Three-dimensional net-like structure

Abstract

Provided is a three-dimensional net-like structure that plays a role in supporting a body when a localized load is applied to an end region, and that is unlikely to impart a sense of discomfort due to a difference in hardness from a central region when the localized load is not applied, such as when a user unconsciously moves to the end region due to turning over or the like during sleeping. In this three-dimensional network structure 1, the apparent density of an end region 20 is higher than the apparent density of a central region 10 by 30% or more. The end region 20 has an inner layer part 21 that is to the inside in a thickness direction z of the three-dimensional network structure 1, and surface layer parts 22 respectively positioned on both sides of the inner layer part 21 in the thickness direction z. The difference between the apparent density of the inner layer part 21 and the apparent density of the central region 10 is 20% or less, the difference between the 25% compressive hardness of the end region 20 and the 25% compressive hardness of the central region 10 is 10% or less, and the 50% compressive hardness of the end region 20 is higher than the 50% compressive hardness of the central region 10 by 15% or more.

Description

Three-dimensional mesh structure

[0001] This invention relates to a three-dimensional mesh structure.

[0002] Currently, three-dimensional mesh structures are being widely used as cushioning materials for furniture, bedding such as beds, and seats in vehicles such as trains, automobiles, and motorcycles. Compared to foamed and cross-linked polyurethane, three-dimensional mesh structures have comparable durability, superior moisture permeability and breathability, and less heat retention, making them less prone to stuffiness. Furthermore, three-dimensional mesh structures are made of thermoplastic resin, making them easy to recycle, free from concerns about residual chemicals, and environmentally friendly. In recent years, there has been a demand for materials with varying hardness depending on the part, in order to further enhance their functionality as cushioning materials used in bedding and pillows.

[0003] Among these, a specific request regarding hardness design is for mattresses that use a three-dimensional mesh structure, which have a high-hardness area at the periphery, including both ends in the width direction of the mattress, to allow users such as hospitalized patients and those requiring care to sit down and get out of bed with stability.

[0004] In response to the above-mentioned demands, Patent Document 1 discloses a mattress that includes a central block positioned in the center of the mattress in the width direction and end blocks positioned at both ends, wherein the end blocks are harder than the central block, thereby improving stability when sitting on the end and when getting up, as well as improving ease of turning over in bed. Furthermore, Patent Document 2 discloses a cushion body for a pillow in which the resilience of the regions at both ends in the width direction is higher than that of the central region, and the resilience of the regions at both ends in the depth direction is higher than that of the central region, and which is capable of stabilizing the head position while allowing the head to sink in appropriately.

[0005] Utility Model Registration No. 3228060, International Publication No. 2022 / 097435

[0006] In the aforementioned Patent Document 1, cushioning materials with different hardness levels are used in the central and both ends in the width direction, and the hardness level at the point of contact with the user's shoulders is further adjusted by providing multiple grooves in the mattress. In Patent Document 2, a cushioning body is disclosed in which hardness levels are formed at both ends in the width direction by changing the apparent density of a three-dimensional filament bond. However, in mattresses made using either of the cushioning material hardness-changing means described in Patent Documents 1 and 2, there is a problem that when a user unconsciously moves to the hardness level at the periphery while sleeping, they may experience discomfort due to the difference in hardness between the central and periphery, potentially disrupting their sleep.

[0007] Therefore, there is a need for a cushioning material that can support large localized loads at the edges of the mattress, such as when sitting on the mattress or getting out of bed with weight on one hand, while also minimizing discomfort due to differences in hardness between the central and edge areas when the user unconsciously moves to the edge area during sleep, thus not disrupting sleep.

[0008] Specifically, with conventional cushioning materials as shown in Figures 3 and 4, while firmly supporting localized heavy loads such as sitting on the edge areas or getting out of bed, a cushioning material was needed that would not cause a difference in hardness between the edge areas and the central area when no localized heavy loads were applied, such as when lying down during sleep, as shown in Figure 4. However, it was difficult to achieve these conflicting properties simultaneously with conventional technology.

[0009] The present invention aims to provide a three-dimensional mesh structure that supports the body when a localized load is applied to the end region, and that minimizes discomfort due to differences in hardness between the central and end regions when no localized load is applied, such as when the user unconsciously moves to the end region due to turning over in their sleep.

[0010] As a result of diligent research to solve the above-mentioned problems, the inventors have found that by making the apparent density of the end regions of a three-dimensional mesh structure higher than the apparent density of the central region, the structure can support the body when a localized load is applied to the end regions, while by making the apparent density of the inner layer located inside the thickness direction of the end regions equivalent to or close to that of the central region, a three-dimensional mesh structure can be obtained that does not cause discomfort due to the difference in hardness between the central region and the end regions when no localized load is applied, such as when the user unconsciously moves to the end region by turning over in their sleep. In other words, the present invention is as follows. [1] A three-dimensional mesh structure comprising a continuous linear body made of a thermoplastic resin composition and having a three-dimensional random loop joint structure, comprising a central region located in the center in the width direction of the three-dimensional mesh structure, and end regions located on both sides of the central region in the width direction, wherein the apparent density of the end regions is 30% or more higher than the apparent density of the central region, the end regions comprising an inner layer located inside in the thickness direction of the three-dimensional mesh structure, and surface layers located on both sides of the inner layer in the thickness direction, the difference between the apparent density of the inner layer and the apparent density of the central region is 20% or less, the difference between the 25% compressive hardness of the end regions and the 25% compressive hardness of the central region is 10% or less, and the 50% compressive hardness of the end regions is 15% or more higher than the 50% compressive hardness of the central region. [2] The three-dimensional mesh structure according to [1], wherein the end region has an outer edge on the end opposite to the side where the central region is located, and the apparent density of the outer edge is 30% or more higher than the apparent density of the central region. [3] The three-dimensional mesh structure according to [2], wherein the outer edge constitutes the end in the width direction of the three-dimensional mesh structure. [4] The three-dimensional mesh structure according to [2] or [3], wherein in the width direction of the three-dimensional mesh structure, the length of the outer edge is shorter than the length of the inner layer and the length of the surface layer. [5] The three-dimensional mesh structure according to any one of [1] to [4], wherein the thickness of the inner layer is greater than the thickness of the surface layer.[6] The three-dimensional mesh structure according to any one of [1] to [5], wherein the length of the central region in the width direction of the three-dimensional mesh structure is longer than the length of the end regions in the width direction of the three-dimensional mesh structure. [7] The three-dimensional mesh structure according to any one of [1] to [6], wherein the difference between the average fiber diameter of the continuous linear bodies in the central region and the average fiber diameter of the continuous linear bodies in the end regions is 0.20 mm or less. [8] The three-dimensional mesh structure according to any one of [1] to [7], wherein the number of bonding points per unit weight of the continuous linear bodies in the surface layer is greater than the number of bonding points per unit weight of the continuous linear bodies in the central region. [9] The three-dimensional mesh structure according to any one of [1] to [8], wherein the thermoplastic resin composition constituting the continuous linear bodies contains a polyester thermoplastic elastomer.

[0011] In this invention, the apparent density of the end regions is 30% or more higher than the apparent density of the central region, the difference between the apparent density of the inner layer and the apparent density of the central region is 20% or less, the difference between the 25% compressive hardness of the end regions and the 25% compressive hardness of the central region is 10% or less, and the 50% compressive hardness of the end regions is 15% or more higher than the 50% compressive hardness of the central region. As a result, a three-dimensional mesh structure can be made that has suitable compressive hardness for supporting the body when localized loads such as sitting on the end regions are applied, and that does not impede the user's sleeping comfort. This excellent balance of hardness makes it possible to provide a three-dimensional mesh structure suitable as a cushioning material used not only in bedding and mattresses, but also in office chairs, furniture, sofas, beds and other bedding, and seats for vehicles such as trains, automobiles and motorcycles.

[0012] This diagram shows schematic representations of the three-dimensional mesh structures in Examples 1 and 4 of the present invention. This diagram shows schematic representations of the three-dimensional mesh structures in Example 2 of the present invention. This diagram shows schematic representations of the three-dimensional mesh structures in Comparative Example 2 of the present invention. This diagram shows a schematic representation of an example of the usage state of the three-dimensional mesh structure in Comparative Example 2 of the present invention. This diagram shows schematic representations of the nozzle used in the manufacture of the three-dimensional mesh structure in Example 1 of the present invention. This diagram shows schematic representations of the nozzle used in the manufacture of the three-dimensional mesh structure in Example 2 of the present invention. This diagram shows schematic representations of the nozzle used in the manufacture of the three-dimensional mesh structure in Example 4 of the present invention.

[0013] Hereinafter, the present invention will be specifically described with reference to the drawings. However, the present invention is not limited to the illustrated examples, and it is also possible to appropriately modify and implement it within the scope that conforms to the gist of the foregoing and following descriptions, and all of them are included in the technical scope of the present invention.

[0014] The three-dimensional network structure of the present invention is a three-dimensional network structure composed of continuous linear bodies made of a thermoplastic resin composition and having a three-dimensional random loop joining structure. It has a central region located at the center in the width direction of the three-dimensional network structure, and end regions located on both sides of the central region in the width direction. The apparent density of the end region is 30% or more higher than the apparent density of the central region. The end region has an inner layer portion inside in the thickness direction of the three-dimensional network structure, and surface layer portions located on both sides of the inner layer portion in the thickness direction. The difference between the apparent density of the inner layer portion and the apparent density of the central region is 20% or less. The difference between the 25% compression hardness in the end region and the 25% compression hardness in the central region is 10% or less. The 50% compression hardness in the end region is 15% or more higher than the 50% compression hardness in the central region.

[0015] The three-dimensional network structure of the present invention is composed of continuous linear bodies made of a thermoplastic resin composition and has a three-dimensional random loop joining structure. Specifically, the continuous linear bodies made of a thermoplastic resin composition are bent and twisted to form random loops, and the continuous linear bodies are brought into contact with each other and the contact portions are fused to form a three-dimensional three-dimensional network structure. Therefore, even if a large deformation is given to the three-dimensional network structure with a very large stress, the entire three-dimensional network structure composed of the fused and integrated three-dimensional random loops can be deformed to absorb the stress. Also, when the stress is released, the three-dimensional network structure can be restored to its original form by the elastic force of the thermoplastic resin.

[0016] The thermoplastic resin composition is not particularly limited as long as it can be bent and twisted to bring the continuous linear bodies into contact with each other and fuse the contact portions between the continuous linear bodies. Examples include polyester-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and thermoplastic ethylene vinyl acetate copolymer elastomers. Among these, the thermoplastic resin composition is preferably a thermoplastic elastomer, and more preferably a polyester-based thermoplastic elastomer because it has excellent compressive durability and heat resistance.

[0017] Examples of polyester-based thermoplastic elastomers include polyester ether block copolymers in which thermoplastic polyester is the hard segment and polyalkylenediol is the soft segment, or polyester ester block copolymers in which aliphatic polyester is the soft segment.

[0018] The polyester ether block copolymer is an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, and diphenyl-4,4'-dicarboxylic acid; an alicyclic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid; an aliphatic dicarboxylic acid such as succinic acid, adipic acid, and sebacate dimer acid; or at least one dicarboxylic acid selected from these ester-forming derivatives, and 1,4-butanediol, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethic acid Examples include ternary block copolymers composed of at least one diol component selected from aliphatic diols such as ethylene glycol and hexamethylene glycol, alicyclic diols such as 1,1-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, or ester-forming derivatives thereof, and at least one polyalkylenediol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or glycol made from ethylene oxide-propylene oxide copolymer, having a number average molecular weight of about 300 to 5000.

[0019] Examples of the polyester - ester block copolymer include a ternary block copolymer composed of at least one of the above - mentioned dicarboxylic acids, diols, and polyester diols such as polylactone having a number - average molecular weight of about 300 to 5000. Considering thermal adhesiveness, hydrolysis resistance, stretchability, heat resistance, etc., as the dicarboxylic acid, terephthalic acid and / or naphthalene - 2,6 - dicarboxylic acid are preferred; as the diol component, 1,4 - butanediol is preferred; as the polyalkylene diol, a ternary block copolymer of polytetramethylene glycol, or as the polyester diol, a ternary block copolymer of polylactone is preferred. In special examples, those with a polysiloxane - based soft segment introduced can also be used.

[0020] Also, in the polyester - ester copolymer, it is particularly preferred that the dicarboxylic acid is terephthalic acid and / or naphthalene - 2,6 - dicarboxylic acid, the diol component is 1,4 - butanediol, and the polyester diol is composed of polylactone to form a ternary block copolymer. In special examples, those with a polysiloxane - based soft segment introduced can also be used.

[0021] Further, those obtained by blending a non - elastomer component with the above - mentioned polyester - based thermoplastic elastomer, copolymerizing them, using a polyolefin - based component as the soft segment, etc. are also included in the polyester - based thermoplastic elastomer of the present invention. Additionally, those obtained by adding various additives, etc. to the polyester - based thermoplastic elastomer as needed are also included.

[0022] The continuous linear body constituting the three - dimensional network structure of the present invention may be a composite linear body combined with other thermoplastic resins within a range not impairing the object of the present invention. Examples of the composite form include, when the linear body itself is made composite, composite linear bodies such as sheath - core type, side - by - side type, and eccentric sheath - core type.

[0023] To achieve suitable compressive hardness in the end regions of the three-dimensional mesh structure, which is the objective of the present invention, the soft segment content of the polyester thermoplastic elastomer is preferably 15% by weight or more, more preferably 25% by weight or more, even more preferably 30% by weight or more, and particularly preferably 40% by weight or more. For ensuring hardness and heat resistance and deformation resistance, it is preferably 80% by weight or less, more preferably 70% by weight or less.

[0024] Various additives can be added to the thermoplastic elastomer of the continuous linear body constituting the three-dimensional network structure of the present invention, depending on the purpose. Possible additives include plasticizers such as phthalate esters, trimellitic acid esters, fatty acid esters, epoxy esters, adipic acid esters, and polyesters; antioxidants such as known hindered phenols, sulfurs, phosphorus, and amines; light stabilizers such as hindered amines, triazoles, benzophenones, benzoates, nickel, and salicyls; antistatic agents; molecular weight modifiers such as peroxides; compounds having reactive groups such as epoxy compounds, isocyanate compounds, and carbodiimide compounds; metal deactivators; organic and inorganic nucleating agents, neutralizing agents, antacids, antibacterial agents, fluorescent whitening agents, fillers, flame retardants, flame retardant aids, and organic and inorganic pigments.

[0025] The average fiber diameter of the continuous linear members constituting the three-dimensional mesh structure of the present invention is preferably 0.1 mm or more and 3.0 mm or less. An average fiber diameter of 0.1 mm or more ensures an appropriate thickness for the continuous linear members, thereby securing the necessary hardness for the three-dimensional mesh structure. Furthermore, an average fiber diameter of 3.0 mm or less results in a finer three-dimensional random loop joint structure of the three-dimensional mesh structure, improving compressive durability.

[0026] The cross-sectional shape of the continuous linear members constituting the three-dimensional mesh structure of the present invention is not particularly limited, but for example, by using a hollow cross-section or an irregularly shaped cross-section, desirable compressibility and a good feel can be provided.

[0027] The thickness of the three-dimensional mesh structure of the present invention is preferably 20 mm or more, more preferably 25 mm or more, and even more preferably 30 mm or more. The thickness of the three-dimensional mesh structure refers to the average value of the thickness of the central region 10 and the thickness of the end regions 20 of the three-dimensional mesh structure. A thickness of 20 mm or more of the three-dimensional mesh structure makes it less likely for the three-dimensional mesh structure to feel like it is touching the floor. Furthermore, the upper limit of the thickness of the three-dimensional mesh structure is preferably 300 mm or less, more preferably 200 mm or less, and even more preferably 120 mm or less, due to the limitations of the manufacturing equipment.

[0028] As shown in Figures 1 and 2, the central region 10 refers to the region located in the center of the three-dimensional mesh structure 1 in the width direction x, and is a band-shaped portion. The end regions 20 refer to the portions that extend in a band shape from the periphery of the three-dimensional mesh structure 1 toward the center, and are intended to support the user's body and ensure stability during use. The end regions 20 are located on both sides of the central region 10 in the width direction x of the three-dimensional mesh structure 1. The length direction y of the three-dimensional mesh structure 1 is preferably the longitudinal direction of the three-dimensional mesh structure 1, and the width direction x is preferably perpendicular to the length direction y. Furthermore, the length direction y of the three-dimensional mesh structure 1 is preferably the direction from head to toe when the user lies on the three-dimensional mesh structure 1, and the width direction x is preferably the left-right direction when the user lies on the three-dimensional mesh structure 1.

[0029] The width of the end region 20 is preferably 10 cm or more in order to ensure the stability of body support when the user is seated. The end region 20 may be provided in either the width direction x or the length direction y of the three-dimensional mesh structure 1, or both. Furthermore, the width, length, and position of the end region 20 can be determined appropriately according to the application of the three-dimensional mesh structure 1. For example, in the case of a chair cushion, there is a need to make the part located at the thighs firmer, so the width of the end region 20 is preferably 15 cm or more. Also, in the case of a mattress, there is a need to make the part located at the shoulders firmer, so the width of the end region 20 is preferably 30 cm or more. Furthermore, in the case of a seated mattress, there is a need to make the edges of the mattress firmer, so the width of the end region 20 is preferably 10 cm or more.

[0030] The apparent density of the end region 20 is 30% or more higher than the apparent density of the central region 10. In other words, the difference in apparent density between the end region 20 and the central region 10 is 30% or more. The apparent density of the end region 20 refers to the overall apparent density of the end region 20, including the inner layer 21 and the surface layer 22. Similarly, the apparent density of the central region 10 refers to the overall apparent density of the central region 10. Because the apparent density of the end region 20 is 30% or more higher than the apparent density of the central region 10, sufficient hardness necessary for user support can be ensured.

[0031] The apparent density of the end region 20 is preferably 35% or more higher than the apparent density of the central region 10, more preferably 40% or more higher, and still more preferably 45% or more higher. By setting the lower limit value of the difference in apparent density between the end region 20 and the central region 10 within the above range, it is possible to easily increase the hardness of the end region 20 compared to the central region 10. Further, when the apparent density of the end region 20 is higher than the apparent density of the central region 10, the difference in apparent density between the end region 20 and the central region 10 is preferably 75% or less, more preferably 70% or less, and still more preferably 65% or less. By setting the upper limit value of the difference in apparent density between the end region 20 and the central region 10 within the above range, it is possible to prevent the hardness of the central region 10 and the end region 20 from being excessively different, and to reduce the sense of discomfort due to the difference in hardness between the central region 10 and the end region 20.

[0032] The apparent density of the central region 10 is preferably 0.005 g / cm ３ or more, more preferably 0.010 g / cm ３ or more, and still more preferably 0.020 g / cm ３ or more. By setting the lower limit value of the apparent density of the central region 10 within the above range, it is possible to impart appropriate hardness to the central region 10 and make it easier to support the user's body. Further, the apparent density of the central region 10 is preferably 0.150 g / cm ３ or less, more preferably 0.130 g / cm ３ or less, and still more preferably 0.100 g / cm ３ or less. By setting the upper limit value of the apparent density of the central region 10 within the above range, the flexibility of the central region 10 is increased, and it is possible to obtain the three-dimensional network structure 1 with good cushioning properties.

[0033] The apparent density of the end region 20 is preferably 0.010 g / cm ３ or more, more preferably 0.030 g / cm ３ or more, and still more preferably 0.050 g / cm ３It is even more preferable that the above conditions are met. By setting the lower limit of the apparent density of the end region 20 to the above range, the hardness of the end region 20 can be increased, resulting in a three-dimensional mesh structure 1 that can easily support the user's body. Furthermore, the apparent density of the end region 20 is 0.200 g / cm³. ３ Preferably, it is 0.180 g / cm³. ３ It is more preferable that the following is the case: 0.150 g / cm³ ３ It is even more preferable that the following conditions are met: By setting the upper limit of the apparent density of the end region 20 within the above range, it is possible to prevent the end region 20 from becoming too hard and to prevent the weight of the three-dimensional mesh structure 1 from becoming too heavy.

[0034] As shown in Figures 1 and 2, the end region 20 has an inner layer 21 located inside the three-dimensional mesh structure 1 in the thickness direction z, and surface layers 22 located on both sides of the inner layer 21 in the thickness direction z. The inner layer 21 refers to the central part when the surface perpendicular to the thickness direction z of the three-dimensional mesh structure 1 is considered the surface layer 22. In other words, in the thickness direction z of the three-dimensional mesh structure 1, the surface layers 22, the inner layer 21, and the surface layer 22 are arranged in that order from the front to the back of the three-dimensional mesh structure 1. To put it another way, in the thickness direction z of the three-dimensional mesh structure 1, the inner layer 21 is located between the two surface layers 22.

[0035] The difference between the apparent density of the inner layer 21 and the apparent density of the central region 10 is 20% or less. In other words, the inner layer 21 and the central region 10 have similar apparent densities. The difference between the apparent density of the inner layer 21 and the apparent density of the central region 10 refers to the ratio of the difference in apparent density between the inner layer 21 and the central region 10. Because the difference between the apparent density of the inner layer 21 and the apparent density of the central region 10 is 20% or less, the end region 20 in the thickness direction z of the three-dimensional mesh structure 1 has an inner layer 21 with an apparent density similar to that of the central region 10. The method for measuring the difference between the apparent density of the inner layer 21 and the apparent density of the central region 10 will be described later.

[0036] The difference between the apparent density of the inner layer 21 and the apparent density of the central region 10 is preferably 15% or less, more preferably 12% or less, and even more preferably 10% or less. By setting the upper limit of the difference between the apparent density of the inner layer 21 and the apparent density of the central region 10 within the above range, the apparent density of the inner layer 21 and the apparent density of the central region 10 can be brought closer to the same level. Alternatively, there may be no difference between the apparent density of the inner layer 21 and the apparent density of the central region 10; that is, the apparent density of the inner layer 21 and the apparent density of the central region 10 may be the same.

[0037] The apparent density of the surface layer 22 is preferably higher than the apparent density of the inner layer 21. Furthermore, the apparent density of the surface layer 22 is preferably higher than the apparent density of the central region 10. In other words, the apparent density of the surface layer 22 is preferably higher than the apparent density of the inner layer 21 and the central region 10. By having a surface layer 22 with a higher apparent density than the inner layer 21 and the central region 10, the hardness of the edge region 20 can be increased compared to the central region 10.

[0038] The difference between the 25% compressive hardness in the end region 20 and the 25% compressive hardness in the central region 10 is 10% or less, and the 50% compressive hardness in the end region 20 is 15% or more higher than the 50% compressive hardness in the central region 10. 25% compressive hardness refers to the stress at 25% compression in the stress-strain curve obtained by compressing the corresponding region (end region 20 or central region 10) of the three-dimensional mesh structure 1 to 75% of its initial thickness using a circular compression plate with a diameter of φ200 mm. The difference between the 25% compressive hardness in the end region 20 and the 25% compressive hardness in the central region 10 refers to the ratio of the difference in 25% compressive hardness between the end region 20 and the central region 10. The method for measuring the difference between the 25% compressive hardness in the end region 20 and the 25% compressive hardness in the central region 10 will be described later. 50% compression hardness refers to the stress at 50% compression in the stress-strain curve obtained by compressing the corresponding region (end region 20 or central region 10) of the three-dimensional mesh structure 1 to 50% of its initial thickness using a circular compression plate with a diameter of φ200 mm.

[0039] The difference between the 25% compression hardness in the end region 20 and the 25% compression hardness in the central region 10 is 10% or less. This means that when a user lies on the three-dimensional mesh structure 1 and no localized load is applied, they will not feel much difference in hardness between the end region 20 and the central region 10. When a user moves from the central region 10 to the end region 20 while sleeping, for example, the discomfort caused by the difference in hardness will be reduced, improving sleeping comfort. Preferably, the difference between the 25% compression hardness in the end region 20 and the 25% compression hardness in the central region 10 is 8% or less, and more preferably 5% or less.

[0040] On the other hand, if the 50% compression hardness in the end region 20 is 15% or more higher than that in the central region 10, then when a large localized load is applied, such as when the user sits on the end region 20 or gets out of bed, the load can be firmly supported and the user's body can be supported, reducing the risk of the user falling or tipping over. It is preferable that the 50% compression hardness in the end region 20 is 20% or more higher than that in the central region 10. There is no particular upper limit, but for example, the 50% compression hardness in the end region 20 is higher than that in the central region 10, and the difference in 50% compression hardness between the end region 20 and the central region 10 is 50% or less.

[0041] In the present invention, the difference between the 25% compressive hardness in the end region 20 and the 25% compressive hardness in the central region 10 is 10% or less, while the 50% compressive hardness in the end region 20 is 15% or more higher than the 50% compressive hardness in the central region 10. This is thought to be because, at 25% compression, the inner layer 21, which has an apparent density similar to that of the central region 10, is compressed more than the surface layer 22, resulting in a difference of 10% or less between the 25% compressive hardness in the end region 20 and the 25% compressive hardness in the central region 10. At 50% compression, not only the inner layer 21 but also the surface layer 22 is compressed, causing the 50% compressive hardness in the end region 20 to be 15% or more higher than the 50% compressive hardness in the central region 10. As a result, when no localized load is applied, such as during sleep, the difference in hardness between the end region 20 and the central region 10 is not easily felt. However, when a large localized load is applied, such as when sitting on the end region 20 or getting out of bed, the end region 20 can support the load and support the user's body.

[0042] The 25% compressive hardness in the end region 20 and the 25% compressive hardness in the central region 10 are preferably 5 N / φ200 or higher, more preferably 15 N / φ200 or higher, and even more preferably 25 N / φ200 or higher. By setting the lower limit of the 25% compressive hardness in the end region 20 and the central region 10 within the above range, the three-dimensional mesh structure 1 can have an appropriate hardness and sufficient cushioning performance. Furthermore, the 25% compressive hardness in the end region 20 and the 25% compressive hardness in the central region 10 are preferably 500 N / φ200 or lower, more preferably 300 N / φ200 or lower, and even more preferably 100 N / φ200 or lower. By setting the upper limit of the 25% compressive hardness in the end region 20 and the central region 10 within the above range, it is possible to prevent the three-dimensional mesh structure 1 from becoming excessively hard and to improve the cushioning properties of the three-dimensional mesh structure 1.

[0043] The 50% compressive hardness in the end region 20 and the 50% compressive hardness in the central region 10 are preferably 10 N / φ200 or higher, more preferably 20 N / φ200 or higher, and even more preferably 30 N / φ200 or higher. By setting the lower limit of the 50% compressive hardness in the end region 20 and the central region 10 within the above range, the feeling of bottoming out of the three-dimensional mesh structure 1 can be reduced and the cushioning performance can be improved. Furthermore, the 50% compressive hardness in the end region 20 and the 50% compressive hardness in the central region 10 are preferably 1000 N / φ200 or lower, more preferably 600 N / φ200 or lower, and even more preferably 200 N / φ200 or lower. By setting the upper limit of the 50% compressive hardness in the end region 20 and the central region 10 within the above range, the three-dimensional mesh structure 1 can be made flexible, resulting in a three-dimensional mesh structure 1 with good cushioning performance.

[0044] As shown in Figure 1, in the end region 20, it is preferable that the outer edge portion 23 is located at the end opposite to the side where the central region 10 is located, and that the apparent density of the outer edge portion 23 is 30% or more higher than the apparent density of the central region 10. In other words, it is preferable that the end region 20 has the outer edge portion 23 at the end of the portion where the inner layer portion 21 and the surface layer portion 22 are stacked in the width direction x of the three-dimensional mesh structure 1. To put it another way, in the end region 20, it is preferable that the surface layer portion 22 and the outer edge portion 23, which have a higher apparent density than the inner layer portion 21, are located in a U-shape on the upper surface, lower surface and the end surface opposite to the side where the central region 10 is located. The end portion 20 has an outer edge portion 23 on the side opposite to the central portion 10, which has an apparent density 30% or more higher than the central portion 10. This allows the outer edge portion 23 to also contribute to supporting the user's body, enabling the development of high rigidity when a load is applied in the thickness direction z. Therefore, it is easier to ensure sufficient rigidity to support the body when a localized load is applied to the end of the three-dimensional mesh structure 1, and the risk of tipping or falling can be sufficiently suppressed. In addition, the surface smoothness of the three-dimensional mesh structure 1 can be ensured, which improves sleeping comfort and makes it easier to insert into a cover or fabric.

[0045] The apparent density of the outer edge portion 23 is preferably 30% or more higher than the apparent density of the central region 10, more preferably 40% or more higher, even more preferably 50% or more higher, even more preferably 60% or more higher, particularly preferably 70% or more higher, and most preferably 80% or more higher. By setting the lower limit of the difference in apparent density between the outer edge portion 23 and the central region 10 within the above range, it becomes easier to increase the hardness of the outer edge portion 23 compared to the central region 10. Furthermore, when the apparent density of the outer edge portion 23 is higher than the apparent density of the central region 10, the difference in apparent density between the outer edge portion 23 and the central region 10 is preferably 250% or less, more preferably 200% or less, even more preferably 150% or less, even more preferably 120% or less, particularly preferably 110% or less, and most preferably 100% or less. By setting the upper limit of the difference in apparent density between the outer edge 23 and the central region 10 relative to the apparent density of the central region 10 to the above range, the hardness of the central region 10 and the hardness of the edge region 20 will not differ significantly, and the sense of discomfort caused by the difference in hardness between the central region 10 and the edge region 20 will be reduced.

[0046] The apparent density of the outer edge 23 is 0.020 g / cm³. ３ Preferably, it is 0.040 g / cm³ or more. ３ It is more preferable that the concentration be greater than or equal to 0.060 g / cm³. ３ It is even more preferable that the above conditions are met. By setting the lower limit of the apparent density of the outer edge portion 23 within the above range, the rigidity of the end region 20 is increased by the outer edge portion 23, making it easier to support the user's body. Furthermore, the apparent density of the outer edge portion 23 is 0.220 g / cm³. ３ Preferably, it is 0.200 g / cm³. ３ It is more preferable that the following is the case: 0.180 g / cm³ ３ It is even more preferable that the following conditions are met: By setting the upper limit of the apparent density of the outer edge portion 23 within the above range, it is possible to prevent the outer edge portion 23 of the end region 20 from becoming too hard, and to prevent the weight of the end region 20 from increasing, thereby increasing the overall weight of the three-dimensional mesh structure 1.

[0047] As shown in Figure 1, it is preferable that the outer edge portion 23 constitutes the end of the three-dimensional mesh structure 1 in the width direction x. By having the outer edge portion 23 constitute the end of the three-dimensional mesh structure 1, the hardness of the end of the three-dimensional mesh structure 1 is increased, making it easier to support the user's body when a localized load is applied to the end of the three-dimensional mesh structure 1.

[0048] Although not shown in the figures, the outer edge portion 23 may constitute the end of the three-dimensional mesh structure 1 in the longitudinal direction y. By having the outer edge portion 23 constitute the end of the three-dimensional mesh structure 1 in the longitudinal direction y, it becomes possible to increase the hardness of the end in the longitudinal direction y by the outer edge portion 23.

[0049] As shown in Figure 1, in the width direction x of the three-dimensional mesh structure 1, it is preferable that the length L23 of the outer edge portion 23 is shorter than the length L21 of the inner layer portion 21 and the length L22 of the surface layer portion 22. In the width direction x, when the length L23 of the outer edge portion 23 is shorter than the length L21 of the inner layer portion 21 and the length L23 of the outer edge portion 23 is shorter than the length L22 of the surface layer portion 22, the discomfort caused by the difference in hardness between the outer edge portion 23 and the central region 10 can be further reduced when a user lies down on the three-dimensional mesh structure 1 and touches the outer edge portion 23.

[0050] As shown in Figures 1 and 2, it is preferable that the thickness T21 of the inner layer 21 is greater than the thickness T22 of the surface layer 22. By making the thickness T21 of the inner layer 21 greater than the thickness T22 of the surface layer 22, the proportion of the end region 20 in which the inner layer 21 is present can be increased. As a result, the difference in 25% compression hardness between the end region 20 and the central region 10 can be made smaller, further reducing the difference in hardness between the central region 10 and the end region 20 when a user lies on the three-dimensional mesh structure 1, thereby reducing the discomfort caused by the difference in hardness. Note that "thickness T22 of the surface layer 22" refers to the thickness of the surface layer 22 provided on one side of the inner layer 21. Figures 1 and 2 show a three-dimensional mesh structure in which the thickness of the surface layers 22 on both sides is the same, but if the thicknesses of the surface layers 22 on both sides are different, it is preferable that the thickness of the inner layer 21 is greater than the thickness of either of the surface layers 22 on both sides.

[0051] The length L10 of the central region 10 in the width direction x of the three-dimensional mesh structure 1 is preferably longer than the length L20 of the end regions 20 in the width direction x of the three-dimensional mesh structure 1. By making the length L10 of the central region 10 longer than the length L20 of the end regions 20 in the width direction x of the three-dimensional mesh structure 1, the proportion of the central region 10 present in the width direction x of the three-dimensional mesh structure 1 can be increased, resulting in a flexible and cushioned three-dimensional mesh structure 1. Note that "length L20 of the end regions 20" refers to the length of the end region 20 provided on one side of the central region 10. Figures 1 and 2 show a three-dimensional mesh structure in which the lengths of the end regions 20 on both sides are the same. However, if the lengths of the end regions 20 on both sides are different, it is preferable that the length of the central region 10 is greater than the thickness of either of the lengths of the end regions 20 on both sides.

[0052] The difference between the average fiber diameter of the continuous linear material in the central region 10 and the average fiber diameter of the continuous linear material in the end region 20 is preferably 0.20 mm or less, more preferably 0.10 mm or less, and even more preferably 0.05 mm or less. By setting the upper limit of the difference in the average fiber diameter of the continuous linear material in the central region 10 and the end region 20 to the above range, it becomes less likely that a large difference in 25% compression hardness will occur between the central region 10 and the end region 20.

[0053] Preferably, the number of joints per unit weight of the continuous linear body in the surface layer 22 is greater than the number of joints per unit weight of the continuous linear body in the central region 10. A greater number of joints in the surface layer 22 than in the central region 10 increases the hardness of the surface layer 22 compared to the central region 10, making it easier to support the user's body when a localized load is applied in the end region 20.

[0054] A joint point refers to a point where a continuous linear body intersects and is joined. The number of joint points per unit weight (points / g) can be measured by the following method. First, the three-dimensional mesh structure 1 is cut into a rectangular parallelepiped shape, and in the resulting rectangular parallelepiped pieces, the number of joint points per unit volume (points / cm³) in each piece is measured. ３ ) and apparent density of individual pieces (g / cm³)３ The number of joints per unit weight (joints / g) can be determined by measuring the number of joints and dividing the number of joints by the apparent density. The number of joints can be determined by pulling apart two continuous linear bodies joined at a joint point and measuring the number of times this separation occurs. Note that the apparent density of the three-dimensional mesh structure 1 in the length direction y or width direction x is 0.005 g / cm³. ３ In cases where there is a band-like difference in density as described above, it is preferable to cut the material into a rectangular parallelepiped shape such that the boundary line between the dense and sparse parts becomes the midpoint in the length or width direction of the individual pieces, and then determine the number of joining points per unit weight (pieces / g).

[0055] In addition, in all of the embodiments described later, the thickness T21 of the inner layer 21 is greater than the thickness T22 of the surface layer 22, the length L10 of the central region 10 is longer than the length L20 of the end region 20, and the number of joints per unit weight of the continuous linear body of the surface layer 22 is greater than the number of joints per unit weight of the continuous linear body of the central region 10.

[0056] This application claims the benefit of priority based on Japanese Patent Application No. 2024-171409, filed on 30 September 2024, and Japanese Patent Application No. 2024-190635, filed on 30 October 2024. The entire contents of the specifications of Japanese Patent Application No. 2024-171409, filed on 30 September 2024, and Japanese Patent Application No. 2024-190635, filed on 30 October 2024, are incorporated herein by reference.

[0057] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and can be implemented with modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of the present invention.

[0058] <Characteristics of the Three-Dimensional Mesh Structure> (1) Average Fiber Diameter (mm) A sample of the three-dimensional mesh structure was cut to a size of 10 cm in width x 10 cm in length x sample thickness, and 10 continuous linear samples of approximately 5 mm in length were randomly collected from the cut surface. The collected continuous linear samples were cut in the cross-sectional direction, placed upright in the direction of the fiber axis on a coverslip, and cross-sectional fiber images were obtained using an optical microscope set to an appropriate magnification. The diameter of the fibers was determined from the obtained cross-sectional fiber images, and the average value of 10 samples in the end region was taken as the average fiber diameter in the end region, and the average value of 10 samples in the central region was taken as the average fiber diameter in the central region (unit: mm). In addition, the average value of the above 10 samples in the end region and the above 10 samples in the central region (average value of 20 samples) was calculated and taken as the average fiber diameter of the entire three-dimensional mesh structure (unit: mm). The surface of the three-dimensional mesh structure is flattened to achieve smoothness, and the shape of the fiber cross-section may be deformed. Therefore, samples of continuous linear fibers were not taken from within 2 mm of the surface of the three-dimensional mesh structure. In cases where the cross-sectional shape of the continuous linear fiber was hollow or irregular, the outer circumference of the cross-sectional shape of the continuous linear fiber was determined from the obtained fiber cross-sectional photographs. The diameter of a circle with an outer circumference equal to that length was calculated and defined as the fiber diameter.

[0059] (2) Thickness (mm), apparent density (g / cm³) ３ ) and end-to-center density difference ratio (%) From a sample of a three-dimensional mesh structure, four samples were cut from the end region with dimensions of 10 cm in width, 10 cm in length, and sample thickness, and left unloaded for 24 hours. After that, an area of ​​15 cm² was measured using a Polymer Instruments FD-80N thickness gauge. ２ Using a circular measuring probe, the thickness of each sample was measured at one point, and the average value of the four samples was calculated to determine the thickness of the end region (unit: mm). If the fiber diameter of the continuous linear material differed between the front and back surfaces in the thickness direction of the three-dimensional mesh structure, the sample thickness was measured with the side with the thinner fiber diameter facing upwards. Furthermore, the mass of each sample was measured using an electronic balance, and the average value of the four samples was calculated to determine the mass of the end region (unit: g). The apparent density of the end region (unit: g / cm³) was also calculated.３ The apparent density (g / cm³) was calculated from the measured mass and thickness using the following formula. Furthermore, four samples were cut from the central region of the three-dimensional mesh structure, each measuring 10 cm in width, 10 cm in length, and the sample thickness. The thickness and apparent density of the end regions were calculated using the same method as for the end regions. Additionally, the average value of the four end region samples and the four central region samples was calculated and used as the overall thickness of the three-dimensional mesh structure (hereinafter sometimes referred to as "average thickness"). The density difference ratio between the end regions and the central region (end-central density difference ratio) was calculated using the following formula: Apparent density (g / cm³) ３ ) = Mass (g) / (Thickness (cm) × 10 (cm) × 10 (cm)) End-to-center density difference ratio (%) = (Apparent density of end region - Apparent density of center region) / Apparent density of center region × 100

[0060] (3) Apparent density of the inner layer (g / cm³) ３ ) and central-to-inner layer density difference ratio (%) A sample was cut from the three-dimensional mesh structure to a size of 5 cm in width x 5 cm in length x sample thickness (the sample thickness corresponds to the thickness of the three-dimensional mesh structure), and the thickness of the sample was measured in the same manner as in (2) above. Next, the sample was cut at points 0.5 cm away from the surface and back surfaces in the thickness direction, and the total mass (g) of the remaining sample was divided by the volume ((sample thickness (cm) - (0.5 (cm) × 2)) × 5 (cm) × 5 (cm)) to obtain the apparent density of the inner layer (g / cm³). ３ The density difference ratio between the central region and the inner layer (central region - inner layer density difference ratio) was calculated using the following formula: Central region - inner layer density difference ratio (%) = (Apparent density of high-density area - Apparent density of low-density area) / Apparent density of central region × 100 In the above formula, the apparent density of the high-density area is the apparent density of the higher-density area between the central region and the inner layer, and the apparent density of the low-density area is the apparent density of the lower-density area between the central region and the inner layer.

[0061] (4) Apparent density at the outer edge (g / cm³) ３) and the density difference ratio (%) of the outer edge to the center A sample was cut from the three-dimensional mesh structure sample with dimensions of 5 cm in width, 5 cm in length, and sample thickness (sample thickness corresponds to the thickness of the three-dimensional mesh structure), including the outer edge, and the thickness of the sample was measured in the same manner as in (2) above. Next, a sample of the outer edge was further cut from the sample cut from the three-dimensional mesh structure sample with dimensions of 0.5 cm in width, 5 cm in length, and sample thickness, and the apparent density (g / cm) of the outer edge sample was divided by the volume (0.5 (cm) × 5 (cm) × sample thickness (cm)) to obtain the apparent density (g / cm) of the outer edge. ３ The density difference ratio between the outer edge and central region (outer edge - central region density difference ratio) was calculated using the following formula: Outer edge - central region density difference ratio (%) = (Apparent density of the outer edge - Apparent density of the central region) / Apparent density of the central region × 100

[0062] (5) 25% Compression Hardness Difference Ratio (N / φ200) A rectangular parallelepiped shape was cut from the end region of the three-dimensional mesh structure sample, measuring 10 cm in width and 10 cm in length, including the surface and back surface in the thickness direction of the three-dimensional mesh structure, but not including the edges of the three-dimensional mesh structure. The stress-strain curve obtained by compressing the sample to 75% using a φ200 mm compression plate manufactured by Orientec Co., Ltd. is expressed as the stress at 25% compression (unit: N / φ200). The average value of the stresses in the three samples was used as the 25% compression hardness of the end region. The central region was also cut into a rectangular parallelepiped shape in the same way as the end region, and the average value of the stresses in the three samples was used as the 25% compression hardness of the central region. The ratio of the 25% compression hardness difference between the end region and the central region (unit: %) was calculated using the 25% compression hardness of each region measured by the method described above, using the following formula. 25% Compression Hardness Difference Ratio (%) = (25% Compression Hardness of High-Hardness Area - 25% Compression Hardness of Low-Hardness Area) / 25% Compression Hardness of Low-Hardness Area × 100 In the above formula, the 25% compression hardness of the high-hardness area is the 25% compression hardness of the area with the higher 25% compression hardness between the end region and the central region, and the 25% compression hardness of the low-hardness area is the 25% compression hardness of the area with the lower 25% compression hardness between the end region and the central region.

[0063] (6) 50% Compression Hardness (N / φ200) A rectangular parallelepiped shape was cut from the end region of the three-dimensional mesh structure sample, measuring 10 cm in width and 10 cm in length, including the surface and back surface in the thickness direction of the three-dimensional mesh structure, but not including the edges of the three-dimensional mesh structure. The stress-strain curve obtained by compressing the sample to 75% using a φ200 mm compression plate manufactured by Orientec Co., Ltd. is expressed as the stress at 50% compression (unit: N / φ200). The average value of the stresses in the three samples was used as the 50% compression hardness of the end region. The central region was also cut into a rectangular parallelepiped shape in the same way as the end region, and the average value of the stresses in the three samples was used as the 50% compression hardness of the central region. The ratio of the difference in 50% compression hardness between the end region and the central region (unit: %) was calculated using the 50% compression hardness of each region measured by the method described above, using the following formula. 50% Compression Hardness Difference Ratio (%) = (50% Compression Hardness of the Edge Region - 50% Compression Hardness of the Central Region) / 50% Compression Hardness of the Central Region × 100

[0064] [Example 1] Dimethyl terephthalate (DMT) and 1,4-butanediol (1,4-BD) were charged with a small amount of catalyst as a polyester thermoplastic elastomer. After transesterification by a conventional method, polytetramethylene glycol (PTMG) with a number average molecular weight of 1000 was added, and polycondensation was carried out under increased temperature and reduced pressure to produce a polyether ester block copolymer elastomer. Then, 1% by mass of an antioxidant was added, mixed and kneaded, and pelletized. The mixture was then vacuum dried at 50°C for 48 hours to obtain thermoplastic resin composition A-1. Thermoplastic resin composition A-1 had a soft segment content of 40% by mass and a melting point of 198°C.

[0065] Using a nozzle with an effective surface length of 900 mm in the width direction and 35 mm in the thickness direction, 5.0 mm diameter orifices were arranged in a staggered pattern with a hole pitch of 9 mm, and the pore density was increased along the outer peripheral edge of the end region as shown in Figure 5. The obtained thermoplastic resin composition A-1 was discharged downward from the nozzle at a nozzle temperature (spinning temperature) of 240°C at a single-hole discharge rate of 4.75 g / min. After passing through a cooling space with an ambient temperature of 30°C, without blowing cooling air, cooling water was placed 42 cm below the nozzle surface, and a pair of pull-up conveyors were placed parallel to a 150 cm wide stainless steel endless net with an opening width of 34 mm apart, partially above the water surface. The molten continuous linear material was bent and twisted to form loops, fusing the contact parts and forming a three-dimensional random loop joint structure. The molten three-dimensional mesh structure described above was pulled into cooling water at a speed of 2.85 m / min while being sandwiched between two conveyors to solidify and flatten both sides. After that, it was cut to a predetermined size and dried with hot air at 110°C for 15 minutes to obtain the three-dimensional mesh structure shown in Figure 1. The properties of the three-dimensional mesh structure made of the obtained thermoplastic resin composition are shown in Tables 1 and 2.

[0066] The resulting three-dimensional network structure is mainly composed of hollow, round-section fibers with an average fiber diameter of 0.67 mm (a difference of 0.03 mm between the end and central regions), an average thickness of 32.4 mm, and an apparent density of 0.079 g / cm³ at the end regions. ３ The apparent density in the central region is 0.049 g / cm³. ３ The apparent density at the outer edge is 0.089 g / cm³. ３ The width of the end region that constitutes the seated position was 12 cm.

[0067] For the obtained three-dimensional mesh structure, the 25% compressive hardness in the end regions was 63.1 N / φ200, and the 25% compressive hardness in the central region was 60.4 N / φ200. The 50% compressive hardness in the end regions was 134.9 N / φ200, and the 50% compressive hardness in the central region was 102.8 N / φ200. The hardness differences between the end regions and the central region at 25% and 50% compressive hardness were 4.5% and 31.2%, respectively. The results are shown in Tables 1 and 2.

[0068] [Example 2] Using a nozzle with an effective surface length of 970 mm in the width direction and 45 mm in the thickness direction, orifices with a hole diameter of 5.0 mm were arranged in a staggered pattern with a hole pitch of 9 mm, and the hole density on the upper and lower surfaces in the thickness direction was increased, excluding the side surfaces of the end regions as shown in Figure 6. The obtained thermoplastic resin composition A-1 was discharged downward from the nozzle at a nozzle temperature (spinning temperature) of 240°C at a single-hole discharge rate of 3.93 g / min. After passing through a cooling space with an ambient temperature of 30°C, cooling water was placed 42 cm below the nozzle surface without blowing cooling air, and a pair of pull conveyors were placed parallel to a 150 cm wide stainless steel endless net with an opening width of 44 mm apart so that part of them were above the water surface. The molten continuous linear body was bent and twisted to form loops, fusing the contact parts and forming a three-dimensional random loop joint structure. The molten three-dimensional mesh structure described above was pulled into cooling water at a speed of 2.85 m / min while being sandwiched between two conveyors to solidify and flatten both sides. After that, it was cut to a predetermined size and dried with hot air at 110°C for 15 minutes to obtain the three-dimensional mesh structure shown in Figure 2. The properties of the three-dimensional mesh structure made of the obtained thermoplastic resin composition are shown in Tables 1 and 2.

[0069] The resulting three-dimensional network structure is mainly composed of hollow, round-section fibers with an average fiber diameter of 0.66 mm (a difference of 0.02 mm between the end and central regions), an average thickness of 42.4 mm, and an apparent density of 0.053 g / cm³ in the end regions. ３ The apparent density in the central region is 0.035 g / cm³. ３ The apparent density at the outer edge is 0.069 g / cm³. ３ The width of the end region that constitutes the seated position was 12 cm.

[0070] For the obtained three-dimensional mesh structure, the 25% compressive hardness of the end regions was 25.5 N / φ200, and the 25% compressive hardness of the central region was 26.1 N / φ200. The 50% compressive hardness of the end regions was 61.0 N / φ200, and the 50% compressive hardness of the central region was 50.3 N / φ200. The hardness difference between the end regions and the central region at 25% and 50% compressive hardness was 2.1% and 21.4%, respectively. The results are shown in Tables 1 and 2.

[0071] [Example 3] Using a nozzle with an effective surface length of 970 mm in the width direction and 45 mm in the thickness direction, orifices with a hole diameter of 5.0 mm were arranged in a staggered pattern with a hole pitch of 9 mm, and the hole density was increased along the outer peripheral edge of the end region as shown in Figure 5. The obtained thermoplastic resin composition A-1 was discharged downward from the nozzle at a nozzle temperature (spinning temperature) of 240°C at a single-hole discharge rate of 3.93 g / min. After passing through a cooling space with an ambient temperature of 30°C, cooling water was placed 42 cm below the nozzle surface without blowing cooling air, and a pair of pull conveyors were placed parallel to a 150 cm wide stainless steel endless net with an opening width of 44 mm apart so that a portion of them was above the water surface. The molten continuous linear body was bent and twisted to form loops, fusing the contact parts together to form a three-dimensional random loop joint structure. The molten three-dimensional mesh structure described above was pulled into cooling water at a speed of 2.21 m / min while being sandwiched between two conveyors to solidify and flatten both sides. After that, it was cut to a predetermined size and dried with hot air at 110°C for 15 minutes to obtain a three-dimensional mesh structure. The properties of the three-dimensional mesh structure made of the obtained thermoplastic resin composition are shown in Tables 1 and 2.

[0072] The resulting three-dimensional network structure is mainly composed of hollow, round-section fibers with an average fiber diameter of 0.68 mm (a difference of 0.03 mm between the end and central regions), an average thickness of 42.1 mm, and an apparent density of 0.068 g / cm³ in the end regions. ３ The apparent density in the central region is 0.044 g / cm³. ３ The apparent density at the outer edge is 0.081 g / cm³. ３ The width of the end region that constitutes the seated position was 15 cm.

[0073] For the obtained three-dimensional mesh structure, the 25% compressive hardness of the end regions was 49.3 N / φ200, and the 25% compressive hardness of the central region was 48.3 N / φ200. The 50% compressive hardness of the end regions was 99.7 N / φ200, and the 50% compressive hardness of the central region was 79.4 N / φ200. The hardness difference between the end regions and the central region at 25% and 50% compressive hardness was 2.1% and 25.6%, respectively. The results are shown in Tables 1 and 2.

[0074] [Example 4] Using a nozzle with an effective surface length of 890 mm in the width direction and 65 mm in the thickness direction, orifices with a hole diameter of 5.0 mm were arranged in a staggered pattern with a hole pitch of 9 mm as the basis, and the number of rows of discharge holes was increased along the outer peripheral edge of the end region as shown in Figure 7. The obtained thermoplastic resin composition A-1 was discharged downward from the nozzle at a nozzle temperature (spinning temperature) of 240°C at a single-hole discharge rate of 3.22 g / min. After passing through a cooling space with an ambient temperature of 30°C, cooling water was placed 30 cm below the nozzle surface without blowing cooling air, and a pair of take-up conveyors were placed parallel to a 150 cm wide stainless steel endless net with an opening width of 64 mm apart so that a portion of them was above the water surface. The molten continuous linear body was bent and twisted to form loops, fusing the contact parts together to form a three-dimensional random loop joint structure, creating a three-dimensional mesh structure. The molten three-dimensional mesh structure described above was pulled into cooling water at a speed of 1.55 m / min while being sandwiched between two conveyors to solidify and flatten both sides. After that, it was cut to a predetermined size and dried with hot air at 110°C for 15 minutes to obtain the three-dimensional mesh structure shown in Figure 1. The properties of the three-dimensional mesh structure made of the obtained thermoplastic resin composition are shown in Tables 1 and 2.

[0075] The resulting three-dimensional network structure was mainly composed of hollow, round-section fibers with an average fiber diameter of 0.85 mm (there was no difference in average fiber diameter between the end and central regions), with an average thickness of 60.9 mm and an apparent density of 0.057 g / cm³ in the end regions. ３ The apparent density in the central region is 0.039 g / cm³. ３ The apparent density at the outer edge is 0.077 g / cm³. ３ The width of the end region that constitutes the seated position was 12 cm.

[0076] For the obtained three-dimensional mesh structure, the 25% compressive hardness of the end regions was 43.7 N / φ200, and the 25% compressive hardness of the central region was 43.0 N / φ200. The 50% compressive hardness of the end regions was 90.5 N / φ200, and the 50% compressive hardness of the central region was 71.5 N / φ200. The hardness difference between the end regions and the central region at 25% and 50% compressive hardness was 1.6% and 26.6%, respectively. The results are shown in Tables 1 and 2.

[0077] [Example 5] Using a nozzle with an effective surface length of 900 mm in the width direction and 25 mm in the thickness direction, orifices with a hole diameter of 5.0 mm were arranged in a staggered pattern with a hole pitch of 9 mm, and the hole density was increased along the outer peripheral edge of the end region as shown in Figure 5. The obtained thermoplastic resin composition A-1 was discharged downward from the nozzle at a nozzle temperature (spinning temperature) of 240°C at a single-hole discharge rate of 2.90 g / min. After passing through a cooling space with an ambient temperature of 30°C, cooling water was placed 42 cm below the nozzle surface without blowing cooling air, and a pair of pull-up conveyors were placed parallel to a 150 cm wide stainless steel endless net with an opening width of 23 mm apart so that part of them were above the water surface. The molten continuous linear material was bent and twisted to form loops, fusing the contact parts together to form a three-dimensional random loop joint structure, creating a three-dimensional mesh structure. The molten three-dimensional mesh structure described above was pulled into cooling water at a speed of 2.89 m / min while being sandwiched between two conveyors to solidify and flatten both sides. After that, it was cut to a predetermined size and dried with 110°C hot air for 15 minutes to obtain a three-dimensional mesh structure. The properties of the three-dimensional mesh structure made of the obtained thermoplastic resin composition are shown in Tables 1 and 2.

[0078] The resulting three-dimensional network structure was mainly composed of hollow, round-section fibers with an average fiber diameter of 0.68 mm (there was no difference in average fiber diameter between the end and central regions), an average thickness of 22.1 mm, and an apparent density of 0.054 g / cm³ in the end regions. ３ The apparent density in the central region is 0.036 g / cm³. ３ The apparent density at the outer edge is 0.070 g / cm³. ３ The width of the end region that constitutes the seated position was 30 cm.

[0079] For the obtained three-dimensional mesh structure, the 25% compressive hardness of the end regions was 25.8 N / φ200, and the 25% compressive hardness of the central region was 26.6 N / φ200. The 50% compressive hardness of the end regions was 57.7 N / φ200, and the 50% compressive hardness of the central region was 45.2 N / φ200. The hardness difference between the end regions and the central region at 25% and 50% compressive hardness was 3.0% and 27.8%, respectively. The results are shown in Tables 1 and 2.

[0080] [Example 6] Using a nozzle with an effective surface length of 890 mm in the width direction and 65 mm in the thickness direction, orifices with a hole diameter of 3.0 mm were arranged in a staggered pattern with a hole pitch of 6 mm, and the hole density was increased along the outer peripheral edge of the end region as shown in Figure 5. The obtained thermoplastic resin composition A-1 was discharged downward from the nozzle at a nozzle temperature (spinning temperature) of 240°C at a single-hole discharge rate of 1.35 g / min. After passing through a cooling space with an ambient temperature of 30°C, cooling water was placed 22 cm below the nozzle surface without blowing cooling air, and a pair of pull-up conveyors were placed parallel to a 150 cm wide stainless steel endless net with an opening width of 64 mm apart so that a portion of them was above the water surface. The molten continuous linear body was bent and twisted to form loops, fusing the contact parts together to form a three-dimensional random loop joint structure. The molten three-dimensional mesh structure described above was pulled into cooling water at a speed of 1.27 m / min while being sandwiched between two conveyors to solidify and flatten both sides. After that, it was cut to a predetermined size and dried with hot air at 110°C for 15 minutes to obtain a three-dimensional mesh structure. The properties of the three-dimensional mesh structure made of the obtained thermoplastic resin composition are shown in Tables 1 and 2.

[0081] The resulting three-dimensional network structure is mainly composed of hollow, round-section fibers with an average fiber diameter of 0.52 mm (a difference of 0.01 mm between the end and central regions), an average thickness of 61.1 mm, and an apparent density of 0.067 g / cm³ in the end regions. ３ The apparent density in the central region is 0.043 g / cm³. ３ The apparent density at the outer edge is 0.080 g / cm³. ３ The width of the end region that constitutes the seated position was 12 cm.

[0082] For the obtained three-dimensional mesh structure, the 25% compressive hardness of the end regions was 38.2 N / φ200, and the 25% compressive hardness of the central region was 37.4 N / φ200. The 50% compressive hardness of the end regions was 81.5 N / φ200, and the 50% compressive hardness of the central region was 66.9 N / φ200. The hardness difference between the end regions and the central region at 25% and 50% compressive hardness was 2.1% and 22.0%, respectively. The results are shown in Tables 1 and 2.

[0083] [Comparative Example 1] Using a nozzle with an effective surface length of 950 mm in the width direction and 45 mm in the thickness direction, orifices with a hole diameter of 5.0 mm were arranged in a staggered pattern with a hole pitch of 5 mm. The obtained thermoplastic resin composition A-1 was discharged downward from the nozzle at a nozzle temperature (spinning temperature) of 240°C at a single-hole discharge rate of 4.37 g / min. After passing through a cooling space with an ambient temperature of 30°C, cooling water was placed 25 cm below the nozzle surface without blowing cooling air, and a pair of pull-up conveyors were placed parallel to a 150 cm wide stainless steel endless net with an opening width of 45 mm apart, with a portion of each conveyor protruding above the water surface. The molten continuous linear material was bent and twisted to form loops, fusing the contact parts together to form a three-dimensional random loop joint structure. The molten three-dimensional mesh structure described above was pulled into cooling water at a speed of 2.90 m / min while being sandwiched between two conveyors to solidify and flatten both sides. After that, it was cut to a predetermined size and dried with hot air at 110°C for 15 minutes to obtain a three-dimensional mesh structure. The properties of the three-dimensional mesh structure made of the obtained thermoplastic resin composition are shown in Tables 1 and 2.

[0084] The resulting three-dimensional mesh structure is mainly composed of hollow cross-section fibers with a round cross-section and an average fiber diameter of 0.66 mm. It has an average thickness of 42.0 mm, and the apparent density is uniform in the end and central regions, with no high-density areas. This is the same configuration as conventional three-dimensional mesh structures, and the apparent density is 0.035 g / cm³. ３ The apparent density in the portion corresponding to the outer edge of the end region was 0.042 g / cm³. ３ That was the case.

[0085] The obtained three-dimensional mesh structure had a 25% compression hardness of 24.4 N / φ200 and a 50% compression hardness of 50.3 N / φ200. The results are shown in Tables 1 and 2.

[0086] The three-dimensional mesh structure of Comparative Example 1 lacked end regions with high apparent density, and therefore, it was deemed unsuitable because it may not be able to secure the 50% compression hardness necessary to support the user's body when localized loads such as those caused by sitting are applied.

[0087] [Comparative Example 2] Using a nozzle with an effective surface length of 890 mm in the width direction and 65 mm in the thickness direction, orifices with a hole diameter of 5.0 mm were arranged in a staggered pattern with a hole pitch of 5 mm, and the pore density in the end region was uniformly increased, and the obtained thermoplastic resin composition A-1 was discharged downward from the nozzle at a nozzle temperature (spinning temperature) of 240°C at a single-hole discharge rate of 3.22 g / min. After passing through a cooling space with an ambient temperature of 30°C, cooling water was placed 30 cm below the nozzle surface without blowing cooling air, and a pair of pull-up conveyors were placed parallel to a 150 cm wide stainless steel endless net with an opening width of 64 mm apart so that a portion of them was above the water surface. The molten continuous linear body was bent and twisted to form loops, fusing the contact parts together to form a three-dimensional random loop joint structure, creating a three-dimensional mesh structure. The molten three-dimensional mesh structure described above was pulled into cooling water at a speed of 1.55 m / min while being sandwiched between two conveyors to solidify and flatten both sides. After that, it was cut to a predetermined size and dried with hot air at 110°C for 15 minutes to obtain the three-dimensional mesh structure shown in Figure 3. The properties of the three-dimensional mesh structure made of the obtained thermoplastic resin composition are shown in Tables 1 and 2.

[0088] The resulting three-dimensional network structure is mainly composed of hollow, round-section fibers with an average fiber diameter of 0.83 mm (a difference of 0.02 mm between the end and central regions), an average thickness of 60.6 mm, and an apparent density of 0.068 g / cm³ in the end regions. ３ The apparent density in the central region is 0.042 g / cm³. ３ The apparent density at the outer edge is 0.073 g / cm³. ３ The width of the end region that constitutes the seated position was 12 cm.

[0089] For the obtained three-dimensional mesh structure, the 25% compressive hardness of the end regions was 105.0 N / φ200, and the 25% compressive hardness of the central region was 40.6 N / φ200. The 50% compressive hardness of the end regions was 180.6 N / φ200, and the 50% compressive hardness of the central region was 70.6 N / φ200. The hardness difference between the end regions and the central region at 25% and 50% compressive hardness was 158.8% and 155.8%, respectively. The results are shown in Tables 1 and 2.

[0090] The three-dimensional mesh structure of Comparative Example 2 exhibited an extreme difference in 25% and 50% compression hardness between the end regions and the central region. Therefore, when a user unconsciously moves from the central region to the end regions during sleep due to turning over, the difference in hardness may cause discomfort and disrupt sleeping comfort, making it unsuitable.

[0091] [Comparative Example 3] Using a nozzle with an effective surface length of 970 mm in the width direction and 45 mm in the thickness direction, 5.0 mm diameter orifices were arranged in a staggered pattern with a hole pitch of 5 mm, and the pore density was increased along the outer peripheral edge of the end region as shown in Figure 5. The obtained thermoplastic resin composition A-1 was discharged downward from the nozzle at a nozzle temperature (spinning temperature) of 240°C at a single-hole discharge rate of 3.93 g / min. After passing through a cooling space with an ambient temperature of 30°C, cooling water was placed 42 cm below the nozzle surface without blowing cooling air, and a pair of pull-up conveyors were placed parallel to a 150 cm wide stainless steel endless net with an opening width of 44 mm apart so that a portion of them was above the water surface. The molten continuous linear body was bent and twisted to form loops, fusing the contact parts together to form a three-dimensional random loop joint structure, creating a three-dimensional mesh structure. The molten three-dimensional mesh structure described above was pulled into cooling water at a speed of 2.21 m / min while being sandwiched between two conveyors to solidify and flatten both sides. After that, it was cut to a predetermined size and dried with hot air at 110°C for 15 minutes to obtain a three-dimensional mesh structure. The properties of the three-dimensional mesh structure made of the obtained thermoplastic resin composition are shown in Tables 1 and 2.

[0092] The resulting three-dimensional network structure is mainly composed of hollow, round-section fibers with an average fiber diameter of 0.66 mm (a difference of 0.01 mm between the end and central regions), an average thickness of 41.9 mm, and an apparent density of 0.052 g / cm³ at the end regions. ３ The apparent density in the central region is 0.043 g / cm³. ３ The apparent density at the outer edge is 0.081 g / cm³. ３ The width of the end region that constitutes the seated position was 15 cm.

[0093] For the obtained three-dimensional mesh structure, the 25% compressive hardness in the end regions was 50.1 N / φ200, and the 25% compressive hardness in the central region was 49.3 N / φ200. The 50% compressive hardness in the end regions was 85.8 N / φ200, and the 50% compressive hardness in the central region was 80.0 N / φ200. The hardness differences between the end regions and the central region at 25% and 50% compressive hardness were 1.6% and 7.3%, respectively. The results are shown in Tables 1 and 2.

[0094] The three-dimensional mesh structure of Comparative Example 3 had only a 20% difference in apparent density between the end regions and the central region, which meant it may not be able to secure the 50% compressive hardness necessary to support the user's body, and therefore was unsuitable.

[0095] [Comparative Example 4] On the effective surface of a nozzle with a length of 900 mm in the width direction and a length of 35 mm in the thickness direction, orifices with a hole diameter of 5.0 mm in the end region and a hole diameter of 3.0 mm in the central region were arranged in a staggered pattern with a hole pitch of 5 mm. The obtained thermoplastic resin composition A-1 was discharged downward from the nozzle at a nozzle temperature (spinning temperature) of 240°C at a single-hole discharge rate of 4.75 g / min. After passing through a cooling space with an ambient temperature of 30°C, cooling water was placed 42 cm below the nozzle surface without blowing cooling air, and a pair of pull-up conveyors were placed parallel to a 150 cm wide stainless steel endless net with an opening width of 34 mm apart so that a portion of them was above the water surface. The molten continuous linear material was bent and twisted to form loops, fusing the contact parts together to form a three-dimensional random loop joint structure. The molten three-dimensional mesh structure described above was pulled into cooling water at a speed of 2.85 m / min while being sandwiched between two conveyors to solidify and flatten both sides. After that, it was cut to a predetermined size and dried with hot air at 110°C for 15 minutes to obtain a three-dimensional mesh structure. The properties of the three-dimensional mesh structure made of the obtained thermoplastic resin composition are shown in Tables 1 and 2.

[0096] The resulting three-dimensional mesh structure is a three-dimensional mesh structure consisting of hollow cross-section fibers with a round cross-section, where the average fiber diameter in the end region is 0.86 mm and the average fiber diameter in the central region is 0.52 mm (a difference of 0.34 mm between the average fiber diameters of the end and central regions). It has an average thickness of 32.0 mm and an apparent density of 0.052 g / cm³ in the end region. ３The apparent density in the central region is 0.050 g / cm³. ３ The apparent density at the outer edge is 0.061 g / cm³. ３ The width of the end region that constitutes the seated position was 12 cm.

[0097] For the obtained three-dimensional mesh structure, the 25% compressive hardness of the end regions was 60.7 N / φ200, and the 25% compressive hardness of the central region was 41.1 N / φ200. The 50% compressive hardness of the end regions was 102.8 N / φ200, and the 50% compressive hardness of the central region was 71.9 N / φ200. The hardness difference between the end regions and the central region at 25% and 50% compressive hardness was 47.7% and 43.0%, respectively. The results are shown in Tables 1 and 2.

[0098] The three-dimensional mesh structure of Comparative Example 4 had an average fiber diameter difference of 0.34 mm between the end regions and the central region, resulting in an extreme difference in 25% compression hardness between the end regions and the central region. This could disrupt sleeping comfort due to discomfort caused by the difference in hardness when the user unconsciously moves to the end region during sleep, such as when turning over. Therefore, it was deemed unsuitable.

[0099]

[0100]

[0101] 1: Three-dimensional mesh structure 10: Central region 20: End regions 21: Inner layer 22: Surface layer 23: Outer edge L10: Length of the central region in the width direction L20: Length of the end regions in the width direction L21: Length of the inner layer in the width direction L22: Length of the surface layer in the width direction L23: Length of the outer edge in the width direction T21: Thickness of the inner layer T22: Thickness of the surface layer x: Width direction y: Length direction z: Thickness direction

Claims

1. A three-dimensional mesh structure comprising a continuous linear body made of a thermoplastic resin composition and having a three-dimensional random loop joint structure, wherein the three-dimensional mesh structure comprises a central region located in the center in the width direction of the three-dimensional mesh structure, and end regions located on both sides of the central region in the width direction, wherein the apparent density of the end regions is 30% or more higher than the apparent density of the central region, the end regions comprise an inner layer located inside in the thickness direction of the three-dimensional mesh structure, and surface layers located on both sides of the inner layer in the thickness direction, the difference between the apparent density of the inner layer and the apparent density of the central region is 20% or less, the difference between the 25% compressive hardness of the end regions and the 25% compressive hardness of the central region is 10% or less, and the 50% compressive hardness of the end regions is 15% or more higher than the 50% compressive hardness of the central region.

2. The three-dimensional mesh structure according to claim 1, wherein the end region has an outer edge on the end opposite to the side where the central region is located, and the apparent density of the outer edge is 30% or more higher than the apparent density of the central region.

3. The three-dimensional mesh structure according to claim 2, wherein the outer edge portion constitutes the end portion in the width direction of the three-dimensional mesh structure.

4. The three-dimensional mesh structure according to claim 2 or 3, wherein the length of the outer edge portion in the width direction of the three-dimensional mesh structure is shorter than the length of the inner layer portion and the length of the surface layer portion.

5. The three-dimensional mesh structure according to claim 1 or 2, wherein the thickness of the inner layer is greater than the thickness of the outer layer.

6. The three-dimensional mesh structure according to claim 1 or 2, wherein the length of the central region in the width direction of the three-dimensional mesh structure is longer than the length of the end regions in the width direction of the three-dimensional mesh structure.

7. The three-dimensional mesh structure according to claim 1 or 2, wherein the difference between the average fiber diameter of the continuous linear body having the central region and the average fiber diameter of the continuous linear body having the end region is 0.20 mm or less.

8. The three-dimensional mesh structure according to claim 1 or 2, wherein the number of joints per unit weight of the continuous linear body in the surface portion is greater than the number of joints per unit weight of the continuous linear body in the central region.

9. The three-dimensional network structure according to claim 1 or 2, wherein the thermoplastic resin composition constituting the continuous linear body comprises a polyester-based thermoplastic elastomer.

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