JP7502937B2 - Cushioning material and vehicle seat equipped with same - Google Patents

Description

The present invention relates to a cushioning material and a vehicle seat equipped with the same. More specifically, the present invention relates to a cushioning material that is integrated into the pad main body of a vehicle seat, and a vehicle seat equipped with the above-mentioned cushioning material.

Generally, vehicle seats for automobiles and the like are constructed by disposing a pad body and a cushioning material integrated with the pad body on a metal seat frame that forms the framework. For example, Patent Document 1 describes how attaching a soft cushioning material (slab pad) manufactured by slab molding onto the pad body can provide a soft feel and improve the riding comfort of the occupants.

Japanese Patent Application Laid-Open No. 11-221131

However, according to the inventor's research, slab pads such as those described in Patent Document 1 generally have a large amount of air permeability in order to achieve a soft feel. As a result, they are easily crushed and lose their shape when an occupant sits on them. This means that they tend not to absorb high-frequency vibrations (10 Hz or higher) that occur during idling or driving, such as engine vibrations and road vibrations. As a result, high-frequency vibrations are directly transmitted to the occupant, causing an unpleasant trembling sensation in the occupant's thighs, etc.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a cushioning material that can reduce vibrations in the high frequency range (10 Hz or higher) and improve the riding comfort of passengers, and a vehicle seat equipped with the above cushioning material.

The invention of claim 1 is a vehicle seat comprising a pad main body and a cushioning material that is separate from the pad main body and is used integrated with the pad main body, wherein the cushioning material is a molded product having a thickness of 3 mm or more and 30 mm or less and comprising an inner layer and a skin layer having an apparent density higher than that of the inner layer, and wherein the air permeability measured using a test piece measuring 150 mm in length, 150 mm in width, and 20 mm in thickness according to JIS-K6400-7:2012, Method B , is 2 ^cm3 / ^cm2 /s or more and 22 ^cm3 / ^cm2 /s or less , and the cushioning material has an apparent density of 0.05 g/ ^cm3 or more and 0.085 g/ ^cm3 or less and has a higher apparent density than the pad main body .

According to the invention of claim 1, since the air permeability of the cushion material is 2 2 cm ³ /cm ² /s or less, the cushion material is not easily crushed and does not easily lose its shape when the occupant sits down. As a result, the cushion material plays the role of a so-called damper, and the cushion material can suitably absorb vibrations in the high frequency range (10 Hz or more). As a result, the uncomfortable trembling sensation occurring in the thighs of the occupant can be reduced. In addition, since the air permeability of the cushion material is 2 cm ³ /cm ² /s or more, the cushion material is ensured with appropriate breathability, and the occupant is not easily uncomfortable due to stuffiness. Therefore, the ride comfort of the occupant can be improved. In addition, according to the invention of claim 1, since the apparent density is 0.05 g/cm ³ or more and 0.085 g/cm ³ or less, the voids (cells) inside the cushion material are not easily crushed, and the vibration absorption can be further improved. In addition, the weight of the cushion material can be reduced, and the fuel efficiency of the vehicle can be improved. Furthermore, according to the invention of claim 1, since the product is a molded product having an inner layer and a skin layer having an apparent density higher than that of the inner layer, it is possible to highly suppress crushing and deformation when sitting on the seat, thereby further improving vibration absorption.

The invention of claim 2 is the invention of claim 1, characterized in that the air permeability of the cushioning material is 5 ^cm3 / ^cm2 /s or more and 22 ^cm3 / ^cm2 /s or less. According to the invention of claim 2, the effect of the invention of claim 1 can be exerted at a higher level. For example, at least one of improved vibration absorption in the high frequency range and reduced discomfort due to stuffiness can be realized.

The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the cushioning material is characterized in that a test piece having a size of 400 mm long x 400 mm wide x 20 mm thick is compressed to 75% of its original thickness with a pressure plate having a diameter of 200 mm (compression speed: 50 mm/min), and then the load is immediately removed and the pressure plate is returned to its initial position, and the same operation is repeated twice. The test piece is then left for 1 minute and compressed to 75% of its original thickness with the pressure plate (compression speed: 50 mm/min). The hysteresis loss rate measured by this is 17% or more and 28% or less. According to the invention of claim 3, in addition to the effect of the invention of claim 1 or 2, the resilience of the cushioning material can be suppressed. This suppresses seat collapse (disturbance of posture) when sitting, and improves seating comfort. In addition, the holding ability and posture stability during driving can be improved. In addition, the compression residual strain when sitting can be suppressed to be small, and the restoring ability when leaving the seat can be improved.

The invention of claim 4 is characterized in that the thickness of the cushion material is 5 mm or more and 30 mm or less in any one of the inventions of claims 1 to 3. According to the invention of claim 4, in addition to the effect of any one of the inventions of claims 1 to 3, the passenger is less likely to bottom out when seated, and vibration absorption can be further improved. Also, wobbling when seated can be suppressed, improving seating comfort.

The invention of claim 5 is the invention of any one of claims 1 to 4, characterized in that the cushioning material is such that the position of a pressure plate having a diameter of 200 mm when a load of 4.9 N is applied to a test piece having dimensions of 400 mm length x 400 mm width x 20 mm thickness is set as a reference position, the test piece is compressed to 75% of its original thickness (compression speed: 50 mm/min), the pressure plate is returned to the reference position at a speed of 50 mm/min, and then the test piece is left for ¹ minute, and then compressed to 25% of its original thickness by the pressure plate (compression speed: 50 mm/min), and the force (25% ILD hardness) after holding for 20 seconds is 30 N/314 cm2 or more and 180 N/314 cm2 or ^less . According to the invention of claim 5 , in addition to the effect of any one of the inventions of claims 1 to 4 , the voids (cells) inside the cushioning material are less likely to collapse, and vibration absorption can be further improved. In addition, excessive rigidity can be prevented, further reducing the resilience.

The invention of claim 6 is characterized in that in any one of the inventions of claims 1 to 5 , the difference in apparent density between the cushion material and the pad main body is 0.01 g/cm3 ^or more . According to the invention of claim 6, vibrations in the high frequency range are reduced, and a vehicle seat with improved ride comfort can be realized.

The invention of claim 7 is characterized in that in any one of the inventions of claims 1 to 6, the cushioning material is bonded to the pad body. According to the invention of claim 7 , the pad body and the cushioning material can be firmly integrated for a long period of time. Also, the workability during manufacturing can be improved.

1 is a front view of a vehicle seat according to an embodiment of the present invention; 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 2 is a schematic diagram showing a vibration test. 1 is a vibration transmissibility characteristic curve (horizontal axis: vibration frequency, vertical axis: vibration transmissibility).

The following describes preferred embodiments of the present invention. Note that matters other than those specifically mentioned in this specification that are necessary for implementing the present invention can be understood as design matters for a person skilled in the art based on conventional technology. The present invention can be implemented based on the matters disclosed in this specification and drawings and the technical common sense in the relevant field. Note that the notation "A to B" indicating a range in this specification includes the meaning of "A or more and B or less," as well as "preferably greater than A" and "preferably smaller than B."

<Vehicle seats>
FIG. 1 is a front view of a vehicle seat 10 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1. The vehicle seat 10 is attached to a vehicle (not shown) and constitutes a seating portion for an occupant. The vehicle seat 10 supports the body of an occupant. In this embodiment, the vehicle seat 10 is a seat back (backrest) against which the upper body back of the occupant abuts and supports the upper body (e.g., from the shoulders to the waist) of the occupant from behind. However, the vehicle seat 10 may be a seat cushion or the like that supports the lower body (e.g., from the buttocks to the thighs) of the occupant from below in the vertical direction. The vehicle seat 10 is typically covered with a cover body made of cloth, resin, leather, or the like, but the cover body is not shown in FIGS. 1 and 2.

The vehicle seat 10 includes a seat back frame (not shown) that forms the framework of the seat back, a pad body 12, and a cushion material 14. In the lateral direction, the cushion material 14 is disposed in the central portion 12c of the pad body 12. More specifically, the pad body 12 has a pair of grooves 12b (see FIG. 2) that are substantially U-shaped in cross section and extend in the vertical direction, and the cushion material 14 is disposed between the pair of grooves 12b. The cushion material 14 is disposed in each of the upper and lower portions of the central portion 12c of the pad body 12. Note that here, there is one pad body 12, but there may be two or more. Also, here, there are two cushion materials 14, but there may be only one, or there may be three or more. Also, here, the cushion material 14 is disposed only in the central portion 12c of the pad body 12, but in addition to or instead of the central portion 12c, the cushion material 14 may be disposed in the side portion 12s. Furthermore, the shape and arrangement of the pad body 12 and the cushion material 14 can be changed as appropriate, for example, depending on the shape of the vehicle seat 10.

The pad body 12 is attached to a seat back frame (not shown). The pad body 12 may be the same as that conventionally used for this type of application, and its material, properties, shape, etc. are not particularly limited. The pad body 12 is preferably made of polyurethane foam. The pad body 12 can be manufactured by a conventionally known method, for example, mold molding. The pad body 12 can be manufactured, for example, by injecting a polyurethane raw material containing a polyol component, a crosslinking agent, a foaming agent, a foam stabilizer, a catalyst, a connecting agent, and a polyisocyanate component into a mold and foam molding it. The polyol component of the pad body 12 may contain, for example, polypropylene glycol (PPG) and polymer polyol (POP). The polyisocyanate component of the pad body 12 may contain tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI).

The cushion material 14 is disposed at a position (seating position) where an occupant sits on the vehicle seat 10. The cushion material 14 is disposed on the seating surface side of the pad main body 12. The cushion material 14 constitutes an upper layer (e.g., a surface layer) of the seating position. The cushion material 14 is interposed between the pad main body 12 and at least a part of the occupant's body. Here, the cushion material 14 is interposed between the pad main body 12 and the upper body back of the occupant. The cushion material 14 may be covered with a cover body made of, for example, cloth, resin, leather, or the like. Here, the cushion material 14 is sheet-shaped (plate-shaped). The cushion material 14 is integrated with the pad main body 12.

In this specification, "integration" is a concept including attachment, adhesion, mounting, molding, insertion, etc. That is, the cushion material 14 may be placed on the pad body 12, may be irremovably attached to the pad body 12, may be detachably attached to the pad body 12 with Velcro (registered trademark) or the like, may be molded integrally with the pad body 12 (for example, insert molding in which the cushion material 14 is inserted into a mold for molding the pad body 12 and then the pad body 12 is foam molded), or may be inserted inside the pad body 12.

Here, the cushioning material 14 is fixed by adhesion to the pad body 12. The adhesion allows the pad body 12 and the cushioning material 14 to be firmly integrated for a long period of time. In this specification, "adhesion" refers to a general state in which the material is bonded by chemical or physical forces, and for example, refers to the cushioning material 14 being integrated with the pad body 12 via adhesive, double-sided tape, etc.

The cushioning material 14 is typically a resin foam. The cushioning material 14 is preferably made of polyurethane foam. The cushioning material 14 may be soft or semi-rigid polyurethane foam. The cushioning material 14 has a single-layer structure here. As will be described in detail later, the cushioning material 14 can be manufactured, for example, by injecting the polyurethane raw material described above into a mold and foaming it. The cushioning material 14 may be made, for example, of a crosslinked PPG polyol component as the first component (the component with the highest mixing ratio by mass; the same applies below), or may be made of a crosslinked PPG as the main component (a component that accounts for 50% or more by volume of the entire cushioning material 14).

The cushion material 14 needs to have an air permeability (average air permeability) of 2 to 25 cm ³ /cm ² /s. The cushion material 14 preferably has an air permeability of 5 cm ³ /cm ² /s or more, for example, 6 cm ³ /cm ² /s or more. By setting the air permeability to a predetermined value or more, appropriate breathability is ensured in the cushion material 14, and discomfort due to stuffiness is unlikely to occur when sitting. For example, even when the occupant is large and heavy, or when sitting for a long time during hot summer months, the ride comfort can be improved and the passenger can spend a comfortable time.

The cushion material 14 preferably has an air permeability of 22 cm ³ /cm ² /s or less, for example, 15 cm ³ /cm ² /s or less, 10 cm ³ /cm ² /s or less. By setting the air permeability to a predetermined value or less, the cushion material 14 acts as a so-called damper and absorbs vibrations during idling or running of the vehicle, particularly vibrations in the high frequency range (so-called trembling vibrations), thereby improving vibration absorption. As a result, the unpleasant trembling sensation generated in the thighs of the occupant can be relatively reduced compared to, for example, when only the pad body 12 is used without the cushion material 14 or when a slab pad such as that described in Patent Document 1 is used. The method for measuring the air permeability will be described in the test example described later.

The cushioning material 14 has a hysteresis loss rate of about 15% or more, preferably 17% or more, more preferably 20% or more, for example 22% or more, and about 30% or less, preferably 28% or less, more preferably 26% or less, for example 25% or less. By setting the hysteresis loss rate to a predetermined value or more, the resilience of the cushioning material can be suppressed. This can suppress the collapse of the seat (disturbance of posture) when the occupant sits down, and improve the seating comfort. In addition, the holding ability and posture stability during driving can be improved. By setting the hysteresis loss rate to a predetermined value or less, the compression residual strain when sitting down can be suppressed to be small, and the restoring ability when the occupant leaves the seat can be improved. This allows the above-mentioned effects to be stably exerted for a long period of time. The method for measuring the hysteresis loss rate will be explained in the test example described later.

The apparent density of the cushion material 14 is generally 0.03 g/cm ³ or more, preferably 0.04 g/cm ³ or more, more preferably 0.05 g/cm ³ or more, for example 0.06 g/cm ³ or more, and generally 0.1 g/cm ³ or less, preferably 0.095 g/cm ³ or less, more preferably 0.085 g/cm ³ or less, for example 0.08 g/cm ³ or less. By setting the apparent density to a predetermined value or more, the internal voids (cells) of the cushion material 14 are less likely to collapse when an occupant sits on the seat. This improves vibration absorption. By setting the apparent density to a predetermined value or less, the cushion material 14 can be made lighter and the weight can be reduced, improving the fuel efficiency of the vehicle.

The cushion material 14 preferably has an apparent density greater than that of the pad body 12. For example, the apparent density may be greater by 0.01 g/ ^cm3 or more, preferably 0.02 g/ ^cm3 or more, for example, 0.025 g/ ^cm3 or more. The method for measuring the apparent density will be described in the test examples described later.

The cushion material 14 has a 25% ILD hardness of about 20 N/314 cm2 ^or more, preferably 30 N/314 ^cm2 or more, more preferably ^{45 N} /314 cm2 ^or more, for example 50 N/314 cm2 ^or more, and about 200 N/314 cm2 or less, preferably 180 N/314 cm2 or less, more preferably 120 N/314 cm2 ^or less, for example 100 N/314 cm2 ^or less, 80 N/314 cm2 or ^less . By setting the 25% ILD hardness to a predetermined value or more, the internal voids (cells) of the cushion material 14 are less likely to collapse when an occupant sits on the seat. This can improve vibration absorption. By setting the 25% ILD hardness to a predetermined value or less, it can be suppressed that the rigidity becomes too large (in other words, that it rebounds too much). The method of measuring the 25% ILD hardness will be described in the test example described later.

The cushioning material 14 has a thickness t (average thickness, see FIG. 2) of approximately 3 mm or more, preferably 5 mm or more, for example 10 mm or more, more preferably 15 mm or more, and approximately 50 mm or less, preferably 30 mm or less, more preferably 25 mm or less. By setting the thickness t to a predetermined value or more, the occupant is less likely to bottom out when seated, even when the occupant is large and heavy, for example. This improves vibration absorption. By setting the thickness t to a predetermined value or less, lateral wobbling when the occupant is seated can be suppressed, improving seating comfort.

The cushioning material 14 is preferably a molded product having an inner layer and a skin layer (surface layer) with a higher apparent density than the inner layer. The skin layer typically forms the surface of the inner layer and is interposed between the inner layer and the body of the occupant. By providing a high-density skin layer, it is possible to highly suppress crushing and deformation when the occupant sits down. It is also possible to improve vibration absorption.

<Cushioning material manufacturing method>
The cushioning material 14 can be manufactured, for example, by a manufacturing method including the following preparation step and molding step. In the preparation step, a resin premix containing a polyol component and a polyisocyanate component are first prepared as polyurethane raw materials. The resin premix contains the polyol component, a foaming agent, a foam stabilizer, and a catalyst as essential components, and may further contain other additives. Examples of additives include a crosslinking agent, a connecting agent, a flame retardant, a filler, a colorant, a stabilizer, and the like.

Although not particularly limited, the polyol component may be a first component of PPG, and is preferably substantially (95% by mass or more of the entire polyol component) composed of PPG. The polyol component is preferably substantially free of POP (for example, POP is 10% by mass or less, 5% by mass or less of the entire polyol component). The blowing agent, foam stabilizer, catalyst, and additives (crosslinking agent, connecting agent, etc.) may be the same as those conventionally used for this type of application, and are not particularly limited. The crosslinking agent may be a polyhydric alcohol or an amine. The catalyst may be an amine compound. The blowing agent may be water. The foam stabilizer may be silicone oil.

In addition, although not particularly limited, the polyisocyanate component may preferably have MDI as the first component, and preferably substantially (at least 95% by mass of the entire polyisocyanate component) consists of MDI. It is preferable that the polyisocyanate component does not substantially contain TDI (for example, TDI is 10% by mass or less, 5% by mass or less of the entire polyisocyanate component).

Although not particularly limited, the mixing ratio of the crosslinking agent is preferably about 0.5 to 5 parts by mass when the polyol component is 100 parts by mass. The mixing ratio of the foaming agent is preferably about 2 to 5 parts by mass when the polyol component is 100 parts by mass. The mixing ratio of the catalyst is preferably about 0.35 to 2.5 parts by mass when the polyol component is 100 parts by mass. The mixing ratio of the foam stabilizer is preferably about 0.2 to 2 parts by mass when the polyol component is 100 parts by mass. The mixing ratio of the interconnecting agent is preferably about 0.5 to 5 parts by mass when the polyol component is 100 parts by mass. The mixing ratio of the polyisocyanate component is preferably about 25 to 80 parts by mass when the resin premix is 100 parts by mass.

In the molding process, the polyurethane raw material is foamed. Specifically, the polyurethane raw material prepared above, i.e., the resin premix and polyisocyanate, is mixed and injected into the mold body (lower mold), and the lid (upper mold) is closed. This causes a chemical reaction between the polyol component and the polyisocyanate component, and the resulting polymer is foamed using the gas (carbon dioxide) generated simultaneously with the reaction. The foaming conditions (molding temperature, etc.) may be the same as in the past. The molding temperature may be, for example, 40 to 90°C. In this manner, a cushioning material 14 made of polyurethane foam can be obtained.

The properties of the cushioning material 14 (e.g., the above-mentioned air permeability, hysteresis loss rate, apparent density, and 25% ILD hardness) depend largely on, for example, the molding method, the composition of the polyurethane raw material (e.g., the type of polyol component and/or polyisocyanate component), and the blending ratio of each component. For example, according to the study by the present inventor, in the slab molding as described in Patent Document 1, the air permeability of the molded product becomes larger than 25 ^cm3 / ^cm2 /s, and it is difficult to achieve the above-mentioned range of air permeability. For this reason, it is preferable to adopt a method other than slab molding, for example, mold molding, as the molding method. For example, the above-mentioned components are first mixed in the above-mentioned blending ratio to prepare a polyurethane raw material, and then the molded product is obtained by molding, whereby the cushioning material 14 having the above-mentioned air permeability can be suitably realized.

As described above, the cushioning material 14 can effectively absorb vibrations in the high frequency range (10 Hz or more) and reduce the unpleasant trembling sensation. In addition, the passengers are less likely to feel uncomfortable due to stuffiness. This improves the ride comfort of the vehicle. The cushioning material 14 can be suitably used in various types of vehicles, such as automobiles, such as passenger cars and trucks.

The following describes examples of the present invention, but is not intended to limit the present invention to those examples.

In Example 1, a cushioning material was produced by molding polyurethane raw materials. Specifically, a polyol component (PPG), 0.5 parts by mass of a crosslinking agent (Actocol (registered trademark) KL-210 (manufactured by Mitsui Chemicals SKC Polyurethanes Co., Ltd.)), 3.3 parts by mass of a blowing agent (water), a total of 1.35 parts by mass of a catalyst (TD-33A (manufactured by Huntsman), ZF-22 (manufactured by Huntsman), TOYOCAT (registered trademark)-D60 (manufactured by Tosoh Corporation)), 0.6 parts by mass of a foam stabilizer (SZ1346E (manufactured by Dow-Toray Industries, Inc.)), and 3.5 parts by mass of a connecting agent (Sannyx (registered trademark) FA-159 (manufactured by Sanyo Chemical Industries, Ltd.)) were mixed to prepare a resin premix. The catalysts were 0.35 parts by mass of TD-33A, 0.1 parts by mass of ZF-22, and 0.9 parts by mass of D60. Each part by mass is the blending ratio based on 100 parts by mass of the polyol component (PPG).

Next, the resin premix prepared above and MDI as a polyisocyanate component were mixed in a mass ratio of 100:36.35 and molded to prepare a cushioning material (Example 1) consisting of a molded product. For comparison, a cushioning material (Comparative Example 1) consisting of a slab molded product manufactured by slab molding was also prepared.

Next, a commercially available base pad material (pad body) was prepared. This base pad material contains PPG and POP as the polyol component, and uses a TDI/MDI blend as the polyisocyanate component. The following measurements were then carried out on the two types of cushioning materials (Example 1, Comparative Example 1) and the base pad material that were prepared. The results are shown in Table 1.

(1) Measurement of Air Permeability Using a Frazier-type air permeability tester, the air permeability was measured using a test piece measuring 150 mm long x 150 mm wide x 20 mm thick, applying Method B of JIS-K6400-7:2012.

(2) Measurement of hysteresis loss rate Measurement was performed with reference to the E method of JIS-K6400-2:2012. That is, first, using a Shimadzu Autograph AG-I type (manufactured by Shimadzu Corporation), a rectangular parallelepiped test piece with a length of 400 mm, width of 400 mm, and thickness of 20 mm was compressed to 75% of the initial thickness with a pressure plate with a diameter of 200 mm (compression speed: 50 mm/min). Then, the load was immediately removed, the pressure plate was returned to the initial position, and the test piece was left for 1 minute. This preliminary compression, in which compression and leaving were repeated, was performed a total of two times. Next, the test piece was left for 1 minute, and then compressed to 75% of the initial thickness with a pressure plate (compression speed: 50 mm/min) to draw a load-deflection curve. Then, the hysteresis loss rate was calculated from the load-deflection curve by the calculation method described in the E method of JIS-K6400-2:2012.

(3) Measurement of apparent density The external dimensions and weight of the test piece were measured to calculate the apparent density. In other words, the "apparent density" refers to the mass per unit volume, including the voids, of a material that has voids inside.

(4) Measurement of 25% ILD hardness The measurement was performed with reference to JIS-K6400-2:2012. That is, first, using a Shimadzu Autograph AG-I type (manufactured by Shimadzu Corporation), a rectangular parallelepiped test piece with a length of 400 mm, width of 400 mm, and thickness of 20 mm was compressed to 75% of its original thickness (compression speed: 50 mm/min) with a pressure plate with a diameter of 200 mm being set as the reference position when a load of 4.9 N was applied to the test piece. Next, the pressure plate was returned to the reference position at a speed of 50 mm/min. After this preliminary compression, the test piece was left for 1 minute, and then compressed to 25% of its original thickness with the pressure plate (compression speed: 50 mm/min), and the force (25% ILD hardness) after holding for 20 seconds was measured.

Next, the vibration transmissibility was measured. In other words, in order to reduce high-frequency vibrations (trembling vibrations) while the vehicle is idling or running, it is said that it is effective to lower the vibration transmissibility of the high-frequency vibrations (10 Hz or higher) in the vibration curve (horizontal axis: vibration frequency, vertical axis: vibration transmissibility) obtained from the vibration test. Therefore, a vibration test was performed using a seat cushion vibration tester V-0545 (manufactured by Saginomiya Seisakusho Co., Ltd.) to measure the vibration transmissibility.

Figure 3 is a schematic diagram showing the state of the vibration test. Specifically, first, only the base pad material (400 mm long x 400 mm wide x 40 mm thick) was placed on the vibration table, and the center of the base pad material was held down with a disk-shaped weight (iron grinding plate, 20 kg). In this state, the vibration table was subjected to sweep vibration at a constant acceleration (0.2 G) to apply vibration G with a frequency of 1 to 25 Hz. Then, the vibration G' of the measuring probe when the vibration G was applied was measured to determine the vibration transmissibility (G'/G) of the base pad material. Also, as shown in Figure 3, for the cushion material (Example 1, Comparative Example 1), a test piece (400 mm long x 400 mm wide x 20 mm thick) was placed on the base pad material to determine the vibration transmissibility (G'/G).

Figure 4 is a vibration transmissibility characteristic curve with the vibration frequency on the horizontal axis and the vibration transmissibility on the vertical axis. The smaller the vibration transmissibility value, the better the vibration absorption. As shown in Figure 4, when the cushioning material of Example 1 was used, the vibration transmissibility was relatively low compared to when only the base pad material or the cushioning material of Comparative Example 1 was used, especially in the high frequency range of 10 Hz or more.

Furthermore, the cushioning materials of Examples 2 to 4 were produced by molding the polyurethane raw material in accordance with Example 1. The cushioning materials of Example 2 were produced in the same manner as Example 1 except that the density was increased, the cushioning materials of Example 3 were produced in the same manner as Example 1 except that the foaming agent content was reduced, and the cushioning materials of Example 4 were produced in the same manner as Example 1 except that the type of polyisocyanate component (MDI) was changed. The above-mentioned measurements of (1) to (4) were also carried out for Examples 2 to 4 in the same manner as Example 1. Although not shown, the vibration transmissibility of the cushioning materials of Examples 2 to 4 was relatively low in the high frequency range of 10 Hz or more, similar to the cushioning material of Example 1, compared to the case where only the base pad material was used or the cushioning material of Comparative Example 1 was used.

Next, the cushioning materials (thickness 20 mm) of Examples 1 to 4 and Comparative Example 1 were subjected to a sensory evaluation of the following items. The sensory evaluation was performed by attaching the cushioning materials of Examples 1 to 4 and Comparative Example 1 to a vehicle seat of an actual vehicle (more specifically, the seat back and the pad body of the seat cushion), having a subject sit in the vehicle, and driving the actual vehicle at a speed of 40 to 60 km/h for a predetermined period of time. The results are shown in Table 2 with the following symbols.
Vibrating sensation: While the vehicle was idling or driving, (◎) no vibrating sensation was felt in the upper and lower body of the subject; (〇) a vibrating sensation was occasionally felt in the upper and lower body, but it was not bothersome; (×) a noticeable vibrating sensation was felt in the upper and lower body and it was uncomfortable. Stuffiness: (◎) no uncomfortable stuffiness even when driving for a long time; (〇) a somewhat stuffy feeling was felt after driving for a long time, but it was not bothersome; (×) a clear stuffy feeling was felt even after driving for a short time and it was uncomfortable. Hold: (◎) There was little lateral swaying or wobbling even when taking sharp turns, and it felt as if the cushioning was in close contact with the body; (〇) some lateral swaying or wobbling was felt when taking sharp turns; (×) there was a lot of lateral swaying and wobbling while driving, and the body felt unstable.

As shown in the evaluation results in Table 2, the use of the cushioning materials of Examples 1 to 4 relatively suppressed vibration compared to the use of the cushioning material of Comparative Example 1, which was also supported by the sensory evaluation. In addition, with the cushioning materials of Examples 1 to 4, by ensuring an air permeability of 2 cm ³ /cm ² /s or more, the discomfort of stuffiness was reduced. In particular, by ensuring an air permeability of 5 cm ³ /cm ² /s or more, the breathability was further improved, and it was possible to spend a comfortable time even when sitting for a long time. In addition, with the cushioning materials of Examples 1 to 4, by setting the hysteresis loss rate to 17% or more, for example 20% or more, lateral shaking and wobbling were suppressed, and a good holding feeling was achieved.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples given above.

10 Vehicle seat 12 Pad body 14 Cushioning material

Claims (7)

The pad body,
A cushioning material which is separate from the pad body and is used integrally with the pad body ;
A vehicle seat comprising :
The cushioning material is
The thickness is 3 mm or more and 30 mm or less,
A molded product comprising an inner layer and a skin layer having an apparent density higher than that of the inner layer ,
The air permeability measured using a test piece measuring 150 mm long x 150 mm wide x 20 mm thick according to JIS -K6400-7:2012, Method B, is 2 cm ³ /cm ² /s or more and 22 cm ³ /cm ² /s or less ,
The cushioning material has an apparent density of 0.05 g/ ^cm3 or more and 0.085 g/ ^cm3 or less , and has an apparent density higher than that of the pad body.
A vehicle seat comprising: The air permeability of the cushioning material is 5 cm ³ /cm ² /s or more and 22 cm ³ /cm ² /s or less.
2. The vehicle seat according to claim 1, wherein the seat is a seat for a vehicle . The cushioning material has a hysteresis loss rate of 17% or more and 28% or less, as measured by compressing a test piece having dimensions of 400 mm length × 400 mm width × 20 mm thickness with a pressure plate having a diameter of 200 mm to 75% of its initial thickness (compression speed: 50 mm/min), immediately removing the load and returning the pressure plate to its initial position, leaving it for 1 minute, and then repeating the same operation twice. The test piece is then left for 1 minute, and then compressed with the pressure plate to 75% of its initial thickness (compression speed: 50 mm/min).
3. A vehicle seat according to claim 1 or 2. The thickness of the cushioning material is 5 mm or more and 30 mm or less.
The vehicle seat according to any one of claims 1 to 3. The cushioning material is configured such that a load of 4.9 N is applied to a test piece having dimensions of 400 mm length x 400 mm width x 20 mm thickness using a pressure plate having a diameter of 200 mm, the position of the pressure plate being set as a reference position, the test piece is compressed to 75% of its original thickness (compression speed: 50 mm/min), and the pressure plate is returned to the reference position at a speed of 50 mm/min to perform pre-compression, the test piece is left for 1 minute, and then compressed to 25% of its original thickness using the pressure plate (compression speed: 50 mm/min), and the force (25% ILD hardness) after holding for 20 seconds is 30 N/314 cm2 or ^more and 180 N/314 cm2 or ^less .
The vehicle seat according to any one of claims 1 to 4. The difference in apparent density between the cushioning material and the pad body is 0.01 g/cm3 ^or more.
The vehicle seat according to any one of claims 1 to 5 . The cushioning material is bonded to the pad body.
The vehicle seat according to any one of claims 1 to 6.

Images