Three-dimensional network structure

Abstract

[Problem] To provide a three dimensional network structure body that has excellent hydrolysis resistance and that is unlikely to degrade due to moisture in the air when used for an extended period of time. [Solution] This three dimensional network structure body is formed of a continuous filament made of a resin composition containing a polyester-based thermoplastic elastomer and a phosphate glass, and has a three dimensional random loop joined structure. The phosphate glass contains P2O5, SiO2, and ZnO, and preferably contains at least one selected from alkali metal oxides and alkaline earth metals.

Description

[Technical Field]

[0001] The present invention relates to a three-dimensional mesh structure suitable for cushioning materials used in office chairs, furniture, sofas, bedding such as beds, vehicle seats for trains, automobiles, motorcycles, child seats, strollers, etc., floor mats, shock-absorbing mats such as collision and pinch prevention members, etc. [Background technology]

[0002] Currently, foamed cross-linked urethanes are widely used as cushioning materials for furniture, bedding, and vehicle seats for trains, automobiles, and motorcycles due to their excellent durability and processability. However, foamed cross-linked urethanes have poor moisture permeability and breathability, and their heat retention makes them prone to stuffiness. Furthermore, because foamed cross-linked urethanes are not thermoplastic, recycling them is difficult. Incineration of foamed cross-linked urethanes has been noted as a major problem, as has the cost of removing toxic gases generated during incineration. Therefore, unwanted foamed cross-linked urethanes are often disposed of in landfills. However, difficulties in stabilizing the ground limit landfill sites and increase landfill costs. Various issues have also been noted, including pollution from the chemicals used in manufacturing, residual chemicals after foaming, and the resulting odors.

[0003] Patent Document 1 discloses a three-dimensional network structure made of continuous filaments of a thermoplastic resin composition and having a three-dimensional random loop bonded structure. This structure solves the problems associated with the aforementioned "expanded-crosslinked urethane" and also has excellent cushioning performance. However, when this three-dimensional network structure is used in products such as bedding or vehicle seats, it is exposed to moisture in the air for a long period of time, which causes the resin composition that makes up the three-dimensional network structure to hydrolyze and deteriorate, leaving room for improvement.

[0004] Furthermore, Patent Document 2 discloses a three-dimensional network structure that exhibits excellent hydrolysis resistance during high-temperature heating and remelting. This document describes that by keeping the acid value of the thermoplastic elastomer low, it is possible to suppress hydrolysis that occurs during the thermal processing step of heating the elastomer to a high temperature close to the melting temperature and during the remelting step during recycling. However, when used as a product, the effect of suppressing hydrolysis of the resin caused by long-term exposure to moisture in the air is insufficient. Therefore, there is room for improvement in terms of suppressing deterioration of the resin composition that constitutes the three-dimensional network structure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 07-68061 [Patent Document 2] International Publication No. 2017 / 065260 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a three-dimensional network structure having excellent hydrolysis resistance. [Means for solving the problem]

[0007] The present invention, which has been able to solve the above problems, is as follows. [1] A three-dimensional network structure made of a polyester-based thermoplastic elastomer resin composition and having a three-dimensional random loop bonded structure composed of continuous filaments, The resin composition has a three-dimensional network structure containing phosphate glass. [2] The phosphate glass is P2O5, SiO 2、 and ZnO, and further containing at least one selected from alkali metal oxides and alkaline earth metals. [Effects of the Invention]

[0008] The three-dimensional network structure of the present invention has excellent hydrolysis resistance due to the polyester-based thermoplastic elastomer resin composition that constitutes the three-dimensional network structure, and is resistant to deterioration due to moisture in the air during long-term use. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below. The three-dimensional network structure of the present invention is composed of a resin composition containing a polyester-based thermoplastic elastomer and phosphate glass. When the three-dimensional network structure of the present invention comes into contact with moisture in the air, phosphorus, a component of the phosphate glass contained in the resin composition, dissolves in the moisture, thereby consuming the moisture and suppressing hydrolysis of the polyester-based thermoplastic elastomer resin composition.

[0010] Next, the phosphate glass will be described. Phosphate glass refers to a composite glass that contains at least diphosphorus pentoxide (P2O5) as a network-forming oxide, and of the three network-forming oxides diboron trioxide (B2O3), silicon dioxide (SiO2), and diphosphorus pentoxide (P2O5), it has the highest content of diphosphorus pentoxide (P2O5). Specifically, P2O5, SiO 2、 and ZnO, and composite glasses containing at least one selected from alkali metal oxides and alkaline earth metals. Examples of alkali metal oxides include K2O, Na2O, and Li2O. Examples of alkaline earth metal oxides include MgO and CaO. In addition, Ag2O, GeO2, BeF2, As2S3, CuO, TiO2, LaO3, ZrO2, MoO3, GeS2, etc. may be contained within the range that does not impair the properties.

[0011] Phosphate glass contains a relatively large amount of P2O5. In order to efficiently inhibit the hydrolysis of the polyester-based thermoplastic elastomer, the molar ratio of phosphorus atoms to silicon atoms (P / Si) of the phosphate glass is preferably 1 or more, more preferably 5 or more, even more preferably 8 or more, and particularly preferably 10 or more. If the molar ratio (P / Si) is less than 1, the phosphate glass tends to have a slower rate of boron elution in water. Therefore, the hydrolysis inhibition efficiency is likely to decrease. Furthermore, unless the content of phosphate glass in the three-dimensional network structure is increased, the hydrolysis inhibition efficiency is likely to decrease. On the other hand, from the viewpoint of heat resistance and chemical durability, the molar ratio (P / Si) of the phosphate glass is preferably 20 or less, more preferably 18 or less, and particularly preferably 15 or less.

[0012] An example of the composition of such phosphate glass is phosphate glass containing 20 to 60 mol % of P2O5 and 1 to 30 mol % of SiO2. The phosphate glass may be in the form of a polyhedron or sphere, such as a fine powder, frit, particles, beads, etc. When the phosphate glass is in the form of a polyhedron or sphere, the average particle size of the phosphate glass is preferably 0.1 μm or more, more preferably 0.5 μm or more, and particularly preferably 1 μm or more, in order to suppress the occurrence of secondary aggregation during spinning and the cost of pulverization. On the other hand, when the phosphate glass is polyhedral or spherical, the average particle size of the phosphate glass is preferably 100 μm or less, more preferably 50 μm or less, and particularly preferably 30 μm or less, in order to suppress an increase in back pressure during spinning.

[0013] Phosphate glass is generally produced by the melt-grinding method, in which raw materials such as P2O5, SiO2, and alkali metal oxides are mixed in a predetermined composition ratio, melted at high temperature, and then rapidly cooled to form glass pieces, which are then pulverized using a ball mill or similar. Such phosphate glasses are available from, for example, Nippon Electric Glass, Nippon Frit, Ishizuka Glass, Koa Glass, Toagosei, Toyo Glass, Potters Ballotini, and the like, but are not limited to these.

[0014] The three-dimensional network structure of the present invention preferably has a phosphorus content derived from the phosphate glass of 5 ppm or more by mass relative to the three-dimensional network structure. By including 5 ppm or more by mass of phosphorus derived from the phosphate glass relative to the three-dimensional network structure, as described above, when the phosphate glass comes into contact with moisture in the air, the phosphorus dissolves in the moisture, consuming the moisture and exhibiting the effect of suppressing hydrolysis of the resin composition due to moisture in the air. From the viewpoint of the effect of suppressing hydrolysis of the resin composition due to moisture in the air, the content of phosphorus derived from the phosphate glass in the three-dimensional network structure is preferably 10 ppm or more by mass, more preferably 15 ppm or more, particularly preferably 150 ppm or more, and most preferably 400 ppm or more. Furthermore, by adding silver oxide, copper oxide, or zinc oxide to the phosphate glass, the effect of suppressing bacterial growth on the fibers of the three-dimensional network structure can also be expected. On the other hand, if the content of phosphorus derived from the phosphate glass relative to the three-dimensional network structure is too high, the continuous filaments constituting the three-dimensional network structure become brittle, and the mechanical properties (e.g., dynamic durability) of the three-dimensional network structure tend to deteriorate. Therefore, from the viewpoint of minimizing the influence on the mechanical properties of the three-dimensional network structure, the content of phosphorus derived from the phosphate glass relative to the three-dimensional network structure is preferably 36,000 ppm or less by mass, more preferably 18,000 ppm or less, even more preferably 10,000 ppm or less, particularly preferably 5,000 ppm or less, and most preferably 2,500 ppm or less.

[0015] Next, the polyester-based thermoplastic elastomer used in the present invention will be described. Examples of polyester-based thermoplastic elastomers include polyester ether block copolymers having a thermoplastic polyester as a hard segment and a polyalkylene diol as a soft segment, and polyester block copolymers having an aliphatic polyester as a soft segment.

[0016] The polyester ether block copolymer may be a copolymer of 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 sebacic acid dimer acid, or ester-forming derivatives thereof, and 1,4-butanediol, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, The copolymer is a ternary block copolymer composed of at least one diol component selected from aliphatic diols such as ethylene glycol and hexamethylene glycol, alicyclic diols such as 1,1-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, or ester-forming derivatives thereof, and at least one polyalkylene diol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or glycols composed of ethylene oxide-propylene oxide copolymers, having a number average molecular weight of about 300 to 5,000.

[0017] Examples of polyester ester block copolymers include triblock copolymers composed of at least one of the above dicarboxylic acids and diols, and polyester diols such as polylactones with number-average molecular weights of approximately 300 to 5,000. Considering thermal adhesiveness, hydrolysis resistance, stretchability, heat resistance, etc., triblock copolymers of terephthalic acid and / or naphthalene 2,6-dicarboxylic acid as the dicarboxylic acid, 1,4-butanediol as the diol component, and polytetramethylene glycol as the polyalkylene diol, or triblock copolymers of polylactone as the polyester diol, are particularly preferred. In special cases, those incorporating polysiloxane-based soft segments can also be used.

[0018] The polyester thermoplastic elastomer also includes a blend or copolymer of the above polyester thermoplastic elastomer with a non-elastomer component, a soft segment containing a polyolefin component, etc. Furthermore, the polyester thermoplastic elastomer also includes a polyester thermoplastic elastomer to which various additives are added as needed.

[0019] The polyester-based thermoplastic elastomer containing phosphate glass can be obtained, for example, as follows. The polyester thermoplastic elastomer is polymerized by a conventional method and then pelletized. The resulting polyester thermoplastic elastomer pellets are mixed with the phosphate glass fine powder at a predetermined blending ratio, melt-extruded in a twin-screw extruder, cooled, pelletized, and dried to obtain a polyester thermoplastic elastomer resin composition containing the phosphate glass. Alternatively, pellets of the polyester-based thermoplastic elastomer are melt-extruded in a twin-screw extruder, while the phosphate glass fine powder is supplied at a predetermined blending ratio from a side feeder installed in the extruder, and the polyester-based thermoplastic elastomer and the phosphate glass are melt-extruded while being kneaded and mixed in the extruder, followed by cooling, pelletizing, and drying, thereby obtaining a resin composition of the polyester-based thermoplastic elastomer containing the phosphate glass.

[0020] The amount of the phosphate glass added is preferably in the range of 0.001 to 50% by mass when the resin composition is taken as 100% by mass. If the amount of the phosphate glass added is less than 0.001% by mass, the phosphate glass content in the resin composition will vary greatly. If the amount of the phosphate glass added exceeds 50% by mass, the high phosphate glass content makes it difficult to produce the resin composition. The amount of the phosphate glass added is preferably 0.01 to 20% by mass in view of the variation in the content and ease of production of the resin composition.

[0021] When producing the resin composition, it is preferable to blend an antioxidant for the purpose of suppressing thermal degradation of the resin composition during melt spinning, and suppressing thermal and light-induced degradation during thermoforming of the three-dimensional network structure. The amount of antioxidant added is preferably 0.05% by mass or more, more preferably 0.10% by mass or more, particularly preferably 0.20% by mass or more, and most preferably 0.50% by mass or more, based on 100% by mass of the resin composition. Examples of antioxidants include known phenol-based antioxidants, phosphorus-based antioxidants, and thioether-based antioxidants. Benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, NH-type hindered amine-based light stabilizers, and N-CH3-type hindered amine-based light stabilizers may also be used in combination. It is desirable to incorporate at least one of these additives.

[0022] 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), stearyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], Sumilizer G 80, and 2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mesitylene.

[0023] Phosphorus 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]dioxaphosphocin, tris(2,4-di-tert-butylphenyl) phosphite, tris(4-nonylphenyl) phosphite, 4,4'-Isopropylidenediphenol C12-15 alcohol phosphite, diphenyl(2-ethylhexyl) phosphite, diphenylisodecyl phosphite, and triisodecyl phosphite, triphenyl phosphite, and the like.

[0024] Examples of the thioether antioxidant include 2,2-bis[[3-(dodecylthio)-1-oxopropyloxy]methyl]-1,3-propanediyl bis[3-(dodecylthio)propionic acid] and ditridecyl 3,3'-thiobispropionate.

[0025] The resin composition may contain various additives in addition to antioxidants, ultraviolet absorbers, and light stabilizers depending on the purpose. Examples of additives that may be added include plasticizers such as phthalate esters, trimellitates, fatty acids, epoxies, adipic esters, and polyesters, antistatic agents, molecular weight modifiers such as peroxides, compounds having reactive groups such as epoxy compounds, isocyanates, and carbodiimide compounds, metal deactivators, organic and inorganic nucleating agents, neutralizing agents, antacids, antibacterial agents, fluorescent brighteners, fillers, flame retardants, flame retardant assistants, and organic and inorganic pigments.

[0026] The three-dimensional network structure of the present invention is a network structure in which a three-dimensional structure is formed by random loops consisting of continuous filaments of a polyester-based thermoplastic elastomer resin composition containing phosphate glass, which are joined in three dimensions.

[0027] The continuous filaments constituting the three-dimensional network structure of the present invention may be combined with other thermoplastic resins to form composite filaments, as long as the object of the present invention is not impaired. Examples of composite forms include composite filaments in which the filaments themselves are composited, such as sheath-core, side-by-side, and eccentric sheath-core types. In the case of sheath-core composite filaments, the phosphate glass may be contained in either the sheath or core component, or only in the sheath component.

[0028] The three-dimensional network structure of the present invention can be obtained based on known methods such as those described in Japanese Patent Application Laid-Open No. 7-68061. For example, a thermoplastic elastomer resin composition containing phosphate glass is dispensed into the nozzle orifices through a multi-row nozzle having multiple orifices, and continuous filaments are extruded downward from the nozzle at a spinning temperature 20°C to 120°C higher than the melting point of the resin composition. The continuous filaments are then contacted with each other in a molten state to fuse together and form a three-dimensional structure, while being sandwiched between a take-up conveyor net and cooled with cooling water in a cooling tank. The filaments are then drawn out, drained, or dried to obtain a three-dimensional network structure with smoothed surfaces on both or one side. To smooth only one side, the filaments are discharged onto an inclined take-up net, and are contacted with each other in a molten state to fuse together and form a three-dimensional structure, while only the surface of the take-up net is cooled while relaxing its shape. The resulting three-dimensional network structure can also be annealed. The drying of the three-dimensional network structure may also be referred to as annealing.

[0029] The cross-sectional shape of the continuous filaments that make up the three-dimensional network structure of the present invention is not particularly limited, but by making it a hollow cross-section or an irregular cross-section, it is possible to impart preferable compression resistance and feel. Alternatively, the three-dimensional network structure may have, in the thickness direction, a small fiber diameter fiber main region mainly made of fibers having a relatively small fiber diameter, a large fiber diameter fiber main region mainly made of fibers having a relatively large fiber diameter, and a mixed region located between the small fiber diameter fiber main region and the large fiber diameter fiber main region, in which small fiber diameter fibers and large fiber diameter fibers are mixed.

[0030] The three-dimensional network structure of the present invention can be processed into a molded article from the resin production process within the scope of not deteriorating performance, and at any stage of commercialization, it can be subjected to a treatment process in which a chemical agent is attached by immersion or the like to impart functions such as deodorizing, antibacterial, deodorizing, antifungal, coloring, fragrance, flame retardancy, moisture absorbing and releasing, etc.

[0031] The three-dimensional network structure of the present invention may be formed into a laminated structure as long as the object of the present invention is not impaired. Examples of laminated structures include a structure in which the front and back layers are formed of filaments with different finenesses, or a structure in which the front and back layers are formed of three-dimensional network structures with different apparent densities. Examples of multilayering methods include a method in which three-dimensional network structures are stacked on top of each other and fixed with a side fabric or the like, a method in which they are melt-bonded by heating, a method in which they are bonded with an adhesive, or a method in which they are restrained by sewing or a band or the like.

[0032] The three-dimensional network structure of the present invention has an excellent reduced viscosity retention rate after heat treatment. Here, when the viscosity of the polymer solution is η, the viscosity of the solvent is η, and the concentration of the solute polymer in the polymer solution is c, the reduced viscosity ηsp / c is given by the formula {(η-η0) / η0} / c. The reduced viscosity retention rate is a measure for relatively comparing the molecular weights of polymers.

[0033] For example, when the molecular weight of a polyester-based thermoplastic elastomer resin composition is reduced by hydrolysis, the reduced viscosity of the polyester-based thermoplastic elastomer resin composition after hydrolysis becomes smaller than the reduced viscosity of the polyester-based thermoplastic elastomer resin composition before hydrolysis. Therefore, resistance to hydrolysis caused by long-term exposure to moisture in the air can be evaluated by the change in reduced viscosity after an accelerated test. That is, the three-dimensional network structure is heat-treated in a high-temperature, high-humidity atmosphere, and the reduced viscosity of the resin composition constituting the three-dimensional network structure is compared before and after the treatment, thereby evaluating the hydrolysis resistance.

[0034] The reduced viscosity retention rate after heat treatment is expressed by the following formula (1), where A is the reduced viscosity of the resin composition constituting the three-dimensional network structure, and B is the reduced viscosity of the resin composition constituting the three-dimensional network structure after being heat treated for 240 hours in an atmosphere at a temperature of 80°C and a relative humidity of 90 RH%. Reduced viscosity retention rate after heat treatment = (B / A) × 100 (1)

[0035] The greater the retention of reduced viscosity after heat treatment, the smaller the decrease in molecular weight after heat treatment, i.e., the more excellent the hydrolysis resistance. In other words, in the present invention, the retention of reduced viscosity after heat treatment serves as an index for evaluating the hydrolysis resistance of the three-dimensional network structure. The three-dimensional network structure of the present invention preferably has a reduced viscosity retention rate of 65% or more after heat treatment. If the reduced viscosity retention rate after heat treatment is 65% or more, hydrolysis is unlikely to occur even when exposed to moisture in the air for a long period of time, that is, the structure has excellent hydrolysis resistance. From the viewpoint of hydrolysis resistance, the reduced viscosity retention rate after heat treatment is more preferably 70% or more, even more preferably 75% or more, particularly preferably 80% or more, and most preferably 85% or more.

[0036] The thickness of the three-dimensional network structure of the present invention is preferably 10 mm or more, more preferably 20 mm or more. If the thickness is less than 10 mm, a feeling of hitting the bottom may occur when used as a cushioning material. In consideration of the manufacturing equipment, the upper limit of the thickness is preferably 300 mm or less, more preferably 200 mm or less, and even more preferably 120 mm or less.

[0037] The apparent density of the three-dimensional network structure of the present invention is 0.005 g / cm 3 More than 0.20g / cm 3 Preferably less than 0.01 g / cm 3 More than 0.18g / cm 3 Less than 0.02 g / cm is more preferable. 3 More than 0.15g / cm 3 More preferably, the apparent density is 0.005 g / cm 3If the apparent density is less than 0.20 g / cm, the required hardness may not be maintained when used as a cushioning material. 3 If the temperature exceeds this range, the material may become too hard and may not be suitable as a cushioning material.

[0038] Regarding the fiber diameter of the continuous filaments constituting the three-dimensional network structure of the present invention, if the fiber diameter is small, the required hardness may not be ensured when used as a cushioning material. On the other hand, if the fiber diameter is too large, the cushion may become too hard depending on its intended use. Therefore, it is preferable to set the fiber diameter appropriately according to the intended use of the cushion. The fiber diameter is preferably 0.1 mm or more, more preferably 0.2 mm or more. If the fiber diameter is less than 0.1 mm, the denseness and soft feel are good, but it becomes difficult to ensure the required hardness for the network structure. On the other hand, the fiber diameter is preferably 3.0 mm or less, more preferably 2.5 mm or less. If the fiber diameter exceeds 3.0 mm, the three-dimensional network structure can be sufficiently hard, but the network structure may become coarse, and other cushioning properties may be inferior.

[0039] (effect) The three-dimensional network structure of the present invention has excellent hydrolysis resistance, is resistant to resin deterioration due to moisture in the air during long-term use, and has excellent durability during long-term use. [Example]

[0040] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Measurements and evaluations of property values ​​in the examples were carried out as follows.

[0041] (1) Reduced viscosity [Preparation of test solution] The pellets or three-dimensional network structure to be tested are placed in a hot air dryer set to an internal temperature of 70°C and left to dry for 25 minutes. The dried pellets or three-dimensional network structure are cut into small pieces so that the pellet or fiber length is within 2 mm, and 0.08 ± 0.003 g of sample is weighed. A phenol / 1,1,2,2-tetrachloroethane mixed solvent (60 / 40 by mass) is added to the obtained sample with an accuracy of ± 0.01 ml to obtain a solution with a concentration of 0.2 g / dL. The resulting solution is heated to 70°C and stirred for 30 minutes to dissolve the sample. The solution is then cooled in a water bath at 15 ± 1°C and left at room temperature to obtain the test solution. [Measurement of solvent outflow time t0 (blank test)] An AVL-2C capillary (Ubbelohde viscometer) automatic viscosity measuring device manufactured by Asahi Kasei Technosystems is used. The viscosity tube is an Ubbelohde type viscosity tube with a capillary diameter of 0.77 mm (±2%). The temperature of the thermostatic bath of the automatic viscosity measuring device and the test temperature are set to 30±0.1°C. A phenol / 1,1,2,2-tetrachloroethane mixed solvent (=60 / 40; mass / weight ratio) is placed in the viscosity tube. The viscosity tube is attached to the thermostatic bath and adjusted to a temperature of 30±0.1°C for 10 minutes. The test is then started, and the outflow time (seconds) of the mixed solvent is measured twice consecutively. The average of the two measurements is taken as the solvent outflow time t0 (seconds).

[0042] [Measurement of the outflow time t1 of the test solution] Use the same automatic viscosity measuring device as used to measure t0. Use the same viscosity tube as used to measure t0 (do not change the viscosity tube). Set the temperature of the thermostatic bath of the automatic viscosity measuring device and the test temperature to 30±0.1°C. Clean the viscosity tube with the test solution. Place the test solution into the viscosity tube. Attach the viscosity tube to the thermostatic bath and adjust the temperature to 30±0.1°C for 10 minutes. Then start the test and measure the outflow time (seconds) of the mixed solvent twice in succession. The average of the two measurements is the solvent outflow time t1 (seconds).

[0043] [Calculation of reduced viscosity] Calculate the reduced viscosity (dl / g) using the following formula: Reduced viscosity ηsp / c = (t1 / t0 - 1) / c t1: Outflow time of test solution (seconds), t0: Outflow time of solvent (seconds), c: Concentration of test solution (0.2 g / dL)

[0044] (2) Reduced viscosity retention rate after heat treatment A test piece measuring 5 cm x 5 cm x the thickness of the three-dimensional network structure is cut out from the three-dimensional network structure before heat treatment, placed in a moisture-proof and light-blocking bag, sealed, and stored at room temperature as test piece A before heat treatment. A test piece measuring 10 cm x 10 cm x the thickness of the three-dimensional network structure was cut out from the three-dimensional network structure, placed in a thermo-hygrostat with the temperature and relative humidity set to 80°C and 90%RH, and heat-treated for 240 hours. The test piece was then removed from the thermo-hygrostat and cooled at room temperature for 1 hour, resulting in test piece B after heat treatment. Using the above-mentioned (1) method for measuring reduced viscosity, the "reduced viscosity (reduced viscosity A) of the resin composition of the three-dimensional network structure before heat treatment" is measured from test piece A. Similarly, using the reduced viscosity measurement method (1) above, the "reduced viscosity (reduced viscosity B) of the resin composition of the three-dimensional network structure after heat treatment" is measured from test piece B. In this case, reduced viscosity A and reduced viscosity B are measured on the same day using the same automatic viscosity measurement device and the same viscosity tube. Next, the reduced viscosity retention rate after the heat treatment was calculated using the following formula. Reduced viscosity retention rate after heat treatment (%) = (B / A) x 100

[0045] (3) Phosphorus content in the three-dimensional network structure A 0.2 g sample was taken from the three-dimensional network structure, 10 ml of concentrated nitric acid was added, and wet acid decomposition was performed using a microwave decomposition device (Anton Paar Multiwave PRO). Specifically, the temperature was increased at 700 W for 10 minutes and then held at 700 W for 50 minutes to dissolve the sample. The sample was then cooled to 40 °C to obtain the sample solution. This sample solution was diluted to 50 ml with ultrapure water to prepare a pretreatment solution, which was then measured using a high-frequency inductively coupled plasma optical emission spectrometer (Hitachi High-Tech Science Corporation, SPECTROBLUE). The phosphorus concentration (mg / L) of the pretreatment solution was calculated using the previously prepared calibration curve and designated C (mg / L). Next, a blank test solution was prepared by diluting 10 ml of concentrated nitric acid to 50 ml with ultrapure water, which was then measured using the same device. The phosphorus concentration (mg / L) of the blank test solution was calculated using the previously prepared calibration curve and designated D (mg / L). Next, the phosphorus content (ppm; mass basis) in the three-dimensional network structure is calculated using the following formula. Phosphorus content in the three-dimensional network structure (ppm; mass basis) = (CD) x 50 / 0.2 The same procedure can be used to identify the contents of zinc, alkali metals, alkaline earth metals, etc. The silicon content is calculated using the following method (4).

[0046] (4) Silicon content in the three-dimensional network structure A 0.2 g sample was taken from the three-dimensional network structure, weighed into a platinum crucible, and pre-carbonized on a hot plate to 400 °C. This was followed by ashing at 550 °C for 8 hours using an electric furnace (Yamato Scientific, Model FO610). After ashing, 5 ml of a 5% aqueous sodium carbonate solution was added and heated on a hot plate until the water was completely evaporated. This was followed by alkali fusion treatment using a burner. Ultrapure water was added to the resulting white residue, which was then heated on a hot plate. After confirming complete dissolution of the salt, 5 ml of 6N hydrochloric acid was added and diluted to 25 ml with ultrapure water to create a pretreatment solution. This was then measured using a high-frequency inductively coupled plasma optical emission spectrometer (Hitachi High-Tech Science, SpectroBlue) to calculate the silicon concentration (mg / L) of the pretreatment solution, designated E (mg / L). Next, a blank test solution is prepared by adding 5 ml of 6N hydrochloric acid to 5 ml of 5% aqueous sodium carbonate solution and diluting the mixture to 25 ml with ultrapure water. This is then measured using the same device, and the silicon concentration (mg / l) of the blank test solution is calculated from the calibration curve prepared earlier and is designated as F (mg / l). Next, the silicon content (ppm; mass basis) in the three-dimensional network structure was calculated using the following formula. Silicon content in the three-dimensional network structure (ppm; mass basis) = (EF) x 25 / 0.2

[0047] (5) Melting point (Tm) Pellets of the thermoplastic elastomer were thinly sliced ​​and sealed in a test pan. A differential scanning calorimeter (TA Instruments, Q200) was used to measure the endothermic-heating curve at a heating rate of 20°C / min. The endothermic peak (melting peak) temperature at the time of crystalline melting was determined, and this was taken as the melting point of the thermoplastic elastomer.

[0048] (6) Acid value The acid value of the polyester-based thermoplastic elastomer was quantified by H-NMR measurement at a resonance frequency of 500 MHz using a proton-type nuclear magnetic resonance spectrometer (BRUKER, AVANCE-500 NMR device). The measurement solution was prepared as follows. <Measurement i> 10 to 20 mg of sample was dissolved in 0.12 ml of deuterated chloroform / hexafluoroisopropanol = 1 / 1 (volume ratio), and then 0.48 ml of deuterated chloroform was added and stirred thoroughly. The solution was then filled into an NMR tube and subjected to H-NMR measurement. <Measurement ii> After measurement i, 25 μL of a deuterated chloroform solution containing 0.2 mol / L triethylamine was added to the solution, and 1H-NMR measurements were performed again. Deuterated chloroform was used as the lock solvent, and the number of measurements was 128. <Acid value measurement> The acid value was determined as follows. When the chloroform peak was taken as 7.27 ppm, the peak at 8 ppm in Measurements I and II was terephthalic acid (a), the peak at 2 ppm was 1,4-butanediol (b), and the peak at 3.5 ppm was polytetramethylene glycol (c). The peak at 7.87 to 7.96 ppm in Measurement I was the satellite peak of terephthalic acid (d), and the peak at 7.87 to 7.96 ppm in Measurement II was the terephthalic acid terminal and satellite peak of terephthalic acid (e). The values ​​a to e in parentheses were taken as the integrals of each peak, and the acid value was calculated using the following formula: (f)=(a / 4×132)+(b / 4×88)+(c / 4×72) Acid value (eq / ton)=((ed) / 2×1000000) / (f) : Unit: meq / kg (mean value of n=2)

[0049] (7) Thickness and apparent density of the three-dimensional network structure Four test pieces measuring 10 cm x 10 cm x the thickness of the three-dimensional network structure were taken from the three-dimensional network structure. The test pieces were left at room temperature for 24 hours without load. The height (mm) of each test piece in the thickness direction was then measured using a thickness gauge (FD-80N, manufactured by Kobunshi Keiki). The average height of the four test pieces was taken as the thickness (mm) of the three-dimensional network structure. The weight W (g) of each test piece was measured using an electronic balance, and the apparent density (g / cm) of each test piece was calculated using the following formula: 3The average apparent density of the four test pieces was calculated as the apparent density (g / cm) of the three-dimensional network structure. 3 ) was decided. Apparent density (g / cm 3 ) = W / (10 × 10 × specimen height / 10)

[0050] (8) Fiber diameter of the three-dimensional network structure One test piece measuring 10 cm x 10 cm x the thickness of the three-dimensional network structure was taken from the three-dimensional network structure. From each test piece, ten filaments approximately 5 mm long were collected. The collected filaments were measured using an optical microscope with the appropriate magnification adjusted and the focus adjusted to the measurement point, and the fiber diameter was measured. The average of the values ​​from the ten points was taken as the fiber diameter (mm) of the three-dimensional network structure.

[0051] [Example 1] (1) Manufacture of polyester thermoplastic elastomers Dimethyl terephthalate (DMT), 1,4-butanediol (1,4-BD), and polytetramethylene glycol (PTMG: average molecular weight 1000) were charged as polyester thermoplastic elastomers along with a small amount of catalyst, and transesterification was carried out in a conventional manner. Polycondensation was then carried out while increasing the temperature under reduced pressure, and the mixture was pelletized to produce a polyester ester block copolymer elastomer. This production was carried out in a conventional manner, without using a method to reduce the thermal history between polymerization by polycondensation reaction and pelletization. The monomer composition, melting point, acid value and reduced viscosity of the resulting polyester-based thermoplastic elastomer (A-1) are shown in Table 1.

[0052] [Table 1]

[0053] (2) Production of a resin composition constituting a three-dimensional network fiber structure 99.495% by mass of the polyester-based thermoplastic elastomer (A-1), 0.005% by mass of phosphate glass fine powder (manufactured by Ishizuka Glass Co., Ltd., E74543), and 0.500% by mass of a phenol-based antioxidant were mixed together, and the mixture was melt-extruded in a twin-screw extruder, cooled, pelletized, and dried to obtain a resin composition that would serve as a raw material for the three-dimensional network fiber structure. The main composition of the phosphate glass used in the experiment is as follows: P2O5;37mol%, SiO2;7mol%, B2O3;12mol%, ZnO:35mol%, Al2O3;9mol%

[0054] (3) Manufacturing of three-dimensional network structures A nozzle was prepared with an effective nozzle surface measuring 1120 mm in width and 34.5 mm in thickness, and equipped with 5.0 mm outer diameter triple-bridge hollow-forming orifices arranged in a staggered pattern with a hole pitch of 8 mm. A resin composition was prepared by adding 0.005 mass% of the phosphate glass to a polyester-based thermoplastic elastomer (A-1) as the base resin, and extruded downward using the nozzle at a spinning temperature of 240°C and a single-hole extrusion rate of 1.5 g / min. The nozzle then passed through a cooling space at an ambient temperature of 25-35°C. Cooling water was placed 23 cm below the nozzle surface without blowing cooling air. A pair of 150 cm wide stainless steel endless net take-up conveyors were placed parallel to each other with openings 25 mm apart, partially above the water surface. The molten extruded filaments were twisted to form loops, and the contacting portions were fused to form a three-dimensional network structure. Both sides of the molten three-dimensional network structure were sandwiched between a take-up conveyor and pulled into cooling water at a speed of 0.9 m / min to solidify and flatten both sides. The structure was then cut to a predetermined size and subjected to a dry heat treatment with hot air at 105°C for 30 minutes to obtain a three-dimensional network structure. The properties of the obtained three-dimensional network structure are shown in Table 3. The obtained three-dimensional network structure had a reduced viscosity retention rate of 68% after heat treatment and was excellent in hydrolysis resistance.

[0055] During the melt extrusion, the following two methods for reducing the thermal history were not used. (a) Shear volume per discharge (Q / N, unit cm 3 / rev) is between 3 and 200 Q: What is the amount of resin discharged from the nozzle per minute (cm 3 / min) Screw rotation speed (rev / min) to produce N:Q (b) The transit time through the pipe (V / Q, unit: min) is 1 to 30 V: The total volume (cm) of the resin that is melted and extruded by the extruder, passes through the piping, and is discharged from the nozzle. 3 ) Q: What is the amount of resin discharged from the nozzle per minute (cm 3 / min)

[0056] [Example 2] A mixture of 99.49% by mass of the polyester-based thermoplastic elastomer (A-1), 0.01% by mass of the same phosphate glass fine powder as in Example 1, and 0.50% by mass of a phenol-based antioxidant was prepared. The mixture was then melt-extruded in a twin-screw extruder, cooled, pelletized, and dried to obtain a resin composition having a three-dimensional network fiber structure. The resulting resin composition was used to obtain a three-dimensional network structure in the same manner as in Example 1. The properties of the obtained three-dimensional network structure are shown in Table 3. The obtained three-dimensional network structure had a reduced viscosity retention rate of 70% after heat treatment and was excellent in hydrolysis resistance.

[0057] [Example 3] 99.45% by mass of the above polyester-based thermoplastic elastomer (A-1) was mixed with 0.05% by mass of the same phosphate glass fine powder and 0.50% by mass of a phenol-based antioxidant as in Example 1. The mixture was then melt-extruded in a twin-screw extruder, cooled, pelletized, and dried to obtain a resin composition having a three-dimensional network fiber structure. The resulting resin composition was used to obtain a three-dimensional network structure in the same manner as in Example 1. The properties of the obtained three-dimensional network structure are shown in Table 3. The obtained three-dimensional network structure had a reduced viscosity retention rate of 74% after heat treatment and was excellent in hydrolysis resistance.

[0058] [Example 4] 99.4% by mass of the above polyester-based thermoplastic elastomer (A-) was mixed with 0.1% by mass of the same phosphate glass fine powder and 0.5% by mass of a phenol-based antioxidant as in Example 1. The mixture was then melt-extruded using a twin-screw extruder, cooled, pelletized, and dried to obtain a resin composition having a three-dimensional network fiber structure. The resulting resin composition was used to obtain a three-dimensional network structure in the same manner as in Example 1. The properties of the obtained three-dimensional network structure are shown in Table 3. The obtained three-dimensional network structure had a reduced viscosity retention rate of 76% after heat treatment and was excellent in hydrolysis resistance.

[0059] [Example 5] 99.0% by mass of the above polyester-based thermoplastic elastomer (A-1) was mixed with 0.5% by mass of the same phosphate glass fine powder and 0.5% by mass of a phenol-based antioxidant as in Example 1. The mixture was melt-extruded using a twin-screw extruder, cooled, pelletized, and dried to obtain a resin composition having a three-dimensional network fiber structure. The resulting resin composition was used to obtain a three-dimensional network structure in the same manner as in Example 1. The properties of the obtained three-dimensional network structure are shown in Table 3. The obtained three-dimensional network structure had a reduced viscosity retention rate of 82% after heat treatment and was excellent in hydrolysis resistance.

[0060] [Example 6] 98.5% by mass of the above polyester-based thermoplastic elastomer (A-1) was mixed with 1.0% by mass of the same phosphate glass fine powder and 0.5% by mass of a phenol-based antioxidant as in Example 1. The mixture was melt-extruded using a twin-screw extruder, cooled, pelletized, and dried to obtain a resin composition having a three-dimensional network fiber structure. The resulting resin composition was used to obtain a three-dimensional network structure in the same manner as in Example 1. The properties of the obtained three-dimensional network structure are shown in Table 3. The obtained three-dimensional network structure had a reduced viscosity retention rate of 86% after heat treatment and was excellent in hydrolysis resistance.

[0061] [Example 7] 99.4% by mass of the above polyester-based thermoplastic elastomer (A-1) was mixed with 0.1% by mass of the same phosphate glass fine powder and 0.5% by mass of a phenol-based antioxidant as in Example 1. The mixture was melt-extruded using a twin-screw extruder, cooled, pelletized, and dried to obtain a resin composition having a three-dimensional network fiber structure. Using the obtained resin composition, a three-dimensional network structure was obtained in the same manner as in Example 1. The properties of the obtained three-dimensional network structure are shown in Table 3. The obtained three-dimensional network structure had a reduced viscosity retention rate of 75% after heat treatment and was excellent in hydrolysis resistance.

[0062] [Comparative Example 1] 99.5% by mass of the polyester-based thermoplastic elastomer (A-1) was mixed with 0.5% by mass of a phenol-based antioxidant, and the mixture was then melt-extruded in a twin-screw extruder, cooled, pelletized, and dried to obtain a resin composition having a three-dimensional network fiber structure. The obtained resin composition was treated in the same manner as in Example 1 to obtain a three-dimensional network structure. The properties of the obtained three-dimensional network structure are shown in Table 3. Because the obtained three-dimensional network structure did not contain phosphate glass, the reduced viscosity retention rate after heat treatment was 62%, and the hydrolysis resistance was poor.

[0063] Comparative Example 2 (1) Manufacturing of thermoplastic elastomers Dimethyl terephthalate (DMT) and 1,4-butanediol (1,4-BD) were charged as a polyester thermoplastic elastomer with a small amount of catalyst. After transesterification using conventional methods, polytetramethylene glycol (PTMG) was added and polycondensed while increasing the temperature and reducing the pressure to produce a polyester ester block copolymer elastomer. Next, using a conventional method to reduce the thermal history after polymerization, 1% by mass of a phenolic antioxidant was added and mixed and kneaded. The mixture was then pelletized and vacuum dried at 50°C for 48 hours to obtain thermoplastic elastomer (A-2). The monomer composition, melting point, acid value, and reduced viscosity of the polyester-based thermoplastic elastomer (A-2) are shown in Table 2. The polyester-based thermoplastic elastomer (A-2) had a lower acid value than the polyester-based thermoplastic elastomer (A-1).

[0064] [Table 2]

[0065] (2) Manufacturing of three-dimensional network structures A nozzle was prepared with an effective nozzle surface of 1120 mm in the width direction and 64 mm in the thickness direction, in which orifices with an outer diameter of 5.0 mm and a triple-bridge hollow-forming cross-section were arranged in a staggered pattern with a hole pitch of 8 mm. In Comparative Example 2, the method described in Example 1 for reducing the thermal history during melt extrusion during spinning was used. The polyester thermoplastic elastomer resin composition was extruded downward from the nozzle at a melt temperature of 240°C and a single-hole extrusion rate (Q) of 3.2 g / min under the following conditions: screw rotation speed (N) of 70 rpm, shear amount per extrusion (Q / N) of 48.7 cm 3 The flow rate was 1 / rev, and the time it took to pass through the pipe was 1 minute. Cooling water was placed 33 cm below the nozzle surface. A pair of take-up conveyors was arranged with 150 cm wide stainless steel endless nets in parallel with openings 50 mm apart, with some of the netting exposed above the water surface. The molten extruded filaments were wound onto the conveyor net above the water surface to form loops, and the contacting parts were fused together to form a three-dimensional network structure. Both sides of the molten network structure were sandwiched between the take-up conveyors and pulled into cooling water at a speed of 2.0 m / min, where it solidified to flatten both sides in the thickness direction. The structure was then cut to a specified size and subjected to a dry heat treatment with 110°C hot air for 15 minutes to obtain a three-dimensional network structure. The properties of the obtained three-dimensional network structure made of a polyester-based thermoplastic elastic resin are shown in Table 3. The obtained three-dimensional network structure had a reduced viscosity retention rate of 62% after heat treatment and was poor in hydrolysis resistance.

[0066] [Table 3] [Industrial Applicability]

[0067] The three-dimensional network structure of the present invention has excellent hydrolysis resistance and is unlikely to deteriorate due to moisture in the air even when used for long periods of time, and is therefore suitable for long-term use as cushioning materials used in office chairs, furniture, sofas, bedding such as beds, vehicle seats for trains, automobiles, motorcycles, child seats, strollers, etc., floor mats, and shock-absorbing mats such as collision and pinch prevention members, etc.

Claims

1. A three-dimensional network structure made of a polyester-based thermoplastic elastomer resin composition and having a three-dimensional random loop bonded structure composed of continuous filaments, the resin composition contains phosphate glass, The three-dimensional network structure has a molar ratio of phosphorus atoms to silicon atoms (P / Si) in the phosphate glass of 1 to 15.

2. The phosphate glass is P ２ O ５ , SiO ２、 and ZnO, and further containing at least one selected from the group consisting of alkali metal oxides and alkaline earth metals.

3. The three-dimensional network structure according to claim 2 , wherein the phosphate glass contains an alkaline earth metal oxide containing the alkaline earth metal.

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