mattress

Abstract

We offer mattresses that provide both ease of turning over in bed and a comfortable sleeping experience. [Solution] According to an embodiment of the present invention, a mattress 1 is provided comprising a first soft polyurethane foam layer 2 having a hysteresis loss rate of less than 25%. The thickness T1 of the first soft polyurethane foam layer 2 accounts for 50% or more of the total thickness T.

Description

[Technical Field]

[0001] This invention relates to mattresses, particularly mattresses using soft polyurethane foam. [Background technology]

[0002] Mattresses for bedding using flexible polyurethane foam are known. For example, Patent Document 1 discloses a mattress made by laminating flexible polyurethane foams with different physical properties, wherein a highly elastic polyurethane foam layer with rebound elasticity exceeding 50% is laminated with a flexible polyurethane foam as a surface layer with rebound elasticity of 25% or less and a hysteresis loss rate of 35% or less.

[0003] The mattress described in Patent Document 1 has an overall thickness of 80 mm to 200 mm, and the thickness of the surface layer is 30 mm to 85 mm, but the thickness of the surface layer changes along the direction from the head to the feet.

[0004] The mattress described in Patent Document 1 has problems in achieving both ease of turning over in bed and sleeping comfort. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-353 [Overview of the project] [Problems that the invention aims to solve]

[0006] We offer mattresses that provide both ease of turning over in bed and a comfortable sleeping experience. [Means for solving the problem]

[0007] According to an embodiment of the present invention, a mattress is provided comprising a first flexible polyurethane foam layer having a hysteresis loss rate of less than 25%, wherein the thickness of the first flexible polyurethane foam layer accounts for 50% or more of the total thickness. [Effects of the Invention]

[0008] We can provide mattresses that offer both ease of turning over and a comfortable sleeping experience. [Brief explanation of the drawing]

[0009] [Figure 1] A cross-sectional view showing an example of a mattress according to the embodiment. [Figure 2] A graph showing the relationship between elongation and tensile strength of the first to third flexible polyurethane foam layers. [Figure 3] A cross-sectional view showing another example of the mattress of the embodiment. [Figure 4] A schematic diagram showing the general characteristics of the device used to measure the total resistance to turning over in bed. [Figure 5] A cross-sectional view of the apparatus shown in Figure 4, cut along a direction intersecting the axial direction of the rotating body. [Figure 6] Figure 5 is a cross-sectional view showing the rotating body rotated 90 degrees. [Figure 7] A graph showing an example of the relationship between rolling resistance measured using the apparatus shown in Figure 4 and the rotation angle of the rotating body. [Modes for carrying out the invention]

[0010] The mattress according to the embodiment of the present invention is used, for example, as an overlay mattress. The overlay mattress is used, for example, by being placed on top of a futon or mattress.

[0011] The mattress of the embodiment of the present invention will be described with reference to Figures 1 to 3. Figure 1 is a cross-sectional view of an example of the mattress of the embodiment, cut along the thickness direction. Figure 2 is a graph showing the relationship between the elongation and tensile strength of the first to third soft polyurethane foam layers used in the mattress of the embodiment. Figure 3 is a cross-sectional view of another example of the mattress of the embodiment, cut along the thickness direction. In Figures 1 and 3, the thickness direction of the mattress is assumed to be parallel to the z-axis direction. The front and back surfaces of the mattress are assumed to be parallel to the xy-plane.

[0012] As shown in Figures 1 and 3, the mattress of the embodiment comprises multiple flexible polyurethane foam layers. The mattress 1 shown in Figure 1 is a laminate having a two-layer structure consisting of an upper flexible polyurethane foam layer 2 and a lower flexible polyurethane foam layer 3. The two layers are bonded together using, for example, an adhesive, a hot melt sheet, or a hot melt material. An example of an adhesive is a synthetic rubber-based latex adhesive such as Bond WG320R, a product name of Konishi Corporation. The mattress 1 may also be covered with a mattress cover (not shown) for protection.

[0013] The soft polyurethane foam layer 2 is composed of a first soft polyurethane foam layer having a hysteresis loss rate of less than 25%. The soft polyurethane foam layer 3 is not particularly limited as long as it has a hysteresis loss rate different from that of the first soft polyurethane foam layer 2. The soft polyurethane foam layer 3 can be formed, for example, from a second soft polyurethane foam layer having a hysteresis loss rate of 25% or more and less than 35%, or a third soft polyurethane foam layer having a hysteresis loss rate of 35% or more. The hysteresis loss rate is measured by a method according to JIS K 6400-2 (Method E): 2012. The thickness of the sample in the measurement of the hysteresis loss rate according to JIS K 6400-2 (Method E) is specified as 50 ± 2 mm. In the case of two or more layers, the total thickness when the samples are stacked should be 50 ± 2 mm. For example, it can be adjusted in any way, such as using two 25-mm-thick samples, three 16.7-mm-thick samples, four 12.5-mm-thick samples, five 10-mm-thick samples, etc.

[0014] When the thickness (total thickness) of the mattress 1 is T and the thickness of the first soft polyurethane foam layer 2 is T1, it is desirable that the ratio (T1 / T) of the thickness T1 of the first soft polyurethane foam layer 2 to the thickness T of the mattress 1 be 50% or more. Since the first soft polyurethane foam layer 2 has a hysteresis loss rate of less than 25%, it has excellent resilience. By setting the thickness ratio (T1 / T) to 50% or more, when the user turns over, it is easier to bend at points rather than on the surface, so the user can easily change positions or turn over. Therefore, a mattress that can improve the quality of sleep can be provided. It is desirable that the thickness ratio (T1 / T) be 75% or less. By setting the thickness ratio (T1 / T) to 50% or more and 75% or less, both comfort and ease of turning over can be achieved.

[0015] The thickness (total thickness) T of the mattress 1 is desirably in the range of 40 mm or more and 60 mm or less. A more preferable thickness T is about 50 mm.

[0016] The first soft polyurethane foam layer 2 has a 10% hardness of 30 N / 314 cm 2 or less, and a 40% hardness of 50 N / 314 cm 2 or less. This makes the initial hardness of the mattress 1 softer, reducing the rolling resistance at the beginning of turning over. As a result, it becomes easier to turn over. Here, the 10% hardness is the value measured with a compression rate of 10% as defined in JIS K 6400-2 (Method A): 2012. The 40% hardness is measured by the method defined in JIS K 6400-2 (Method A): 2012. The thickness of the sample in hardness measurement is specified as 50 ± 2 mm. In the case of two or more layers, the total thickness when the samples are stacked should be 50 ± 2 mm. For example, it can be adjusted in any way, such as two 25-mm-thick samples, three 16.7-mm-thick samples, four 12.5-mm-thick samples, five 10-mm-thick samples, etc.

[0017] The mattress 1 includes, as the soft polyurethane foam layer 3, a second soft polyurethane foam layer having a hysteresis loss rate of 25% or more and less than 35%, or a third soft polyurethane foam layer having a hysteresis loss rate of 35% or more.

[0018] The second soft polyurethane foam layer has a hysteresis loss rate of 25% or more and less than 35%, and is harder and more difficult to stretch than the first soft polyurethane foam layer 2. Therefore, the second soft polyurethane foam layer is difficult to sink due to the user's body position change or turning over and has a restoring force. On the other hand, the third soft polyurethane foam layer has a hysteresis loss rate of 35% or more. The third soft polyurethane foam layer has excellent body pressure dispersion. The third soft polyurethane foam layer has a low urethane reaction force and thus a small restoring force. Therefore, when the ratio of the thickness of the third soft polyurethane foam layer to the total thickness T of the mattress is high (for example, 70% or more), the user's body is likely to sink into the mattress 1, making it difficult to turn over. Also, bottoming occurs and the comfort deteriorates.

[0019] The ratio of the thickness B of the soft polyurethane foam layer 3 to the overall thickness T of mattress 1 should ideally be between 30% and 50%. This results in mattress 1 that allows for easy turning and provides good sleeping comfort. It is possible to create a mattress that allows for easy turning regardless of whether the first soft polyurethane foam layer is located on the front or back of the mattress. In a two-layer laminated structure, the softer layer compresses first, followed by the harder layer. Since the first soft polyurethane foam layer compresses in the same way whether it is on the front or back of the mattress, it is possible to create a mattress that allows for easy turning and provides good sleeping comfort without having to worry about which side is up.

[0020] Table 1 below shows examples of the tensile strength and elongation of the first to third flexible polyurethane foam layers. Tensile strength is measured according to the method based on JIS K 6400-5 (Type 2):2012, and the unit is (kPa). Elongation is measured according to the method based on JIS K 6400-5 (Type 2):2012, and the unit is (mm). The first to third flexible polyurethane foam layers can be classified by hysteresis loss rate as low hysteresis loss, medium hysteresis loss, and high hysteresis loss. For the first flexible polyurethane foam layer with low hysteresis loss, for example, polyurethane foam manufactured by Toyo Quality One Co., Ltd. (I: product number GTF48) can be used. For the second flexible polyurethane foam layer with medium hysteresis loss, for example, polyurethane foam manufactured by Toyo Quality One Co., Ltd. (II: product number 30HRABMR) can be used. For the third flexible polyurethane foam layer with high hysteresis loss, for example, polyurethane foam manufactured by Toyo Quality One Co., Ltd. (III: product number LR48ABMR) can be used.

[0021] [Table 1]

[0022] Figure 2 shows the relationship between elongation and tensile strength of the first to third flexible polyurethane foam layers. In Figure 2, the horizontal axis X represents elongation (mm), and the vertical axis Y represents tensile strength (kPa). The slope between elongation and tensile strength of the first flexible polyurethane foam layer with low hiss is given by relation (a) Y = 0.3921X. The slope between elongation and tensile strength of the second flexible polyurethane foam layer with medium hiss is given by relation (b) Y = 0.5579X. The slope between elongation and tensile strength of the third flexible polyurethane foam layer with high hiss is given by relation (c) Y = 0.3179X. The slope between elongation and tensile strength of the third flexible polyurethane foam layer with high hiss is smaller than that of the other layers (low hiss, medium hiss). Therefore, because the third flexible polyurethane foam layer with high hiss is easily stretched, it tends to sink in when the user changes position or turns over in bed, and deforms to envelop the user. Therefore, the third soft polyurethane foam layer with high hysterosity has low resilience. On the other hand, the second soft polyurethane foam layer with medium hysterosity has a greater gradient between elongation and tensile strength than the other layers (low hysterosity, high hysterosity). Therefore, the second soft polyurethane foam layer with medium hysterosity is less prone to stretching and does not easily sag when the user changes position or turns over in bed. Thus, the second soft polyurethane foam layer with medium hysterosity has sufficient resilience.

[0023] The magnitude of the slope between elongation and tensile strength of the low-hyss first soft polyurethane foam layer is smaller than that of the medium-hyss layer and larger than that of the high-hyss layer. In other words, the magnitude of the slope between elongation and tensile strength of the low-hyss first soft polyurethane foam layer lies between that of the medium-hyss layer and the high-hyss layer. By having the thickness T1 of the low-hyss first soft polyurethane foam layer account for more than 50% of the overall mattress thickness T, the feel of turning over in bed can be improved.

[0024] It is desirable that the gradient between the tensile strength and elongation of the first flexible polyurethane foam layer be 0.38 or greater. Furthermore, the first flexible polyurethane foam layer should have a 10% hardness of 30 N / 314 cm². 2 Below, the 40% hardness is 50N / 314cm 2The following is desirable. This will result in a mattress that allows for easy turning and provides a comfortable sleep.

[0025] The mattress has a firmness of 50N / 314cm (10%). 2 Ideally, the hysteresis loss rate should be 30% or less, and the total resistance to turning over should be 5300 N·° or less. A mattress that meets these conditions will have good resilience and allow for easy turning over. The preferred range for 10% firmness is 30 N / 314 cm. 2 More than 50N / 314cm 2 The following applies: The preferred range for the hysteresis loss rate is 20% to 30%. The preferred range for the total turning resistance is 5000 N·° to 5300 N·°. The measurement methods for 10% stiffness and hysteresis loss rate are as described above. The measurement method for total turning resistance will be described later.

[0026] The mattress may have bumps or irregularities on at least one of its surface or underside. The height of the bumps can be, for example, between 5 mm and 10 mm.

[0027] Mattresses are not limited to a two-layer structure; they can have three or more layers. An example of a three-layer structure is shown in Figure 3. The top layer of mattress 1 is, for example, the first soft polyurethane foam layer 2. The middle layer 4 and the bottom layer 5 use either the second soft polyurethane foam layer or the third soft polyurethane foam layer.

[0028] In Figures 1 and 3, boundaries between layers are shown to facilitate understanding that the mattress has a layered structure; however, clear boundaries are not always present. Also, the mattress may have a cover. [Examples]

[0029] The following describes embodiments of the present invention.

[0030] (Examples 1-6 and Comparative Examples 1-4) A two-layer laminate was manufactured as a mattress using the following method.

[0031] The first to third flexible polyurethane foam layers shown in Table 4 were used as the upper and lower layers for each example and comparative example. Here, the first flexible polyurethane foam layer is referred to as layer I, the second flexible polyurethane foam layer as layer II, and the third flexible polyurethane foam layer as layer III. The physical properties of the first to third flexible polyurethane foam layers I to III are shown in Table 4. Layers I to III are products of Toyo Quality One Co., Ltd. The types of layers used are shown in the (A) upper layer urethane and (B) lower layer urethane columns of Tables 2 and 3. The thicknesses of the upper and lower layers, and the ratio of the thickness T1 of the first flexible polyurethane foam layer I to the thickness T of the mattress (T1 / T) are also shown in Tables 2 and 3.

[0032] [Table 2]

[0033] [Table 3]

[0034] [Table 4]

[0035] The upper and lower layers were bonded together using an adhesive called Bond WG320R, manufactured by Konishi Corporation, to create a laminated structure.

[0036] The resulting laminates were subjected to measurements of 10% hardness, 40% hardness, 50% deflection load, hysteresis loss rate, total resistance to turning over, and sleeping comfort. The results are shown in Tables 2 and 3. The 50% deflection load (N) was measured according to the method specified in JIS K 6400-2 (Method E):2012. Sleeping comfort was confirmed by sensory evaluation. In the sensory evaluation of sleeping comfort, a double circle was used if four or more out of five subjects liked it, a circle (〇) if three or more liked it, and a triangle (△) if two or fewer liked it.

[0037] The method for measuring the total resistance to turning over in bed will be explained with reference to Figures 4 to 7. Figure 4 shows the apparatus 10 used for measuring the total resistance to turning over in bed. A sample (mattress) 12 is placed on the base 11 of the apparatus 10. Assume that the thickness direction of the sample 12 is parallel to the z-axis direction. The dimensions of the sample 12 were 900 mm in length in the x-axis direction and 600 mm in length in the y-axis direction. An elliptical cylindrical rotating body 13 is placed on the sample 12. The rotating body 13 moves horizontally on the sample 12 in the x-axis direction by an arm 15 that rotates freely around an axis 14. The rotating body 13 also rotates freely around a rotation axis 16 parallel to the y-axis direction. Furthermore, the rotating body 13 and the arm 15 are capable of moving horizontally on the sample 12 in the x-axis direction.

[0038] The rotating body 13 is a model of a Japanese male. Figure 5 shows a cross-sectional view of the rotating body 13 cut perpendicular to the rotation axis 16. In the elliptical cross-section of the rotating body 13 shown in Figure 5, the major axis is 362 mm, corresponding to the width of the seated buttocks. The minor axis is 271 mm, corresponding to the diameter of the buttock thickness. The length of the rotation axis 16 of the rotating body 13 in the y-axis direction is 300 mm, corresponding to the length of the back. The weight of the rotating body was set to 30 kg (44% of the weight of the buttocks in the supine position), based on the average weight of a Japanese male in his 50s, which is 65 kg. The arrangement of the rotating body 13 shown in Figure 5 is with a rotation angle of 0 degrees, corresponding to the supine position. The arrangement of the rotating body 13 shown in Figure 6 is with a rotation angle of 90 degrees, corresponding to the lateral position.

[0039] The rolling resistance (N) was measured in 10-degree increments when the rotation angle of the rotating body 13 was changed from 0 degrees to 90 degrees, with a travel distance of 300 mm and a travel speed of 30 mm / s during a rollover from a supine to a lateral position. An example of the measurement results is shown in Figure 7. The sum of the rolling resistance (N) values ​​from a rotation angle of 0 degrees to 90 degrees is shown in Tables 2 and 3 as the total rollover resistance N·°. Tables 2 and 3 indicate that a total rollover resistance of 5300 N·° or less is marked with ○ (good) and that a value greater than 5300 N·° is marked with × (bad).

[0040] As is clear from the results in Tables 2 to 4, for the mattresses of Examples 1 to 6 where the thickness T1 of the first soft polyurethane foam layer I with low hysteresis loss accounts for 50% or more of the total thickness T, it was easy to turn over, and there were no major problems with the comfort. Also, among the mattresses of Examples 1 to 6, for Examples 1, 2, 4, and 5 where the 40% hardness is greater than 71 N / 314 cm 2 they were more comfortable than Examples 3 and 6 where the 40% hardness is 60 N / 314 cm 2 or less. Also, for Examples 1, 2, 4, and 5, the load at 50% deflection, which is an index of the initial indentation amount, was greater than that of Examples 3 and 6. Therefore, the mattresses of Examples 1, 2, 4, and 5 had less indentation when turning over and were also easy to turn over.

[0041] As is clear from the results of Example 1 and Example 5, there was no difference in turning over and comfort between Example 1 with the low hysteresis loss first soft polyurethane foam layer I arranged in the lower layer and Example 5 with the low hysteresis loss first soft polyurethane foam layer I arranged in the upper layer. In the case of a two-layer structure mattress, the soft layer collapses first, and then the hard layer collapses later. Since the first soft polyurethane foam layer collapses in the same way whether it is on the surface or the back, it is presumed that the turning resistance and comfort of Example 1 and Example 5 are comparable. The same can be said for the results of Example 3 and Example 6. All of the mattresses of Comparative Examples 1 to 4 had a large total turning resistance because the hysteresis loss rate was greater than 30%, and it was difficult to turn over.

[0042] Note that the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist thereof at the implementation stage. Also, the respective embodiments may be combined and implemented as appropriate, and in that case, the combined effects can be obtained. Furthermore, the above embodiments include various inventions, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiments, if the problem can be solved and the effects can be obtained, the configuration from which these constituent elements are deleted can be extracted as an invention. [Explanation of Symbols]

[0043] 1... Mattress, 2... Soft polyurethane foam layer, 3... Soft polyurethane foam layer, 4... Intermediate layer, 5... Bottom layer, 10... Apparatus, 11... Base, 12... Sample (mattress), 13... Rotating body, 14... Axis, 15... Arm, 16... Rotating axis.

Claims

1. A mattress comprising a first soft polyurethane foam layer having a hysteresis loss rate of less than 25%, wherein the thickness of the first soft polyurethane foam layer accounts for 50% or more of the total thickness.

2. The mattress according to claim 1, further comprising at least one of a second soft polyurethane foam layer having a hysteresis loss rate of 25% or more and less than 35%, or a third soft polyurethane foam layer having a hysteresis loss rate of 35% or more.

3. The mattress according to claim 2, wherein the gradient between the tensile strength and elongation of the first flexible polyurethane foam layer is smaller than the gradient between the tensile strength and elongation of the second flexible polyurethane foam layer, or larger than the gradient between the tensile strength and elongation of the third flexible polyurethane foam layer.

4. 10% hardness: 50 N / 314 cm 2 The mattress according to claim 1 or claim 2, wherein the hysteresis loss rate is 30% or less and the total resistance to turning over is 5300 N·° or less.

5. The first flexible polyurethane foam layer has a 10% hardness of 30 N / 314 cm. 2 Below, the 40% hardness is 50 N / 314 cm. 2 The mattress according to claim 1 or claim 2, wherein the slope between tensile strength and elongation is 0.38 or greater.

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