as impact absorption, the other polyol is preferably a polyether polyol having an ethylene oxide unit content of less than 50 mol%. Only one type of other polyol may be used, or two or more types may be used in combination.

[0032] The number of functional groups of the other polyol is not particularly limited. The number of functional groups of the other polyol is preferably less than 3, more preferably 2.5 or less, and even more preferably 2. The number of functional groups of the other polyol is usually 2 or more. If the number of functional groups of the other polyol is within the above range, the formation of a network structure during the reaction between the polyol and the isocyanate can be suppressed. It is presumed that the polyurethane foam thus formed will have reduced entanglement of polyurethane molecules during compression, resulting in reduced stress relaxation rate and hysteresis loss rate. The number average molecular weight of the other polyol is not particularly limited, and is preferably 2,000 or more and 20,000 or less, more preferably 2,500 or more and 15,000 or less, and even more preferably 3,000 or more and 10,000 or less.

[0033] Examples of other polyols include polyether polyols containing PO units, butylene oxide units, etc., as alkylene oxide units other than EO units. Hereinafter, this polyether polyol will be referred to as polyol (b). As polyol (b), polyoxyethylene / propylene glycol copolymers, polypropylene glycol (PPG), and polytetramethylene glycol (PTMG) having an EO unit content of less than 50 mol% are preferred, and polyoxyethylene / propylene glycol copolymers having an EO unit content of less than 50 mol% are more preferred. As other polyols, polyols other than polyol (b) may be used as long as the properties of the polyurethane foam, such as rebound resilience, stress relaxation rate, and hysteresis loss rate, are not impaired. Polyols other than polyol (b) may be used alone or in combination of two or more.

[0034] The content of EO units in polyol (b) is not particularly limited. For example, from the viewpoint of reducing the stress relaxation rate and the hysteresis loss rate, the content of EO units in polyol (b) is preferably more than 0 mol%, more preferably 10 mol% or more, and even more preferably 15 mol% or more. The upper limit of the content of EO units in polyol (b) is not particularly limited, and may be less than 50 mol%.

[0035] The content of polyol (b) is not particularly limited. From the viewpoint of improving cushioning, the content of polyol (b) is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and even more preferably 12 parts by mass or more, when the total amount of polyols is 100 parts by mass. From the viewpoint of ensuring a sufficient amount of polyol (a) to ensure surface softness, the content of polyol (b) is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. From these viewpoints, the content of polyol (b) is preferably 5 parts by mass or more and 50 parts by mass or less, more preferably 8 parts by mass or more and 40 parts by mass or less, and even more preferably 12 parts by mass or more and 30 parts by mass or less.

[0036] When polyol (a) and polyol (b) are used in combination, the cushioning properties of the polyurethane foam can be improved. The reason for this is not clear, but is presumed to be as follows. When only polyol (a) is used as the polyol, a foam with poor cushioning and roughness is obtained. When only polyol (a) is used as the polyol, the polyol components become homogenized, and the reaction proceeds quickly, which is thought to be one of the reasons for the reduced cushioning. It is presumed that by using polyol (a) in combination with polyol (b), a polyether polyol with properties different from polyol (a), the reaction can be slowed down, resulting in improved cushioning.

[0037] (1.2) Foaming agent The blowing agent is an optional component. Water, alternative chlorofluorocarbons, or hydrocarbons such as pentane can be used alone or in combination as the blowing agent. Water is particularly preferred as the blowing agent. When water is used, carbon dioxide gas is generated during the reaction between the polyol and the isocyanate, and the carbon dioxide gas causes foaming. The amount of water used as the blowing agent is preferably 1.0 to 4.0 parts by mass, more preferably 1.5 to 3.5 parts by mass, and even more preferably 2.0 to 3.0 parts by mass, per 100 parts by mass of the polyol.

[0038] (1.3) Catalyst The catalyst is an optional component. Known catalysts for polyurethane foams can be used. Examples of catalysts include resinification catalysts and foaming catalysts. The resinification catalyst is a catalyst that promotes the urethane reaction (resinification reaction) between polyol and isocyanate. The resinification catalyst is not limited, and examples thereof include amine catalysts such as triethylenediamine, 1,2-dimethylimidazole, N·(N',N'-dimethylaminoethyl)-morpholine, tetramethylguanidine, dimethylaminoethanol, N-methyl-N'-(2-hydroxyethyl)-piperazine, N,N,N',N'-tetramethylpropane-1,3-diamine, N,N'-dimethylpiperazine, N,N,N',N'-tetramethylhexane-1,6-diamine, N,N,N',N",N"-pentamethyldipropylene-triamine, N-(2-hydroxyethyl)morpholine, ethylene glycol bis(3-dimethyl)-aminopropyl ether, N,N-dimethylcyclohexylamine, and N-methyl-N'-(2-dimethylamino)ethylpiperazine. The foaming catalyst promotes the reaction between isocyanate and water to generate carbon dioxide gas. The foaming catalyst is not limited, and examples thereof include amine catalysts such as bis(2-dimethylaminoethyl) ether, triethylamine, dimethylaminoethoxyethanol, N,N,N'-trimethylaminoethyl-ethanolamine, and N,N,N',N",N"-pentamethyldiethylenetriamine. The total amount of the catalyst is preferably 0.2 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of the polyol.

[0039] (1.4) Foam stabilizer The foam stabilizer is an optional component. The foam stabilizer may be any foam stabilizer that is commonly used as a raw material for urethane foam, such as a silicone compound or a nonionic surfactant. The amount of the foam stabilizer is preferably 0.05 to 2.0 parts by mass per 100 parts by mass of the polyol.

[0040] (1.5) Crosslinking agent The crosslinking agent is an optional component and is blended to improve the hardness and tear strength of the polyurethane foam, and is particularly effective in increasing hardness. Examples of crosslinking agents include polyhydric alcohols such as trimethylolpropane, glycerin, 1,4-butanediol, and diethylene glycol, and amines such as ethanolamines and polyethylene polyamines. Two or more types of crosslinking agents may be used. The total amount of crosslinking agents is preferably 0.1 to 6.0 parts by mass per 100 parts by mass of polyol.

[0041] (1.6) Isocyanates The isocyanate is not particularly limited. As the isocyanate, an MDI-based isocyanate (diphenylmethane diisocyanate-based isocyanate) is preferred. When an MDI-based isocyanate is used, the surface 10A of the polyurethane foam can have a softer feel than when, for example, TDI (toluene diisocyanate) is used. Specific examples of MDI-based isocyanates include monomeric MDI such as 2,2'-diphenylmethane diisocyanate (2,2'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), and 4,4'-diphenylmethane diisocyanate (4,4'-MDI), polymeric MDI, which is a mixture of diphenylmethane diisocyanate and polymethylene polyphenylene polyisocyanate, and carbodiimide-modified, urethane-modified, urea-modified, allophanate-modified, biuret-modified, and isocyanurate-modified versions of these, as well as MDI prepolymers obtained by reacting these isocyanates with polyols. Multiple types of MDI-based isocyanates may be used in combination. Among these, the isocyanate preferably contains carbodiimide-modified diphenylmethane diisocyanate, more preferably contains monomeric MDI and carbodiimide-modified diphenylmethane diisocyanate, and even more preferably is a mixture of monomeric MDI and carbodiimide-modified diphenylmethane diisocyanate with polymeric MDI. From the viewpoint of suppressing the formation of a network structure during the reaction of polyol with isocyanate, the total amount of monomeric MDI and carbodiimide-modified diphenylmethane diisocyanate is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 80 parts by mass or more, based on 100 parts by mass of the total amount of isocyanate. The upper limit of the total amount of monomeric MDI and carbodiimide-modified diphenylmethane diisocyanate is not particularly limited and may be 100 parts by mass. The mass ratio of the total amount of monomeric MDI and carbodiimide-modified diphenylmethane diisocyanate to the amount of polymeric MDI is preferably 60:40-100:0, more preferably 70:30-98:2, and even more preferably 80:20-96:4.

[0042] The isocyanate index (INDEX) is preferably 80 or more, more preferably 90 or more, more preferably 97 or more, and particularly preferably 100 or more. The isocyanate index is preferably 120 or less, more preferably 110 or less. The isocyanate index can be, for example, within a range that combines the above upper and lower limits, for example, 97 or more and 120 or less. The isocyanate index is the value obtained by dividing the number of moles of isocyanate groups in an isocyanate by the total number of moles of active hydrogen groups such as hydroxyl groups in a polyol and water used as a blowing agent, and multiplying the result by 100, and is calculated as [NCO equivalent of isocyanate / active hydrogen equivalent x 100].

[0043] (1.7) Other ingredients Other additives that may be added as needed include, for example, flame retardants and colorants.

[0044] Flame retardants are blended into polyurethane foams to reduce their flammability. Examples of flame retardants include known liquid and solid flame retardants. Examples include halogenated polymers such as polyvinyl chloride, chloroprene rubber, and chlorinated polyethylene; organic flame retardants such as phosphate esters and halogenated phosphate ester compounds; melamine resins and urea resins; and inorganic flame retardants such as antimony oxide and aluminum hydroxide. The flame retardant is not limited to one type, and two or more types may be used in combination. The total amount of flame retardants is preferably 0.1 to 6.0 parts by mass per 100 parts by mass of polyol. The coloring agent is blended to give the polyurethane foam an appropriate color, and a coloring agent according to the desired color is used. Examples of the coloring agent include pigments and graphite.

[0045] (2) Physical properties of the seat pad 10 In the present disclosure, the surface of the seat pad 10 facing the occupant when the occupant is seated thereon is referred to as the front surface 10A of the seat pad 10, and the surface opposite the front surface 10A is referred to as the back surface 10B of the seat pad 10. For example, when molding the seat pad 10 using a molding die, the front surface 10A of the seat pad 10 can be suitably molded as the surface that contacts the bottom surface of a lower mold. When the seat pad 10 is mounted on a vehicle, the front surface 10A of the seat pad 10 normally faces upward. In FIG. 1, the upper side is indicated by an arrow UP, and the lower side is indicated by an arrow DW.

[0046] The size and shape of the seat pad 10 are not particularly limited as long as they can support the buttocks and the like (for example, buttocks, back, and lumbar region) of the seated person. The thickness of the portion of the seat pad 10 that supports the buttocks of the seated person is, for example, 20 mm or more, 30 mm or more, preferably 40 mm or more, more preferably 50 mm or more, and even more preferably 60 mm or more. The thickness of the above portion of the seat pad 10 is usually 120 mm or less, and may be, for example, 100 mm or less, 80 mm or less, 75 mm or less, or 70 mm or less. The characteristics relating to the softness of the surface of the seat pad 10 described below are the results of measurements on a test piece, but similar characteristics are also shown in the shape of the product.

[0047] (2.1) Asker F hardness (surface softness) 2, the seat pad 10 is divided into five equal parts in the thickness direction between the front surface 10A and the back surface 10B, and is composed of a first layer 11, a second layer 12, a third layer 13, a fourth layer 14, and a fifth layer 15, in that order from the front surface 10A side, and when the Asker F hardness of the third layer 13 measured from the front surface 10A side is F3 and the Asker F hardness of the first layer 11 measured from the front surface 10A side is F1, the seat pad 10 satisfies the following formula (1). From the viewpoint of maintaining the posture of a seated person while ensuring the softness of the surface, it is preferable that the seat pad 10 satisfy any of the following formulas (2) to (4). F1 / F3<1.0 (1) F1 / F3≦0.85 (2) F1 / F3≦0.70 (3) F1 / F3≦0.65 (4) Furthermore, the seat pad 10 may satisfy, for example, any one of the following formulas (5) to (7). 0.20≦F1 / F3 (5) 0.30≦F1 / F3 (6) 0.40≦F1 / F3 (7) From these viewpoints, the seat pad 10 preferably satisfies 0.20≦F1 / F3≦0.85, more preferably satisfies 0.30≦F1 / F3≦0.70, and further preferably satisfies 0.40≦F1 / F3≦0.65.

[0048] The Asker F hardness is measured using an Asker F hardness tester. The Asker F hardness tester is attached to the test piece, and the value is read after 20 seconds. The test piece for measuring the Asker F hardness is a square plate measuring 400 mm in length and width. The thickness of the test piece is the thickness of the seat pad 10 divided into five equal parts in the thickness direction. The Asker F hardness F1 is measured by attaching the Asker F hardness tester to the center of the surface 10A of the first layer 11. The Asker F hardness F3 is measured by attaching the Asker F hardness tester to the center of the surface 10A of the third layer 13. In the following description, the Asker F hardness measured from the surface 10A side of the second layer 12 is referred to as F2, and the Asker F hardness measured from the surface 10A side of the fourth layer 14 is referred to as F4. The Asker F hardness F2 is measured by placing an Asker F hardness tester at the center of the surface of the second layer 12 on the front surface 10A side. The Asker F hardness F4 is measured by placing an Asker F hardness tester at the center of the surface of the fourth layer 14 on the front surface 10A side. The Asker F hardness F5 of the fifth layer 15 is measured from the back surface 10B side. The Asker F hardness F5 is measured by placing an Asker F hardness tester at the center of the back surface 10B of the fifth layer 15.

[0049] The Asker F hardness of each layer of the seat pad 10 is not particularly limited as long as it satisfies the above requirements. The Asker F hardness of each layer of the seat pad 10 may further satisfy one or more of the following requirements. From the viewpoint of maintaining the posture of a seated occupant while ensuring the softness of the surface, it is preferable that the seat pad 10 satisfy F1 / F2<1.0. With this configuration, sufficient hardness can be ensured in a portion that is at least 1 / 5 of the thickness of the seat pad 10 from the surface, and it is possible to preferably realize a seat pad 10 in which only the surface layer portion that accounts for 20% or less of the total thickness is soft. Furthermore, the seat pad 10 may satisfy any of the formulas (8)-(10). 0.30≦F1 / F2≦0.85 (8) 0.30≦F1 / F2≦0.70 (9) 0.40≦F1 / F2≦0.65 (10)

[0050] The seat pad 10 may satisfy any one of the following formulas (11)-(13) from the viewpoint of ensuring the hardness of the back surface 10B side of the seat pad 10 while ensuring the softness of the front surface. When any one of the formulas (11)-(13) is satisfied, the posture of the seated person can be maintained favorably, for example, without placing a separate polyurethane foam (a so-called slab) on the back surface 10B side that is harder than the front surface 10A side. 0.55≦F1 / F5≦0.90 (11) 0.60≦F1 / F5≦0.85 (12) 0.65≦F1 / F5≦0.80 (13)

[0051] More specifically, the seat pad 10 is preferably made of polyurethane foam that exhibits the following hardness when a square prism-shaped sample measuring 400 mm in length, 400 mm in width, and 100 mm in thickness is prepared and the Asker F hardness of each layer is measured. From the viewpoint of surface softness, the Asker F hardness F1 is preferably 60 or less, more preferably 50 or less, and even more preferably 40 or less. From the viewpoint of ease of production, the Asker F hardness F1 is preferably 12 or more, more preferably 15 or more, and even more preferably 20 or more. From these viewpoints, the Asker F hardness F1 is preferably 12 or more and 60 or less, more preferably 15 or more and 50 or less, and even more preferably 20 or more and 40 or less. From the viewpoint of maintaining the posture of a seated occupant, the Asker F hardness F3 is preferably 18 or more, more preferably 20 or more, and even more preferably 30 or more. From the viewpoint of ease of manufacture, the Asker F hardness F3 is preferably 80 or less, more preferably 75 or less, and even more preferably 70 or less. From these viewpoints, the Asker F hardness F3 is preferably 18 or more and 80 or less, more preferably 20 or more and 75 or less, and even more preferably 30 or more and 70 or less. From the viewpoint of the softness of the surface and maintaining the posture of the seated occupant, the absolute value of the difference between F1 and F3 (|F3-F1|) is preferably 4 or more, and may be 10 or more, 15 or more, 20 or more, or 25 or more. The upper limit of the absolute value of the difference between F1 and F3 is not particularly limited, and may be, for example, 50 or less, 45 or less, or 40 or less.

[0052] From the viewpoint of maintaining the posture of a seated person and ease of manufacturing, the Asker F hardness F2 is preferably 18 or more and 80 or less, more preferably 20 or more and 75 or less, and even more preferably 30 or more and 70 or less. From the viewpoint of ensuring the hardness of the back surface 10B side of the seat pad 10 and ease of manufacturing, the Asker F hardness F4 is preferably 18 or more and 80 or less, more preferably 20 or more and 75 or less, and even more preferably 30 or more and 70 or less. From the viewpoint of ensuring the hardness of the back surface 10B side of the seat pad 10 and ease of manufacturing, the Asker F hardness F5 is preferably 15 or more and 65 or less, more preferably 18 or more and 60 or less, and even more preferably 25 or more and 55 or less. From the viewpoint of maintaining the posture of a seated occupant, the absolute value of the difference between F2 and F3 (|F3-F2|) is preferably 6 or less, and more preferably 5 or less. The lower limit of the absolute value of the difference between F2 and F3 is 0. From the viewpoint of maintaining the posture of a seated occupant, the absolute value of the difference between F4 and F3 (|F3-F4|) is preferably 5 or less, and more preferably 4 or less. The lower limit of the absolute value of the difference between F4 and F3 is 0.

[0053] The Asker F hardness of each layer of the seat pad 10 can be controlled by, for example, adjusting the types of components contained in the polyurethane foam composition, the blending ratio of each component, etc. For example, increasing the amount of foaming agent added can increase the Asker F hardness F3 of the third layer 13 while maintaining the Asker F hardness F1 of the first layer 11. For example, decreasing the amount of crosslinking agent added can increase the Asker F hardness F3 of the third layer 13 while maintaining the Asker F hardness F1 of the first layer 11. Furthermore, increasing the isocyanate index tends to decrease the F1 / F3 ratio. Furthermore, when the seat pad 10 is a molded foam, the reactivity during molding can be adjusted by appropriately setting the orientation of the mold relative to the vertical direction, thereby controlling the Asker F hardness of each layer. The hardness of each layer of the seat pad 10 exhibits similar characteristics when a hardness measurement method such as 25% hardness (compliant with JIS K6400-2 (2012 edition) Method D) is used in addition to the above-mentioned hardness measurement method.

[0054] (2.2) Density The density of the center portion of the seat pad 10, excluding the front surface 10A and the back surface 10B, is not particularly limited. From the viewpoint of weight reduction, the density is preferably 100 kg / m 3 More preferably, it is 80 kg / m or less. 3 More preferably, it is 75 kg / m or less. 3 The lower limit of the density is not particularly limited, but is usually 20 kg / m 3 From these viewpoints, the density is preferably 20 kg / m 3 More than 100kg / m 3 The range may be any range that is an appropriate combination of the above lower and upper limits. The density of the central portion excluding the front surface 10A and the back surface 10B can be measured as follows. A rectangular parallelepiped test piece 100 mm long, 100 mm wide, and 50 mm high, excluding the skin, is taken from the center of the seat pad 10. The height direction of the test piece is aligned with the front and back directions of the seat pad 10. The mass of the taken test piece is measured, and the mass of the test piece is divided by the volume to determine the density (kg / m) of the center. 3) is calculated.

[0055] (2.3) 25% hardness There are no particular limitations on the 25% hardness (based on JIS K6400-2 (2012 edition) Method D) of the seat pad 10. The 25% hardness of the entire seat pad 10 is preferably 80 N or more and 400 N or less, more preferably 120 N or more and 300 N or less, and even more preferably 160 N or more and 280 N or less. The test specimen for hardness measurement is a rectangular parallelepiped measuring 400 mm in length and 400 mm in width, including the front and back skins. For example, in Experimental Examples 1-6, 8-10 described later, the test specimen is a rectangular parallelepiped measuring 400 mm in length, 400 mm in width, and 100 mm in height, including the skins. In Experimental Example 7 described later, the test specimen is a rectangular parallelepiped measuring 400 mm in length, 400 mm in width, and 50 mm in height, including the skins. A pressure plate with a diameter of 200 mm is used for measurement. During measurement, the test specimen is placed on the support plate of the testing machine so that the center of the test specimen is at the center of the pressure plate.

[0056] (2.4) Hysteresis loss rate From the viewpoint of durability, the hysteresis loss rate of the seat pad 10 (based on JIS K6400-2 (2012 edition) Method E) is preferably 22% or less, and more preferably 20% or less, and may be 18% or less, or 15% or less. The lower limit of the hysteresis loss rate is not particularly limited, but is usually 5.0% or more. When plotting a force-deflection curve based on JIS K6400-2 (2012 edition) Method E, the load required to return from pressure to pressure during compression of the seat pad is set to 980 N. The test specimens used for the measurements are obtained as follows. The entire seat pad 10 including the skin is used as the test specimen. For example, in Experimental Examples 1-6, 8-10 described later, a rectangular parallelepiped including the skin, measuring 400 mm in length, 400 mm in width, and 100 mm in height, is used as the test specimen. In Experimental Example 7 described later, a rectangular parallelepiped including the skin, measuring 400 mm in length, 400 mm in width, and 50 mm in height, is used as the test specimen. The height direction of the test specimen is aligned with the front-to-back direction of the seat pad 10.

[0057] (2.5) Compression deflection coefficient The compression deflection coefficient of the seat pad 10 (based on JIS K6400-2 (2012 edition) E method) is preferably 2.9 or less from the viewpoint of reducing the feeling of bottoming out, and may be 2.7 or less, or 2.5 or less. The lower limit of the compression deflection coefficient of the seat pad 10 is not particularly limited, and may be, for example, 2.0 or more, or 2.2 or more. The test specimen used for the measurement and the method for obtaining the force-deflection curve are the same as those used for (2.4) Hysteresis loss rate measurement.

[0058] (2.6) Stress relaxation rate From the viewpoint of durability, the stress relaxation rate of the seat pad 10 is preferably 24% or less, more preferably 20% or less, and even more preferably 15% or less, and may be 12% or less, 10% or less, 9.0% or less, or 8.0% or less. The lower limit of the stress relaxation rate is not particularly limited and may be, for example, 1.0% or more. The smaller the stress relaxation rate, the less urethane will sag after sitting, resulting in better durability. The thinner the thickness of the seat pad 10, the greater the stress relaxation rate tends to be. The technology disclosed herein is particularly useful in that it can reduce the stress relaxation rate even in a thin seat pad 10. The stress relaxation rate (%) can be measured as follows. The entire seat pad 10, including the skin, was used as the test specimen. For example, in Experimental Examples 1-6, 8-10 described below, a rectangular parallelepiped (400 mm long, 400 mm wide, and 100 mm high) including the skin was used as the test specimen. In Experimental Example 7 described below, a rectangular parallelepiped (400 mm long, 400 mm wide, and 50 mm high) including the skin was used as the test specimen. The height direction of the test specimen was aligned with the front and back directions of the seat pad 10. A circular pressure plate with a diameter of 200 mm was used to compress the polyurethane foam at a rate of 50 mm / min through a distance of 75% of the initial thickness. The load was then removed and the test specimen was left for 1 minute. The load was then applied again at the same rate, and the pressure plate was stopped when a load of 196 N (20 kgf) was reached. The load was then read after 5 minutes of rest. The stress relaxation rate was then calculated using the following formula: Stress relaxation rate (%) = 100 x [load when pressure plate is stopped (196N) - load after leaving for 5 minutes] / load when pressure plate is stopped (196N)

[0059] (2.7) Rebound Resilience From the viewpoint of improving ride comfort, the rebound resilience of the seat pad 10 (based on JIS K6400-3 (2011 edition)) is preferably 70% or less, more preferably 60% or less, even more preferably 55% or less, and may be 50% or less, 46% or less, or 44% or less. The lower limit of the rebound resilience of the seat pad 10 is not particularly limited, and may be, for example, 10% or more, 20% or more, or 30% or more.

[0060] 5. Manufacturing method of seat pad 10 The seat pad 10 can be produced by a known foaming method in which the composition is stirred and mixed to react the polyol and isocyanate. Foaming methods include slab foaming and mold foaming, and either molding method is acceptable. The seat pad 10 is preferably a molded foam. Molded foaming is a method in which the mixed composition is filled into a mold (forming die) and foamed within the mold. When the seat pad 10 is a molded foam, from the viewpoint of surface softness, it is preferable that the front surface 10A is the surface that contacts the lower surface of the molding space, and the back surface 10B is the surface that contacts the upper surface of the molding space.

[0061] 6. Effects of this embodiment In recent years, ensuring ride comfort has become an issue as seat pads 10 for automobiles, ships, aircraft, etc. have become thinner and lighter. Ride comfort performance includes the softness of the surface, which improves the feel of the seat when seated, and durability, which maintains the posture of the seated person. The seat pad 10 of this embodiment has excellent surface softness, providing a pleasant feel. Furthermore, the seat pad 10 of this embodiment can ensure hardness in the central portion in the thickness direction, providing excellent durability for maintaining the posture of a seated occupant. For example, the seat pad 10 of this embodiment can ensure ride comfort even without a so-called floor slab, contributing to a lighter, thinner, and more cost-effective seat pad 10. Furthermore, according to this embodiment, the hysteresis loss rate and stress relaxation rate can be reduced, and a highly durable seat pad 10 that is resistant to sagging can be realized (see FIG. 1). [Example]

[0062] The present disclosure will be specifically described below using examples. In Tables 1 and 2, when an "*" is added, such as "Experimental Example 1*," it indicates that it is a comparative example. Experimental Examples 3 to 10 are examples, and Experimental Examples 1 and 2 are comparative examples. 1. Sample Preparation Compositions were prepared according to the proportions shown in Table 1, and samples for each experiment were produced by mold foaming. The samples for Experiments 1-6 and 8-10 were square prisms measuring 400 mm in length, 400 mm in width, and 100 mm in thickness. The sample for Experiment 7 was square prism measuring 400 mm in length, 400 mm in width, and 50 mm in thickness.

[0063] Details of the main ingredients are as follows: Polyol (a): Polyoxyethylene / propylene glycol copolymer, EO unit content 80 mol%, PO unit content 20 mol%, number average molecular weight 4000, functionality 2, hydroxyl value 28 mg / KOHg Polyol (b): Polyoxyethylene / propylene glycol copolymer, EO unit content 20 mol%, PO unit content 80 mol%, number average molecular weight 4000, functionality 2, hydroxyl value 28 mg / KOHg Polyol (c): Polyether polyol, EO unit content 15 mol%, number average molecular weight 7000, functionality 3, hydroxyl value 24 mg / KOHg Polyol (d): Polymer polyol, EO unit content 15 mol%, number average molecular weight 5000, number of functional groups 3, hydroxyl value 24 mg / KOHg Polyol (e): Polyether polyol, EO unit content 15 mol%, number average molecular weight 5000, functionality 3, hydroxyl value 34 mg / KOHg

[0064] Foaming agent: Water Catalyst 1: Resin catalyst, triethylenediamine 33% Catalyst 2: Foaming catalyst, bis(2-dimethylaminoethyl) ether

[0065] Foam stabilizer 1: Silicone foam stabilizer, product number L-3184J, manufactured by MOMENTIVE Foam stabilizer 2: Silicone foam stabilizer, product number: B8715LF2, manufactured by EVONIK Foam stabilizer 3: Silicone foam stabilizer, product number: B8738LF2, manufactured by EVONIK Crosslinker 1: Trimethylolpropane trimethacrylate Crosslinker 2: Glycerin Crosslinker 3: N,N-diethanolamine 80%

[0066] Isocyanate 1: 95% mixture of monomeric MDI (4,4'-MDI) and carbodiimide-modified diphenylmethane diisocyanate, and 5% mixture of polymeric MDI Isocyanate 2: A mixture of 80% toluene diisocyanate (TDI) and 20% polymeric MDI

[0067] [Table 1] [Table 2]

[0068] 2. Evaluation Method 1 Test pieces were cut out from the polyurethane foams produced using the above raw materials, and the hysteresis loss rate, stress relaxation rate, rebound resilience, etc. were measured using the methods described below. The results are shown in Tables 1 and 2. Note that in Experimental Example 2, the physical properties were not evaluated because the foam could not be demolded. (1) Density Density (kg / m 3 ) was measured by the method described in the embodiment. (2) 25% hardness The 25% hardness (N) was measured by the method described in the embodiment. That is, the 25% hardness was measured by the method described in the embodiment. That is, in Experimental Examples 1-6 and 8-10, the test specimen was a rectangular parallelepiped having a length of 400 mm, a width of 400 mm, and a height of 100 mm, including the skin. In Experimental Example 7, the test specimen was a rectangular parallelepiped having a length of 400 mm, a width of 400 mm, and a height of 50 mm, including the skin. (3) Hysteresis loss rate The hysteresis loss rate (%) was measured in accordance with JIS K6400-2 Method E. The smaller the value, the better the posture stability (durability) when sitting. (4) Compression deflection coefficient The compression deflection coefficient (%) was measured in accordance with JIS K6400-2 Method E. The smaller the value, the better the vibration absorption properties. (5) Stress relaxation rate The stress relaxation rate (%) was measured by the method described in the embodiment. The smaller the value, the better the posture stability (durability) when sitting. (6) Rebound elasticity The rebound resilience (%) was measured in accordance with JIS K6400-3 (2011 edition). By controlling the rebound resilience appropriately, ride comfort can be improved.

[0069] 3. Evaluation Method 2 A sample made using the above raw materials was divided into five equal parts in the thickness direction, and the Asker F hardness of each layer was measured using the method described in the embodiment, and the ratio of the Asker F hardness of the first layer to the Asker F hardness of each layer was calculated. The results are shown in Tables 1 and 2. (1) Asker F hardness The Asker F hardness of each of the first to fifth layers was measured by the method described in the embodiment. (2) Ratio of the Asker F hardness of the first layer to the Asker F hardness of each layer The ratio of the Asker F hardness of the first layer to the Asker F hardness of each layer was calculated by dividing the Asker F hardness of the first layer by the Asker F hardness of each layer. In Tables 1 and 2, for example, "1st Layer / 3rd Layer" shows the ratio of the Asker F hardness of the first layer to the Asker F hardness of the 3rd layer.

[0070] 4.Result 1 Experimental Example 3-10 satisfies the following requirements (a) to (c). Requirement (a): The seat pad is made of polyurethane foam obtained from a composition containing a polyol and an isocyanate. Requirement (b): The polyol includes a polyol having an ethylene oxide unit content of 50 mol % or more when the total amount of alkylene oxide units is taken as 100 mol %. · Requirement (c): F1 / F3<1 is met. Note that Experimental Example 1 does not satisfy requirements (b) and (c). Experimental Example 2 does not satisfy requirement (a). Experimental Example 3-10, which satisfies requirements (a) to (c), had better surface softness and durability than Comparative Example 1. Experimental Example 3-10, which satisfies requirements (a) to (c), exhibited the following characteristics: first layer (F1) < fifth layer (F5) < third layer (F3).

[0071] Among Experimental Examples 3-10, Experimental Example 4-10 also satisfied the following requirement (d): Experimental Example 4-10, which also satisfied requirement (d), had even better surface softness. · Requirement (d): 0.30≦F1 / F3≦0.70 is satisfied. Furthermore, Experimental Example 3-10 also satisfied the following requirement (e): Experimental Example 3-10, which further satisfied requirement (e), suitably yielded a polyurethane foam having good surface softness and durability. Requirement (e): The isocyanate contains carbodiimide-modified diphenylmethane diisocyanate.

[0072] Moreover, Experimental Example 3-10 also satisfied the following requirement (f): Experimental Example 3-10, which also satisfied requirement (f), had good vibration absorption properties. Requirement (f): The compression deflection coefficient measured in accordance with JIS K6400-2 (2012 edition) Method E is 2.8 or less. Among Experimental Examples 3-10, Experimental Example 4-10 also satisfied the following requirement (g): Experimental Example 4-10, which also satisfied requirement (g), was excellent in ride comfort performance. Requirement (g): The rebound resilience measured in accordance with JIS K6400-3 (2011 edition) is 55% or less. Among Experimental Examples 3-10, Experimental Examples 3-8 and 10 also satisfied the following requirement (h): Experimental Examples 3-8 and 10, which also satisfied requirement (h), had good durability. Requirement (h): The stress relaxation rate is 15% or less. Among Experimental Examples 3-10, Experimental Examples 4-7 and 10 also satisfied the following requirement (i): Experimental Examples 4-7 and 10, which also satisfied requirement (i), had good durability. Requirement (i): The hysteresis loss rate measured in accordance with JIS K6400-2 (2012 edition) Method E is 20% or less.

[0073] Experimental Example 5 is compared with Experimental Example 4, which contains a smaller amount of foaming agent than Experimental Example 5. The Asker F hardness of the first layer is approximately the same for Experimental Example 5 and Experimental Example 4. The ratio of the first layer to the third layer (F1 / F3) for Experimental Example 5 is smaller than that for Experimental Example 4. These results suggest that increasing the amount of foaming agent added can improve the softness and durability of the surface. Furthermore, it is suggested that the technology of the present disclosure is effective even when the density of the seat pad is reduced.

[0074] Experimental Example 5 is compared with Experimental Example 6, which added a larger amount of crosslinking agent than Experimental Example 5. The Asker F hardness of the first layer was approximately the same for Experimental Example 5 and Experimental Example 6. The ratio of the first layer to the third layer (F1 / F3) for Experimental Example 5 was smaller than that for Experimental Example 6. These results suggest that the softness and durability of the surface can be improved by reducing the amount of additive.

[0075] Experimental Example 5, which has a thickness of 100 mm, is compared with Experimental Example 7, which has a thickness of 50 mm. Although the Asker F hardness of each layer in Experimental Example 7 is smaller than the Asker F hardness of the layers in the same position in Experimental Example 5, Experimental Example 7 also exhibited the following characteristics: first layer (F1) < fifth layer (F5) < third layer (F3), just like Experimental Example 5. These results suggest that the technology of the present disclosure is also effective for thin seat pads.

[0076] Experimental Example 4 is compared with Experimental Example 8, which has a lower density than Experimental Example 4. Although the Asker F hardness of each layer in Experimental Example 8 is slightly lower than the Asker F hardness of the layers at the same positions in Experimental Example 4, Experimental Example 8 also exhibited the same characteristics as Experimental Example 4: first layer (F1) < fifth layer (F5) < third layer (F3). These results suggest that the technology of the present disclosure is also effective for low-density seat pads.

[0077] Experimental Example 5 with an isocyanate index of 105, Experimental Example 3 with an isocyanate index of 85, and Experimental Example 10 with an isocyanate index of 95 are compared. The first layer / third layer (F1 / F3) ratio of Experimental Example 3 was 0.750. The first layer / third layer (F1 / F3) ratio of Experimental Example 10 was 0.651. The first layer / third layer (F1 / F3) of Experimental Example 5 was 0.493. These results suggest that the larger the isocyanate index, the more the surface softness can be improved.

[0078] Experimental Examples 5 and 9, which differ in the blending ratio of polyols, are compared. The polyol ratio in Experimental Example 5 was polyol (a):polyol (b) = 85:15. The polyol ratio in Experimental Example 9 was polyol (a):polyol (b) = 60:40. Although the Asker F hardness of each layer in Experimental Example 9 was greater than that of the layers at the same position in Experimental Example 5, Experimental Example 9 also exhibited the same characteristics as Experimental Example 5: first layer (F1) < fifth layer (F5) < third layer (F3). The stress relaxation rate of Experimental Example 5, 7.7%, was smaller than the stress relaxation rate of Experimental Example 9, 18.4%. These results suggest that a higher content of polyol (a) can further improve durability.

[0079] The following inventions can also be understood from the above experimental examples. The above descriptions are used to explain the specific aspects of the invention below. A polyurethane foam obtained from a composition comprising a polyol and an isocyanate, The polyol includes a polyol having an ethylene oxide unit content of 50 mol % or more when the total amount of alkylene oxide units is taken as 100 mol %, The polyurethane foam has an isocyanate index of 97 or greater. A polyurethane foam obtained from a composition comprising a polyol and an isocyanate, The polyol includes a polyol having an ethylene oxide unit content of 50 mol % or more when the total amount of alkylene oxide units is taken as 100 mol %, A polyurethane foam that satisfies at least one of the above requirements (e), (f), (g), (h), and (i).

[0080] 5.Result 2 Experimental Example 3-10 satisfies requirements (a) and (f). Requirement (a): The seat pad is made of polyurethane foam obtained from a composition containing a polyol and an isocyanate. Requirement (f): The compression deflection coefficient measured in accordance with JIS K6400-2 (2012 edition) Method E is 2.8 or less. Note that Experimental Example 1 does not satisfy requirement (f). Experimental Example 3-10, which satisfies requirements (a) and (f), showed good deflection and was less likely to feel like hitting the bottom compared to Comparative Example 1.

[0081] Among Experimental Examples 3-10, Experimental Example 4-10 also satisfied the following requirement (g): Experimental Example 4-10, which also satisfied requirement (g), was excellent in ride comfort performance. Requirement (g): The rebound resilience measured in accordance with JIS K6400-3 (2011 edition) is 55% or less. Among Experimental Examples 3-10, Experimental Examples 3-8 and 10 also satisfied the following requirement (h): Experimental Examples 3-8 and 10, which also satisfied requirement (h), had good durability. Requirement (h): The stress relaxation rate is 15% or less. Among Experimental Examples 3-10, Experimental Examples 4-7 and 10 also satisfied the following requirement (i): Experimental Examples 4-7 and 10, which also satisfied requirement (i), had good durability. Requirement (i): The hysteresis loss rate measured in accordance with JIS K6400-2 (2012 edition) Method E is 20% or less.

[0082] Experimental Example 5 with an isocyanate index of 105, Experimental Example 3 with an isocyanate index of 85, and Experimental Example 10 with an isocyanate index of 95 are compared. Experimental Examples 3 and 10 had smaller compression deflection coefficients than Experimental Example 5, and larger deflection amounts in the high load range (700 N or more and 980 N or less).

[0083] Experimental Example 5, which satisfies requirements (a) and (f), is compared with Experimental Example 1, which satisfies requirement (a) but does not satisfy requirement (f). Experimental Example 5 has a 25% hardness that is about 50 N greater than Experimental Example 1, but its compressive deflection coefficient is smaller than Experimental Example 1, and its deflection amount in the high load range (700 N or more and 980 N or less) is larger.

[0084] Experimental Example 4, which contains 85 parts by mass of polyol (a), Experimental Example 8, which contains 80 parts by mass of polyol (a), and Experimental Example 9, which contains 60 parts by mass of polyol (a), are compared. It was found that as the amount of polyol (a) decreases, the compression deflection coefficient increases and the deflection amount in the high load range (700 N or more and 980 N or less) decreases.

[0085] 6. Effects of the Example According to the above-described embodiment, a seat pad with excellent riding comfort can be provided.

[0086] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the present disclosure. [Explanation of symbols]

[0087] 10,110…Seat pad 10A…Surface 10B…Back side 11…1st layer 12…Second layer 13…Third layer 14…4th layer 15…5th layer

Claims

1. A seat pad made of polyurethane foam obtained from a composition containing a polyol and an isocyanate, A seat pad having a compression deflection coefficient of 2.8 or less as measured in accordance with JIS K6400-2 (2012 edition) Method E.

2. A seat pad made of polyurethane foam obtained from a composition containing a polyol and an isocyanate, The polyol includes a polyol having an ethylene oxide unit content of 50 mol% or more when the total amount of alkylene oxide units is taken as 100 mol%, The space between the front surface and the back surface is divided into five equal parts in the thickness direction, and the first, second, third, fourth and fifth layers are defined in this order from the front surface side, The Asker F hardness of the third layer measured from the surface side is set to F3, When the Asker F hardness measured from the surface side of the first layer is F1, F1 / F3<1.0 Meet the seat pad.

3. 0.30≦F1 / F3≦0.70 The seat pad according to claim 2, wherein the above formula (1) is satisfied.

4. The seat pad according to claim 2 or 3, wherein the isocyanate includes carbodiimide-modified diphenylmethane diisocyanate.

5. The seat pad according to any one of claims 2 to 4, wherein the compression deflection coefficient measured in accordance with JIS K6400-2 (2012 edition) E method is 2.8 or less.

6. The seat pad according to any one of claims 2 to 5, wherein the rebound resilience measured in accordance with JIS K6400-3 (2011 edition) is 55% or less.

7. The seat pad according to any one of claims 2 to 6, wherein the stress relaxation rate is 15% or less.

8. The seat pad according to any one of claims 2 to 7, wherein the hysteresis loss rate measured in accordance with JIS K6400-2 (2012 edition) Method E is 20% or less.

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