TW202302018A - Biodegradable three-dimensional network structure - Google Patents

Abstract

Provided is a biodegradable three-dimensional network structure having excellent compression durability, and compression recovery after heat compression. The biodegradable three-dimensional network structure is characterized by having an apparent density of 0.005g/cm3-0.30 g/cm3 and a thickness of 10-100 mm, and including a linear fiber, wherein the linear fiber has a fiber diameter of 0.2-2.0 mm and includes a polybutylene adipate terephthalate-based resin having a crystal melting enthalpy of at least 16 J/g, and a weight average molecular weight of at least 35,000.

Description

Biodegradable three-dimensional network structure

The invention relates to a biodegradable three-dimensional network structure.

So far, various biodegradable three-dimensional network structures are known. For example, in Patent Document 1, a biodegradable aquatic plant support body for greening is disclosed, which is composed of a three-dimensional network. The three-dimensional network has three-dimensional random rings. The three-dimensional random rings have biodegradable thermoplastic properties. A plurality of meandering continuous linear bodies of resin are joined at least in part. Patent Document 2 discloses a three-dimensional network fibrous material aggregate, which is biodegradable and is composed of a variety of fibrous materials that are partially bonded to each other. The fibrous material at least contains a biodegradable resin, and Partial bonding of bonding facilitates the composition of the resin. In addition, in Patent Document 3, a biodegradable three-dimensional structure is disclosed, which has a fineness of 300 deniers to 100,000 deniers and is mainly composed of thermoplastic polylactic acid resin. joined together. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-32236. [Patent Document 2] Japanese Patent Laid-Open No. 2020-128608. [Patent Document 3] Japanese Patent Laid-Open No. 2000-328422

[Problem to be Solved by the Invention]

Patent Document 1 discloses a technique for improving the plant retention of a biodegradable network structure. In addition, Patent Document 2 discloses a technique for enhancing partial joining of fiber materials of a biodegradable network structure. In addition, Patent Document 3 discloses a technique for distributing stress by forming a helical spring-shaped or ring-shaped portion in a biodegradable three-dimensional structure, and deforming the portion appropriately in response to compressive stress. In this way, various attempts have been made to enhance the function of biodegradable network structures, but no biodegradable network materials with excellent compression durability and compression recovery after heating and compression have been known. structure. The present invention was made in view of the above circumstances, and an object of the present invention is to provide a biodegradable three-dimensional network structure excellent in compression durability and compression recovery after heating and compression. [Means to solve the problem]

The biodegradable three-dimensional network structure of the embodiment of the present invention is as follows. [1] A biodegradable three-dimensional network structure, characterized in that: the apparent density is 0.005g/cm ³ to 0.30g/cm ³ ; the thickness is 10mm to 100mm; The fiber diameter is 0.2 mm to 2.0 mm, the crystalline melting enthalpy is more than 16 J/g, and contains polybutylene adipate terephthalate resin with a weight average molecular weight of more than 35,000.

With the above configuration, compression durability and compression recovery after heating and compression can be improved. A preferred aspect of the biodegradable three-dimensional network structure is as follows. [2] The biodegradable three-dimensional network structure as described in [1], wherein the linear fibers form a three-dimensional random ring structure. [3] The biodegradable three-dimensional network structure according to [1] or [2], wherein the melting enthalpy of the crystals is 30 J/g or less. [4] The biodegradable three-dimensional network structure described in any one of [1] to [3] is used for a cushion. [5] The biodegradable three-dimensional network structure described in any one of [1] to [4], wherein the polybutylene adipate terephthalate-based resin has a weight average molecular weight of 150,000 or less . [6] The biodegradable three-dimensional network structure according to any one of [1] to [5], wherein the linear fibers have a melting point of 100°C or higher and 120°C or lower. [7] The biodegradable three-dimensional network structure according to any one of [1] to [6], wherein the linear fibers have a hollow cross-sectional shape. [8] The biodegradable three-dimensional network structure described in [7], wherein the hollow rate of the linear fibers is not less than 1% and not more than 30%. [9] The biodegradable three-dimensional network structure as described in [7], wherein the hollow rate of the linear fibers is not less than 2% and not more than 25%. [10] The biodegradable three-dimensional network structure according to any one of [1] to [9], wherein the melting enthalpy of the crystal is 17 J/g or more. [11] The biodegradable three-dimensional network structure according to any one of [1] to [10], wherein the melting enthalpy of the crystals is 28 J/g or less. [12] The biodegradable three-dimensional network structure according to any one of [1] to [11], wherein the polybutylene adipate terephthalate-based resin has a weight average molecular weight of 37,000 or more . [13] The biodegradable three-dimensional network structure according to any one of [1] to [12], wherein the polybutylene adipate terephthalate-based resin has a weight average molecular weight of 120,000 or less . [Efficacy of the invention]

According to the present invention, with the above configuration, it is possible to provide a biodegradable three-dimensional network structure excellent in compression durability and compression recovery after heating and compression.

The biodegradable three-dimensional network structure according to the embodiment of the present invention has an apparent density of 0.005 g/cm ³ to 0.30 g/cm ³ , a thickness of 10 mm to 100 mm, and includes linear fibers. The fiber diameter of the aforementioned linear fibers 0.2mm to 2.0mm, crystal fusion enthalpy of 16J/g or more, and polybutylene adipate terephthalate resin with a weight average molecular weight of 35,000 or more. With the above configuration, compression durability and compression recovery after heating and compression can be improved. Each configuration will be described in detail below.

The apparent density of the three-dimensional network structure is 0.005g/cm ³ to 0.30g/cm ³ . With the apparent density being above 0.005 g/cm ³ , the hardness of the three-dimensional network structure is improved. As a result, when the three-dimensional network structure is used for a cushion pad or the like, the bottoming feeling can be reduced. Therefore, the apparent density is preferably at least 0.01 g/cm ³ , more preferably at least 0.02 g/cm ³ , still more preferably at least 0.03 g/cm ³ , and still more preferably at least 0.05 g/cm ³ . On the other hand, when the apparent density is 0.30 g/cm ³ or less, the flexibility is improved, and it can be used more suitably as a cushioning material or the like. Therefore, the apparent density is preferably at most 0.20 g/cm ³ , more preferably at most 0.15 g/cm ³ . The apparent density of the three-dimensional network structure can be measured by the method described in the examples below.

The thickness of the three-dimensional network structure is 10mm to 100mm. With a thickness of 10 mm or more, it is easy to use the three-dimensional network structure as a cushioning material or the like. The thickness is preferably at least 15 mm, more preferably at least 20 mm, further preferably at least 22 mm. On the other hand, considering the size of the manufacturing device, the thickness is 100 mm or less, preferably 90 mm or less, more preferably 80 mm or less, and still more preferably 50 mm or less. The thickness of the three-dimensional network structure can be measured by the method described in the examples below.

The three-dimensional network structure contains linear fibers. The linear fiber preferably has a three-dimensional random ring structure. In addition, the linear fiber is preferably a continuous linear body. The term "continuous linear body" refers to a linear filament having a continuous portion of at least 5mm or more. It becomes easy to form a three-dimensional network structure at the site formed by the intersection of the continuous linear body. Therefore, it is preferable that the three-dimensional network structure has a bonding portion where the intersecting portions of the linear fibers are connected to each other.

The linear fiber can be a composite linear body such as a sheath-core type, a side-by-side type, and an eccentric sheath-core type. The composite linear body may be a composite linear body in which polybutylene adipate terephthalate-based resin and other thermoplastic resins are combined. The cross-sectional shape of the linear fiber may be either a hollow cross-section or a solid cross-section, but a hollow cross-section is preferable because it can reduce weight. In addition, since the cross-sectional shape of the linear fiber is a hollow cross-section, the compression recovery after heating and compression is improved. In addition, the cross-sectional shape of the linear fiber is preferably a profiled cross-section. Thereby, suitable hardness and cushioning properties can be easily imparted to the three-dimensional network structure. The hollow rate of the linear fibers is preferably at least 1%, more preferably at least 2%, more preferably at least 5%, and more preferably at most 30%, more preferably at most 25%, even more preferably at most 20%. . The hollow ratio of the linear fibers can be measured by the method described in the examples described later.

The fiber diameter of the linear fibers is 0.2 mm to 2.0 mm. The hardness is improved by making the fiber diameter more than 0.2mm. Therefore, the fiber diameter is preferably at least 0.3 mm, more preferably at least 0.4 mm. On the other hand, when the fiber diameter is 2.0 mm or less, the denseness of the network structure can be improved, cushioning properties can be improved, and the touch of the network structure can be easily softened. Therefore, the fiber diameter is preferably 1.7 mm or less, more preferably 1.5 mm or less, further preferably 1.2 mm or less. The fiber diameter of a linear fiber can be measured by the method described in the Example mentioned later. The shape of the profile of the cross section of the linear fiber may be circular, elliptical, polygonal, or rounded polygonal. The fiber diameter of the fiber whose contour is not circular corresponds to the longest distance between any two points on the contour of the fiber.

The melt flow rate (MFR) of the linear fibers is preferably 3 g/10 minutes to 60 g/10 minutes. When MFR is 3 g/10 minutes or more, it becomes easy to raise a melt viscosity, and it becomes possible to increase the fiber diameter of a linear fiber. The MFR is more preferably at least 4 g/10 minutes, further preferably at least 6 g/10 minutes, still more preferably at least 8 g/10 minutes, particularly preferably at least 10 g/10 minutes. On the other hand, if MFR is 60 g/10 minutes or less, the compression recovery property after heating and compression can be improved easily. The MFR is more preferably at most 50 g/10 minutes, further preferably at most 40 g/10 minutes, still more preferably at most 30 g/10 minutes, particularly preferably at most 25 g/10 minutes. The MFR of a linear fiber can be measured by the method described in the Example mentioned later.

In the case of using a commercially available resin as the polybutylene adipate terephthalate-based resin constituting the linear fibers, when the melt flow rate (MFR) of the resin is low, water is added to the resin and the resin is melt-extruded. The resin is hydrolyzed when it comes out, so that the MFR of the resin can be increased. Thereby, the MFR of a linear fiber can be raised. On the other hand, when the MFR of the resin is high, the MFR of the resin can be reduced by drying the resin and then performing melt extrusion. Thereby, the MFR of a linear fiber can be reduced.

The crystal fusion enthalpy of the linear fiber is 16 J/g or more. When the enthalpy of crystal fusion is 16 J/g or more, the compression durability of the three-dimensional network structure and the compression recovery after heating and compression can be improved. The crystal melting enthalpy is preferably at least 17 J/g, more preferably at least 18 J/g, still more preferably at least 19 J/g, still more preferably at least 20 J/g, particularly preferably at least 21 J/g. On the other hand, the crystal fusion enthalpy is preferably 30 J/g or less. Thereby, the flexibility of the three-dimensional network structure is improved, and noise generated during compression and recovery can be reduced. The crystal fusion enthalpy is more preferably at most 28 J/g, further preferably at most 26 J/g.

The crystalline melting enthalpy (J/g) of the linear fiber can be obtained from the integral value of the endothermic peak (melting peak) of the endothermic exothermic curve. Calorimeter, measured under a nitrogen atmosphere at a heating rate of 20°C/min. The integral value can be obtained by the following method: the point where the curve of the endothermic peak (melting peak) separates from the reference line on the low temperature side is set as the starting point, and the point where the curve begins to contact the high temperature side reference line is set as the end point, Draw a straight line connecting the starting point and the ending point, and integrate the part surrounded by the straight line and the curve. An example of endothermic and exothermic curves is shown in Fig. 1 . The dotted line in Fig. 1 is a straight line connecting the above-mentioned start point and end point of the endothermic peak (melting peak), and the part surrounded by the dotted line and the curved line is the integration area for integration.

In the case of using a commercially available resin as the polybutylene adipate terephthalate-based resin constituting the linear fibers, if the melting enthalpy of the crystal is lower than the desired range, annealing is performed as described later to melt the crystal. The enthalpy is controlled to the desired range.

Polybutylene adipate terephthalate resin is a biodegradable resin, a copolymer of adipic acid, terephthalic acid, and butanediol. It is expected that the polybutylene adipate terephthalate resin is a biodegradable resin, which will become a solution to the problem of waste disposal and microplastics. Adipic acid, terephthalic acid, and butanediol do not need to be copolymerized at the same time, but can also be copolymerized in multiple stages. In addition, the polybutylene adipate terephthalate resin is preferably a thermoplastic resin.

When synthesizing polybutylene adipate terephthalate resin, in addition to adipic acid, terephthalic acid, and butanediol, trace amounts of other copolymerization components can also be added. As other copolymerization components, other dicarboxylic acids other than terephthalic acid and adipic acid, modifiers for the purpose of chain extension, terminal capping, etc., etc. may be mentioned. These other copolymerization components can be used individually or in combination of 2 or more types.

As another dicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, etc. are mentioned. These other dicarboxylic acids can be used individually or in combination of 2 or more types.

As a modifier, a polyisocyanate compound, a diol compound, etc. are mentioned. As a polyisocyanate compound, a diisocyanate compound is mentioned. Examples of diisocyanate compounds include hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylene diisocyanate, carbodiimide modified MDI (diphenylmethane diisocyanate; diphenylmethane diisocyanate), polymethylene polyphenyl polyisocyanate, etc. These polyisocyanate compounds can be used individually or in combination of 2 or more types. As the diol compound, other diols and polyalkylene glycols other than butanediol may, for example, be mentioned. Examples of other diols include methylene glycol, ethylene glycol, propylene glycol, pentanediol, hexylene glycol and the like. The polyalkylene glycol may, for example, be polymethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol (polytetramethylene glycol), or the like. These diol compounds can be used individually or in combination of 2 or more types.

Examples of polybutylene adipate terephthalate-based resins include organisms listed in the positive list (positive list) of GreenPla (biodegradable plastic) classification number A-1 of the Japan Bioplastics Association. Decomposing synthetic polymer compounds. Specifically, Ecoflex (registered trademark) manufactured by BASF Japan Co., Ltd., Eastar Bio, GP, Eastar Bio, Ultra manufactured by GSI Creos Co., Ltd. (Novamont Corporation), A400 (ECOPOND) manufactured by KINGFA Co., Ltd. KD 1024), TUNHE PBAT TH-801T manufactured by XINJIANG BLUE RIDGE TUNHE CHEMICAL INDUSTRY JOINT STOCK company. These polybutylene adipate terephthalate resins can be used alone or in combination of two or more.

The polybutylene adipate terephthalate-based resin has a weight average molecular weight (g/mol) of 35,000 or more. Thereby, the compression recovery property after heating and compression can be improved. The weight average molecular weight is preferably at least 37,000, more preferably at least 40,000. On the other hand, flexibility can be improved by weight average molecular weight being 150000 or less. The weight average molecular weight is preferably 150,000 or less. Moreover, polymer melt viscosity can be made low by weight average molecular weight being 120000 or less. The weight average molecular weight is more preferably at most 120,000. Moreover, it is also preferable that the weight average molecular weight (g/mol) of the resin which comprises a linear fiber exists in this range. The weight average molecular weight can be determined by gel permeation chromatography (GPC; Gel Permeation Chromatography) or the like.

The linear fibers may contain other biodegradable resins other than polybutylene adipate terephthalate resin. As other biodegradable resins, polylactic acid, polylactic acid/polycaprolactone copolymer, polylactic acid/polyether copolymer, polyethylene terephthalate succinate, polybutylene succinate are preferable , polybutylene succinate adipate, polyglycolic acid, polycaprolactone, polyvinyl alcohol, cellulose acetate, etc. These other biodegradable resins can be used alone or in combination of two or more. For details of these other biodegradable resins, please refer to the positive list of GreenPla (biodegradable plastic) classification number A-1 of the Japan Bioplastic Association. The linear fibers may contain resins other than biodegradable resins. As this resin, thermoplastic resins, such as polyurethane and polyester, are mentioned.

As a monomer for synthesizing the resin constituting the linear fibers, a petroleum-derived monomer can be used, but it is preferable to use a biomass-derived monomer because it can reduce environmental load. For monomers derived from biomass, for example, refer to the monomers listed in the positive list of classification code A (bioplastics) of the Japan Bioplastics Association.

The total content of the adipic acid component, terephthalic acid component, and butanediol component is preferably 70 mol% in 100 mol% of all components constituting the polybutylene adipate terephthalate-based resin. % or more, more preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, especially preferably 99 mol% or more.

The linear fibers may also contain deodorants, antibacterial agents, antimold agents, antimite agents, deodorants, antimold agents, fragrances, flame retardants, moisture absorbing and dehumidifying agents, antioxidants, lubricants, and the like. These additives can be used individually or in combination of 2 or more types.

The content of the polybutylene adipate terephthalate-based resin in 100% by mass of the linear fibers is preferably at least 50% by mass, more preferably at least 60% by mass, further preferably at least 80% by mass, and still more preferably at least 80% by mass. Preferably it is at least 90% by mass, more preferably at least 95% by mass, most preferably at least 98% by mass. In addition, the linear fibers may also be composed of polybutylene adipate terephthalate resin.

The linear fibers preferably have a melting point of not less than 100°C and not more than 120°C. Thereby, the compression recovery property of the three-dimensional network structure after heating and compression can be easily improved. The melting point is more preferably at most 115°C. By performing the annealing treatment described later, the melting point of the polybutylene adipate terephthalate-based resin is lowered, and as a result, the melting point of the linear fiber can be easily lowered to 120° C. or lower.

The three-dimensional network structure may also have a multilayer structure. As a multi-layer structure, the structure of the surface layer and the inner layer is composed of linear fibers of different deniers, the structure of the surface layer and the inner layer is formed of structures with different apparent densities, and long-fiber non-woven fabrics or short-fiber non-woven fabrics are laminated and multi-layered. structure etc. As a multilayering method, a method of melting and solidifying by heating, a method of bonding with an adhesive, and a method of binding by sewing or a band, etc. may be mentioned.

The shape of the three-dimensional network structure is not particularly limited, and examples thereof include plate shapes, polyhedrons such as triangular prisms and square prisms, cylinders, spheres, combinations of these shapes, and the like. When the three-dimensional network structure is formed, it can be formed by using a control board during the melt extrusion of the resin, or by cutting, hot pressing, and the like.

The three-dimensional network structure preferably has a compression residual strain of 30% or less at 70°C. Thereby, the compression recovery property after heating and compression can be improved. More preferably, it is 25% or less, More preferably, it is 23% or less. In addition, the 70°C compression residual strain may be 1% or more, and may be 5% or more. The 70°C compression residual strain can be measured by the method described in the examples described later.

The hardness of the three-dimensional network structure at 25% compression is preferably not less than 5.0N/φ50mm and not more than 100N/φ50mm. By being 5.0N/φ50mm or more, it is possible to reduce the bottoming feeling when the three-dimensional network structure is used for a cushioning material or the like. Therefore, it is more preferably 5.4 N/φ50 mm or more, further preferably 6.0 N/φ50 mm or more, and still more preferably 7.0 N/φ50 mm or more. On the other hand, cushioning property can be improved by being 100N/φ50mm or less. Therefore, it is more preferably 80 N/φ50 mm or less, further preferably 60 N/φ50 mm or less, still more preferably 30 N/φ50 mm or less. The hardness at 25% compression can be measured by the method described in the examples below.

The three-dimensional network structure preferably does not contain an attachment promoter. This can easily prevent excessive hardening due to excessive bonding in the three-dimensional network structure caused by the bonding accelerator. In addition, it is possible to easily prevent the decrease in the density of the three-dimensional network structure that is caused by excessively increasing the bonding range per contact point. As the adhesion-promoting resin, polycaprolactone, polybutylene succinate, polybutylene sebacate terephthalate, polybutylene azelaate terephthalate, and the like may, for example, be mentioned.

The three-dimensional network structure can also be colored. Coloring agents such as pigments and dyes can be used for coloring. The coloring agent may be contained in the resin before melt spinning, and the coloring agent may be coated on the linear fibers by dipping or coating after the three-dimensional network structure is formed.

The three-dimensional network structure is preferably used for cushioning. The cushion pad may support an object and have elasticity, or may be used to reduce impact. Examples of cushioning pads include: cushioning pads for bedding such as office chairs, furniture, sofas, and beds; cushioning pads for seats in vehicles such as trains, automobiles, two-wheeled vehicles, child safety chairs, and baby carriages; floor mats or anti-collision pads / Cushion pads such as impact-absorbing pads for anti-pinch components.

The three-dimensional network structure can be formed by the following method, for example. First, distribute polybutylene adipate terephthalate resin to the orifices of the nozzles from multiple rows of nozzles with multiple orifices. °C)) at the spinning temperature, it is ejected towards the lower side than the nozzle. Next, the continuous linear bodies are brought into contact with each other in a molten state and welded to form a three-dimensional network structure, while being clamped by a traction conveying net, and cooled by cooling water in a cooling tank. The distance between the nozzle surface and the cooling water surface is preferably at least 15 cm, more preferably at least 20 cm. Thereby, the hollow ratio of the fiber and the compactness of the network structure can be improved. On the other hand, the distance is preferably 40 cm or less, more preferably 35 cm or less. Thereby, a three-dimensional network structure having an appropriate apparent density and fiber diameter can be easily obtained. After cooling, extract the solidified three-dimensional network structure, drain off the water or dry it to obtain a three-dimensional network structure with smooth double or single surfaces. Regarding these spinning and cooling steps, the description in JP-A-7-68061 can be referred to. In the case of smoothing only one side, the continuous linear body may be ejected onto a slanted drag net, and brought into contact with each other in a molten state to be welded. At this time, it is only necessary to cool while relaxing the form of the pulled mesh surface while forming a three-dimensional network structure. Annealing is performed on the obtained three-dimensional network structure. Furthermore, the drying treatment of the three-dimensional network structure may also be used as the annealing treatment.

It is preferable to add water to the resin before spraying from the nozzle. The amount of water added is preferably 0.005% by mass or more relative to 100% by mass of the solid content of the resin. Thereby, the decomposition of the resin in the manufacturing step of the three-dimensional network structure can be accelerated, and the flexibility of the resin can be improved. On the other hand, the added amount of water is preferably 2.0% by mass or less. Thereby, excessive decomposition of the resin in the manufacturing process of the three-dimensional network structure can be prevented, and the compression recovery property after heating and compression can be improved easily. The amount of water added is more preferably at most 1.0 mass %, further preferably at most 0.5 mass %, still more preferably at most 0.2 mass %. In addition, the method of adding water to the resin is not particularly limited. For example, before the resin is sprayed from the nozzle, the resin is vacuum-dried at 100°C for more than 12 hours to make it absolutely dry. %, just add a predetermined amount of pure water.

The melt flow rate (MFR) of the polybutylene adipate terephthalate-based resin is preferably at the point before melt extrusion, and is less than the MFR of the desired three-dimensional network structure by 0.5 or more to less than 20.0 . Since thermal deterioration or shear deterioration of the resin is induced during melt extrusion, by controlling the MFR before melt extrusion as described above, it becomes easy to obtain a three-dimensional network structure having a desired MFR.

The polybutylene adipate terephthalate-based resin is preferably cooled with cooling water after melt molding. Polybutylene adipate terephthalate-based resins may shrink in molding until they are cooled and solidified. Therefore, it is only necessary to form a three-dimensional network structure with a width and thickness in consideration of molding shrinkage, but by lowering the melting and solidification temperature, molding shrinkage can be reduced. Therefore, the water temperature of the cooling water is preferably below 20°C, more preferably below 15°C. In addition, the cooling time by cooling water is preferably 30 seconds or more. The cooling and solidification is preferably carried out in a water tank.

Annealing can be carried out using a commercially available hot air drying furnace, or in a warm water bath. The annealing temperature is above 70°C. Thereby, the enthalpy of crystal fusion can be increased. Preferably it is 75°C or higher, more preferably 80°C or higher. On the other hand, the annealing temperature is 105°C or lower. This also increases the enthalpy of crystallization fusion.

The annealing time is preferably 1 minute or longer. Thereby, the enthalpy of crystal fusion can be increased. The annealing time is more preferably at least 5 minutes, further preferably at least 10 minutes, and still more preferably at least 15 minutes. On the other hand, the annealing time is preferably 60 minutes or less. Thereby, yellowing, odor, molecular weight reduction, etc. of the polybutylene adipate terephthalate-based resin accompanying decomposition or deterioration of the polymer during annealing can be reduced. Furthermore, productivity can also be improved. The annealing time is more preferably 50 minutes or less.

It is preferable to keep the temperature at 20° C. to 50° C. for more than 1 minute after cooling and solidification and before annealing. During the annealing process, the thickness may change due to its own weight, but by keeping the temperature at 20°C to 50°C after cooling and solidification, the change in thickness due to annealing can be reduced. For example, after cooling and solidifying in a water bath, the temperature in the first half of the oven may be lowered and maintained using a continuous dryer, and the temperature in the second half of the oven may be increased for annealing.

The water content of the three-dimensional network structure before annealing is preferably 15% or less. Thereby, decomposition of resin etc. can be reduced. The water content is more preferably at most 12%, and further preferably at most 10%. This water content is calculated by the following formula. The mass after vacuum-drying in the formula was defined as the mass after vacuum-drying at 90° C. for 2 hours. The water content of the three-dimensional network structure (%)={(the quality of the three-dimensional network structure before vacuum drying)-(the quality of the three-dimensional network structure after vacuum drying)}/(the three-dimensional network structure before vacuum drying Mass of structure)×100

It is also possible to impart deodorizing and antibacterial properties, anti-mold properties, anti-mite properties, deodorizing properties, anti-mold properties, aromatic properties, and flame retardancy to the resin at any stage from the manufacturing process to the molding process of the resin of the three-dimensional network structure. Sex, moisture absorption and dehumidification and other functions. In addition, when producing a three-dimensional network structure, polybutylene adipate terephthalate resin as a raw material may contain function-imparting materials such as antioxidants and lubricants. These function-imparting materials can be used individually or in combination of 2 or more types. It is preferable to adjust the content of the function-imparting material by kneading various function-imparting materials into the resin during melt extrusion according to the color tone and appearance quality of the resin after melting.

As the antioxidant, known phenolic antioxidants, phosphite antioxidants, thioether antioxidants, benzotriazole ultraviolet absorbers, triazine ultraviolet absorbers, benzophenone ultraviolet absorbers, etc. agent, NH type hindered amine light stabilizer, N- _CH3 type hindered amine light stabilizer, etc., preferably contain at least one of these antioxidants.

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-tertiary butylphenyl)butane, 4,4'-Butylenebis(6-tertiary butyl m-cresol), 3-(3,5-ditertiary butyl-4-hydroxyphenyl)stearyl propionate, pentaerythritol tetrakis[3- (3,5-ditertiary butyl-4-hydroxyphenyl)propionate], Sumilizer AG 80, 2,4,6-tris(3',5'-ditertiary butyl-4'-hydroxy Benzyl) mesitylene, etc.

Examples of phosphite antioxidants include: 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undeca Alkane, 3,9-bis(2,6-ditertiary 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] Dioxaphosphaoctacycline, tris(2,4-two tertiary butylphenyl) phosphite, tris(4-nonylphenyl) phosphite, 4,4'- Isopropyl diphenyl C12-15 alcohol phosphite, diphenyl (2-ethylhexyl) phosphite, diphenyl isodecyl phosphite, triisodecyl phosphite, triphenyl phosphite wait.

Examples of thioether-based antioxidants include bis[3-(dodecylthio)propionic acid]2,2-bis[[3-(dodecylthio)-1-oxopropoxy ]methyl]-1,3-propanediester, 3,3'-di(tridecyl)thiodipropionate, etc.

In order to prevent the thermal deterioration of resin, it is preferable to mix and use a phenolic antioxidant and a phosphite antioxidant. The content of these two antioxidants is preferably from 0.05 mass % to 1.0 mass % with respect to 100 mass % of the resin composition.

The lubricant may, for example, be a hydrocarbon wax, a higher alcohol wax, an amide wax, an ester wax, or a metal soap. If necessary, it is preferable to contain the lubricant in an amount of 0.5% by mass or less on a mass basis with respect to 100% by mass of the resin composition.

This application claims the benefit of priority based on Japanese Patent Application No. 2021-058475 filed on March 30, 2021. The entire contents of the specification of Japanese Patent Application No. 2021-058475 filed on March 30, 2021 are incorporated herein by reference. [Example]

Hereinafter, examples are given to illustrate the present invention more specifically, but the present invention is not limited by the following examples, and can also be modified and implemented within the scope of meeting the aforementioned/later-described gist, and these are included in this document. within the technical scope of the invention.

The measurement and evaluation of the characteristic values of the three-dimensional network structures of Examples 1 to 7 and Comparative Examples 1 to 3 described later were performed based on the following methods. In addition, the size of the sample is based on the size described below as a standard, but when the sample is insufficient, a sample of a feasible size is used for measurement.

(1) Fiber diameter The three-dimensional network structure was cut into a size of 10 cm×10 cm, and linear fibers were collected from 10 locations with a length of about 5 mm. Next, the diameter was measured by focusing on the fiber diameter measurement site of the collected linear fibers using an optical microscope, and the average value of the fiber diameters at 10 sites was obtained (n=10).

(2) Hollow ratio Ten linear fibers were randomly extracted from the three-dimensional network structure. Next, the linear fiber was cut transversely, mounted on a glass slide in a state of standing upright along the fiber axis direction, and the cross section of the fiber in the transverse direction was observed with an optical microscope. At this time, only the linear fibers whose cross-section is hollow are selected, and the area (a) and hollow area (b) inside the outer peripheral line of the fiber are respectively calculated, and the hollow ratio is calculated based on the following formula to obtain the selected hollow linear fiber. The average value of the hollow ratio of the fiber. Hollow ratio (%)=(b)/(a)×100

(3) Thickness and apparent density Cut the three-dimensional network structure into a size of 10cm x 10cm along the vertical and horizontal directions. After placing the obtained sample under no load for 24 hours, use the The FD-80N thickness gauge measures the height of one central part, and the height of the sample is taken as the thickness of the three-dimensional network structure. Furthermore, the sample was placed on the electronic balance, and the sample weight was measured. The volume of the sample was obtained by multiplying the height of the sample by the vertical and horizontal areas (100 cm ² ), and the apparent density was obtained by dividing the weight of the sample by the volume. This operation was performed three times, and the average value (n=3) of the thickness and apparent density of the three-dimensional network structure was obtained.

(4) Melting point (Tm) Calculate the endothermic peak (melting peak) temperature according to the endothermic and exothermic curve. The aforementioned endothermic and exothermic curve uses the differential scanning calorimeter Discovery DSC25 manufactured by TA Instruments to collect samples from the three-dimensional network structure. The sample mass weighs 2.0 mg ± 0.1 mg, measured under the conditions of a heating rate of 20°C/min and a nitrogen atmosphere. This operation was performed three times, and the average value of the melting point was obtained (n=3).

(5) Melting enthalpy Calculate the enthalpy of crystal fusion (J/g) from the integral value of the endothermic peak (melting peak) according to the endothermic and exothermic curve. The aforementioned endothermic and exothermic curve is a sample collected from the three-dimensional network structure, and the sample mass is weighed as 2.0 mg ± 0.1 mg. It was measured using a differential scanning calorimeter Discovery DSC25 manufactured by TA Instruments under conditions of a heating rate of 20° C./min and a nitrogen atmosphere. Specifically, the integrated value of the endothermic peak (melting peak) is obtained by setting the point at which the curve of the endothermic peak (melting peak) separates from the reference line on the low temperature side as the starting point, and starting to contact the high temperature Set the point of the reference line on the side as the end point, draw a straight line connecting the start point and the end point, and perform integration for the part surrounded by the straight line and the curve. This operation was performed three times, and the average value (n=3) of crystal fusion enthalpy was obtained. In addition, let the said onset point be the onset temperature (degreeC) which starts melting.

(6) Melt flow rate (MFR) The three-dimensional network structure was finely chopped as a raw material, and after vacuum drying at 80° C. for more than 2 hours, the melt flow rate (MFR) measurement was carried out quickly so as not to contain moisture in the air as much as possible. The melt flow rate was measured according to ISO1133 using a Melt Indexer F-F01 machine manufactured by Toyo Seiki Seisakusho. The measurement temperature was set to 190° C., and the load was set to 2.16 kg. This operation was performed three times, and the average value of the melt flow rate was obtained (n=3).

(7) Weight average molecular weight The sample was collected from the three-dimensional network structure, and in order to reduce the deviation of the sample, the sample was finely cut and dissolved in 40 mg, 10 times the usual amount. The sample solution was diluted with chloroform to adjust the sample concentration to 0.05%. The GPC analysis of the sample solution obtained by filtering with the membrane filter of 0.2 micrometers was implemented under the following conditions. The molecular weight was calculated in terms of standard polystyrene. Device: TOSOH HLC-8320GPC Column: TSKgel SuperHM-H×2＋TSKgel SuperH2000(TOSOH) Solvent: Chloroform Flow rate: 0.6ml/min Concentration: 0.05% Injection volume: 20μL Temperature: 40°C Detector: RI, UV254nm (8) Compressive residual strain at 70°C The three-dimensional network structure was cut into a size of 10 cm×10 cm, and the thickness (c) before treatment was measured for the obtained sample by the method described in (2) above. The sample whose thickness has been measured is clamped in a jig that can maintain a 50% compressed state, and placed in a dryer set at 70°C for 22 hours. Then, the sample was taken out and cooled, and the thickness (d) was determined after releasing the compressive strain and leaving for 30 minutes. These thicknesses were substituted into {(c)-(d)}/(c)×100 to obtain the 70° C. compression residual strain. This operation was performed three times, and the average value of the 70°C compression residual strain was obtained (n=3).

(9) Hardness at 25% compression The three-dimensional network structure was cut into a size of 10cm×10cm, and the obtained sample was placed in an environment of 23°C±2°C without load for 24 hours. Then, measurement was performed in accordance with ISO2439(2008) E method in an environment of 23°C±2°C using Autograph AG-X plus manufactured by Shimadzu Corporation. Specifically, a pressure plate with a diameter (φ) of 50 mm was placed at the center of the sample, and the thickness when the load became 0.5 N was measured, and this thickness was taken as the initial thickness. Set the position of the pressure plate at this time to zero, perform a pre-compression at a speed of 100mm/min until 75% of the initial thickness, return the pressure plate to zero at the same speed, and leave it in this state for 4 minutes. Immediately thereafter, compression was performed at a rate of 100 mm/min to 25% of the initial thickness, the load at this time was measured, and this load was defined as the hardness (N/φ50mm) at 25% compression. This operation was performed three times, and the average value of the hardness at 25% compression was obtained (n=3).

As the polybutylene adipate terephthalate resin, TH-801T manufactured by XINJIANG BLUE RIDGE TUNHE CHEMICAL INDUSTRY JOINT STOCK was used. The weight average molecular weight of the resin was 12.3×10 ⁴ g/mol, and the melt flow rate (MFR) was 4 g/10 minutes.

[Example 1] The water tank was arranged so that the cooling water surface was located 17 cm below the nozzle surface of the nozzle for spraying molten resin, the water temperature was set to 12°C, and a pair of traction conveyor belts were arranged in the water tank so that a part was exposed to the water surface. The traction conveyor belt has a stainless steel ring wire with a width of 20cm. The width direction of the nozzle surface is arranged parallel to the conveyor belt. The opening width of the ring wire is set to 30mm. It is configured so that water flows at a rate of 1.0L/min to form side faces.

As the above-mentioned nozzle for ejecting molten resin, the following nozzle was used: 0.5 mm outer diameter and circular hole shape orifices were formed in a staggered arrangement with a distance between holes of 6 mm on the nozzle effective surface of 96 mm in the width direction and 31 mm in width in the thickness direction. Dry the resin as a raw material to make it absolutely dry, add 0.01 mass% of water to 100 mass% of the solid content of the resin, and then spray it to the nozzle at a spinning temperature of 260°C and a single-hole discharge rate of 1.0g/min. Molten resin spouts from below.

The above-mentioned molten resin is sprayed into the opening of the mesh of the conveyor belt, the mesh of the conveyor belt, and the aluminum plate of the above-mentioned side part in a linear form, and the continuous linear body is dropped and bent to form a loop. The welding side forms a three-dimensional network structure. While the two sides of the three-dimensional network structure in the molten state are clamped by the traction conveyor belt, they are pulled into the cooling water at a speed of 0.86m/min to solidify, thereby flattening the respective two sides in the thickness direction and the side direction After that, cut into predetermined size. Then, it was left to stand in a space at 25° C. for 1 hour. The moisture content of the obtained three-dimensional network structure was 9%, and it was dried with hot air at 80° C. for 20 minutes, and then annealed to obtain a three-dimensional network structure with a width of 100 mm. The cross-sectional shape of the linear fibers of the three-dimensional network structure is circular.

[Example 2] Water was added in an amount of 0.30% by mass relative to 100% by mass of the solid content of the resin, and a cross-section with an outer diameter of 5.0 mm, an inner diameter of 4.4 mm and a triple bridge (triple bridge) was formed in a staggered arrangement with a pitch of 8 mm. For the nozzle of the orifice, the spinning temperature is set to 231°C, the single-hole ejection amount is set to 1.5g/min, the pulling speed is set to 0.92m/min, and the drying temperature is set to 105°C. In addition, the same as in Example 1 A three-dimensional network structure is obtained in the same manner. The cross-sectional shape of the linear fibers of the three-dimensional network structure is hollow.

[Example 3] A three-dimensional network was obtained in the same manner as in Example 2, except that water was added in an amount of 0.40% by mass relative to 100% by mass of the solid content of the resin, and the spinning temperature was set to 230°C and the drying temperature was set to 90°C. structure.

[Example 4] Water was added in an amount of 0.01% by mass relative to 100% by mass of the solid content of the resin, the spinning temperature was set at 240°C, and the nozzle surface-cooling water distance was set at 25 cm. Obtained in the same manner as in Example 3 Three-dimensional network structure.

[Example 5] A three-dimensional network structure was obtained in the same manner as in Example 1, except that water was not added after drying the resin as a raw material, the discharge rate per hole was set to 0.5 g/min, and the pulling speed was set to 0.64 m/min.

[Example 6] Water was added in an amount of 0.20% by mass relative to 100% by mass of the solid content of the resin, the spinning temperature was set at 190°C, and the distance between the nozzle face and the cooling water was set at 30 cm, and obtained in the same manner as in Example 3. Three-dimensional network structure.

[Example 7] A three-dimensional network structure was obtained in the same manner as in Example 5, except that the spinning temperature was 210° C., the discharge amount per hole was 1.0 g/min, and the drawing speed was 1.28 m/min.

[Comparative example 1] 2.5 mass% of water is added to the solid content of the resin at 100 mass%, the discharge rate per hole is set at 0.9g/min, the nozzle surface-cooling water distance is set at 18cm, and the pulling speed is set at 0.52m/min. A three-dimensional network structure was obtained in the same manner as in Example 1.

[Comparative example 2] A three-dimensional network was obtained in the same manner as in Example 4, except that water was added in an amount of 0.02% by mass relative to 100% by mass of the solid content of the resin, and dried at 20°C to 25°C for 2 days without annealing. structure.

[Comparative example 3] A three-dimensional network structure was obtained in the same manner as in Example 2 except that the spinning temperature was 230°C, the drawing speed was 1.54 m/min, and the drying temperature was 107°C.

Table 1 shows the production conditions in Examples 1 to 7, Comparative Examples 1 to 3, and the properties of the obtained three-dimensional network structures. In addition, in Table 1, the numerical value of the characteristic evaluated several times is an average value.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative example 1 Comparative example 2 Comparative example 3 manufacturing steps Amount of water added (mass%) 0.01 0.30 0.40 0.01 0.00 0.20 0.00 2.50 0.02 0.30 Spinning temperature (℃) 260 231 230 240 260 190 210 260 240 230 Single hole discharge (g/min) 1.0 1.5 1.5 1.5 0.5 1.5 1.0 0.9 1.5 1.5 Nozzle surface - cooling water distance (cm) 17 17 17 25 17 30 17 18 25 17 Traction speed (m/min) 0.86 0.92 0.92 0.92 0.64 0.92 1.28 0.52 0.92 1.54 Moisture content (mass %) of the three-dimensional network structure before annealing 9 10 9 11 12 8 12 16 12 10 Annealing temperature (℃) 80 105 90 90 80 90 80 80 - 107 Annealing time (minutes) 20 20 20 20 20 20 20 20 - 20 Three-dimensional network structure Fiber diameter (mm) 0.63 0.72 0.71 0.90 0.56 0.72 0.75 0.28 0.90 0.75 Hollow rate (%) 0 2.8 2.7 14.0 0 17.4 0 0 13.8 3.4 Apparent density (g/cm ³ ) 0.069 0.060 0.055 0.055 0.053 0.051 0.056 0.044 0.056 0.039 Thickness (mm) 25.3 23.4 23.9 27.0 25.9 26.3 24.6 28.9 26.8 21.4 Melt Flow Rate (MFR) (g/10min) 7 twenty two twenty three 8 6 twenty two 5 71 7 twenty two Weight average molecular weight (g/mol) 105000 75000 71000 103000 113000 76000 123000 30000 111000 51000 Melting point (°C) 119.5 114.0 101.4 110.0 124.5 101.9 124.2 124.5 124.0 112.7 The starting temperature of melting (°C) 84.8 106.6 93.1 93.4 84.6 94.6 85.3 85.0 87.1 107.0 Fusion enthalpy (J/g) 20.4 16.0 18.4 21.7 23.5 21.3 22.0 19.6 15.1 14.4 70℃ Compression Residual Strain (%) 20.1 28.2 19.1 21.1 20.2 16.7 23.5 31.2 38.5 32.1 Hardness at 25% compression (N/φ50mm) 12.7 5.4 8.7 5.5 7.5 8.1 7.6 5.3 4.8 1.8

The three-dimensional network structures obtained in Examples 1 to 7 are excellent in compression durability and compression recovery after heating and compression. Furthermore, in Examples 1 to 6, since the melt viscosity of the polymer at the time of ejection can be reduced, delicate rings can be produced, and the surface and appearance quality are excellent.

The weight-average molecular weight of the network structure obtained in Comparative Example 1 was low, and the compression recovery after heating and compression was poor. In addition, the network structure obtained in Comparative Example 1 was slightly yellowed. This is considered to be influenced by the high water content of the three-dimensional network structure before annealing.

The network structures obtained in Comparative Example 2 and Comparative Example 3 had low crystal fusion enthalpy, poor compression durability and compression recovery after heating and compression.

[ Fig. 1 ] is an example of an endothermic and exothermic curve for measuring the crystal melting enthalpy of linear fibers contained in a three-dimensional network structure.

Claims (8)

A biodegradable three-dimensional network structure with an apparent density of 0.005g/cm ³ to 0.30g/cm ³ ; a thickness of 10mm to 100mm; comprising linear fibers, the fiber diameter of which is 0.2mm to 2.0 mm, the crystal fusion enthalpy is 16 J/g or more, and contains polybutylene adipate terephthalate-based resins with a weight average molecular weight of 35,000 or more. The biodegradable three-dimensional network structure as described in claim 1, wherein the linear fibers form a three-dimensional random ring structure. The biodegradable three-dimensional network structure as claimed in claim 1 or 2, wherein the melting enthalpy of the aforementioned crystals is 30 J/g or less. The biodegradable three-dimensional network structure as described in claim 1 or 2 is used for a cushion. The biodegradable three-dimensional network structure according to claim 1 or 2, wherein the weight average molecular weight of the polybutylene adipate terephthalate resin is 150,000 or less. The biodegradable three-dimensional network structure as claimed in claim 1 or 2, wherein the melting point of the linear fibers is not less than 100°C and not more than 120°C. The biodegradable three-dimensional network structure according to claim 1 or 2, wherein the linear fibers have a hollow cross-sectional shape. The biodegradable three-dimensional network structure as described in claim 7, wherein the hollow rate of the linear fibers is not less than 1% and not more than 30%.

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