JP4926599B2 - Seat cushion - Google Patents

Description

  The present invention relates to a seat cushion having a soft surface and a reduced bottom feeling in a vehicle seat such as an automobile.

  In automobiles, vibration transmission prevention means such as suspension systems and engine mounts that absorb engine vibrations are provided to reduce transmission of vibrations due to vehicle running, engine vibrations, etc., and to ensure passenger comfort. ing. Furthermore, a soft polyurethane foam is used as a seat cushion because it requires a good feel when seated. This type of flexible polyurethane foam has high cushioning properties and excellent seating feeling.

By the way, there are various types of automobiles such as passenger cars and trucks, and passenger cars also include types of ordinary passenger cars, sports cars, wagon cars and the like. And according to those kinds, the device which gives a passenger | crew comfort about a seat cushion is given. For example, a seat cushion pad in which a flexible polyurethane foam sheet is laminated with a thin layer material as an intermediate layer on a seat surface portion of a molded polyurethane foam pad is known (see, for example, Patent Document 1). The purpose of this seat cushion pad is to be able to finely adjust static characteristics such as hardness and impact resilience and dynamic characteristics such as vibration absorption characteristics by a simple method.
JP 2002-306274 A (pages 2 to 4)

However, in the conventional seat cushion pad described in Patent Document 1, a flexible polyurethane foam sheet is laminated on the rear portion of the seat surface or the entire seat surface in order to adjust the physical characteristics for improving the sitting comfort. ing. Specifically, the hardness of the seat cushion pad is 20 kgf / 314 cm ² , and the hardness of the slab sheet (soft polyurethane foam sheet) is 11 kgf / 314 cm ² (Example of page 5 of Patent Document 1). In this case, both the seat cushion pad and the slab seat are set to have low hardness. For this reason, the entire seating surface is softened, and when the user sits down, the seat surface sinks and a feeling of bottoming is felt, and the feeling is poor.

  Moreover, a thermoplastic polyurethane film as a thin layer material is interposed between the polyurethane foam pad and the flexible polyurethane foam sheet, in particular, in order to improve vibration absorption characteristics. Since the thermoplastic polyurethane film of such a thin layer material is harder than the foam, it gives a hard feel when seated, and increases the feeling of bottoming. Therefore, there is a need for a seat cushion that retains the softness of the surface while suppressing the feeling of bottoming.

  Accordingly, an object of the present invention is to provide a seat cushion having a good surface softness and a reduced feeling of bottoming.

In order to achieve the above object, the seat cushion of the invention according to claim 1 is laminated by adhering two upper and lower layers formed by molding a two types of soft polyurethane foams having different hardnesses with an adhesive. Formed, the upper layer has a hardness of 150 to 190 N, the lower layer has a hardness of 280 to 320 N, the total thickness is 60 to 135 mm, and the upper layer has a thickness of 10 to 10 of the total thickness. 45%, which is set to be thinner than the thickness of the lower layer 14, the bottoming index represented by the following formula is 0.48 to 0.55, and the amount of deflection when a load of 100 N is applied is 4 to 4%. It is characterized by being 6 mm.

Bottom index = [Bending amount when a load of 1000 N is applied (mm) −Bending amount when a load of 500 N is applied (mm)] / Bending amount when a load of 500 N is applied (mm 2 )

According to the present invention, the following effects can be exhibited.
In the seat cushion of the invention according to claim 1, the bottom index of the flexible polyurethane foam is set to a specific range of 0.48 to 0.55, and the amount of deflection when a load of 100 N is applied is set. It is set to a specific range of 4 to 6 mm. At a low load of 100 N, an appropriate amount of bending of 4 to 6 mm can be obtained, so that a soft feeling is given. In addition, the bottoming index indicates the ratio of the amount of bending by subtracting the amount of bending due to low load from the amount of bending due to high load to the amount of bending due to low load. By setting a narrow range, sinking can be suppressed even under heavy loads.

Therefore, the soft feeling on the surface of the seat cushion is good and the feeling of bottoming can be reduced.
In addition , the upper and lower two layers obtained by molding two types of soft polyurethane foams having different hardnesses by a molding method are bonded and formed by an adhesive . Since the hardness of the upper layer is 150 to 190 N and the hardness of the lower layer is 280 to 320 N, the upper layer is soft and the lower layer is formed to be harder than the upper layer so as to support the load. The total thickness of the seat cushion is set to 60 to 135 mm assuming the thickness of the product, and the thickness of the upper layer is set to be 10 to 45% of the total thickness and thinner than the thickness of the lower layer. Yes. Therefore, it is possible to improve the balance between soft feel and bottoming feel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments that are considered to be the best of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1A, a seat cushion 10 according to the present embodiment is used for a seat portion of a vehicle seat such as an automobile, and is a soft polyurethane foam (hereinafter referred to as a polyurethane foam or simply a foam). Say). Here, the soft polyurethane foam is a polyurethane foam having an open-cell structure, flexibility and resilience. FIG. 1A shows only the seat portion of the seat, and the backrest portion is omitted. The center of the seat portion is a seat portion 11 on which the butt is placed, and the side portions 12 on both sides thereof are formed so as to rise more than the seat portion 11. The seat cushion 10 has a bottom index of 0.48 to 0.55 represented by the following formula and a load of 100 N in order to suppress the bottom feeling and improve the softness of the surface. The amount of bending when it is made is 4 to 6 mm.

Bottom index = [Bending amount when a load of 1000 N is applied (mm) −Bending amount when a load of 500 N is applied (mm)] / Bending amount when a load of 500 N is applied (mm)
The bottoming index focuses on the difference between the amount of deflection due to high load and the amount of deflection due to low load, and by setting the ratio of the difference to the amount of deflection due to low load within a certain range, it sinks into the seat cushion 10 when seated. This suppresses the feeling of hitting the bottom. The bottoming index is preferably 0.50 to 0.54. In the bottom index, 1000N can be regarded as a load of a person weighing 100 kg, and 500 N can be regarded as a load of a person weighing 50 kg.

  As shown in FIG. 1 (b), the seat cushion 10 includes an upper layer 13 and a lower layer formed by two types of soft polyurethane foams having different hardnesses in order to achieve both a reduction in the feeling of bottoming and an improvement in the softness of the surface. It is preferable to form a laminate of 14 layers. In this case, the hardness of the upper layer 13 is preferably 150 to 190N, and the hardness of the lower layer 14 is preferably 280 to 320N. Here, the hardness is a value measured according to the method B of JIS K 6400-2: 2004. The upper layer 13 is a portion that directly touches the buttocks when seated, and is set to be softer than the lower layer 14 in order to give a soft feel. On the other hand, the lower layer 14 is set to be harder than the upper layer 13 in order to eliminate the feeling of supporting the load and hitting the bottom.

  When the hardness of the upper layer 13 is less than 150 N, the upper layer 13 becomes too low in hardness and sinks greatly, resulting in a poor feel and a feeling of bottoming. On the other hand, when the hardness of the upper layer 13 exceeds 190 N, it is not preferable because it gives a hard feel when seated and increases discomfort. When the hardness of the lower layer 14 is less than 280 N, the lower layer 14 is soft, and a feeling of bottoming is felt at the time of sitting, which is not preferable. On the other hand, when the hardness of the lower layer 14 exceeds 320 N, the lower layer 14 becomes too hard, and the soft touch tends to be impaired when sitting.

  Further, the total thickness D of the seat cushion 10 is 60 to 135 mm mainly from the product shape, and the thickness D1 of the upper layer 13 is the total thickness in order to maintain a balance between the soft feeling and the bottom feeling of the seat cushion 10. 10 to 45% of the thickness is preferable. When the total thickness D of the seat cushion 10 is less than 60 mm, the feeling at the time of sitting is lowered and the appearance of the seat is also deteriorated. On the other hand, when the total thickness D of the seat cushion 10 exceeds 135 mm, the seat cushion 10 becomes too thick and bulky, which is not preferable because it takes up space. Moreover, when the thickness D1 of the upper layer 13 is less than 10% of the total thickness D, it is difficult to obtain the soft feeling of the seat cushion 10, which is not preferable. On the other hand, when the thickness D1 of the upper layer 13 exceeds 45% of the total thickness D, the thickness of the lower layer 14 becomes relatively thin, and it becomes difficult to suppress the feeling of bottoming.

  The seat cushion 10 is manufactured by, for example, a molding method or a combination of a molding method and a slab molding method. First, when the lower layer 14 is formed by a molding method, a foam raw material for forming the lower layer 14 in the molding recess is heated to 60 to 70 ° C. with a mold having a molding recess (cavity) having the shape of the lower layer 14. Inject, react and foam the foam material. Then, by opening the mold and taking out the foam forming the lower layer 14, the lower layer 14 having a shape as shown in FIG. 2 is obtained. A fitting recess 15 for fitting the upper layer 13 is formed on the upper surface of the lower layer 14.

  On the other hand, the upper layer 13 is formed by a mold forming method or a slab forming method. In the case of the molding method, the upper layer 13 is formed in the same manner as in the case of the lower layer 14 using a mold having a molding recess having the shape of the upper layer 13. In the case of the slab molding method, the foam raw material for forming the upper layer 13 is supplied on the belt conveyor, reacted and foamed at room temperature and atmospheric pressure, molded, and the resulting slab foam is cut into a predetermined shape. A square plate-like upper layer 13 as shown in FIG. 2 is obtained.

As the foam material, those containing polyols, polyisocyanates, foaming agents, catalysts, crosslinking agents and foam stabilizers are used. This foam raw material will be described in order.
As the polyols, polyether polyol, polymer polyol, polyester polyol and the like are used. Polyether polyols include polypropylene glycol and polytetramethylene glycol in addition to compounds obtained by addition polymerization of alkylene oxide to polyhydric alcohols. As the polyhydric alcohol, glycerin, dipropylene glycol, trimethylolpropane and the like are used. As the alkylene oxide, ethylene oxide, propylene oxide or the like is used.

  Specific examples of the polyether polyol include a triol obtained by addition polymerization of glycerin with propylene oxide, a triol obtained by addition polymerization of ethylene oxide, and a diol obtained by addition polymerization of propylene oxide with dipropylene glycol. When addition polymerization of ethylene oxide is performed, the content is about 5 to 15 mol%. When the content of the polyethylene oxide unit is large, the hydrophilicity becomes high, the miscibility with highly polar molecules, polyisocyanates and the like is improved, and the reactivity becomes high.

  The polyether polyol may be a polyether ester polyol. The polyether ester polyol is a compound obtained by reacting a polyoxyalkylene polyol with a polycarboxylic acid anhydride and a compound having a cyclic ether group. Examples of polyoxyalkylene polyols include polyethylene glycol, polypropylene glycol, and propylene oxide adducts of glycerin. Examples of polycarboxylic acid anhydrides include anhydrides such as succinic acid, adipic acid, and phthalic acid. Examples of the compound having a cyclic ether group (alkylene oxide) include ethylene oxide and propylene oxide. The polyether polyol is preferable from the viewpoint that it has excellent reactivity with polyisocyanates and does not hydrolyze as compared with the polyester polyol.

  The polymer polyol is a polyol obtained by graft polymerization of a vinyl monomer to a polyether polyol. The polyether polyol for forming the polymer polyol is obtained by addition polymerization of an alkylene oxide to a polyhydric alcohol. As the polyhydric alcohol, glycerin, dipropylene glycol, trimethylolpropane and the like are used. As the alkylene oxide, ethylene oxide, propylene oxide or the like is used. As the vinyl monomer, acrylonitrile, styrene, methyl methacrylate or the like is used. The content of the vinyl monomer unit (graft portion) in the polymer polyol is preferably 10 to 40% by mass in the total amount with the polyether polyol. In the polymer polyol, the graft portion has a solid content by crystallization.

  Polyester polyols include condensed polyester polyols obtained by reacting polycarboxylic acids such as adipic acid and phthalic acid with polyols such as ethylene glycol, propylene glycol and glycerin, as well as lactone polyester polyols and polycarbonate polyester polyols. Is used.

  The molecular weight, blending amount and the like of the polyols are appropriately set according to a conventional method. Moreover, the polyols can change the functional group number and hydroxyl value of a hydroxyl group by adjusting the kind, molecular weight, polymerization degree, condensation degree, etc. of a raw material component.

  Next, the polyisocyanates to be reacted with the polyols are compounds having a plurality of isocyanate groups, specifically tolylene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), and 1,5-naphthalene. Diisocyanate (NDI), triphenylmethane triisocyanate, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate, isophorone diisocyanate (IPDI), modified products thereof and the like are used.

  The isocyanate index (isocyanate index) of polyisocyanates is most effective for adjusting the hardness of the foam. When the isocyanate index is decreased, the foam tends to become low hardness, and when the isocyanate index is increased, the hardness is increased. Show the tendency to become. For example, in the case of a foam forming the upper layer 13, the isocyanate index is set to 90 to 100, and in the case of a foam forming the lower layer 14, the isocyanate index is set to more than 100 and not more than 110. . Here, the isocyanate index represents the equivalent ratio of isocyanate groups of polyisocyanates to active hydrogen groups such as polyols, water as a foaming agent, cross-linking agent, and foam breaker in percentage. Therefore, an isocyanate index exceeding 100 means that polyisocyanates are in excess of polyols.

  The cross-linking agent has a plurality of hydroxyl groups in one molecule, increases the cross-linking density of the foam, and improves physical properties such as hardness and tensile strength. This crosslinking agent reacts with polyisocyanates to form a crosslinked structure in the foam. Specifically, ethylene glycol, butanediol, hexanediol, diethylene glycol, dipropylene glycol, 2,2-bis (4- Hydroxyphenyl) propane, glycerin, trimethylolpropane, diethanolamine, triethanolamine, pentaerythritol and the like are used. One or more of these crosslinking agents are appropriately selected and used.

  The catalyst is mainly for accelerating the urethanization reaction between polyols and polyisocyanates. Specific examples of the catalyst include tertiary amines such as triethylenediamine, dimethylethanolamine, bis (2-dimethylaminoethyl) ether, N, N ′, N′-trimethylaminoethylpiperazine, and tin octoate (tin octoate). ) And the like, acetates, alkali metal alcoholates and the like are used. One or two or more of these catalysts are appropriately selected and used. The catalyst content is preferably 0.1 to 2.0 parts by mass per 100 parts by mass of polyols. When the catalyst content is less than 0.1 parts by mass, the urethanation reaction or the like is not sufficiently promoted, and when it exceeds 2.0 parts by mass, the urethanation reaction or the like proceeds excessively and the reaction is not successful. It is not preferable because it becomes uniform and side reactions occur.

  The foaming agent is for foaming a polyurethane resin to form a polyurethane foam. For example, pentane, cyclopentane, hexane, cyclohexane, dichloromethane (methylene chloride) and the like are used in addition to water. As the foaming agent, water that is highly reactive in the foaming reaction and easy to handle is preferable. When the blowing agent is water, the content is preferably 1 to 5 parts by mass per 100 parts by mass of polyols. If the water content is less than 1 part by mass, the amount of foaming is small, and the foam tends to have high hardness. If it exceeds 5 parts by mass, the temperature tends to rise during reaction and foaming, and it is difficult to control it. Absent.

  The foam stabilizer is for smoothly progressing foaming by the foaming agent, and those generally used in the production of foams can be used. Specific examples of the foam stabilizer include silicone compounds such as polydimethylsiloxane, anionic surfactants such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate, polyether siloxane, and phenolic compounds. The content of the foam stabilizer is preferably 0.1 to 1 part by mass per 100 parts by mass of polyols. When this content is less than 0.1 part by mass, the foam regulating action at the time of foaming of the foam material is not sufficiently exhibited, and it becomes difficult to obtain a good foam. On the other hand, when the amount exceeds 1 part by mass, the foam regulating action becomes strong, the cell connectivity tends to be lowered, and the cushion feeling of the foam is lowered.

  In addition to the raw material of the polyurethane foam, a foam breaker, a filler, a colorant, a plasticizer, a flame retardant, a stabilizer, an antioxidant, an ultraviolet absorber, an antiaging agent, and the like are blended as necessary. The foam breaker is a substance that inhibits foam formation during foaming, increases the cell diameter, or communicates the cells to promote the open cell structure of the foam. Specific examples of such foam breakers include silicone compounds, oils such as polybutene, polybutadiene polyols, acidic compounds having a fluoroalkyl group or salts thereof such as polyfluorocarboxylic acid, polyfluorosulfonic acid, Examples thereof include phosphoric acid monoesters of polyfluoroalcohol, phosphoric acid diesters of polyfluoroalcohol, and polyoxyalkylene polyols (highly hydrophilic).

  Then, the foam raw material is reacted to be foamed and cured to produce a soft polyurethane foam, but the reaction at that time is complicated, and basically the following reaction is the main component. . That is, addition polymerization reaction (polyurethanization reaction, resinification reaction) between polyols and polyisocyanates, foaming (foaming) reaction between polyisocyanates and water as a blowing agent, and further, these reaction products and polyisocyanates. This is a crosslinking (curing) reaction with isocyanates. When producing a foam, a one-shot method in which a polyol and a polyisocyanate are directly reacted, or a polyol and a polyisocyanate are reacted in advance to obtain a prepolymer having an isocyanate group at a terminal, Any of the prepolymer methods in which polyols are reacted therewith can be employed.

  Now, the operation of the present embodiment will be described. The seat cushion 10 is formed in a two-layer structure by laminating a lower layer 14 and an upper layer 13 of a flexible polyurethane foam by a molding method. The obtained flexible polyurethane foam has a bottoming index set in a specific range of 0.48 to 0.55, so that the amount of flexure can be suppressed even when a high load is applied to the seat cushion 10, and Subduction is suppressed. Furthermore, since the amount of bending when a low load of 100 N is applied to the seat cushion 10 is set to a specific range of 4 to 6 mm, an appropriate amount of bending can be obtained at a low load, and a soft feel can be given.

The effects exhibited by the above embodiment will be described collectively below.
In the seat cushion 10 according to the present embodiment, the bottom index represented by the above formula is 0.48 to 0.55, and the amount of deflection when a load of 100 N is applied is 4 to 6 mm. . For this reason, the hardness and softness of the foam are harmonized, the soft feeling on the surface of the seat cushion 10 is good, the feeling of bottoming can be reduced, the riding comfort is improved, and the vehicle is used for vehicles such as automobiles. Suitable as a sheet material.

  -By stacking and forming the seat cushion 10 in two upper and lower layers with two types of soft polyurethane foams having different hardness, the upper layer 13 has a hardness of 150 to 190 N, and the lower layer 14 has a hardness of 280 to 320 N. The upper layer 13 is soft and the lower layer 14 is harder than the upper layer 13 so as to support the load. Further, the thickness D of the seat cushion 10 is set to 60 to 135 mm assuming the thickness of the product, and the thickness D1 of the upper layer 13 is set to 10 to 45% of the total thickness D of the lower layer 14. By setting the thickness to be thinner than the thickness, the balance between the soft feeling and the bottom feeling of the seat cushion 10 can be improved.

Hereinafter, the embodiment will be described more specifically with reference to reference examples, examples and comparative examples, but the present invention is not limited to these examples.
(Reference Examples 1-9)
First, the flexible polyurethane foam used in each example and each comparative example was molded by a molding method. That is, the mold was heated to 68 ° C., the foam raw material for forming the lower layer 14 was injected into the molding recess, and the foam raw material was reacted and foamed (Reference Examples 5 to 9). Then, after 5 minutes, the mold was opened and the foam forming the lower layer 14 was taken out. Similarly, the upper layer 13 was formed by a molding method (Reference Examples 1 to 4). The compositions of the foam raw materials of Reference Examples 1 to 9 and the hardness of the foam are shown together in Table 1. The amount of each component in Table 1 represents parts by mass.

The foam material used is shown below.
Polyether polyol: A product obtained by addition polymerization of propylene oxide and ethylene oxide to glycerin, molecular weight 7000, number of functional groups 3 regarding hydroxyl group, manufactured by Mitsui Takeda Chemical Co., Ltd., PPG EP-901.

Polymer polyol: molecular weight 4500, functional group number 3, hydroxyl value 25 mgKOH / g, manufactured by Sanyo Chemical Industries, KC401.
Crosslinking agent 1: Glycerin Crosslinking agent 2: Diethanolamine Catalyst 1: Resinization catalyst, a mixture of 30 to 40% by mass of triethylenediamine and 60 to 70% by mass of propylene glycol, LV33, manufactured by Chukyo Yushi Co., Ltd.

  Catalyst 2: Foaming catalyst, a mixture of 70% by mass of bis (2-dimethylaminoethyl) ether and 30% by mass of dipropylene glycol, DABCO BL-11 manufactured by Air Products Co., Ltd.

Foaming agent: water Foam stabilizer: polydimethylsiloxane.
Polyisocyanate: Tolylene diisocyanate (a mixture of 80% by mass of 2,4-tolylene diisocyanate and 20% by mass of 2,6-tolylene diisocyanate), manufactured by Nippon Polyurethane Industry Co., Ltd., T-80

表１に示したように、イソシアネート指数を９２〜１００に設定することにより、発泡体の硬さを１３０〜１９０Ｎにすることができ、イソシアネート指数を１０２〜１０６に設定することにより、発泡体の硬さを２８０〜３８０Ｎにすることができた。
（実施例１〜８及び比較例１〜３）
参考例１〜９で得られた発泡体を下層１４及び上層１３とし、下層１４の嵌合凹所１５に上層１３を嵌合し、それらを接着剤で接着して積層し、２層構造のシートクッション１０を得た。得られた各シートクッション１０について、１００Ｎの荷重を作用させたときの撓み量（ｍｍ）、５００Ｎの荷重を作用させたときの撓み量（ｍｍ）及び１０００Ｎの荷重を作用させたときの撓み量（ｍｍ）を測定し、前述の底つき指数を算出した。また、シートクッション１０に実際に着座し、官能的評価として底つき感、表面ソフト感及び座り心地を下記に示す方法にて測定した。それらの結果を表２に示した。

As shown in Table 1, by setting the isocyanate index to 92-100, the hardness of the foam can be 130-190 N, and by setting the isocyanate index to 102-106, The hardness could be 280-380N.
(Examples 1-8 and Comparative Examples 1-3)
The foams obtained in Reference Examples 1 to 9 are used as the lower layer 14 and the upper layer 13, the upper layer 13 is fitted into the fitting recess 15 of the lower layer 14, and they are adhered and laminated with an adhesive, and have a two-layer structure. A seat cushion 10 was obtained. About each obtained seat cushion 10, the deflection amount (mm) when a load of 100N is applied, the deflection amount (mm) when a load of 500N is applied, and the deflection amount when a load of 1000N is applied (Mm) was measured, and the above-mentioned bottom index was calculated. In addition, the seat cushion 10 was actually seated, and as a sensory evaluation, a feeling of bottoming, a surface soft feeling and a sitting comfort were measured by the following methods. The results are shown in Table 2.

A feeling of bottoming: When sitting on a seat cushion, the feeling of hitting the bottom was evaluated according to the following criteria.
◎: No feeling of hitting the bottom, very good, ○: No feeling of hitting the bottom, good, △: Some feeling of hitting the bottom, uncomfortable, X: Feeling of hitting the bottom, very Uncomfortable.

Surface soft feeling: When seated on the seat cushion 10, the softness of the surface was evaluated according to the following criteria.
◎: surface is soft and feel is very good, ○: surface is soft and feel is good, △: surface is slightly hard and feel is slightly unsatisfactory, ×: surface is hard and unpleasant is there.

Sitting comfort: When sitting on the seat cushion 10, the comfort was evaluated according to the following criteria.
◎: Appropriate hardness and subduction, very good touch, ○: Appropriate hardness and subduction, good touch, Δ: Slightly hard feeling, less subduction, or a little Soft feeling, much sinking and slightly unsatisfactory feel, x: surface is too hard or too soft, unpleasant feeling.

Comprehensive evaluation: Each evaluation of the above-mentioned feeling of bottoming, surface soft feeling and sitting comfort was synthesized and evaluated according to the following criteria from the viewpoint of whether or not the seat cushion 10 is appropriate.
A: Most suitable as a seat cushion, O: Good as a seat cushion, Δ: Unsatisfactory as a seat cushion, ×: Unsuitable as a seat cushion.

  Further, as Comparative Example 1 and Comparative Example 2, when a seat cushion 10 having a single layer (single layer) structure as shown in Table 2 was manufactured, the bottom index was less than 0.48, and a load of 100 N was applied. An example is shown in which the amount of bending is less than 4 mm. As a comparative example 3, a seat cushion 10 having a two-layer structure as shown in Table 2 is manufactured, and the bottoming index exceeds 0.55, and the amount of deflection when a load of 100 N is applied is less than 4 mm. It was.

表２に示した結果より、実施例１〜８においては、底つき指数が０．５０〜０．５４に設定されていると共に、１００Ｎ作用時の撓み量が４．０〜６．０ｍｍに設定されている。このため、底つき感は非常に良好で、表面ソフト感も良好であると同時に、座り心地も良好であり、従って総合評価が非常に良好であった。

From the results shown in Table 2, in Examples 1 to 8, the bottoming index is set to 0.50 to 0.54, and the amount of deflection at the time of 100N action is set to 4.0 to 6.0 mm. Has been. For this reason, the feeling of bottoming was very good, the softness of the surface was also good, and the sitting comfort was also good, so the overall evaluation was very good.

On the other hand, in Comparative Example 1 and Comparative Example 2, the seat cushion 10 having a single layer structure has a bottoming index of less than 0.48, and the amount of deflection when a load of 100 N is applied is less than 4 mm. The soft feeling was poor and the feeling of bottoming was insufficient, and the overall evaluation was lower than in Examples 1-8. In Comparative Example 3, although the seat cushion 10 has a two-layer structure, the bottom index exceeds 0.55, and the amount of deflection when a load of 100 N is applied is less than 4 mm. Was very bad and the overall evaluation was greatly reduced.
(Examples 9-12 and Comparative Examples 4-8)
In order to clarify a preferable range for the hardness of the upper layer 13 and the lower layer 14, in Examples 9 to 12, the hardness of the upper layer 13 is evaluated in combination with the hardness of 150 to 190N and the hardness of the lower layer 14 in the range of 280 to 320N. Went. Of course, the bottoming index was set to 0.50 to 0.52 and the amount of deflection when a load of 100 N was applied was set to 4 to 6 mm in the range of the present invention.

  On the other hand, in Comparative Example 4, the hardness of the upper layer 13 is set low to 130N, the hardness of the lower layer 14 is set high to 330N, and the bottoming index is set low to 0.33, and a load of 100N is applied. The amount of bending at the time was set high to 7 mm. In Comparative Example 5, the hardness of the upper layer 13 was set low to 140 N and the bottoming index was set low to 0.38. In Comparative Example 6, the hardness of the lower layer 14 was set high at 330 N, and the bottoming index was set low at 0.42. Further, in Comparative Example 7, the hardness of the lower layer 14 was set low to 270 N, and the bottoming index was set low to 0.38. In Comparative Example 8, the hardness of the upper layer 13 was set high at 200 N, the bottoming index was set low at 0.47, and the amount of deflection when a load of 100 N was applied was set low at 3 mm.

  And actually sitting to each seat cushion 10 of Examples 9-12 and Comparative Examples 4-8, the sitting comfort regarding a feeling of bottoming and a surface soft feeling was evaluated on the basis of the following criteria. The results are shown in Table 3.

  ○: There was no feeling of hitting the bottom, the surface was soft, and the sitting comfort was good. Δ: Sitting comfort was slightly poor. X: Sitting comfort was poor.

表３に示した結果より、実施例９〜１２においては、底つき指数を０．５０〜０．５２、１００Ｎの荷重を作用させたときの撓み量を４〜６ｍｍという前提の下に、上層１３の硬さが１５０〜１９０Ｎ及び下層１４の硬さが２８０〜３２０Ｎの範囲で良好な座り心地が得られた。従って、上層１３の硬さは１５０〜１９０Ｎ及び下層１４の硬さは２８０〜３２０Ｎが好ましい範囲であった。

From the results shown in Table 3, in Examples 9 to 12, the upper layer is based on the assumption that the bottom index is 0.50 to 0.52 and the amount of deflection when a load of 100 N is applied is 4 to 6 mm. Good seating comfort was obtained when the hardness of 13 was 150 to 190 N and the hardness of the lower layer 14 was 280 to 320 N. Accordingly, the hardness of the upper layer 13 is preferably 150 to 190 N and the hardness of the lower layer 14 is preferably 280 to 320 N.

On the other hand, in Comparative Example 4, the bottoming index is lowered to 0.33, the amount of deflection when a load of 100 N is applied is increased to 7 mm, the hardness of the upper layer 13 is decreased to 130 N, and the lower layer 14 Since the hardness was increased to 330 N, the sitting comfort was insufficient. In Comparative Example 5, the bottoming index was lowered to 0.38, and the hardness of the upper layer 13 was lowered to 140 N, so that the sitting comfort was lowered. In Comparative Example 6, since the bottom index was lowered to 0.42, and the hardness of the lower layer 14 was increased to 330 N, the sitting comfort was insufficient. In Comparative Example 7, since the bottom index was lowered to 0.38 and the hardness of the lower layer 14 was lowered to 270 N, a good sitting comfort was not obtained. In Comparative Example 8, the bottoming index was lowered to 0.47, the amount of deflection when a load of 100 N was applied was lowered to 3 mm, and the hardness of the upper layer 13 was set to 200 N, so that the desired sitting I didn't feel comfortable.
(Examples 13 and 14 and Comparative Examples 9 to 14)
In order to clarify a preferable range for the ratio of the total thickness D of the seat cushion 10 and the thickness D1 of the upper layer, in Examples 13 and 14, the total thickness D is 60 to 135 mm and the thickness D1 of the upper layer 13 is used. The ratio was 10 to 45%. Of course, the bottom index was set to 0.52 to 0.53, and the amount of deflection when a load of 100 N was applied was set in the range of the present invention of 4 to 5 mm.

  On the other hand, in Comparative Example 9, the total thickness D was thinned to 55 mm, and the bottom index was set low to 0.41. In Comparative Example 10, the total thickness D was increased to 140 mm, and the bottoming index was set low to 0.45. In Comparative Example 11, the ratio of the thickness of the upper layer 13 was increased to 46%, and the bottoming index was set low to 0.46. In Comparative Example 12, the ratio of the thickness of the upper layer 13 was reduced to 4%, the bottoming index was set low to 0.45, and the amount of bending when a load of 100 N was applied was set low to 3 mm. . In Comparative Example 13, the ratio of the thickness D1 of the upper layer 13 was increased to 46%, and the bottoming index was set low to 0.46. In Comparative Example 14, the thickness ratio of the upper layer 13 was reduced to 4%, the bottoming index was lowered to 0.47, and the amount of bending when a load of 100 N was applied was set to 3 mm.

  And actually sitting to each seat cushion 10 of Examples 13 and 14 and Comparative Examples 9-14, the seating comfort regarding the feeling of bottoming and the surface softness was evaluated based on the following criteria. The results are shown in Table 4.

  ○: There was no feeling of hitting the bottom, the surface was soft, and the sitting comfort was good. Δ: Sitting comfort was slightly poor. X: Sitting comfort was poor.

表４に示した結果より、実施例１３及び１４においては、底つき指数を０．５２〜０．５３、１００Ｎの荷重を作用させたときの撓み量を４〜５ｍｍという前提の下に、シートクッション１０全体の厚さＤが６０〜１３５ｍｍ及び上層１３の厚さＤ１の割合が１０〜４５％の範囲であることから良好な座り心地が得られた。従って、シートクッション１０全体の厚さＤは６０〜１３５ｍｍ及び上層１３の厚さＤ１の割合は１０〜４５％が好ましい範囲であった。

From the results shown in Table 4, in Examples 13 and 14, the seating index is 0.52 to 0.53, and the amount of deflection when a load of 100 N is applied is 4 to 5 mm. Since the ratio of the thickness D of the entire cushion 10 is 60 to 135 mm and the thickness D1 of the upper layer 13 is 10 to 45%, a good sitting comfort was obtained. Accordingly, the thickness D of the entire seat cushion 10 is preferably 60 to 135 mm, and the ratio of the thickness D1 of the upper layer 13 is preferably 10 to 45%.

  On the other hand, in Comparative Example 9, the bottoming index was lowered to 0.41, and the overall thickness D of the seat cushion 10 was reduced to 55 mm, so the sitting comfort was poor. In Comparative Example 10, since the bottoming index was lowered to 0.45 and the overall thickness D was increased to 140 mm, good sitting comfort could not be obtained. In Comparative Example 11, the bottoming index was lowered to 0.46 and the ratio of the thickness D1 of the upper layer 13 was increased to 46%, so that the sitting comfort was insufficient. In Comparative Example 12, the bottom index was lowered to 0.45, the amount of deflection when a load of 100 N was applied was lowered to 3 mm, and the ratio of the thickness D1 of the upper layer 13 was reduced to 4%. The comfort was insufficient. In Comparative Example 13, the bottoming index was lowered to 0.46 and the ratio of the thickness D1 of the upper layer 13 was increased to 46%, so the sitting comfort was lowered. In Comparative Example 14, the bottom index was lowered to 0.47, the amount of deflection when a load of 100 N was applied was lowered to 3 mm, and the ratio of the thickness D1 of the upper layer 13 was reduced to 4%. The comfort was insufficient.

In addition, the said embodiment can also be changed and implemented as follows.
・ In order to adjust the hardness of the polyurethane foam of the upper layer 13 and the hardness of the polyurethane foam of the lower layer 14, the blending amount of water as a foaming agent or the type and blending amount of the crosslinking agent may be varied. You can also

-It is also possible to form the seat cushion 10 with one layer of soft polyurethane foam, or with three or more layers.
-As an index constituting the seat cushion 10, the amount of bending at the time of 500N action or the amount of bending at the time of action of 1000N is used. You can also

  When molding the seat cushion 10 by the molding method, after molding the lower layer 14, the foam raw material for forming the upper layer 13 is injected into the fitting recess 15, and the upper layer 13 is molded under the same conditions as the lower layer 14. The upper layer 13 can be laminated on the lower layer 14 by molding.

Further, the technical idea that can be grasped from the embodiment will be described below.
(1) The polyurethane foam is obtained by reacting and foaming a raw material of a flexible polyurethane foam containing polyols, polyisocyanates, a catalyst and water as a foaming agent, and the two types of polyurethane foams are: The seat cushion according to claim 1 , wherein the seat cushion is configured so that the hardness varies depending on an isocyanate index in which an equivalent ratio of an isocyanate group of a polyisocyanate to an active hydrogen group including a polyol and water is expressed as a percentage. . When comprised in this way, in addition to the effect of the invention which concerns on Claim 1 , two types of polyurethane foams from which hardness differs can be obtained easily.

  (2) The polyurethane foam forming the upper layer is formed with an isocyanate index set to 100 or less, and the polyurethane foam forming the lower layer is formed with an isocyanate index set to exceed 100. The seat cushion according to the technical idea (1). When configured in this way, in addition to the effect of the invention according to the technical idea (1), the hardness of the two types of polyurethane foams can be easily adjusted.

  (3) The polyurethane foam forming the upper layer is formed with an isocyanate index set to 90 to 100, and the polyurethane foam forming the lower layer is formed with an isocyanate index exceeding 100 and set to 110 or less. The seat cushion according to the technical idea (2), characterized in that: When configured in this manner, the effect of the invention according to the technical idea (2) can be easily exhibited.

(4) Polyurethane foam materials containing polyols, polyisocyanates, catalyst and foaming agent were injected into the mold and reacted and foamed to produce upper and lower polyurethane foams, respectively. The method for producing a seat cushion according to claim 1 , wherein both polyurethane foams are joined and laminated. According to this manufacturing method, the seat cushion having the effect of the invention according to claim 1 can be easily manufactured by adjusting the hardness and setting the shape.

(A) is a perspective view which shows the seat cushion in embodiment, (b) is sectional drawing in the 1b-1b line | wire of (a). Sectional drawing which decomposes | disassembles and shows a seat cushion, in order to demonstrate the manufacturing method of a seat cushion.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Seat cushion, 13 ... Upper layer, 14 ... Lower layer, D ... Thickness of the whole seat cushion, D1 ... Upper layer thickness.

Claims (1)

Two types of soft polyurethane foams having different hardnesses are laminated by bonding with upper and lower two layers formed by a molding method, the upper layer has a hardness of 150 to 190 N, and the lower layer has a hardness of 280 to 190 320N, the total thickness is 60 to 135 mm, and the thickness of the upper layer is set to be 10 to 45% of the total thickness and thinner than the thickness of the lower layer 14, and is expressed by the following formula: A seat cushion characterized by having a bottom index of 0.48 to 0.55 and a deflection amount of 4 to 6 mm when a load of 100 N is applied.
Bottom index = [Bending amount when a load of 1000 N is applied (mm) −Bending amount when a load of 500 N is applied (mm)] / Bending amount when a load of 500 N is applied (mm)

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