JP7207614B1 - Biodegradable three-dimensional network structure - Google Patents

Abstract

A biodegradable three-dimensional network structure excellent in compression durability and compression recovery after heat compression. An apparent density of 0.005 g/cm3 to 0.30 g/cm3, a thickness of 10 mm to 100 mm, and containing linear fibers, the linear fibers having a fiber diameter of 0.2 mm to 2.0 mm, A biodegradable three-dimensional network structure comprising a polybutylene adipate terephthalate resin having a crystal melting enthalpy of 16 J/g or more and a weight average molecular weight of 35000 or more.

Description

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

Various biodegradable three-dimensional network structures have been known so far. For example, in Patent Document 1, a biodegradable aquatic plant support for greening comprising a three-dimensional network having three-dimensional random loops in which a large number of continuous winding linear bodies having a biodegradable thermoplastic resin are joined at least partially. is disclosed. In Patent Document 2, a biodegradable three-dimensional net-like fibrous material aggregate is composed of a plurality of fibrous materials that are locally bonded to each other, and the fibrous material is composed of a biodegradable resin and a local Disclosed is a three-dimensional reticulated fibrous material aggregate having at least a composition that includes a bonding-enhancing resin for targeted bonding. In addition, in Patent Document 3, filaments having a fineness of 300 to 100,000 denier and mainly composed of thermoplastic polylactic acid resin are repeatedly bent and joined at most of the contact parts to have a biodegradable three-dimensional structure. body is disclosed.

JP-A-2001-32236 Japanese Patent Application Laid-Open No. 2020-128608 Japanese Patent Application Laid-Open No. 2000-328422

Patent Literature 1 discloses a technique for improving the plant retention of a biodegradable network structure. Further, Patent Document 2 discloses a technique for improving local bonding of fiber materials of a biodegradable network structure. In addition, Patent Document 3 discloses a technique in which a coil spring-like or loop-like portion is formed in a biodegradable three-dimensional structure so that the portion is suitably deformed against compressive stress to disperse the stress. disclosed. Thus, various attempts have been made so far to improve the function of biodegradable network structures. The active network structure is not yet known. The present invention has been made in view of the above circumstances, and an object thereof is to provide a biodegradable three-dimensional network structure excellent in compression durability and compression recovery after heat compression.

A biodegradable three-dimensional network structure according to an embodiment of the present invention is as follows.
[1] an apparent density of 0.005 g/cm ³ to 0.30 g/cm ³ ;
The thickness is 10 mm to 100 mm,
A polybutylene adipate terephthalate resin having a fiber diameter of 0.2 mm to 2.0 mm, a crystal melting enthalpy of 16 J/g or more, and a weight average molecular weight of 35000 or more. A biodegradable three-dimensional network structure comprising:

With the above configuration, compression durability and compression recovery after heat compression can be improved. Preferred embodiments of the biodegradable three-dimensional network structure are as follows.
[2] The biodegradable three-dimensional network structure according to [1], wherein the linear fibers form a three-dimensional random loop structure.
[3] The biodegradable three-dimensional network structure according to [1] or [2], wherein the crystal melting enthalpy is 30 J/g or less.
[4] The biodegradable three-dimensional network structure according to any one of [1] to [3], which is used for cushions.
[5] The biodegradable three-dimensional network structure according to any one of [1] to [4], wherein the polybutylene adipate terephthalate 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 according to [7], wherein the linear fibers have a hollowness of 1% or more and 30% or less.
[9] The biodegradable three-dimensional network structure according to [7], wherein the linear fibers have a hollowness of 2% or more and 25% or less.
[10] The biodegradable three-dimensional network structure according to any one of [1] to [9], wherein the crystal melting enthalpy is 17 J/g or more.
[11] The biodegradable three-dimensional network structure according to any one of [1] to [10], wherein the crystal melting enthalpy 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.

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

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

A biodegradable three-dimensional network structure according to an 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 contains linear fibers. The linear fibers contain a polybutylene adipate terephthalate resin having a fiber diameter of 0.2 mm to 2.0 mm, a crystal melting enthalpy of 16 J/g or more, and a weight average molecular weight of 35000 or more. Compression durability and compression recovery after heat compression can be improved by the above configuration. Each configuration will be described in detail below.

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

The three-dimensional network structure has a thickness of 10 mm to 100 mm. When the thickness is 10 mm or more, the three-dimensional network structure can be easily used as a cushioning material or the like. The thickness is preferably 15 mm or more, more preferably 20 mm or more, still more preferably 22 mm or more. On the other hand, considering the size of the manufacturing apparatus, the thickness is 100 mm or less, preferably 90 mm or less, more preferably 80 mm or less, and even more preferably 50 mm or less. The thickness of the three-dimensional network structure can be measured by the method described in Examples below.

The three-dimensional network structure contains linear fibers. The linear fibers preferably form a three-dimensional random loop structure. Further, the filamentous fibers are preferably continuous filaments. A continuous filament is a linear filament having a continuous portion of at least 5 mm or more. A three-dimensional network structure can be easily formed by having a portion where the crossing portions of the continuous filaments are adhered. Therefore, it is preferable that the three-dimensional network structure has a bonding portion where the crossing portions of the linear fibers are bonded together.

The linear fiber may be a sheath-core type, side-by-side type, eccentric sheath-core type composite linear body, or the like. The composite linear body may be a composite linear body obtained by combining a polybutylene adipate terephthalate-based resin and another thermoplastic resin. The cross-sectional shape of the linear fibers may be either a hollow cross section or a solid cross section. In addition, since the cross-sectional shape of the filamentous fibers is a hollow cross-section, recovery from compression after heat-compression is improved. Moreover, the cross-sectional shape of the linear fibers is preferably an irregular cross-section. This makes it possible to easily impart suitable hardness and cushioning properties to the three-dimensional network structure. The hollowness of the linear fibers is preferably 1% or more, more preferably 2% or more, still more preferably 5% or more, and preferably 30% or less, more preferably 25% or less, further preferably 20% or less. is. The hollowness of the linear fibers can be measured by the method described in Examples below.

Linear fibers have a fiber diameter of 0.2 mm to 2.0 mm. The hardness is improved when the fiber diameter is 0.2 mm or more. Therefore, the fiber diameter is preferably 0.3 mm or more, more preferably 0.4 mm or more. On the other hand, when the fiber diameter is 2.0 mm or less, the denseness of the network structure can be improved, the cushioning property and the like can be improved, and the feel of the network structure can be easily made soft. Therefore, the fiber diameter is preferably 1.7 mm or less, more preferably 1.5 mm or less, still more preferably 1.2 mm or less. The fiber diameter of the linear fibers can be measured by the method described in Examples below. The profile shape of the cross-section of the linear fibers may be circular, elliptical, polygonal, or polygonal with rounded corners. The fiber diameter of a fiber whose contour has a shape other than a circle corresponds to the longest distance between any two points on the contour of the fiber.

Preferably, the linear fibers have a melt flow rate (MFR) of 3 g/10 minutes to 60 g/10 minutes. When the MFR is 3 g/10 minutes or more, the melt viscosity can be easily improved, and the fiber diameter of the linear fibers can be increased. MFR is more preferably 4 g/10 min or more, still more preferably 6 g/10 min or more, even more preferably 8 g/10 min or more, and particularly preferably 10 g/10 min or more. On the other hand, when the MFR is 60 g/10 minutes or less, the recovery from compression after heat compression can be easily improved. MFR is more preferably 50 g/10 min or less, still more preferably 40 g/10 min or less, even more preferably 30 g/10 min or less, and particularly preferably 25 g/10 min or less. The MFR of linear fibers can be measured by the method described in Examples below.

When using a commercially available resin as the polybutylene adipate terephthalate-based resin constituting the linear fiber, if the melt flow rate (MFR) of the resin is low, water is added to the resin to hydrolyze the resin during melt extrusion. By increasing the MFR of the resin, the MFR can be improved. Thereby, the MFR of the linear fibers can be improved. 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 melt extruding it. Thereby, the MFR of the linear fibers can be reduced.

The linear fibers have a crystalline melting enthalpy of 16 J/g or more. When the crystal melting enthalpy is 16 J/g or more, the compression durability of the three-dimensional network structure and the compression recovery after heat compression can be improved. Crystal melting enthalpy is preferably 17 J/g or more, more preferably 18 J/g or more, still more preferably 19 J/g or more, even more preferably 20 J/g or more, and particularly preferably 21 J/g or more. is. On the other hand, the crystal melting enthalpy is preferably 30 J/g or less. As a result, the flexibility of the three-dimensional network structure is improved, and noise generated during compression and recovery can be reduced. The crystal melting enthalpy is more preferably 28 J/g or less, still more preferably 26 J/g or less.

The crystal melting enthalpy (J/g) of the linear fiber was measured using a differential scanning calorimeter with a sample mass of 2.0 mg ± 0.1 mg at a heating rate of 20 ° C./min under a nitrogen atmosphere. It can be determined from the integrated value of the endothermic peak (melting peak) of the curve. The integral value is defined by starting at the point where the curve related to the endothermic peak (melting peak) begins to separate from the baseline on the low temperature side and ending at the point at which it begins to contact the baseline on the high temperature side. It can be obtained by drawing a connecting straight line and integrating the portion surrounded by the straight line and the curved line. An example of the endothermic curve is shown in FIG. The dashed line in FIG. 1 is a straight line connecting the start point and the end point of the endothermic peak (melting peak), and the portion surrounded by the dashed line and the curved line is the integration region where integration is performed.

In the case where a commercially available resin is used as the polybutylene adipate terephthalate-based resin constituting the linear fiber and the crystalline melting enthalpy is lower than the desired range, the crystalline melting enthalpy is lowered by annealing as described later. It can be controlled within a desired range.

A polybutylene adipate terephthalate resin is a biodegradable resin and is a copolymer of adipic acid, terephthalic acid and butanediol. Since the polybutylene adipate terephthalate-based resin is a biodegradable resin, it is expected to be one of the solutions to the waste disposal problem and the microplastic problem. Adipic acid, terephthalic acid, and butanediol do not need to be copolymerized at the same time, and may be copolymerized in multiple stages. Also, the polybutylene adipate terephthalate resin is preferably a thermoplastic resin.

In synthesizing the polybutylene adipate terephthalate resin, a trace amount of other copolymer components may be added in addition to adipic acid, terephthalic acid and butanediol. Other copolymerization components include dicarboxylic acids other than terephthalic acid and adipic acid, and modifiers for the purpose of chain extension, terminal blocking, and the like. These may be used alone or in combination of two or more.

Other dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, and the like. These may be used alone or in combination of two or more.

Modifiers include polyisocyanate compounds, glycol compounds, and the like. A diisocyanate compound is mentioned as a polyisocyanate compound. Diisocyanate compounds include hexamethylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, 1,5-naphthylene diisocyanate, p-phenylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylene diisocyanate, carbodiimide-modified MDI, polymethylenephenyl polyisocyanate and the like. These may be used alone or in combination of two or more. Glycol compounds include diols other than butanediol and polyalkylene glycols. Other diols include methanediol, ethanediol, propanediol, pentanediol, hexanediol, and the like. Polyalkylene glycols include polymethylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol (polytetramethylene glycol) and the like. These may be used alone or in combination of two or more.

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

The weight average molecular weight (g/mol) of the polybutylene adipate terephthalate resin is 35000 or more. Thereby, compression recoverability after heat compression can be improved. The weight average molecular weight is preferably 37,000 or more, more preferably 40,000 or more. On the other hand, when the weight average molecular weight is 150,000 or less, flexibility can be improved. The weight average molecular weight is preferably 150,000 or less. In addition, when the weight average molecular weight is 120,000 or less, the melt viscosity of the polymer can be reduced. The weight average molecular weight is more preferably 120,000 or less. Also, the weight average molecular weight (g/mol) of the resin constituting the linear fibers is preferably within the range. The weight average molecular weight can be determined by gel permeation chromatography (GPC) or the like.

The linear fibers may contain biodegradable resins other than the polybutylene adipate terephthalate resin. Other biodegradable resins include polylactic acid, polylactic acid/polycaprolactone copolymer, polylactic acid/polyether copolymer, polyethylene terephthalate succinate, polybutylene succinate, polybutylene succinate adipate, polyglycolic acid, Polycaprolactone, polyvinyl alcohol, cellulose acetate and the like are preferred. These may be used alone or in combination of two or more. For details, refer to the positive list of Classification No. A-1 of GreenPla (biodegradable plastic) of Japan Bioplastics Association. The linear fibers may contain resins other than biodegradable resins. Examples of the resin include thermoplastic resins such as polyurethane and polyester.

A petroleum-derived monomer may be used as a monomer for synthesizing the resin constituting the linear fiber, but it is preferable to use a biomass-derived monomer because it can reduce the environmental load. For biomass-derived monomers, for example, the monomers listed in the positive list of classification number A (biomass plastics) of the Japan Bioplastics Association can be referred to.

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

Linear fibers may contain deodorants, antibacterial agents, antifungal agents, antimite agents, deodorants, antifungal agents, fragrances, flame retardants, moisture absorption and desorption agents, antioxidants, lubricants, and the like. . These may be used alone or in combination of two or more.

The content of the polybutylene adipate terephthalate-based resin in 100% by mass of the linear fiber is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 80% by mass or more, It is even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 98% by mass or more. The linear fibers may also be made of polybutylene adipate terephthalate resin.

The linear fibers preferably have a melting point of 100° C. or higher and 120° C. or lower. As a result, it is possible to easily improve the compression recoverability of the three-dimensional network structure after heat compression. The melting point is more preferably 115° C. or lower. 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 fibers can be easily lowered to 120° C. or lower.

The three-dimensional network structure may have a multilayer structure. As a multilayer structure, the surface layer and the back layer are composed of linear fibers with different fineness, the surface layer and the back layer are composed of structures with different apparent densities, long fiber nonwoven fabrics and short fiber nonwoven fabrics, etc. Examples thereof include those obtained by laminating and forming multiple layers. Examples of the multilayering method include a method of melting and fixing by heating, a method of bonding with an adhesive, and a method of restraining with sewing or a band.

The shape of the three-dimensional network structure is not particularly limited, and examples thereof include a plate shape, a polygonal shape such as a triangular prism and a quadrangular prism, a cylindrical shape, a spherical shape, and combinations thereof. When molding the three-dimensional network structure, it may be molded using a regulation plate during melt extrusion of the resin, or may be molded by cutting, hot pressing, or the like.

The three-dimensional network structure preferably has a 70° C. compression residual strain of 30% or less. Thereby, compression recoverability after heat compression can be improved. More preferably 25% or less, still more preferably 23% or less. The 70° C. compression residual strain may be 1% or more, or 5% or more. The 70° C. compression residual strain can be measured by the method described in Examples below.

The 25% compression hardness of the three-dimensional network structure is preferably 5.0 N/φ50 mm or more and 100 N/φ50 mm or less. When the strength is 5.0 N/φ50 mm or more, it is possible to reduce the feeling of bottoming out when the three-dimensional network structure is used as a cushioning material or the like. Therefore, it is more preferably 5.4 N/φ50 mm or more, still more preferably 6.0 N/φ50 mm or more, and even more preferably 7.0 N/φ50 mm or more. On the other hand, when it is 100 N/φ50 mm or less, the cushioning property can be improved. Therefore, it is more preferably 80 N/φ50 mm or less, still more preferably 60 N/φ50 mm or less, and even more preferably 30 N/φ50 mm or less. The 25% compression hardness can be measured by the method described in Examples below.

The three-dimensional network structure preferably does not contain a conjugation promoter. This makes it easier to prevent excessive hardening due to excessive bonding in the three-dimensional network structure by the bonding accelerator. In addition, it is possible to easily prevent a reduction in the denseness of the three-dimensional network structure due to an excessive increase in the bonding range per contact. Bonding promoting resins include polycaprolactone, polybutylene succinate, polybutylene sebacate terephthalate, polybutylene azelate terephthalate, and the like.

The three-dimensional network structure may be colored. Coloring agents such as pigments and dyes can be used for coloring. The colorant may be incorporated into the resin before melt spinning, or the linear fibers may be coated with the colorant by dipping or coating after forming the three-dimensional network structure.

The three-dimensional network structure is preferably used for cushions. The cushion may be any elastic material that supports objects or any material that reduces impact. Cushions for office chairs, furniture, sofas, bedding such as beds, cushions for vehicle seats such as trains, automobiles, motorcycles, child seats, strollers, etc., floor mats, impact absorption mats such as collision and pinch prevention members and cushions used for such purposes.

A three-dimensional network structure can be formed, for example, by the following method. First, from a multi-row nozzle having a plurality of orifices, a polybutylene adipate terephthalate-based resin is distributed to the nozzle orifices, and the spinning temperature of the resin is ((melting point + 20 ° C.) or higher to (melting point + 180 ° C.)) below the nozzle. Directly dispense. Next, the continuous filaments are brought into contact with each other in a molten state and fused to form a three-dimensional network structure, sandwiched between take-up conveyor nets, and cooled with cooling water in a cooling tank. The distance between the nozzle surface and the surface of the cooling water is preferably 15 cm or more, more preferably 20 cm or more. Thereby, the hollowness of the fiber and the denseness 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. This makes it easier to obtain a three-dimensional network structure having an appropriate apparent density and fiber diameter. After cooling, the solidified three-dimensional network structure is pulled out and drained or dried to obtain a three-dimensional network structure smoothed on one or both sides. The description in JP-A-7-68061 can be referred to for these spinning and cooling steps. In the case of smoothing only one surface, the continuous filaments are discharged onto an inclined take-up net, brought into contact with each other in a molten state, and fused together. At that time, the three-dimensional network structure is formed, and only the surface of the take-off net is cooled while the shape is relaxed. Annealing treatment is performed on the obtained three-dimensional network structure. Incidentally, the drying treatment of the three-dimensional network structure may be performed as an annealing treatment.

Water is preferably added to the resin before it is discharged from the nozzle. The amount of water charged is preferably 0.005% by mass or more relative to 100% by mass of the solid content of the resin. This can promote the decomposition of the resin in the manufacturing process of the three-dimensional network structure, and improve the flexibility of the resin. On the other hand, the amount of water charged is preferably 2.0% by mass or less. This makes it possible to prevent excessive decomposition of the resin in the manufacturing process of the three-dimensional network structure, and to facilitate improvement in recovery from compression after heat compression. The amount of water charged is more preferably 1.0% by mass or less, still more preferably 0.5% by mass or less, and even more preferably 0.2% by mass or less. The method of adding water to the resin is not particularly limited. %, a predetermined amount of pure water may be added.

The melt flow rate (MFR) of the polybutylene adipate terephthalate-based resin is preferably 0.5 or more and less than 20.0 less than the MFR of the desired three-dimensional network structure before melt extrusion. Since heat deterioration and shear deterioration of the resin are induced during melt extrusion, a three-dimensional network structure having a desired MFR can be easily obtained by controlling the MFR before melt extrusion as described above.

It is preferable to use cooling water for cooling the polybutylene adipate terephthalate-based resin after melt molding. Polybutylene adipate terephthalate-based resin may undergo mold shrinkage before being solidified by cooling. Therefore, it is sufficient to form a three-dimensional network structure having a width and a thickness that takes molding shrinkage into consideration, but molding shrinkage can be reduced by lowering the melting and solidifying temperature. Therefore, the temperature of the cooling water is preferably 20°C or lower, more preferably 15°C or lower. The cooling time with cooling water is preferably 30 seconds or longer. The cooling and solidification is preferably performed in a water tank.

Annealing may be performed using a commercially available hot air drying oven or in a warm water bath. Annealing temperature is 70° C. or higher. Thereby, the crystal melting enthalpy can be improved. It is preferably 75° C. or higher, more preferably 80° C. or higher. On the other hand, the annealing temperature is 105° C. or less. This also can improve the crystal melting enthalpy.

The annealing time is preferably 1 minute or longer. Thereby, the crystal melting enthalpy can be improved. The annealing time is more preferably 5 minutes or longer, still more preferably 10 minutes or longer, and even more preferably 15 minutes or longer. On the other hand, the annealing time is preferably 60 minutes or less. This makes it possible to reduce yellowing, odor, molecular weight reduction, and the like of the polybutylene adipate terephthalate-based resin due to decomposition and deterioration of the polymer during annealing. Productivity can also be improved. More preferably, the annealing time is 50 minutes or less.

After solidification by cooling, it is preferable to keep the temperature of 20° C. to 50° C. for 1 minute or longer before annealing. In the annealing treatment, the thickness may change due to its own weight, but by holding at a temperature of 20° C. to 50° C. after cooling and solidifying, the change in thickness due to annealing can be reduced. For example, after cooling and solidifying in a water bath, annealing may be performed by using a continuous dryer, keeping the temperature low in the first half of the oven, and increasing the temperature in the second half of the oven.

The water content of the three-dimensional network structure before annealing is preferably 15% or less. As a result, decomposition of the resin can be reduced. The water content is more preferably 12% or less, still more preferably 10% or less. The moisture content is calculated by the following formula. The mass after vacuum drying in the formula is the mass after performing vacuum drying at 90° C. for 2 hours.
Moisture content (%) of three-dimensional network structure = {(mass of three-dimensional network structure before vacuum drying) - (mass of three-dimensional network structure after vacuum drying)}/(mass of three-dimensional network structure before vacuum drying) ) x 100

At any stage from the manufacturing process of the resin of the three-dimensional network structure to the molding process, the resin has deodorant, antibacterial, antifungal, mite, deodorant, antifungal, aromatic, flame retardant, and absorption/release properties. A function such as wettability may be imparted. In addition, in producing the three-dimensional network structure, the polybutylene adipate terephthalate-based resin as a raw material may contain function-imparting agents such as antioxidants and lubricants. These may be used alone or in combination of two or more. It is preferable to adjust the content of the function-imparting material by kneading various function-imparting materials with the resin during the melt-extrusion, depending on the color tone and quality of the resin after melting.

Antioxidants include known phenol antioxidants, phosphite antioxidants, thioether antioxidants, benzotriazole ultraviolet absorbers, triazine ultraviolet absorbers, benzophenone ultraviolet absorbers, NH type Hindered amine light stabilizers, N--CH ₃ type hindered amine light stabilizers, etc., may be mentioned, and at least one of these is preferably contained.

Phenolic antioxidants include 1,3,5-tris[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-1,3,5-triazine-2,4 ,6(1H,3H,5H)-trione, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4′-butylidenebis(6-tert-butyl- m-cresol), 3-(3,5-di-tert-butyl-4-hydroxyphenyl)stearylpropionate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate ], Sumilizer AG 80, 2,4,6-tris(3′,5′-di-tert-butyl-4′-hydroxybenzyl)mesitylene and the like.

Phosphite 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-dimethyl Ethyl)-6-[(2-ethylhexyl)oxy]-12H-dibenzo[d,g]“1,3,2” dioxaphosphosine, tris(2,4-di-tert-butylphenyl)phosphite , tris(4-nonylphenyl) phosphite, 4,4'-Isopropylidenediphenol C12-15 alcohol phosphite, diphenyl phosphite (2-ethylhexyl), diphenyl isodecyl phosphite, triisodecyl phosphite, triphenyl phosphite, etc. is mentioned.

Thioether antioxidants include bis[3-(dodecylthio)propionic acid]2,2-bis[“3-(dodecylthio)-1-oxopropyloxy”methyl]-1,3-propanediyl, 3,3 and ditridecyl'-thiobispropionate.

In order to prevent thermal deterioration of the resin, it is preferable to use a mixture of a phenol antioxidant and a phosphite antioxidant. The content of these two antioxidants is preferably 0.05% by mass or more and 1.0% by mass or less with respect to 100% by mass of the resin composition.

Lubricants include hydrocarbon waxes, higher alcohol waxes, amide waxes, ester waxes, metallic soaps, and the like. If necessary, it is preferable to contain 0.5% by mass or less of a lubricant based on 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.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples, and it is possible to implement it by adding changes within the scope that can conform to the gist of the above and later descriptions. All of them are included in the technical scope of the present invention.

Measurement and evaluation of characteristic values of three-dimensional network structures of Examples 1 to 7 and Comparative Examples 1 to 3, which will be described later, were carried out according to the following methods. The size of the sample was standardized to the size described below, but when the sample was insufficient, a sample of a possible size was used for the measurement.

(1) Fiber diameter A three-dimensional network structure was cut into a size of 10 cm x 10 cm, and linear fibers having a length of about 5 mm were collected from 10 locations. Then, using an optical microscope, the fiber diameter measurement points of the collected linear fibers were focused and the diameter was measured, and the average value (n=10) of the fiber diameters at 10 points was determined.

(2) Hollowness Ten linear fibers were randomly taken out from the three-dimensional network structure. Next, the filamentous fibers were cut into round slices, placed on a slide glass while standing in the direction of the fiber axis, and the fiber cross section in the slice direction was observed with an optical microscope. At this time, only linear fibers whose fiber cross section is a hollow cross section are selected, the area (a) and the hollow area (b) within the outer peripheral line of the fiber are calculated, and the hollow ratio is calculated based on the following formula, The average value of the hollow ratio of the selected hollow linear fibers was obtained.
Hollow ratio (%) = (b) / (a) x 100

(3) Thickness, apparent density The three-dimensional network structure was cut into a size of 10 cm × 10 cm in the vertical and horizontal directions, and the obtained sample was left for 24 hours without load. The height of one center point was measured with an FD-80N thickness gauge, and the height of the sample was defined as the thickness of the three-dimensional network structure. Furthermore, the sample was placed on an electronic balance to measure the weight of the sample. The height of the sample was multiplied by the vertical and horizontal area (100 cm ² ) to obtain the volume of the sample, 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 of the three-dimensional network structure and the apparent density was determined.

(4) Melting point (Tm)
A sample was collected from the three-dimensional network structure using a differential scanning calorimeter Discovery DSC25 manufactured by TA Instruments, the sample mass was weighed to 2.0 mg ± 0.1 mg, and the temperature was increased at a rate of 20 ° C./min in a nitrogen atmosphere. The endothermic peak (melting peak) temperature was obtained from the endothermic and exothermic curves measured under the following conditions. This operation was performed three times, and the average melting point (n=3) was obtained.

(5) Melting enthalpy A sample was collected from the three-dimensional network structure, the sample mass was weighed to 2.0 mg ± 0.1 mg, and a differential scanning calorimeter Discovery DSC25 manufactured by TA Instruments was used, and the temperature was increased at a rate of 20 ° C. /min, and the crystal melting enthalpy (J/g) was obtained from the integrated value of the endothermic peak (melting peak) from the endothermic curve measured under nitrogen atmosphere. Specifically, the integrated value of the endothermic peak (melting peak) is defined by starting from the point where the curve related to the endothermic peak (melting peak) starts to separate from the baseline on the low temperature side and starting to contact the baseline on the high temperature side. A straight line connecting the start point and the end point was drawn, and a portion surrounded by the straight line and the curved line was integrated. This operation was performed three times, and the average value (n=3) of crystal melting enthalpy was obtained. The starting point was defined as the melting start onset temperature (°C).

(6) Melt flow rate (MFR)
The three-dimensional network structure was finely chopped as a raw material, vacuum-dried at 80° C. for 2 hours or more, and then melt flow rate (MFR) was quickly measured 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 manufactured by Toyo Seiki Seisakusho. The measurement temperature was 190° C. and the load was 2.16 kg. This operation was performed three times, and an average value (n=3) of the melt flow rate was obtained.

(7) Weight Average Molecular Weight A sample was taken from the three-dimensional network structure, and in order to reduce sample variation, the sample was finely cut into pieces of 40 mg, which is 10 times the usual amount, and dissolved. The sample solution was diluted with chloroform to prepare a sample concentration of 0.05%. After filtration through a 0.2 μm membrane filter, GPC analysis of the resulting sample solution was performed under the following conditions. The molecular weight was calculated in terms of standard polystyrene.
Apparatus: TOSOH HLC-8320GPC
Column: TSKgel SuperHM-H×2+TSKgel SuperH2000 (TOSOH)
Solvent: chloroform Flow rate: 0.6 ml/min
Concentration: 0.05%
Injection volume: 20 μL
Temperature: 40°C
Detector: RI, UV254nm
(8) 70° C. Compression Residual Strain The three-dimensional network structure was cut into a size of 10 cm×10 cm, and the thickness (c) of the obtained sample before treatment was measured by the method described in (2) above. A sample whose thickness was measured was sandwiched between jigs capable of maintaining a 50% compressed state, placed in a dryer set at 70° C., and allowed to stand for 22 hours. After that, the sample was taken out, cooled, the compressive strain was removed, and the thickness (d) was determined after standing for 30 minutes. These thicknesses were applied to the formula {(c)−(d)}/(c)×100 to obtain the 70° C. compressive residual strain. This operation was performed three times, and an average value (n=3) of 70° C. compression residual strain was obtained.

(9) Hardness at 25% Compression The three-dimensional network structure was cut into a size of 10 cm×10 cm, and the obtained sample was left in an environment of 23° C.±2° C. for 24 hours without load. Then, it was measured in accordance with ISO2439 (2008) E method using Shimadzu Autograph AG-X plus in an environment of 23°C ± 2°C. Specifically, a pressure plate with a diameter (φ) of 50 mm was placed at the center of the sample, and the thickness was measured when the load reached 0.5 N, and this was taken as the initial thickness. With the position of the pressure plate at this time as the zero point, pre-compression is performed once to 75% of the initial thickness at a speed of 100 mm / min. bottom. After that, it was immediately compressed to 25% of the initial thickness at a speed of 100 mm/min, and the load at that time was measured, and the load was defined as hardness at 25% compression (N/φ50 mm). This operation was performed three times, and an average value (n=3) of hardness at 25% compression was determined.

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

[Example 1]
A water tank was placed so that the cooling water surface was positioned 17 cm below the nozzle surface of the nozzle for discharging the molten resin, the water temperature was set to 12°C, and a pair of take-up conveyors was placed in the water tank so that a part of it appeared above the water surface. bottom. The take-up conveyor has a stainless steel endless net with a width of 20 cm. The conveyor is arranged parallel to the width direction of the nozzle surface. The opening width of the endless net is 30 mm. It was arranged at an angle of 90 degrees with respect to the direction, and water was flowed at a rate of 1.0 L/min to form a side portion.

As a nozzle for discharging the molten resin, a nozzle having an outer diameter of 0.5 mm and round hole-shaped orifices formed in a staggered arrangement with an inter-hole pitch of 6 mm is used on a nozzle effective surface of 96 mm in the width direction and 31 mm in the width direction in the thickness direction. board. After drying the raw material resin to absolute dryness, adding 0.01% by mass of water to 100% by mass of the solid content of the resin, the spinning temperature was 260 ° C. and the single hole discharge rate was 1.0 g / min. Molten resin was discharged downward from the nozzle.

The molten resin is linearly discharged onto the opening of the conveyor net, on the conveyor net, and onto the aluminum plate on the side surface, and the continuous linear body is dropped to form a winding loop. Then, a three-dimensional network structure was formed while fusing the contact portions. Both sides of the three-dimensional network structure in the molten state are sandwiched by a take-up conveyor, drawn into cooling water at a speed of 0.86 m/min, and solidified to flatten both sides in the thickness direction and the side direction. cut to size. Then, it was allowed to stand in a space of 25°C for 1 hour. The resulting three-dimensional network structure had a water content of 9% and was annealed by drying with hot air at 80° C. for 20 minutes 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 was round.

[Example 2]
Water was added at a charge amount of 0.30% by mass based on the solid content of the resin of 100% by mass. The same as Example 1 except that the nozzles formed in an array were used, the spinning temperature was 231 ° C., the single hole discharge rate was 1.5 g / min, the take-up speed was 0.92 m / min, and the drying temperature was 105 ° C. A three-dimensional network structure was obtained in the same manner. The cross-sectional shape of the linear fibers of the three-dimensional network structure was hollow.

[Example 3]
A three-dimensional network was formed in the same manner as in Example 2 except that water was added at a charge amount of 0.40% by mass based on the solid content of the resin of 100% by mass, the spinning temperature was 230 ° C., and the drying temperature was 90 ° C. Got a struct.

[Example 4]
The procedure was the same as in Example 3 except that water was added at a charge amount of 0.01% by mass based on the solid content of the resin of 100% by mass, the spinning temperature was 240 ° C., and the nozzle surface-cooling water distance was 25 cm. We obtained a three-dimensional network structure.

[Example 5]
A three-dimensional network was formed in the same manner as in Example 1, except that water was not added after drying the raw material resin, the single hole discharge rate was 0.5 g / min, and the take-up speed was 0.64 m / min. Got a struct.

[Example 6]
The procedure was the same as in Example 3 except that water was added at a charge amount of 0.20% by mass based on the solid content of the resin of 100% by mass, the spinning temperature was 190 ° C., and the nozzle surface-cooling water distance was 30 cm. We obtained a three-dimensional network structure.

[Example 7]
A network structure was obtained in the same manner as in Example 5 except that the spinning temperature was 210° C., the single hole discharge rate was 1.0 g/min, and the take-up speed was 1.28 m/min.

[Comparative Example 1]
2.5% by mass of water was added to 100% by mass of the solid content of the resin, the single hole discharge amount was 0.9 g/min, the nozzle surface-cooling water distance was 18 cm, and the take-up speed was 0.52 m/min. A three-dimensional network structure was obtained in the same manner as in Example 1, except for the above.

[Comparative Example 2]
The procedure was the same as in Example 4 except that water was added at a charge amount of 0.02% by mass with respect to 100% by mass of the solid content of the resin, and drying was performed at 20 to 25 ° C. for 2 days without annealing. We obtained a three-dimensional network structure.

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

Table 1 shows the production conditions in Examples 1 to 7 and 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 multiple times is an average value.

The three-dimensional network structures obtained in Examples 1 to 7 were excellent in compression durability and compression recovery after heat compression. Furthermore, in Examples 1 to 6, the melt viscosity of the polymer during ejection was reduced, so a fine loop could be produced, and the surface and appearance quality were excellent.

The network structure obtained in Comparative Example 1 had a low weight-average molecular weight and poor recovery from compression after heat compression. Moreover, the network structure obtained in Comparative Example 1 was slightly yellowed. It is considered that this is influenced by the high water content of the three-dimensional network structure before annealing.

The network structures obtained in Comparative Examples 2 and 3 had a low crystal melting enthalpy, and were inferior in compression durability and compression recovery after heat compression.

Claims (6)

an apparent density of 0.005 g/cm ³ to 0.30 g/cm ³ ;
The thickness is 10 mm to 100 mm,
linear fibers, the linear fibers have a fiber diameter of 0.2 mm to 2.0 mm,
Polybutylene adipate terephthalate having a crystal melting enthalpy of 16 J/g or more and 30 J/g or less and a weight-average molecular weight of 35000 or more and 150000 or less is contained in 98% by mass or more of the linear fiber 100% by mass. contains in
A biodegradable three-dimensional network structure characterized in that the polybutylene adipate terephthalate contains an adipic acid component, a terephthalic acid component, and a butanediol component in a total amount of 99 mol% or more in 100 mol% of all components . . The biodegradable three-dimensional network structure according to claim 1, wherein the linear fibers form a three-dimensional random loop structure. 3. The biodegradable three-dimensional network structure according to claim 1, which is used as a cushion. The biodegradable three-dimensional network structure according to any one of claims 1 to 3 , wherein the linear fibers have a melting point of 100°C or higher and 120°C or lower. The biodegradable three-dimensional network structure according to any one of claims 1 to 4 , wherein the linear fibers have a hollow cross-sectional shape. 6. The biodegradable three-dimensional network structure according to claim 5 , wherein the linear fibers have a hollowness of 1% or more and 30% or less.

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