JP2005124744A - Seat cushion pad and seat for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seat cushion pad and a seat for a vehicle exhibiting excellent cushion feeling and durability and also excellent vibration absorptivity of a high frequency range around 6 Hz although the seat cushion pad is thinned. <P>SOLUTION: The seat cushion pad is composed of polyurethane foam the raw materials of which are: 30 to 80 pts.wt. polyether polyol whose hydroxyl value is 20 to 40 mgKOH/g and which is terminated with an ethylene oxide unit; 70 to 20 pts.wt. polymer polyol whose hydroxyl value is 15 to 30 mgKOH/g; a specified silicone foam stabilizer; a foaming agent; and a polyisocyanate compound in which TDI:MDI=70:30 to 90:10. The thickness of a sitting part is 30 to 50 mm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  In general, a seat cushion pad (hereinafter, simply referred to as a pad or a cushion pad) made of a flexible polyurethane foam having a high cushioning property is used for an automobile seat, and this is placed on a support frame, It is configured as a vehicle seat by covering the pad surface with an epidermis.

  In such a vehicle seat, it is required to lower the vehicle height due to demands for improving the fuel efficiency due to the design of the body and the reduction of the air resistance value. For this reason, the cushion pad may be required to be thinner. In addition, recently, due to the diversification of prime movers and fuels and the demand for expanding the luggage space, the fuel tank can be placed under the seat. In order to improve the storability, it is required to make the cushion pad thinner.

  However, generally, when the seat cushion pad is thinned, the cushion feeling (stroke amount) is lowered particularly when the amount of flexure in the high load region is reduced, and in the case of being noticeable, a feeling of bottoming may occur. In addition, regarding the vibration transmissibility characteristics defined in JASO B-407, the resonance absorption shifts to the high frequency side, so that the vibration absorbability particularly in the high frequency region around 6 Hz is deteriorated. Furthermore, the seat cushion pad is easily sag by thinning, and the durability is deteriorated.

  By the way, Patent Document 1 discloses a seat cushion pad made of a polyurethane foam having a skin layer and a core layer formed by injecting a polyurethane foam raw material into a mold, and has an air permeability of 0.05 to 1.5 cfm. The core layer has a hysteresis loss of 17% or less, the polyurethane foam raw material has a hydroxyl value of 20 to 40 mg KOH / g as a polyol component, 30 to 80 parts by weight of a polyether polyol having a terminal ethylene oxide unit, and a hydroxyl value of 15 to 30 mg KOH / g polymer polyol 70 to 20 parts by weight, silicon foam stabilizer, foaming agent, and polyisocyanate compound of TDI / MDI = 70/30 to 90/10 are used as constituent raw materials. Seat cushion pad made of polydimethylsiloxane or other foaming agent De has been disclosed.

  Patent Document 2 discloses a seat structure including a seat cushion pad made of polyurethane foam and a support frame having a spring, before the support frame is arranged at the lower part on the front side of the seat surface portion of the seat cushion pad. The polyurethane foam raw material constituting the seat cushion pad has a hydroxyl value as a polyol component, comprising an edge portion and elastic means connected to the front edge portion and extending from the front edge portion toward the rear side. 20 to 40 mg KOH / g, polyether polyol having an ethylene oxide unit at the end of 60 to 80 parts by weight, polymer polyol having a hydroxyl value of 15 to 30 mg KOH / g at 40 to 20 parts by weight, a silicone foam stabilizer, a foaming agent, and a polyisocyanate Disclosed using diphenylmethane diisocyanate as a compound It has been.

The seat cushion pads disclosed in these patent documents have a seating portion having a thickness in the range of 60 to 140 mm, and do not correspond to the above-described request for thinning. In other words, conventionally, this type of seat cushion pad has a seating portion thickness of at least 60 mm or more, and there has never been a seat cushion pad having a thin and excellent characteristic as provided by the present invention. Is the actual situation.
Japanese Patent No. 3181279 JP 2002-253381 A

  The present invention has been made in view of the above points, and is a sheet that is excellent in cushioning and durability, and excellent in vibration absorption in a high frequency range of about 6 Hz, although the seat cushion pad is thinned. An object is to provide a cushion pad and a vehicle seat.

式中、Ｘは炭素数１〜４の有機残基であり、Ｒはアルキル基又はアシル基であり、共重合ポリエーテルにおけるエチレンオキサイド単位ｍとプロピレンオキサイド単位ｎの当量比ｍ／ｎが０．４／０．６〜０．０５／０．９５である。 The seat cushion pad of the present invention is a seat cushion pad comprising a polyurethane foam having a skin layer and a core layer formed by injecting a polyurethane foam raw material into a mold, and the polyurethane foam raw material comprises a polyol compound, silicon A foam stabilizer, a foaming agent, and a polyisocyanate compound are used as constituent raw materials. The polyol compound has a hydroxyl value of 20 to 40 mg KOH / g and a polyether polyol of 30 to 80 parts by weight having an ethylene oxide unit at the end. And 70 to 20 parts by weight of a polymer polyol having a hydroxyl value of 15 to 30 mgKOH / g, and the silicon foam stabilizer is polydimethylsiloxane or a compound represented by the following general formula (1), the polyisocyanate compound TDI: MDI = 70 30 to 90: A 10 (weight ratio), in which the thickness of the seat is characterized in that it is a 30 to 50 mm.

In the formula, X is an organic residue having 1 to 4 carbon atoms, R is an alkyl group or an acyl group, and the equivalent ratio m / n of the ethylene oxide unit m to the propylene oxide unit n in the copolymer polyether is 0.00. 4 / 0.6 to 0.05 / 0.95.

  Combining this specific polyurethane foam raw material with a pad configuration with a seating portion thickness of 50 mm or less suppresses a reduction in the feeling of stroke when seated, and reduces the feeling of sag when traveling for a long time. Generation | occurrence | production can be reduced and also the deterioration of the vibrational absorbability in a high frequency range can be suppressed, Therefore Therefore, the thinned seat cushion pad with the outstanding characteristic can be obtained.

In the seat cushion pad of the present invention, the core density is preferably 80 kg / m ³ or more. By increasing the density of the seat cushion pad, the present inventor can reduce the resonance magnification without shifting the resonance point to the high frequency side, and thereby the vibration in the high frequency region around 6 Hz, which is deteriorated by thinning. It has been found that the absorbability can be further improved. That is, by setting the core density of the seat cushion pad to 80 kg / m ³ or more, it is possible to further improve the ride comfort by reducing the vibration transmissibility of around 6 Hz. Further, the durability can be further improved by increasing the density.

  A vehicle seat according to the present invention includes the seat cushion pad and a support frame that is disposed below the seat cushion pad and supports the seat cushion pad, and the support frame elastically seats a seating portion of the seat cushion pad. It is characterized by comprising a spring for supporting the structure.

  As described above, by using a support frame that supports the seat cushion pad and having a spring that elastically supports the seating portion, it is possible to suppress a decrease in cushioning feeling when sitting due to the thin pad. , Can improve sitting comfort. That is, in recent years, a so-called full-form type seat structure in which a support frame without a spring is used and the cushioning property is secured only by the elasticity of the seat cushion pad has become mainstream. Then, it is difficult to cope with the decrease in cushion feeling due to the thinning of the pad. Therefore, the use of such a support frame with a spring is effective.

  In the vehicle seat of the present invention, the support frame includes a front receiving surface portion that receives the lower surface of the front portion of the seat cushion pad, a side wall portion that extends rearward from both left and right ends, and rear end portions of the side wall portions. A connecting portion to be connected; and an S-shaped spring that is bridged between the front receiving surface portion and the connecting portion and elastically supports a seating portion of the seat cushion pad. A steel wire that extends in the front-rear direction while swinging alternately left and right in a horizontal plane, and is provided in a plurality in spaced intervals in the seat width direction, and extends in the front-rear direction passing through the middle between adjacent S-shaped springs Is preferably provided so as to have a line-symmetric relationship with respect to.

  The seat cushion pad is supported by supporting the seat cushion pad by the support frame including the front receiving surface portion having rigidity for receiving the front portion of the seat cushion pad and the S-shaped spring for elastically supporting the seat portion of the pad. A feeling can be heightened. Further, by configuring the S-shaped spring as described above, the load of the seated person transmitted through the seat cushion pad can be received in a well-balanced manner, which is particularly advantageous for supporting a thin pad.

  According to the present invention, a thin seat cushion pad having excellent cushion feeling and durability and excellent vibration absorption in a high frequency range of about 6 Hz can be obtained. Therefore, it becomes possible to cope with the thinning of the seat cushion pad, which is increasingly required in the future, without impairing the sitting comfort and the riding comfort.

  Hereinafter, embodiments of the present invention will be described in detail.

  The vehicle seat according to the embodiment is an automobile seat used for an automobile seat, and is a seat cushion pad 1 made of a polyurethane foam having a skin layer and a core layer formed by injecting a polyurethane foam material into a mold. 1), and a metal support frame 2 (see FIG. 2) that is disposed below the seat cushion pad 1 and supports the seat cushion pad 1.

  As shown in FIG. 1, the seat cushion pad 1 includes a seating portion 11 at the center in the width direction and side portions 12 and 12 formed in a protruding shape on both the left and right sides thereof. 11 and a pair of left and right vertical grooves 13 extending in the front-rear direction along the boundary between the side portions 12 and the left-right vertical grooves 13, 13 are connected in the left-right direction so as to connect the center portions in the front-rear direction. An extending lateral groove 14 is provided, and as a result, a groove is formed in a substantially H shape on the entire top surface of the pad. Then, the seating portion 11 is divided forward and backward by the lateral groove 14, and the front side of the lateral groove 14 receives and supports the thigh of the seated person, and the rear side of the lateral groove 14 receives and supports the seated person's buttocks. It is 16.

  The seat cushion pad 1 has a seating portion 11, more specifically, a hip point 17 of the hip receiving portion 16 (a point corresponding to the center of rotation of the torso and thigh of a human mannequin when seated on a seat according to JASO Z-221) ) Is set to 50 mm or less. The pad thickness T is more preferably set to 45 mm or less. The lower limit of the pad thickness T is preferably 30 mm or more.

The seat cushion pad 1 has a core density (density measured for the core layer) set to 80 kg / m ³ or more. By increasing the core density in this way, the seating part 11 has a thickness as thin as 50 mm or less, and the vibration transmissibility around 6 Hz is lowered to improve the riding comfort, as will be described later in the examples. Can do. The core density is more preferably 90 kg / m ³ or more. The upper limit of the core density is preferably 110 kg / m ³ or less. In general, between the skin layer and the core layer in the seat cushion pad is continuously changed, and the boundary is not clearly formed, but the core density is clearly taken out from the portion that is the core layer. taking measurement.

Further, the seat cushion pad 1 preferably has a 25% hardness of 250 N or more. The 25% hardness (25% ILD) is a load when the seat portion 11, more specifically, the hip point 17 of the buttocks receiving portion 16 is compressed by 25% with a pressure plate having a diameter of 200 mm (conforming to JIS K6400). By setting the 25% hardness within the above range, a comfortable seat with no feeling of bottoming and a good cushion feeling can be obtained. In addition, it is preferable that the minimum of 25% hardness is 320 N or less. 25% hardness, differ in their optimum values depending on the core density, it is preferably, 270～320N the core density is 90~100kg / ^{m 3} core density is 250~300N In 80~90kg / ^{m 3} It is preferable.

The seat cushion pad 1 has an air permeability in the range of 0.05 to 1.5 cfm (cubic feet / min., That is, ft ³ / min) [1.41 to 42.2 L / min], and the core It is preferable that the hysteresis loss of the layer is 17% or less. More preferably, the air permeability is 0.1 to 1.5 cfm [2.81 to 42.2 L / min. And the hysteresis loss of the core layer is 15% or less. By setting the air permeability within the above range, the resonance magnification in the vibration transmissibility characteristic curve can be reduced, and by setting the hysteresis loss of the core layer within the above range, the resonance frequency can be reduced.

  The polyurethane foam constituting the seat cushion pad 1 is a flexible polyurethane foam formed from a polyurethane foam raw material containing at least a polyol compound, a polyisocyanate compound, a foaming agent and a silicon foam stabilizer.

  In the present invention, polyether polyol and polymer polyol are used in combination as the polyol compound.

  The polyether polyol is a polyol obtained by adding an alkylene oxide to a polyfunctional alcohol compound as an initiator. In the present invention, the hydroxyl value is 20 to 40 mgKOH / g, and the terminal is an ethylene oxide unit. A polyether polyol is used.

  Examples of the polyfunctional alcohol compounds include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose, triethanolamine, diethanolamine, and compounds obtained by adding a small amount of alkylene oxide to these. It is done. Examples of the alkylene oxide that undergoes addition polymerization to the polyfunctional alcohol compound include those having 2 or more carbon atoms, such as ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, and 2,3-butylene. Oxide, styrene oxide and the like. Among these alkylene oxides, those in which ethylene oxide and propylene oxide and / or butylene oxide are used in combination are preferable. In particular, those containing an ethylene oxide unit in which ethylene oxide is a ring-opening unit in an addition ratio of 3 to 50% by weight, more preferably 3 to 25% by weight are preferable.

The polyether polyol may be either a random polymer or a block polymer of the alkylene oxide, but the one containing an ethylene oxide unit (— (CH ₂ CH ₂ O) _n H) at the terminal is a reaction with an isocyanate group. It is preferable because of its good properties. The terminal primary conversion rate (terminal ethylene oxide unitization rate) is preferably 3% by weight or more of the oxyalkylene unit of the polyether polyol, more preferably 5% by weight or more, and still more preferably 10 to 20% by weight. is there.

  The polymer polyol is obtained by dispersing polymer particles in the form of fine particles in a polyol compound. In the present invention, a polymer polyol having a hydroxyl value of 15 to 30 mgKOH / g is used.

  Examples of the polymer particles include particles such as addition polymerization polymers such as homopolymers or copolymers of vinyl monomers such as acrylonitrile, styrene, alkyl methacrylate, and alkyl acrylate, and condensation polymerization polymers such as polyester, polyurea, and melamine resin. Can be mentioned. Of these, acrylonitrile and styrene homopolymers or copolymers are preferred. The method of introducing the polymer particles into the polyol compound is not particularly limited. For example, when the polymer particles are an addition polymerization polymer, in the polyol such as polyoxyalkylene polyol, in the presence of a radical polymerization initiator, By polymerizing vinyl monomers such as styrene and acrylonitrile, it can be stably dispersed in the polyol compound.

  In order to ensure durability, both the polyether polyol and the polyoxyalkylene polyol constituting the polymer polyol preferably have a low terminal unsaturated group concentration. Specifically, the terminal unsaturated group concentration is 0. It is preferably 1 meq / g or less.

  The above polyether polyol and polymer polyol are blended in an amount of 30 to 80 parts by weight of polyether polyol and 70 to 20 parts by weight of polymer polyol, based on 100 parts by weight of the entire polyol compound. More preferably, 50 to 70 parts by weight of polyether polyol and 50 to 30 parts by weight of polymer polyol are blended.

  As said polyisocyanate compound, toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) are used together within the range of TDI: MDI = 70: 30-90: 10 by weight ratio.

  Here, diphenylmethane diisocyanate includes purified diphenylmethane diisocyanate (p-MDI) and crude MDI (c-MDI). Moreover, although toluene diisocyanate has a 2, 4- substituted body and a 2, 6-substituted body, use of these mixtures is preferable, and a 2, 4- substituted body / 2, 6-substituted body mixing ratio is 90 /. The use of a 10-60 / 40 mixture is preferred.

  Examples of the blowing agent include water, halogenated hydrocarbons such as HCFC-141b, HFC-134a, HFC-245fa, and HFC-365mfc, low-boiling aliphatic or alicyclic hydrocarbons such as cyclopentane and n-pentane, and liquefaction. Examples include carbon dioxide gas. Among these foaming agents, it is preferable to use water alone.

  As the silicon foam stabilizer, polydimethylsiloxane or a compound represented by the above general formula (1) is used. Since these foam stabilizers have high activity and can make the bubble (cell) diameter of the polyurethane foam fine, the air permeability can be lowered and the resonance magnification can be lowered.

In the above general formula (1), the equivalent ratio a / b between the dimethylsiloxane repeating unit a and the copolymerized polyether-substituted dimethylsiloxane repeating unit b is 0.75 / 0.25 ≦ a / b <1.00. Is preferred. In the formula, a / b and m / n can be measured by NMR. In this measurement, for example, a / b is obtained from the integrated value of the peak intensity based on H of Si—CH ₃ and the integrated value of the peak intensity of H of the methylene group of Si—CH ₂ —, and the ethylene oxide (EO) M / n is determined from the integrated values of the peak intensities of H of the methylene group and H of the methyl group of propylene oxide (PO).

  As such highly active silicon foam stabilizers, SF2965, SF2962 (manufactured by Toray Dow Corning Silicone), L-5366, L-5309 (manufactured by Nihon Unicar) and the like are commercially available and can be exemplified as suitable ones. it can.

  The polyurethane foam raw material is further mixed with a urethanization catalyst. Urethane catalysts include triethylenediamine (TEDA), bis (N, N-dimethylamino-2-ethyl) ether, N, N, N ', N'-tetramethylhexamethylenediamine, bis (2-dimethylaminoethyl). ) Amine-based catalysts such as ether (TOYOCAT-ET; manufactured by Tosoh Corporation), carboxylic acid metal salts such as potassium acetate and potassium octylate, and organometallic compounds such as dibutyltin dilaurate. Among these, the use of an amine catalyst is preferable because it is suitable for the production of water-foamed polyurethane foam.

  In addition to the above components, the polyurethane foam raw materials include low molecular weight crosslinking agents, emulsifiers, antioxidants, UV absorbers, anti-aging agents, fillers, flame retardants, plasticizers, colorants, antifungal and antibacterial agents, etc. These various additives can be added as necessary.

  Low molecular weight cross-linking agents include ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin and other polyhydric alcohols, and polymerization of ethylene oxide and propylene oxide using these polyhydric alcohols as initiators. Examples thereof include compounds having a hydroxyl value of 300 to 1000 mg KOH / g, alkanolamines such as monoethanolamine, diethanolamine, triethanolamine and N-methyldiethanolamine.

  The amount of each component in the polyurethane foam raw material used is the equivalent ratio of the hydroxyl group of the polyol component (calculated including water if water is used as the blowing agent) and the equivalent ratio of the isocyanate group of the polyisocyanate component (isocyanate index [NCO index]) is preferably in the range of 0.85 to 1.15 (85 to 115 according to the index display), more preferably 0.95 to 1.05.

  Moreover, when using water as a foaming agent, the usage-amount of water is 0.1-8 weight part normally with respect to 100 weight part of polyol compounds, and 1.0-1.0 in order to set a core density in the said range. The amount is preferably 2.0 parts by weight. In addition, the usage-amount of a catalyst is 10 weight part or less normally with respect to 100 weight part of polyol compounds, Preferably it is 0.05-1.0 weight part. The amount of the foam stabilizer used is usually 0.01 to 5 parts by weight (based on the active ingredient in the case of a foam stabilizer diluted with a plasticizer or the like) with respect to 100 parts by weight of the polyol compound, preferably 0. .1 to 2 parts by weight.

  The polyurethane foam raw material containing each component described above is molded into a seat cushion pad in a predetermined mold corresponding to various shapes depending on the application to which the seat cushion pad is applied. Usable means can be used as the molding method.

  As shown in FIG. 3, a reinforcing cloth 18 is laminated on the back surface of the seat cushion pad 1. The reinforcing cloth 18 is, for example, an integral molding method in which a supporter (reinforcing material) such as a resin support made of polyurethane, polypropylene, polyethylene, polystyrene, or a foam thereof, or a PP cloth, a coarse blanket, or a non-woven fabric is inserted in a mold in advance. Or it can be laminated by adhesion after foam molding.

  As shown in FIGS. 2 and 3, the support frame 2 has a substantially rectangular shape corresponding to the lower surface portion of the seat cushion pad 1. Specifically, the front receiving surface portion 21 having a substantially horizontal surface extending in the left-right direction that receives the lower surface of the front portion (thigh receiving portion 15) of the seat cushion pad 1 and side wall portions 22, 22 extending rearward from both left and right ends thereof. And the connecting rod 23 which is a connecting portion for connecting the rear end portions of the side wall portions 22 and 22, and the front receiving surface portion 21 and the connecting rod 23 are stretched between the seat cushion pad 1 elastically. And an S-shaped spring 24 for supporting the structure.

  The S-shaped spring 24 is made of a steel wire, and has a front end portion fixed to the rear edge of the front receiving surface portion 21 and a rear end portion fixed to the connecting rod 23. The straight portion 24a and the bent portion 24b are combined. It is formed to extend in the front-rear direction while swinging alternately left and right within a substantially horizontal plane. A plurality of S-shaped springs 24 (four in this embodiment) are provided side by side with a predetermined interval in the sheet width direction. The plurality of S-shaped springs 24 are arranged on substantially the same plane (substantially horizontal plane), and the adjacent springs 24, 24 are provided so as to have a line-symmetric relationship with respect to a line 25 extending in the front-rear direction passing through the middle. It has been. By configuring the S-shaped spring 24 in this way, the load on the seated person transmitted through the seat cushion pad 1 can be received in a balanced manner, which is particularly advantageous for supporting thin pads.

  Further, the four S-shaped springs 24 are provided with reinforcing members 26 so as to cover all of them. The reinforcing member 26 is formed by forming a steel wire into a substantially rectangular closed shape, and is fixed onto the four S-shaped springs 24 by welding or the like.

  When the vehicle seat having the above-described configuration is actually mounted on the vehicle, the seat cushion pad 1 is covered with an outer skin such as a main skin, a moquette, a tricot, a jersey, and a fabric, and a support frame 2 is attached. Provided for assembly.

  Examples will be described below. In addition, the evaluation methods, such as a physical property in an Example, are as follows.

[Physical properties of seat cushion pads]
a) Core density (kg / m ³ ): This is the density measured for the core part of the seat cushion pad. A test piece excluding the skin layer was cut out from the center part of the pad, and the density was measured.

b) 25% hardness (N): a load when the seat cushion pad is compressed 25% with a pressure plate having a diameter of 200 mm (according to JIS K6400). The measurement position was the hip point 17 (see FIGS. 1 and 3).

c) Air permeability (cfm): Measured according to ASTM D-1564. That is, 50 mm in length, 50 mm in width, and 25 mm in thickness including the skin part under the hip point, which is the seating surface of the seat cushion pad, are collected from three locations, and a measuring instrument made by FLUID DATA is used. It is a measured value (DOW method).

d) Hysteresis loss (%) of the core layer: A measurement sample having a length of 100 mm, a width of 100 mm, and a thickness of 30 mm was taken from the core layer (excluding the skin layer) of the seat cushion pad, and in accordance with JIS K-6400. It was measured. The removed skin layer is about 10 mm.

[Static deflection characteristics of seat cushion pads]
e) Using a circular pressure plate with a diameter of 200 mm, compress to 75% of the initial thickness at a speed of 50 mm / min, measure the deflection-load relationship at that time, hysteresis loss, deflection amount at 196 N and spring A constant, a deflection amount at 392 N, and a spring constant were obtained. For the measurement, a deflection tester made by Ueshima was used.

[Durability of seat cushion pad]
d) Hardness reduction rate (%): Using a disk pressure plate with a diameter of 200 mm, pressurize until the stress during pad compression is 245 N, stop the pressure plate there, measure the stress after 10 minutes, and relax The rate was determined.

f) Moist heat compression set (%): A test piece having a length of 50 × width of 50 × thickness of 30 mm was compression-fixed to 50% of the thickness of the test piece with a metal compression plate, and the temperature was 50 ° C. and the humidity was 95%. It was left in a thermostatic bath for 22 hours. Thereafter, the test piece was removed from the compression plate, the thickness was measured after being left for 30 minutes, and the rate of thickness reduction was calculated to obtain wet heat compression set.

[Dynamic characteristics of seat cushion pads]
g) Free vibration: A 50 kg iron-steel-type pressure plate is dropped on the test piece from 0 mm in height, and its attenuation waveform is measured to determine the repulsion rate, logarithmic attenuation rate, stroke amount I, and stroke amount II. Asked. Here, the stroke amount I is the maximum deflection amount during free vibration, and the stroke amount II is the difference between the maximum deflection amount and the deflection amount after vibration attenuation.

h) Forced vibration: According to JASO B-407, a resonance frequency (Hz) is obtained from a vibration transmissibility curve obtained by loading a 50 kg iron-steel pressure plate and performing a forced vibration test with an amplitude of ± 2.5 mm. ), Resonance magnification, and vibration transmissibility at 6 Hz were measured. For measurement of vibration characteristics, a seat cushion vibration tester C-1002DL (manufactured by Ito Seiki Co., Ltd.) was used.

表中の各原料成分の詳細は以下の通りである。 (Test Example 1, Comparative Test Examples 1-3)
Each component shown in Table 1 below is blended in a conventional manner at a weight ratio shown in the same table, and mixed uniformly, then poured into a mold, foamed and cured, and the length x width is 400 x 400 mm and the thickness is Pads as three types of test pieces of 100 mm, 70 mm, and 50 mm were produced.

The detail of each raw material component in a table | surface is as follows.

EP901: polyether polyol manufactured by Mitsui Takeda Chemical Co., whose terminal is an ethylene oxide unit (hydroxyl value = 24 mgKOH / g, terminal unsaturated group concentration <0.1 meq / g)
EP3033: polyether polyol manufactured by Mitsui Takeda Chemical Co. (hydroxyl value = 34 mgKOH / g)
HF-3014: polyether polyol manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (hydroxyl value = 56 mgKOH / g)
POP3690: Polymer polyol manufactured by Mitsui Takeda Chemical Co. (hydroxyl value = 21 mgKOH / g)
POP3628: Polymer polyol manufactured by Mitsui Takeda Chemical Co. (hydroxyl value = 26 mgKOH / g)
P550: Meisei Chemical Co., Ltd. crosslinker SF2962: Toray Dow Corning Silicon Co., Ltd. silicon-based foam stabilizer (represented by the general formula (1), a = 0.77, b = 0.23, m = 0.19, n = 0.81)
SRX274C: Silicon-based foam stabilizer manufactured by Toray Dow Corning Silicon Co. (compound in general formula (1) where a = 0.76, b = 0.24, m = 0.91, n = 0.09)
TEDA-L33: tertiary amine catalyst manufactured by Tosoh Corporation Niax A-1: amine catalyst manufactured by Sankyo Air Products Co., Ltd. TM-20: polyisocyanate compound manufactured by Mitsui Takeda Chemical Co., Ltd. (mixed isocyanate of TDI / c-MDI = 80/20) .

In addition, a / b and m / n of the foam stabilizer are values measured using FT-NMR DPX400S (manufactured by BURKER) as the foam stabilizer 2 wt% solution,
a / b = [(P3-1.5 × P5) / 6] / (P5 / 2)
m / n = [(P1-P2-P5) / 4] / (P2 / 3)
I asked for. Here, P1 has the formula (1) -OCH ₂ in the - group, -OCH- group H (3.0~4.0ppm), P2 is C-CH ₃ group of H (around 1.1 ppm) , P3 is the integral value of H (near 0 ppm) of the Si—CH ₃ group, and P5 is the integral value of H (near 0.45 ppm) of the Si—CH ₂ group in the X group.

The obtained seat cushion pad was measured for core density, 25% hardness, air permeability, and hysteresis loss of the core layer, and evaluated for dynamic characteristics and durability. The results are shown in Table 2. FIG. 4 shows the relationship between the pad thickness and the stroke amount II, and FIG. 5 shows the relationship between the pad thickness and the hardness reduction rate. Furthermore, the vibration transmissibility curve in each pad thickness about Test Example 1 and Comparative Test Example 1 is shown in FIG.

  As shown in FIG. 4, in Test Example 1, although the pad thickness is as thin as 50 mm, the stroke amount II of free vibration is large, and it can be seen that a feeling of stroke can be secured. Further, as shown in FIG. 5, in Test Example 1, the hardness reduction rate could be 14% or less while the pad thickness was 50 mm, and the durability could be ensured. Furthermore, as shown in FIG. 6, the prescription of Test Example 1 can shift the resonance frequency to the low frequency side without increasing the resonance magnification compared with the prescription of Comparative Test Example 1, The vibration transmissibility in the frequency range could be reduced. As described above, with the prescription of Test Example 1, it is possible to obtain an excellent cushion feeling and durability, and excellent vibration absorption in a high frequency range of about 6 Hz, although the pad is thinned.

(Example 1 and Comparative Example 1)
Each component was blended according to the blending of Test Example 1 in Table 1 and mixed uniformly, then poured into a mold and foamed and cured to produce a seat cushion pad 1 shown in FIG. At that time, “Toughnel” (weight per unit area: 140 g / m ² ) manufactured by Mitsui Chemicals Co., Ltd. was attached to the upper mold as the reinforcing cloth 18 and foam-molded integrally. The thickness T at the hip point 17 of the pad was 48 mm.

The core density and 25% hardness of the obtained seat cushion pad were measured. And in Example 1, this seat cushion pad 1 was set on the support frame 2 shown in FIG. 2, and the static deflection characteristic was evaluated. On the other hand, in Comparative Example 1, the static deflection characteristics were evaluated using this seat cushion pad alone. The results are shown in Table 3, and the load-deflection curve is shown in FIG.

  As is apparent from Table 3 and FIG. 7, in Example 1 supported by the support frame 2 including the S-shaped spring 24, a sufficient amount of bending can be secured even in a high load region, and the cushion feeling is greatly improved. It had been.

(Examples 2 to 5 and Comparative Example 2)
The components shown in Table 4 below were blended in the usual manner at the weight ratios shown in the same table, mixed uniformly, then poured into a mold and foam-cured, and the sheets of Examples 2 to 5 and Comparative Example 2 Cushion pads 1 (FIG. 1) were produced. At that time, “Toughnel” (weight per unit area: 140 g / m ² ) manufactured by Mitsui Chemicals Co., Ltd. was attached to the upper mold as the reinforcing cloth 18 and foam-molded integrally. In Examples 2 to 5, the thickness T at the hip point 17 of the pad was set to 48 mm. Comparative Example 2 is a control (conventional example), and the thickness T at the hip point is 78 mm.

About each obtained seat cushion pad, the core density and 25% hardness were measured. Further, the seat cushion pad was set on the support frame 2 shown in FIG. 2 to evaluate the dynamic characteristics. The results are shown in Table 4, and the vibration transmissibility curve is shown in FIG.

As is clear from Table 4 and FIG. 8, by increasing the density of the seat cushion pad, the resonance magnification could be lowered while shifting the resonance point to the low frequency side rather than shifting to the high frequency side. . In addition, the vibration transmissibility at 6 Hz also decreased due to the increase in density, and by setting the core density to 80 kg / m ³ or more, the vibration transmissibility at 6 Hz could be made equal to that of Comparative Example 2 with a large pad thickness. . Moreover, the repulsion rate was also reduced by the higher density. It is presumed that the decrease in the repulsion rate and the resonance magnification due to the increase in density is due to the decrease in the air permeability of the pad due to the increase in density.

The wet heat compression set was measured for the seat cushion pad of Example 2 (core density = 60.8 kg / m ³ ) and the seat cushion pad of Example 4 (core density = 80.5 kg / m ³ ). In Example 2, it was 10%, whereas in Example 4, it was 7%, and an improvement in durability was observed.

(Examples 6 and 7)
The components shown in Table 5 below were blended in a conventional manner at the weight ratios shown in the same table, mixed uniformly, then poured into a mold, foamed and cured, and seat cushion pads 1 of Examples 6 and 7 ( 1) were prepared. At that time, “Toughnel” (weight per unit area: 140 g / m ² ) manufactured by Mitsui Chemicals Co., Ltd. was attached to the upper mold as the reinforcing cloth 18 and foam-molded integrally. The thickness T at the hip point 17 of the pad was 40 mm.

About each obtained seat cushion pad, the core density and 25% hardness were measured. Further, the seat cushion pad was set on the support frame 2 shown in FIG. 2 to evaluate the dynamic characteristics. The results are as shown in Table 5. By increasing the density of the seat cushion pad, the resonance magnification could be lowered without shifting the resonance point to the high frequency side, and the vibration transmissibility of 6 Hz could be lowered. .

It is a perspective view which shows an example of the seat cushion pad which comprises the vehicle seat of this invention. It is a perspective view which shows an example of the support frame which comprises the vehicle seat. It is sectional drawing of the vehicle seat. It is a graph which shows the relationship between the pad thickness and stroke amount 2 in Test Example 1 and Comparative Test Examples 1-3. It is a graph which shows the relationship between the pad thickness and the hardness reduction rate in Test Example 1 and Comparative Test Examples 1 to 3. 5 is a graph showing vibration transmissibility curves at each pad thickness for Test Example 1 and Comparative Test Example 1. 5 is a graph showing load-deflection curves in Example 1 and Comparative Example 1. 6 is a graph showing vibration transmissibility curves in Examples 2 to 5 and Comparative Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Seat cushion pad 11 ... Seating part 17 ... Hip point 2 ... Support frame 21 ... Front side receiving surface part 22 ... Side wall part 23 ... Connecting rod (connecting part)
24 …… S-shaped spring 25 …… Line extending in the front-rear direction

Claims (4)

A seat cushion pad comprising a polyurethane foam having a skin layer and a core layer molded by injecting a polyurethane foam raw material into a mold,
The polyurethane foam raw material includes a polyol compound, a silicon foam stabilizer, a foaming agent, and a polyisocyanate compound as constituent raw materials,
The polyol compound is composed of 30 to 80 parts by weight of a polyether polyol having a hydroxyl value of 20 to 40 mgKOH / g, an end having an ethylene oxide unit, and 70 to 20 parts by weight of a polymer polyol having a hydroxyl value of 15 to 30 mgKOH / g. ,
The silicon foam stabilizer is polydimethylsiloxane or a compound represented by the following general formula (1),
The polyisocyanate compound is TDI: MDI = 70: 30 to 90:10 (weight ratio),
A seat cushion pad, wherein the seating portion has a thickness of 30 to 50 mm.

(In the formula, X is an organic residue having 1 to 4 carbon atoms, R is an alkyl group or an acyl group, and the equivalent ratio m / n of ethylene oxide unit m to propylene oxide unit n in the copolymerized polyether is 0. .4 / 0.6 to 0.05 / 0.95) The seat cushion pad according to claim 1, wherein the core density is 80 kg / m ³ or more.   The seat cushion pad according to claim 1 or 2, and a support frame that is disposed below the seat cushion pad and supports the seat cushion pad, wherein the support frame elastically supports a seating portion of the seat cushion pad. A vehicle seat comprising a spring for supporting. The support frame includes a front receiving surface portion that receives the lower surface of the front portion of the seat cushion pad, a side wall portion that extends rearward from both left and right ends, a connecting portion that connects the rear end portions of the side wall portions, and the front receiving portion. An S-shaped spring that is stretched between the surface portion and the connecting portion and elastically supports the seating portion of the seat cushion pad;
The S-shaped springs are made of steel wires extending in the front-rear direction while swinging left and right alternately in a substantially horizontal plane, and a plurality of S-shaped springs are provided at intervals in the sheet width direction, and between the adjacent S-shaped springs. The vehicle seat according to claim 3, wherein the vehicle seat is provided so as to have a line-symmetric relationship with respect to a line extending in the front-rear direction passing through the middle.

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