Cushion body

Abstract

To provide a cushion body having elasticity so as to be usable as an alternative to a cushion body using polyurethane foam, durability, and flexibility providing good skin touch feeling.SOLUTION: A cushion body is constituted of a first solidly crimped fiber, a second solidly crimped fiber, and a heat binder fiber. Solid crimp number of the fist solidly crimped fiber is larger than that of the second solidly crimped fiber. Single fiber fineness of the first solidly crimped fiber is smaller than that of the second solidly crimped fiber. Mixing ratio of the first solidly crimped fiber and the second solidly crimped fiber is the same or ratio of the first solidly crimped fiber is larger. Single fiber fineness of constituent fibers of the cushion body is 10 decitex or less. All the constituent fibers of the cushion body are formed of polyester having a repeating unit of ethylene terephthalate. Binder component of the heat binder fiber is made of crystalline polyester.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cushion body in which all of the constituent fibers are made of a plurality of polyester fibers having ethylene terephthalate as a repeating unit. [Background technology]

[0002] In recent years, polyurethane foams have been widely used for bedding such as mattresses and bed mats, and cushioning bodies for seat padding, cushions, and mats in sofas, chairs, automobile seats, etc., because they are inexpensive, easy to mold, and have good elasticity. However, polyurethane foams have the drawbacks of being poor in moisture permeability and prone to becoming stuffy due to their heat storage properties. They are also difficult to recycle, and when incinerated, they generate a large amount of heat and generate nitrogen-containing gases during combustion, which pose environmental problems. As a technique for solving such problems with polyurethane, the present applicant has proposed thermal bonding of the main fibers with polyester binder fibers made of a specific copolymer polyester (Patent Document 1).

[0003] According to Patent Document 1, the polyester binder fiber is a fiber made of a copolymerized polyester ether, which is a block copolymer of polyhexamethylene terephthalate as a hard segment and polytetramethylene glycol as a soft segment. The melting point of the copolymerized polyester is 100°C to 150°C, which allows the thermal bonding temperature to be set low, and provides the effect of producing textile products such as nonwoven fabrics and cushions with excellent flexibility and bending recovery at low cost. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6885588 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned Patent Document 1, nonwoven fabrics and the like having excellent flexibility and bending recovery can be obtained. However, the melting point of the thermal binder component is 100°C to 150°C. While the low melting point has the above-mentioned advantages, it is difficult to apply when heat treatment such as thermoforming is carried out in the processing step to obtain products such as cushions, and there is a risk that the cushion products will easily become worn out if they are used repeatedly at high temperatures.

[0006] To provide a cushion body that has elasticity and can be used as a substitute for cushion bodies using polyurethane foam, without causing problems in terms of recycling and the environment, which are drawbacks of polyurethane, and that also has durability and flexibility that is pleasant to the touch. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention.

[0008] That is, the present invention provides a cushion body having first three-dimensionally crimped fibers, second three-dimensionally crimped fibers, and thermal binder fibers as constituent fibers, The number of three-dimensional crimps of the first three-dimensional crimped fiber is greater than the number of three-dimensional crimps of the second three-dimensional crimped fiber; The single fiber fineness of the first three-dimensionally crimped fiber is smaller than the single fiber fineness of the second three-dimensionally crimped fiber; The mixing ratio of the first three-dimensional crimped fiber and the second three-dimensional crimped fiber in the cushion body is the same or the ratio of the first three-dimensional crimped fiber is larger, The single fiber fineness of the constituent fibers of the cushion body is 10 decitex or less, All of the constituent fibers of the cushion body are made of polyester having ethylene terephthalate as a repeating unit, The cushion body is characterized in that the binder component of the thermal binder fiber is composed of crystalline polyester, and the constituent fibers are thermally bonded to each other by the binder component. [Effects of the Invention]

[0009] According to the present invention, the constituent fibers are all composed of polyesters with ethylene terephthalate as a repeating unit, and are composed of fibers mainly composed of two specific types of three-dimensionally crimped fibers and specific thermal binder fibers. This makes it possible to provide a cushion that is durable, feels good against the skin, is flexible, and has elasticity at least equal to that of polyurethane foam. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view photograph (magnification: 30x) of the second three-dimensionally crimped fiber used in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below.

[0012] The cushion body of the present invention is composed of a mixture of first 3D crimped fibers, second 3D crimped fibers, and thermal binder fibers, each of which has a single fiber fineness of 10 dtex or less, and which is made of polyester containing ethylene terephthalate as a repeating unit, and which is thermally bonded to itself by the binder component of the thermal binder fibers. In consideration of the flexibility and feel of the cushion body, it is preferable that the single fiber fineness of each of the constituent fibers be 6 dtex or less.

[0013] In the present invention, two types of three-dimensionally crimped fibers with different three-dimensional crimp morphologies are used as main fibers (fibers that form the framework of the cushion body).

[0014] First, regarding the number of three-dimensional crimps of the two types of three-dimensional crimped fibers, the first three-dimensional crimped fiber has a higher number of three-dimensional crimps than the second three-dimensional crimped fiber.Furthermore, regarding the single fiber fineness, the first three-dimensional crimped fiber has a smaller single fiber fineness than the second three-dimensional crimped fiber.

[0015] That is, the first 3D crimped fiber has a small number of finer 3D crimps, exhibiting a spiral coil-shaped 3D crimp, and the number of 3D crimps is preferably 50 to 150 per 25 mm. The single fiber fineness of the first 3D crimped fiber is preferably 3 dtex or less. The lower limit of the single fiber fineness is preferably about 1 dtex. By having the single fiber fineness of the first 3D crimped fiber be 3 dtex or less, it is possible to more effectively exhibit a large number of fine spiral coil-shaped 3D crimps, resulting in a fiber with good flexibility. Furthermore, the first 3D crimped fiber, which has a large number of fine 3D crimps and exhibits a spiral coil-shaped 3D crimp, has a good feel on the skin and is flexible, thereby imparting excellent flexibility to the cushion body. In addition, it exhibits fine spiral coil-shaped three-dimensional crimps, and each fiber has spaces formed by the spiral coils, so when the cushion body is compressed, it plays a role in absorbing and dispersing the compression force.

[0016] Specific examples of the first 3D crimped fiber that exhibits such fine and numerous helical coil-shaped 3D crimps include side-by-side composite fibers of polyethylene terephthalate and a copolyester in which other components are copolymerized into the repeating units of ethylene terephthalate, such as a copolyester in which 0 to 9 mol % of isophthalic acid and 3 to 11 mol % of an ethylene oxide adduct of bisphenol A are copolymerized into the repeating units of ethylene terephthalate. Other examples of the copolyester include a copolyester in which 3 to 6 mol % of 5-sodium sulfoisophthalic acid is copolymerized into the repeating units of ethylene terephthalate. Furthermore, the latent crimpable conjugate fiber disclosed in Japanese Patent No. 6,591,765 of the present applicant may be used as the first three-dimensionally crimped fiber. This latent crimpable conjugate fiber is made of two types of polyester bonded side-by-side or eccentric core-sheath configuration, one of the two types of polyester being a polyester elastomer composed of hard segments and soft segments, the hard segment being a copolymer polyester in which ethylene terephthalate as the main repeating unit is copolymerized with isophthalic acid and an ethylene oxide adduct of bisphenol A, the soft segment being polytetramethylene glycol, and the other polyester being polyethylene terephthalate or a polyester mainly composed of polyethylene terephthalate.

[0017] As the first 3D crimped fiber, a fiber capable of latent 3D crimping, which manifests the coiled 3D crimp of the microcrimp by heat treatment, is preferred because it is easy to handle when producing a cushioning material. The fiber capable of latent 3D crimping (latently crimpable fiber) only exhibits mechanical crimp when mixed with the second 3D crimped fiber or thermal binder fiber to produce a web. After mixing to produce a web, the latent 3D coiled crimping ability can be manifested by heat treatment. Heat treatment may be applied solely to manifest the coiled 3D crimp of the microcrimp, but it is also preferred to manifest the coiled 3D crimp during a thermal bonding process that melts the binder component of the thermal binder fiber, as this improves production efficiency. It is preferable to use as the first three-dimensional crimped fiber a latent crimping fiber that manifests 50 or more coil-shaped three-dimensional crimps per 25 mm when heat-treated at 200°C for 15 minutes (relaxed state).

[0018] In the present invention, the second 3D crimped fiber exhibits gentle, large-diameter 3D crimps, with loop-shaped 3D crimps twisted in the fiber axis direction. Fig. 1 shows a side-view photograph (30x magnification) of the second 3D crimped fiber used in Example 1 of the present invention, which shows wavy and loop-shaped 3D crimps twisted in the fiber axis direction. The number of 3D crimps in the second 3D crimped fiber is preferably 5 to 20 per 25 mm. The single fiber fineness of the second 3D crimped fiber is preferably 4 to 10 dtex, more preferably 4 to 6 dtex. By having a single fiber fineness of 4 dtex or more, the second three-dimensionally crimped fiber has appropriate rigidity, and even when a large load such as compression is applied, the gentle and large three-dimensional crimp shape can be maintained without deformation, thereby providing the cushion body with shape retention and shape retention, and allowing for a cushion body with no bottoming out feeling, good resilience, and high bulk. It is also preferable that the second three-dimensionally crimped fiber is a hollow fiber having a hollow portion near the center of the fiber cross section. The apparent fiber diameter becomes larger, resulting in a larger diameter three-dimensional crimp and excellent rigidity.

[0019] The three-dimensional crimp of the second three-dimensionally crimped fiber has a large diameter and moderate rigidity, so that the three-dimensional crimp is unlikely to deform when mixed with other fibers or when forming a web. Therefore, it is preferable that the fiber has three-dimensional crimp at the stage of mixing with other fibers. However, if the fiber already has three-dimensional crimp, the three-dimensional crimp of the second three-dimensionally crimped fiber may change somewhat during the heat bonding treatment after web formation or the heat treatment for actualizing the latent three-dimensional crimp of the first three-dimensionally crimped fiber, as long as it is within the scope of the present invention.

[0020] A specific example of the second three-dimensionally crimped fiber, which exhibits such gentle, large-diameter, loop-shaped three-dimensional crimps twisted in the fiber axis direction, is a composite fiber in which two polyethylene terephthalates having different viscosities are combined side-by-side. The viscosity difference (intrinsic viscosity difference) between the two polyethylene terephthalates is preferably about 0.1 to 0.2. The second three-dimensionally crimped fiber exhibits three-dimensional crimp during the fiber production stage due to the viscosity difference between the polyethylene terephthalates being combined. Unlike the first three-dimensionally crimped fiber described above, the second three-dimensionally crimped fiber exhibits three-dimensional crimps in the form of loops twisted in the fiber axis direction when mixed with other fibers to form a web. Furthermore, in order to blend well with other fibers, it is preferable that the second three-dimensionally crimped fiber have both three-dimensional crimp and mechanical crimp. In addition, in order to maintain the gentle three-dimensional crimp of the second three-dimensionally crimped fiber without breaking it down, it is preferable that the mechanical crimping is imparted by gear processing rather than by a press-in crimper.

[0021] The second 3D crimped fiber can be obtained as follows: Two types of polyethylene terephthalate having the above-mentioned difference in intrinsic viscosity are melt-spun using a side-by-side composite nozzle, taken up at a take-up speed of 1000 to 1200 m / min, hot-drawn at a drawing temperature of about 290°C to a total draw ratio of 2.5 to 3.5, and then subjected to a relaxation heat treatment and gear processing to develop 5 to 20 3D crimps per 25 mm of loops twisted in the fiber axis direction, and then cut to the desired length within the range of 15 to 80 mm to obtain the second 3D crimped fiber.

[0022] It is preferable that the mixing ratio of the first 3D crimped fibers and the second 3D crimped fibers in the cushion body be the same or that the ratio of the first 3D crimped fibers be higher. This makes it possible to obtain a cushion body that is soft against the skin, has good absorption and dispersion of compression force, and is resistant to settling. In other words, if the ratio of the second 3D crimped fibers that exhibit large diameter 3D crimps is high, more voids will be created in the cushion body, and although bulkiness will be improved, the cushion body will become somewhat hard and will not absorb and disperse stress well, which is not what is desired in the present invention. By using the same ratio of the first crimped fibers as the second crimped fibers, or by using a larger ratio of the first crimped fibers, the first crimped fibers can penetrate the gaps between the larger-diameter crimps of the second crimped fibers, creating a structure in which the two types of crimped fibers support each other, preventing the gaps in the cushion from becoming too large, resulting in a cushion that is resistant to wear and deformation even with repeated use, and that has good skin feel and flexibility.The mixing ratio (mass ratio) of the first crimped fibers to the second crimped fibers is preferably 1 to 4 / 1.

[0023] The cushion body of the present invention contains, in addition to the two main types of 3D crimped fibers described above, 10 to 30 mass% of thermal binder fibers. Since the constituent fibers of the cushion body of the present invention, the first 3D crimped fibers, the second 3D crimped fibers, and the thermal binder fibers, are all made of polyesters having ethylene terephthalate as a repeating unit, the cushion body of the present invention has good heat resistance and excellent recyclability. Furthermore, unlike urethane cushions, it does not generate nitrogen-containing gases upon combustion, making it preferable from an environmental standpoint.

[0024] The thermal binder fiber's binder component thermally bonds the constituent fibers together, integrating them into a cushion and maintaining its shape. Because the binder component is made of crystalline polyester, heat resistance is improved. Furthermore, because both of the two types of three-dimensionally crimped fibers are polyester-based, compatibility with the binder component is excellent, resulting in high adhesive strength. Therefore, even when repeatedly compressed with a large force, the adhesive strength at the thermally bonded points is high and the thermally bonded points are resistant to separation, resulting in a cushion that is resistant to settling and deformation even over long periods of time. Furthermore, because the binder component is made of crystalline polyester, the adhesive strength at the thermally bonded points is maintained, and there is little change in shape, making it resistant to settling and deformation, even when used at high temperatures.

[0025] The single fiber fineness of the thermal binder fiber is preferably 3 to 6 dtex. When the single fiber fineness of the thermal binder fiber is 3 dtex or more, the number of contact points between the constituent fibers and the thermal binder fiber is not too many, and the number of thermally bonded points is also not too many, resulting in a cushion body that is pleasant to the touch and has excellent flexibility. On the other hand, when the single fiber fineness is 6 dtex or less, the number of thermally bonded points is not too few, and the constituent fibers are well bonded to each other, allowing the shape of the cushion body to be maintained.

[0026] The reason why the mixed amount of thermal binder fibers is preferably 10 to 30% by mass is the same as above. When the mixed amount is 10% by mass or more, the number of thermally bonded points is not too small, and the constituent fibers can be well bonded to each other, and the shape of the cushion can be maintained. When the mixed amount is 30% by mass or less, the number of thermally bonded points is not too large, and the cushion has a good feel and excellent flexibility.

[0027] Specifically, thermal binder fibers are fibers that contain crystalline copolymerized polyesters formed by copolymerizing ethylene terephthalate repeating units with other components as the thermal binder component, with the thermal binder component present on the fiber surface. Examples of other components copolymerized with the ethylene terephthalate units include 10 to 25 mol% isophthalic acid. Other examples of such components include copolymerized 1,4-butanediol and diethylene glycol. In the present invention, the thermal binder component is preferably a copolymerized polyester consisting of four components: terephthalic acid, ethylene glycol, 1,4-butanediol, and diethylene glycol, and has a melting point of 160 to 210°C. In this case, the molar ratios of the diol components are preferably 8.0 to 79.5 mol% ethylene glycol, 20.0 to 90.0 mol% 1,4-butanediol, and 0.5 to 2.0 mol% diethylene glycol. This range results in a melting point of approximately 180 to 210°C. In addition to the four components described above, ε-caprolactone may be copolymerized. The copolymerization ratio of ε-caprolactone is 5.0 to 20.0 mol %, and copolymerization of ε-caprolactone results in a melting point of the thermal binder component of approximately 140°C to 200°C. The thermal binder fiber may be a single-phase fiber consisting of only the thermal binder component, or a core-sheath fiber consisting of polyethylene terephthalate in the core and the thermal binder component in the sheath. Single-phase thermal binder fibers lose their fibrous form and become the thermal adhesive component upon thermal bonding treatment, resulting in a cushion body that feels good against the skin and has excellent flexibility. With core-sheath thermal binder fibers, the core remains after thermal bonding treatment, maintaining its fibrous form, while only the sheath becomes the thermal adhesive component. Because the core remains, shape retention is improved.

[0028] The fiber length of the fibers constituting the cushion body of the present invention may be selected as appropriate, but in consideration of ease of mixing and ease of web formation, it is preferably in the range of 15 to 80 mm.

[0029] The cushion body of the present invention can be obtained by the following method. First, the constituent fibers are prepared. The main fibers are the first 3D crimped fibers and the second 3D crimped fibers described above. The 3D crimp of the first 3D crimped fibers is manifested and expressed during the cushion body manufacturing process. Therefore, latent crimp fibers with latent crimping properties that will become the first 3D crimped fibers are prepared. The latent crimping fibers with latent crimping properties that will become the first 3D crimped fibers, the second 3D crimped fibers, and thermal binder fibers are weighed in the desired ratio, and then defibrated and blended in a carding machine to form a blended web. Multiple sheets of this blended web are stacked as needed and heat-treated while being regulated to the desired thickness and shape. If necessary, prior to heat treatment, the blended web or a laminated web made up of multiple sheets may be subjected to a needle punching process or the like to entangle the fibers that make up the web or the laminated webs. The heat treatment temperature is set to a temperature at which the binder component melts (approximately 180 to 220°C), melting or softening the binder component to thermally bond the constituent fibers together and promoting the expression of the latent crimp of the latent crimpable fibers that will become the first 3D crimped fibers, thereby manifesting the 3D crimp and obtaining a cushion body. Note that, for efficiency, it is preferable to perform the heat treatment step for melting or softening the binder component and the heat treatment step for manifesting the 3D crimp of the first 3D crimped fibers simultaneously, but they may also be performed sequentially in separate steps.

[0030] The cushion body of the present invention is durable, feels good against the skin, and is flexible. 2 It is suitable for bedding such as mattresses and bed mats, and sofas, which have a large basis weight. It is also suitable for seat padding, cushions, and mats for chairs, car seats, etc., which are repeatedly compressed during use. Furthermore, it is suitable for use in a mattress having a basis weight of 80 to 800 g / m. 2 It can also be suitably used for padding for various clothing items with a basis weight of about 100%, padding for protectors, etc. Furthermore, since it is easily recyclable, it can also be used as various sound absorbing materials, heat insulating materials, and thermal insulating materials. [Example]

[0031] Next, the present invention will be specifically described using examples. Example 1 The first 3D crimped fiber was a latent crimp fiber (single fiber fineness 2.8 dtex, fiber length 51 mm, mechanical crimps 12 / 25 mm using a press crimper) made by combining polyethylene terephthalate and a copolymer polyester obtained by copolymerizing 5 mol% of 5-sodium sulfoisophthalic acid with repeating units of ethylene terephthalate in a side-by-side configuration. This latent crimped fiber was subjected to dry heat treatment in a relaxed state at 200°C for 15 minutes to develop coil-shaped 3D crimps of 78 / 25 mm. The second three-dimensional crimped fiber is a hollow fiber made by compounding high-viscosity polyethylene terephthalate and low-viscosity polyethylene terephthalate in a side-by-side manner, and is a three-dimensional crimped fiber (manufactured by Unitika Ltd.) in which 11 three-dimensional crimps are generated per 25 mm. <h38x>A single fiber (fiber size 4.4 decitex, fiber length 64 mm) was prepared.

[0032] As the thermal binder fiber, a core-sheath type thermal binder fiber (single fiber fineness 4.4 decitex, fiber length 51 mm, mechanical crimped by a press crimper 11 crimps / 25 mm) was prepared. The core was made of polyethylene terephthalate and the sheath was made of a copolymer polyester (melting point 180°C) consisting of four components: terephthalic acid, ethylene glycol, 1,4-butanediol, and diethylene glycol.

[0033] The latent crimp fiber that becomes the first three-dimensional crimp fiber, the second three-dimensional crimp fiber, and the thermal binder fiber were mixed in a mass ratio of 60:20:20 using a random carding machine to prepare a web. The prepared web (basis weight: approximately 400 g / m 2 Four sheets of the 3D crimped fiber were stacked on top of each other, and the stacked web was sandwiched and fixed between punching plates with a thickness of 40 mm. The web was then treated for 4 minutes in a continuous heat treatment machine set at 200°C, and then allowed to cool at room temperature to obtain a cushion body. The heat treatment at 200°C caused the constituent fibers to be thermally bonded together, and the latent crimp of the latent crimpable fibers that would become the first 3D crimped fibers became apparent, resulting in the development of fine, coil-like 3D crimps.

[0034] Example 2 A cushion body was obtained in the same manner as in Example 1, except that the mixing ratio (mass ratio) of the constituent fibers was 40:40:20: latent crimping fiber that becomes the first three-dimensional crimping fiber:second three-dimensional crimping fiber:thermal binder fiber.

[0035] Example 3 A cushion body was obtained in the same manner as in Example 1, except that a core-sheath type thermal binder fiber (single fiber fineness 4.4 decitex, fiber length 51 mm, mechanical crimping by a press crimper 11 crimps / 25 mm) was prepared as the thermal binder fiber, in which polyethylene terephthalate was used as the core and a copolymer polyester (melting point 160°C) consisting of five components: terephthalic acid, ethylene glycol, 1,4-butanediol, diethylene glycol, and ε-caprolactone was used as the sheath.

[0036] Example 4 A cushion body was obtained in the same manner as in Example 1, except that the second three-dimensionally crimped fiber was a solid fiber composed of a side-by-side composite of high-viscosity polyethylene terephthalate and low-viscosity polyethylene terephthalate, with three-dimensional crimps of 10 per 25 mm (Unitika Ltd. <38X>, single fiber fineness 3.3 dtex, fiber length 51 mm).

[0037] Example 5 A cushion body was obtained in the same manner as in Example 1, except that the following were used as the latently crimpable fibers that would become the first three-dimensional crimped fibers and the second three-dimensional crimped fibers.

[0038] The first 3D crimped fiber was a latent crimp fiber (single fiber fineness 2.8 dtex, fiber length 51 mm, mechanical crimps 11 / 25 mm using a press crimper) made by combining polyethylene terephthalate and a copolymer polyester copolymerized with 4.0 mol% isophthalic acid and 4.5 mol% ethylene oxide adduct of bisphenol A with ethylene terephthalate repeat units in a side-by-side configuration. This latent crimped fiber exhibited 120 coil-shaped 3D crimps / 25 mm after dry heat treatment in a relaxed state at 200°C for 15 minutes.

[0039] As the second three-dimensionally crimped fiber, the second three-dimensionally crimped fiber used in Example 4 was prepared.

[0040] Comparative Example 1 In Example 1, the second three-dimensionally crimped fiber was a solid fiber made of a side-by-side composite of high-viscosity polyethylene terephthalate and low-viscosity polyethylene terephthalate, with three-dimensional crimps of 7 per 25 mm (manufactured by Unitika Ltd.). <mph>A cushion body was obtained in the same manner as in Example 1, except that a single fiber (fiber size: 14 dtex, fiber length: 51 mm) was prepared.

[0041] Comparative Example 2 Instead of the latent crimp fiber that would become the first three-dimensional crimped fiber, a single-phase fiber consisting of only polyethylene terephthalate without latent crimping properties (single fiber fineness 18 dtex, fiber length 51 mm, mechanical crimping by a press crimper 10 crimps / 25 mm) was prepared as the main fiber. The second three-dimensional crimped fiber is a solid fiber made of a side-by-side composite of high-viscosity polyethylene terephthalate and low-viscosity polyethylene terephthalate, and is a three-dimensional crimped fiber (manufactured by Unitika Ltd.) that exhibits 7 three-dimensional crimps per 25 mm. <mph>A single fiber fineness of 14 decitex and a fiber length of 51 mm was prepared. A cushion body was obtained in the same manner as in Example 1 except for the above.

[0042] The obtained cushion bodies (Examples 1 to 5, Comparative Examples 1 and 2) were measured for various characteristic values ​​as follows.

[0043] Weight (g / m 2 ): Ten samples of 100 mm x 100 mm square were cut out from the obtained cushion body (solid cotton), and the weight of each was measured. The width of the roll was taken as 100 and the weight of each was calculated as the basis weight. The average of these 10 samples was then taken as the basis weight.

[0044] Thickness (mm): For 10 samples prepared with the above-mentioned basis weight, a load of 1.96 KPa was applied, and after 10 minutes the thickness of the center was measured. The thickness of each sample was recorded as T0 (mm) with a rounded width of 10, and the average value of these 10 samples was taken as the thickness.

[0045] Stress at initial 40% compression (N): Samples were prepared by cutting out 100mm x 100mm squares from the obtained cushion body (solid cotton), and these samples were subjected to 200 cycles of 40% compression at room temperature using a compression tester (a cyclic compression tester manufactured by TMT Corporation) under the following conditions: compression frequency 170 cycles / min, initial load 5N, test load 1000N, compression speed 20mm / min. The stress applied at 40% compression after 200 cycles was recorded as the initial stress at 40% compression.

[0046] Stress change rate after repeated compression (80,000 times): Samples were cut out from the resulting cushion body (solid cotton) to prepare 100mm x 100mm squares. These samples were subjected to 80,000 cycles of 40% compression using a compression tester (a cyclic compression tester manufactured by TMT Corporation) at room temperature under the following conditions: compression frequency: 170 cycles / min, initial load: 5N, test load: 1000N, compression speed: 20mm / min. The stress applied at 40% compression after 80,000 cycles was measured. The stress S0 at 40% compression after 200 cycles (initial stress at 40% compression) and the stress S1 after 80,000 cycles were used to calculate the rate of change in stress after repeated compression (80,000 cycles) using the following formula: Stress change rate after repeated compression (80,000 times) = [(S0-S1) / S0] x 100

[0047] Thickness change rate after repeated compression (80,000 times): The thickness of the test specimen after measuring the rate of change in stress after repeated compression (80,000 times) was measured by the method described in (2) Thickness. The rate of change in thickness after repeated compression was calculated using the following formula using the initial thickness T0 (mm) and the thickness T1 (mm) after 80,000 compressions. Thickness change rate after repeated compression (80,000 times) = [T0-T1) / T0] x 100

[0048] The evaluation results are shown in Table 1.

[0049] [Table 1]

[0050] The 40% compressive stress of a 40 mm thick polyurethane foam used in commercially available bed mats is approximately 250 N, so the cushion body of the present invention had a soft texture equivalent to or even softer than polyurethane foam. Furthermore, the 40% compressive stress change rate and thickness change rate after 80,000 compressions were small, indicating excellent durability.< / mph> < / mph>

Claims

1. A cushion body having first three-dimensionally crimped fibers, second three-dimensionally crimped fibers, and thermal binder fibers as constituent fibers, The number of three-dimensional crimps of the first three-dimensional crimped fiber is greater than the number of three-dimensional crimps of the second three-dimensional crimped fiber; The single fiber fineness of the first three-dimensionally crimped fiber is smaller than the single fiber fineness of the second three-dimensionally crimped fiber; The mixing ratio of the first three-dimensional crimped fiber and the second three-dimensional crimped fiber in the cushion body is the same or the ratio of the first three-dimensional crimped fiber is larger, The single fiber fineness of each of the constituent fibers of the cushion body is 10 decitex or less, All of the constituent fibers of the cushion body are made of polyester having ethylene terephthalate as a repeating unit, A cushion body characterized in that the binder component of the thermal binder fiber is composed of crystalline polyester, and the constituent fibers are thermally bonded to each other by the binder component.

2. 2. The cushion body according to claim 1, wherein the single fiber fineness of the first three-dimensionally crimped fiber is 3 dtex or less, and the single fiber fineness of the second three-dimensionally crimped fiber is 4 dtex or more.

3. 3. The cushion body according to claim 1 or 2, wherein the three-dimensional crimp of the first three-dimensional crimped fiber is a coil-shaped three-dimensional crimp, and the three-dimensional crimp of the second three-dimensional crimped fiber is a loop-shaped three-dimensional crimp twisted in the fiber axis direction.

4. The cushion body according to claim 3, characterized in that the coil-shaped three-dimensional crimps of the first three-dimensional crimped fiber are a manifestation of latent crimping ability, with the number of three-dimensional crimps being 50 to 150 per 25 mm, and the number of three-dimensional crimps of the second three-dimensional crimped fiber being 5 to 20 per 25 mm.

5. 3. The cushion body according to claim 1, wherein the thermal binder fiber is mixed in the cushion body in an amount of 10 to 30% by mass, and the single fiber fineness of the thermal binder fiber is 3 to 6 decitex.

6. The cushion body according to claim 1 or 2, characterized in that the thermal binder component of the thermal binder fiber is a crystalline polyester having a melting point of 160°C to 210°C, and is composed of a copolymer having terephthalic acid, 1,4-butanediol, ethylene glycol, and diethylene glycol as constituent components.

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