Method for producing three-dimensional filament assembly

Abstract

The present invention relates to a method for producing a three-dimensional filament assembly wherein an average radius of curvature of loop-shaped filaments is between 5 mm and 15 mm, both inclusive, the method comprising: a molten filament group formation step for extruding a molten thermoplastic resin from a nozzle portion in which a large number of nozzle holes are formed at predetermined intervals, to form a molten filament group; a loop formation step for causing the molten filament to form a loop and causing adjacent molten filaments to come into contact and become entangled with each other; a thickness adjustment step for reducing the thickness of the molten filament group to the distance between a pair of guide members; a cooling solidification step for cooling and solidifying the molten filament group of which the thickness has been adjusted; and a cutting step for cutting the cooled and solidified filament group to obtain a rectangular parallelepiped three-dimensional filament assembly. The formation interval of the nozzle holes is between 0.6 times and 2 times the average radius of curvature of the filaments, both inclusive.

Description

Method for manufacturing three-dimensional filament bonded body

[0001] The present invention relates to a method for producing a three-dimensional filament assembly that can be used as a cushion material for mattresses, pillows, and the like.

[0002] As a cushioning material that overcomes the drawbacks of metal springs and urethane foam, which require a lot of effort to recycle, attention has been drawn to three-dimensionally fused filament-bonded filaments (three-dimensional network structures) made of thermoplastic elastomers. This cushioning material has the advantages of being easy to recycle, not becoming stuffy, and being washable.

[0003] As a method for manufacturing a three-dimensional combined filament body, for example, Patent Document 1 discloses a manufacturing method in which a group of molten filaments (a linear aggregate of molten thermoplastic resin) consisting of a large number of molten filaments flowing down vertically is dropped into cooling water, and molten filament loops are formed by the buoyancy of the water, and at the same time, the molten filaments are brought into contact with each other due to the bending that occurs when the loops are formed, and the contact points are fused and bonded to form a three-dimensional combined filament body, and in order to keep the thickness of the three-dimensional combined filament body constant, a pair of chutes are provided that are inclined from both ends of the group of molten filaments in the thickness direction toward the center of the group of molten filaments in the thickness direction.

[0004] Japanese Patent Application Laid-Open No. 2004-218116

[0005] However, in the manufacturing method disclosed above, when the molten filaments are received by a chute to form loops, adjacent molten filaments may interfere with each other, resulting in uneven loop shapes and the generation of locally low filament density portions. If the filament density becomes low and holes with a diameter of, for example, 30 mm or more are formed on the surface of the three-dimensionally bound filaments, the three-dimensionally bound filaments may be prone to breakage from those portions.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for reliably producing a three-dimensional filament bonded body having a uniform filament density on both sides in the thickness direction and being less likely to break.

[0007] In order to achieve the above object, a method for producing a three-dimensional combined filament according to one aspect of the present invention is a method for producing a three-dimensional combined filament in which a large number of loop-shaped filaments are three-dimensionally combined to form a rectangular parallelepiped shape, and the average radius of curvature of the loop-shaped filaments on both side surfaces in the thickness direction is in the range of 5 mm to 15 mm, the method comprising the steps of: extruding molten thermoplastic resin downward from a nozzle portion in which a large number of nozzle holes are formed at predetermined intervals and the axial direction of the nozzle holes is in the up-down direction, thereby forming a molten filament group consisting of a large number of straight molten filaments; and receiving both thickness direction ends of the extruded molten filament group, which are perpendicular to the up-down direction when the three-dimensional combined filaments are formed, by a pair of guide members facing each other in the thickness direction and having inclined surfaces inclined downwards toward each other in the thickness direction. a thickness adjusting step of supplying cooling water to the inclined surfaces of the pair of guide members, and moving the looped molten filaments downward along the inclined surfaces while solidifying them, thereby thinning the thickness of the group of molten filaments to the distance between the pair of guide members; a cooling and solidifying step of drawing the group of molten filaments whose thickness has been adjusted into a cooling water tank installed below the pair of guide members by a pair of conveyors provided below the pair of guide members and facing each other in the thickness direction, and cooling and solidifying the group of molten filaments; and a cutting step of cutting the group of cooled and solidified filaments perpendicular to the direction of movement to form a three-dimensional combined filament body having a rectangular parallelepiped shape, wherein the formation interval of the nozzle holes is in a range of 0.6 to 2 times the average radius of curvature of the filaments.

[0008] The average radius of curvature of the filaments is a value measured by the measurement method in the examples described later.

[0009] The manufacturing method of the above configuration may further include a drying step of drying the cooled and solidified filament group, and a cutting step of cutting the dried filament group perpendicular to the moving direction to form a rectangular parallelepiped-shaped three-dimensional filament bond.

[0010] In the manufacturing method having the above configuration, it is preferable that the inclination angle of the inclined surfaces of the pair of guide members is in the range of 10° to 40° with respect to the horizontal plane.

[0011] In the manufacturing method having the above configuration, it is preferable that the average distance from the lower surface of the nozzle portion to the inclined surface of the guide member is in the range of 100 mm to 350 mm, where "average distance" refers to the average distance from each nozzle hole to the inclined surface.

[0012] In the manufacturing method having the above configuration, it is preferable that the pressure at which the molten thermoplastic resin is supplied to the nozzle portion is in the range of 4.5 MPa or more and 13.0 MPa or less.

[0013] In this specification, unless otherwise specified, the word "to" means that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0014] According to the method for producing a three-dimensional filament bonded body of the present invention, it is possible to reliably produce a three-dimensional filament bonded body having a uniform filament density on both sides in the thickness direction and being less likely to break.

[0015] 1 is a process diagram showing one embodiment of a manufacturing method according to the present invention. FIG. 2 is a conceptual diagram of a manufacturing apparatus for a three-dimensionally bound filament body. FIG. 3 is a cross-sectional view of the manufacturing apparatus shown in FIG. 2 along line A-A. FIG. 4 is a bottom view and a partially enlarged view of a nozzle section of the manufacturing apparatus shown in FIG. 2. FIG. 5 is a perspective view of a chute of the manufacturing apparatus shown in FIG. 2. FIG. 6 is a side view showing the movement of molten filaments extruded from the nozzle section. FIG. 7 is a plan view showing the movement of molten filaments extruded from the nozzle section. FIG. 8 is a process diagram for measuring the average radius of curvature of filaments on the surface of a three-dimensionally bound filament body. FIG. 9 is an example of an image of the surface (bottom surface) of a measurement sample transferred onto transfer paper.

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the terms "thickness direction," "left-right direction," and "feed direction" refer to the thickness direction, left-right direction, and feed direction shown in the drawings.

[0017] FIG. 1 shows a process diagram of a method for producing a three-dimensional filament bonded body (hereinafter, sometimes simply referred to as a "bonded body") TDF according to one embodiment of the present invention, FIG. 2 shows a conceptual diagram of a manufacturing apparatus for the bonded body TDF, and FIG. 3 shows a cross-sectional view of the manufacturing apparatus shown in FIG. 2 along line A-A.

[0018] (Molten filament group molding process) In the molten filament group molding process, a number of nozzle holes 17a (shown in Figure 4) are formed at predetermined intervals, and molten thermoplastic resin is extruded downward from the nozzle section 17, which is installed so that the axial direction of the nozzle holes 17a is in the vertical direction, to mold a molten filament group MF consisting of a number of straight molten filaments.

[0019] 2 and 3 , the molten filament supply section 10 includes a pressure melting section (extruder) 11 and a filament discharge section (die) 12. The pressure melting section 11 includes a cylinder 11a, a screw 14 rotatably housed within the cylinder 11a, a screw motor 15 that drives the screw 14, a heater 16 that heats the cylinder 11a, a material input section (hopper) 13 for inputting thermoplastic resin into the cylinder 11a, and multiple temperature sensors (not shown). The thermoplastic resin supplied from the material input section 13 is heated and melted by the heater 16 and transported forward by the screw 14.

[0020] A cylinder outlet 11b is formed at the front end of the cylinder 11a for discharging the thermoplastic resin toward the filament discharge section 12. The heating temperature of the heater 16 is controlled based on a detection signal from a temperature sensor provided in the molten filament supply section 10, for example.

[0021] The filament discharge section 12 includes a nozzle section 17, a die heater 18, and a plurality of temperature sensors (not shown). A guide channel 12a is formed inside the filament discharge section 12 to guide the molten thermoplastic resin discharged from the cylinder outlet 11b to the nozzle section 17.

[0022] As shown in FIG. 4, the nozzle section 17 is a thick metal plate having a substantially rectangular parallelepiped shape in which a large number of nozzle holes 17a are formed, and is provided below the filament discharge section 12, which corresponds to the most downstream portion of the guide channel 12a.

[0023] There are no particular limitations on the cross-sectional shape of the nozzle holes 17a perpendicular to the axial direction, and they may be perfect circles, ellipses, or polygons. There are also no particular limitations on the inner diameter (maximum diameter) of the nozzle holes 17a, but a range of 0.5 mm to 5 mm is generally preferred. The arrangement pattern of the nozzle holes 17a can be adjusted as appropriate.

[0024] The formation interval d of adjacent nozzle holes 17a (shown in the enlarged view of the circled frame in FIG. 4) is appropriately determined taking into consideration the average radius of curvature r (shown in FIG. 7) of the loop filaments of the combined body TDF to be obtained. Specifically, the formation interval d of the nozzle holes 17a is set to a range of 0.6 to 5 times the average radius of curvature r of the loop filaments to be obtained on both side surfaces in the thickness direction of the combined body TDF. The formation interval d of the nozzle holes 17a is preferably set to a range of 0.6 to 1.5 times the average radius of curvature r.

[0025] A plurality of die heaters 18 (six die heaters 18a to 18f in the example shown in FIG. 3) are provided in the left-right direction and heat the guide channel 12a of the filament discharge section 12. The heating temperature of the die heater 18 is controlled based on a detection signal from a temperature sensor (not shown) provided in the filament discharge section 12, for example.

[0026] Examples of thermoplastic resins that can be used as the material for the binder TDF include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polyamide resins such as nylon 66, polyvinyl chloride resin, and polystyrene resin, as well as thermoplastic elastomers such as styrene elastomers, vinyl chloride elastomers, olefin elastomers, urethane elastomers, polyester elastomers, nitrile elastomers, polyamide elastomers, and fluorine elastomers.

[0027] The thermoplastic resin supplied from the material input unit 13 is heated and melted in the cylinder 11a, and is extruded by the screw 14, and is supplied as molten thermoplastic resin from the cylinder outlet 11b to the guide channel 12a of the filament discharge unit 12. Thereafter, molten filaments are discharged downward from each of the many nozzle holes 17a of the nozzle unit 17, and a molten filament group MF is formed.

[0028] The supply pressure of the molten thermoplastic resin to the nozzle portion 17 may be appropriately determined depending on the inner diameter and number of the nozzle holes 17a, the shape and size of the molten filament group MF, etc., but is generally preferably in the range of 4.5 MPa to 13.0 MPa. By keeping the supply pressure of the molten thermoplastic resin to the nozzle portion 17 in this range, a large number of linear molten filaments can be continuously and stably supplied.

[0029] (Loop Forming Process) In the loop forming process, both thickness direction ends of the molten filament group MF extruded from the nozzle portion 17 are received by the inclined surfaces 53 a, 53 b of a pair of chutes 5 a, 5 b spaced apart in the thickness direction and facing each other, causing the molten filaments to form loops and contact and entangle adjacent molten filaments with each other. Furthermore, the molten filaments in the thickness direction central portion of the molten filament group MF that do not contact the chutes abut on the water surface of the cooling water tank 23, causing the buoyancy of the water to form loops of the molten filaments, and simultaneously causing the molten filaments to contact each other due to bending during loop formation, causing the contact points to be fusion-bonded and then cooled and solidified to form a three-dimensional bonded body.

[0030] As shown in FIGS. 6 and 7 , the molten filaments extruded from the nozzle portion 17 and received by the inclined surface 53b of the chute 5b form loops. Here, the average radius of curvature r of the loop filaments (shown in FIG. 7 ) is set to a range of 5 mm to 15 mm. When the average radius of curvature r of the loop filaments is set within this range, the filament density on both side surfaces in the thickness direction of the combined body TDF becomes uniform, making the combined body TDF less likely to break. The average radius of curvature r of the loop filaments can be controlled by the formation interval d of the nozzle holes 17a (shown in FIG. 4 ). Specifically, as described above, the formation interval d of the nozzle holes 17a is set to a range of 0.6 to 5 times the average radius of curvature r of the loop filaments to be obtained. When the formation interval d of the nozzle holes 17a and the average radius of curvature r of the loop filaments satisfy this relationship, the molten filaments moderately interfere with each other in the inclined direction and the left-right direction on the inclined surfaces 53a and 53b of the chutes 5a and 5b, resulting in an appropriate number of contacts and entanglements between the molten filaments.

[0031] Furthermore, as described below, the degree of interference of the molten filaments in the inclined direction of the chutes 5a and 5b can be adjusted by the speed difference between the speed at which the pair of conveyors 24a and 24b pull the molten filament group MF from the chutes 5a and 5b and the speed at which the molten filament group MF is supplied to the chutes 5a and 5b, making it possible to achieve an appropriate number of contacts and entanglements between the molten filaments.

[0032] As shown in FIG. 5 , a pair of chutes 5a, 5b are arranged opposite each other at a predetermined distance in the thickness direction. Specifically, the pair of chutes 5a, 5b are arranged symmetrically with respect to an imaginary plane including the thickness direction and the left-right direction. Each pair of chutes 5a, 5b has inclined portions 51a, 51b that extend toward the opposing chute as they move downstream in the supply direction of the molten filament group MF, and parallel portions 52a, 52b that connect to the downstream ends of the inclined portions 51a, 51b and extend parallel to the supply direction of the molten filament group MF and downstream in the supply direction. The inclined portions 51a, 51b and the parallel portions 52a, 52b are integrally formed. The materials for the inclined portions 51a, 51b and the parallel portions 52a, 52b are not particularly limited as long as they have the required heat resistance, rust prevention, processability, etc. Examples of materials for the inclined portions 51a, 51b and the parallel portions 52a, 52b include metals such as stainless steel, aluminum, and copper, and heat-resistant resins such as polycarbonate. Among these, metal materials such as stainless steel and copper are preferably used.

[0033] The inclined portions 51 a, 51 b receive both ends of the molten filament group MF in the thickness direction and guide them toward the center of the molten filament group MF in the thickness direction. The parallel portions 52 a, 52 b adjust the thickness of the molten filament group MF and, ultimately, the thickness of the combined body TDF. The upper surfaces of the inclined portions 51 a, 51 b form inclined surfaces 53 a, 53 b.

[0034] The inclination angle θ (shown in FIG. 5) of the inclined surfaces 53a, 53b of the pair of chutes 5a, 5b relative to the horizontal plane is preferably in the range of 10° to 40°. By setting the inclination angle θ in this range, the filament density on both sides of the combined body TDF in the thickness direction can be set within a desired range.

[0035] The average distance from the lower surface of the nozzle portion 17 to the inclined surfaces 53a and 53b of the pair of chutes 5a and 5b is preferably in the range of 100 mm to 350 mm. When the average distance is in this range, it becomes easier to control the radius of curvature r of the loop-shaped filaments within a desired range.

[0036] The pair of chutes 5a, 5b may have a continuous hydrophilic layer on the surfaces of the inclined surfaces 53a, 53b and the opposing inner surfaces of the parallel portions 52a, 52b. The contact angle of the hydrophilic layer with water is preferably 30° or less, more preferably 10° or less. Note that the hydrophilic layer only needs to be formed on at least the inclined surfaces 53a, 53b, and does not necessarily need to be formed on the opposing inner surfaces of the parallel portions 52a, 52b. However, from the viewpoint of forming a more uniform bonded body TDF, it is desirable that the hydrophilic layer be formed at least up to the upper portion exposed above the water surface of the stored water in the cooling water tank 23 (the middle portion of the parallel portion in the manufacturing apparatus shown in FIGS. 2 and 3 ).

[0037] 2 and 3, cooling water supply units 4a, 4b are provided above the upper ends of chutes 5a, 5b, extending over substantially the entire width of chutes 5a, 5b in the left-right direction. The cooling water supply units 4a, 4b continuously supply cooling water evenly to inclined surfaces 53a, 53b of chutes 5a, 5b. The cooling water supplied to chutes 5a, 5b by the cooling water supply units 4a, 4b may be water supplied from outside the manufacturing apparatus 1, or a portion of the cooling water in cooling water tank 23.

[0038] (Thickness Adjustment Process) In the thickness adjustment process, both ends in the thickness direction of the molten filament group MF, which is made up of a large number of straight molten filaments and discharged from the nozzle portion 17, are received by the inclined surfaces 53 a, 53 b of the pair of chutes 5 a, 5 b and then guided toward the center in the thickness direction by the chutes 5 a, 5 b, thereby adjusting the thickness of the molten filament group MF and, ultimately, the thickness of the combined body TDF. That is, the thickness of the molten filament group MF is controlled by the distance in the thickness direction between the parallel portions 52 a, 52 b (shown in FIG. 5 ) of the pair of chutes 5 a, 5 b.

[0039] The thickness-wise ends of the molten filament group MF are received by the inclined surfaces 53a, 53b of a pair of chutes 5a, 5b and then guided toward the center in the thickness direction, while the thickness-wise center of the molten filament group MF abuts the water surface of the cooling water tank 23, so that the filament density on both thickness-wise sides of the molten filament group MF (and thus the combined body TDF) is higher than that in the thickness-wise center.

[0040] (Cooling and solidifying process) In the cooling and solidifying process, the molten filament group MF is drawn into a cooling water tank 23 installed below the pair of chutes 5a and 5b by a pair of conveyors 24a and 24b that are provided below the pair of chutes 5a and 5b and face each other in the thickness direction, while the thickness is adjusted, and the molten filament group MF is cooled and solidified. The separation distance in the thickness direction between the pair of conveyors 24a and 24b is set to be approximately the same as the separation distance in the thickness direction between the parallel portions 52a and 52b of the pair of chutes 5a and 5b.

[0041] The draw-in speed of the molten filament group MF by the pair of conveyors 24a, 24b is set slower than the discharge (supply) speed of the molten filament group MF discharged from the filament discharge section 12. A loop of the molten filament is formed by setting the draw-in speed of the pair of conveyors 24a, 24b slower than the supply speed of the molten filament group MF. There are no particular limitations on the ratio of the supply speed of the molten filament group MF from the filament discharge section 12 to the draw-in speed by the pair of conveyors 24a, 24b, but typically, a range of 3:1 to 7:1 is preferable.

[0042] The cooling water tank 23 is a tank for storing cooling water, and a pair of conveyors 24a, 24b and a plurality of transport rollers 25a to 25h are disposed inside the cooling water tank 23. The pair of conveyors 24a, 24b and the plurality of transport rollers 25a to 25h are driven by a drive motor (not shown). Parts of the pair of conveyors 24a, 24b may be exposed above the water surface of the cooling water tank.

[0043] The molten filament group MF drawn into the cooling water tank 23 by the pair of conveyors 24a, 24b is transported within the cooling water tank 23 by a plurality of transport rollers 25a to 25h. During this time, the molten filament group MF is cooled by the cooling water and then discharged out of the cooling water tank 23.

[0044] (Drying step) In the drying step, the cooled and solidified combined TDF is dried as needed. The drying method is not particularly limited, and any conventionally known drying method can be used. For example, heat drying or hot air drying can be used.

[0045] (Cutting Step) In the cutting step, the dried combined body TDF is cut in a direction perpendicular to the moving direction as needed to form a combined body in the shape of a rectangular parallelepiped. The cutting interval of the combined body TDF may be appropriately determined depending on the intended use of the combined body TDF, such as a mattress, cushion, or pillow. There are no particular limitations on the means for cutting the combined body TDF, and any conventionally known cutting means may be used.

[0046] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0047] Examples 1 to 15 and Comparative Examples 1 to 10: Combined bodies TDF were produced using the production apparatus shown in Figures 2 and 3. The average radius of curvature of the filaments on the surface in the thickness direction was measured using the method described below, and the filament shape appearing on the surface of the combined body TDF and the number and state of contact and entanglement points between the filaments were visually observed. Specific production conditions were as follows: Resin: Polyester-based thermoplastic elastomer Nozzle holes: Inner diameter 1.2 mm, forming interval 12 mm, staggered arrangement Heating temperature of nozzle part: See Table 1 Resin pressure of nozzle part: See Table 1 Inclination angle of chute: See Table 1 Distance from bottom of nozzle to inclined surface: See Table 1 Supply speed of molten filament group MF to chute: 2500 mm / min Pull-in speed of molten filament group MF by conveyor: 500 mm / min

[0048] (Measurement of the Average Radius of Curvature of Filaments) Figure 8 shows a process diagram for measuring the average radius of curvature of the filaments of the combined TDF. First, the combined TDF was cut into squares with sides of 20 cm in plan view using a running saw to prepare 10 measurement samples SP (10 to 15 filament arcs could be traced on each measurement sample SP). The measurement samples SP were placed on a substrate 61 with a larger area than the measurement samples SP and on which a water-based paint 60 had been uniformly applied in advance (Figure 8(a)). Next, a square plate 62 with sides of 30 cm was placed on the measurement samples SP, and a 30 kg weight 63 was placed on the plate 62 (Figure 8(b)). The plate was then left with the weight 63 in place for 30 seconds, and the water-based paint 60 was then applied to the underside of the measurement samples SP (Figure 8(c)).

[0049] Next, the measurement sample SP is placed on a transfer paper P placed on a square plate 64 with sides of 30 cm, with the side coated with the water-based paint 60 facing downwards (FIG. 8(d)). Then, a square plate 62 with sides of 30 cm is placed on the measurement sample SP, and a 30 kg weight 63 is placed on the plate 62 (FIG. 8(e)). The plate is then left with the weight 63 placed for 30 seconds (FIG. 8(f)), and the unevenness of the underside of the measurement sample SP is transferred onto the transfer paper P (FIG. 8(g)).

[0050] FIG. 9 shows an example of a surface (lower surface) image of the measurement sample SP transferred onto transfer paper P. The surface image shows multiple arcs that constitute part of the looped filament. From these multiple arcs, arcs bent by 90° or more are selected and the radius of curvature r is measured. The radius of curvature r for each arc is the radius of the largest circle inscribed in the arc. The average radius of curvature is the average value of the radii of curvature for 100 to 150 arcs of the filament.

[0051]

[0052] Examples 16 to 30, Comparative Examples 11 to 20 A combined body TDF was produced using the production apparatus shown in Figure 2, and the average radius of curvature of the filaments on the surface in the thickness direction was measured using the method described above. The filament shape appearing on the surface of the combined body TDF and the number and state of contact and entanglement points between the filaments were also visually observed. Specific production conditions were as follows: Resin: Polyester-based thermoplastic elastomer Nozzle hole: Inner diameter 0.6 mm, forming interval 8 mm, staggered arrangement Heating temperature of nozzle part: See Table 2 Resin pressure of nozzle part: See Table 2 Inclination angle of chute: See Table 2 Distance from bottom of nozzle to inclined surface: See Table 2 Supply speed of molten filament group MF to chute: 2500 mm / min Pull-in speed of molten filament group MF by conveyor: 500 mm / min

[0053]

[0054] As is clear from Tables 1 and 2, the bonded TDFs produced by the manufacturing methods of Examples 1 to 30 had many filament loops appearing on both sides in the thickness direction (high filament density) and many fusion points between adjacent filaments.

[0055] In contrast, the combined TDFs produced by the manufacturing methods of Comparative Examples 1 to 4 and 11 to 14 had nozzle hole formation intervals that were too large relative to the average radius of curvature of the filaments, resulting in many filament loops appearing on the surface of the combined TDFs, but few fusion points with adjacent filaments, and therefore did not have sufficient strength. Furthermore, the combined TDFs produced by the manufacturing methods of Comparative Examples 5 to 10 and 15 to 20 had nozzle hole formation intervals that were too small relative to the average radius of curvature of the filaments, resulting in few filament loops appearing on the surface of the combined TDFs, and the filament shapes were very random, resulting in partial depressions with inner diameters of 30 mm or more on the surface of the combined TDFs.

[0056] According to the method for producing a three-dimensional filament bonded body of the present invention, it is possible to reliably produce a three-dimensional filament bonded body having a uniform filament density on both sides in the thickness direction and being less likely to break.

[0057] REFERENCE SIGNS LIST 1 Manufacturing device 4a, 4b Cooling water supply section 5a, 5b Chute (guide member) 10 Melted filament supply section 17 Nozzle section 17a Nozzle hole 51a, 51b Inclined section 52a, 52b Parallel section 53a, 53b Inclined surface d Formation interval of nozzle hole r Radius of curvature of filament MF Melted filament group TDF Three-dimensional bonded filament

Claims

1. A method for producing a three-dimensional bound filament body in which a large number of loop-shaped filaments are bound in three dimensions to form a rectangular parallelepiped shape, and the average radius of curvature of the loop-shaped filaments on both side surfaces in the thickness direction is in the range of 5 mm to 15 mm, comprising: a molten filament group forming step of extruding molten thermoplastic resin downward from a nozzle portion in which a large number of nozzle holes are formed at predetermined intervals and the axial direction of the nozzle holes is set in the up-down direction to form a molten filament group consisting of a large number of straight molten filaments; a loop forming step of receiving both thickness direction ends of the extruded molten filament group when it becomes a filament three-dimensional bound body with a pair of guide members that face each other in the thickness direction and have inclined surfaces that incline toward each other in the thickness direction as they move downward, forming loops in the molten filaments and contacting and entangling adjacent molten filaments with each other; and a thickness adjusting step of supplying cooling water to the inclined surfaces of the pair of guide members, and moving the looped molten filaments downward along the inclined surfaces while solidifying them, thereby thinning the thickness of the molten filament group to the distance between the pair of guide members. a cooling and solidification process in which a group of molten filaments having an adjusted thickness is drawn into a cooling water tank installed below the pair of guide members by a pair of conveyors facing each other in the thickness direction and installed below the pair of guide members, and cooled and solidified; wherein the nozzle hole formation interval is in the range of 0.6 to 2 times the average radius of curvature of the filaments.

2. A method for producing a three-dimensional filament assembly as claimed in claim 1, further comprising: a drying step for drying the cooled and solidified filament assembly; and a cutting step for cutting the dried filament assembly perpendicular to the moving direction to form a rectangular parallelepiped three-dimensional filament assembly.

3. A method for producing a three-dimensional filament assembly according to claim 1 or 2, wherein the inclination angle of the inclined surfaces of the pair of guide members is in the range of 10° to 40° with respect to the horizontal plane.

4. A method for producing a three-dimensional filament assembly according to any one of claims 1 to 3, wherein the average distance from the lower surface of the nozzle portion to the inclined surface of the guide member is in the range of 100 mm or more and 350 mm or less.

5. A method for producing a three-dimensional filament assembly according to any one of claims 1 to 4, wherein the pressure at which the molten thermoplastic resin is supplied to the nozzle portion is in the range of 4.5 MPa or more and 13.0 MPa or less.

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