Network structure

Abstract

The net-shaped structure body has a three-dimensional random loop joined structure comprising continuous thermoplastic elastomer filaments of 0.1 to 3.0 mm fiber diameter, the continuous thermoplastic elastomer filaments having been structured as a composite from a polyester-based thermoplastic elastomer and a polystyrene-based thermoplastic elastomer. The net-shaped structure body has a 70°C compressive residual stress of 35% or lower, and a rebound resilience of 10% or lower. In this manner, a net-shaped structure body is provided, which is highly vibration absorbent and is excellent in terms of thermal resistance and resistance to loosening.

Description

Mesh structure

[0001] This invention relates to a mesh structure that exhibits high vibration absorption and excellent heat resistance and deformation resistance, and is suitable for use as a cushioning material in vehicle seats, bedding, and the like, taking advantage of these properties.

[0002] Patent Document 1 (Japanese Patent Application Publication No. 2013-76200) describes a mesh structure consisting of a continuous linear body composite structure made of a resin composition containing a polyester-based thermoplastic elastomer and a resin composition containing a polystyrene-based thermoplastic elastomer. However, this mesh structure has not been able to obtain a mesh structure that achieves both vibration absorption and heat resistance and deformation resistance.

[0003] Japanese Patent Publication No. 2013-76200

[0004] The present invention aims to provide a mesh structure that exhibits high vibration absorption and excellent heat resistance and deformation resistance.

[0005] As a result of diligent research, the inventors discovered that by creating a composite structure using a specific thermoplastic elastomer from continuous linear bodies constituting a three-dimensional random loop joint structure, a mesh structure with high vibration absorption and excellent heat resistance and deformation resistance can be obtained, leading to the present invention.

[0006] In other words, the present invention comprises the following configurations: [1] A mesh structure having a three-dimensional random loop joint structure made of continuous linear thermoplastic elastomers with a fiber diameter of 0.1 mm or more and 3.0 mm or less, wherein the continuous linear thermoplastic elastomers are composite structures of thermoplastic elastomers including polyester-based thermoplastic elastomers and polystyrene-based thermoplastic elastomers, and the mesh structure has a compression residual set of 35% or less at 70°C and a rebound modulus of 10% or less. [2] The mesh structure according to [1], wherein the rebound modulus of the polyester-based thermoplastic elastomer is 75% or more. [3] The mesh structure according to [1], wherein the Shore D hardness of the polyester-based thermoplastic elastomer is 40 or less. [4] The mesh structure according to any one of [1] to [3], wherein the melting point of the polyester-based thermoplastic elastomer is less than 200°C. [5] A mesh structure according to any one of [1] to [4] above, comprising a composite structure of a continuous linear thermoplastic elastomer having a volume ratio of 90 / 10 to 10 / 90 between the polyester thermoplastic elastomer and the polystyrene thermoplastic elastomer. [6] A mesh structure according to any one of [1] to [5] above, wherein the composite structure of the continuous linear thermoplastic elastomer is either a sheath-core structure or a side-by-side structure. [7] A mesh structure according to any one of [1] to [6] above, wherein the polyester thermoplastic elastomer is at least one of polyester ether block copolymer and polyester ester block copolymer. [8] A mesh structure according to any one of [1] to [7] above, wherein the polystyrene thermoplastic elastomer is at least one selected from the group consisting of styrene-butadiene copolymer, styrene-isoprene copolymer, and hydrogenated copolymers thereof. [9] A mesh structure according to any one of [1] to [8] above, wherein the continuous linear thermoplastic elastomer has a hollow cross-section.

[10] The mesh structure according to any one of [1] to [9] above, wherein the thermoplastic elastomer continuous linear body has an irregular cross-section.

[0007] This invention relates to a mesh structure that exhibits high vibration absorption and excellent heat resistance and deformation resistance, and can be suitably used in vehicle seats, bedding, and the like, taking advantage of these properties.

[0008] The mesh structure of the present invention is formed by bending continuous linear bodies (sometimes referred to as "continuous linear bodies" in this specification) made of thermoplastic elastomer with a fiber diameter of 0.1 mm to 3.0 mm, bringing the continuous linear bodies into contact with each other, and fusing the contact points to form a three-dimensional random loop joint structure. As a result, even when subjected to very large stresses and large deformations, the entire mesh structure, consisting of the fused and integrated three-dimensional random loop joint structure, deforms to absorb the stress. When the stress is released, the rubber elasticity of the thermoplastic elastomer is activated, and the mesh structure can recover to its original form. If the fiber diameter of the continuous linear bodies is less than 0.1 mm, the compressive strength is low, resulting in a decrease in rebound force. On the other hand, if the fiber diameter of the continuous linear bodies exceeds 3.0 mm, the individual compressive strength of the continuous linear bodies is high, but the number of continuous linear bodies constituting the mesh structure decreases, resulting in poor force distribution. In particular, at 100 kg / cm²... ２ When subjected to the above-mentioned extremely large compressive forces, stress concentration can cause deformation (compression set), which may limit the applications for use. The fiber diameter is preferably 0.3 mm to 2.0 mm, and more preferably 0.4 mm to 1.5 mm. In addition, in this invention, not only continuous linear bodies with a single fiber diameter but also continuous linear bodies with different fiber diameters can be used, and an optimal configuration can be achieved by combining them with the apparent density.

[0009] The continuous linear members constituting the mesh structure of the present invention are composite structures of thermoplastic elastomers including polyester-based thermoplastic elastomers and polystyrene-based thermoplastic elastomers. Preferably, the polyester-based thermoplastic elastomer has a rebound modulus of 75% or higher or a Shore D hardness of 40 or lower. Typically, the continuous linear members constituting the mesh structure are composited to improve the vibration absorption and heat resistance and sag resistance of the mesh structure. In this case, to improve vibration absorption, a polystyrene-based thermoplastic elastomer with a rebound modulus of 5% or lower is used. Furthermore, to improve heat resistance and sag resistance, (a) a polyethylene-based thermoplastic elastomer with a high melting point and low rebound modulus, or (b) a polyethylene-based thermoplastic elastomer with a high melting point, low rebound modulus, and low Shore D hardness is used. These two are then composited in an appropriate volume ratio. However, the present inventors have discovered that using a polyester thermoplastic elastomer with a rebound modulus of 75% or higher, or a Shore D hardness of 40 or lower, and a relatively low melting point, improves both vibration absorption and heat resistance and fatigue resistance, leading to the present invention. The melting point of the polyester thermoplastic elastomer is preferably less than 200°C, more preferably 195°C or lower, and particularly preferably 190°C or lower. Furthermore, from the viewpoint of heat resistance and fatigue resistance, the melting point is preferably 150°C or higher, more preferably 155°C or higher, and particularly preferably 160°C or higher.

[0010] Examples of polyester-based thermoplastic elastomers used in the present invention include polyester ether block copolymers in which thermoplastic polyester is used as the hard segment and polyalkylenediol as the soft segment, or polyester ester block copolymers in which aliphatic polyester is used as the soft segment. More specifically, the composition of the polyester ether block copolymer includes at least one dicarboxylic acid selected from aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, and diphenyl-4,4'-dicarboxylic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, aliphatic dicarboxylic acids such as succinic acid, adipic acid, and sebatic acid dimer acid, or ester-forming derivatives thereof, and 1,4-butanediol, ethylene glycol, trimethylene glycol, tetramethylene glycoside This is a ternary block copolymer composed of at least one diol component selected from aliphatic diols such as ethanol, pentamethylene glycol, and hexamethylene glycol, alicyclic diols such as 1,1-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, or ester-forming derivatives thereof, and at least one polyalkylenediol selected from polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or ethylene oxide-propylene oxide copolymers having an average molecular weight of about 300 to 5000. An example of a polyester ester block copolymer is a ternary block copolymer composed of the above-mentioned dicarboxylic acid and diol and at least one polyester diol such as polylactone having an average molecular weight of about 300 to 5000. Considering thermal adhesion, hydrolysis resistance, elasticity, heat resistance, etc., the preferred materials are (1) a ternary block copolymer consisting of terephthalic acid and / or isophthalic acid as the dicarboxylic acid, 1,4-butanediol as the diol component, and polytetramethylene glycol as the polyalkylenediol, and (2) a ternary block copolymer consisting of terephthalic acid and / or naphthalene-2,6-dicarboxylic acid as the dicarboxylic acid, 1,4-butanediol as the diol component, and polylactone as the polyester diol.Particularly preferred is a ternary block copolymer comprising (1) terephthalic acid and / or isophthalic acid as the dicarboxylic acid, 1,4-butanediol as the diol component, and polytetramethylene glycol as the polyalkylenediol. In special cases, a polysiloxane-based soft segment can also be introduced.

[0011] The polyester thermoplastic elastomer used in this invention is not particularly limited, but from the viewpoint of exhibiting high vibration absorption while appropriately maintaining the heat resistance and fatigue resistance of the mesh structure, it is preferable to use a polyester thermoplastic elastomer with a rebound modulus of 75% or more or a Shore D hardness of 40 or less. When the rebound modulus of the polyester thermoplastic elastomer is 75% or more, the impact received by the polyester thermoplastic elastomer is more easily transmitted to the polystyrene thermoplastic elastomer that together constitutes the composite structured continuous linear body. As a result, the vibration absorption exhibited by the polystyrene thermoplastic elastomer is increased. The rebound modulus of the polyester thermoplastic elastomer is more preferably 78% or more, and even more preferably 80% or more. Furthermore, when the Shore D hardness is 40 or less, the polyester thermoplastic elastomer is not too hard, making it easier to fully utilize the shock absorption properties of the polystyrene thermoplastic elastomer. The Shore D hardness of the polyester thermoplastic elastomer is preferably 38 or less, more preferably 36 or less, and even more preferably 34 or less.

[0012] The polystyrene-based thermoplastic elastomer used in the present invention is not particularly limited, but a rebound modulus of 10% or less is preferred from the viewpoint of improving the vibration absorption of the mesh structure. When the rebound modulus of the polystyrene-based thermoplastic elastomer is 10% or less, sufficient vibration damping is achieved, and the vibration absorption of the mesh structure is improved. The rebound modulus of the polystyrene-based thermoplastic elastomer is more preferably 7% or less, and even more preferably 5% or less. Examples of polystyrene-based thermoplastic elastomers that satisfy a rebound modulus of 10% or less include styrene-butadiene copolymers, styrene-isoprene copolymers, or hydrogenated versions thereof.

[0013] Furthermore, within the range that maintains the high vibration absorption and excellent heat resistance and fatigue resistance that are the objectives of the present invention, it is also possible to create a composite structure using a third thermoplastic elastomer other than polyester-based thermoplastic elastomers and polystyrene-based thermoplastic elastomers. Examples of the third thermoplastic elastomer include polyolefin-based thermoplastic elastomers.

[0014] The composition ratio of polyester-based thermoplastic elastomer to polystyrene-based thermoplastic elastomer in the composite continuous linear body constituting the mesh structure of the present invention is not particularly defined, but preferably the volume ratio of polyester-based thermoplastic elastomer to polystyrene-based thermoplastic elastomer is preferably 95 / 5 to 5 / 95, more preferably 92 / 8 to 8 / 92, and even more preferably 90 / 10 to 10 / 90. When the volume ratio is 100 / 0 to 95 / 5 (excluding 95 / 5), it becomes difficult to maintain high vibration absorption. On the other hand, when the volume ratio is 5 / 95 to 0 / 100 (excluding 5 / 95), it becomes difficult to maintain high heat resistance.

[0015] The mesh structure of the present invention has a rebound modulus of 10% or less, as measured using a rebound modulus measuring device. If the rebound modulus exceeds 10%, the vibration absorption of the mesh structure becomes insufficient. Preferably, it is 7% or less, more preferably 5% or less.

[0016] In the present invention, the 70°C compressive set of the mesh structure is an indicator for evaluating its heat resistance and sag resistance. The mesh structure of the present invention has a 70°C compressive set of 35% or less, preferably 30% or less, more preferably 25% or less, even more preferably 23% or less, particularly preferably 20% or less, and most preferably 18% or less. If the 70°C compressive set exceeds 35%, the required heat resistance and sag resistance may be insufficient. There is no specific lower limit for the 70°C compressive set, but in the mesh structure obtained in the present invention, it is 1% or more.

[0017] The mesh structure of the present invention preferably has a hardness of 2.0 kg / φ200 mm or more at 25% compression. The hardness at 25% compression is the stress at 25% compression in the stress-strain curve obtained by compressing the mesh structure to 75% using a circular compression plate with a diameter of φ200 mm. If the hardness at 25% compression is less than 2.0 kg / φ200 mm, the cushioning properties will be impaired. More preferably it is 2.5 kg / φ200 mm or more, and even more preferably 3.0 kg / φ200 mm or more. There is no particular upper limit, but preferably it is 30 kg / φ200 mm or less, more preferably 25 kg / φ200 mm or less, and even more preferably 20 kg / φ200 mm or less. If it is 30 kg / φ200 mm or more, the mesh structure becomes too hard, which is undesirable from the viewpoint of cushioning properties.

[0018] Various additives can be added to the continuous linear bodies constituting the network structure of the present invention, depending on the purpose. Possible additives include phthalate ester, trimellitic acid ester, fatty acid, epoxy, adipic acid ester, and polyester plasticizers; known hindered phenol, sulfur, phosphorus, and amine antioxidants; light stabilizers such as hindered amine, triazole, benzophenone, benzoate, nickel, and salicyl; antistatic agents; molecular modifiers such as peroxides; compounds having reactive groups such as epoxy compounds, isocyanate compounds, and carbodiimide compounds; metal deactivators; organic and inorganic nucleating agents, neutralizing agents, antacids, antibacterial agents, fluorescent whitening agents, fillers, flame retardants, flame retardant aids, and organic and inorganic pigments.

[0019] The continuous linear members constituting the mesh structure of the present invention preferably have an endothermic peak below the melting point in the melting curve measured by a differential scanning calorimeter. Those having an endothermic peak below the melting point exhibit significantly improved heat resistance and fatigue resistance compared to those without an endothermic peak. For example, as a preferred polyester thermoplastic elastomer of the present invention, when the acid component of the hard segment contains preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 100 mol%, of rigid terephthalic acid or naphthalene-2,6-dicarboxylic acid, and the glycol component is transesterified and polymerized to the required degree of polymerization, and then, as a polyalkylenediol, polytetramethylene glycol with an average molecular weight of preferably 500 to 5000, more preferably 1000 to 3000 is copolymerized at 10% to 70% by weight, and more preferably 20% to 60% by weight, the higher the content of rigid terephthalic acid or naphthalene-2,6-dicarboxylic acid in the acid component of the hard segment, the crystallinity of the hard segment is improved, making it less susceptible to plastic deformation and improving heat resistance and fatigue resistance. In addition, if annealing treatment is performed at a temperature at least 10°C lower than the melting point after fusion heat bonding, the heat resistance and fatigue resistance are further improved. Applying compressive strain before annealing further improves thermal fatigue resistance. Continuous linear mesh structures treated in this way exhibit a more pronounced endothermic peak in the melting curve measured by a differential scanning calorimeter (DSC) at temperatures above room temperature but below the melting point. Without annealing, no endothermic peak appears in the melting curve above room temperature but below the melting point. From this, it can be inferred that annealing rearranges the hard segments, forming pseudo-crystallization-like crosslinking points, thereby improving thermal fatigue resistance (hereinafter, this annealing process may be referred to as "pseudo-crystallization treatment").

[0020] The continuous linear bodies constituting the mesh structure of the present invention are characterized by being composite structures of polyester-based thermoplastic elastomer and polystyrene-based thermoplastic elastomer, but preferred composite structures include sheath-core structures and side-by-side structures. The sheath-core structure is also called a core-sheath type, and can be classified into concentric and eccentric types based on the positional relationship between the sheath and core, and into circular and irregular cross-sectional shapes, but any combination can be used in the present invention. The side-by-side structure is also called a parallel type, and has a cross-sectional structure in which multiple components are bonded together. In either the sheath-core structure or the side-by-side structure, the cross-sectional shape may be either hollow or solid.

[0021] When the composite structure of the continuous linear bodies constituting the mesh structure of the present invention is a sheath-core structure, the ratio of the sheath component to the core component is preferably 95 / 5 to 5 / 95 by volume, more preferably 92 / 8 to 8 / 92, and even more preferably 90 / 10 to 10 / 90. If the ratio is 100 / 0 to 95 / 5 (except 95 / 5) or 5 / 95 to 0 / 100 (except 5 / 95), the complementary physical properties of the polyester-based thermoplastic elastomer and the polystyrene-based thermoplastic elastomer become difficult to exhibit, making it difficult to achieve the objectives of the present invention, which are high heat resistance, high fatigue resistance, and high vibration absorption.

[0022] When the composite structure of the continuous linear bodies constituting the mesh structure of the present invention is a side-by-side structure, it is possible to have a structure in which the proportion of the surface of either the polyester-based plastic elastomer or the polystyrene-based thermoplastic elastomer of the linear bodies is increased (for example, a structure in which the sheath of an eccentric sheath-core structure is made of polyester-based plastic elastomer).

[0023] The present invention is characterized in that a continuous linear body has a composite structure. From the viewpoint of reducing the resilience modulus of the network structure, a continuous linear body in which 50% or more of the surface of the linear body is occupied by a polyester-based thermoplastic elastomer having a resilience modulus of 75% or more or a Shore D hardness of 40 or less is preferable. Among them, a continuous linear body in which 80% or more of the surface of the linear body is occupied by a polyester-based thermoplastic elastomer having a resilience modulus of 75% or more or a Shore D hardness of 40 or less is more preferable. A continuous linear body in which 100% of the surface of the linear body is occupied by a polyester-based thermoplastic elastomer having a resilience modulus of 75% or more or a Shore D hardness of 40 or less, that is, a continuous linear body having a sheath-core structure is particularly preferable.

[0024] The cross-sectional shape of the continuous linear body is not particularly limited, but by making it a hollow cross-section or a deformed cross-section, compressibility resistance and bulkiness can be imparted, which is particularly preferable when it is desired to reduce the fiber diameter. The compressibility resistance can be adjusted by the modulus of the material used. For a soft material, the hollowness ratio and the degree of deformation can be increased to adjust the gradient of the initial compression stress, and for a material with a slightly higher modulus, the hollowness ratio and the degree of deformation can be decreased to impart compressibility resistance with good sitting comfort. As another effect of the hollow cross-section and the deformed cross-section, by increasing the hollowness ratio and the degree of deformation, when the same compressibility resistance is imparted, it is possible to achieve more weight reduction.

[0025] A specific aspect of the network structure of the present invention is that the preferable range of the apparent density is 0.005 g / cm ３ or more and 0.20 g / cm ３ or less. If it is less than 0.005 g / cm ３ , the resilience is lost, so it is unsuitable as a cushioning material. If it exceeds 0.20 g / cm ３ , the resilience is too high and the sitting comfort deteriorates, which is not preferable. A more preferable apparent density of the present invention is 0.01 g / cm ３ or more and 0.10 g / cm ３ or less, and a further preferable range is 0.03 g / cm ３ or more and 0.06 g / cm ３The following describes how the mesh structure of the present invention can be given desirable properties by laminating multiple layers made of linear bodies with different fiber diameters and changing the apparent density of each layer. For example, if it consists of a surface layer with a thin fiber diameter and a base layer with a thick fiber diameter, the density of the surface layer can be made slightly higher to increase the number of constituent fibers, reducing the stress on each linear body to improve stress distribution and also improving cushioning that supports the buttocks, thereby improving seating comfort. The base layer can be made slightly harder by increasing the fiber diameter, and to make it a denser layer responsible for vibration absorption and body shape retention, it can be made of linear bodies with a slightly thinner fiber diameter and a higher density. This allows vibrations and rebound stresses received from the seat frame surface to be uniformly transmitted to the base layer, enabling the whole to deform and convert energy, improving seating comfort and also improving the durability of the cushion. Furthermore, the fiber diameter can be made slightly thinner in some areas to increase density in order to give thickness and tension to the sides of the seat. In this way, each layer can be arbitrarily selected to have a desirable density and fiber diameter according to its purpose. The thickness of each layer of the mesh structure is not particularly limited, but it is preferably 3 mm or more, and more preferably 5 mm or more, as this facilitates the development of its cushioning function.

[0026] The outer surface of the mesh structure preferably has a surface layer in which the curved linear bodies are bent by 30° or more, preferably 45° or more, in the middle, making the surface substantially flat, and most of the contact points are fused. As a result, the contact points of the linear bodies on the mesh structure surface are greatly increased and adhesive points are formed, so that localized external forces on the buttocks when sitting are absorbed by the structural surface without causing a feeling of foreign body to the buttocks, the surface structure as a whole deforms and the entire internal structure also deforms and absorbs stress, and when the stress is released the rubber elasticity of the elastic resin is activated and the structure can recover to its original form. If it is not substantially flattened, it may cause a feeling of foreign body to the buttocks, localized external forces may be applied to the surface, selective stress concentration may occur up to the linear bodies and adhesive points on the surface, and fatigue due to stress concentration may occur and the resistance to deformation may decrease. If the outer surface of the structure is flattened, it can be made into a seat or chair for automobiles, railways, etc., or a cushion mat for beds, sofas, futons, etc., by laminating a wadding layer (either without using a wadding layer or by laminating a very thin wadding layer) and covering the surface with a cover fabric. If the outer surface of the structure is not flattened, it is necessary to laminate a relatively thick (preferably 10 mm or more) wadding layer onto the surface of the mesh structure and cover the surface with a cover fabric to form a seat or cushion mat. Adhesion to the wadding layer or the cover fabric is easy if the surface is flat, but if it is not flattened, the uneven surface will result in incomplete adhesion.

[0027] Next, a method for manufacturing a mesh structure consisting of a three-dimensional random loop joint structure according to the present invention will be described. The following method is an example and is not limited thereto. The mesh structure of the present invention is manufactured by melt spinning. First, (1) the molten discharge lines are bent and brought into contact with each other, and a three-dimensional structure is formed by fusing most of the contact parts, while (2) they are sandwiched in a take-up device. Then, (3) they are cooled in a cooling tank to form a mesh structure. In the present invention, each thermoplastic elastomer is distributed in front of each nozzle orifice so that the discharge lines can be composited with polyester thermoplastic elastomer and polystyrene thermoplastic elastomer, and the thermoplastic elastomers are discharged downward from the nozzle at a melting temperature of 10°C or more above the melting point of the high-melting-point component and 120°C or less below the melting point of the low-melting-point component, thereby manufacturing a mesh structure consisting of a continuous linear body composited from the molten composite discharge lines by the above method.

[0028] Polyester-based thermoplastic elastomers and polystyrene-based thermoplastic elastomers are melted separately using a general melt extruder, and then mixed and extruded in a manner similar to general composite spinning methods, so that they are composited just before the orifice. When spinning a continuous linear material with a sheath-core structure, the core component is supplied from the center, and the sheath component is added around it and extruded. When spinning a continuous linear material with a side-by-side structure, the components are added from the left and right or front and back and extruded. In this case, the melting temperature must be 120°C or less below the melting point of the low-melting-point component, otherwise thermal decomposition will be significant and the properties of the thermoplastic resin will deteriorate, which is undesirable. On the other hand, if the melting temperature is not 10°C or more above the melting point of the high-melting-point component, melt fracture will occur and normal linear formation will not be possible. Also, in the case of a side-by-side structure, linear adhesion may be poor. The preferred melting temperature is 20°C to 100°C above the melting point of the low-melting-point component, more preferably 30°C to 80°C above the melting point of the high-melting-point component, and the components are merged and discharged at the same melting temperature, which is 15°C to 40°C above the melting point of the high-melting-point component, more preferably 20°C to 30°C above the melting point of the high-melting-point component. If the difference in melting temperatures immediately before merging is not 10°C or less, abnormal flow may occur and the formation of the composite form may be impaired.

[0029] The shape of the orifice is not particularly limited, but it is especially preferable to use an irregular cross-section (for example, a triangular, Y-shaped, or star-shaped cross-section, which increases the second moment of area) or a hollow cross-section (for example, a triangular hollow, a round hollow, or a hollow with a protrusion) because it makes it difficult for the three-dimensional structure formed by the discharge line in the molten state to relax, and conversely, it allows for a longer flow time at the contact point, thus strengthening the bonding point. When heating for bonding as described in Japanese Patent Application Publication No. 1-2075, the three-dimensional structure tends to relax and become planar, making it difficult to maintain a three-dimensional structure, which is undesirable. The effect of improving the properties of the structure is that the apparent bulk can be increased and the weight reduced, as well as the compressive resistance and elasticity can be improved, making it less prone to sagging. In the case of a hollow cross-section, if the hollow ratio exceeds 80%, the cross-section tends to collapse, so when adopting a hollow cross-section, the hollow ratio is preferably 10% to 70%, more preferably 20% to 60%, so that the effect of weight reduction can be achieved.

[0030] The orifice's hole pitch must be such that the loops formed by the linear fibers can make sufficient contact. To create a structure with high density of continuous linear fibers, the hole pitch should be shortened, and to create a structure with low density of continuous linear fibers, the hole pitch should be lengthened. The hole pitch in this invention is preferably 3 mm to 20 mm, more preferably 5 mm to 10 mm. In this invention, different densities and different fiber diameters can be created as desired. Different density layers can be formed by changing the pitch between rows or the pitch between holes, or by changing both the pitch between rows and the pitch between holes. Furthermore, by changing the cross-sectional area of ​​the orifice to introduce a difference in pressure loss during discharge, different fiber diameters can be created using the principle that the amount of molten thermoplastic elastomer extruded from the same nozzle at a constant pressure decreases with increasing pressure loss at the orifice.

[0031] Next, the two outer surfaces of the molten three-dimensional structure are sandwiched between a take-up net, and the molten, winding, continuously extruded linear material on both outer surfaces is bent and deformed by 30° or more, flattening the outer surface and simultaneously bonding the contact points with the unbent extruded linear material to form a structure. After that, it is rapidly cooled in a cooling medium (usually room temperature water is preferred as it allows for a faster cooling rate and is also cost-effective) to obtain a mesh structure consisting of the three-dimensional random loop joint structure of the present invention. Next, it is dewatered and dried, but adding surfactants or the like to the cooling medium is undesirable as it can make dewatering and drying difficult, or cause the thermoplastic elastomer to swell. A preferred method of the present invention is to perform a pseudo-crystallization treatment after cooling. The pseudo-crystallization treatment temperature is at least 10°C lower than the melting point (Tm) and above the α-dispersion rise temperature of Tanδ (Tαcr). This process significantly improves heat resistance and fatigue resistance compared to materials that have an endothermic peak below the melting point and have not undergone pseudo-crystallization treatment (i.e., those without an endothermic peak). The preferred pseudo-crystallization treatment temperature for this invention is from (Tαcr + 10°C) to (Tm - 20°C). Pseudo-crystallization by simple heat treatment improves heat resistance and fatigue resistance. Furthermore, it is more preferable to apply compressive deformation of 10% or more after cooling and then perform annealing, as this significantly improves heat resistance and fatigue resistance. In addition, if a drying process is performed after cooling, the drying temperature can be set to the annealing temperature, allowing for simultaneous pseudo-crystallization treatment. Alternatively, pseudo-crystallization treatment can be performed separately.

[0032] Next, the mesh structure is cut to the desired length or shape and used as a cushioning material. When using the mesh structure of the present invention as a cushioning material, it is necessary to select the resin, fiber diameter, loop diameter, and bulk density depending on the purpose and part of use. For example, when used for surface wadding, it is preferable to use a low density, thin fiber diameter, and fine loop diameter to provide a soft touch, moderate sinking, and firm bulge. For the middle layer cushioning body, it is preferable to use a medium density, thick fiber diameter, and slightly larger loop diameter to lower the resonant frequency, improve shape retention by linearly changing the hysteresis during compression, and maintain durability. Of course, it is also possible to use it in combination with other materials, such as hard cotton cushioning material made of short fiber aggregates, nonwoven fabrics, etc., to meet the required performance in relation to the application. Furthermore, even outside the resin manufacturing process, within the limits that do not degrade performance, the molded product can be processed from the manufacturing process to any stage of product development to impart functions such as flame retardancy, insect repellency, antibacterial properties, heat resistance, water and oil repellency, coloring, and fragrance through treatments such as the addition of chemicals.

[0033] The present invention will be described in detail below with reference to examples. The evaluations in the examples were performed using the following methods.

[0034] <Resin Properties> (1) Rebound modulus: Measured according to JIS K 6255 standard. (2) Melting point: Using a Shimadzu TA50 and DSC50 differential thermal analyzer, the endothermic peak (melting peak) temperature was determined from the endothermic / exothermic curve measured from 20°C to 250°C at a heating rate of 20°C / min for a 10g sample. (3) Shore D hardness: Measured according to ASTM D2240 standard.

[0035] <Reticulated Structure Characteristics> (4) Hardness at 25% Compression The sample was cut to a size of 30 cm x 30 cm and left unloaded for 24 hours in an environment of 20°C ± 2°C. Then, using a φ200 mm, 10 mm thick pressure plate, the center of the sample was compressed at a speed of 10 mm / min in an A&D Company Tensilon (RTG-1310) in an environment of 20°C ± 2°C. The thickness was measured when the load reached 1.0 N and was taken as the hardness tester thickness. Taking the position of the pressure plate at this time as the zero point, the sample was compressed to 75% of the hardness tester thickness at a speed of 100 mm / min, and then the pressure plate was returned to the zero point at a speed of 100 mm / min. Subsequently, it was compressed to 25% of the hardness tester thickness at a speed of 100 mm / min, and the load at this time was taken as the hardness at 25% compression. The unit of the hardness at 25% compression is kg / φ200 mm and is shown as the average value for n=3. (5) Fiber diameter of continuous linear material The sample was cut to a size of 10 cm in width x 10 cm in length x sample thickness, and 10 linear materials of approximately 5 mm in length were randomly collected from the cut surface in the thickness direction. The thickness of the collected linear materials was measured by focusing an optical microscope at an appropriate magnification on the fiber diameter measurement site and viewing the fiber thickness from the side of the fiber. Note that since the surface of the mesh structure is flattened to obtain smoothness, the fiber cross-section may be deformed, so samples were not taken from an area within 2 mm of the surface of the mesh structure. (6) Hollow ratio of continuous linear material Continuous linear material was collected from the mesh structure, cooled with liquid nitrogen, and then cut. The cross-section was observed with an electron microscope at a magnification of 50x, and the obtained image was analyzed with a CAD system to measure the cross-sectional area of ​​the resin part (A) and the cross-sectional area of ​​the hollow part (B), and the hollow ratio was calculated using the formula {B / (A+B)}×100. (7) Compression residual strain at 70°C The sample is cut to a size of 10 cm × 10 cm × sample thickness, and the thickness before compression is t b The sample, after being measured, was placed in a jig capable of maintaining a 50% compressed state and left in a dryer set to 70±2°C for 22 hours. The sample was then removed, the compressive strain was removed, and it was cooled to room temperature (25°C) for 30 minutes. The compressed thickness t was then left to stand. a Find the equation (t b -t a ) / t b The compression residual strain at 70°C was calculated from ×100: unit % (average value for n=3). Here, the thickness before compression t is shown. band the thickness t after compression a The height at one location of each sample before and after compression was measured, and the average value was taken as the thickness. (8) Rebound resilience of the network structure The sample was cut into a size of 10 cm in the width direction × 10 cm in the length direction × the sample thickness, left unloaded for 24 hours in an environment of 20°C ± 2°C, and then, using a tensilon (RTG-1310) manufactured by A&D Company Limited in an environment of 20°C ± 2°C, with a pressure plate of φ200 mm and a thickness of 10 mm, compression of the sample was started at a speed of 10 mm / min. When the load reached 5.0 N, the thickness was measured. Taking the position of the pressure plate at this time as the zero point, after compressing to 75% of the hardness tester thickness at a speed of 100 mm / min, the pressure plate was returned to the zero point at a speed of 100 mm / min. In a continuous operation, after compressing to 75% of the hardness tester thickness at a speed of 100 mm / min, the pressure plate was returned to the zero point at a speed of 100 mm / min. After the sample was left standing for 15 minutes, a cylindrical weight with a diameter of 80 mm and a weight of 600 g was dropped from a height of 15 cm, and the height of the first bounce was determined. The rebound resilience was determined from the following formula. The height of the bounce was measured with a high-speed digital camera (average value of n = 3). Rebound resilience (%) = (height of bounce (cm) / 15 (cm)) × 100 (9) Apparent density The sample was cut into a size of 15 cm × 15 cm, the height at four locations was measured, the volume was determined, and the value obtained by dividing the weight of the sample by the volume (g / cm ３ ) is shown. (Average value of n = 4)

[0036] <Synthesis Example 1> Dimethyl terephthalate (DMT), 1,4-butanediol (1,4-BD), and polytetramethylene glycol (PTMG: average molecular weight 2000) were charged with a small amount of catalyst, and after transesterification by a conventional method, polycondensation was carried out while raising the temperature and reducing the pressure to produce a polyester ether block copolymer elastomer with a DMT / 1,4-BD / PTMG of 100 / 75 / 25 (molar ratio). Then, 1% of an antioxidant was added, mixed, kneaded, and pelletized, and vacuum dried at 50°C for 48 hours to obtain a polyester-based thermoplastic elastomer (A-1). Its properties are shown in Table 1.

[0037] <Synthesis Example 2> Dimethyl terephthalate (DMT), 1,4-butanediol (1,4-BD), and polytetramethylene glycol (PTMG: average molecular weight 1000) were charged with a small amount of catalyst. After transesterification by a conventional method, polycondensation was carried out while raising the temperature and reducing the pressure to produce a polyester ether block copolymer elastomer with DMT / 1,4-BD / PTMG of 100 / 71.8 / 28.2 (mol ratio). Then, 1% of an antioxidant was added, mixed, kneaded, pelletized, and vacuum dried at 50°C for 48 hours to obtain a polyester-based thermoplastic elastomer (A-2). Its properties are shown in Table 1.

[0038] <Synthesis Example 3> Dimethyl terephthalate (DMT), 1,4-butanediol (1,4-BD), and polytetramethylene glycol (PTMG: average molecular weight 1000) were charged with a small amount of catalyst. After transesterification by a conventional method, polycondensation was carried out while raising the temperature and reducing the pressure to produce a polyester ether block copolymer elastomer with DMT / 1,4-BD / PTMG of 100 / 84 / 16 (mol ratio). Then, 1% of an antioxidant was added, mixed, kneaded, pelletized, and vacuum dried at 50°C for 48 hours to obtain a polyester-based thermoplastic elastomer (A-3). Its properties are shown in Table 1.

[0039]

[0040] <Example 1> The polyester thermoplastic elastomer (A-1) obtained in Synthesis Example 1 and a hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), which is a polystyrene thermoplastic elastomer, were melted at 240°C and merged in front of the orifice in a volume ratio of 30 / 70, with the sheath / core being A-1 / TPS. The mixture was then discharged at 240°C at a total discharge rate of 1000 g / min from a nozzle equipped with an orifice with a hole diameter of 1.0 mm for forming a continuous linear material with a circular hollow cross-section, where the row pitch in the longitudinal direction was 5 mm and the hole pitch in the width direction was 10 mm, on the effective surface of the nozzle, which was 50 cm wide x 5 cm long. Cooling water was placed 25 cm below the nozzle surface, and a pair of pull-up conveyors were placed parallel to a 60 cm wide stainless steel endless net at 5 cm intervals, with a portion of them protruding above the water surface. The discharged continuous linear material was pulled up onto the conveyors, and while fusing the contact points of the continuous linear material, both sides were sandwiched together and the material was pulled into the 25°C cooling water at a speed of 0.66 m / min to solidify. Next, after a pseudo-crystallization treatment in a 105°C hot air dryer for 20 minutes, the material was cut to a predetermined size to obtain a mesh structure consisting of a composite continuous linear material. The properties of the obtained mesh structure are shown in Table 2.

[0041] <Example 2> A mesh structure was obtained in the same manner as in Example 1, except that the polyester thermoplastic elastomer (A-1) obtained in Synthesis Example 1 and a hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), which is a polystyrene thermoplastic elastomer, were mixed in a volume ratio of 50 / 50 so that the sheath / core was A-1 / TPS. The properties of the obtained mesh structure are shown in Table 2.

[0042] <Example 3> A mesh structure was obtained in the same manner as in Example 1, except that the polyester thermoplastic elastomer (A-1) obtained in Synthesis Example 1 and a hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), which is a polystyrene thermoplastic elastomer, were combined in a volume ratio of 10 / 90 so that the sheath / core was A-1 / TPS. The properties of the obtained mesh structure are shown in Table 2.

[0043] <Example 4> A mesh structure was obtained in the same manner as in Example 1, except that the polyester thermoplastic elastomer (A-2) obtained in Synthesis Example 1 and a hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), which is a polystyrene thermoplastic elastomer, were combined in a volume ratio of 50 / 50 so that the sheath / core was A-2 / TPS. The properties of the obtained mesh structure are shown in Table 2.

[0044] <Comparative Example 1> A mesh structure was obtained in the same manner as in Example 1, except that the polyester thermoplastic elastomer (A-3) obtained in Synthesis Example 3 and a hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), which is a polystyrene thermoplastic elastomer, were mixed in a volume ratio of 30 / 70 so that the sheath / core was A-3 / TPS. The properties of the obtained mesh structure are shown in Table 2.

[0045] <Comparative Example 2> A mesh structure was obtained in the same manner as in Comparative Example 1, except that the volume ratio was changed to 70 / 30. The properties of the obtained mesh structure are shown in Table 2.

[0046] <Comparative Example 3> Hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), a polystyrene-based thermoplastic elastomer, was melted at 240°C and discharged at a total discharge rate of 1000 g / min from a nozzle equipped with 1.0 mm diameter orifices for forming a continuous linear material with a circular hollow cross-section, arranged on a nozzle effective surface of 65 cm wide x 5 cm long with a row pitch of 5.2 mm in the width direction and a row pitch of 6.0 mm in the length direction, at 240°C. Cooling water was placed 25 cm below the nozzle surface, and a pair of pull-up conveyors were placed parallel to a 70 cm wide stainless steel endless net at 5 cm intervals so that part of them was above the water surface. The discharged continuous linear material was pulled into the cooling water at a speed of 0.66 m / min, solidifying while fusing the contact parts of the continuous linear material and sandwiching both sides. Next, the material was subjected to a pseudo-crystallization treatment in a 70°C hot air dryer for 15 minutes, and then cut to a predetermined size to obtain a mesh structure. The properties of the obtained mesh structure are shown in Table 2.

[0047] <Comparative Example 4> A mesh structure was obtained in the same manner as in Comparative Example 3, except that the hydrogenated styrene-butadiene random copolymer (TPS), which is a polystyrene-based thermoplastic elastomer, was replaced with the polyester-based thermoplastic elastomer (A-3) obtained in Synthesis Example 3, and the temperature of the hot air dryer was changed to 105°C. The properties of the obtained mesh structure are shown in Table 2.

[0048] <Comparative Example 5> A mesh structure was obtained in the same manner as in Comparative Example 3, except that the hydrogenated styrene-butadiene random copolymer (TPS), which is a polystyrene-based thermoplastic elastomer, was replaced with the polyester-based thermoplastic elastomer (A-2) obtained in Synthesis Example 2, and the temperature of the hot air dryer was changed to 105°C and the discharge temperature was changed to 220°C. The properties of the obtained mesh structure are shown in Table 2.

[0049] <Comparative Example 6> A mesh structure was obtained in the same manner as in Comparative Example 2, except that the hydrogenated styrene-butadiene random copolymer (TPS), which is a polystyrene-based thermoplastic elastomer, was replaced with the polyester-based thermoplastic elastomer (A-1) obtained in Synthesis Example 1, and the temperature of the hot air dryer was changed to 105°C and the discharge temperature was changed to 220°C. The properties of the obtained mesh structure are shown in Table 2.

[0050]

[0051] <Example 5> The polyester thermoplastic elastomer (A-1) obtained in Synthesis Example 1 and a hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), which is a polystyrene thermoplastic elastomer, were melted at 240°C and merged in front of the orifice in a volume ratio of 40 / 60, with the sheath / core being A-1 / TPS. The mixture was then discharged at 240°C at a total discharge rate of 1000 g / min from a nozzle equipped with an orifice with a hole diameter of 1.0 mm for forming a continuous linear material with a circular hollow cross-section, where the row pitch in the longitudinal direction was 5 mm and the hole pitch in the width direction was 10 mm, on the effective surface of the nozzle, which was 50 cm wide x 5 cm long. Cooling water was placed 25 cm below the nozzle surface, and a pair of pull-in conveyors were placed parallel to a 60 cm wide stainless steel endless net at 5 cm intervals, with a portion of them protruding above the water surface. The discharged continuous linear material was pulled in at a speed of 0.66 m / min into 25°C cooling water, solidifying while fusing the contact points of the continuous linear material and sandwiching both sides. Next, after a pseudo-crystallization treatment in a 105°C hot air dryer for 20 minutes, it was cut to a predetermined size to obtain a mesh structure consisting of a composite continuous linear material. The properties of the obtained mesh structure are shown in Table 3.

[0052] <Example 6> A mesh structure was obtained in the same manner as in Example 5, except that the polyester thermoplastic elastomer (A-1) obtained in Synthesis Example 1 and a hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), which is a polystyrene thermoplastic elastomer, were combined in a volume ratio of 60 / 40 so that the sheath / core was A-1 / TPS. The properties of the obtained mesh structure are shown in Table 3.

[0053] <Example 7> A mesh structure was obtained in the same manner as in Example 5, except that the polyester thermoplastic elastomer (A-1) obtained in Synthesis Example 1 and a hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), which is a polystyrene thermoplastic elastomer, were mixed in a volume ratio of 20 / 80 so that the sheath / core was A-1 / TPS. The properties of the obtained mesh structure are shown in Table 3.

[0054] <Example 8> A mesh structure was obtained in the same manner as in Example 5, except that the polyester thermoplastic elastomer (A-2) obtained in Synthesis Example 2 and a hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), which is a polystyrene thermoplastic elastomer, were combined in a volume ratio of 60 / 40 so that the sheath / core was A-2 / TPS. The properties of the obtained mesh structure are shown in Table 3.

[0055] <Comparative Example 7> A mesh structure was obtained in the same manner as in Example 5, except that the polyester thermoplastic elastomer (A-3) obtained in Synthesis Example 3 and a hydrogenated styrene-butadiene random copolymer (TPS) (Asahi Kasei Chemicals "S.O.E.S1611"), which is a polystyrene thermoplastic elastomer, were combined in a volume ratio of 40 / 60 so that the sheath / core was A-3 / TPS. The properties of the obtained mesh structure are shown in Table 3.

[0056] <Comparative Example 8> A mesh structure was obtained in the same manner as in Comparative Example 7, except that the volume ratio was changed to 60 / 40. The properties of the obtained mesh structure are shown in Table 3.

[0057] <Comparative Example 9> Hydrogenated styrene-butadiene random copolymer (TPS) (S.O.E.S1611, manufactured by Asahi Kasei Chemicals), a polystyrene-based thermoplastic elastomer, was melted at 240°C and discharged at a total discharge rate of 1000 g / min from a nozzle equipped with 1.0 mm diameter orifices for forming a continuous linear body with a circular hollow cross-section, arranged on a nozzle effective surface of 65 cm wide x 5 cm long with a hole pitch of 5.2 mm in the width direction and a hole pitch of 6.0 mm in the length direction, at 240°C. Cooling water was placed 25 cm below the nozzle surface, and a pair of pull-up conveyors were placed parallel to a 70 cm wide stainless steel endless net at 5 cm intervals so that part of them were above the water surface. The discharged continuous linear body was pulled into the cooling water at a speed of 0.66 m / min, solidifying while fusing the contact parts of the continuous linear body and sandwiching both sides. Next, the material was subjected to a pseudo-crystallization treatment in a 70°C hot air dryer for 15 minutes, and then cut to a predetermined size to obtain a mesh structure. The properties of the obtained mesh structure are shown in Table 3.

[0058] <Comparative Example 10> A mesh structure was obtained in the same manner as in Comparative Example 9, except that the hydrogenated styrene-butadiene random copolymer (TPS), which is a polystyrene-based thermoplastic elastomer, was replaced with the polyester-based thermoplastic elastomer (A-3) obtained in Synthesis Example 3, and the temperature of the hot air dryer was changed to 105°C. The properties of the obtained mesh structure are shown in Table 3.

[0059] <Comparative Example 11> A mesh structure was obtained in the same manner as in Comparative Example 9, except that the hydrogenated styrene-butadiene random copolymer (TPS), which is a polystyrene-based thermoplastic elastomer, was replaced with the polyester-based thermoplastic elastomer (A-2) obtained in Synthesis Example 2, and the temperature of the hot air dryer was changed to 105°C. The properties of the obtained mesh structure are shown in Table 3.

[0060] <Comparative Example 12> A mesh structure was obtained in the same manner as in Comparative Example 8, except that the hydrogenated styrene-butadiene random copolymer (TPS), which is a polystyrene-based thermoplastic elastomer, was replaced with the polyester-based thermoplastic elastomer (A-1) obtained in Synthesis Example 1, and the temperature of the hot air dryer was changed to 105°C. The properties of the obtained mesh structure are shown in Table 3.

[0061]

[0062] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered restrictive in any way. The scope of the present invention is defined by the claims rather than the embodiments and examples described above, and all modifications within the meaning and scope of the claims are intended to be included.

[0063] The mesh structure of the present invention exhibits high vibration absorption and excellent heat resistance and deformation resistance, and can be suitably used in vehicle seats, bedding, and the like, taking advantage of these characteristics.

Claims

1. A three-dimensional random loop bonded network structure consisting of a continuous linear body of thermoplastic elastomer with a fiber diameter of not less than 0.1 mm and not more than 3.0 mm, where the continuous linear body of the thermoplastic elastomer is complexed with thermoplastic elastomers including polyester-based thermoplastic elastomers and polystyrene-based thermoplastic elastomers, and the network structure has a residual stress at 70°C of not more than 35% and a rebound resilience of not more than 10%.

2. A network structure according to claim 1 where the polyester-based thermoplastic elastomer has a rebound resilience of not less than 75%.

3. A network structure according to claim 1 where the polyester-based thermoplastic elastomer has a Shore D stiffness of not more than 40. 4.

5. Any network structure under claims 1 through 3 in which a polyester-based thermoplastic elastomer has a melting point below 200°C.

6. Any network structure under claims 1 through 4 consists of a continuous linear framework of thermoplastic elastomer complexes in which the volume ratio of the polyester-based thermoplastic elastomer to the polystyrene-based thermoplastic elastomer is 90 / 10 to 10 / 90.

7. Any network structure under claims 1 through 5 in which the complex structure of the continuous linear framework of the thermoplastic elastomer is a sheath-core structure or a side-by-side structure.

8. Any network structure under claims 1 through 6 in which a polyester-based thermoplastic elastomer is at least one polyester ether block copolymer or polyester ester block copolymer.

9. Any network structure under claims 1 through 7 in which at least one polystyrene-based thermoplastic elastomer is selected from a group consisting of styrene-butadiene copolymer, styrene-isoprene copolymer, and hydrogenated copolymer.

10. Any network structure under claims 1 through 8 in which the continuous linear thermoplastic elastomer has a hollow cross-section.

11. Any network structure under claims 1 through 9 in which the continuous linear thermoplastic elastomer has a modified cross-section.