Three-dimensional net-like structure, and method and device for producing three dimensional net-like structure

A method of and an apparatus for manufacturing a three-dimensional netted structure which is capable of rendering it unnecessary to carry out a finishing operation in a later stage, improving the degree of straightness of the side surfaces of the netted structure, meeting a demand for finishing the netted structure to modified shapes, and improving the durability of the netted structure. A three-dimensional netted structure (1) using thermoplastic resin as a raw material or a main raw material is characterized by a three-dimensional plate type netted structure, in which a plurality of filaments are helically and randomly entangled and partly and thermally bonded together. The density of any of at least three surfaces or four surfaces on the outer periphery of the three-dimensional netted structure is preferably relatively higher than the density of the other portion excluding these surfaces, and flaked or chipped PET bottles are used as a raw material or a main raw material for thermoplastic resin, such PET bottles being directly crushed and then melted to provide flakes, suiting to recycling promoting age, working well in waste disposal cost reduction, the uses of the three-dimensional netted structure (1) including, chiefly, shock absorbing materials, cushioning materials, and sound-absorbing materials.

FIELD OF THE INVENTION

This invention relates to a three-dimensional netted structure used for a cushioning material and the like, and a method of and an apparatus for manufacturing the same.

BACKGROUND OF THE INVENTION

Known methods of manufacturing a void-carrying three-dimensional netted structure include a method disclosed in Japanese Patent Publication KOKOKU No. S50-39185, or a method disclosed in Japanese Patent Laid-Open KOKAI No. S60-11352, etc., which is adapted to manufacture resin cotton on which polyester fibers are bonded with a bonding agent made of, for example, a rubber-based material. There are also methods of or apparatuses for manufacturing a void-carrying three-dimensional netted structure by entangling resin threads by endless belts, and such methods or apparatuses include the invention disclosed in Japanese Patent Laid-Open KOKAI No. H11-241264, etc.

However, the demands for a product of such a three-dimensional netted structure have been diversified. It is necessary that each of netted structures manufactured be finished to one of different shapes by cutting or molding the netted structures to demanded shapes in a later stage of the manufacturing stage. This causes a product finishing operation to become very complicated.

A three-dimensional netted structure manufactured by a prior art method becomes low in density in some cases. Since both surface portions of a bundle contact belt conveyors, outer surfaces of the bundle are substantially flattened. However, left and right end surfaces of the bundle have an irregular, helical shape, and side surfaces thereof have a laterally wavy non-straight shape.

The endless belts mentioned above by which a resin threads are entangled is liable to be damaged due to the heat, etc., so that there is a fear of encountering a problem concerning the durability of the endless belts.

Therefore, the present invention provides a method of and an apparatus for manufacturing a three-dimensional netted structure, capable of rendering it unnecessary to carry out a finishing operation in a later stage, improving the degree of straightness of the side surfaces of the netted structure, meeting a demand for finishing the netted structure to modified shapes, and improving the durability of the netted structure.

SUMMARY OF THE INVENTION

In view of these various problems, the invention is a three-dimensional netted structure manufactured by preparing a thermoplastic resin as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, partly and thermally bonded filaments by extrusion molding; and cooling the resultant filaments with water so as to obtain a netted structure having sparse and dense portions arranged alternately in the material extruding direction. This enables the netted structure to be applied to a cushioning material and the like which is made possible to be hung at a sparse portion thereof on a hook.

The invention is a three-dimensional netted structure manufactured by preparing a thermoplastic resin as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, partly and thermally bonded filaments by extrusion molding; and cooling the resultant filaments with a liquid so as to obtain a netted structure having hollow portions arranged in the material extruding direction. This enables the hollow portions to be utilized effectively by inserting other members therein or by using the hollow portions in a different manner, and the netted structure to be thereby applied to various uses.

The invention is a three-dimensional netted structure manufactured by preparing a thermoplastic resin as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, partly and thermally bonded filaments by extrusion molding; and cooling the resultant filaments with a liquid so as to obtain a sheet having a percentage of void of substantially zero in the material extruding direction. This enables the soundproofing and shock absorbing performance of the sheet to be improved.

The invention is a three-dimensional netted structure manufactured by preparing a thermoplastic resin as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, partly and thermally bonded filaments by extrusion molding; and cooling the resultant filaments with a liquid so as to obtain a netted structure having not smaller than two separable regions. This enables the difficulty, which was encountered in a related art netted structure of this kind, in recycling a complex resin and the like to be overcome by providing the netted structure with not smaller than two separable regions.

The invention is a three-dimensional netted structure manufactured by preparing a thermoplastic resin as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, partly and thermally bonded filaments by extrusion molding; and cooling the resultant filaments with a liquid so as to obtain an insulating material or a sound absorbing material. This enables the netted structure to be used as a building material, an interior finishing material for automobiles, and materials for similar purposes.

The invention is a three-dimensional netted structure manufactured by preparing a thermoplastic resin as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, partly and thermally bonded filaments by extrusion molding; cooling the resultant filaments with a liquid; and applying a fire-resistant material to the cooled filaments or enclosing the cooled filaments with the same material or adding the same material to the cooled filaments. This enables the reliability of an interior heat insulating material, an exterior heat insulating material, an interior finishing material for a side wall and an interior finishing material for automobiles to be improved.

The invention is a three-dimensional netted structure manufactured by preparing a thermoplastic resin as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, party and thermally bonded filaments by extrusion molding; and cooling the resultant filaments with a liquid so as to obtain a seedbed for planting trees on a roof. This enables the recycling of the seedbed to be done, and the planting of trees on a roof to be promoted.

The invention is a three-dimensional netted structure manufactured by preparing a thermoplastic resin as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, partly and thermally bonded filaments by extrusion molding; and cooling the resultant filaments with a liquid so as to obtain a gardening cushioning material. This enables the netted structure to be used instead of a wooden trellis, and the durability thereof to be improved.

The invention is a three-dimensional netted structure manufactured by preparing a thermoplastic resin as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, partly and thermally bonded filaments by extrusion molding; and cooling the resultant filaments with a liquid so as to obtain a netted structure having polyhedral or miscellaneously shaped side surfaces.

The invention is a three-dimensional netted structure manufactured by preparing a regenerated thermoplastic resin, especially, polyethylene terephthalate as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, partly and thermally bonded filaments by extrusion molding; and cooling the resultant filaments with a liquid so as to obtain a recycled netted structure. This enables the recovery of polyethylene terephthalate bottles, etc. to be promoted.

The invention is a three-dimensional netted structure manufactured by preparing a brittleness-causing raw material-containing thermoplastic resin as a raw material or a main raw material; forming the resin into a plurality of helically and randomly entangled, partly and thermally bonded filaments by extrusion molding, and cooling the resultant filaments with a liquid so as to obtain a netted structure capable of being brittle fractured by applying an external force thereto. This enables a shock occurring due to the collision of a vehicle to break the texture of the three-dimensional netted structure, so that damage to a vehicle due to the collision thereof can be prevented.

The invention is an apparatus for manufacturing a three-dimensional netted structure which is obtained by extruding molten filaments of a thermoplastic resin, a raw material or a main raw material downward from a die having a plurality of holes; having the filaments drop naturally between partly-submerged drawing-down units; when a three-dimensional netted structure is manufactured by drawing said filaments between said drawing-down units at a speed lower than a filament dropping speed, a distance between said drawing-down units being set smaller than a width of an assembly of said extruded filaments, said drawing-down units being arranged so that at least three or four surfaces of the assembly of said filaments contact said drawing-down units before or after said drawing-down units are submerged. This renders it unnecessary to carry out a finishing operation in a later stage, and enables the degree of straightness of the side surfaces of the netted structure to be heightened.

The invention is an apparatus for manufacturing a three-dimensional netted structure which is obtained by extruding molten filaments of a thermoplastic resin, a raw material or a main raw material downward from a die having a plurality of holes; having the filaments drop naturally between partly-submerged rollers; and drawing said filaments between the rollers at a speed lower than a filament dropping speed, a distance between said rollers being set smaller than a width of an assembly of said extruded filaments, at least one surface of the assembly of said filaments contacting said rollers before or after said rollers are submerged. This enables the simplicity of the apparatus and the easiness of designing the apparatus to be attained.

The invention is an apparatus for manufacturing a three-dimensional netted structure which is obtained by extruding molten filaments of a thermoplastic resin, a raw material or a main raw material downward from a die having a plurality of holes; having the filaments drop naturally between partly-submerged, slidable surface-carrying plate members a distance between which is set so as to decrease gradually in the downward direction; and drawing said resultant filaments between the plate members at a speed lower than a filament dropping speed, a distance between lower portions of the plate members being set smaller than a width of an assembly of said extruded filaments, at least one surface of the assembly of the filaments contacting the plate members before or after the plate members are submerged. This enables the miniaturization of the apparatus to be attained by reducing or omitting movable parts.

The invention is an apparatus for manufacturing a three-dimensional netted structure which is obtained by extruding molten filaments of a thermoplastic resin, a raw material or a main raw material downward from a die having a plurality of holes; having the filaments drop naturally between partly submerged drawing-down units; and drawing said filaments between said drawing-down units at a speed lower than a filament dropping speed, a distance between said drawing-down units being set smaller than a width of an assembly of said extruded filaments, at least one surface of the assembly of said filaments contacting the drawing-down units before or after said drawing-down units are submerged, a cross section of outer circumferential members of the drawing-down units being set to modified shapes. This enables an operation in a later stage to be omitted.

The invention is an apparatus for manufacturing a three-dimensional netted structure which is obtained by extruding molten filaments of a thermoplastic resin, a raw material or a main raw material downward from a die having a plurality of holes; having the filaments drop naturally between partly-submerged drawing-down units; and drawing said filaments between said drawing-down units at a speed lower than a filament dropping speed, a distance between said drawing-down units being set smaller than a width of an assembly of said extruded filaments, at least one surface of the assembly of said filaments contacting said drawing-down units before or after said drawing-down units are submerged, said die being provided with a complex die which has not smaller than two chambers and a plural-hole-carrying mouthpiece, the molten filaments of a thermoplastic resin, a raw material or a main raw material being extruded downward from the holes of said mouthpiece via different passages isolated from one another by partitions. This enables a separable three-dimensional netted structure to be manufactured.

The invention is an apparatus for manufacturing a three-dimensional netted structure which is obtained by extruding molten filaments of a thermoplastic resin, a raw material or a main raw material downward from a die having a plurality of holes; having the filaments drop naturally between partly-submerged drawing-down units; and drawing said resultant filaments between said drawing-down units at a speed lower than a filament dropping speed, a distance between said drawing-down units being set smaller than a width of an assembly of said extruded filaments, at least one surface of the assembly of the filaments contacting the drawing-down units before or after the drawing-down units are submerged, the drawing-down units being provided with circumferentially moving members, which are provided at circumferences thereof with circumferentially extending metal nets or plate members. This enables the durability of the drawing-down units to be improved.

The invention is an apparatus for manufacturing a three-dimensional netted structure which is obtained by extruding molten filaments of a thermoplastic resin, a raw material or a main raw material downward from a die having a plurality of holes; having the filaments drop naturally between partly-submerged drawing-down units; and drawing said filaments between said drawing-down units at a speed lower than a filament dropping speed, a distance between said drawing-down units being set smaller than a width of an assembly of said extruded filaments, at least one surface of the assembly of the filaments contacting said drawing-down units before or after said drawing-down units are submerged, regions of a high density of holes and regions of a low density of holes being formed on a mouthpiece of said die. This enables the range of designing of the apparatus to be widened.

The invention is a method of manufacturing a three-dimensional netted structure, the method being applied to the inventions described.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown inFIGS. 1 and 2A, a three-dimensional netted structure1of the first mode of embodiment is a three-dimensional netted structure the characteristics of which reside in that the structure is a three-dimensional plate type netted structure formed out of a regenerated thermoplastic resin as a raw material or a main raw material, in which a plurality of filaments are helically and randomly entangled and partly and thermally bonded together and have two side surfaces, left and right end surfaces and upper and lower end surfaces. It is preferable that the density of surface-side portions of three surfaces out of the side surfaces of this three-dimensional netted structure be relatively higher than that of the portion exclusive of the mentioned surface-side portions. Namely, the three-dimensional netted structure1(refer toFIG. 2A) of the first mode of embodiment is three-surface-molded. In this structure, regions thereof which extend inward from the opposite surfaces thereof by a predetermined distance are molded to a high density, and the density of a region which extends in a central inner portion of the netted structure is set lower than the mentioned density. Thus, the remaining one surface of the structure has a non-straight extending surface. Therefore, this netted structure has an advantage in being not subjected to a process in a later stage. In short, a pair of surfaces of a large width and one side surface are forcibly molded by endless conveyors and the like which will be described later, and the edges of these surfaces are formed more beautifully than that of the other surface.

In this embodiment, flaked or chipped PET bottles are used as a raw material or a main raw material of the regenerated thermoplastic resin. The raw material is obtained by pulverizing PET bottles as they are, melting the pulverized products, and forming the molten product into flakes. This material is suited to the recycling promoting age. When the material is not a recycled product but a genuine product, the manufacturing cost per 1 m2of the netted structure increases double due to the dry crystallization of or the removal of waste from the material. The material used in this embodiment can exercise its power in the reduction of the product scrapping cost. However, this embodiment can also be applied to a thermoplastic resin and the like other than regenerated materials of this kind. For example, polyolefines, such as polyethylene, polypropylene, etc., polyesters, such as polyethylene terephthalate, etc. polyamides, such as nylon 66, etc, polyvinyl chloride, polystyrene, a copolymer and an elastomer obtained by copolymerizing these resins as base materials, a material obtained by blending these resins, and some other similar materials. The three-dimensional netted structure, is used mainly as a cushioning material, a shock absorbing material, a moisture absorbing material, a sound absorbing material (to be provided under a floor material, in an inner portion of a structure and inside a wall), a heat insulating material (inner and outer heat insulating purposes), a wall surface material, a roof gardening material, a concrete and mortar cracking preventing material, interior finishing material for automobiles, and has some other uses. This netted structure can also be applied to an inner portion of a double wall.

When a fire resistant material is mixed with the three-dimensional netted structure by holding the three-dimensional netted structure between nonwoven cloths or by attaching such cloths thereto, and applying fire resistant paint to the netted structure, so as to give fire resistance to the three-dimensional netted structure, the resultant netted structure becomes more preferable as a heat insulating building material, a sound absorbing building material and the like.

This first mode of embodiment is molded so as to have a substantially uniform density at an inner portion thereof. The apparent density of this embodiment is preferably 0.02 to 0.9 g/cm3(corresponding to a percentage of void of 36 to 98.4%), and specially preferably 0.05 to 0.15 g/cm3. The three-dimensional netted structure1preferably has, for example, a width of 0.1 m to 2 m and a thickness of 5 mm to 200 mm, and extends endlessly in the lengthwise direction. The netted structure is cut to a suitable length (for example, 90 mm) but the sizes of the netted structure are not limited to the examples mentioned above.

A three-dimensional netted structure2(refer toFIG. 2B) of the second mode of embodiment is four-surface-molded, and all the surfaces of the netted structure extend straight. This netted structure is formed so that the density of the regions thereof which correspond to those of the three-dimensional netted structure1of the first mode of embodiment, and which extend inward from the left and right surfaces of the netted structure toward an inner portion thereof by a predetermined distance, becomes high, and so that the density of the region of the netted structure which is at a central inner portion thereof be set lower than the mentioned density. Namely, the regions of the netted structure which extends from all the surfaces thereof except the upper and bottom surfaces thereof to an inner portion of the netted structure by a predetermined distance are molded to a density higher than the above-mentioned density.

A three-dimensional netted structure3of the third mode of embodiment has a surface of modified shapes or a polyhedral surface. This type of netted structures include, for example, a netted structure3A (refer toFIG. 4A) provided with a convex surface, a netted structure3B (refer toFIG. 4B) provided with a concave surface, a netted structure3C (refer toFIG. 4C) provided with a plurality of continuously formed projecting and recessed portions, a netted structure3D (refer toFIG. 4D) provided with a plurality of saw-tooth-like portions, a netted structure3E (refer toFIG. 4E) provided with a plurality of wavy portions, a netted structure3F (refer toFIG. 4F) provided with rounded corner portions, a netted structure3G (refer toFIG. 4G) provided with cut corner portions of a predetermined angle (45°), or a suitable combination thereof, etc. In a job site of the execution of construction work, various modes of netted structures are demanded as products, and this embodiment can meet a demand for such netted structures. It is considered that forming netted structures of complicated shapes causes various uses thereof to be newly found. Especially, forcibly molding three or four surfaces of the three-dimensional netted structure as in the above-described first and second modes of embodiment enables the various demands for the products to be met. Furthermore, in order to obtain netted structures having demanded miscellaneous surface shapes, netted structures are generally cut or molded so as to provide surfaces of modified shapes thereon on a later stage. According to this mode of embodiment, products can be provided instantly without finishing the netted structure as to the shape and sizes, which the products demand, on a later stage, so that a later stage can be rendered unnecessary.

The three-dimensional netted structure4(refer toFIG. 2C) of the fourth mode of embodiment is provided with a single or a plurality (two in this embodiment) of hollow portions4A,4B, and aims at further reducing the manufacturing cost.

The three-dimensional netted structure5(refer toFIG. 2D) of the fifth mode of embodiment has regenerated members5C,5D of the same or different materials, such as plate type regenerated veneer members, plate type members of regenerated shredder dust and the like inserted in hollow portions5A,5B identical with the hollow portions4A,4B of the three-dimensional netted structure of the fourth mode of embodiment. This embodiment aims at improving the sound absorbability, heat insulating characteristics, cushioning characteristics and the like of the netted structure by using regenerated plate members.

In the three-dimensional netted structure6(refer toFIG. 2E) of the sixth mode of embodiment, the sound absorbing characteristics, heat insulating characteristics, cushioning characteristics and impact resistance thereof are improved by increasing the density of parts of the inner portion of the same three-dimensional netted structure1as in the first mode of embodiment in the direction of the thickness thereof, and thereby partly forming a single or a plurality (three in the sixth embodiment) of beam-like high-density regions6A,6B and6C at predetermined intervals.

In the three-dimensional netted structure7(refer toFIG. 2F) of the seventh mode of embodiment, the sound absorbing characteristics, heat insulating characteristics, cushioning characteristics and impact resistance thereof are improved by increasing the density of parts of the inner portion thereof in the widthwise direction thereof, and thereby partly forming a plurality (one in this embodiment) of or a single high-density region7A.

In the three-dimensional netted structure8(refer toFIG. 2G) of the eighth mode of embodiment, the sound absorbing characteristics, heat insulating characteristics, cushioning characteristics and impact resistance thereof are improved by forming a wavy high-density region8A in an inner portion of the same three-dimensional netted structure as in the seventh mode of embodiment.

In the three-dimensional netted structure9(refer toFIG. 3A) of the ninth mode of embodiment, the sound absorbing characteristics, heat insulating characteristics, cushioning characteristics and impact resistance thereof are improved by forming a sheet9A (non-void-carrying region) in a predetermined widthwise extending inner portion of the same three-dimensional netted structure as those1,2. Around the sheet9A, filaments (resin threads) are entangled with one another. The sheet9A may be provided fully in the lateral direction as shown in the drawing, and also partly, for example, in the central portion and the like.

The sheet9A in the three-dimensional netted structure9(refer toFIG. 3B) of the ninth mode of embodiment is wave form in general and the sound absorbing characteristics, heat insulating characteristics, cushioning characteristics and impact resistance of the netted structure are improved. The reason why the sheet9A can be molded in wave form resides in that a draw-down speed of rolls is lower than a resin thread dropping speed as will be described later. The intervals, height and width of the waves of the sheet9A differ depending upon the manufacturing conditions, and are not limited to those shown in the drawing. When the intervals of the waves of the sheet9A are small, the waves are bonded to one another in some cases. The ninth mode of embodiment can be manufactured by using a slit (linear through hole)75ashown inFIG. 11E.

Although illustrations are omitted, the present invention can also be applied to three-dimensional netted structures of modified cross-section shapes, such as a triangular cross-section shape, a Y-type cross-section shape and the like.

(Apparatus for Manufacturing a Three-Dimensional Netted Structure)

An apparatus10for manufacturing a three-dimensional netted structure will now be described.

This apparatus10for manufacturing a three-dimensional netted structure includes as shown inFIG. 5. an extrusion molding machine11, a pair of endless conveyors14,15(refer toFIG. 7) provided with endless members12,13, a motor16adapted to drive the endless members12,13, a transmission17formed of a chain and a gear and adapted to change a moving speed of the endless members12,13, a water tank18adapted to partly submerge the two endless conveyors14,15therein, a control unit19, and other meters, etc.

The endless members12,13are formed by fixing with screws (not shown) a plurality of metal (stainless steel and the like in this embodiment) plate members21to a plurality (two for each conveyor) of endless chains12a,13a(refer toFIGS. 7A and 7B) with a predetermined width of clearance22(refer toFIG. 8A) left therebetween. Instead of these plate members, a belt23of a stainless steel mesh (metal net) which does not have the clearance22may also be used as shown inFIG. 8B. This mesh belt is formed by combining spiral wires with rods (power ribs), and various types of mesh belts are formed by varying the shapes, diameters and pitch of these two elements. Such mesh belts move smoothly, keep the smooth belt surfaces horizontal excellently, stand use in hot temperature condition excellently, and are repaired simply. As shown by dotted lines inFIG. 7, stainless mesh belts23passed around outer circumferences of the endless members12,13can also be used in practice, and are preferably used when it is desirable to prevent the occurrence, which is ascribed to the presence of the clearance22, of recessed and projecting portions on the mesh belt. The cross section of the plate member21is rectangular, and various modified modes of plate members21are conceivable which include a convex plate member24(refer toFIG. 8C), a concave plate member25(refer toFIG. 8D), a saw-tooth plate member26(refer toFIG. 8E), a continuously recessed and projecting plate member27(refer toFIG. 8F), etc.

As shown inFIG. 7, the endless conveyor14is provided with a driving shaft14bhaving a sprocket14aaround which the endless chain12aprovided vertically is passed, and a driven shaft14dhaving a sprocket14c. The endless conveyor15is driven synchronously with the endless conveyor14, and provided with a driven shaft15bmounted with a sprocket15aaround which the endless chain13ais passed, and a driven shaft15dmounted with a sprocket15c.

As shown inFIG. 5, the extrusion molding machine11includes a container31, a raw material feed port32provided on an upper portion of the container31, a die33, a mouthpiece34capable of being fixed detachably to a lower end portion of the die33. A range of the temperature in an inner portion of the die of the extrusion molding machine11can be set to 100 to 400° C., and an extrusion rate of the machine20to 200 Kg/hr and the like. A range of the pressure in the die is 0.2 to 25 MPa, which is equal to, for example, a discharge pressure of a 75 mm screw. When the thickness of the three-dimensional netted structure exceeds 100 mm, the equalization of the pressure in the die by a gear pump and the like is needed in some cases. Therefore, it becomes necessary that the pressure in the die be increased by a gear pump and the like so as to discharge filaments uniformly from the whole region of the interior of the die. To meet the requirement, the surfaces of the endless conveyors14,15are formed so that these surfaces can be moved freely so as to set the shape of a three-dimensional netted sheet. This enables a product having desired density and strength to be manufactured in accordance with the shape (density or diameter of the holes H) of the mouthpiece34of the die33and a transfer speed of the endless conveyors14,15, and various demands for the products to be met.

An apparatus50for manufacturing a three-dimensional netted structure which is made of such a four-surface-molding machine as shown inFIGS. 9A and 9Bwill now be described. This apparatus50for manufacturing a three-dimensional netted structure is provided with endless conveyors54,55having rotary shafts54a,55awhich correspond to the endless conveyors14,15used in a two-surface-molding operation shown inFIG. 7, and a pair of rolls56,57disposed at lengthwise end portions of the endless conveyors54,55and having rotary shafts56a,57aextending at right angles to the shafts of the endless conveyors. The rotary shaft54ais mounted with bevel gears54b,54c, while the rotary shafts56a,57aare also mounted with bevel gears56b,57b. The bevel gears54b,54cand the bevel gears56b,57bare meshed with each other, and the rotary shafts54a,55aare driven synchronously by a motor M via a chain C. Therefore, the rotary shafts56a,57aare also driven synchronously. The other end portions of the rotary shafts56a,57aare supported on bearings58a,58b.

As shown inFIG. 9C, the apparatus may be an apparatus formed by arranging a pair of short endless conveyors59a,59b, the construction of which is identical with the endless conveyors54,55, at right angles to rotary shafts of rolls. In this case, the molding of a product can be done more precisely, and the dimensional accuracy of a product is improved.

As shown inFIG. 9D, the manufacturing of a three-dimensional netted structure can be done by using four-surface-molding techniques. The three-surface-molding of the product can also be done by using the mentioned techniques as shown inFIG. 9E. Namely, when a certain type of three-dimensional netted structure is manufactured, two systems of dies are provided, and filaments are extruded in parallel. As a result, the productive efficiency of the netted structure doubles.

As shown inFIG. 10A, an apparatus of a modified mode can be also used which is formed by providing driving power sources (motors) instead of the previously-mentioned synchronous driving system so that endless conveyors64,65and rolls66,67(endless conveyors also serve the purpose) are driven independently of each other. Namely, in order to carry out three-surface or four-surface-molding operation, endless conveyors64,65having rotary shafts64a,65a, and a pair of rolls66,67arranged at lengthwise end portions of these endless conveyors64,65, and having rotary shafts66a,67aextending at right angles to those of the endless conveyors are provided. The rotary shafts66a,67aare also provided with respective motors M so that these rotary shafts are driven independently of each other. The other end portions of the rotary shafts66a,67aare supported on bearings68a,68b.

As shown inFIG. 10B, which shows another modified mode of the apparatus, in which a driving mechanism can be simplified by removing such two rolls66,67, two rotary shafts66a,67a, two bearings68a,68band two motors M as are provided in the preceding example, and providing sliding curved plates69a,69b, the surfaces of which are coated with polytetrafluoroethylene, in positions in which the rolls66,67were placed. These curved plates69a,69bare arcuate in side elevation and positioned so that a distance between these curved plates decreases gradually from upper portions thereof toward lower portions thereof. The curved plates are formed to a rectangular shape in plan.

The holes of the mouthpiece34are downwardly made in series, from which filaments come out downward. The holes may be arranged at regular intervals or at non-regular intervals. The holes may employ staggered, orthogonal and various other types of configurations. When it is desired that the arrangement density of the holes be changed, a method of positively increasing the arrangement density thereof in end regions only is used in some cases. Changing the mode of the mouthpiece variously enables various demands for the products to be met. Mouthpieces of a multiplicity of specifications can be used practically which include, for example, a mouthpiece71(having holes H accounting for 90% of the area of the mouthpiece71)(refer toFIG. 11A) of 1.0 m×180 mm in which about 3500 holes H of 0.5 mm in diameter are made, a mouthpiece72(refer toFIG. 11B) in which the density of the holes H is set high only in a circumferential portion72athereof, a mouthpiece73(refer toFIG. 11C) in which the density of the holes H of frame-forming portion73bis increased so that the frame-forming portion constitutes series-connected frames, a mouthpiece74(refer toFIG. 11D) in which slits (linear through holes)74ato74cin addition to a multiplicity of holes H are formed so that the slits extend in parallel with shorter sides of the mouthpiece, a mouthpiece75(refer toFIG. 11E) in which a slit (linear through hole)75ain addition to a multiplicity of holes H is formed so that the slit extends in the lengthwise direction of the mouthpiece, a mouthpiece76(refer toFIG. 11F) and the like in which a slit (linear through hole)76ain addition to a multiplicity of holes H is formed so that the slit extends in a position near a lengthwise side of the mouthpiece, and similar other mouthpieces, and a mouthpiece77(refer toFIGS. 11G and 11H) and the like which have regions77c,77dnot provided with the holes H so as to make hollow portions therein, and which is provided under these regions with cross-section square introduction members (pipes, etc.)77a,77bprojecting downward therefrom. The density of the holes H formed in these mouthpieces is preferably 1 to 5/cm2.

(Method of Manufacturing a Three-Dimensional Netted Structure)

This three-dimensional netted structure1is manufactured in the following manner. First, flakes of regenerative PET bottles are heated and dried for preventing the same from being hydrolyzed, and chemicals for excellently finishing the resultant product, or an antibacterial agent and the like are added suitably to the same product in some cases. When filaments come out flat from the mouthpiece34in the downward direction, the filaments are entangled helically owing to the entangling actions of the endless members12,13of the endless conveyors14,15. The filaments start being entangled at the portions thereof which contact the surfaces of the endless members12,13at the entangling-starting time. The density of the portions of the filaments which are entangled is high, and that of the portions thereof which are not entangled is low.

Next, as shown inFIG. 6, a three-dimensional netted structure1, an object netted structure is manufactured by extruding a molten thermoplastic resin downward from a plurality of dies33, having the extruded filaments of the resin drop naturally to a position between a pair of partly submerged endless conveyors14,15, and drawing down the filaments of the resin at a speed lower than the filament dropping speed. When this netted structure1is thus manufactured, the two endless conveyors14,15are arranged so that a distance between the endless conveyors is set smaller than a width of an assembly of the extruded filaments of the molten resin, and so that both or one surface of the assembly of the filaments of the molten resin contacts the endless conveyors14,15before or after these conveyors are submerged.

Both or one of the surface portion of the assembly of the molten thermoplastic resin drops on the endless conveyors14,15, and moves to an inner side of the assembly, so that the surface portion of the assembly becomes dense. Therefore, the percentage of void of the surface portion becomes lower than that of a central portion which drops as it is into the water. It is a matter of course that the surface portion in which the percentage of void becomes low comes to have an increased number of nodes as compared with the central portion having a high percentage of voids, and that the tensile strength of the surface portion becomes noticeably high. The surface portion having a low percentage of void comes to have a small area of voids, and forms an impact absorbing layer and a soundproofing layer.

A result showing that a percentage of void of the three-dimensional netted structure1as a whole high enough to have the netted structure function well is in the range of 50% to 98%, though these levels differ with the condition of execution of works on a job site was obtained. In short, it is considered that, when the density of the netted structure is high, sounds are blocked. A result showing that, in order to have the three-dimensional netted structure function as a recycled sound absorbing building material, a cushioning material, a heat insulating material and the like, the percentage of void thereof may be set preferably to not lower than 70% was obtained. In short, when the percentage of void is lower than 70%, the impact absorbing effect, soundproofing effect, heat insulating effect and cushioning characteristics of the netted structure are not in some cases so improved as was expected. It is recommended that the three-dimensional netted structure1may be designed suitably with the percentage of void set in the range of 70% to 98% in accordance with the use of the netted structure.

A sound absorbing material and a cushioning material have a preferable percentage of void of 85 to 98%, an impact absorbing material to be provided under a floor 40 to 80%, and a collision-preventing impact absorbing material 60 to 90%. A preferable range of the percentage of void varies with the use of the netted structure.

The percentage of void=100−{(B÷A)×100}, wherein A represents a product of the specific gravity of the resin and the volume of the three-dimensional netted structure; and B represents the weight of the netted structure.

The thermoplastic resin used in this method is obtained by pulverizing PET bottles into flakes, which are used as a raw material or a main raw material. However, resins including a polymer, such as polypropylene, etc. or a resin obtained by blending a plurality of kinds of polymers together, etc. may be used as a main raw material without trouble as long as the resin can be processed by a regular extrusion molding machine.

In the step of forming three-dimensional netted structures to final modified shapes, a mechanism for equalizing the inner pressure of the dies, and drawing down an assembly of filaments at two, three or four surfaces thereof or at an intermediate portion thereof is used. This enables such characteristics to be given to this netted structure manufacturing method that include its capability of attaining an apparent density of a product of 0.02 to 0.9 g/cm3, changing the filaments of the molten resin from a randomly and helically entangled state into a state of a flat plate, and turning the surface portions of the three-dimensional netted structure including the front, rear, left end and right end surfaces with respect to the direction of the thickness thereof into flat surfaces and surfaces of modified shapes, i.e. projecting and recessed surfaces. The mouthpiece of a die used to form the three-dimensional netted structure is made so that a netted structure of a rod type shape, modified shapes (shape of a pipe and a shape of the letter “Y”), etc. and a netted structure of various other shapes devised by combining these shapes together can be obtained. The three-dimensional netted structure is subjected to compression by the rolls of a draw-down machine to obtain a super-dense sheet structure. The inner pressure of the dies used to have the regenerated PET resin discharged uniformly from the dies is equalized, and the three or four surfaces of an assembly of filaments of a molten resin extruded when the three-dimensional netted structure is manufactured is brought into contact with the draw-down conveyors by which these surfaces are shaped. In short, the assembly of filaments of the molten regenerated PET resin is formed at the three or four surfaces thereof to shapes of a final product. For example, a resin filament assembly is drawn up as necessary around polygonal conveyors to form a product. In one of the methods of obtaining a three-dimensional netted sheet, filaments of a molten resin are extruded downward from a plurality of dies, and dropped naturally onto water surface or to a position between partly-submerged conveyors. Thus, a randomly and helically entangled filament assembly is made, which forms a three-dimensional netted sheet.

It was ascertained that, when the speed of the endless conveyors was varied, the density of a sheet of 1.0 m in width and 100 mm in thickness varied.

It was further ascertained that the density of the sheet varied in accordance with the variation of a discharge rate of the extruder.

The mouthpiece34having about 3500 substantially regularly spaced holes H of 0.5 mm in diameter was fixed to the dies33having an area of 1.0 m×180 mm in a uniaxial extruder having a screw of 75 mm in diameter. The water tank18having a water level in a position about 120 mm below the dies33is provided, and a pair of endless conveyors14,15of 1.2 m in width were installed substantially vertically in the tank with a clearance of 50 mm left therebetween, in such a manner that upper portions of the endless conveyors project upward from the water level by around 40 mm.

In this apparatus, the molten resin filament assembly was extruded from the mouthpiece34at an extrusion rate of 120 kg/hr to a position between the endless conveyors14,15so that two surfaces of the molten resin filament assembly dropped on the endless conveyors, by controlling the temperature of the dies33so that the temperature of the resin became 240° while plasticizing a regenerated PET resin by heating the same. During this time, the draw-down speed of the endless conveyors14,15was set to 0.7 m/min. The molded product held between the endless conveyors14,15and moved down changed its direction in a lower portion of the interior of the water tank18, and was moved from the side of the water tank which is opposite to the extruder to the water surface. When the molded product came out of the water tank18, the water thereon was blown off with compressed air or by a vacuum pump.

The three-dimensional netted structure thus obtained had a width of 1.0 m, a thickness of 50 mm, and a density of 0.07 g/cm3to 0.14 g/cm3. This netted structure may be used as a heat insulating material, a ground material, and a sound absorbing material, and for a drain pipe, etc.

The above-described three-dimensional netted structure1and apparatus10for manufacturing the same netted structure enable a finishing operation on a later stage to be omitted, the degree of straightness of surfaces of the netted structure to be improved, a demand for a netted structure having modified shapes to be met, and the durability of the netted structure to be improved.

Owing to this mode of embodiment, the PET bottles which do not have uses in the existing circumstances newly find a use as materials for a three-dimensional netted structure, and it is considered that a recovery percentage of the PET bottles will increase. This causes the recycling of the PET bottles to be greatly promoted.

FIG. 12shows a modified mode of the apparatus50for manufacturing a four-surface-molded three-dimensional netted structure, andFIG. 12Ais a drawing corresponding toFIG. 9Band shows a pair of rolls56,57as described above which have a single or a plurality of projections90ato90con the respective surfaces thereof (the illustrations of the roll57and its projections are omitted). These projections are formed so as to provide recesses in side surfaces of the three-dimensional netted structure. Each of the projections90ato90chas angular portions and an arcuate side portion in cross section. Although the recesses referred to above and formed in the side surfaces of the netted structure ought to become rectangular theoretically, the recesses become curvilinear since the resin filaments drop into the space between the endless conveyors from above as above-mentioned, to cause blind regions in which the resin filaments do not enter to occur. In short, the recesses become roundish.FIG. 12Bcorresponds toFIG. 9C, and shows endless conveyors (the illustrations of the endless conveyor55and its projections are omitted) formed by providing a single or a plurality of projections96on the surfaces of two endless belt conveyors like those of the above-mentioned belt conveyors54,55, etc. This modified apparatus can also be formed by incorporating cams and springs in the rotary bodies, such as the above-mentioned rolls56,57or endless conveyors54,55so that the projections are forced out in the outward direction by the cams synchronously with the rotations of the rotary bodies. This enables the occurrence of blind regions to be reduced, and more precise recesses to be formed. Since the construction of the other parts is identical with that of the corresponding parts of the apparatus shown inFIGS. 9B and 9C, the illustrations and description of the latter will be utilized and quoted.

A second mode of embodiment will now be described. The demands for the recycling of the products of the three-dimensional netted structures have become diversified, and cannot be met under the present circumstances in some cases. For example, when it is desired that a mixture of not smaller than two kinds of regenerated resins be utilized, some of these raw materials prove separable during recycling operations therefor, and some non-separable. In a scene of labor for recycling raw materials, non-separable raw materials are sometimes mixed in a starting material, and the recycling and utilizing of raw materials actually become impossible in some cases in spite of the effort made to recycle the materials. There are various cases where the same raw material is used for a certain purpose, which include a case where changing the shape of a product is desired, such as a case where forming sparse and dense regions is desired, a case where forming hollow portions on a later stage is desired and similar cases, or a case where improving the moldability of the materials is desired.

Therefore, this mode of embodiment is carried out so as to prevent troubles from occurring in the regeneration of a thermoplastic resin, and attain the easiness of changing the shape of a product.

A three-dimensional netted structure101of a tenth mode of embodiment is a plate type three-dimensional netted structure, the characteristics of which reside in that the netted structure is formed by using a regenerated thermoplastic resin as a raw material or a main raw material, and has a plurality of filaments helically and randomly entangled and partly and thermally bonded together as shown inFIG. 13A. This netted structure is made of an inner region101aand an outer region101bof the same or different raw materials. A boundary between the inner region101aand outer region101bis shown by a solid line. The solid line is an imaginary line showing the boundary, and the same applies to the other modes of embodiment which will be described later. It is preferable that the densities of two, three or four surface portions of this three-dimensional netted structure may be relatively higher than that of the portion of the netted structure which is exclusive of these surface portions. Namely, the three-dimensional netted structure101(refer toFIG. 13A) of the tenth mode of embodiment is two-surface-molded. This netted structure is molded so that the density of regions thereof which extend from the opposite surfaces thereof toward an inner portion thereof by a predetermined distance is high. The density of an inner part of the central portion thereof is set lower than the mentioned density, and the other non-surface-molded surfaces are not straight-formed. Therefore, it becomes unnecessary that this netted structure may be processed on a later stage. In short, a pair of surfaces of a large width and one side surface of the netted structure are forcibly molded by endless conveyors which will be described later, and edges of these surfaces are set more beautifully than those of the other surfaces.

A three-dimensional netted structure102(refer toFIG. 13B) of an eleventh mode of embodiment is a three-surface-molded netted structure, in which all the surfaces except the end surfaces and one side surface are set straight. The regions extending from all the surfaces of the netted structure except the right side surface thereof toward an inner portion thereof by a predetermined distance are molded to a high density. This netted structure is made of an inner region102aand an outer region102bof the same or different raw materials.

A three-dimensional netted structure103(refer toFIG. 13C) of a twelfth mode of embodiment is four-surface-molded, in which all the surfaces thereof except an end surface thereof are set straight. This netted structure is formed by molding the regions, which extend from the left and right side surfaces of the same netted structure as that of the first mode of embodiment to the inner part of the central portion thereof by a predetermined distance, to a high density with the density of the region in the inner part of the central portion of the netted structure set lower than the mentioned density. Namely, the regions extending from all the side surfaces of the netted structure toward the inner portion thereof by a predetermined distance are molded to a high density. This netted structure is made of an inner region103aand an outer region103bof the same or different raw materials.

A three-dimensional netted structure104(refer toFIG. 13D) of a thirteenth mode of embodiment is a three-dimensional netted structure provided with a single or a plurality of (one in this embodiment) hollow portions104c, and formed for the purpose of further reducing the cost and for some other purposes. This netted structure is made of an inner region104aand an outer region104bof the same or different raw materials.

A three-dimensional netted structure105(refer toFIG. 14A) of a fourteenth mode of embodiment is formed of three layers of regions105a,105band105cof the same or different raw materials. The raw materials of all of the three layers of regions may be different. The raw materials of the regions105a,105cmay be identical, and that of the region105bmay be different. The raw materials of the three layers of regions may be all identical. The netted structure is divided into three layers of regions105a,105band105cin the lengthwise direction thereof.

A three-dimensional netted structure106(refer toFIG. 14B) of a fifteenth mode of embodiment is made of two layers of regions106a,106bof the same or different raw materials. The raw material of the two layers of regions106a,106bmay be different or identical. This netted structure is divided into two layers of regions106a,106bin the lateral direction thereof.

A three-dimensional netted structure107(refer toFIG. 14C) of a sixteenth mode of embodiment is made of two layers of regions107a,107bof the same or different raw materials. The raw materials of the two layers of regions107a,107bmay be different or identical. The direction in which this netted structure is divided into these regions is that of the thickness of the netted structure unlike the direction in which the fourteenth and fifteenth modes of embodiment are divided.

In the embodiment shown inFIG. 3, a high-density sheet9A (a substantially non-void-carrying filled region) can be provided partly in a predetermined position in the lateral direction in the embodiment by forming the sheet and the other region by different extrusion molding machines through different paths. The description of this embodiment will be quoted from that given previously with respect to the embodiment ofFIG. 3.

Beside these netted structures, netted structures of modified cross-section shapes, such as a triangular shape, a shape of the letter “Y”, etc., the illustrations of which are omitted, can also be formed in practice. As mentioned above, when a raw material is supplied to not smaller than two regions provided on the mouthpiece, the regulation of the manufacturing conditions, such as the temperature of the raw material, extrusion rate of the filaments, etc. can be made easily.

An apparatus110for manufacturing a three-dimensional netted structure of a second mode of embodiment will now be described.

This apparatus110for manufacturing a three-dimensional netted structure include as shown inFIG. 15an extrusion molding machine111, a pair of endless conveyors114,115provided with endless members112,113, a motor116for driving the endless members112,113, a transmission117formed of chains and gears and adapted to change the moving speed of the endless members112,113, a water tank118for submerging parts of the endless conveyors114,115therein, a control unit119and meters, etc.

The description of endless members112,113, etc. will be described by quoting that given previously with respect to the first mode of embodiment.

As shown inFIG. 15, the extrusion molding machine111is formed of containers131a,131bstoring therein the same or different raw thermoplastic resin materials, raw material supply ports132a,132bprovided at upper portions respectively of the containers131a,131b, raw material supply pipes133a,133bconnected to the containers131a,131brespectively, a complex die135(refer toFIG. 16) connected to the raw material supply pipes133a,133bvia packings134a,134b, a mouthpiece136(refer toFIG. 16) detachably fixable to a lower end portion of the complex die135, etc. The raw material supply pipe133abranches at an intermediate portion thereof into a plurality of (four in this embodiment) pipe members striding over the raw material supply pipe133b. The lower end portions of the branches of the raw material supply pipe133aare arranged around that of the raw material supply pipe133b. As shown inFIGS. 16A and 16B, the complex die135has a frame type partition wall139in an inner region of an outer frame138so that the interior of the complex die135is divided into two chambers137a,137b, i.e., the complex die is formed so that the same kind of raw material or two different kinds of raw materials supplied thereto via the raw material supply pipes133a,133bare not mixed with each other. Even when the raw material supplied through these supply pipes is the same, it is preferable to provide the partition wall139for the purpose of regulating the extrusion rates separately. The particular parts of the interior of the die of the extrusion molding machine111are formed by utilizing the corresponding parts of the first mode of embodiment. Although the raw material supply pipe133ais made to branch into four members, the pipe may also be made to branch into a suitable number of members, such as two members (refer toFIG. 17A), three members (refer toFIG. 17B), etc.

A mouthpiece136has not smaller than two regions so that a raw material is supplied thereto separately. Therefore, the regulation of the extrusion speed or extrusion rate of filaments is made very easily, and the moldability of the raw material is improved remarkably. The details of a description of the mouthpiece will be given by quoting the corresponding parts of the description of the first mode of embodiment. In this embodiment, a mouthpiece171(the area of the region thereof which is provided with holes H accounts for 90% of a total area of the mouthpiece171)(refer toFIG. 18A) having the holes at substantially regular intervals or at suitable intervals is used. In this mouthpiece171, an inner region171aand an outer region171bare defined by a partition wall171cshown by a broken line, and filaments of the same or different materials are extruded separately and independently from these regions correspondingly to raw material supply pipes133a,133b.

A mouthpiece172(refer toFIG. 18B) may also be used, in which an inner region172aand an outer region172bwhich are provided with a multiplicity of holes H are defined by a partition wall172cshown by a broken line. The inner region172ais formed in a deflected manner with respect to the outer region172bso that the filaments corresponding to the inner region172aare separated easily.

A mouthpiece173(refer toFIGS. 18C and 18D) may also be used. An inner region173aand an outer region173bwhich are provided with a multiplicity of holes H are defined by a partition wall173cshown by a broken line. The inner region173ais held between the pair of outer region173b. In order to form hollow portions in this mouthpiece, regions173d,173ewhich do not have holes H are provided in the portions thereof which correspond to the hollow portions, and cross-section square introduction members (pipes and the like)173f,173gextending downward are provided on lower portions of the two regions.

A mouthpiece174(refer toFIG. 19A) may be also used, in which an upper region174a, a central region174band a lower region174cwhich are provided with a multiplicity of holes H are defined by partition walls174d,174eshown by broken lines to form three stages (three layers) of regions.

A mouthpiece175(refer toFIG. 19B) may be also used, in which an upper region175aand a lower region175bwhich are provided with a multiplicity of holes H are defined by a partition wall175cshown by a broken line to form two stages (two layers) of regions.

A mouthpiece176(refer toFIG. 19C) may be also used, in which a left region176aand a right region176bwhich are provided with a multiplicity of holes H are defined by a partition wall176cshown by a broken line to form two rows (two layers) of regions.

A mouthpiece177(refer toFIG. 19D) may be also used, in which a region177aprovided with a multiplicity of holes H, and a slit (linear hole)177bformed in a suitable portion, such as a central portion, etc. so as to extend parallel to a predetermined direction (lengthwise direction in this example) are defined by partition walls177cshown by broken lines. The slit177bexists in a region between the partition walls177cshown by broken lines. The width, length or position of the slit (linear hole)177bcan be suitably selected. When a raw material is supplied from the same die to the region177ahaving many holes H and slit (linear hole)177b, the wavy form ofFIG. 3Bis deformed, and the moldability of the material is deteriorated in some cases. However, when the above-mentioned mouthpiece177is used, the raw material is supplied from not smaller than two kinds of extrusion molding machines111separately and independently to the holes H of the region177aand slit177b, so that a suitable wavy form is obtained. Instead of the slit177b, holes H may be provided. In such a case, it is recommended that the density of the holes H be set high.

Besides these mouthpieces, mouthpieces of various other specifications can be used in practice. The density of the holes H formed in the above-described mouthpieces is preferably set to 1 to 5/cm2.

The method of manufacturing a three-dimensional netted structure of the first mode of embodiment, etc. is utilized.

According to the three-dimensional netted structures101to107of the tenth to sixteenth modes of embodiment, a resin difficult to be separated or a resin impossible to be separated is used to form the first region101a, while a resin possible to be separated is used to form the second region101b, this resin being separated during a recycling operation, so that the recycling operation can be carried out repeatedly.

A three-dimensional netted structure divided into regions in accordance with the properties of the thermoplastic resins can be manufactured, and the recycling of the thermoplastic resins can be done smoothly. A simple operation, such as a region separating operation or some other similar operation advantageously makes it possible to change the shape of the netted structure afterward. Since a raw material is supplied to the mouthpiece from a plurality of extruders separately and independently, the moldability of the material for the three-dimensional structure is improved.

An apparatus210for manufacturing three-dimensional netted structure of a third mode of embodiment aims at providing a method of and an apparatus for manufacturing a three-dimensional netted structure, capable of preventing the deformation, which causes inconveniences, of the endless belts, omitting a finishing operation on a later stage, improving the degree of straightness of the surfaces of a netted structure, meeting a demand for a netted structure of modified shapes, and manufacturing a netted structure of an improved durability.

The construction of the parts of the apparatus for manufacturing the three-dimensional netted structure210which are different from the corresponding parts of the apparatuses of other modes of embodiment will be described by utilizing the description of the first mode of embodiment, etc. The apparatus210is formed of an extrusion molding machine211, a pair of rolls212,213provided in horizontal positions spaced from each other by a predetermined distance, a pair of rolls214,215(refer toFIG. 20andFIG. 21) provided below and in alignment with the two rolls212,213horizontally so as to be spaced from each other by a predetermined distance, a motor for driving the rolls212to215, a transmission formed of chains and gears and adapted to change the moving speed of the rolls212to215, a water tank for partly submerging of the two rolls212,213and completely submerging the two rolls214,215, a control unit, meters, etc. Referring toFIG. 20, a structure provided with three rolls by removing one of the lower rolls may be employed.

The rolls212,213may be formed of cross-section circular rolls224(refer toFIG. 22A) as well as rolls of modified shapes. Various modified modes of rolls are conceivable which include, for example, a roll225(refer toFIG. 22B) having a cross-section saw-tooth outer circumference, a roll having continuously formed recesses and projections, for example, a roll226(refer toFIG. 22C) having an outer circumferential surface similar to that of a gear in section, a roll227(refer toFIG. 22D) having not smaller than one projection227a(for example, a triangular or circular projection) on an outer circumferential surface thereof, a cross-section elliptic roll228(refer toFIG. 22E), a cross-section triangular or a hand-made or mechanically molded rice-shaped roll229(refer toFIG. 22F), a cross-section polygonal roll, for example, a cross-section octagonal roll230(refer toFIG. 22G), etc.

As shown inFIG. 21, the rolls212to215are provided with driving shafts212ato215arespectively. The driving shafts212ato215aare supported rotatably on the respective bearings, and driven in the directions of arrows inFIG. 20by a driving motor via the transmission.

According to the apparatus210described above for manufacturing a three-dimensional netted structure, it becomes possible to omit a finishing operation carried out in a later stage, heighten the degree of straightness of surfaces of a netted structure, meet a demand for obtaining netted structures of modified shapes and improve the durability of a netted structure.

A three-dimensional netted structure401of a seventeenth mode of embodiment is a netted structure in which sparse portions and dense portions are provided. This netted structure can be applied to, for example, a wall material from which a gardening container is suspended, a deck on which a gardening container is placed, a blind, a screen, a bamboo blind-like article, a fence, and a gardening cushioning material applied to a floral decoration and the like.

The sparse and dense portions of the three-dimensional netted structure401are formed through an operation for regulating a transfer speed of the draw-down unit, for example, endless conveyors or rollers, by controlling the rotational speed of the motor. This method enables a netted structure having sparse and dense portions stabler than those of a netted structure manufactured by regulating the liquid pressure of the extrusion molding machine to be obtained.

As shown inFIG. 23A, low-density portions401aand high-density portions401bare formed in order and in repetition. In addition, as shown inFIG. 23B, hollow portions406A,406B are provided through a netted structure so as to extend in a predetermined direction. A modified mode of this netted structure may be a gardening cushioning material402having a plurality of small through holes407ato407dextending therethrough in the lengthwise direction as shown inFIG. 23D. The ranges of the density of the sparse portions401aand dense portions401bcan be set suitably. The raw material of the thermoplastic resin, etc. will be described by utilizing the description of those of the first mode of embodiment.

In order to make hollow portions in the netted structure, regions477a,477bnot provided with the holes H are formed in the corresponding parts of the mouthpiece471as shown inFIG. 24, and downwardly extending cross-section square introduction members (plate members, pipes, etc.)477c,477dare provided (refer toFIG. 24B) on lower portions of these regions. There is another example of the mouthpiece which is formed of a mouthpiece481(the area of the region thereof which is provided with the holes H accounts for 90% of a total area of the mouthpiece)(refer toFIG. 24C) in which a predetermined number of holes H are formed at substantially regular intervals. In order to form hollow portions in the netted structure, this mouthpiece is provided with regions487ato487dnot provided with the holes H in the corresponding parts thereof, and downwardly extending cross-section square introduction members (plate members, pipes, etc.)488ato488dare provided (refer toFIG. 24D) on lower portions of the mentioned regions. The density of the holes H formed in the mouthpiece is preferably 1 to 5/cm2. Besides these mouthpieces, mouthpieces of various specifications can be used in practice.

The three-dimensional netted structure401can be used as substitutes for a wall member from which a gardening container is suspended, a wall member for a floral decoration, a blind and a fence. For example, as shown inFIG. 25, piles480(posts may be used instead) are driven into the ground and set up, and the resultant piles are thrust into the hollow portions406A,406B of the three-dimensional netted structure401and fixed. The three-dimensional netted structure401may be divided into a plurality of parts, and dimensional selectivity thereof may be secured by combining the divided netted structures with each other. A suitable number of hanging baskets482provided with hooks481are hung on the sparse portions401a. The hooks481are hung on sparse portions401amore easily than on dense portions401b. This netted structure can also be utilized as a deck. For example, a three-dimensional netted structure490is not provided with hollow portions but it is manufactured in a step similar to the step of manufacturing the three-dimensional netted structure401, so that a culture pot491, a container492and the like can be placed thereon. The netted structure490can also be applied to a screen, a bamboo blind-like article, a fence, a floral decoration, etc. As shown inFIG. 26, a three-dimensional netted structure402can be utilized as a roof, a screen, and a partition for plants in a median strip of a road. The netted structure402is formed so that it can be fixed to a structure by a suitable device or by passing connecting members403, such as strings, rings, pipes and the like through small holes407ato407cthereof. When this netted structure is utilized as a partition for the plants in a median strip of a road, a glare-proofing effect is displayed with respect to the light of an automobile.

According to the three-dimensional netted structure401described above, it can be applied to a wall member for hanging baskets, a deck, a blind, etc. Moreover, this netted structure reduces the manufacturing cost, and has a durability with respect to the wind and rain and sunlight. The netted structure is not rotted, and the flexure thereof does not occur. The netted structure is rarely discolored. This netted structure can employ various colors, and the coloring of the netted structure can be done freely, so that the range of the selection of colors expands. Moreover, the netted structure has a very high resiliency, and enables a blinding effect to increase and an outer appearance of different sense of quality to be provided, so that the netted structure is very convenient.

The three-dimensional netted structure can also be used as a seedbed for planting a roof with trees. The netted structure is laid in a hole or a recess formed in a suitable position on a gas-permeable and a water-permeable tile. The culture earth is put in the hole or recess, and tree is planted therein.

The three-dimensional netted structure can also be used as a pavement material by pasting gas-permeable and water-permeable tiles on an upper surface thereof. Owing to the netted structure, the temperature can be reduced.

A three-dimensional netted structure can also be manufactured the characteristics of which reside in that the netted structure is formed by preparing as a raw material or a main raw material a thermoplastic resin containing a brittleness causing element, such as an inorganic substance, for example, talc; forming a plurality of helically and randomly entangled and partly and thermally bonded filaments of the raw material by extrusion molding; and cooling these filaments with a liquid, the brittle fracture of the product becoming able to be effected by applying an external force thereto.

A three-dimensional netted structure obtained by preparing a thermoplastic resin as a raw material or a main raw material; forming a plurality of helically and randomly entangled and partly and thermally bonded filaments of the raw material by extrusion molding; cooling these filaments with a liquid, and applying a fire resistant material to the resultant filaments or enclosing the filaments with a nonwoven carbon fiber, or a similar three-dimensional netted structure made of the same thermoplastic resin to which the fire resistant material is added can also be manufactured. The three-dimensional netted structure enclosed with a nonwoven cloth of carbon fiber can be provided in the ceiling and walls.

A three-dimensional netted structure510of the fourth mode of embodiment is manufactured by forming a three-dimensional netted structure501by using curved plates582,583as shown inFIG. 27, instead of using the endless members and rolls. The curved plates582,583extend perpendicularly to the surface of the drawing, and are given at their outer surfaces a slidability by coating the same with polytetrafluoroethylene. The curved plates are rectangular in side elevation. The curved plates582,583are arranged so that a distance therebetween decreases from upper portions thereof toward lower portions thereof. The curved plates582,583may have a fixed structure, or they may be formed so that the density and shape thereof in the lateral and longitudinal directions can be varied by rendering a distance of the curved plates variable as shown by broken lines by reciprocating driving units590,591(for example, fluid pressure cylinders). A curved plate584is also provided below the curved plates582,583, and introduces the netted structure501suitably to a downstream side draw-down unit.

INDUSTRIAL APPLICABILITY

According to the inventions described in claim1tob19, a method of and an apparatus for manufacturing a three-dimensional netted structure, capable of omitting a finishing operation in a later stage, heightening the degree of straightness of side surfaces of the netted structure, meeting a demand for obtaining netted structure of modified shapes, and improving the durability of the netted structure can be provided, and the value of industrial utilization of these inventions in various kinds of industries is very large.