Molded urethane foam

Abstract

To provide a molded urethane foam having high air permeability and excellent uniformity of cells.SOLUTION: A molded urethane foam (1) wherein a skin portion (3) having a thickness of 15 mm from the surface has a first air permeability of not less than 50cm3 / (cm2·s) but not more than 150cm3 / (cm2·s) as determined by the Frasier method, a core portion (4) having a thickness of 15 mm from the skin portion (3) has a second air permeability of not less than 100cm3 / (cm2·s) but not more than 200cm3 / (cm2·s) as determined by the Frasier method, and the ratio of the first air permeability to the second air permeability is not less than 0.45 but not more than 0.90.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a molded urethane foam. [Background technology]

[0002] Molded urethane foam is used in vehicle interior materials such as seat cushions, headrests, and armrests. Molded urethane foam is also called a molded polyurethane foam. For example, molded urethane foam is produced by injecting a soft foaming material, which is a mixture of liquid A (a mixture of polyol, blowing agent, catalyst, foam stabilizer, crosslinking agent, etc.) and liquid B (an isocyanate) by stirring or impingement, into a mold, and then foaming and curing the mixture.

[0003] Patent Document 1 discloses a ventilated seat device in which a ventilation mechanism such as a blower fan is installed inside an automobile seat with through-holes. The ventilated seat device described in Patent Document 1 requires through-holes and air passages inside the seat to ensure breathability.

[0004] Patent Document 2 relates to a vehicle interior material made of a molded polyurethane resin foam. The polyurethane resin foam described in Patent Document 2 is produced using two incompatible polyols. The polyether polyols used are one containing 70% or more by weight of ethylene oxide and one containing 85% or more by weight of propylene oxide, which is thought to cause stickiness.

[0005] Patent Document 3 discloses a vehicle seat pad in which film-removed polyurethane foam is embedded in the back surface of the cushion pad to improve heat dissipation. The urethane foam used as a highly breathable member in Patent Document 3 is expensive due to the film-removal treatment. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-190358 [Patent Document 2] Japanese Patent Publication No. 2022-020678 [Patent Document 3] International Publication No. 2018 / 097208 Summary of the Invention [Problem to be solved by the invention]

[0007] To provide a molded urethane foam having high breathability and excellent cell uniformity. [Means for solving the problem]

[0008] According to an embodiment (for example, molded urethane foam 1 shown in FIG. 2), the side surfaces (four side surfaces intersecting both the front and back surfaces) of a urethane foam (for example, reference numeral 100 in FIG. 1) foamed in a 70 mm thick mold are trimmed, and the first air permeability measured by the Frazier method of a skin portion (for example, FIG. 3) 15 mm thick from the surface is 50 cm 3 / (cm 2 ·s) over 150cm 3 / (cm 2 ·s) below, The second air permeability by the Frazier method of the core part (for example, FIG. 4) having a thickness of 15 mm from the skin part is 100 cm 3 / (cm 2 ·s) over 200cm 3 / (cm 2 ·s) below, A molded urethane foam is provided in which the ratio of the first air permeability to the second air permeability is 0.45 or more and 0.90 or less. In the molded urethane foam of the embodiment, the third air permeability by the Frazier method of a thickness of 40 to 80 mm from the front surface to the back surface (for example, FIG. 2) is 50 cm 3 / (cm 2 ·s) over 120cm 3 / (cm 2 ·s) or less is desirable. [Effects of the Invention]

[0009] According to the present invention, a molded urethane foam having high breathability and excellent cell uniformity can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing an example of a molded urethane foam according to an embodiment. [Figure 2] 2 is a perspective view showing the molded urethane foam of FIG. 1 after the side surface has been removed. [Figure 3] FIG. 3 is a perspective view showing the skin portion of the molded urethane foam shown in FIG. 2. [Figure 4] FIG. 3 is a perspective view showing the core of the molded urethane foam shown in FIG. 2. [Figure 5] FIG. [Figure 6] FIG. 6 is a plan view of the jig shown in FIG. 5 . DETAILED DESCRIPTION OF THE INVENTION

[0011] The molded urethane foam of the embodiment will be described with reference to Figs. 1 to 6. Fig. 1 is a perspective view showing an example of the molded urethane foam of the embodiment. Fig. 2 is a perspective view of the molded urethane foam of Fig. 1 with the side surface removed. Fig. 3 is a perspective view showing the skin portion of the molded urethane foam shown in Fig. 2. Fig. 4 is a perspective view showing the core portion of the molded urethane foam shown in Fig. 2.

[0012] Molded urethane foam is one method for producing polyurethane foam. The molded urethane foam 1 shown in Figure 2 has a roughly rectangular parallelepiped shape. The thickness direction of the molded urethane foam 1 is defined as the z-axis direction. The direction intersecting the thickness direction of the molded urethane foam 1 is defined as the x-axis direction. The direction intersecting both the thickness direction z and the x-axis direction of the molded urethane foam 1 is defined as the y-axis direction. The molded urethane foam 1 has a surface 2 parallel to the xy plane with the largest area. Surface 2 is the design surface. The molded urethane foam 1 includes a skin portion 3 and a core portion 4. The skin portion 3 is a layer defined by the surface 2 (design surface) and a first surface 5 parallel to the xy plane, located 15 mm thick from the surface 2. The core portion 4 is a layer defined by the first surface 5 and a second surface 6 parallel to the xy plane, located 15 mm thick from the first surface 5. The thicknesses of the skin portion 3 and the core portion 4 are each 15 mm. There are no particular restrictions on the overall thickness of molded urethane foam 1, but it is preferably in the range of 40 mm to 80 mm, with 70 mm being particularly preferred. Here, the overall thickness is the distance parallel to the z-axis direction between front surface 2 and back surface 7, which is parallel to the xy plane.

[0013] The first air permeability of the skin part 3 by the Frazier method is 50 cm 3 / (cm 2 ·s) over 150cm 3 / (cm 2 It is desirable that the second air permeability of the core portion 4 by the Frazier method is 100 cm 3 / (cm 2 ·s) over 200cm 3 / (cm 2 It is preferable that the first air permeability is 50 cm 3 / (cm 2 s) or the second air permeability is less than 100 cm 3 / (cm 2 If the first air permeability is less than 150 cm s, the breathability of the molded urethane foam 1 may be reduced. 3 / (cm 2 s) or the second air permeability is 200 cm 3 / (cm 2If the first air permeability is greater than 80 cm s, the cell size of the molded urethane foam 1 becomes too large, resulting in a deterioration in mechanical strength. 3 / (cm 2 ·s) over 150cm 3 / (cm 2 ·s) or less.

[0014] The first air permeability is measured by the Frazier method in accordance with JIS K 6400-7 (Method B) (2012) on a 15 mm thick skin portion 3 cut out from molded urethane foam 1 along first surface 5. On the other hand, the second air permeability is measured by the Frazier method in accordance with JIS K 6400-7 (Method B) (2012) on a 15 mm thick core portion 4 cut out from molded urethane foam 1 along first surface 5 and then along second surface 6.

[0015] The ratio of the first air permeability to the second air permeability (first air permeability / second air permeability) is preferably 0.45 or more and 0.90 or less. If the ratio of the first air permeability to the second air permeability is less than 0.45, the breathability of the skin portion 3 is insufficient. On the other hand, if the ratio of the first air permeability to the second air permeability exceeds 0.90, molding defects such as depressions occur in the surface 2 of the molded urethane foam 1, and a good molding state cannot be maintained.

[0016] The third air permeability of the molded urethane foam 1 from the surface 2 to the back surface 7, measured by the Frazier method, is 50 cm 3 / (cm 2 ·s) over 120cm 3 / (cm 2 s) or less. 3 / (cm 2 If the third air permeability is less than 120 cm s, the breathability of the molded urethane foam 1 may be reduced. 3 / (cm 2If the third air permeability exceeds 60 cm s, the cell size of the molded urethane foam 1 varies greatly, causing depressions on the surface 2 of the molded urethane foam 1 and making it difficult to maintain a good molding condition. 3 / (cm 2 ·s) over 120cm 3 / (cm 2 s) or less, and the more preferable range is 50 cm 3 / (cm 2 ·s) over 110cm 3 / (cm 2 ·s) or less.

[0017] A third method for measuring air permeability will be described with reference to FIGS. 5 and 6. FIG. 5 is a perspective view of a jig used for measuring air permeability. FIG. 6 is a plan view of the jig shown in FIG. 5. The jig is a box-shaped resin container 10. The container 10 is formed, for example, from an acrylic plate. The thickness direction of the container 10 is defined as the z-axis direction. A direction intersecting the thickness direction z of the container 10 is defined as the x-axis direction. A direction intersecting both the thickness direction z and the x-axis direction of the container 10 is defined as the y-axis direction. Circular through-holes 13 and 14 are provided near the centers of the upper surface 11 and the lower surface 12 of the container 10, which are parallel to the xy plane. Each of the through-holes 13 and 14 has a diameter of 70 mm. The container 10 has an internal dimension Lx along the x-axis direction, an internal dimension Ly along the y-axis direction, and an internal dimension T along the z-axis direction, each of which is 100 mm. The plate thickness of the container 10 is, for example, 5 mm. The top surface 11 of the container 10 is detachable and functions as a lid.

[0018] The molded urethane foam 1 to be measured is placed in a container 10. The back surface 7 of the molded urethane foam 1 contacts the underside 12 of the container 10. The molded urethane foam 1 is in a state before the skin portion 3 and core portion 4 are cut out. The overall thickness of the molded urethane foam 1 is preferably 40 mm to 80 mm. Furthermore, the outer dimensions of the molded urethane foam 1 in the x-axis direction and the y-axis direction are preferably equal to or within +0 to +2 mm of the inner dimensions Lx and Ly, respectively. Therefore, the outer dimensions of the molded urethane foam 1 in the x-axis direction and the y-axis direction are preferably 100 mm to 102 mm, respectively. If the outer dimensions of the molded urethane foam 1 in the x-axis direction and the y-axis direction are larger than 102 mm, cut the molded urethane foam 100 shown in FIG. 1, for example, so that the outer dimensions fall within the range of 100 mm to 102 mm. In the molded urethane foam 1, the position corresponding to the through hole 13 on the upper surface 11 of the container 10 and the position corresponding to the through hole 14 on the lower surface 12 of the container 10 are the target areas for measuring air permeability using the Frazier method in accordance with JIS K 6400-7 (Method B) (2012).

[0019] It is desirable that the skin portion 3 has 60 cells (cells / 25 mm) or less, or that the core portion 4 has 30 cells (cells / 25 mm) or less, or that both of these conditions are satisfied.

[0020] By setting the number of cells to 60 (pieces / 25 mm) or less, the cells of the skin part 3 become larger, and the first air permeability according to the Frazier method is 50 cm 3 / (cm 2 ·s) over 150cm 3 / (cm 2 ·s) or less and maintains high breathability. For the core part 4, by setting the number of cells to 30 (cells / 25 mm) or less, the cells of the core part 4 become large, and the second air permeability by the Frazier method is set to 100 cm 3 / (cm 2 ·s) over 200cm 3 / (cm 2 ·s) or less and maintains high breathability.

[0021] When skin portion 3 has 60 cells (cells / 25 mm) or less and core portion 4 has 30 cells (cells / 25 mm) or less, molded urethane foam 1 can maintain high breathability.

[0022] The number of cells in the skin part 3 and the core part 4 is determined by counting the number of cells in a 10 mm interval on a straight line and multiplying by 2.5 according to the method in accordance with JIS K6400-1 (2004) Appendix 1. The measurement points are three, and the average value is obtained.

[0023] The rebound resilience of the molded urethane foam 1 is preferably 50% or more. A rebound resilience of 50% or more enables the realization of good mechanical properties such as high rebound. The rebound resilience is measured using a method in accordance with JIS K 6400-3 (2011). This method is performed by changing the thickness specified in JIS K 6400-3 to 30 mmt instead of 50 mmt or more. A more preferred range for the rebound resilience is 50% or more and 65% or less.

[0024] Molded urethane foam 100 has a 25% hardness of 80N / 314cm 2 More than 200N / 314cm 2 The 25% hardness is preferably less than or equal to 25%. The 25% hardness is measured in accordance with JIS K 6400-2 Method B (2012). This method requires a sample size of 350 mm x 350 mm x total thickness for JIS K 6400-2 Method B (molded urethane foam 100 shown in Figure 1).

[0025] Molded Urethane Foam 100 has an apparent density of 30 (kg / m) in accordance with JIS K 7222 (2005). 3 ) or more 50 (kg / m 3 ) or less is desirable.

[0026] Molded urethane foam 100 has a core density of 30 (kg / m) in accordance with JIS K 7222 (2005). 3 ) or more 50 (kg / m 3 ) or less is desirable.

[0027] Molded urethane foam 100 has a 25% CLD (Compression-Load-Deflection) of 20 (N / 100cm 2 ) or more 50(N / 100cm 2 The sample to be measured is molded urethane foam 100, with the dimensions of 100 mm x 100 mm x 30 mm after removing the top, bottom and side surfaces.

[0028] The molded urethane foam 100 preferably has an average cell diameter of 500 μm or more on the surface 2 and core 4. The average rib width on the surface 2 is preferably 100 μm or more.

[0029] The molded urethane foam 100 is produced, for example, by the following method. Isocyanate is added to a mixture of polyol, foam stabilizer, blowing agent, catalyst, crosslinker, etc., and the mixture is mixed. The resulting raw material mixture is poured into a mold and heated. The heating temperature is preferably in the range of 55°C to 65°C. The raw material mixture is foamed and expanded in the mold, and the foam is hardened to obtain a molded product. The molded product is then subjected to a crushing process after being demolded. The crushing process is a process in which the molded product is compressed to destroy the cell membrane of the molded product.

[0030] Examples of polyols include polypropylene glycol (PPG) and polymer polyol (POP). One or more types of polyols may be used.

[0031] As the isocyanate, for example, Cosmonate TM-20 (trade name) or tolylene diisocyanate manufactured by Mitsui Chemicals, Inc. is preferably used. The amount of isocyanate to be added is preferably an amount such that the isocyanate index of the entire raw material is a value of 90 or more and 120 or less. The isocyanate index is an index of the reaction ratio between hydroxyl groups and isocyanate groups.

[0032] The blowing agent may, for example, consist of water.

[0033] The foam stabilizer may be, for example, a silicone-based foam stabilizer. Any foam stabilizer commonly used in the production of urethane foam may be used, including silicone-based foam stabilizers, fluorine-containing compound-based foam stabilizers, and known surfactants. Silicone-based foam stabilizers with a short molecular weight or low viscosity are preferred. Silicone-based foam stabilizers with a short molecular weight or low viscosity are more effective at promoting the external diffusion of bubbles generated from the raw material mixture in the mold than at promoting foaming. A desirable silicone-based foam stabilizer is Niax silicone L-838, a product name sold by Momentive Performance Materials Japan, LLC. This silicone-based foam stabilizer promotes the external diffusion of bubbles generated from the raw material mixture in the mold. Therefore, when used in combination with a foam stabilizer for conventional urethane foam, it is possible to stabilize the cell structure while maintaining high breathability. The cell count of urethane foam can be adjusted by selecting the type and weight of foam stabilizer in the raw materials. For example, using a highly active foam stabilizer helps the bubbles generated during urethane foaming to remain independent and stable, thereby increasing the cell count.

[0034] The amount of foam stabilizer in the raw material is preferably 0.05 to 0.5 parts by weight.

[0035] Examples of the catalyst include amine catalysts, tin catalysts, etc. The type of catalyst used may be one or more types.

[0036] The raw materials may further contain additives. Examples of additives include antioxidants, flame lamination modifiers, flame retardants, hygiene improvers, pigments, and natural products. Examples of flame retardants include melamine, urea, polyvinyl chloride (PVC), zinc oxide, antimony trioxide, expandable graphite, and phosphorus-based solid materials. Examples of hygiene improvers include antibacterial agents, anti-mite agents, anti-fungal agents, antiviral agents, and deodorizers. Examples of natural products include green tea powder, catechin, charcoal, needle leaf powder, and herbs. The additives used may be one or more types. [Example]

[0037] Examples of the present invention will be described in detail below.

[0038] Examples 1 to 7 A mixture of catalyst 1, blowing agent 1, polyols (connecting agent 2, POP, and PPG), foam stabilizer 2, foam stabilizer 3, foam stabilizer 5, catalyst 3, and crosslinking agent 2 listed in Tables 3 to 5 was mixed with isocyanate by stirring or high-pressure collision. The manufacturer name, raw material name or product name, Ohv (hydroxyl value), number of parts (parts by weight) of each component, and target density of the molded urethane foam are shown in Tables 3 to 5. The isocyanate index is also shown in Table 1. The resulting raw material mixture was poured into a mold heated to a constant temperature, e.g., 60°C, and heat-treated. The raw material mixture was foamed and expanded in the mold, and then the foam was cured by the heat of the mold to obtain molded flexible molded urethane foams of the examples. The molded urethane foams of Examples 1 to 6 had a thickness of 70 mm and lengths of two sides (sides parallel to the x-axis and y-axis directions, respectively) intersecting the thickness direction (z-axis direction) of 350 mm each. On the other hand, the molded urethane foam of Example 7 had a thickness of 40 mm and the lengths of the two sides intersecting the thickness direction were each 350 mm.

[0039] (Comparative Example 1) A mixture of crosslinking agent 1, catalyst 1, catalyst 2, blowing agent 1, foam stabilizer 1, polyols (connecting agent 1, POP, and PPG), crosslinking agent 3, and foam stabilizer 4 listed in Tables 3 to 5 was mixed with isocyanate by stirring or high-pressure collision. The manufacturer name, raw material name or product name, Ohv (hydroxyl value), number of parts (parts by weight) of each component, and target density of the molded urethane foam are shown in Tables 3 to 5. The isocyanate index is also shown in Table 1. The resulting raw material mixture was poured into a mold heated to a constant temperature, e.g., 60°C, and heat-treated. The raw material mixture was foamed and expanded in the mold, and then the foam was cured by the heat of the mold to obtain the molded urethane foam of Comparative Example 1. The flexible molded urethane foam of Comparative Example 1 had a thickness of 70 mm and lengths of two sides (sides parallel to the x-axis and y-axis directions) intersecting the thickness direction (z-axis direction) of 350 mm each.

[0040] (Comparative Example 2) Isocyanate was added to a mixture of Catalyst 1, Catalyst 3, Blowing Agent 1, Polyols (Connection Agent 2, POP, and PPG), Foam Stabilizer 2, Foam Stabilizer 3, and Crosslinker 2, as listed in Tables 3 to 5, and the mixture was mixed. The manufacturer name, raw material name or product name, Ohv (hydroxyl value), number of parts (parts by weight) of each component, and target density of the molded urethane foam are shown in Tables 3 to 5. The isocyanate index is also shown in Table 1. The resulting raw material mixture was poured into a mold heated to a constant temperature, e.g., 60°C, and heat-treated. The raw material mixture was foamed and expanded in the mold, and the foam was then cured by the heat of the mold to obtain a flexible molded urethane foam of Comparative Example 2. The molded urethane foam of Comparative Example 2 had a thickness of 70 mm and lengths of two sides (sides parallel to the x-axis and y-axis directions) intersecting the thickness direction (z-axis direction) of 350 mm each.

[0041] The mass, 25% hardness, apparent density, core density, hysteresis loss rate according to JIS K 6400-2, 25% CLD, rebound resilience, first to third air permeabilities, air permeability ratio (first air permeability B / second air permeability C), flammability (FMVSS302), number of cells in the skin layer (skin portion), number of cells in the core layer (core portion), and appearance and moldability of the molded urethane foams of Examples 1 to 7 and Comparative Examples 1 and 2 are shown in Tables 1 and 2. The 25% hardness, core density, hysteresis loss rate, and 25% CLD of the molded urethane foam of Example 7 were not measured. The 25% hardness, apparent density, core density, 25% CLD, rebound resilience, first to third air permeabilities, air permeability ratio (first air permeability B / second air permeability C), number of cells in the skin layer (skin portion), and number of cells in the core layer (core portion) were each measured according to the methods described above. Appearance and moldability are shown below. If the molded urethane foam had an uneven surface or had cavities inside, it was deemed unsuitable for use as a product and was marked x.

[0042] [Table 1]

[0043] [Table 2]

[0044] [Table 3]

[0045] [Table 4]

[0046] [Table 5]

[0047] As is clear from Tables 1 and 2, the molded urethane foams of Examples 1 to 7 had a first air permeability B of 50 cm3 measured by the Frazier method for the skin portion.3 / (cm 2 ·s) over 150cm 3 / (cm 2 ·s) or less, and the second air permeability C of the core part by the Frazier method is 100 cm 3 / (cm 2 ·s) over 200cm 3 / (cm 2 s), the ratio of the first air permeability B to the second air permeability C (B / C) is 0.45 or more and 0.90 or less, and the third air permeability A by the Frazier method of the part having the total thickness (40 mm or more and 80 mm or less) is 50 cm 3 / (cm 2 ·s) over 120cm 3 / (cm 2 On the other hand, the molded urethane foam of Comparative Example 1 has a B / C ratio of 0.45 or more and 0.90 or less, but the second air permeability is 100 cm 3 / (cm 2 In addition, the molded urethane foam of Comparative Example 2 had a first air permeability B of 50 cm 3 / (cm 2 ·s) over 150cm 3 / (cm 2 ·s) or less, and the second air permeability C of the core part by the Frazier method is 100 cm 3 / (cm 2 ·s) over 200cm 3 / (cm 2 s) or less, and the third air permeability by the Frazier method of the part having the entire thickness is 50 cm 3 / (cm 2 ·s) over 120cm 3 / (cm 2 Although the B / C ratio was below 0.90,

[0048] The urethane foams of Examples 1 to 7 had excellent mechanical properties such as impact resilience while maintaining high breathability. The urethane foams of Examples 1 to 7 were also flame retardant. In contrast, the urethane foam of Comparative Example 1 had poor breathability in the core. The urethane foam of Comparative Example 2 had a problem with appearance due to surface irregularities.

[0049] The ethylene oxide content of the polyol used as the raw material for the urethane foams of Examples 1 to 7 is less than 70%. In Examples 1 to 7, high breathability is achieved by using polyols with low ethylene oxide content.

[0050] The molded urethane foam of the embodiment described above has a first air permeability B of 50 cm2 by the Frazier method of the skin portion. 3 / (cm 2 ·s) over 150cm 3 / (cm 2 ·s) or less, and the second air permeability C of the core part by the Frazier method is 100 cm 3 / (cm 2 ·s) over 200cm 3 / (cm 2 ·s) or less, and the ratio (B / C) of the first air permeability B to the second air permeability C is 0.45 or more and 0.90 or less. In addition, the third air permeability A of the part having the entire thickness measured by the Frazier method is 50 cm 3 / (cm 2 ·s) over 120cm 3 / (cm 2 The molded urethane foam of this embodiment can ensure high breathability and impact resilience.

[0051] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention. [Explanation of symbols]

[0052] 1...molded urethane foam, 2...surface, 3...skin portion, 4...core portion, 5...first surface, 6...second surface, 7...back surface, 10...container, 11...top surface, 12...bottom surface, 13...through hole, 14...through hole, 100...molded urethane foam.

Claims

1. The first air permeability of the skin part 15 mm thick from the surface is 50 cm 3 / (cm 2 ・s) or more 150cm 3 / (cm 2 ・s) below, The second air permeability by the Frazier method of the core part having a thickness of 15 mm from the skin part is 100 cm 3 / (cm 2 ・s) or more 200cm 3 / (cm 2 ・s) below, A molded urethane foam, wherein the ratio of the first air permeability to the second air permeability is 0.45 or more and 0.90 or less.

2. The third air permeability measured by the Frazier method from the front to the back is 50 cm 3 / (cm 2 ・s) or more 120cm 3 / (cm 2 2. The molded urethane foam according to claim 1, wherein the viscosity is less than or equal to s.

3. 3. The molded urethane foam according to claim 1, wherein the impact resilience is 50% or more and 65% or less.

4. 3. The molded urethane foam according to claim 2, wherein the thickness from the front surface to the back surface is 40 mm or more and 80 mm or less.

5. 3. The molded urethane foam according to claim 1, wherein the skin portion has 60 or less cells per 25 mm, or the core portion has 30 or less cells per 25 mm.

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