Mattress

Abstract

To provide a mattress suitable for bedding by improving air permeability while utilizing the softness and repulsion of urethane foam and the fact that it can be manufactured at a low cost.SOLUTION: The first cushion portion includes a plurality of first slit portions that are parallel to the sides of the polygon with reference to the figure center position of the polygon and extend through the front and back of the first cushion portion such that the length of the first slit portions increases as the distance from the figure center position increases for each predetermined distance from the figure center position, and first support portions that support the plurality of first slit portions and extend radially from the figure center position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mattress, and more particularly to a mattress made of urethane foam that is comfortable to sleep on and easy to raise. [Background technology]

[0002] Because urethane foam has flexibility and moderate hardness, it is widely used as a component of mattresses and sheets. Therefore, it is common practice to change the hardness of urethane foam by forming specified slits in the foam (see Patent Document 1, etc.).

[0003] When urethane foam is used in bedding such as mattresses, the weight of the person is applied to the urethane foam in different ways depending on the part of the body. Therefore, in order to improve the comfort of sleeping, forming slits in the urethane foam, as in Patent Document 1, has been studied (see Patent Document 2, etc.).

[0004] The use of urethane foam in mattresses and other bedding has the advantages of being soft, resilient, and inexpensive to manufacture. However, urethane foam has poor breathability and tends to trap heat emitted from the human body. This can cause discomfort due to the user's own body heat, hindering a good night's sleep, and further improvements are being called for in nursing and care settings. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-031981 [Patent Document 2] Design Registration No. 1557883 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above points, and provides a mattress suitable as bedding by improving breathability while taking advantage of the softness and good resilience of urethane foam and the fact that it can be manufactured at a low cost.

Means for Solving the Problems

[0007] That is, the mattress of the embodiment is a mattress formed by laminating a first cushion part and a second cushion part having a higher hardness than the first cushion part below the first cushion part. The first cushion part is parallel to the sides of the polygon with respect to the center position of the polygon, and a plurality of first slit parts penetrating the front and back of the first cushion part whose length increases as it moves away from the center position of the figure at a predetermined distance from the center position of the figure, and a plurality of first slit parts support each other and include a first support part extending radially from the center position of the figure. The second cushion part is characterized by including a plurality of through holes penetrating the front and back of the second cushion part arranged on the circumference centered on the reference position.

[0008] Furthermore, the mattress may be formed by laminating a third cushion part having a higher hardness than the first cushion part below the second cushion part. The third cushion part has a plurality of third slit parts penetrating the front and back of the third cushion part, which are parallel to the sides at the positions of the sides of the polygon at a predetermined distance from the center position of the polygon with respect to the center position of the polygon, and whose length increases as it moves away from the center position of the figure, and a third support part that supports the plurality of third slit parts and extends radially from the center position of the figure.

[0009] Furthermore, for the mattress, in the measurement conforming to JIS K 6400-2(2012), the hardness of the first cushion part is H1, the hardness of the second cushion part is H2, and the hardness ratio Rh obtained by dividing the hardness H1 of the first cushion part by the hardness H2 of the second cushion part, the hardness ratio Rh may satisfy 0.5 < Rh < 0.95.

[0010] Furthermore, for the mattress, in the measurement conforming to JIS K 6400-2 (2012), the hardness of the third cushion part is H3, the hardness of the second cushion part is H2, and the hardness ratio Rg is defined as the hardness H3 of the third cushion part divided by the hardness H2 of the second cushion part. The hardness ratio Rg may satisfy 0.5 < Rg < 0.95.

[0011] Furthermore, in the mattress, the polygon in the first cushion part may be a hexagon, and the polygon in the third cushion part may be a hexagon.

[0012] Furthermore, in the mattress, the interval between the plurality of third slit parts in the third cushion part may be wider than the interval between the plurality of first slit parts in the first cushion part.

[0013] Furthermore, in the mattress, the first cushion part may have a first slit region where a plurality of first slit parts are densely formed and a first non-slit region where no first slit parts exist, and the third cushion part may have a third slit region where a plurality of third slit parts are densely formed and a third non-slit region where no third slit parts exist.

[0014] Furthermore, in the mattress, the second cushion part may be provided with a beam cushion part having a higher hardness than the second cushion part at the side part of the second cushion part.

Advantages of the Invention

[0015] The mattress of the present invention is a mattress comprising a first cushion portion and a second cushion portion that is harder than the first cushion portion and is layered underneath the first cushion portion; the first cushion portion has a plurality of first slit portions that penetrate the front and back of the first cushion portion, which are parallel to the sides of the polygon from the geometric center position of the polygon as a reference point and whose length increases as the distance from the geometric center position increases at predetermined distances from the geometric center position, and a first support portion that supports the plurality of first slit portions and extends radially from the geometric center position; and the second cushion portion has a plurality of through holes that penetrate the front and back of the second cushion portion, which are arranged on a circumference centered on a reference position, thereby taking advantage of the softness, good resilience, and low-cost manufacturing properties of urethane foam while improving breathability, making it suitable as bedding. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is an overall perspective view showing the cushion sections that make up the mattress of the embodiment separated from one another. [Figure 2] FIG. 2 is an overall plan view of a first cushion portion. [Figure 3] 1A is a partially enlarged plan view of a first cushion portion, and FIG. 1B is a partially enlarged plan view in which the shape of the first cushion portion is emphasized. [Figure 4] FIG. 4 is an overall plan view of a second cushion portion. [Figure 5] 1A is a partially enlarged plan view of the second cushion portion, FIG. 1B is a first partially enlarged plan view of the second cushion portion, and FIG. 1C is a second partially enlarged plan view of the second cushion portion. [Figure 6] FIG. 10 is an overall plan view of a third cushion portion. [Figure 7] 1A is a partially enlarged plan view of a third cushion portion, and FIG. 1B is a partially enlarged plan view in which the shape of the third cushion portion is emphasized. DETAILED DESCRIPTION OF THE INVENTION

[0017] The mattress disclosed in the embodiments is formed by stacking and integrating at least two cushion sections, preferably three cushion sections. The hardness of each cushion section is different from one another, creating a mattress with appropriate hardness and flexibility, and as bedding, it embodies a comfortable sleep while preventing the human body from sinking into it. The mattress of the embodiments can be used as general bedding, as well as bedding for nursing care and caregiving. In addition, the mattress of the embodiments can be used not only as bedding, but also as a cushion for the seat of a chair, a cushion to support posture, etc.

[0018] 1 is a perspective view showing each cushion section (first cushion section 10, second cushion section 20, and third cushion section 30) of a mattress 1 according to an embodiment, separated from one another. As shown in the figure, from above the mattress 1, the first cushion section 10 is stacked, and below the first cushion section 10, the second cushion section 20, which has a harderness than the first cushion section 10. Furthermore, the mattress 1 includes a third cushion section 30, which has a harderness than the first cushion section 10, stacked below the second cushion section 20.

[0019] The first cushion portion 10, the second cushion portion 20, and the third cushion portion 30 are all made of urethane foam (polyurethane foam). Therefore, when laminating the first cushion portion 10 and the second cushion portion 20, and when laminating the second cushion portion 20 and the third cushion portion 30, a known adhesive used for joining urethane foams is used. For example, a polyurethane-based adhesive is used. Depending on the properties and curing conditions of the adhesive, treatments required for processing the urethane foam, such as air drying, heating, and exposure to water vapor, are performed.

[0020] In the mattress 1 of the embodiment in FIG. 1, the hardest layer is the second cushion portion 20, and the first cushion portion 10 is less hard than the second cushion portion 20. The hardness of the third cushion portion 30 is between that of the first cushion portion 10 and the second cushion portion 20. The hardness of the third cushion portion 30 may be made harder than that of the second cushion portion 20. In this embodiment, beam cushion portions 40 (41, 42) are provided on longitudinal sides 28, 29 of the second cushion portion 20.

[0021] When using the mattress 1, the first cushion section 10 side is the side that comes into contact with the human body. Depending on the preference for shape, physique, etc., the mattress may be turned upside down so that the third cushion section 30 side comes into contact with the human body. The mattress 1 has a so-called reversible structure, and the top surface may be either the first cushion section 10 or the third cushion section 30. Furthermore, the third cushion section 30 can be omitted from the mattress, and the mattress may be a two-layer laminate (not shown).

[0022] Next, the structure of each of the first cushion portion 10, the second cushion portion 20, and the third cushion portion 30 will be described in detail with reference to FIGS.

[0023] 2 is a plan view showing the entire first cushion portion 10. A plurality of first slit portions 11 are formed in the first cushion portion 10. The first slit portions 11 are not groove-shaped, but penetrate the front and back of the first cushion portion 10. The first cushion portion 10 is formed with first slit regions 12 in which a plurality of first slit portions 11 are densely formed, and first non-slit regions 13 in which a plurality of first slit portions 11 are not present. In the figure, three first slit regions 12 are formed in the longitudinal direction of the first cushion portion 10, and first non-slit regions 13 are formed between the first slit regions 12.

[0024] 3A and 3B are enlarged plan views showing the first slit region 12 of the first cushion portion 10. FIG. 3B particularly emphasizes the polygonal shape. The first cushion portion 10 has a plurality of first slit portions 11 that penetrate the front and back of the first cushion portion 10. The first slit portions 11 are arranged parallel to side 1D of the polygon, a predetermined distance from the geometric center position 1C of the polygon, with the geometric center position 1C as the reference point. The length of the first slit portions 11 increases with increasing distance from the geometric center position 1C. There are a plurality of polygonal geometric center positions 1C on the surface of the first cushion portion 10.

[0025] As can be seen from the drawing, the polygonal shape of the first cushion portion 10 in this embodiment is a hexagon. Therefore, with a geometric center position 1C of the hexagon as a reference, multiple hexagons (six types in the drawing) are formed, with the sides gradually increasing in length from the geometric center position 1C and the size gradually increasing. The positions of the sides of each hexagon are first slit portions 11 (11a, 11b, 11c, 11d, 11e, 11f). The geometric center position 1C of the polygon and the side 1D of the polygon that is a predetermined distance away from the geometric center position 1C are defined for the convenience of explaining the arrangement of the first slit portions 11, and are not actually formed in the first cushion portion 10. In this embodiment, the polygon is a hexagon. Other shapes such as a triangle or a rectangle can also be used.

[0026] Additionally, to maintain the shape of the multiple first slit portions 11, first support portions 15 are provided between the first slit portions 11. The first support portions 15 support each of the multiple first slit portions 11 and extend radially from the geometric center position 1C. The first slit portions 11 are provided with gaps (spacing regions 14) of a predetermined width to maintain structural strength. This alone would simply reduce the hardness of the first cushion portion 10 uniformly. Therefore, by adding the radially extending first support portions 15 to the gaps (spacing regions 14) between the first slit portions 11, the first cushion portion 10 is provided with rigidity as a component in addition to its softness. Because the mattress 1 is primarily used as bedding, when a user lies on the first cushion portion 10 of the mattress 1, a large weight from the torso and other parts is applied to the first cushion portion 10. At this time, the softness to support the human body is provided by the multiple first slit portions 11, and at the same time, the rigidity to support the weight of the human body and prevent it from sinking more than necessary into the mattress 1 is provided by the first support portions 15.

[0027] In the first cushion portion 10, six first slit portions 11 are formed from the side of the geometric center position 1C. As will be described later in comparison with the third cushion portion 30, varying (increasing or decreasing) the number of first slit portions 11 creates variations in density in the urethane foam of the cushion portion, thereby enabling the hardness of the cushion portion itself to be changed. The structure of the first slit portions 11 and the first support portions 15 of the first cushion portion 10 is, for example, a structure that resembles a spider's web. The spacing regions 14 between the first slit portions 11 are the wefts in the spider's web, and the first support portions 15 are the warp threads in the spider's web. Thus, in the first cushion portion 10, both appropriate elongation when subjected to a load and rigidity to support the structure are balanced.

[0028] 4 is an overall plan view of the second cushion portion 20. The second cushion portion 20 is a core member that maintains the structural strength of the mattress 1. Therefore, the second cushion portion 20 has a different shape from the first cushion portion 10 described above and the third cushion portion 30 described below. In the second cushion portion 20, through holes 21 are formed over almost the entire surface. In this embodiment, each through hole 21 has a chamfered triangular shape (with the corners removed).

[0029] The second cushion portion 20 is arranged on a circumference 2D centered on a reference position 2C of the second cushion portion 20, and has a plurality of through holes 21 that penetrate the front and back of the second cushion portion 20. FIG. 5(A) is a partially enlarged plan view of the second cushion portion 20, showing the arrangement of the plurality of through holes 21. The plurality of through holes 21 are arranged evenly and radially along the circumference 2D centered on the illustrated reference position 2C. As can be seen from the illustration, the area of ​​the second cushion portion 20 other than the plurality of through holes 21 on the surface (i.e., the urethane foam member area 24) is formed larger and thicker than the first cushion portion 10. Therefore, the second cushion portion 20 is harder than the first cushion portion 10, and serves as a member that supports the structure and strength of the mattress 1.

[0030] The second cushion section 20 of this embodiment is further provided with beam cushion sections 40 (41, 42) on the longitudinal sides 28, 29 of the second cushion section 20. The beam cushion sections 40 are formed from urethane foam, just like the second cushion section 20. Furthermore, the beam cushion sections 40 have a harderness that is greater than that of the second cushion section 20. When using the mattress 1, if a user lying on the mattress tries to get up, they will place their hands on the longitudinal edges of the mattress 1 to try to pull themselves up. In this case, if the parts of the mattress 1 where the hands are placed have an appropriate hardness, sinking when the hands are thrust into the mattress is suppressed, making it easier to pull themselves up.

[0031] In particular, for users with weakened muscles due to caregiving or nursing, the presence of the second cushion section 20 prevents the mattress 1 from sinking when the user props up with their hands, reducing the strain on the user when getting up. If the beam cushion section 40 were provided over the entire second cushion section 20, the hardness of the second cushion section 20 itself would increase, making the mattress 1 less comfortable to sleep on. Therefore, the beam cushion section 40 is provided only in areas where it is needed when getting up.

[0032] 5(B) and (C) are enlarged plan views of the vicinity of the through-hole 21. In the second cushion portion 20 of the embodiment, the size of the through-hole 21 itself varies depending on the location of the second cushion portion 20. In FIG. 5(B), a triangular through-hole 21a with a side length of approximately 54 mm is formed. The position of the through-hole 21a corresponds to the center portion in the longitudinal direction of the second cushion portion 20, i.e., the position of the torso. Next, in FIG. 5(C), a triangular through-hole 21b with a side length of approximately 58 mm is formed. The position of the through-hole 21 corresponds to the end portion in the longitudinal direction of the second cushion portion 20, i.e., the position of the head and legs of the body.

[0033] Considering the intended use of the mattress 1, when a user sleeps, weight is concentrated on the torso area, causing the torso area to sink deeper than the head and leg areas. Therefore, by making the through-holes 21 in the center of the second cushion section 20 appropriately smaller than the other sections (21a<21b), the center section of the second cushion section 20 becomes relatively harder than the longitudinal end sections. This somewhat reduces the sinking caused by the weight of the torso area, making it easier for the user to turn over in bed and more comfortable to sleep in. It also makes it easier to get up. Note that the reference position 2C and circumference 2D of the second cushion section 20 are defined for the sake of convenience in explaining the arrangement of the through-holes 21 (21a, 21b), and are not actually formed in the second cushion section 20.

[0034] 6 is a plan view showing the entire third cushion section 30. The third cushion section 30 has the same structure as the above-mentioned first cushion section 10. The third cushion section 30 has a harder material than the first cushion section 10 by changing the spacing between the slit sections.

[0035] A plurality of third slit portions 31 are formed in the third cushion portion 30. The third slit portions 31 are not groove-shaped, but penetrate the front and back of the third cushion portion 30. The third cushion portion 30 is formed with third slit regions 32 in which a plurality of third slit portions 31 are densely formed, and third non-slit regions 33 in which a plurality of third slit portions 31 are not present. In the illustration, similar to the first cushion portion 10, three third slit regions 32 are formed in the longitudinal direction of the third cushion portion 30, and third non-slit regions 33 are formed between the third slit regions 32.

[0036] 7A and 7B are enlarged plan views showing the third slit region 32 of the third cushion portion 30. FIG. 7B particularly emphasizes the polygonal shape. The third cushion portion 30 has multiple third slit portions 31 that penetrate the front and back of the third cushion portion 30. The third slit portions 31 are arranged parallel to side 3D of the polygon, a predetermined distance from the geometric center 3C of the polygon. The third slit portions 31 become longer as they move away from the geometric center 3C. Multiple polygonal geometric center positions 3C exist on the surface of the third cushion portion 30.

[0037] As can be seen from the drawing, the polygonal shape of the third cushion section 30 of the embodiment is a hexagon, similar to that of the first cushion section 10. Therefore, with respect to a geometric center position 3C of the hexagon, multiple hexagons (five types in the drawing) are formed, with the sides gradually increasing in length and size from the geometric center position 3C as a reference. The positions of the sides of each hexagon are third slit sections 31 (31a, 31b, 31c, 31d, 31e). The number of third slit sections 31 formed in the third cushion section 30 is reduced compared to the first cushion section 10. The intervals between the third slit sections 31 (gap regions 34) are wider than the gap regions 14 between the first slit sections 11 described above. The polygonal geometric center position 3C and the side 3D of the polygonal shape, which is a predetermined distance away from the geometric center position 3C, are defined for the sake of convenience in explaining the arrangement of the third slit sections 31, and are not actually formed in the third cushion section 30.

[0038] Additionally, to maintain the shape of the multiple third slit portions 31, third support portions 35 are provided between the third slit portions 31. The third support portions 35 support each of the multiple third slit portions 31 and extend radially from the geometric center position 3C. The third slit portions 31 are spaced apart (spacing regions 34) with a predetermined width to maintain structural strength. The addition of the radially extending third support portions 35 in addition to the spacing between the third slit portions 31 (spacing regions 34) provides the third cushion portion 30 with flexibility and rigidity as a component. The third cushion portion 30 has fewer third slit portions 31 than the first cushion portion 10, and therefore contains a relatively greater amount of urethane foam than the first cushion portion 10. Therefore, the third cushion portion 30 is somewhat harder than the first cushion portion 10.

[0039] The shape formed by the multiple third slit portions 31 in the third cushion portion 30 is the same as that of the first cushion portion 10. Therefore, except for the hardness of the components, the third cushion portion 30 and the first cushion portion 10 have the same functions, actions, and effects. Depending on the preference of the user of the mattress 1, the third cushion portion 30 side may be the side that comes into contact with the human body, and the mattress 1 may be used in the opposite direction to that shown in FIG. 1.

[0040] As mentioned above, the first cushion section 10, second cushion section 20, and third cushion section 30 that make up the mattress 1 are each formed from urethane foam with different hardness. Therefore, to provide a mattress 1 that is suitable for the user, the relationship in hardness between the urethane foams of each section is relativized.

[0041] According to the embodiment, the following standards are used to define the physical properties of the urethane foam. The measurement results are also shown in Table 1. "Hardness and Compression Deflection": JIS K 6400-2 (2012) Part 2 6.4 A Method "Elongation": JIS K 6400-5(2012) Part 5 "Compressive residual strain": JIS K 6400-4 (2012), Part 4, 4.5.2, Method A "Resilient elasticity": JIS K 6400-3 (2012), Part 3

[0042]

Table 1

[0043] In each standard, "Hardness and compressive deflection": JIS K 6400-2 (2012), Part 2, 6.4, Method A can be measured as a predetermined value, which is convenient when defining the relative relationship between the first cushion part 10, the second cushion part 20, and the third cushion part 30.

[0044] Specifically, let the hardness of the first cushion part 10 be H1 and the hardness of the second cushion part 20 be H2. Then, let the hardness ratio obtained by dividing the hardness H1 of the first cushion part 10 by the hardness H2 of the second cushion part 20 be Rh (Rh = H1 / H2). At this time, the hardness ratio Rh converges within the range satisfying 0.5 < Rh < 0.95, preferably within the range satisfying 0.6 < Rh < 0.9.

[0045] According to the hardness relationship between the hardness H1 of the first cushion part 10 and the hardness H2 of the second cushion part 20, by setting the above hardness ratio Rh, an appropriate hardness is generated by the first cushion part 10 on the side where the user lies on the mattress 1. And the hardness of the mattress 1 itself is maintained by the second cushion part 20, improving convenience such as shape retention and ease of handling.

[0046] Next, let the hardness of the first cushion part 10 be H1, the hardness of the third cushion part 30 be H3, and let the hardness ratio obtained by dividing the hardness H2 of the second cushion part 20 by the hardness H3 of the third cushion part 30 be Rg (Rg = H2 / H3). At this time, the hardness ratio Rg converges within the range satisfying 0.5 < Rg < 0.95, preferably within the range satisfying 0.6 < Rh < 0.9.

[0047] According to the hardness relationship between the hardness H1 of the first cushion portion 10 and the hardness H3 of the third cushion portion 30, by using the aforementioned hardness ratio Rg, it becomes easy to select the surface of the mattress 1 according to the user's hardness preference.

[0048] The above measurements were taken for each cushion section individually. Therefore, the hardness was also measured when the three layers were stacked and processed into mattress 1. The results are shown in Table 2, which shows the results for the center and both ends of mattress 1 when first cushion section 10 was the uppermost surface and when third cushion section 30 was the uppermost surface.

[0049] [Table 2]

[0050] The first cushion section 10 is set to have a lower hardness than the third cushion section 30, so the numerical value is small. Also, when the mattress 1 is finished, the hardness of the second cushion section 20 is added, so the numerical value is higher than when they are used alone. For the top surface of the mattress 1, it is possible to choose between the first cushion section 10 and the third cushion section 30, allowing the user to use them freely according to their preference.

[0051] The first cushion section 10, second cushion section 20, and third cushion section 30 are punched using a punching machine, primarily using a Thomson blade. This allows multiple holes to be punched at once, which is advantageous for productivity. Furthermore, the formation of the first slit section 11, the third slit section 31, and the through-holes 21 ensures good breathability in the thickness direction throughout each urethane foam and the entire mattress 1. In particular, the hardness of the urethane foam can be changed by slightly varying the shapes of the first slit section 11 and the third slit section 31 in the first cushion section 10 and the third cushion section 30. [Explanation of symbols]

[0052] 1 mattress 10 First cushion section 11(11a, 11b, 11c, 11d, 11e, 11f) First slit section 12 First slit area 13 First non-slit region 14 Spacing area 15 1st support part 1C Figure center position 1D Edge 20 Second cushion section 21 through hole 24 Materials Area 2C Reference position 2D circumference 28,29 Sides 30 Third cushion section 31 (31a, 31b, 31c, 31d, 31e) Third slit section 32 Third slit area 34 Interval area 35 1st support part 3C Figure center position 3D Edges 40, 41, 42 Beam cushion section

Claims

1. A mattress comprising a first cushion portion and a second cushion portion, the second cushion portion being harder than the first cushion portion, stacked below the first cushion portion, The first cushion portion is a plurality of first slits that penetrate the front and back of the first cushion portion, the first slits being parallel to sides of the polygon from the geometric center position based on the geometric center position, and that increase in length as the distance from the geometric center position increases; a first support portion that supports the plurality of first slit portions together and extends radially from the geometric center position, The second cushion portion is A plurality of through holes are provided on a circumference of a circle centered at a reference position, and penetrate the front and rear of the second cushion portion. A mattress characterized by:

2. The mattress is formed by stacking a third cushion portion, which is harder than the first cushion portion, under the second cushion portion, The third cushion portion is a plurality of third slits that penetrate the front and rear of the third cushion portion, the third slits being parallel to the sides of the polygon at positions on the sides of the polygon that are a predetermined distance away from the center of the polygon, the lengths of the third slits increasing with increasing distance from the center of the polygon; The mattress according to claim 1 , further comprising: third support portions that support the plurality of third slit portions together and extend radially from the geometric center position.

3. In the measurement in accordance with JIS K 6400-2 (2012), the hardness of the first cushion portion is H1, the hardness of the second cushion portion is H2, and the hardness ratio obtained by dividing the hardness H1 of the first cushion portion by the hardness H2 of the second cushion portion is Rh, The mattress according to claim 1, wherein the hardness ratio Rh satisfies 0.5<Rh<0.

95.

4. In the measurement in accordance with JIS K 6400-2 (2012), the hardness of the third cushion portion is H3, the hardness of the second cushion portion is H2, and the hardness ratio obtained by dividing the hardness H3 of the third cushion portion by the hardness H2 of the second cushion portion is Rg, The mattress of claim 2 , wherein the firmness ratio Rg satisfies 0.5<Rg<0.

95.

5. 2. The mattress of claim 1, wherein the polygon in the first cushion portion is a hexagon.

6. 3. The mattress of claim 2, wherein the polygon in the third cushion portion is a hexagon.

7. The mattress according to claim 2 , wherein the spacing between the third slit portions of the third cushion portion is wider than the spacing between the first slit portions of the first cushion portion.

8. The mattress of claim 1, wherein the first cushion portion has a first slit region in which a plurality of the first slit portions are densely formed, and a first non-slit region in which a plurality of the first slit portions are not present.

9. The mattress of claim 2, wherein the third cushion portion has a third slit region in which a plurality of the third slit portions are densely formed, and a third non-slit region in which a plurality of the third slit portions are not present.

10. The mattress according to claim 1 , wherein the second cushion portion includes a beam cushion portion at a side of the second cushion portion, the beam cushion portion having a harderness than the second cushion portion.

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