Mesh structure made from recycled materials

Abstract

This invention provides a mesh structure that can suppress unpleasant odors and offers excellent moldability and durability. [Solution] A mesh structure composed of multiple strands, wherein each strand contains 49-99% by weight of a thermoplastic elastomer (A), 0.89-50% by weight of a polyethylene resin (B) derived from recovered material of a mesh structure, 0.1-3.0% by weight of a zeolite (C), and 0.01-0.5% by weight of an antioxidant (D).

Description

[Technical Field]

[0001] This invention relates to a mesh structure made from recycled materials. [Background technology]

[0002] In recent years, environmental pollution caused by plastics has become a major concern, and the material recycling of plastic products is being promoted.

[0003] Generally, the process of reusing waste plastic to obtain recycled products includes washing, dewatering, crushing, repelling, and molding of the collected waste plastic. However, when the waste plastic is collected from used plastic products, impurities other than the raw materials that make up the product often remain even after the washing process. For this reason, recycled products using recycled plastic materials as raw materials may contain impurities. Examples of impurities contained in recycled products include aldehydes and organic carboxylic acids, which not only generate odors that cause discomfort to users but also have the problem of reducing the moldability during the manufacturing of molded products.

[0004] Against this backdrop, various technologies have been considered to mitigate the effects of impurities contained in recycled products. For example, a method has been proposed to suppress the generation of hydrochloric acid by adding acid acceptors such as magnesium oxide or hydrotalcite to waste plastics containing polyvinyl chloride resin, such as plastic container packaging waste and other general plastic product waste (see, for example, Patent Document 1). In addition, a recycled resin container with less odor has been proposed by adding an adsorbent such as zeolite to a multilayer plastic container containing a recycled resin layer of polyolefin-based packaging container to adsorb hydrocarbon volatiles generated by thermal degradation (see, for example, Patent Document 2).

[0005] However, Patent Document 1 deals with methods for suppressing hydrochloric acid generated during the manufacturing process of recycled products, and does not address methods for suppressing odors containing aldehydes and organic acids in recycled products. Furthermore, Patent Document 2 deals with methods for reducing odors containing hydrocarbon volatiles generated by thermal degradation, and does not address methods for suppressing odors containing aldehydes and organic acids in recycled products. In addition, Patent Documents 1 and 2 do not address the moldability of recycled products. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 4828836 [Patent Document 2] Japanese Patent Publication No. 1995-33172 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention aims to provide a mesh structure that can suppress unpleasant odors and has excellent moldability and durability. [Means for solving the problem]

[0008] As a result of diligent research to solve the aforementioned problems, the present inventors have found that by giving the strands constituting the mesh structure a predetermined composition, even when using recovered mesh structure material as a raw material, it is possible to suppress unpleasant odors derived from the recovered material and provide a mesh structure with excellent moldability and durability, thus completing the present invention.

[0009] In other words, the gist of this invention is as follows: [1] The present invention relates to a mesh structure composed of a plurality of strands, wherein each strand comprises 49 to 99% by weight of a thermoplastic elastomer (A), 0.89 to 50% by weight of a polyethylene resin (B) derived from recovered material of a mesh structure, 0.1 to 3.0% by weight of a zeolite (C), and 0.01 to 0.5% by weight of an antioxidant (D). [2] The mesh structure is a three-dimensional loop-jointed structure formed by joining together loop-shaped strands having a fiber diameter of 0.1 mm or more and 3.0 mm or less, and the apparent density of the mesh structure is 0.005 g / cm³. 3 More than 0.20g / cm 3 The mesh structure according to [1], wherein the bonding strength between the strands is 25N or more. [3] The thermoplastic elastomer (A) has a density of 940 kg / m³ 3 The network structure according to [1], characterized by being the following ethylene-α-olefin copolymer. [4] The density of the ethylene-α-olefin copolymer is 915 kg / m³ 3 The mesh structure according to [3], characterized in that, in the melting curve of the mesh structure measured using a differential scanning calorimeter, there is one endothermic peak in the range of 80°C to 110°C, and two or more endothermic peaks in the range of less than 80°C. [5] The network structure according to [1], wherein the zeolite (C) is two or more types of zeolites. [6] The network structure according to [1], wherein the antioxidant (D) is a phosphorus-based antioxidant. [7] A method for manufacturing a mesh structure, comprising the steps of forming strands from a molten mixture containing 49-99% by weight of a thermoplastic elastomer (A), 0.89-50% by weight of a polyethylene resin (B) derived from recovered mesh structures, 0.1-3.0% by weight of a zeolite (C), and 0.01-0.5% by weight of an antioxidant (D), and bringing the strands into contact with each other in a molten state. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress unpleasant odors and provide a network structure excellent in molding processability and durability. Therefore, the network structure of the present invention is suitable for, for example, office chairs, furniture, sofas, bedding such as beds, and vehicle seats such as trains, automobiles, and motorcycles.

Brief Description of the Drawings

[0011] [Figure 1] FIG. 1 is a diagram for explaining a random loop structure (a) and a honeycomb loop structure (b).

Embodiments for Carrying Out the Invention

[0012] Hereinafter, an embodiment of the present invention will be described in detail.

[0013] This embodiment relates to a network structure composed of a plurality of strands. The strands constituting the network structure (hereinafter, also referred to as "strands according to this embodiment") include 49 to 99% by weight of a thermoplastic elastomer (A), 0.89 to 50% by weight of polyethylene derived from the recovered material of the network structure, 0.1 to 3.0% by weight of zeolite (C), and 0.01 to 0.5% by weight of an antioxidant (D).

[0014] In the strands according to this embodiment, since the thermoplastic elastomer (A) forms a network structure with excellent molding processability and durability, the density is 940 kg / m 3 It is preferably the following ethylene-α-olefin copolymer. As the ethylene-α-olefin copolymer, it is preferable to use an ethylene-α-olefin copolymer composed of ethylene and an α-olefin having 3 or more carbon atoms. Among such ethylene-α-olefin copolymers, the density is 860 to 940 kg / m 3 It is preferably an ethylene-α-olefin copolymer, and more preferably an ethylene-α-olefin copolymer described in the pamphlet of JP-A-6-293813.

[0015] The density of thermoplastic elastomer (A) can be determined by extruding a sample at 190°C under a load of 21.2N, allowing it to cool slowly for 5 minutes, and then measuring the density using the density gradient tube method in accordance with JIS K6760 (1995). The temperature of the density gradient tube can be set to 23°C.

[0016] An ethylene-α-olefin copolymer, consisting of ethylene and an α-olefin having 3 or more carbon atoms, is a copolymer of ethylene and an α-olefin having 3 or more carbon atoms. Examples of α-olefins having 3 or more carbon atoms that copolymerize with ethylene 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, and 1-eicosene. Preferably, the α-olefin having 3 or more carbon atoms that copolymerize with ethylene may be one type or two or more types may be used. These α-olefins are typically copolymerized in an amount of 1% to 40% by weight relative to 100% by weight of the ethylene-α-olefin copolymer.

[0017] Ethylene-α-olefin copolymers may be used commercially (for example, Nipolon-Z 15P51B manufactured by Tosoh Corporation), but they can also be produced by copolymerizing ethylene and α-olefin using a catalyst system that has a specific metallocene compound and an organometallic compound as its basic components.

[0018] In the strand according to this embodiment, the content of thermoplastic elastomer (A) may be 49 to 99% by weight relative to 100% by weight of the strand according to this embodiment, but it is more preferable to be 69.89 to 99% by weight, as this results in a mesh structure with superior moldability and durability (especially strength).

[0019] In this embodiment, it is preferable that the mesh structure has an endothermic peak below the melting point of the thermoplastic elastomer (A) in the melting curve (endothermic curve) of the mesh structure measured using a differential scanning calorimeter. The mesh structure of this embodiment having an endothermic peak below the melting point of the thermoplastic elastomer (A) exhibits significantly improved durability (particularly heat resistance and deformation resistance) compared to a mesh structure that does not have an endothermic peak below the melting point of the thermoplastic elastomer (A). From the viewpoint of further improving durability (particularly heat resistance and deformation resistance), the mesh structure of this embodiment uses a thermoplastic elastomer (A) with a density of 915 kg / m³. 3 Preferably, the following ethylene-α-olefin copolymer is used, and the melting curve measured using a differential scanning calorimeter has one endothermic peak in the range of 80°C to 110°C, and two or more endothermic peaks in the range of less than 80°C, which is lower than the melting point of the ethylene-α-olefin copolymer, 99°C. In the ethylene-α-olefin copolymer used as the thermoplastic elastomer (A) in this embodiment, for example, has a density of 915 kg / m³. 3 The following ethylene-1-hexene copolymers (for example, trade name: Nipolon-Z 15P51B, manufactured by Tosoh Corporation) can be cited. In the melting curve of the mesh structure of this embodiment measured using a differential scanning calorimeter, the temperature (position) of the endothermic peak can be adjusted by the strand composition. Furthermore, the melting point of thermoplastic elastomer (A) refers to the temperature of the melting peak in the melting curve of thermoplastic elastomer (A) measured using a differential scanning calorimeter.

[0020] Furthermore, the presence of an endothermic peak within a specified temperature range means that there is an endothermic peak with a peak top within that specified temperature range. Also, measurements using a differential scanning calorimeter (for example, the DSC7000X manufactured by Hitachi High-Tech Science Corporation) to obtain the melting curve should be performed at a heating rate of 10°C / min.

[0021] The preferred thermoplastic elastomer (A), an ethylene-1-hexene copolymer, may be a commercially available product (for example, trade name: Nipolon-Z 15P51B, manufactured by Tosoh Corporation), or it may be produced by copolymerizing ethylene and 1-hexene using a metallocene compound as a catalyst in a known manner. By reducing the amount of 1-hexene copolymerized, the crystalline structure constrains the molecular chains, further improving the durability (especially heat resistance and fatigue resistance) of the ethylene-α-olefin copolymer.

[0022] In the strand according to this embodiment, the polyethylene resin (B) is derived from recovered mesh structures. Here, "derived from recovered mesh structures" means that used mesh structures are used as raw materials. For example, if polyethylene resin contained in a used mesh structure is used as the polyethylene resin (B), then it can be said that the polyethylene resin (B) is derived from recovered mesh structures. From the viewpoint of promoting material recycling, it is preferable that the recovered mesh structures are waste materials recovered from used mesh structures.

[0023] The recovered mesh structures are not particularly limited in their collection destination. For example, recovered mesh structures used in automobile and railway seats or chairs, sofas, sheets, gloves, container lids, bottles, cups, trays, and tubes may be used, and two or more types may be used. The recovered mesh structures only need to contain polyethylene resin, but may also contain other components besides polyethylene resin. Such other components include resins other than polyethylene resin contained in the mesh structures, deposits that adhere to the mesh structures during use, and other waste-derived substances that become mixed in during the recovery process of the mesh structures.

[0024] As described later, the strand according to this embodiment uses recovered mesh structure material as a manufacturing raw material. Therefore, the strand according to this embodiment may contain not only polyethylene resin derived from the recovered mesh structure material, but also other components other than polyethylene resin derived from the recovered mesh structure material. In the strand according to this embodiment, the content of other components other than polyethylene resin derived from the recovered mesh structure material is preferably 0.01 to 0.50% by weight based on 100% by weight of the strand.

[0025] Examples of polyethylene-based resins (B) derived from recovered mesh structures include polyethylene, ethylene-α-olefin copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, and ethylene vinyl acetate copolymer, and one or more of these can be used. Among the resins mentioned above, it is preferable that the polyethylene-based resin (B) derived from recovered mesh structures is one or more resins selected from the group consisting of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, and ethylene vinyl acetate copolymer, as these result in a mesh structure with superior moldability and durability.

[0026] Furthermore, the polyethylene-based resin (B) derived from the recovered material of the mesh structure may be the same type of thermoplastic elastomer as thermoplastic elastomer (A), or a different type of thermoplastic elastomer may be used. However, when using a thermoplastic elastomer as the polyethylene-based resin (B) derived from the recovered material of the mesh structure, it is preferable to use the same type of thermoplastic elastomer as thermoplastic elastomer (A).

[0027] In the strand according to this embodiment, the content of polyethylene resin (B) derived from the recovered mesh structure may be 0.89 to 50% by weight relative to 100% by weight of the strand according to this embodiment, but it is preferably 0.89 to 30% by weight, as this results in a mesh structure with excellent moldability and durability (especially strength). If the content of polyethylene resin (B) derived from the recovered mesh structure exceeds 50% by weight, the durability (especially resistance to deformation) of the mesh structure may be poor, or the odor suppression performance may not be sufficiently exhibited. Furthermore, a content of less than 0.89% by weight is undesirable from the viewpoint of recyclability.

[0028] In the strand according to this embodiment, the zeolite (C) is not limited to any type as long as it is referred to as zeolite, and examples include natural zeolite, synthetic zeolite, and artificial zeolite. The structure (skeletal structure) of zeolite (C) is not particularly limited, but examples include FAU type, LTA type, MFI type, MOR type, BEA type, LTL type, FER type, or MWW type zeolite, and among these, it is preferable to include FAU type zeolite because it results in a network structure that can suppress odors more effectively. FAU type zeolite is considered to have superior physical adsorption properties for odors because it has a larger pore size compared to zeolites with other skeletal structures. Furthermore, zeolite (C) may contain two or more types of zeolites with different skeletal structures, and by combining two or more types of zeolites with different skeletal structures, a network structure with particularly low odor can be obtained.

[0029] In the strand according to this embodiment, the particle size of the zeolite (C) is not particularly limited. However, from the viewpoints of the appearance of the network structure, the molding processability, and the mechanical properties, the average particle size is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 5 μm or less. The lower limit value of the average particle size of the zeolite (C) in this embodiment is not particularly limited, and for example, it may be 0.3 μm or more. The average crystal particle size of the zeolite (C) can be obtained by measuring the horizontal Feret diameter of 150 or more primary crystal particles in a scanning electron microscope observation and averaging them.

[0030] In the strand according to this embodiment, from the viewpoint of further suppressing odor, the BET specific surface area of the zeolite (C) is 100 m 2 / g or more and 800 m 2 / g or less, preferably 300 m 2 / g or more and 800 m 2 / g or less. The BET specific surface area of the zeolite (C) can be obtained by applying the BET method to the adsorption result of nitrogen gas measured by a general nitrogen gas adsorption method.

[0031] In the strand according to this embodiment, since the zeolite (C) forms a network structure that can further suppress odor, the counter ion (counter cation) for compensating the charge of the framework structure is preferably one or more cations selected from the group consisting of hydrogen ion, sodium ion, potassium ion, zinc ion, nitrogen ion, magnesium ion, ammonium ion, and silver ion, and more preferably one or more cations selected from the group consisting of sodium ion, zinc ion, nitrogen ion, magnesium ion, potassium ion, and ammonium ion.

[0032] In the strand according to this embodiment, the zeolite (C) content may be 0.1 to 3.0% by weight relative to 100% by weight of the strand according to this embodiment, but it is preferably 0.2 to 2.0% by weight, as this results in a mesh structure with particularly excellent moldability and strength. Here, if the zeolite (C) content in the mesh structure of this embodiment is less than 0.1% by weight, the odor improvement effect will be insufficient, and if it is more than 3.0% by weight, the moldability for obtaining the mesh structure will deteriorate, which is undesirable.

[0033] In the strand according to this embodiment, examples of antioxidants (D) include known phenolic antioxidants, phosphite antioxidants, thioether antioxidants, phosphorus antioxidants, hybrid antioxidants that are both phenolic and phosphorus (hereinafter also simply referred to as "hybrid antioxidants"), NH-type hindered amine light stabilizers, N-CH3-type hindered amine light stabilizers, and the like. Among these, phosphorus antioxidants or hybrid antioxidants are preferred because they result in a mesh structure that can more effectively suppress odors caused by thermal degradation during molding. In the mesh structure of this embodiment, at least one type of antioxidant (D) is included, and two or more types may be included.

[0034] Examples of phenolic antioxidants include 1,3,5-tris[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4'-butylidenebis(6-tert-butyl-m-cresol), 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate stearyl, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], Sumilizer AG 80, and 2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mesitylene.

[0035] Phosphate antioxidants include 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 2,4,8,10-tetrakis(1,1-dimethylethyl)-6-[(2-ethylhexyl)oxy]-12H-dibenzo[d,g][1,3,2]dioxaphosphosine, tris(2,4-di-tert-butylphenyl) phosphite, tris(4-nonylphenyl) phosphite, and 4,4'-Isopropylidenediphenol C12-15 alchohol Examples include phosphite, diphenyl(2-ethylhexyl) phosphite, diphenylisodecyl phosphite, triisodecyl phosphite, and triphenyl phosphite.

[0036] Examples of thioether-based antioxidants include bis[3-(dodecylthio)propionic acid]2,2-bis[[3-(dodecylthio)1-1oxopropyloxy]methyl]1,3-propanediyl and 3,3'-thiobispropionic acid ditridecyl.

[0037] An example of a hybrid antioxidant is SumiLizer GP.

[0038] To prevent degradation due to heat, it is preferable to include both a phenolic antioxidant and a phosphite-based antioxidant as the antioxidant (D).

[0039] In the strand according to this embodiment, the content of antioxidant (D) may be 0.01 to 0.5% by weight relative to 100% by weight of the strand according to this embodiment, but is preferably 0.1 to 0.5% by weight. Here, if the content of antioxidant (D) is less than 0.01% by weight, there is a concern that the formability will deteriorate, and if it is more than 0.5% by weight, gas will be generated during molding, which is undesirable.

[0040] The strand according to this embodiment may consist only of the thermoplastic elastomer (A) described above, a polyethylene resin (B) derived from the recovered material of the mesh structure, a zeolite (C), and an antioxidant (D), but may also contain other components. Examples of such components include lubricants and functional agents, in addition to other components derived from the recovered material of the mesh structure described above. The strand according to this embodiment may contain one or more of these components.

[0041] Examples of lubricants include hydrocarbon waxes, higher alcohol-based waxes, amide waxes, ester waxes, and metal soaps. When the strand according to this embodiment contains a lubricant, the lubricant content is preferably more than 0% by weight and 0.1% by weight or less, based on 100% by weight of the strand according to this embodiment.

[0042] Examples of functional additives include deodorants, antibacterial agents, antifungal agents, colorants, fragrances, flame retardants, moisture absorbers, moisture release agents, and the like. When a functional additive is contained in the strand according to this embodiment, the content of the functional additive is preferably more than 0.01% by weight and 2.0% by weight or less, based on 100% by weight of the strand according to this embodiment.

[0043] The strand according to this embodiment may be a composite linear structure in combination with other thermoplastic resins, provided that the thermoplastic elastomer (A) content is 49 to 99% by weight, the polyethylene resin (B) derived from recovered material of the mesh structure content is 0.89 to 50% by weight, the zeolite (C) content is 0.1 to 3.0% by weight, and the antioxidant (D) content is 0.01 to 0.5% by weight, as long as the effects of the present invention are not impaired. Examples of composite structures include composite linear structures such as sheath-core type, side-by-side type, and eccentric sheath-core type, where the linear body itself is composited.

[0044] In this embodiment, the fiber diameter of the strand is preferably 0.1 mm to 3.0 mm, and more preferably 0.5 mm to 3.0 mm, from the viewpoint of maintaining hardness when used as a cushioning material. The fiber diameter of the strand can be determined by measuring the diameter (or the maximum diameter if the cross-section is not a perfect circle) at any one point on each of 50 arbitrarily selected strands and averaging these measurements.

[0045] In this embodiment, the mesh structure is preferably a three-dimensional loop-jointed structure in which loop-shaped strands arranged in a three-dimensional positional relationship are joined to each other, from the viewpoint of maintaining hardness when used as a cushioning material. Examples of three-dimensional loop-jointed structures include a random loop structure in which strands are randomly arranged so that loops overlap (Figure 1(a)), and a honeycomb loop structure in which strands are arranged so that the outer circumferences of loops are in contact (Figure 1(b)). In these three-dimensional loop-jointed structures, the strands are joined to each other at the points where they come into contact. It should be noted that the random loop structure can also be described as a structure in which multiple strands are randomly intertwined in a spiral and partially joined.

[0046] A three-dimensional loop-jointed structure can be formed, for example, by extruding molten manufacturing material (a raw material mixture described later) downward in a strand-like manner from a die having multiple holes, bending the strand to form loops, and bringing each loop into contact with the others in a molten state. As a result, the contact points of the strands are welded together, forming a three-dimensional loop-jointed structure. A random loop structure can be formed by extruding molten material from a die such that the loop diameter of the strand is larger than the pitch of the multiple holes (nozzle pitch) formed in the die. On the other hand, a honeycomb loop structure can be formed by extruding molten manufacturing material from a die such that the loop diameter of the strand is approximately the same as the pitch of the multiple holes formed in the die. Honeycomb loop structures, random loop structures, and their manufacturing methods are also described in publicly available documents such as International Publication No. 2018 / 074075, and those described in publicly available documents may be used.

[0047] The thickness of the mesh structure in this embodiment is preferably 10 mm or more, and more preferably 20 mm or more, from the viewpoint of cushioning properties when used as a cushioning material. Furthermore, from the viewpoint of ease of manufacturing, the thickness of the mesh structure in this embodiment is preferably 300 mm or less, more preferably 200 mm or less, and even more preferably 150 mm or less.

[0048] The apparent density of the mesh structure in this embodiment is 0.005 g / cm³, from the viewpoint of maintaining the hardness required when used as a cushioning material. 3 More than 0.20g / cm 3 The following is preferable: 0.02 g / cm³ 3 More than 0.15g / cm 3 The following is more preferable: The apparent density of the mesh structure is the weight [g] of the mesh structure multiplied by the volume [cm³]. 3The volume can be calculated by dividing by ]. The volume of the mesh structure can be calculated by cutting the mesh structure into 30cm x 30cm (length x width) pieces, leaving them unloaded for 24 hours, and then measuring the average of the thickness at four arbitrary points using a thickness gauge (for example, the FD-80N model manufactured by Polymer Instruments Co., Ltd.). This average value is used as the height, and 30cm as the length and width. The weight of the mesh structure used to determine the apparent density can be measured by weighing the mesh structure cut into 30cm x 30cm (length x width) pieces using a measuring instrument (for example, an electronic balance).

[0049] In the mesh structure of this embodiment, the strand bonding strength is preferably 25N or higher, and more preferably 30N or higher, from the viewpoint of further improving durability (especially resistance to sagging) when used as a cushioning material. The upper limit of the strand bonding strength is not particularly limited, but for example, it can be 100N or lower. The strand bonding strength can be measured by a method in accordance with Method A (strip method) of JIS L 1096 (General Textile Testing Methods). The test speed can be 200 mm / min, and the initial test length (distance between chucks of the tensile testing machine) can be 200 mm.

[0050] The mesh structure of this embodiment is particularly suitable as a cushioning material among the mesh structures described above. It is a three-dimensional loop-jointed structure in which loop-shaped filaments with a fiber diameter of 0.1 mm to 3.0 mm are joined together, and has an apparent density of 0.005 g / cm³. 3 More than 0.20g / cm 3 Preferably, the mesh structure is such that the following conditions are met, and the strand bonding strength is 25N or higher. When used as a cushioning material, a mesh structure having these characteristics can maintain the necessary hardness for cushioning, and its durability (especially resistance to sagging) is further improved.

[0051] The mesh structure of this embodiment may be multilayered, as long as it does not impair the effects of the present invention. Examples of multilayered structures include structures in which the surface layer and back layer are composed of strands of different fineness, or structures in which the surface layer and back layer are composed of structures with different apparent densities. Methods for multilayering include changing the diameter of the nozzle orifice hole, stacking mesh structures and fixing them with geodesy, melting and fixing them by heating, bonding them with adhesive, and restraining them with sewing or bands.

[0052] The mesh structure of this embodiment may be subjected to functional treatments such as deodorizing, antibacterial, antifungal, coloring, directionality, flame retardancy, and moisture absorption / release, to the extent that it does not impair the effects of the present invention. The functional treatment may be one type of treatment or two or more types of treatments. Furthermore, the functional treatment can be performed at any stage from the manufacture of the mesh structure to the use of the mesh structure. As a method of functional treatment, known methods such as adding a functional agent to the raw material (raw material mixture described later) can be used.

[0053] The mesh structure of this embodiment can be used, for example, as a mesh structure for seats or chairs for automobiles or railways, beds, sofas, mattresses, or pillows. For use in these applications, the mesh structure of this embodiment may be further molded or processed into a predetermined shape.

[0054] Next, the method for manufacturing the mesh structure of this embodiment (hereinafter also referred to as "the manufacturing method of this embodiment") will be described.

[0055] The manufacturing method of this embodiment includes a step of forming strands from a molten mixture (hereinafter also simply referred to as "molten mixture") containing 49 to 99% by weight of a thermoplastic elastomer (A), 0.89 to 50% by weight of a polyethylene resin (B) derived from recovered mesh structures, 0.1 to 3.0% by weight of a zeolite (C), and 0.01 to 0.5% by weight of an antioxidant (D), and bringing the strands into contact with each other in a molten state.

[0056] The method for obtaining the molten mixture is not particularly limited, but a process of melting and mixing thermoplastic elastomer (A), recovered material from the mesh structure, zeolite (C), and antioxidant (D) (hereinafter also simply referred to as "melt mixing process") can be used, such that the content of thermoplastic elastomer (A) is 49 to 99% by weight, the content of polyethylene resin (B) derived from recovered material of the mesh structure is 0.89 to 50% by weight, the content of zeolite (C) is 0.1 to 3.0% by weight, and the content of antioxidant (D) is 0.01 to 0.5% by weight.

[0057] The melt mixing treatment can be carried out at a temperature at which at least one of the following components melts: thermoplastic elastomer (A), recovered network structure, zeolite (C), and antioxidant (D) (i.e., above the melting point of the component with the lowest melting point). It is not necessary to carry out the treatment at a temperature at which all components melt, but from the viewpoint of suppressing the uneven distribution of each component, it is preferable to carry out the treatment at a temperature at which all components except zeolite (C) melt. The treatment temperature for the melt mixing treatment can be, for example, 160°C to 260°C, and preferably 180°C to 240°C.

[0058] The melt mixing process only requires that each component be mixed without uneven distribution, and the means are not limited; for example, known kneading equipment can be used. Examples of kneading equipment that can be used for the melt mixing process include single-screw extruders, twin-screw extruders, multi-screw extruders, Banbury mixers, pressure kneaders, rotary rolls, and internal mixers.

[0059] In the melt mixing process, if the amount of thermoplastic elastomer (A) is 49-99% by weight, the amount of polyethylene resin (B) derived from the recovered mesh structure is 0.89-50% by weight, the amount of zeolite (C) is 0.1-3.0% by weight, and the amount of antioxidant (D) is 0.01-0.5% by weight per 100g by weight of the molten mixture, then other components (for example, lubricants and functional additives) may be added and melt-mixed together with the thermoplastic elastomer (A), the recovered mesh structure, the zeolite (C), and the antioxidant (D).

[0060] In addition, while the recovered mesh structure material used in the melt-mixing process may be the mesh structure material itself, it is preferable to use the recovered mesh structure material that has undergone pretreatment such as washing or crushing. Washing is a process of washing the recovered mesh structure material, and by performing this process, the amount of adhering material to the recovered material can be reduced. Conventional washing methods can be used for the washing process, and a washing method can be appropriately selected depending on the adhering material to the recovered material. Crushing is a process of crushing the recovered material, and by performing this process, the recovered material is less likely to be unevenly distributed in the molten mixture. Conventional crushing methods can be used for the crushing process, and a crushing method can be appropriately selected depending on the composition and physical properties of the recovered material.

[0061] In the manufacturing method of this embodiment, strands are formed from a molten mixture, and the strands are brought into contact with each other in a molten state. The strands to be formed from the molten mixture may be obtained by forming the molten mixture obtained from the molten mixture treatment as is, or they may be obtained by cooling and solidifying the molten mixture obtained from the molten mixture treatment, then reheating and remelting it before forming. The reheating temperature of the solidified molten mixture is preferably 200°C to 280°C, and more preferably 220°C to 270°C, in order to facilitate the formation of a mesh structure in the strands to be formed and to maintain the durability (e.g., strength) of the fused strands.

[0062] To form strands from a molten mixture, for example, a method can be used in which the molten mixture is extruded from a die or nozzle having multiple orifices. Alternatively, to bring the formed strands into contact while they are still molten, a method can be used in which the strands are brought into contact with each other before they solidify. By bringing the formed strands into contact while they are still molten, the contact points of the strands are welded together, resulting in a mesh structure. The strands that have been brought into contact while molten can be cooled to the temperature at which the strands solidify.

[0063] Furthermore, a method for forming strands from a molten mixture and bringing the strands into contact with each other in a molten state is described, for example, in International Publication No. 2012 / 035736, and the method described in International Publication No. 2012 / 035736 may be used. That is, the molten mixture is discharged from a multi-row nozzle having multiple holes (orifices) to form strands, and the strands are brought into contact with each other in a molten state to fuse them together. The three-dimensional mesh structure formed by the fusion of the strands is drawn into cooling water by a take-up conveyor and cooled. The three-dimensional mesh structure is pulled out of the cooling water, and after draining or drying, a mesh structure with smoothed surfaces on both sides can be obtained. To obtain a mesh structure with only one side smoothed, the molten mixture is discharged onto a take-up conveyor net with an inclination, and the strands are brought into contact with each other in a molten state to fuse them together, forming a three-dimensional mesh structure while cooling while relaxing the shape of only the take-up net surface.

[0064] Here, it is preferable to heat-treat the strands that have been brought into contact in a molten state at a temperature at least 20°C lower than the melting point of the thermoplastic elastomer (A) after the strands have solidified (hereinafter also referred to as "annealing treatment"). Annealing treatment improves durability (especially resistance to sagging) compared to cases where annealing treatment is not performed. This suppresses deformation due to heat, etc. In particular, when ethylene-1-hexene copolymer, which is a copolymer of ethylene and 1-hexene, is used as the thermoplastic elastomer (A), durability (especially resistance to sagging) is further improved by annealing treatment compared to cases where other thermoplastic elastomers are used. The treatment temperature for annealing treatment should be at least 20°C lower than the melting point of the thermoplastic elastomer (A), but it is preferable that the temperature does not fall more than 60°C lower than the melting point of the thermoplastic elastomer (A). For example, a specific temperature for annealing treatment is 30 to 75°C.

[0065] The mesh structure of this embodiment described above can suppress unpleasant odors and has excellent moldability and durability. Unpleasant odors that can be suppressed by the mesh structure of this embodiment include, for example, odors caused by impurities adhering to the recovered mesh structure used as a manufacturing raw material, and odors caused by impurities adhering as a result of using the mesh structure of this embodiment. Examples of odor-causing substances include one or more substances selected from the group consisting of sulfur compounds, organic solvents, aldehydes, and lower fatty acids. Lower fatty acids refer to organic fatty acids with 10 or fewer carbon atoms. [Examples]

[0066] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0067] The characteristics of the examples were evaluated using the following method.

[0068] (1) Odor measurement 50g of the mesh structures described in the examples and comparative examples below were placed in a 300cc airtight glass container and left to stand at 40°C for 2 hours. Afterward, the odor inside the glass container was evaluated by three panelists. The evaluation criteria were: ○ for almost no odor, △ for slight odor, and × for noticeable odor. Panelists with extreme preferences or allergies were excluded, and a common understanding was established that an × (odor detected) rating indicated an odor nearly identical to that of the recovered mesh structures used as raw materials in the examples and comparative examples below. The unpleasant odor components generated from the recovered mesh structures were n-butyraldehyde, isovaleraldehyde, n-butyric acid, and n-valeric acid. Therefore, if no unpleasant odor is detected, it can be concluded that odors containing aldehydes and organic acids can be suppressed.

[0069] (2) Density of thermoplastic elastomer Using a hooded MI meter, the sample was extruded at 190°C and under a load of 21.2N, and then slowly cooled in the hood for 5 minutes. Afterward, the density was measured using the density gradient tube method in accordance with JIS K6760 (1995). The temperature of the density gradient tube was set to 23°C.

[0070] (3) Melt Flow Rate (MFR) Measurements were taken in accordance with JIS K7210, at a temperature of 190°C and a load of 21.2N.

[0071] (4)Join strength Five measurements were taken using Method A (strip method) of JIS L 1096 (General Textile Testing Methods), and the average value was used as the joint strength. The test speed was 200 mm / min, and the initial test length (distance between chucks on the tensile testing machine) was 200 mm.

[0072] (5) Hardness retention rate The mesh structures of the examples and comparative examples described later were cut to a size of 30 cm x 30 cm and heat-treated in an oven heated to 60°C for 10 minutes. After measuring the thickness (hereinafter also referred to as "pre-treatment thickness") using calipers, the structure was compressed at a speed of 10 mm / min to reduce its thickness, and the compression load [N] when the thickness was reduced by 25% of the pre-treatment thickness was defined as the pre-treatment load (c). Subsequently, using a Shimadzu servo pulser, compression and recovery were repeated 80,000 times at a cycle of 1 Hz in an environment of 20°C ± 2°C. The compression was performed to reduce the thickness to 50% of the pre-treatment thickness. After standing for 30 minutes, the thickness (hereinafter also referred to as "post-treatment thickness") was measured using calipers, and the structure was compressed at a speed of 10 mm / min to reduce its thickness, and the compression load [N] when the thickness was reduced by 25% of the post-treatment thickness was defined as the post-treatment load (d). The load retention rate [%] at 25% compression after 50% displacement and repeated compression was calculated using formula (d) / (c) × 100. The load retention rate at 25% compression after 50% displacement and repeated compression was determined for three different locations on the mesh structure, and the average value was taken as the hardness retention rate. A hardness retention rate exceeding 50% was marked with ○, and a rate of 50% or less was marked with ×.

[0073] (6) Apparent density The mesh structures of the examples and comparative examples described later were cut to a size of 30 cm x 30 cm, left unloaded for 24 hours, and then the height at four points was measured using an FD-80N thickness gauge manufactured by Polymer Instruments Co., Ltd. The average of the measured heights was taken as the height of the sample, and the volume of the sample was calculated using 30 cm as the length and width of the sample. The weight of the sample was measured by placing the sample on an electronic balance. The volume and weight of the sample were measured three times, and the average values ​​were calculated. The apparent density was calculated by dividing the average weight of the sample by the average volume.

[0074] (7) Molding processability The condition of the strands extruded from the die at a predetermined temperature was determined according to the following criteria. "○": The strand forms a loop and does not hang down. "×": The strand hangs down and does not form a loop.

[0075] (8) Melting point, number of endothermic peaks Using a differential scanning calorimeter (DSC7000X, Hitachi High-Tech Science Co., Ltd.), a 5 mg sample of the mesh structure was weighed and measured at a heating rate of 10°C / min to obtain a melting curve (endothermic curve), and the temperature of the endothermic peak (melting peak) was determined.

[0076] [Example 1] Thermoplastic elastomer (A) has a density of 905 kg / m³. 3 88.85% by weight of ethylene-1-hexene copolymer (product name Nipolon-Z 15P51B, manufactured by Tosoh Corporation) with an MFR of 4.0 g / 10 min, 10% by weight of polyethylene mesh structure recovery material obtained by crushing mesh structures recovered from customers with a rotary cutter as a raw material for polyethylene resin (B) derived from recovered mesh structures, and zeolite (C) with a particle size of 1-3 μm, a cation species of sodium, and a BET specific surface area of ​​408 m². 2 This product contains 0.8% by weight of MFI-type zeolite (C1) (product name Dashlite 3MH, manufactured by Sinanen Zeomic Co., Ltd.) at a concentration of / g, with an average particle size of 1.5 μm, a zinc cation species, and a BET specific surface area of ​​520 m². 2The mixture contained 0.2% by weight of FAU-type zeolite (C2) (product name Dashlite ZH10D, manufactured by Sinanen Zeomic Co., Ltd.) at a concentration of / g, and 0.15% by weight of Sumirizer GP, manufactured by Sumitomo Chemical Co., Ltd., as an antioxidant (D). The recovered polyethylene mesh structure contained 99.9% by weight of linear low-density polyethylene per 100% by weight of the recovered material.

[0077] The prepared raw materials were pre-mixed in a tumbler, and then melt-mixed using a twin-screw extruder (TEX25αIII, manufactured by Japan Steel Works Ltd.) at a screw rotation speed of 156 rpm and a barrel temperature of 210°C to obtain a pelletized composition.

[0078] The obtained composition was melted to a resin temperature of 260°C. The molten composition was extruded from a die into strands with a fiber diameter of 0.9 mm, according to a known method described in International Publication No. 2012 / 035736, etc., and the extruded strands were dropped into a chute inclined at a 40-degree angle to the vertical. The strands sliding down the chute were collected by a take-up conveyor installed in cooling water, and the strands were then immersed in the cooling water. During the process from when the strands fell into the chute until they were immersed in the cooling water, the strands came into contact with each other in a molten state, forming a three-dimensional loop-jointed structure (honeycomb loop structure). After removing the three-dimensional loop-jointed structure from the cooling water, it underwent annealing in an oven at an ambient temperature of 50°C, and was further conditioned at room temperature for 24 hours or more to obtain the mesh structure of this embodiment.

[0079] The resulting mesh structure had a hardness retention rate of 67%, a bonding strength of 41 N, and an apparent density of 0.06 g / cm³. 3 The odor measurement results were positive, and the moldability evaluation was also positive.

[0080] [Example 2] The mesh structure of this example was obtained in the same manner as in Example 1, except that the content of thermoplastic elastomer (A) was changed to 49.85% by weight, and the content of polyethylene resin (B) raw material derived from the recovered mesh structure was changed to 49% by weight.

[0081] The resulting mesh structure had a hardness retention rate of 72%, a bonding strength of 30 N, and an apparent density of 0.06 g / cm³. 3 The odor measurement results were positive, and the moldability evaluation was also positive.

[0082] [Example 3] In Example 1, a mesh structure was obtained using the same method as in Example 1, except that MFI-type zeolite (C1) was not used and the content of thermoplastic elastomer (A) was changed to 89.65% by weight.

[0083] The resulting mesh structure had a hardness retention rate of 72%, a bonding strength of 36 N, and an apparent density of 0.07 g / cm³. 3 The odor measurement results were positive, and the moldability evaluation was also positive.

[0084] [Comparative Example 1] The mesh structure of this comparative example was molded in the same manner as in Example 1, except that the content of thermoplastic elastomer (A) was changed to 10% by weight and the recovered mesh structure was 88.85% by weight.

[0085] The resulting mesh structure had a hardness retention rate of 65%, a bonding strength of 39 N, and an apparent density of 0.06 g / cm³. 3 However, the odor measurement results were negative.

[0086] [Comparative Example 2] The network structure of this comparative example was obtained using the same method as in Example 1, except that MFI-type zeolite (C1) and FAU-type zeolite (C2) were not used, and the content of thermoplastic elastomer (A) was changed to 89.85% by weight.

[0087] The resulting mesh structure had a hardness retention rate of 67%, a bonding strength of 41 N, and an apparent density of 0.06 g / cm³. 3 However, the odor measurement results were negative.

[0088] [Comparative Example 3] In Example 1, an attempt was made to manufacture a mesh structure using the same method as in Example 1, except that the content of thermoplastic elastomer (A) was changed to 69.85% by weight, the content of MFI-type zeolite (C1) was changed to 16% by weight, and the content of FAU-type zeolite (C2) was changed to 4% by weight. However, the extrusion torque became too high, and the mixture of each raw material that had been pre-mixed in a tumbler could not be extruded from the twin-screw extruder. As a result, pellet-shaped raw material mixture could not be obtained, and the mesh structure could not be manufactured.

[0089] Table 1 below shows the results of the characterization evaluation of the mesh structures of the examples and comparative examples. [Table 1] [Industrial applicability]

[0090] The mesh structure of this embodiment uses recycled materials (recovered mesh structures) as its raw material, thus enabling the creation of a product with reduced environmental impact. Furthermore, this embodiment can suppress unpleasant odors and provide a mesh structure with excellent moldability and durability. The mesh structure of this embodiment is useful as a mesh structure for use in office chairs, furniture, sofas, bedding such as beds, and seats for vehicles such as trains, automobiles, and motorcycles, while reducing environmental impact.

Claims

1. A mesh structure composed of multiple strands, The strand is characterized by comprising 49 to 99% by weight of a thermoplastic elastomer (A), 0.89 to 50% by weight of a polyethylene resin (B) derived from recovered material of a mesh structure, 0.1 to 3.0% by weight of a zeolite (C), and 0.01 to 0.5% by weight of an antioxidant (D).

2. The aforementioned mesh structure is a three-dimensional loop-jointed structure in which loop-shaped strands having a fiber diameter of 0.1 mm or more and 3.0 mm or less are joined together. The apparent density of the aforementioned mesh structure is 0.005 g / cm³. ３ 0.20g / cm or more ３ The following: The mesh structure according to claim 1, characterized in that the bonding strength between the strands is 25 N or more.

3. The thermoplastic elastomer (A) has a density of 940 kg / m³. ３ The network structure according to claim 1, characterized in that it is an ethylene-α-olefin copolymer.

4. The density of the ethylene-α-olefin copolymer is 915 kg / m³. ３ The following: The mesh structure according to claim 3, characterized in that, in the melting curve of the mesh structure measured using a differential scanning calorimeter, there is one endothermic peak in the range of 80°C to 110°C, and two or more endothermic peaks in the range of less than 80°C.

5. The mesh structure according to claim 1, wherein the zeolite (C) is two or more types of zeolites.

6. The network structure according to claim 1, wherein the antioxidant (D) is a phosphorus-based antioxidant.

7. A method for manufacturing a mesh structure, comprising the steps of forming strands from a molten mixture containing 49 to 99% by weight of a thermoplastic elastomer (A), 0.89 to 50% by weight of a polyethylene resin (B) derived from recovered mesh structures, 0.1 to 3.0% by weight of a zeolite (C), and 0.01 to 0.5% by weight of an antioxidant (D), and bringing the strands into contact with each other in a molten state.

Images