JP2017186687A - Net-like structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a net-like structure that has a soft touch feeling when used and less bottom-touch feeling, and is excellent in compression durability.SOLUTION: The net-like structure is a net-like structure having a three-dimensional random loop joint structure formed of a thermoplastic elastomer continuous linear body. In a thickness direction of the net-like structure, there exist a fine fiber main region comprising mainly fine fibers having a fiber diameter of 0.1 mm or more and 1.5 mm or less, a thick fiber main region comprising mainly thick fibers having a fiber diameter of 0.4 mm or more and 3.0 mm or less, and a mixture region between the fine fiber main region and the thick fiber main region in which fine fibers and thick fibers are mixed. The thick fiber has a fiber diameter thicker than the fine fiber by 0.07 mm or more. The residual strain after repeated compression with a 750 N constant load is 15% or less when pressure is applied from the fine fiber main region side of the net-like structure.SELECTED DRAWING: None

Description

  The present invention includes office chairs, furniture, sofas, beddings such as beds, seats for vehicles such as railways, automobiles, two-wheeled vehicles, strollers, child seats, wheelchairs, floor mats, mats for impact absorption such as collision and pinching prevention members, etc. The present invention relates to a net-like structure suitable for a net-like cushion material used in the above.

  Currently, mesh structures are being widely used as cushion materials used for furniture, bedding such as beds, and seats for vehicles such as trains, automobiles, and motorcycles.

  Patent Document 1 describes a network structure in which the continuous linear body constituting the network structure is composed only of solid cross-section fibers (referred to as fibers having a solid cross section; the same shall apply hereinafter). Solid cross-section fibers are heavier in the case of the same material and the same fiber diameter compared to hollow cross-section fibers (referring to fibers having a hollow cross section; the same shall apply hereinafter). In order to reduce the weight of the net-like structure, the net-like structure in which the continuous linear body is composed only of solid cross-section fibers usually has a smaller diameter of the continuous linear body than the network structure composed of only hollow cross-section fibers. Alternatively, the increase in weight is often suppressed by reducing the number of constituent fibers of the network structure, and as a result, the resulting network structure often has a feeling of bottoming.

  Patent Document 2 describes a network structure in which a continuous linear body constituting the network structure is composed of only hollow cross-section fibers. A network structure composed only of hollow cross-section fibers can be reduced in weight as compared to a network structure composed only of solid cross-section fibers, and has the advantage that the hardness of the network structure can be increased with the same weight. However, since the fiber diameter is thicker than that of the solid cross-section fiber, there is a problem that it is difficult to obtain a soft touch when used as a cushioning material or the like.

  Patent Document 3 describes a network structure composed of continuous linear bodies having different fiber diameters. The network structure is composed of a basic layer responsible for vibration absorption and body shape maintenance composed of continuous filaments with a large fiber diameter, and a surface layer responsible for soft and uniform pressure dispersion composed of continuous filaments with a narrow fiber diameter. ing. Patent Document 3 also describes a network structure in which a basic layer made of a continuous linear body having a large fiber diameter and a surface layer made of a continuous linear body having a thin fiber diameter are not melt bonded. However, the network structure described in Patent Document 3 and a network structure in which a plurality of network structures are laminated without being melt-bonded have a compression durability that assumes a sag in actual use of the network structure. The residual strain after repeated compression at a constant load of 750 N, which is an index of the above, was a problem.

JP 7-68061 A Japanese Patent Laid-Open No. 7-173753 JP 7-189105 A

  The present invention has been made against the background of the above-described problems of the prior art, and it is an object of the present invention to provide a network structure that has a soft tactile sensation during use, has a low bottoming feeling, and is excellent in compression durability. To do.

  As a result of intensive studies to solve the above problems, the present inventors have finally completed the present invention. That is, the present invention is as follows.

  [1] A network structure having a three-dimensional random loop joining structure made of a continuous linear body of thermoplastic elastomer, the fiber diameter being mainly 0.1 mm or more and 1.5 mm or less in the thickness direction of the network structure A fine fiber main region composed of thin fibers, a thick fiber main region mainly composed of thick fibers having a fiber diameter of 0.4 mm to 3.0 mm, and a thin fiber positioned between the fine fiber main region and the thick fiber main region There is a mixed region in which fibers and thick fibers are mixed, and the fiber diameter of the thick fibers is 0.07 mm or more thick compared to the thin fibers, and when pressed from the fine fiber main region side of the network structure A network structure having a residual strain of 15% or less after 750 N constant load repeated compression.

[2] network structure according to the apparent density of 0.005 g / cm ³ or more 0.20 g / cm ³ or less is the [1].

  [3] The network structure according to [1] or [2], wherein the thin fibers are solid cross-section fibers having a solid cross section, and the thick fibers are hollow cross-section fibers having a hollow cross section.

  [4] The network structure according to any one of [1] to [3], wherein a hysteresis loss when pressed from the fine fiber main region side of the network structure is 60% or less.

  [5] A cushioning material including the network structure according to any one of [1] to [4] above in the cushion.

  According to the present invention, it is possible to provide a network structure that has a soft tactile sensation during use, has a feeling of bottoming, and is excellent in compression durability. Therefore, it has become possible to provide a net-like structure suitably used for office chairs, furniture, bedding such as sofas and beds, and seats for vehicles such as railways, automobiles, and motorcycles.

It is a typical graph of the compression / decompression test in the hysteresis loss measurement of a network structure.

  Hereinafter, embodiments of the present invention will be described in detail. The network structure of the present invention is a network structure having a three-dimensional random loop joining structure composed of a thermoplastic elastomer continuous linear body, and the fiber diameter is mainly 0.1 mm or more in the thickness direction of the network structure. A fine fiber main region composed of fine fibers of 1.5 mm or less, a thick fiber main region mainly composed of thick fibers having a fiber diameter of 0.4 mm to 3.0 mm, and a fine fiber main region and a thick fiber main region. There is a mixed region formed by mixing thin fibers and thick fibers located between them, and the fiber diameter of the thick fibers is 0.07 mm or more thick compared to the thin fibers, and from the fine fiber main region side of the network structure The residual strain after repeated compression at a constant load of 750 N when pressurized is 15% or less. The network structure of the present invention has a soft tactile sensation during use since the fiber diameter of the thin fibers is 0.1 mm or more and 1.5 mm or less, and the fiber diameter of the thick fibers is 0.07 mm or more than the fiber diameter of the thin fibers. Because it is thick, there is little feeling of bottoming, there is a mixed region between the fine fiber main region and the thick fiber main region, and the residual strain after repeated compression at 750 N constant load when pressed from the fine fiber main region side is 15% It is excellent in compression durability from the following.

  The network structure of the present invention has a three-dimensional random loop joining structure in which a continuous linear body made of a thermoplastic elastomer is twisted to form a random loop, and each loop is brought into contact with each other in a molten state and joined. It is a structure.

  Examples of the thermoplastic elastomer of the present invention include polyester-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, thermoplastic ethylene-vinyl acetate copolymer elastomers, and the like. Of these, polyester-based thermoplastic elastomers are preferable because they are excellent in compression durability and heat resistance.

  As the polyester-based thermoplastic elastomer in the present invention, a polyester ether block copolymer having a thermoplastic polyester as a hard segment and a polyalkylene diol as a soft segment, or a polyester ester block copolymer having an aliphatic polyester as a soft segment. Can be illustrated.

  As a polyester ether block copolymer, the ternary block copolymer comprised from the dicarboxylic acid, the diol component, and the polyalkylenediol can be illustrated. Dicarboxylic acids include terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4′-dicarboxylic acid and other aromatic dicarboxylic acids, 1,4-cyclohexane Examples include at least one dicarboxylic acid selected from alicyclic dicarboxylic acids such as dicarboxylic acids, aliphatic dicarboxylic acids such as oxalic acid, adipic acid, sebacic acid, and dimer acid, or ester-forming derivatives thereof. . Examples of the diol component include aliphatic diols such as 1,4-butanediol, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, 1,1-cyclohexanedimethanol, 1,4-cyclohexanedi Examples thereof include at least one diol component selected from alicyclic diols such as methanol or ester-forming derivatives thereof. Examples of the polyalkylene diol include at least one of polyalkylene diols such as polyethylene glycol having a number average molecular weight of about 300 to 5,000, polypropylene glycol, polytetramethylene glycol, and glycol made of an ethylene oxide-propylene oxide copolymer.

  As a polyester ester block copolymer, the ternary block copolymer comprised from the dicarboxylic acid, the diol component, and the polyester diol can be illustrated. Examples of the dicarboxylic acid and diol component include the above-mentioned dicarboxylic acid and diol component. Examples of the polyester diol include at least one kind of polyester diol such as polylactone having a number average molecular weight of about 300 to 5,000.

  In consideration of thermal adhesiveness, hydrolysis resistance, stretchability, heat resistance, etc., in the polyester ether block copolymer, the dicarboxylic acid is terephthalic acid and / or naphthalene 2,6-dicarboxylic acid, and the diol component is 1,4- Butanediol and polyalkylenediol are particularly preferably ternary block copolymers composed of polytetramethylene glycol. In the polyester ester copolymer, 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 a ternary block copolymer composed of polylactone. Is particularly preferred. As a special example, a polysiloxane-based soft segment can be used.

  The soft segment content of the polyester-based thermoplastic elastomer of the present invention is preferably 15% by weight or more, more preferably 25% by weight or more, and further preferably 30% by weight or more, from the viewpoint of excellent compression durability. The amount is particularly preferably 40% by weight or more, and preferably 80% by weight or less, more preferably 70% by weight or less, from the viewpoint of ensuring hardness and excellent heat resistance and sag resistance.

  The polyolefin-based thermoplastic elastomer in the present invention is preferably an ethylene / α-olefin copolymer obtained by copolymerizing ethylene and an α-olefin, from ethylene and α-olefin as an olefin block copolymer. It is more preferable that it is a multiblock copolymer. It is more preferable that the multi-block copolymer is composed of ethylene and α-olefin. In the case of a general random copolymer, the connecting chain length of the main chain is shortened, the crystal structure is hardly formed, and the durability is lowered. It is to do. From this viewpoint, the α-olefin copolymerized with ethylene is preferably an α-olefin having 3 or more carbon atoms.

  Here, examples of the α-olefin having 3 or more carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene and the like are preferable, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1- Tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene and 1-eicosene. Two or more of these can also be used.

  The random copolymer that is the ethylene / α-olefin copolymer of the present invention is a copolymer of ethylene and an α-olefin using a catalyst system having a basic structure of a specific metallocene compound and an organometallic compound. The multiblock copolymer can be obtained by copolymerizing ethylene and α-olefin using a chain shuttling reaction catalyst. If necessary, two or more kinds of polymers polymerized by the above method, or polymers such as hydrogenated polybutadiene and hydrogenated polyisoprene can be blended.

  The ratio of ethylene to α-olefin having 3 or more carbon atoms in the ethylene / α-olefin copolymer in the present invention is such that ethylene is 70 mol% or more and 95 mol% or less, and α-olefin having 3 or more carbon atoms is 5 mol% or more. 30 mol% or less is preferable. In general, it is known that a polymer compound is elastomeric because a hard segment and a soft segment are present in a polymer chain. In the polyolefin-based thermoplastic elastomer of the present invention, it is considered that ethylene plays a role of a hard segment, and α-olefin having 3 or more carbon atoms plays a role of a soft segment. Therefore, when the ratio of ethylene is less than 70 mol%, since there are few hard segments, the recovery performance of rubber elasticity is lowered. The ratio of ethylene is more preferably 75% or more, and still more preferably 80 mol% or more. On the other hand, when the ratio of ethylene exceeds 95 mol%, since there are few soft segments, elastomeric properties are hardly exhibited and cushion performance is inferior. The ratio of ethylene is more preferably 93 mol% or less, still more preferably 90 mol% or less.

  The polyurethane-based thermoplastic elastomer in the present invention includes a polyester and / or polyester having a hydroxyl group at the terminal having a number average molecular weight of 1000 to 6000 in the presence or absence of a normal solvent (dimethylformamide, dimethylacetamide, etc.) A typical example is a polyurethane elastomer obtained by reacting a polyisocyanate containing an organic diisocyanate as a main component with a polypolymer having a diamine as a main component on a prepolymer having both ends being isocyanate groups. . Examples of the polyester and / or polyether include polybutylene adipate copolymer polyester having a number average molecular weight of about 1000 to 6000, preferably 1300 to 5000, polyethylene glycol, polypropylene glycol, polytetramethylene glycol. And polyalkylenediols such as glycols made of ethylene oxide-propylene oxide copolymer are preferred. As the polyisocyanate, a conventionally known polyisocyanate can be used. An isocyanate mainly composed of diphenylmethane 4,4′-diisocyanate is used, and a small amount of a conventionally known triisocyanate is added if necessary. May be used. As the polyamine, a known diamine such as ethylenediamine or 1,2-propylenediamine is mainly used, and a trace amount of triamine or tetraamine may be used in combination as required. These polyurethane-based thermoplastic elastomers may be used alone or in combination of two or more.

  The soft segment content of the polyurethane-based thermoplastic elastomer in the present invention is preferably 15% by weight or more, more preferably 25% by weight or more, and further preferably 30% by weight or more, from the viewpoint of excellent compression durability. The amount is most preferably 40% by weight or more, and preferably 80% by weight or less, more preferably 70% by weight or less, from the viewpoint of securing hardness and excellent heat resistance and sag resistance.

  Examples of the polyamide-based elastomer in the present invention include those in which polyamide is used as a hard segment, polyol is used as a soft segment, and both are copolymerized. The polyamide which is a hard segment includes at least one kind of polyamide oligomers obtained from a reaction product such as a lactam compound and a dicarboxylic acid or a diamine and a dicarboxylic acid. The polyol which is a soft segment includes at least one of polyether polyol, polyester polyol, polycarbonate polyol and the like.

  Examples of the lactam compound include at least one of aliphatic lactams having 5 to 20 carbon atoms such as γ-butyrolactam, ε-caprolactam, ω-heptalactam, ω-undecalactam, and ω-lauryllactam.

  Dicarboxylic acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid and other aliphatic dicarboxylic acids having 2 to 20 carbon atoms, and cyclohexanedicarboxylic acid and other fats Examples include at least one dicarboxylic acid compound such as an aromatic dicarboxylic acid such as a cyclic dicarboxylic acid, terephthalic acid, isophthalic acid, or orthophthalic acid.

As diamines, ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecanemethylenediamine, 2,2,4-trimethylhexa Examples include at least one of aliphatic diamines such as methylenediamine, 2,4,4-trimethylhexamethylenediamine, and 3-methylpentamethylenediamine, and aromatic diamines such as metaxylenediamine.
As for the polyol, a polyether polyol such as polyethylene glycol having a number average molecular weight of about 300 to 5,000, polypropylene glycol, polytetramethylene glycol, glycol comprising an ethylene oxide-propylene oxide copolymer, etc. Among the alkylene diols, at least one kind may be mentioned. The polycarbonate diol is a reaction product of a low molecular diol and a carbonate compound, and has a number average molecular weight of about 300 to 5,000. Low molecular diols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6 -Aliphatic diols such as hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and cycloaliphatic diols such as cyclohexanedimethanol and cyclohexanediol. Among these, at least one or more are listed. Examples of the carbonate compound include at least one of dialkyl carbonate, alkylene carbonate, diaryl carbonate and the like. Moreover, as a polyester polyol, at least 1 sort (s) or more is mentioned among polyester diols, such as polylactone with a number average molecular weight of about 300-5000.

  The soft segment content of the polyamide-based thermoplastic elastomer of the present invention is preferably 5% by weight or more, more preferably 10% by weight or more, and further preferably 15% by weight or more, from the viewpoint of excellent compression durability. The amount is most preferably 20% by weight or more, and preferably 80% by weight or less, more preferably 70% by weight or less, from the viewpoint of ensuring hardness and excellent heat resistance and sag resistance.

  As the thermoplastic ethylene vinyl acetate copolymer elastomer of the present invention, the polymer constituting the network structure preferably has a vinyl acetate content of 1 to 35%. The vinyl acetate content is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more from the viewpoint that the rubber elasticity may be poor when the vinyl acetate content is small. When the vinyl acetate content is increased, the rubber elasticity is excellent, but from the viewpoint that the melting point is lowered and the heat resistance may be poor, the vinyl acetate content is preferably 35% or less, more preferably 30% or less, and 26% or less. Is more preferable.

  The thermoplastic ethylene-vinyl acetate copolymer elastomer can also be copolymerized with an α-olefin having 3 or more carbon atoms. Here, examples of the α-olefin having 3 or more carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene and the like are preferable, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1- Tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene and 1-eicosene. Two or more of these can also be used.

  The continuous linear body constituting the network structure of the present invention can be composed of a mixture of two or more different thermoplastic elastomers depending on the purpose. When composed of a mixture of two or more different thermoplastic elastomers, at least one selected from the group consisting of polyester-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers The thermoplastic elastomer is preferably contained in an amount of 50% by weight or more, more preferably 60% by weight or more, and further preferably 70% by weight or more.

  Various additives can be blended in the continuous linear thermoplastic elastomer constituting the network structure of the present invention according to the purpose. Additives include plasticizers such as phthalate ester, trimellitic ester, fatty acid, epoxy, adipic ester, polyester, etc., known hindered phenols, sulfur, phosphorus, amines, etc. Antioxidants, hindered amines, triazoles, benzophenones, benzoates, nickels, salicyls and other light stabilizers, antistatic agents, molecular weight modifiers such as peroxides, epoxy compounds, isocyanate compounds, carbodiimides Compounds having reactive groups such as organic compounds, metal deactivators, organic and inorganic nucleating agents, neutralizing agents, antacids, antibacterial agents, fluorescent brighteners, fillers, flame retardants, flame retardant aids Organic and inorganic pigments can be added.

  The continuous linear body constituting the network structure of the present invention has an endothermic peak below the melting point of the thermoplastic elastomer constituting the continuous linear body in the melting curve measured with a differential scanning calorimeter (DSC). Is preferred. A network structure composed of a continuous linear body having an endothermic peak below the melting point has a significantly improved heat sag resistance than that without an endothermic peak. In order to further improve the heat resistance and sag resistance of the network structure, the continuous linear body is subjected to an annealing treatment at a temperature lower by at least 10 ° C. than the melting point of the thermoplastic elastomer constituting the continuous linear body after melting and heat bonding. It is also preferable. When annealing is performed after applying a compressive strain to the network structure, the heat resistance and sag resistance are further improved. The continuous linear body of the network structure subjected to such treatment expresses an endothermic peak more clearly at a temperature of 20 ° C. or higher and a melting point or lower on a melting curve measured by a differential scanning calorimeter (DSC). When annealing is not performed, the endothermic peak does not appear in the melting curve at 20 ° C. or higher and the melting point or lower. By analogy with this, it is considered that the hard segments are rearranged by annealing and pseudo-crystallization-like cross-linking points are formed, and the heat resistance and sag resistance are improved. Hereinafter, this annealing process may be referred to as “pseudo crystallization process”. This pseudo-crystallization treatment effect is also effective for polyolefin-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and polyurethane-based thermoplastic elastomers.

  The network structure of the present invention is a network structure having the three effects of having a soft tactile sensation during use, less bottoming feeling, and excellent compression durability. A method of obtaining a network structure having the above three effects is mainly a fine fiber main region composed mainly of fine fibers having a fiber diameter of 0.1 mm or more and 1.5 mm or less, at least in the thickness direction of the network structure. A mixed region in which a thick fiber main region composed of thick fibers having a fiber diameter of 0.4 mm or more and 3.0 mm or less, and a thin fiber and a thick fiber located between the thin fiber main region and the thick fiber main region are mixed. There is a residual strain after repeated compression at a constant load of 750 N when the fiber diameter of the thick fiber is 0.07 mm or more thick compared to the thin fiber and the network is pressed from the fine fiber main region side. It must be 15% or less.

  “Mainly” in the fine fiber main region means that the ratio of the number of fine fibers to the total number of fibers contained in the region is 90% or more. “Mainly” in the thick fiber main region means that the ratio of the number of fibers having a large fiber diameter to the total number of fibers contained in the region is 90% or more. Moreover, in the mixed region formed by mixing fine fibers and thick fibers located between the fine fiber main region and the thick fiber main region, the ratio of the number of fine fibers to the total number of fibers contained in the region Is lower than the fine fiber main region, and the ratio of the number of thick fibers to the total number of fibers contained in the region is lower than that of the thick fiber main region. That is, the mixed region means a region where both the number of fine fibers and the number of thick fibers are less than 90% of the total number of fibers contained in the region.

  Here, the ratio of the number of fibers of each fiber in the predetermined region is measured by the following method. First, 10 samples are cut out in a size of 3 cm in the width direction × 3 cm in the length direction × sample thickness, and the weight of each sample is measured with an electronic balance. Next, the fibers constituting the sample are extracted one by one from the same surface side of each sample so as to reduce the sample thickness as uniformly as possible. The process of drawing out the fibers one by one is continued until the sample weight reaches 90% of the weight of the sample prepared first. The diameter of the extracted fiber is confirmed visually or with an optical microscope, and divided into thin fibers and thick fibers, and the number of thin fibers and thick fibers is counted. As will be described later, when the thin fiber is a solid cross-section fiber having a solid cross section and the thick fiber is a hollow cross-section fiber having a hollow cross section, the cross section of the extracted fiber is confirmed visually or by an optical microscope. By doing so, it can be divided into thin fibers and thick fibers. Add the number of thin fibers and thick fibers of 10 samples to obtain the total number of fibers contained in the region. From the number of fine fibers and the number of thick fibers to the total number of fibers contained in the area, the ratio of the number of fine fibers and the number of thick fibers is calculated. It is determined whether it is a fiber main region or a mixed region.

  Subsequently, the operation of extracting fibers from each sample was resumed, and the operation of extracting fibers one by one was continued until the sample weight became the first 80% or less of the weight of the sample prepared first. In the same manner as above, the ratio of the number of thin fibers and the number of thick fibers is calculated from the number of thin fibers and the number of thick fibers from the total number of fibers contained in the region. It is determined whether it is a fiber main region, a thick fiber main region, or a mixed region.

  After that, until the sample weight first begins to be less than 70% of the weight of the initially prepared sample, until the sample weight begins to be less than 60% of the weight of the first prepared sample, Sample weight until sample weight is first less than 40% of first sample weight until sample weight is first less than 50% of first sample weight Until the first sample weight is less than 20% of the weight of the first sample, until the first sample weight is less than 30% of the first sample weight. Fibers from each sample approximately every 10% of the sample weight until the first weight of the sample prepared is less than 10%, and until the sample weighs 0%. Repeat the extraction process. In the same manner as described above, the number of thin fibers and the number of thick fibers are calculated from the number of thin fibers and the number of thick fibers with respect to the total number of fibers included in each region divided into 10 in the thickness direction from the surface side. The ratio of the number of fibers is calculated, and it is determined whether each region is a fine fiber main region, a thick fiber main region, or a mixed region.

  The network structure of the present invention has a residual strain after 750 N constant load repeated compression (hereinafter also referred to as 750 N constant load repeated compression from the fine fiber main region side) when pressurized from the fine fiber main region side of the network structure. However, it is 15% or less, Preferably it is 13% or less, More preferably, it is 11% or less, More preferably, it is 10% or less. In a multi-layered network structure having a structure in which a continuous linear body is formed by laminating a layer mainly composed of thin fibers and a layer composed of continuous fibers mainly composed of thick fibers, a layer composed mainly of thin fibers (i.e. The residual strain after the 750N constant load repeated compression from the fine fiber main region) side is more than the residual strain after the 750N constant load repeated compression mainly from the thick fiber layer (ie, the thick fiber main region) side. large. Therefore, a low value of residual strain after 750 N constant load repeated compression from the fine fiber main region side means that the compression durability of the entire network structure is good.

  In order to reduce the residual strain after the 750N constant load repeated compression from the fine fiber main region side, a thin fiber and a thick fiber are mixed at a position between the fine fiber main region and the thick fiber main region. It is important that the thickness of the entire network structure is formed by the existence of mixed regions and the integration of these regions without separation.

  There is no mixed region consisting of thin fibers and thick fibers, and the network structure consisting mainly of thin fibers and the network structure consisting mainly of thick fibers can be easily separated. Even with a two-layer laminated network structure that is not integrated, it is possible to obtain a network structure that has a soft tactile sensation during use and a low feeling of bottoming. However, in the above layered laminated network structure, when the continuous linear body is compressed and compressed from the surface of the network structure having a low compression hardness composed of thin fibers, first, the continuous linear body is composed of thin fibers. Only the low-net-like network structure is compressively deformed, and the continuous linear body is composed of thin fibers, and only the low-compressed-hardness network structure is independent of the high-compressed network structure composed of thick fibers. Deflection. At the stage where the continuous linear body is made up of thin fibers composed of thin fibers and has a low compressive hardness and cannot withstand the compressive load, the continuous linear body is finally composed of thick fibers and the compressive stress is applied to the high compressive network structures. Propagation begins and deformation and deflection of the network structure with high compressive hardness, the continuous linear body consisting of thick fibers. For this reason, when pressure compression is repeated, the network structure with low compression hardness, in which the continuous linear body is composed of thin fibers, accumulates fatigue earlier, and the network structure with high compression hardness, in which the continuous linear body is composed of thick fibers. Thickness reduction and compression hardness reduction progress than the body. That is, the network structure as a whole has a network structure with low compression durability.

  Further, there is no mixed region in which thin fibers and thick fibers are mixed, but a network structure mainly composed of thin fibers and a network structure mainly composed of thick fibers are bonded and integrated by bonding 2 Even with a sheet-laminated laminated network structure, it is possible to obtain a network structure with a soft tactile sensation during use and a low feeling of bottoming. However, in the above-mentioned laminated laminated network structure, the initial stage of repeated compression is such that both network structures are deformed as a unit against the pressure compression load, but stress is applied to the adhesive surface as compression is repeated. As a result, the adhesive strength is reduced and peeling occurs, so that the two-layer laminated network structure is a network structure having a low compression durability as a whole.

  In addition, there is no mixed area where thin fibers and thick fibers are mixed, but a fine fiber main area mainly composed of thin fibers and a thick fiber main area mainly composed of thick fibers are fused and integrated. Even in the case of a structure, it is possible to obtain a network structure that has a soft tactile sensation during use and a low feeling of bottoming. Such a network structure can be obtained by a method in which thin fibers are discharged onto a network structure mainly composed of thick fibers, and a network structure mainly composed of thin fibers is fused and laminated. However, since the network structure obtained by this method fuses thin fibers once thick fibers are solidified, the fusion force at the interface between the thick fiber layer and the thin fiber layer is low, and repeated compression load is applied. When it receives, stress concentrates on the boundary surface and interface peeling occurs, resulting in poor compression durability.

  The network structure of the present invention has a mixed region in which a thin fiber and a thick fiber are mixed between a fine fiber main region and a thick fiber main region, and these regions are integrated without being separated. In the case of a network structure in which the thickness of the entire network structure is formed, even if the continuous linear body is compressed and compressed from the side of the fine fiber main region having a low compression hardness consisting mainly of fine fibers, From the initial stage of compression, the stress propagates to the thick fiber main region side where the continuous linear body is mainly composed of thick fibers and has high compression hardness, and the stress is efficiently dispersed in the thickness direction. The entire network structure is deformed. As a result, the residual strain after repeated compression at a constant load of 750 N when the continuous linear body is mainly pressed from the side of the fine fiber main region having a low compression hardness consisting of fine fibers is reduced, and the compression durability of the entire network structure is reduced. The property is also increased.

  The network structure of the present invention can be obtained by adding a new technique to a known method described in Japanese Patent Application Laid-Open No. 2014-194099. For example, a thermoplastic elastomer is distributed to the nozzle orifice from a plurality of orifices having a plurality of orifices and a plurality of different orifice hole diameters, which will be described later, and the spinning temperature is higher than the melting point of the thermoplastic elastomer by 20 ° C. or more and less than 120 ° C. It is discharged downward and brought into contact with each other in a molten state to form a three-dimensional structure, sandwiched by a take-up conveyor net, cooled with cooling water in a cooling tank, and then drawn out and drained. After or drying, a network structure having smoothed both sides or one side is obtained. In the case of smoothing only one surface, it is preferable that cooling is performed while relaxing the shape of only the take-up net surface while discharging it onto an inclined take-up net and bringing it into contact with each other in a molten state to form a three-dimensional structure. The obtained network structure can be annealed. The drying process of the network structure may be an annealing process.

  As a means for obtaining the network structure of the present invention, it is preferable to optimize the nozzle shape, dimensions, and nozzle hole arrangement. With respect to the nozzle shape, the orifice diameter for forming fine fibers is preferably 1.5 mm or less, and the orifice diameter for forming thick fibers is preferably 2 mm or more. Moreover, it is preferable that the nozzle orifice shape which forms a thick fiber has a hollow formability, and a C type nozzle, a 3-point bridge shape nozzle, etc. are mentioned, However, From a pressure | voltage resistant viewpoint, it is preferable that it is a 3-point bridge shape nozzle. The inter-hole pitch is preferably 4 mm or more and 12 mm or less, and more preferably 5 mm or more and 11 mm or less for both the orifice forming the fine fibers and the orifice forming the thick fibers. Examples of the nozzle hole array include a lattice array, a circumferential array, a staggered array, and the like, but a lattice array or a staggered array is preferable from the viewpoint of the quality of the network structure. Here, the inter-hole pitch is the distance between the centers of the nozzle holes, the inter-hole pitch in the width direction of the network structure (hereinafter also referred to as “width-direction hole pitch”), and the thickness direction of the network structure. Between the holes (hereinafter also referred to as “thickness direction hole pitch”). About the suitable hole pitch as described above, the hole pitch suitable for both the width direction hole pitch and the thickness direction hole pitch is described.

As a nozzle for obtaining the network structure of the present invention,
Group a: Orifice hole group configured by arranging a plurality of fine fiber orifice holes in the thickness direction,
ab mixed group: an orifice hole group constituted by arranging a plurality of thin fiber orifice holes and thick fiber orifice holes in a plurality of rows in the thickness direction;
b group: Orifice hole group composed of a plurality of thick fiber orifice holes arranged in the thickness direction,
No. 3 nozzles (a group, ab mixed group, and b group).

As another nozzle,
α group: Orifice hole group composed of multiple orifice holes for thin fibers arranged in the thickness direction,
β group: Orifice hole group composed of a plurality of thick orifice holes for fibers arranged in the thickness direction,
And a nozzle having a small difference between the widthwise hole pitch of the fine fiber orifice and the widthwise hole pitch of the thick fiber orifice. From the viewpoint of simplifying the nozzle structure, the nozzles composed of the α group and the β group are more preferable.

  Although the number of orifice holes in the nozzle is two, the fibers spun from the vicinity of the boundary surface between the α group and the β group form a mixed region in which thin fibers and thick fibers are mixed. A network structure including three regions in the vertical direction can be obtained.

  In order to obtain a network structure excellent in compression durability according to the present invention, it is necessary to reduce the difference between the widthwise hole pitch of the fine fiber orifice and the widthwise hole pitch of the thick fiber orifice. Although the whole reason why the difference in durability is reduced when the difference in pitch between the widthwise holes is small is not clarified, it is estimated as follows.

  In a mixed region where thin fibers and thick fibers are mixed, a small difference in pitch between holes in the width direction of the orifice means that the number of thin fibers and thick fibers in the mixed region is close. When the number of thin fibers and thick fibers is close, it can be said that the thin fibers and the thick fibers constitute a plurality of contact points in a one-to-one manner. Therefore, even when the continuous linear body is pressurized from the side mainly composed of fine fibers (the fine fiber main region side), it is considered that the compression durability is improved because stress easily propagates.

  On the other hand, when a network structure is formed with a nozzle having a large difference in the pitch between holes in the width direction of the orifice, in the mixed region where thin fibers and thick fibers are mixed, for example, the structure of fibers with a large number of thin fibers When the number is larger than the number, in the mixed region, some of the thin fibers have thick fibers and few contacts. For this reason, when the continuous linear body is pressurized from the side consisting mainly of thick fibers (thick fiber main region side), there are fine fibers from which the stress hardly propagates from the thick fibers, and the stress propagates from the thick fibers. It is thought that stress is propagated through the formed thin fibers. On the other hand, when the continuous linear body is pressurized from the side mainly composed of fine fibers (fine fiber main region side), there are fine fibers that cannot propagate stress to thick fibers, and they can propagate stress to thick fibers. It is thought that stress is propagated to thick fibers via thin fibers.

  That is, when a network structure is formed with a nozzle having a large difference in pitch between holes in the width direction of the orifice, the direction of stress propagation is the thickness direction in the mixed region where thin fibers and thick fibers are mixed. Since it disperses in the direction perpendicular to the thickness direction, the propagation efficiency of the stress decreases, so the continuous linear body is continuous with the case where it is mainly pressed from the side consisting of fine fibers (fine fiber main region side). There is a large difference in compression durability when the linear body is mainly pressed from the side consisting of thick fibers (thick fiber main region side), and the compression durability when pressed from the fine fiber main region side It is thought that it becomes a network structure inferior to.

  The difference between the widthwise hole pitch of the fine fiber orifice and the widthwise hole pitch of the thick fiber orifice is preferably 2 mm or less, more preferably 1 mm or less, and 0 mm, that is, between the width direction holes. More preferably, the pitch is the same.

  The fiber diameter of the fine fibers mainly constituting the fine fiber main region of the network structure of the present invention is 0.1 mm or more and 1.5 mm or less, preferably 0.2 mm or more and 1.4 mm or less, and 0.3 mm or more and 1. 3 mm or less is more preferable. If the fiber diameter is less than 0.1 mm, it will be too thin and the fineness and soft feel will be good, but it will be difficult to secure the necessary hardness as a network structure, and if the fiber diameter exceeds 1.5 mm, it will be soft. It may be difficult to obtain a good tactile sensation.

  The fiber diameter of the thick fibers mainly constituting the thick fiber main region of the network structure of the present invention is 0.4 mm or more and 3.0 mm or less, preferably 0.5 mm or more and 2.5 mm or less, and 0.6 mm or more and 2. 0 mm or less is more preferable. If the fiber diameter is less than 0.4 mm, it will be too thin and it will be difficult to ensure the required hardness as a network structure. If the fiber diameter exceeds 3.0 mm, the hardness of the network structure can be ensured. May become rough and compression durability may be inferior.

  The fiber diameter of the thin fibers and the thick fibers of the continuous linear body constituting the network structure of the present invention is 0.07 mm or more thick, preferably 0.10 mm or more thick, and preferably 0.12 mm or more thick. Is more preferably 0.15 mm or thicker, particularly preferably 0.20 mm or thicker, and most preferably 0.25 mm or thicker. In the present invention, the upper limit of the difference in fiber diameter between the thick fiber and the thin fiber is preferably 2.5 mm or less. If the thick fiber is less than 0.07 mm thicker than the fiber diameter of the thin fiber, the network structure may have a bottoming feeling. Conversely, if the difference in fiber diameter is too large, the feeling of foreign matter will be excessive, so it is necessary to set it within an appropriate range.

  The total weight ratio of the thin fibers constituting the network structure of the present invention is preferably 10% or more and 90% or less with respect to the total fibers constituting the network structure. In order to impart a soft tactile sensation to the network structure of the present invention, it is preferably 20% or more and 80% or less, and more preferably 30% or more and 70% or less. If it is less than 10% or more than 90%, it may not be possible to give a soft tactile feel to the network structure.

  In the network structure of the present invention, it is preferable that the thin fibers are solid cross-section fibers having a solid cross section, and the thick fibers are hollow cross-section fibers having a hollow cross section. This is because a thin fiber can be produced if it is a solid cross-section fiber, and a thin fiber can be manufactured if the fiber is a hollow cross-section fiber. Solid cross-section fibers and hollow cross-section fibers are identified by visual observation or observation with an optical microscope or the like.

  The continuous linear body constituting the network structure of the present invention may be a composite linear combination with another thermoplastic resin as long as the object of the present invention is not impaired. Examples of the composite form include composite linear bodies such as a sheath / core type, a side-by-side type, and an eccentric sheath / core type when the linear body itself is combined.

  The cross-sectional shape of the continuous linear body constituting the network structure of the present invention is preferably substantially circular, but there may be a case where an anti-compression property or a touch can be imparted by using an atypical cross section.

  In the continuous linear body constituting the network structure of the present invention, a drug having functions such as deodorizing antibacterial, deodorizing, antifungal, coloring, aroma, flame retardant, moisture absorption and desorption etc. is added within a range not deteriorating the performance. Further, it can be contained in the thermoplastic elastomer constituting the continuous linear body and / or adhered to the surface of the continuous linear body by a treatment such as addition.

  The network structure of the present invention includes those molded into any shape. For example, plate-shaped, triangular prisms, polygons, cylinders, spheres, and network structures including many of these are also included. These molding methods can be performed by known methods such as cutting, hot pressing, and nonwoven fabric processing.

  In the network structure of the present invention, at least a part of the network structure includes the fine fiber main region, the thick fiber main region, and the mixture of the fine fiber main region and the thick fiber main region. The network structure including the region is also included. That is, the network structure of the present invention may include not only one fine fiber main region, one mixed region, and one thick fiber main region, but also a plurality of at least one of them. For example, the network structure of the present invention, in the thickness direction, a fine fiber main region, a mixed region, a thick fiber main region, a mixed region, and a network structure including a fine fiber main region, or a fine fiber main region, A network structure including a mixed region, a thick fiber main region, a mixed region, a fine fiber main region, a mixed region, and a thick fiber main region is also preferably included. Thus, even in a network structure in which at least one of a fine fiber main region and a thick fiber main region is present, from the viewpoint of having a soft tactile sensation at the time of use, less bottoming feeling, and excellent compression durability. A mixed region is preferably present between each fine fiber main region and each thick fiber main region. Furthermore, the network structure of the present invention requires that at least one surface side is a fine fiber main region side from the viewpoint of imparting a soft tactile sensation, and both surface sides are fine fiber main region sides. Good.

Apparent density of the network structure of the present invention is preferably 0.005 g / cm ³ or more 0.20 g / cm ³ or less, more preferably 0.01 g / cm ³ or more 0.18 g / cm ³ or less, 0.02 g / More preferably, it is not less than cm ^{3 and not} more than 0.15 g / cm ³ . Unsuitable cushioning material hardness is not be maintained, becomes too hard, exceeds 0.20 g / cm ³ in the opposite required when the apparent density is used as a cushioning material is less than 0.005 g / cm ³ It may become.

  The thickness of the network structure of the present invention is preferably 5 mm or more, and more preferably 10 mm or more. If the thickness is less than 5 mm, it may become too thin when used as a cushioning material, resulting in a feeling of bottoming. The upper limit of the thickness is preferably 300 mm or less, more preferably 200 mm or less, and still more preferably 120 mm or less, from the viewpoint of the production apparatus.

  The hardness at the time of 25% compression when pressed from the fine fiber main region side of the network structure of the present invention (when both surface sides are fine fiber main region sides, the fine fiber main region surface side consisting of finer fibers) is 10 N / φ100 mm or more is preferable, and 20 N / φ100 mm or more is more preferable. If the hardness at 25% compression is less than 10 N / φ100 mm, the hardness as a cushioning material may be insufficient and a feeling of bottoming may appear. The upper limit of the hardness at 25% compression is not particularly specified, but is preferably 1.5 kN / φ100 mm or less.

  40% compression hardness when pressed from the fine fiber main region side of the network structure of the present invention (when both surface sides are fine fiber main region sides, the fine fiber main region surface side consisting of finer fibers) 20 N / φ100 mm or more is preferable, 30 N / φ100 mm or more is more preferable, and 40 N / φ100 mm or more is more preferable. If the hardness at 40% compression is less than 20 N / φ100 mm, the hardness as a cushioning material may be insufficient and a feeling of bottoming may appear. The upper limit of the 40% compression hardness is not particularly specified, but is preferably 5 kN / φ100 mm or less.

  The hysteresis loss when pressed from the fine fiber main region side of the network structure of the present invention (the fine fiber main region surface side consisting of finer fibers when both surface sides are fine fiber main region sides) is 60%. Or less, more preferably 50% or less, further preferably 40% or less, particularly preferably 30% or less, and most preferably 25% or less. When the hysteresis loss exceeds 60%, the rebound of the network structure of the present invention is excessively lowered, and the sleeping comfort and the sitting comfort are deteriorated. The lower limit of the hysteresis loss is not particularly limited, but is preferably 1% or more in the present invention.

  In the present invention, after compression at 750 constant load when compressed from the fine fiber main region side (when both surface sides are the fine fiber main region side, the fine fiber main region surface side made of finer fibers). Residual strain, 25% and 40% compression hardness, and hysteresis loss were measured by Instron Universal Testing Machine manufactured by Instron Japan Company Limited, Precision Universal Testing Machine Autograph AG-X plus manufactured by Shimadzu Corporation, Orientec Co., Ltd. It can be measured using a universal testing machine such as Tensilon Universal Material Testing Machine.

  The cushion material of the present invention includes the above-described network structure inside the cushion. Since the cushion material according to the present invention includes the above-described network structure inside the cushion, the cushion material has a soft touch feeling during use, has a feeling of bottoming, and is excellent in compression durability.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The measurement and evaluation of the characteristic values in the examples were performed as follows. In addition, although the magnitude | size of a sample makes the standard the magnitude | size of the following as a standard, when the sample was insufficient, it measured using the sample size of the possible magnitude | size.

(1) Fiber diameter (mm)
A sample is cut into a size of 10 cm in the width direction, 10 cm in the length direction, and the thickness of the sample, and a linear body of ten fibers randomly from each of the fine fiber main region and the thick fiber main region in the thickness direction from the cut cross section. (A linear body is not collected from the mixed region. When there are a plurality of fine fiber main regions and / or large fiber main regions, 10 pieces are collected from each region.) Linear bodies were collected). The collected linear body was cut in a ring cutting direction, placed on a cover glass in a state standing in the fiber axis direction, and a fiber cross-sectional photograph in the ring cutting direction was obtained with an optical microscope set to an appropriate magnification. The diameter of the fiber which comprises each area | region was calculated | required from the obtained fiber cross-sectional photograph, and it was set as each fiber diameter. The average of the respective fiber diameters in each region was calculated to obtain the average value of the fiber diameters: unit mm (average value of each n = 10). When there are a plurality of fine fiber main regions and / or thick fiber main regions, and there are a plurality of average values of fiber diameters of thin fibers and / or average values of fiber diameters of thick fibers, the fiber lengths of the respective main regions The average value was obtained. Further, in the measurement of the fiber diameter in Comparative Example 2, a linear body of 10 fibers was randomly collected in the thickness direction from the cut cross section in a length of about 5 mm, and a cross-sectional photograph of the collected linear body was collected. The optical microscope was image | photographed with appropriate magnification, and the fiber diameter was calculated | required similarly to the above from the obtained fiber cross-sectional photograph. Since the surface of the network structure is flattened in order to obtain smoothness, the fiber cross section may be deformed. Therefore, a sample was not collected from an area within 2 mm from the surface of the network structure. In addition, when the cross-sectional shape of the linear body is a hollow cross-sectional shape or an irregular cross-sectional shape, the outer peripheral length of the cross-sectional shape of the linear body is obtained from the obtained fiber cross-sectional photograph, and a circle having an outer peripheral length equal to the outer peripheral length The diameter was determined by calculation, and the length was defined as the fiber diameter.

(2) Difference in fiber diameter (mm)
Taking the difference between the average values of the fiber diameters of the thin fiber and the thick fiber measured in (1) above,
(Difference in fiber diameter) = (Average value of fiber diameter of thick fibers) − (Average value of fiber diameter of thin fibers): Unit mm
The difference in fiber diameter was calculated by the following formula. In addition, when there are a plurality of fine fiber main regions and / or thick fiber main regions and an average value of fiber diameters of thick fibers and / or a plurality of average values of fiber diameters of thin fibers, (Average fiber diameter) is the largest (average fiber diameter of thick fibers), and (average fiber diameter of thin fibers) is the smallest (average fiber diameter of thin fibers). )It was adopted.

(3) Total weight ratio of thin fibers (%)
The sample was cut into a size of width 5 cm × length 5 cm × sample thickness. The fibers constituting the sample are confirmed visually or with an optical microscope or the like, and are divided into thin fibers and thick fibers. Thereafter, the total weight of only the thin fibers and the total weight of only the thick fibers are measured. The total weight ratio of thin fibers is
(Total weight ratio of thin fibers) = (total weight of thin fibers) / (total weight of thin fibers + total weight of thick fibers) × 100: unit%
It was calculated by the following formula.

(4) Hollow ratio (%)
The sample is cut into a size of 5 cm in the width direction × 5 cm in the length direction × the thickness of the sample, and the hollow cross-section fibers are randomly formed in the thickness direction from the cut cross section outside the range within 10% of the thickness direction from both sides of the sample surface. Ten bodies were collected. The collected linear body was cut in a ring cutting direction, placed on a cover glass in a state of being erected in the fiber axis direction, and a fiber cross-sectional photograph in the ring cutting direction was obtained with an optical microscope. Obtain the hollow area (a) and the total area (b) of the fiber including the hollow part from the cross-sectional photograph,
(Hollow rate) = (a) / (b) (unit%, average value of n = 10)
The hollow ratio was calculated by the following formula.

(5) Thickness and apparent density (mm and g / cm ³ )
Four samples were cut into a size of width 10 cm × length 10 cm × sample thickness, and left unloaded for 24 hours. Then, using a circular gauge probe with an area of 15 cm ² with a polymer instrument FD-80N thickness gauge with the fine fiber side facing up, the height of each sample was measured, and the average of four samples The value was calculated and taken as the thickness. Moreover, the average value of the weight of 4 samples which measured the said sample on the electronic balance was calculated | required, and it was set as the weight. Further, the apparent density is determined from the weight and thickness. (Apparent density) = (Weight) / (Thickness × 10 × 10): Unit g / cm ³
It was calculated by the following formula.

(6) Melting point (Tm) (° C)
An endothermic peak (melting peak) temperature was determined from an endothermic curve measured using a differential scanning calorimeter Q200 manufactured by TA Instruments Co., Ltd. at a heating rate of 20 ° C./min.

(7) Residual strain after repeated compression at 750 N constant load (%)
A sample is cut into a size of 40 cm in the width direction, 40 cm in the length direction, and the thickness of the sample, and left for 24 hours under no load in an environment of 23 ° C. ± 2 ° C., and then in a 23 ° C. ± 2 ° C. environment Measurements were made using a testing machine (Instron Universal Testing Machine manufactured by Instron Japan Company Limited). The fine fiber main region (when there are multiple fine fiber main regions, the fine fiber main region consisting mainly of the finest fibers, the same shall apply hereinafter) side of the pressure plate with a diameter of 200 mm and a thickness of 3 mm is the pressure plate side. Then, the sample was placed, and the thickness when the load was detected as 5 N was measured with a universal testing machine, and the thickness was determined as the initial hardness meter thickness (c). Thereafter, the sample whose thickness was measured was subjected to 750 N constant load repeated compression using ASKER STM-536 in accordance with JIS K6400-4 (2004) A method (constant load method). The pressure plate uses a circular plate with a radius of curvature of 25 ± 1 mm at the bottom edge, a diameter of 250 ± 1 mm, a thickness of 3 mm, and a flat bottom surface, a load of 750 ± 20 N, and a compression frequency of 70 ± 5 times per minute. The number of times of repeated compression was 80,000 times, and the time during which the maximum pressure was applied to 750 ± 20 N was 25% or less of the time required for repeated compression. After repeated compression, the test piece is left for 10 ± 0.5 minutes without applying force, and is added with a diameter of 200 mm and a thickness of 3 mm using a universal testing machine (Instron Universal Testing Machine manufactured by Instron Japan Company Limited). The sample was placed so that the platen was at the center of the sample, and the thickness when the load was detected as 5 N by a universal testing machine was measured, and the hardness meter thickness (d) after repeated compression was measured. The residual strain after repeated compression at 750 N constant load when pressurized from the fine fiber main region side is determined using the initial hardness meter thickness (c) and the hardness meter thickness after repeated compression (d),
(Residual strain after repeated compression at 750 N constant load)
= {(C)-(d)} / (c) × 100: Unit% (average value of n = 3)
It was calculated by the following formula.

(8) 25%, 40% compression hardness (N / φ100mm)
A sample is cut into a size of 20 cm in the width direction × 20 cm in the length direction × the thickness of the sample, left unloaded in an environment of 23 ° C. ± 2 ° C. for 24 hours, and then a universal test in an environment of 23 ± 2 ° C. Machine (Instron universal testing machine manufactured by Instron Japan Company Limited) main area of fine fiber so that the pressure plate is at the center of the sample (if there are multiple fine fiber main areas, the main area of fine fibers consisting mainly of the finest fibers) , The same applies hereinafter) Place the sample with the pressure plate side facing, and use a pressure plate with a diameter of 100 mm, a thickness of 25 ± 1 mm, a radius of curvature of 10 ± 1 mm at the bottom edge and a flat bottom surface, and a speed of 1 mm / min. Then, the compression was started, and the thickness when the load was detected as 0.4 N was measured with a universal testing machine to obtain the hardness meter thickness. The position of the pressure plate at this time is set to the zero point, and after compressing to 75% of the hardness meter thickness at a speed of 10 mm / min, the pressure plate is immediately returned to the zero point at a speed of 10 mm / min, and subsequently at a speed of 10 mm / min. Compressed to 25% and 40% of the hardness meter thickness, measured the load at that time, and determined the hardness at 25% compression and 40% compression hardness when pressed from the fine fiber main region side: unit N / φ100 mm (average value of n = 3).

(9) Hysteresis loss (%)
A sample is cut into a size of 20 cm in the width direction, 20 cm in the length direction, and the thickness of the sample, left in an environment of 23 ± 2 ° C. with no load for 24 hours, and then a universal test in an environment of 23 ° C. ± 2 ° C. Machine (Instron universal testing machine manufactured by Instron Japan Company Limited) main area of fine fiber so that the pressure plate is at the center of the sample (if there are multiple fine fiber main areas, the main area of fine fibers consisting mainly of the finest fibers) , The same applies hereinafter) Place the sample with the pressure plate side facing, and use a pressure plate with a diameter of 100 mm, a thickness of 25 ± 1 mm, a radius of curvature of 10 ± 1 mm at the bottom edge and a flat bottom surface, and a speed of 1 mm / min. Then, the compression was started, and the thickness when the load was detected as 0.4 N was measured with a universal testing machine to obtain the hardness meter thickness. The position of the pressure plate at this time was set to the zero point, and after compression to 75% of the hardness meter thickness at a speed of 10 mm / min, the pressure plate was immediately returned to the zero point at a speed of 10 mm / min (the first stress strain) curve). When it returned to the zero point, it was again compressed to 75% of the hardness meter thickness at a speed of 10 mm / min, and immediately returned to the zero point at the same speed (second stress strain curve).

In the second stress strain curve of FIG. 1A, the compression energy (WC) indicated by the second compression stress curve of FIG. 1B and the second decompression stress curve of FIG. The following formula (hysteresis loss) = (WC−WC ′) / WC × 100: unit%
WC = ∫PdT (Work amount when compressed from 0% to 75%)
WC ′ = ∫PdT (Work amount when decompressing from 75% to 0%)
Accordingly, the hysteresis loss when pressing was performed from the fine fiber main region (in the case where there are a plurality of fine fiber main regions, the fine fiber main region mainly composed of the thinnest fibers, hereinafter the same) was determined.

  The hysteresis loss can be simply calculated by data analysis using a personal computer when a stress strain curve as shown in FIG. 1 is obtained, for example. Also, the area of the shaded portion can be determined as WC, and the area of the shaded portion can be determined as WC ′, and the difference between these areas can be obtained from the weight of the portion cut out (average value of n = 3).

(10) Bottom feeling A sample was cut into a size of 40 cm in the width direction, 40 cm in the length direction, and the thickness of the sample, and 30 panelists (male aged 20 to 39 years old) having a body weight in the range of 40 kg to 100 kg. 5, 20-39-year-old women: 5, 40-59-year-old men: 5, 40-59-year-old women: 5, 60- to 80-year-old men: 5, 60-year-old 80-year-old woman: 5) sits on a chair and sits from the side of the fine fiber main region (if there are multiple fine fiber main regions, the fine fiber main region consisting mainly of the finest fibers, the same applies hereinafter) The degree of feeling of “Donsun” hitting the seat of the chair was qualitatively evaluated. The evaluation criteria were as follows: No feeling; ◎, weak feeling; ○, moderate feeling; Δ, strong feeling;

[Example 1]
Polyester thermoplastic elastomer containing dimethyl terephthalate (DMT) and 1,4-butanediol (1,4-BD) with a small amount of catalyst, transesterified by a conventional method, and having a number average molecular weight of 1,000 Tetramethylene glycol (PTMG) was added and polycondensed while raising the temperature and pressure to form a polyetherester block copolymer elastomer. Then, 1% of antioxidant was added, mixed, kneaded, pelletized, The polyester-based thermoplastic elastomer A-1 was obtained by vacuum drying for a period of time. Polyester thermoplastic elastomer A-1 had a soft segment content of 40% by weight and a melting point of 198 ° C.

  Thickness fiber with a length of 50cm in the width direction and a length of 67.6mm in the thickness direction. The orifice shape is 3mm outer diameter in the first to seventh rows in the thickness direction, 2.6mm in inner diameter, and a thick triple bridge fiber. The hollow forming orifices for use are made in a staggered arrangement with a pitch between the holes in the width direction of 6 mm and a pitch between the holes in the thickness direction of 5.2 mm, and the solid forming orifices for thin fibers with an outer diameter of 1 mm in the 8th to 14th rows in the thickness direction. The obtained polyester-based thermoplastic elastomer (A-1) was used at a spinning temperature (melting temperature) of 240 ° C. using a nozzle having a staggered arrangement with a pitch between holes in the width direction of 6 mm and a pitch between holes in the thickness direction of 5.2 mm. A single hole discharge rate of 1.4 g / min for a hollow forming orifice hole and a single hole discharge amount of 0.8 g / min for a solid forming orifice hole is discharged below the nozzle, and cooling water is arranged under the nozzle surface 26 cm, 60cm A pair of take-up conveyor nets are arranged in parallel so that the endless nets made by Ness are spaced at intervals of 52 mm in the opening width so as to partially protrude on the water surface, and the molten discharge line is twisted on the conveyor net on the water surface. A loop is formed to form a three-dimensional network structure while fusing the contact portions, and both sides of the molten network structure are taken up by a conveyor net and taken into cooling water at a take-up speed of 1.14 m / min. The both sides in the thickness direction were flattened by drawing and solidifying, and then cut into a predetermined size and dried and heat-treated with 110 ° C. hot air for 15 minutes to obtain a network structure.

The obtained network structure has a fine fiber main region mainly made of solid cross-section fibers having a fiber diameter of 0.48 mm, and a cross-sectional shape mainly having a fiber diameter of 0.73 mm is a triangular rice ball type with a hollow ratio of 20%. A thick fiber main region composed of hollow cross-section fibers, and a mixed region in which a thin fiber and a thick fiber are mixed between the fine fiber main region and the thick fiber main region. A network structure integrated without separation, with a difference in fiber diameter of 0.25 mm, a total weight ratio of thin fibers of 35%, an apparent density of 0.050 g / cm ³ , and a flattened surface thickness Was 50 mm.

  With respect to the obtained network structure, the residual strain after repeated compression at 750 N constant load when pressurized from the fine fiber main region side is 7.0%, 25% compression hardness is 28.9 N / φ100 mm, 40% compression The time hardness was 55.7 N / φ100 mm, the hysteresis loss was 26.7%, the feeling of bottoming by the panel was not felt, and the evaluation was ◎. The results are summarized in Table 1.

  As shown in Table 1, in the network structure obtained in this example, the fiber diameter of the thin fibers is 0.1 mm or more and 1.5 mm or less, and the total weight ratio of the thin fibers is 10% or more and 90%. Since it was the following, it had a soft touch. In addition, the network structure obtained in this example has a fiber diameter of 0.07 mm or more larger than the fiber diameter of the thin fiber, and 25% when pressurized from the fine fiber main region side. Since the hardness at the time of compression was 10 N / φ100 mm or more and the hardness at the time of 40% compression was 20 N / φ100 mm or more, there was no feeling of bottoming in the qualitative evaluation by the panel feeling of bottoming. In addition, the network structure obtained in this example has a mixed region between the fine fiber main region and the thick fiber main region, and after repeated compression at a constant load of 750 N when pressurized from the fine fiber main region side. Since the residual strain was 15% or less, the compression durability was excellent.

[Example 2]
Thickness fiber with a length of 50cm in the width direction and a length of 67.6mm in the thickness direction. The orifice shape is 3mm outer diameter in the first to seventh rows in the thickness direction, 2.6mm in inner diameter, and a thick triple bridge fiber. The hollow forming orifice for use is a staggered arrangement with a pitch between the holes in the width direction of 6 mm and a pitch between the holes in the thickness direction of 5.2 mm. The solid formation for thin fibers with an outer diameter of 1.2 mm in the 8th to 13th rows in the thickness direction The polyester thermoplastic elastomer (A-1) obtained above was spun at a spinning temperature (melting temperature) using a nozzle in which the orifices had a staggered arrangement of 7 mm in the width direction hole pitch and 6.1 mm in the thickness direction hole pitch. At a temperature of 240 ° C., a single-hole discharge rate of 1.2 g / min for the hollow forming orifice hole, and a single-hole discharge rate of 1.0 g / min for the solid forming orifice hole, and cooling water is disposed 28 cm below the nozzle surface. Width 60 The stainless steel endless nets are arranged in parallel so that a part of the pair of take-up conveyor nets protrudes on the water surface at intervals of 52 mm in opening width, and the molten discharge line is bent on the conveyor net on the water surface. A kneading loop is formed to form a three-dimensional network structure while fusing the contact portions, and both sides of the molten network structure are taken up and sandwiched between conveyor nets and cooled at a take-up speed of 1.14 m / min. After drawing into water and solidifying, both sides in the thickness direction were flattened, then cut into a predetermined size and dried and heat-treated with 110 ° C. hot air for 15 minutes to obtain a network structure.

The obtained network structure has a fine fiber main region mainly made of solid cross-section fibers with a fiber diameter of 0.63 mm, and a triangular shape with a cross-sectional shape of a fiber diameter of 0.70 mm and a hollow ratio of 18%. A thick fiber main region composed of hollow cross-section fibers, and a mixed region in which a thin fiber and a thick fiber are mixed between the fine fiber main region and the thick fiber main region. A network structure integrated without separation, with a difference in fiber diameter of 0.07 mm, a total weight ratio of thin fibers of 45%, an apparent density of 0.046 g / cm ³ , and a flattened surface thickness Was 50 mm.

  About the obtained network structure, when pressed from the fine fiber main region side, the residual strain after repeated compression at a constant load of 750 N is 7.2%, the hardness at 25% compression is 39.4 N / φ100 mm, 40% compression The time hardness was 68.4 N / φ100 mm, the hysteresis loss was 23.1%, the feeling of bottoming by the panel was not felt, and the evaluation was ◎. The results are summarized in Table 1.

  As shown in Table 1, in the network structure obtained in this example, the fiber diameter of the thin fibers is 0.1 mm or more and 1.5 mm or less, and the total weight ratio of the thin fibers is 10% or more and 90%. Since it was the following, it had a soft touch. In addition, the network structure obtained in this example has a fiber diameter of 0.07 mm or more larger than the fiber diameter of the thin fiber, and 25% when pressurized from the fine fiber main region side. Since the hardness at the time of compression was 10 N / φ100 mm or more and the hardness at the time of 40% compression was 20 N / φ100 mm or more, there was no feeling of bottoming in the qualitative evaluation by the panel feeling of bottoming. In addition, the network structure obtained in this example has a mixed region between the fine fiber main region and the thick fiber main region, and after repeated compression at a constant load of 750 N when pressurized from the fine fiber main region side. Since the residual strain was 15% or less, the compression durability was excellent.

[Example 3]
The orifice shape on the nozzle effective surface of 50 cm in the width direction and 72.7 mm in the thickness direction is the width of the solid forming orifice for thin fibers with an outer diameter of 1 mm in the first to fourth rows in the thickness direction. Hollow forming orifices for thick triple bridge fibers with an outer diameter of 3 mm and an inner diameter of 2.6 mm in the 5th to 11th rows in the thickness direction, with a staggered arrangement of 6 mm pitch between holes in the direction and 5.2 mm pitch between holes in the thickness direction Is a staggered array with a width-direction hole pitch of 6 mm and a thickness-direction hole pitch of 5.2 mm, and the solid-form orifices for thin fibers with an outer diameter of 1 mm are arranged in the 12th to 15th rows in the thickness direction. Using a nozzle having a staggered arrangement of 6 mm and a pitch between holes in the thickness direction of 5.2 mm, the polyester-based thermoplastic elastomer (A-1) obtained above is hollow at a spinning temperature (melting temperature) of 240 ° C. Forming orifice hole Made of stainless steel with a single hole discharge rate of 1.5 g / min and a solid orifice orifice with a single hole discharge rate of 0.9 g / min. A pair of take-up conveyor nets are arranged in parallel so that the endless nets are spaced at intervals of 52 mm in the opening width so as to partially protrude on the water surface, and the discharge line shape in the molten state is twisted on the conveyor net on the water surface. Forming a three-dimensional network structure while fusing the contact part to form a loop, drawing the both sides of the molten network structure into the cooling water at a take-up speed of 1.54 m / min while being sandwiched between conveyor nets, After solidifying, both surfaces in the thickness direction were flattened, then cut to a predetermined size and dried and heat-treated with 110 ° C. hot air for 15 minutes to obtain a network structure.

The obtained network structure has, in the thickness direction, a fine fiber main region mainly composed of thin fibers, a mixed region composed of thin fibers and thick fibers, and a thick fiber main region mainly composed of thick fibers. And a mixed region composed of thin fibers and thick fibers and a fine fiber main region mainly composed of thin fibers in this order, and these regions are integrated without separation. A thick fiber is a hollow cross section having a triangular rice ball type cross section, a hollow linear body having a hollow ratio of 20% and a fiber diameter of 0.70 mm, and a thin fiber having a fiber diameter of 0.50 mm. It is formed of a solid wire, the difference in fiber diameter is 0.20 mm, the total weight ratio of thin fibers is 40%, the apparent density is 0.040 g / cm ³ , and the flattened thickness is 51 mm. It was. Here, since the network structure obtained in this example is a fine fiber main region mainly composed of thin fibers on both surface layers, the fine fiber main region composed mainly of the finest fibers is selected and Measurement was performed by applying pressure from the region side.

  About the obtained network structure, residual pressure after repeated compression at 750 N constant load when pressed from the fine fiber main region side is 7.1%, hardness at 25% compression is 18.0 N / φ100 mm, 40% compression The time hardness was 35.7 N / φ100 mm, the hysteresis loss was 26.0%, and the feeling of bottoming by the panel was not felt, and the evaluation was ◎. The results are summarized in Table 1.

  As shown in Table 1, in the network structure obtained in this example, the fiber diameter of the thin fibers is 0.1 mm or more and 1.5 mm or less, and the total weight ratio of the thin fibers is 10% or more and 90%. Since it was the following, it had a soft touch. In addition, the network structure obtained in this example has a fiber diameter of 0.07 mm or more larger than the fiber diameter of the thin fiber, and 25% when pressurized from the fine fiber main region side. Since the hardness at the time of compression was 10 N / φ100 mm or more and the hardness at the time of 40% compression was 20 N / φ100 mm or more, there was no feeling of bottoming in the qualitative evaluation by the panel feeling of bottoming. In addition, the network structure obtained in this example has a mixed region between the fine fiber main region and the thick fiber main region, and after repeated compression at a constant load of 750 N when pressurized from the fine fiber main region side. Since the residual strain was 15% or less, the compression durability was excellent.

[Comparative Example 1]
Using the obtained polyester-based thermoplastic elastomer (A-1), one row on a nozzle effective surface having a spinning temperature (melting temperature) of 240 ° C., a length in the width direction of 50 cm, and a length in the thickness direction of 67.6 mm. To 8 rows, the orifice shape is 3mm outside diameter, 2.6mm inside diameter, and the hollow forming orifice for thick triple bridge fibers is staggered with a 10mm width-to-hole pitch and 7.5mm thickness-to-hole pitch. In the 9th to 11th rows, a solid-forming orifice for thin fibers having an outer diameter of 0.7 mm is used, and a nozzle having a widthwise hole pitch of 2.5 mm and a thicknesswise hole pitch of 3.7 mm is used. A single hole discharge rate of 2.0 g / min for hollow forming orifice holes, a single hole discharge amount of solid forming orifice holes of 0.5 g / min, and a total discharge rate of 1100 g / min are discharged downward from the nozzle, and nozzle surface 18c Cooling water is placed underneath, and a stainless steel endless net having a width of 60 cm is arranged in parallel so that a pair of take-up conveyor nets are partly exposed on the water surface at an opening width interval of 50 mm, on the conveyor net on the water surface, The molten discharge line is twisted to form a loop to form a three-dimensional network structure while fusing the contact portions, and both sides of the molten network structure are taken up and sandwiched between conveyor nets 1 After being drawn into cooling water at a take-up speed of 0.000 m / min and solidified, it was cut into a predetermined size and subjected to a drying heat treatment with hot air at 110 ° C. for 15 minutes to obtain a network structure.

  The obtained network structure was a network structure in which the fine fiber main region mainly composed of thin fibers and the thick fiber main region mainly composed of thick fibers were integrated without being separated. In the obtained network structure, the pitch between the wide fibers in the width direction of the thick fiber forming orifice and the pitch between the holes in the width direction of the thin fiber forming orifice are very different from each other. It was a network structure in which there was no region where the thickness was formed by mixing thin fibers and thick fibers.

A thick fiber is a hollow cross section having a triangular rice cake type cross section, and is formed of a hollow linear body having a hollow ratio of 28% and a fiber diameter of 0.80 mm. A thin fiber is a solid line having a fiber diameter of 0.32 mm. The difference in fiber diameter was 0.48 mm, the total weight ratio of thin fibers was 27%, the apparent density was 0.046 g / cm ³ , and the flattened thickness of the surface was 50 mm.

  About the obtained network structure, when pressed from the fine fiber main region side, the residual strain after repeated compression at 750 N constant load is 15.6%, the hardness at 25% compression is 21.9 N / φ100 mm, 40% compression The time hardness was 40.3 N / φ100 mm, the hysteresis loss was 23.8%, the feeling of bottoming by the panel was not felt, and the evaluation was ◎. The results are summarized in Table 1.

  As shown in Table 1, the network structure obtained in this comparative example had a compression endurance of more than 15% after 750 N constant load repeated compression when pressurized from the fine fiber main region side. The nature was bad.

[Comparative Example 2]
The shape of the orifice on the nozzle effective surface with a length of 100 cm in the width direction and a length of 31.2 mm in the thickness direction is a triple bridge hollow forming cross section with 7 rows in the thickness direction and an outer diameter of 3 mm and an inner diameter of 2.6 mm. The obtained polyester-based thermoplastic elastomer (A-1) was set to a spinning temperature (melting temperature) of 240 ° C. using a nozzle in which the orifices were arranged in a staggered arrangement with a pitch between the holes in the width direction of 6 mm and a pitch between the holes in the thickness direction of 5.2 mm. Then, a single-hole discharge rate of 1.5 g / min is discharged below the nozzle, cooling water is arranged under the nozzle surface 28 cm, and a pair of take-up conveyors with a stainless steel endless net having a width of 200 cm in parallel with an opening width of 27 mm. Is arranged so as to partially protrude on the water surface, and the molten discharge line is twisted on the conveyor net on the water surface to form a loop to fuse the contact portion. A three-dimensional network structure is formed, and both sides of the molten network structure are drawn into the cooling water at a take-up speed of 1.14 m / min while being sandwiched between take-up conveyors, and both sides in the thickness direction are flattened by solidifying. Then, it cut | disconnected to the predetermined | prescribed magnitude | size and dried and heat-processed for 15 minutes with 110 degreeC hot air, and obtained the network structure which a cross-sectional shape mainly consists of a hollow cross-section fiber. The network structure thus obtained had an apparent density of 0.063 g / cm ³ , a flattened surface thickness of 25 mm, a hollow cross-section fiber having a hollowness of 20% and a fiber diameter of 0.76 mm. .

In addition, the shape of the orifice on the nozzle effective surface with a width direction of 100 cm and a thickness direction width of 31.2 mm is 7 mm in the thickness direction, a solid forming orifice with an outer diameter of 1 mm, and a width-direction hole pitch of 6 mm, between the holes in the thickness direction. Using a staggered nozzle with a pitch of 5.2 mm, the obtained thermoplastic elastic resin (A-1) was discharged below the nozzle at a melting temperature of 240 ° C. and a single hole discharge rate of 0.9 g / min. , Distributing cooling water below the 28cm nozzle surface, and arranging a 200cm wide stainless steel endless net in parallel with a pair of take-up conveyors at intervals of opening width of 27mm on the water surface. A three-dimensional network structure is formed by twisting the discharge line shape in the molten state to form a loop while fusing the contact portions, and both sides of the molten network structure are picked up and sandwiched between conveyors. While drawing it into cooling water at a take-up speed of 1.14 m / min and flattening both sides in the thickness direction by solidifying, cut to a predetermined size and dry heat-treat with hot air at 110 ° C. for 15 minutes A network structure mainly composed of solid cross-section fibers was obtained. The resulting network structure had an apparent density of 0.038 g / cm ³ , a flattened thickness of 25 mm, and a solid cross-section fiber having a fiber diameter of 0.50 mm.

The obtained network structure composed of solid cross-section fibers, which are mainly thin fibers, and network structure composed of hollow cross-section fibers, which are mainly thick fibers, were overlapped to create a network structure. The apparent density of the entire laminated network structure was 0.051 g / cm ³ and the thickness was 50 mm. The difference between the fiber diameter of the hollow cross-section fiber, which is a thick fiber, and the fiber diameter of the solid cross-section fiber, which is a thin fiber, was 0.26 mm.

  With respect to this overlapped network structure, the residual strain after repeated compression at a constant load of 750 N is 17.3% and the hardness when compressed is 32. 32. 1N / φ100 mm, 40% hardness at compression 61.3 N / φ100 mm, hysteresis loss 26.2%, no feeling of bottoming due to panelists was felt, and evaluation was ◎. The results are summarized in Table 1.

  As shown in Table 1, the overlap network structure obtained in this comparative example had a residual strain after repeated compression at 750 N constant load when pressed from the network structure side made of fine fibers, greater than 15%. Therefore, the compression durability was bad.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The network structure of the present invention is a network structure that satisfies all the three characteristics of having a soft tactile sensation during use, low bottoming feeling, and excellent compression durability, such as an office chair, furniture, sofa, bed, etc. Can provide a net-like structure suitable for cushioning materials used in bedding, vehicle seats such as trains, automobiles, two-wheeled vehicles, strollers, and child seats, floor mats, and mats for shock absorption such as collision and pinching prevention members. It is great to contribute to the industry.

Claims (5)

A network structure having a three-dimensional random loop joining structure composed of a continuous line of thermoplastic elastomer,
A fine fiber main region mainly composed of fine fibers having a fiber diameter of 0.1 mm to 1.5 mm and a thick fiber having a fiber diameter of 0.4 mm to 3.0 mm in the thickness direction of the network structure. A thick fiber main region, and a mixed region formed by mixing the thin fiber and the thick fiber located between the fine fiber main region and the thick fiber main region,
The fiber diameter of the thick fiber is 0.07 mm or more thick compared to the thin fiber,
A network structure having a residual strain of 15% or less after repeated compression at a constant load of 750 N when pressurized from the fine fiber main region side of the network structure. The apparent network structure according to claim 1 density of 0.005 g / cm ³ or more 0.20 g / cm ³ or less.   The network structure according to claim 1 or 2, wherein the thin fibers are solid cross-section fibers having a solid cross section, and the thick fibers are hollow cross-section fibers having a hollow cross section.   The network structure according to any one of claims 1 to 3, wherein a hysteresis loss when the network structure is pressed from the fine fiber main region side is 60% or less.   A cushioning material comprising the network structure according to any one of claims 1 to 4 inside the cushion.

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