Patent Application
20250230591
The present invention relates to a net structure suitable for cushioning materials for use in office chairs, furniture, sofas, bedding such as beds, seats for vehicles such as trains, automobiles, motorcycles, strollers, child safety seats, and wheelchairs, and mats for absorbing shocks such as floor mats and members for preventing collision or getting caught between something, and a manufacturing method therefor.
Currently, net structures are being widely used as cushioning materials for use in furniture, bedding such as beds, and seats for vehicles such as trains, automobiles and motorcycles. Compared to foam-crosslinked urethane, the net structure has the same level of durability, has excellent moisture permeability and breathability, and has the merit of being less likely to become stuffy because of less heat storage. Furthermore, the net structure is formed of a thermoplastic resin, and has the merits of ease of recycling, free of fear for residual chemicals, and environmental friendliness. In recent years, cushions with different hardnesses depending on the site have been requested for further sophistication in functions of cushioning materials. Also, from the viewpoint of ensuring a zonal region having the same hardness with a minimal width depending on the application, it is required that the boundary between the portions having different hardnesses be clear.
In response to the above request, Patent Literature 1 and Patent Literature 2 disclose varying the hardness of a net structure by varying the apparent density of the net structure.
Also, Patent Literature 3 discloses a method for adjusting the elasticity of a net structure by the frequency of an ultrasonic vibration plate installed in a liquid tank, and by the direction and speed of air blowing by a blower device. Patent Literature 4 discloses a technique for varying hardness by adjusting the manufacturing conditions in a net structure with the same apparent density.
However, when the hardness is varied by the apparent density, as in the net structures disclosed in Patent Literature 1 and Patent Literature 2, the following problems arose. When the apparent density is lowered so as to reduce the hardness of the net structure, the texture of the net structure is impaired. Meanwhile, when the apparent density is increased so as to increase the hardness of the net structure, the mass per unit volume of the net structure increases, and the weight of the entire product increases.
With the method disclosed in Patent Literature 3, it is difficult to manufacture a net structure with clear boundaries between sites with different hardnesses. In the technique disclosed in Patent Literature 4, since the hardness of the entire net structure varies at the same time, it is difficult to partially vary the hardness of the net structure. Also, since the apparent density of the net structure varies, the problem of impairment in texture or increase in weight of the net structure arises.
The present invention has been made in view of such problems of the conventional art, and it is an object of the present invention to provide a net structure that includes portions with substantially the same apparent density while differing in terms of compressive hardness by 5% or more, and has a clear boundary between the portions that differ in terms of compressive hardness.
As a result of repeated research to solve the above problems, the inventors of the present application have finally accomplished the present invention. In other words, the present invention is as follows.
[1] A net structure having a three-dimensional random loop junction structure composed of thermoplastic elastomer continuous filaments, the net structure including portions differing in terms of compressive hardness by 5% or more zonally, a difference in apparent density between the portions differing in terms of compressive hardness being 0.005 g/cm3 or less.
[2] The net structure according to [1], wherein the difference in apparent density between the portions differing in terms of compressive hardness is 0.003 g/cm3 or less.
[3] The net structure according to [1] or [2], wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer.
[4] The net structure according to [1] or [2], wherein the number of junction points (pieces/g) differs by 7% or more between the portions differing in terms of compressive hardness.
[5] The net structure according to [1] or [2], wherein the portions differing in terms of compressive hardness have a difference in fiber diameter of 10% or less.
[6] The net structure according to [1] or [2], wherein in a melting curve measured with a differential scanning calorimeter (DSC), an endothermic peak top temperature appearing at a melting point or lower differs by 1° C. or more between the portions differing in terms of compressive hardness of the net structure.
[7] The net structure according to [6], wherein in a melting curve measured with a differential scanning calorimeter (DSC), an endothermic peak top temperature appearing at a melting point or lower differs by 2° C. or more between the portions differing in terms of compressive hardness of the net structure.
[8] A method for manufacturing a net structure, comprising: an extruding step of supplying a dried thermoplastic elastomer to an extruder from a hopper, measuring a certain amount of a melt-extruded thermoplastic resin with a gear pump, then supplying the thermoplastic resin to a nozzle having a plurality of orifices, and ejecting the thermoplastic resin downward to make the thermoplastic resin naturally drop; and a cooling and forming step of sandwiching ejected filaments in a molten state by a pair of take-off conveyers disposed on cooling water in a water tank, retaining the filaments to form loops, conveying the formed loops into the water tank while the loops come into contact with each other, and cooling the loops with the cooling water to form a random three-dimensional form, wherein
[9] The method for manufacturing a net structure according to [8], wherein a speed of the cooling water is partially varied.
[10] The method for manufacturing a net structure according to [8] or [9], wherein
According to the present invention, since hardness can be reduced without varying the apparent density, it is possible to vary the hardness without impairing the texture or increasing the product weight, and it is possible to manufacture a net structure with clear boundaries of hardness.
Hereinafter, the present invention will be specifically described with reference to the drawings. However, the present invention is not limited by the examples that have been shown, and can also be carried out with modifications being made as appropriate within the scope of the gist of the present invention, and any of these modifications are included in the technical scope of the present invention.
The net structure of the present invention is a net structure having a three-dimensional random loop junction structure composed of thermoplastic elastomer continuous filaments. The net structure includes portions differing in terms of compressive hardness by 5% or more zonally, and the portions differing in terms of compressive hardness have a difference in apparent density of 0.005 g/cm3 or less. In other words, the net structure of the present invention has at least two portions differing in terms of compressive hardness, and a difference in apparent density between the two portions differing in terms of compressive hardness is 0.005 g/cm3 or less.
The width of the zonal region is preferably 5 cm or more, and may be in the width direction or longitudinal direction of the net structure. Appropriate width and position may be determined according to the application. For example, in chair cushioning applications, there is a need to soften the thigh area, and the width of the zonal region is preferably about 15 cm. Also, in mattress applications, there is a need to soften the shoulder area, and the width of the zonal region is preferably about 30 cm. Furthermore, in edge seat mattress applications, there is a need to soften the central part, and the width of the zonal region is preferably about 50 cm.
In the present invention, the difference in apparent density between the portions differing in terms of compressive hardness is 0.005 g/cm3 or less, preferably 0.003 g/cm3 or less, more preferably 0.002 g/cm3 or less, and particularly preferably 0.001 g/cm3. When the difference in apparent density between the portions differing in terms of compressive hardness is within the above range, the apparent density of the portions differing in terms of compressive hardness can be regarded as substantially the same.
In the net structure of the present invention, a continuous filament formed of thermoplastic elastomer is meandered to form a random loop, and the filaments are brought into contact with each other, and the contact parts are fused to form a three-dimensional net structure. Accordingly, even when a large deformation is given with a very large stress, the entire net structure consisting of three-dimensional random loops integrated by fusion deforms and absorbs the stress, and upon release of the stress, the structure can restore the original form by the elasticity of the thermoplastic resin. Here, by partially changing cooling and solidification conditions and manufacturing conditions in the net structure manufacturing process described above, it is possible to manufacture a net structure in which the number of contact points is varied zonally and the hardness is varied.
The thermoplastic elastomer of the present invention is not particularly limited as long as it is capable of meandering the filament, bringing the filaments into contact with each other, and fusing contact parts. Examples of such thermoplastic elastomer include polyester-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, thermoplastic ethylene vinyl acetate copolymer elastomers, and the like. Among these, polyester-based thermoplastic elastomers are preferred because they are excellent in compression durability and heat resistance.
As the polyester-based thermoplastic elastomer, a polyester ether block copolymer having thermoplastic polyester as a hard segment and polyalkylene diol as a soft segment, or a polyester ester block copolymer having an aliphatic polyester as a soft segment can be exemplified.
As the polyester ether block copolymer, a ternary block copolymer composed of dicarboxylic acid, a diol component, and polyalkylene diol can be exemplified. As the dicarboxylic acid, at least one of dicarboxylic acids selected from aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, and diphenyl-4,4′-dicarboxylic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dimer acid, or ester forming derivatives thereof and so on can be mentioned.
As the diol component, at least one of diol components selected from aliphatic diols such as 1,4-butanediol, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, and hexamethylene glycol, alicyclic diols such as 1,1-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, or ester forming derivatives thereof and so on can be mentioned.
As the polyalkylene diol, at least one of polyalkylene diols such as glycols including polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and ethylene oxide-propylene oxide copolymer having a number average molecular weight of about 300 to 5000 can be mentioned.
As the polyester ester block copolymer, a ternary block copolymer composed of dicarboxylic acid, a diol component, and polyester diol can be exemplified. As the dicarboxylic acid and the diol component, the above dicarboxylic acids and diol components can be exemplified. As the polyester diol, at least one of polyester diols such as polylactone having a number average molecular weight of about 300 to 5000 can be mentioned.
Considering thermal adhesiveness, hydrolysis resistance, stretchability, heat resistance, and so on, the polyester ether block copolymer is particularly preferably a ternary block copolymer composed of terephthalic acid and/or naphthalene 2,6-dicarboxylic acid as the dicarboxylic acid, 1,4-butanediol as the diol component, and polytetramethylene glycol as the polyalkylene diol.
Also, the polyester ester copolymer is particularly preferably a ternary block copolymer composed of terephthalic acid and/or naphthalene 2,6-dicarboxylic acid as the dicarboxylic acid, 1,4-butanediol as the diol component, and polylactone as the polyester diol. In special cases, those incorporating a polysiloxane-based soft segment can also be used.
The soft segment content of the polyester-based thermoplastic elastomer of the present invention is preferably 15 mass % or more, more preferably 25 mass % or more, further preferably 30 mass % or more, and particularly preferably 40 mass % or more from the viewpoint of excellent compression durability, and is preferably 80 mass % or less, and more preferably 70 mass % or less from the viewpoint of ensuring hardness and excellent heat resistance and flattening resistance.
The polyolefin-based thermoplastic elastomer in the present invention is preferably an ethylene/α-olefin copolymer formed by copolymerizing ethylene and α-olefin, and is more preferably a multi-block copolymer composed of ethylene and α-olefin, which is an olefin block copolymer. A multi-block copolymer composed of ethylene and α-olefin is more preferred because with a general random copolymer, the linking chain length of the main chain is short, the crystal structure is difficult to be formed, and the durability deteriorates. From this point of view, α-olefin to be copolymerized with ethylene is preferably an α-olefin having 3 or more carbons.
Here, examples of the α-olefin having 3 or more carbons include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, and 1-eicocene, and preferred examples include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, and 1-eicocene. Two or more of these may be used.
The random copolymer, which is an ethylene-α-olefin copolymer of the present invention, can be obtained by copolymerizing ethylene and α-olefin using a catalytic system basically configured by a specific metallocene compound and an organometallic compound, and the multi-block copolymer can be obtained by copolymerizing ethylene and α-olefin using a chain shuttling reaction catalyst. If necessary, two or more polymers polymerized by the above method and polymers such as hydrogenated polybutadiene or hydrogenated polyisoprene may be blended.
In the ethylene-α-olefin copolymer of the present invention, the percentage of ethylene is preferably 70 mol % or more and 95 mol % or less, and the percentage of α-olefin having 3 or more carbons is preferably 5 mol % or more and 30 mol % or less. Generally, it is known that polymer compounds acquire elastomeric properties because there are a hard segment and a soft segment within the polymer chain. In the polyolefin thermoplastic elastomer of the present invention, it is conceivable that ethylene plays the role of a hard segment, and α-olefin having 3 or more carbons plays the role of a soft segment. Therefore, if the percentage of ethylene is less than 70 mol %, the amount of the hard segment is little, so that the recovery performance of rubber elasticity decreases. The percentage of ethylene is more preferably 75 mol % or more, and further preferably 80 mol % or more. On the other hand, if the percentage of ethylene exceeds 95 mol %, the amount of the soft segment is little, so that elastomeric properties are less likely to be exhibited, and cushioning performance is poor. The percentage of ethylene is more preferably 93 mol % or less, and further preferably 90 mol % or less.
As the polyurethane-based thermoplastic elastomer in the present invention, polyurethane elastomers can be exemplified as representative examples. The polyurethane elastomers are obtained by subjecting a prepolymer with isocyanate groups at both terminals, which is obtained by reacting a polyether and/or polyester with a hydroxyl group at a terminal, having a number average molecular weight of 1000 to 6000 and a polyisocyanate mainly based on an organic diisocyanate, to chain extension by a polyamine mainly based on diamine in the presence or absence of an ordinary solvent (dimethylformamide, dimethylacetamide, etc.).
As the polyester and/or polyether, polybutylene adipate copolymerized polyesters, polyalkylenediols such as glycols including polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and an ethylene oxide-propylene oxide copolymer, having a number average molecular weight of about 1000 to 6000, preferably 1300 to 5000, are preferred.
As the polyisocyanate, conventionally known polyisocyanates may be used. An isocyanate mainly based on diphenylmethane 4,4′-diisocyanate may be used, and a conventionally known triisocyanate or the like may be added in a trace amount as necessary. As the polyamine, a known diamine such as ethylenediamine or 1,2-propylenediamine may be mainly used, and a trace amount of triamine or tetramine may be used together as necessary. These polyurethane-based thermoplastic elastomers may be used alone, or two or more of these may be used in combination.
The soft segment content of the polyurethane-based thermoplastic elastomer in the present invention is preferably 15 mass % or more, more preferably 25 mass % or more, further preferably 30 mass % or more, and most preferably 40 mass % or more from the viewpoint of excellent compression durability, and is preferably 80 mass % or less, and more preferably 70 mass % or less from the viewpoint of ensuring hardness and excellent heat resistance and flattening resistance.
As a polyamide-based elastomer in the present invention, a copolymer of a polyamide as a hard segment and a polyol as a soft segment can be mentioned. As the polyamide, which is a hard segment, at least one or more of polyamide oligomers obtained from a reaction of a lactam compound and dicarboxylic acid, or a reaction of diamine and dicarboxylic acid can be mentioned. As the polyol which is a soft segment, at least one or more of polyether polyols, polyester polyols, polycarbonate polyols, and so on can be mentioned.
As the lactam compound, at least one or more of aliphatic lactams having 5 to 20 carbon atoms, such as γ-butyrolactam, ¿-caprolactam, ω-heptalactam, ω-undecalactam, and ω-lauryl lactam can be mentioned.
As the dicarboxylic acid, at least one or more of dicarboxylic acid compounds including aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecane diacid, and so on, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and orthophthalic acid can be mentioned.
As the diamine, at least one or more of aliphatic diamines such as ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecanemethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, and 3-methylpentamethylenediamine, or aromatic diamines such as meta-xylenediamine can be mentioned.
Regarding the polyol, as the polyether polyol, at least one or more of polyalkylene diols such as glycols including polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and an ethylene oxide-propylene oxide copolymer, having a number average molecular weight of about 300 to 5000 can be mentioned. Also, as the polycarbonate diol, reaction products of a low molecular weight diol and a carbonate compound, having a number average molecular weight of about 300 to 5000 can be mentioned.
As the low molecular weight diol, at least one or more of aliphatic diols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol, and alicyclic diols such as cyclohexanedimethanol and cyclohexanediol can be mentioned.
As the carbonate compound, at least one or more of dialkyl carbonates, alkylene carbonates, and diaryl carbonates can be mentioned. As the polyester polyol, at least one or more of polyester diols such as polylactone with a number average molecular weight of about 300 to 5000 can be mentioned.
The soft segment content of the polyamide-based thermoplastic elastomer of the present invention is preferably 5 mass % or more, more preferably 10 mass % or more, further preferably 15 mass % or more, and most preferably 20 mass % or more from the viewpoint of excellent compression durability, and is preferably 80 mass % or less, and more preferably 70 mass % or less from the viewpoint of ensuring hardness and excellent heat resistance and flattening resistance.
As the thermoplastic ethylene-vinyl acetate copolymer elastomer of the present invention, the polymer constituting the net structure preferably has a vinyl acetate content of 1 to 35%. Since there is a concern that the rubber elasticity may be poor if the vinyl acetate content is small, a vinyl acetate content is preferably 1% or more, more preferably 2% or more, and further preferably 3% or more. Rubber elasticity is excellent when the vinyl acetate content increases, but for the fear that melting point decreases and heat resistance may be poor, a vinyl acetate content is preferably 35% or less, more preferably 30% or less, and further preferably 26% or less.
The thermoplastic ethylene-vinyl acetate copolymer elastomer may be copolymerized with an α-olefin having 3 or more carbon atoms. Here, examples of the α-olefin having 3 or more carbons include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, and 1-eicocene, and preferred examples include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, and 1-eicocene. Two or more of these may be used.
The continuous filament constituting the net structure of the present invention may be composed of a mixture of two or more different thermoplastic elastomers according to the purpose. When the continuous filament is composed of a mixture of two or more different thermoplastic elastomers, at least one thermoplastic elastomer selected from the group consisting of polyester-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers is contained preferably 50 mass % or more, more preferably 60 mass % or more, and particularly preferably 70 mass % or more.
In the thermoplastic elastomer of the continuous filament constituting the net structure of the present invention, various additives may be blended depending on the purpose. Examples of the additives that can be added include phthalic acid ester-based, trimellitic acid ester-based, fatty acid-based, epoxy-based, adipic acid ester-based, polyester-based, and the like plasticizers, well-known hindered phenol-based, sulfur-based, phosphorus-based, amine-based, and the like antioxidants, hindered amine-based, triazole-based, benzophenone-based, benzoate-based, nickel-based, salicyl-based, and the like light stabilizers, antistatic agents, molecular weight regulators such as peroxide, compounds having a reactive group such as epoxy-based compounds, isocyanates-based compounds, carbodiimide-based compounds, metal inactivators, organic and inorganic nucleating agents, neutralizers, antacids, antibacterial agents, fluorescent brighteners, fillers, flame retardants, flame retardant auxiliaries, organic and inorganic pigments, and so on.
The apparent density of the net structure of the present invention is preferably 0.005 g/cm3 or more and 0.20 g/cm3 or less, more preferably 0.01 g/cm3 or more and 0.18 g/cm3 or less, and further preferably 0.02 g/cm3 or more and 0.15 g/cm3 or less. The apparent density of less than 0.005 g/cm3 is not preferred because the hardness required in use as a cushioning material cannot be maintained, and the texture also deteriorates. On the other hand, the apparent density exceeding 0.20 g/cm3 is not preferred because not only the hardness is too large to be suited for a cushion material, but the weight of the cushion material as a whole also becomes excessively heavy.
The thickness of the net structure of the present invention is preferably 5 mm or more, and more preferably 10 mm or more. If the thickness is less than 5 mm, the net structure, when used as a cushioning material, is too thin and feeling of flooring may arise. In relation to the manufacturing device, the upper limit of the thickness is preferably 300 mm or less, more preferably 200 mm or less, and further preferably 120 mm or less.
The fiber diameter of fibers forming the net structure of the present invention is preferably 0.1 mm or more and 3.0 mm or less. If the fiber diameter is less than 0.1 mm, the fiber is too thin, and it becomes difficult to ensure the required hardness as a net structure. If the fiber diameter exceeds 3.0 mm, the hardness of the net structure can be ensured, but the net structure becomes rough, and compression durability may be poor.
A 25% compressive hardness of the net structure of the present invention is not particularly limited, but the hardness of the lowest hardness site is preferably 5 kg/φ200 mm or more. The 25% compressive hardness is a stress at 25% compression in the stress-strain curve obtained by compressing a net structure up to 75% with a φ200 mm diameter circular compression plate. If the 25% compressive hardness is less than 5 kg/φ200 mm, sufficient elasticity cannot be obtained, and comfortable cushioning property is impaired. The 25% compressive hardness is more preferably 10 kg/φ200 mm or more, and particularly preferably 15 kg/200 mm or more. Although the upper limit is not particularly set, the 25% compressive hardness is preferably 50 kg/φ200 mm or less, more preferably 45 kg/φ200 mm or less, and particularly preferably 40 kg/φ200 mm or less. The 25% compressive hardness of 50 kg/φ200 mm or more is not preferred from the viewpoint of cushioning property.
The continuous filament constituting the net structure of the present invention may be a filament of a composite form combined with another thermoplastic resin as long as the object of the present invention is not impaired. Examples of the composite form include a sheath-core type composite filament, a side-by-side type composite filament, and an eccentric sheath-core type composite filament, in the case where the filament itself is composited.
The present inventors found that regarding the net structure of the present invention, difference, in the number of junction points between portions differing in terms of compressive hardness, of 7% or more results in variation in hardness of 5% or more. A junction point indicates a fusion part between two filaments constituting the net structure. Assuming that a net structure is cut into a size of 5 cm in the longitudinal direction and 5 cm in the width direction and into a rectangular parallelepiped shape containing two superficial surfaces of the sample but not containing an ear part of the sample to prepare a rectangular parallelepiped individual piece, the number of junction points (unit: pieces/g) per unit weight is a value obtained by dividing the number of junction points (unit: pieces/cm3) per unit volume in the individual piece by the apparent density (unit: g/cm3) of the individual piece.
The method for measuring the number of junction points includes detaching fusion parts by pulling two filaments, and measuring the number of times of detachment. As the number of junction points decreases, the distance between the contact points increases, and the hardness decreases. The mechanism of the technique for changing the number of junction points described above is still unknown, but as in the manufacturing method described later, it is possible to control the number of junction points with any of the following (a) to (d), for example.
When the number of contact points is changed by the fiber diameter, the difference in fiber diameter is preferably 10% or less. When the difference in fiber diameter exceeds 10%, the difference in apparent density is sometimes 5% or more, and in such a case, problems similar to those by the technique of varying the hardness by variation in apparent density occur.
When the number of contact points is changed by varying the nozzle temperature, the difference in nozzle temperature is preferably 100° C. or less. If the difference is 100° C. or more, the resin deteriorates and cannot exert its original performance.
For the portions differing in terms of hardness of the net structure, difference in endothermic peak top temperature appearing at the melting point or lower in the melting curve measured with a differential scanning calorimeter (DSC) is preferably 1° C. or more, and more preferably 2° C. or more. Although difference in hardness can be imparted even with the difference of 1° C. or less, difference of 1° C. or more makes it possible to impart an even larger difference in hardness.
The endothermic peak at the melting point or lower appears by an annealing treatment at a temperature lower than the melting point by 10° C. or more, and heat resistance and flattening resistance are significantly improved compared to those without an endothermic peak. This mechanism is unknown, but the temperature difference at the peak top is due to the difference in cooling of the resin described later, and the higher the cooling speed, the lower the peak top. When the annealing treatment is not performed, an endothermic peak does not appear at temperatures of lower than the melting point by 20° C. or more. Inferring from this, it is also conceivable that hard segments are rearranged due to annealing, pseudocrystallization-like crosslinking points are formed, and heat resistance and flattening resistance are improved. Hereafter, this annealing process may be called “pseudocrystallization treatment”. This pseudocrystallization treatment effect is also effective for polyolefin-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and polyurethane-based thermoplastic elastomers.
Hereinafter, the method for manufacturing the net structure of the present invention is described. The thermoplastic elastomer is preferably dried so that the moisture content is 300 ppm or less. If the moisture content exceeds 300 ppm, resin deterioration and mixing of air bubbles occur. A manufacturing process includes: an extruding step in which a dried so that the moisture content is 300 ppm or less thermoplastic elastomer is supplied to an extruder from a hopper, a certain amount of a melt-extruded thermoplastic resin is measured with a gear pump, and then the thermoplastic resin is supplied to a nozzle having a plurality of orifices, and ejected downward to naturally drop; and a cooling and forming step in which ejected filaments in a molten state are sandwiched by a pair of take-off conveyers disposed on cooling water in a water tank, and retained to cause formation of loops, and the formed loops are conveyed into the water tank while the loops come into contact with each other, and cooled with the cooling water to form a random three-dimensional form. In this method, it is possible to manufacture a net structure having hardness varying among sites and substantially no difference in apparent density by changing a combination of an orifice diameter of a nozzle and an apparent density of the orifice used in the extrusion step. The combination of the orifice diameter of the nozzle and the apparent density of the orifice must be designed so that the apparent density per unit area does not vary. A discharge amount from one orifice can be calculated from the orifice diameter and the melt viscosity of the thermoplastic elastomer, and by using the product with the number of holes per unit area, the discharge amount per unit area can be calculated.
The net structure manufacturing device according to the present invention has a nozzle having a discharge hole that pushes out a molten thermoplastic resin in a filamentary form, a water tank located below the nozzle, a conveying device provided in the water tank to convey a net structure having a filamentary resin, and a water ejection device provided in the tank and ejecting water in a predetermined direction. The conveying device consists of at least a first conveying device and a second conveying device. There is a net structure between the first conveying device and the second conveying device, and the net structure between the conveying devices does not exist on the extension line in the eject direction of water of the water ejection device.
The nozzle 10 has discharge holes 11 that push a molten thermoplastic resin into a filamentary form. That is, a thermoplastic resin melted by heating is extruded from the discharge holes 11 of the nozzle 10 to form a filamentary resin 12.
The discharge holes 11 of the nozzle 10 may be arranged in one line, but is preferably arranged in a plurality of lines. Since the nozzle 10 has a plurality of discharge holes 11, a plurality of filaments of resin 12 can be formed at once, and hence it is possible to enhance the production efficiency of a net structure 60. The number of discharge holes 11 that the nozzle 10 has can be adjusted according to the hardness and the cushioning property of the net structure 60 to be manufactured.
The cross-sectional shape of the outlet of each discharge hole 11 is not particularly limited, and may be, for example, round, oval, polygonal and so on. Among these, the cross-sectional shape of the outlet of the discharge hole 11 is preferably round or oval. Since the discharge hole 11 is configured in this way, the cross-sectional shape of the filamentary resin 12 extruded from the discharge hole 11 also becomes round or oval. Thus, in formation of the three-dimensional random loop junction structure described above, the area where the filaments of resin 12 come into contact with each other is increased, and the net structure 60 having high elasticity and durability can be manufactured.
The cross-sectional shape of the filamentary resin 12 extruded from the discharge hole 11 may be solid or hollow. In order to make the cross-sectional shape of the filamentary resin 12 be hollow, for example, a structure having a core part like a mandrel inside the discharge hole 11 may be employed. Specifically, regarding the cross-sectional shape of the outlet of the discharge hole 11, a so-called C-shaped nozzle in which the inside and the outside of the discharge hole 11 are partially communicated with each other, and a so-called 3-point bridge-shaped nozzle in which a bridge is provided at the discharge hole 11 to divide the discharge hole 11 in the circumferential direction can be mentioned.
The length in the major axial direction of the cross-sectional shape of the outlet of the discharge hole 11 is preferably 0.1 mm or more, more preferably 0.5 mm or more, and further preferably 1.0 mm or more. By setting the lower limit value of the length in the major axial direction of the cross-sectional shape of the outlet of the discharge hole 11 in this way, it is possible to enhance the durability of the net structure 60, and it is possible to realize the net structure 60 that is durable to repeated compression. The length in the major axial direction of the cross-sectional shape of the outlet of the discharge hole 11 is preferably 10 mm or less, more preferably 7 mm or less, and further preferably 5 mm or less. By setting the upper limit value of the length in the major axial direction of the cross-sectional shape of the outlet of the discharge hole 11 in this way, it is possible to manufacture the net structure 60 with excellent cushioning property.
By changing the combination of the size of the cross-sectional shape of the outlet and the hole apparent density of the discharge hole 11 of the nozzle 10, it is possible to manufacture a net structure having hardness varying among sites and substantially no difference in apparent density. The combination of the orifice diameter and the orifice apparent density of the nozzle must be designed so that the apparent density per unit area does not vary. A discharge amount from one orifice can be calculated from the orifice diameter and the melt viscosity of the thermoplastic elastomer, and by the product with the number of holes per unit area, the discharge amount per unit area can be calculated.
The water tank 20 is located below the nozzle 10 and is configured to be capable of receiving the filamentary resin 12 extruded from the discharge hole 11 of the nozzle 10. The water tank 20 has water for cooling the filamentary resin 12 extruded from the discharge hole 11 of the nozzle 10. The filamentary resin 12 extruded from the discharge hole 11 of the nozzle 10 forms a random loop by landing on the water surface in the water tank 20 and meandering, and by coming into contact with an adjacent random loop in a molten state, forms a structure in which the random loops are joined together in a three-dimensional direction, and at the same time, the structure is fixed by being cooled with water. In this way, the net structure 60 is obtained.
The conveying device 30 is provided in the water tank 20 and conveys the net structure 60 having the filamentary resin 12. In other words, the conveying device 30 conveys, within the water tank 20, the net structure 60 having the filamentary resin 12 that is extruded from the discharge hole 11 of the nozzle 10 and received in the water tank 20. It is preferred that the conveying device 30 conveys the net structure 60 from the water surface of the water tank 20 toward the bottom of the water tank 20.
The conveying device 30 is composed of at least a first conveying device 31 and a second conveying device 32, and the net structure 60 is present between the first conveying device 31 and the second conveying device 32. Since the conveying device 30 is configured in this way, the net structure 60 can be conveyed while it is sandwiched between the first conveying device 31 and the second conveying device 32. Thus, it is possible to make the net structure 60 having a coordinated surface and constant thickness.
The type of the conveying device 30 is not particularly limited, and for example, conveyers such as a belt conveyer, a net conveyer, a slat conveyer and the like can be mentioned. Details of the conveying device 30 will be described later.
As a method for partially varying the cooling speed of the resin in the cooling step, a method of partially varying the temperature of the cooling water, and/or varying the speed of the cooling water can be mentioned. In order to partially vary the temperature of the cooling water, heated or cooled cooling water may be partially supplied from above the conveying device.
The water ejection device 40 is provided above the conveying device 30 and ejects water in a predetermined direction. The net structure 60 between the conveyers 30 does not exist on the extension in the water eject direction of the water ejection device 40. In order to obtain sufficient difference in cooling speed, it is preferred that the water temperature difference between the water surface temperature in the part where filaments land on the water at the time when the cooling water is not ejected, and the cooling water to be ejected is 5° C. or more. If the water temperature difference is less than 5° C., sufficient difference in the number of contact points may not be obtained. Also, it is more preferred that the water temperature difference is 10° C. or more. If the water temperature difference is less than 10° C., the temperature difference in endothermic peak top appearing at the melting point or lower may not be 1° C. or more.
The water amount of the cooling water supplied from above the conveying device is preferably 0.04 L/min or more and 0.9 L/min or less per 1 cm of width of the conveying device. If the amount of the cooling water is less than 0.04 L/min, it is impossible to sufficiently improve the cooling speed of the resin. If the amount of the cooling water is more than 0.9 L/min, molding defect of the surface of the net structure occurs, and the quality of the surface deteriorates. Also, cooling of the resin may be achieved by partially varying the speed of the cooling water. The water ejection device 40 is disposed at a desired position where the hardness is lowered zonally in the net structure, and is preferably disposed at an upper position of 0.1 mm or more and 100 mm or less above the water surface of the water tank 20.
As shown in
Meanwhile, as shown in
As shown in
Only one water ejection device 43 may be provided, or a plurality of water ejection devices 43 may be provided. The water amount ejected from the eject device 43 is preferably 0.6 L/min or more and 3.0 L/min or less per 1 cm of the width of the water ejection device. By the ejected water, the flow rate of the water partially varies, and it becomes possible to partially vary the cooling speed of the thermoplastic elastomer. It is preferred that the ejection position of the cooling water is located 0.1 mm or more and 100 mm or less below the water surface in the water tank.
It is preferred that the upper end part of the conveying device 30 is located above the water surface of the water tank 20. Since the conveying device 30 is disposed in this manner, when the filamentary resin 12 extruded from the discharge hole 11 of the nozzle 10 comes into contact with the water in the water tank 20, it is possible to prevent the filamentary resin 12 from moving freely on the water surface and to prevent the thickness of the net structure 60 from being excessively large.
It is preferred that the conveying device 30 has a conveyor belt 33 and a drive roller 34. Examples of the conveyor belt 33 include a flat belt made of rubber or resin, a net conveyor belt made into a mesh shape by continuously braiding or weaving metal wires, and a slat conveyor belt in which a metallic plate is continuously attached to the conveyer chain.
Among these, the conveyor belt 33 is preferably a net conveyor belt because of excellent holding performance and excellent water permeability performance. That is, it is preferred that the conveying device 30 is a net belt conveying device having a mesh-like belt and a drive roller. Since the conveying device 30 is configured in this manner, water can pass through the conveying device 30, and the conveying device 30 hardly interferes with the convection of water in the water tank 20 by the water ejection device 40, and thus the cooling efficiency of the net structure 60 can be enhanced.
It is preferred that the conveyor belt 33 is endless. Since the conveyor belt 33 is configured to be endless, the endless conveyor belt 33 rotates without interruption as the drive roller 34 rotates. Thus, it is possible to continuously operate the conveying device 30, and it is possible to conduct conveyance of the net structure 60 efficiently.
There are a plurality of drive rollers 34, and the drive rollers 34 are preferably provided in an upper part and a lower part inside the endless conveyor belt 33, respectively. In other words, it is preferred that an upper drive roller 34a is disposed in the upper part inside the conveyor belt 33, and a lower drive roller 34b is disposed in the lower part inside the conveyor belt 33. Since the drive roller 34 is configured in this manner, the conveyor belt 33 becomes less likely to bend, and it is possible to prevent the conveyor belt 33 from idling by rotation of the driving roller 34 and causing the conveying device 30 to malfunction.
It is preferred that the distance between the lower drive roller 34b of the first conveying device 31 and the lower drive roller 34b of the second conveying device 32 is smaller than the distance between the upper drive roller 34a of the first conveying device 31 and the upper drive roller 34a of the second conveying device 32. That is, it is preferred that the distance between the first conveying device 31 and the second conveying device 32 is smaller in the lower part than in the upper part, and the distance decreases as it goes downward. Since the conveying device 30 is configured in this manner, it is possible to sandwich the net structure 60 in the lower part of the conveying device 30, and the filamentary resin 12 and the net structure 60 can be easily drawn into the water tank 20, and hence cooling of the net structure 60 becomes easy to perform.
It is preferred that the net structure manufacturing device 1 has a net structure towing device 50 that tows and pulls up the net structure 60 from the water tank 20. Since the net structure manufacturing device 1 has the net structure towing device 50, the net structure 60 can be automatically pulled up from the water tank 20 and transferred to the drying step of the net structure 60 after cooling of the net structure 60. Therefore, it is possible to increase the productivity of the net structure 60.
Water in the water tank 20 may be drained and water at low temperature may be newly supplied to the water tank 20. Regarding drainage of water from the water tank 20, although not shown in figure, the drainage may be performed, by so-called overflow in which water is drained from piping or the like disposed in an upper part of the water tank 20.
(1) Thickness and Apparent Density (Mm and g/cm3)
Four samples were cut out into a size of 10 cm in the width direction, 10 cm in the length direction, and the sample thickness, and were left without loading for 24 hours. After that, for each sample with the thin fiber surface side facing up, a height at one point was measured by a thickness meter FD-80N manufactured by KOBUNSHI KEIKI CO., LTD. using a circular measuring instrument with an area of 15 cm2, and an average value of four samples was defined as a thickness. The above sample was weighed on an electronic balance, and an average value of weight of the four samples was defined as a weight. Also, an apparent density was calculated from the weight and the thickness using the following formula.
(Apparent density)=(Weight)/(Thickness×10×10): unit g/cm3
The sample was cut into a size of 10 cm in the width direction, 10 cm in the length direction, and the sample thickness, and ten fiber filaments with a length of about 5 mm were randomly collected from the cut cross section. The collected filaments were cut in the circular cutting direction, placed on the cover glass in the condition that the filaments stand in the direction of the fiber axis, and a fiber cross-sectional photograph in the circular cutting direction was obtained with an optical microscope set to an appropriate magnification. A diameter of the fiber was determined from the obtained fiber cross-sectional photograph, and the average value of n=10 was defined as a fiber diameter (unit: mm). The surface of the net structure is flattened to obtain smoothness, and the fiber cross section may be deformed. Therefore, a sample was not collected in a region within 2 mm from the surface of the net structure. When the cross-sectional shape of a filament is a hollow cross-sectional shape or an irregular cross-sectional shape, the outer circumferential length of the cross-sectional shape of the filament was determined from the obtained fiber cross-sectional photograph, the diameter of a circle having an outer circumference length equal to the obtained outer circumferential length was determined by calculation, and the length of the diameter was defined as a fiber diameter.
First, a sample was cut into a size of 5 cm in the longitudinal direction and 5 cm in the width direction and in a shape of a rectangular parallelepiped containing two superficial surfaces of the sample but not containing an ear part of the sample to prepare an individual piece. Next, after measuring the height of the rectangular parallelepiped of the individual piece, the volume (unit: cm3) was determined. By dividing the weight (unit: g) of the sample by the volume, an apparent density (unit: g/cm3) was calculated. Next, the number of junction points of the piece was counted, and the number was divided by the volume to calculate the number of junction points per unit volume (unit: pieces/cm3). By dividing the number of junction points per unit volume by the apparent density, the number of junction points per unit weight (unit: pieces/g) was calculated. The junction point is a fusion part between two filaments, and the number of junction points was measured by pulling the two filaments to detach the fusion parts. Also, the number of junction points per unit weight was an average value of n=2.
A sample was cut into a size of 30 cm in the longitudinal direction and 30 cm in the width direction and in a shape of a rectangular parallelepiped containing two superficial surfaces of the sample but not containing an ear part of the sample, and was compressed to 75% with a φ200 mm compression plate by using Tensilon manufactured by ORIENTEC to obtain a stress-distortion curve. The 25% compressive hardness is indicated by the stress at the time of 25% compression in the obtained stress-distortion (unit: kg/φ200). An average value of n=3 was adopted as 25% compressive hardness. The hardness difference ratio (unit: %) of portions with different hardnesses was calculated according to the following formula from the hardness of each site measured by the method described above.
Hardness difference ratio (%)=(Hardness in high hardness site-Hardness in low hardness site)/Hardness in high hardness site
For a sample cut into a size of 30 cm in the longitudinal direction and 30 cm in the width direction and in a shape of a rectangular parallelepiped containing two superficial surfaces of the sample but not containing an ear part of the sample, 30 panelists (5 men aged 20 to 39; 5 women aged 20 to 39; 5 men aged 40 to 59; 5 women aged 40 to 59; 5 men aged 60 to 80; and 5 women aged 60 to 80) touched the sample, and qualitatively evaluated the degree of unevenness felt in touching sensitively.
⊚: felt no unevenness, ∘: weakly felt unevenness, Δ: moderately felt unevenness, ×: strongly felt unevenness
As a polyester-based thermoplastic elastomer, dimethyl terephthalate (DMT) and 1,4-butanediol (1,4-BD) were loaded with a small amount of catalyst, and after ester exchange by a usual method, polytetramethylene glycol (PTMG) having a number average molecular weight of 1000 was added and polycondensed while the temperature was elevated and the pressure was reduced to generate a polyether ester block copolymer elastomer. After adding, mixing, and kneading 1 mass % of an antioxidant, the mixture was pelletized, and dried in a vacuum at 50° C. for 48 hours to obtain a polyester-based thermoplastic elastomer A-1. The polyester-based thermoplastic elastomer A-1 had a soft segment content of 40 mass % and a melting point of 198° C.
Using a nozzle in which orifices each being a triple-bridged hollow forming orifice having an outer diameter of 3 mm and an inner diameter of 2.6 mm are staggered at a hole-to-hole pitch in the width direction of 6 mm and a hole-to-hole pitch in the thickness direction of 5.2 mm on an effective surface having a length in the width direction of 66 cm and a length in the thickness direction of 46.8 mm (10 lines), the obtained polyester-based thermoplastic elastomer (A-1) was ejected downward of the nozzle at a spinning temperature (melting temperature) of 240° C., at a single hole discharge amount of 2.03 g/min. Cooling water was located at 27 cm below the nozzle surface, and a pair of stainless endless take-off conveyer nets with an opening width of 35 mm interval was located in such a manner that the conveyer nets partially come out above the water surface. On the take-off conveyer nets above the water surface, the molten ejected filament was meandered to form a loop, and a three-dimensional net structure was formed while the contact parts were fused. While both sides of the net structure in a molten state were sandwiched by the take-off conveyer nets, the net structure was drawn at a take-off speed of 2.88 m/min, in a center region of 30 cm into cooling water in the state that cooling water of about 16° C. was ejected at a flow rate of 0.8 L/min per a width of 1 cm from the position outside the conveyer nets and at 70 mm above the conveying device, and solidified to flatten both sides in the thickness direction. Thereafter, the net structure was cut into a predetermined size and subjected to a drying treatment with hot air at 110° C. for 35 minutes to obtain the net structure. The water surface temperature in the water tank (the part where filaments land on the water) when no cooling water was ejected was about 65° C., and the water temperature difference with respect to the ejected cooling water was about 49° C.
The obtained net structure was a net structure mainly composed of hollow cross-sectional fibers having a fiber diameter of 0.69 mm and a round cross-sectional shape. The average thickness of the net structure was 36.3 mm, the average thickness of the high hardness site was 36.2 mm, the average thickness of the low hardness site was 36.4 mm, the apparent density of the high hardness site was 0.035 g/cm3, the apparent density of the low hardness site was 0.035 g/cm3, the number of junction points in the high hardness site was 144 pieces/g, and the number of junction points in the low hardness site was 131 pieces/g. In the melting curve measured with a differential scanning calorimeter (DSC), an endothermic peak top temperature appearing at the melting point of the thermoplastic elastomer constituting the continuous filament or lower was 129.3° C. in the high hardness site and 126.5° C. in the low hardness site.
Regarding the obtained net structure, the 25% compressive hardness of the high hardness site was 9.6 kg/φ200, the 25% compressive hardness of the low hardness site was 7.7 kg/φ200, and poor texture was not felt in the panelist evaluation, and the evaluation was ⊚. Also, the weight was within the normal design range, and the boundary of hardness was clear. Results are summarized in Tables 1 to 3.
Using a nozzle in which orifices each being a triple-bridged hollow forming orifice having an outer diameter of 3 mm and an inner diameter of 2.6 mm are staggered at a hole-to-hole pitch in the width direction of 6 mm and a hole-to-hole pitch in the thickness direction of 5.2 mm on an effective surface having a length in the width direction of 66 cm and a length in the thickness direction of 46.8 mm (10 lines), the obtained polyester-based thermoplastic elastomer (A-1) was ejected downward of the nozzle at a spinning temperature (melting temperature) of 240° C., at a single hole discharge amount of 2.23 g/min. Cooling water was located at 25 cm below the nozzle surface, and a pair of stainless endless take-off conveyer nets with an opening width of 35 mm interval was located parallel with each other in such a manner that the conveyer nets partially come out above the water surface. On the conveyer nets above the water surface, the molten ejected filament was meandered to form a loop, and a three-dimensional net structure was formed while the contact parts were fused. While both sides of the net structure in a molten state were sandwiched by the take-off conveyer nets, the net structure was drawn at a take-off speed of 1.80 m/min, in a region of 33 cm on either side from the center into cooling water in the state that cooling water of about 15° C. was ejected at a flow rate of 1.8 L/min per a width of 1 cm from outside the conveyer nets, and solidified to flatten both sides in the thickness direction. Thereafter, the net structure was cut into a predetermined size and subjected to a drying treatment with hot air at 110° C. for 35 minutes to obtain the net structure. The water surface temperature in the water tank (the part where filaments land on the water) when no cooling water was ejected was about 75° C., and the water temperature difference with respect to the cooling water ejected from about 50 mm below the water surface was about 60° C.
The obtained net structure was a net structure mainly composed of hollow cross-sectional fibers having a fiber diameter of 0.72 mm and a round cross-sectional shape. The average thickness of the net structure was 35.8 mm, the average thickness of the high hardness site was 35.7 mm, the average thickness of the low hardness site was 35.8 mm, the apparent density of the high hardness site was 0.063 g/cm3, the apparent density of the low hardness site was 0.064 g/cm3, the number of junction points in the high hardness site was 248 pieces/g, and the number of junction points in the low hardness site was 198 pieces/g. In the melting curve measured with a differential scanning calorimeter (DSC), the endothermic peak top temperature appearing at the melting point of the thermoplastic elastomer constituting the continuous filament or lower was 129.1° C. in the high hardness site and 126.8° C. in the low hardness site.
Regarding the obtained net structure, the 25% compressive hardness of the high hardness site was 21.9 kg/φ200, the 25% compressive hardness of the low hardness site was 11.8 kg/φ200, and poor texture was not felt in the panelist evaluation, and the evaluation was ⊚. Also, the weight was within the normal design range, and the boundary of hardness was clear. Results are summarized in Tables 1 to 3.
Using a nozzle in which orifices each being a triple-bridged hollow forming orifice for thick fiber having an outer diameter of 5 mm and an inner diameter of 4.4 mm are staggered at a hole-to-hole pitch in the width direction of 9 mm and a hole-to-hole pitch in the thickness direction of 7.8 mm on an effective surface having a length in the width direction of 95 cm and a length in the thickness direction of 101.3 mm (14 lines), the obtained polyester-based thermoplastic elastomer (A-1) was ejected downward of the nozzle at a spinning temperature (melting temperature) of 240° C., at a single hole discharge amount of 2.81 g/min. Cooling water was located at 29 cm below the nozzle surface, and a pair of stainless endless take-off conveyer nets with an opening width of 85 mm interval was located parallel with each other in such a manner that the conveyer nets partially come out above the water surface. On the conveyer nets above the water surface, the molten ejected filament was meandered to form a loop, and a three-dimensional net structure was formed while the contact parts were fused. While both sides of the net structure in a molten state were sandwiched by the take-off conveyer nets, the net structure was drawn at a take-off speed of 1.35 m/min, in a center region of 30 cm into cooling water in the state that cooling water of about 15° C. was ejected at a flow rate of 2.1 L/min per a width of 1 cm from outside the conveyer nets, and solidified to flatten both sides in the thickness direction. Thereafter, the net structure was cut into a predetermined size and subjected to a drying treatment with hot air at 110° C. for 35 minutes to obtain the net structure. The water surface temperature in the water tank (the part where filaments land on the water) when no cooling water was ejected was about 80° C., and the water temperature difference with respect to the cooling water ejected from about 50 mm below the water surface was about 65° C.
The obtained net structure was a net structure mainly composed of hollow cross-sectional fibers having a fiber diameter of 0.76 mm and a round cross-sectional shape. The average thickness of the net structure was 83.5 mm, the average thickness of the high hardness site was 83.2 mm, the average thickness of the low hardness site was 84.1 mm, the apparent density of the high hardness site was 0.038 g/cm3, the apparent density of the low hardness site was 0.037 g/cm3, the number of junction points in the high hardness site was 149 pieces/g, and the number of junction points in the low hardness site was 133 pieces/g. In the melting curve measured with a differential scanning calorimeter (DSC), the endothermic peak top temperature appearing at the melting point of the thermoplastic elastomer constituting the continuous filament was 129.2° C. in the high hardness site and 126.7° C. in the low hardness site.
Regarding the obtained net structure, the 25% compressive hardness of the high hardness site was 20.3 kg/φ200, the 25% compressive hardness of the low hardness site was 16.0 kg/φ200, and poor texture was not felt in the panelist evaluation, and the evaluation was ⊚. Also, the weight was within the normal design range, and the boundary of hardness was clear. Results are summarized in Tables 1 to 3.
Using a nozzle in which orifices each having a solid circular cross-sectional shape with an outer diameter of 1 mm are staggered at a hole-to-hole pitch in the width direction of 6 mm and a hole-to-hole pitch in the thickness direction of 5.2 mm on an effective surface having a length in the width direction of 95 cm and a length in the thickness direction of 46.8 mm (10 lines), the obtained polyester-based thermoplastic elastomer (A-1) was ejected downward of the nozzle at a spinning temperature (melting temperature) of 240° C., at a single hole discharge amount of 1.1 g/min. Cooling water was located at 24 cm below the nozzle surface, and a pair of stainless endless take-off conveyer nets with an opening width of 25 mm interval was located parallel with each other in such a manner that the conveyer nets partially come out above the water surface. On the conveyer nets above the water surface, the molten ejected filament was meandered to form a loop, and a three-dimensional net structure was formed while the contact parts were fused. While both sides of the net structure in a molten state were sandwiched by the take-off conveyer nets, the net structure was drawn at a take-off speed of 2.17 m/min, in a center region of 40 cm into cooling water in the state that cooling water of about 14° C. was ejected at a flow rate of 1.8 L/min per a width of 1 cm from outside the conveyer nets, and solidified to flatten both sides in the thickness direction. Thereafter, the net structure was cut into a predetermined size and subjected to a drying treatment with hot air at 110° C. for 35 minutes to obtain the net structure. The water surface temperature in the water tank (the part where filaments land on the water) when no cooling water was ejected was about 60° C., and the water temperature difference with respect to the cooling water ejected from about 50 mm below the water surface was about 46° C.
The obtained net structure was a net structure mainly composed of round hollow cross-sectional fibers having a fiber diameter of 0.45 mm and a circular cross-sectional shape. The average thickness of the net structure was 26.1 mm, the average thickness of the high hardness site was 26.1 mm, the average thickness of the low hardness site was 26.2 mm, the apparent density of the high hardness site was 0.050 g/cm3, the apparent density of the low hardness site was 0.049 g/cm3, the number of junction points in the high hardness site was 306 pieces/g, and the number of junction points in the low hardness site was 187 pieces/g. In the melting curve measured with a differential scanning calorimeter (DSC), the endothermic peak top temperature appearing at the melting point of the thermoplastic elastomer constituting the continuous filament or lower was 128.9° C. in the high hardness site and 126.8° C. in the low hardness site.
Regarding the obtained net structure, the 25% compressive hardness of the high hardness site was 21.0 kg/φ200, the 25% compressive hardness of the low hardness site was 12.4 kg/φ200, and poor texture was not felt in the panelist evaluation, and the evaluation was ⊚. Also, the weight was within the normal design range, and the boundary of hardness was clear. Results are summarized in Tables 1 to 3.
A nozzle in which triple-bridge hollow forming orifices having an outer diameter of 3 mm and an inner diameter of 2.6 mm are staggered at a hole-to-hole pitch in the width direction of 6 mm and a hole-to-hole pitch in the thickness direction of 5.2 mm on an effective surface having a length in the width direction of 66 cm and a length in the thickness direction of 46.8 mm (10 lines) was used. The obtained polyester-based thermoplastic elastomer (A-1) was ejected downward of the nozzle at a single hole discharge amount of 2.03 g/min at a spinning temperature (melting temperature) of 270° C. for the high hardness site or at a spinning temperature (melting temperature) of 230° C. for the low hardness site. Cooling water was located at 27 cm below the nozzle surface, and a pair of stainless endless take-off conveyer nets with an opening width of 45 mm interval was located parallel with each other in such a manner that the conveyer nets partially come out above the water surface. On the conveyer nets above the water surface, the molten ejected filament was meandered to form a loop, and a three-dimensional net structure was formed while the contact parts were fused. While both sides of the net structure in a molten state were sandwiched by the take-off conveyer nets, the net structure was drawn at a take-off speed of 1.27 m/min, into the cooling water and solidified to flatten both sides in the thickness direction. Thereafter, the net structure was cut into a predetermined size and subjected to a drying treatment with hot air at 110° C. for 35 minutes to obtain the net structure.
The obtained net structure was a net structure mainly composed of hollow cross-sectional fibers having a fiber diameter in the high hardness site of 0.67 mm and a fiber diameter in the low hardness site of 0.69 mm and a round cross-sectional shape. The average thickness of the net structure was 45.3 mm, the average thickness of the high hardness site was 45.3 mm, the average thickness of the low hardness site was 45.2 mm, the apparent density of the high hardness site was 0.040 g/cm3, the apparent density of the low hardness site was 0.040 g/cm3, the number of junction points in the high hardness site was 202 pieces/g, and the number of junction points in the low hardness site was 181 pieces/g. In the melting curve measured with a differential scanning calorimeter (DSC), the endothermic peak top temperature appearing at the melting point of the thermoplastic elastomer constituting the continuous filament or lower was 129.1° C. in the high hardness site and in the low hardness site.
Regarding the obtained net structure, the 25% compressive hardness of the high hardness site was 11.5 kg/φ200, the 25% compressive hardness of the low hardness site was 9.9 kg/φ200, and poor texture was not felt in the panelist evaluation, and the evaluation was ⊚. Also, the weight was within the normal design range, and the boundary of hardness was clear. Results are summarized in Tables 1 to 3.
Orifices having the following shape were provided on the nozzle effective surface of 95 cm long in the width direction and 62.3 mm long in the thickness direction. For the high hardness site, triple-bridge hollow forming orifices having an outer diameter of 3 mm and an inner diameter of 2.6 mm were staggered (13 lines) at a hole-to-hole pitch in the width direction of 6 mm and a hole-to-hole pitch in the thickness direction of 5.2 mm. Also, for the low hardness site, triple-bridge hollow forming orifices for thick fiber having an outer diameter of 5 mm and an inner diameter of 4.4 mm were staggered (9 lines) at a hole-to-hole pitch in the width direction of 9 mm and a hole-to-hole pitch in the thickness direction of 7.8 mm, and the nozzle thus formed was used. The obtained polyester-based thermoplastic elastomer (A-1) was ejected downward of the nozzle at a spinning temperature (melting temperature) of 240° C. at a single hole discharge amount of 1.85 g/min for the high hardness site or at a single hole discharge amount of 4.00 g/min for the low hardness site. Cooling water was located at 20 cm below the nozzle surface, and a pair of stainless endless take-off conveyer nets with an opening width of 40 mm interval was located parallel with each other in such a manner that the conveyer nets partially come out above the water surface. On the conveyer nets above the water surface, the molten ejected filament was meandered to form a loop, and a three-dimensional net structure was formed while the contact parts were fused. Next, while both sides of the net structure in a molten state were sandwiched by the take-off conveyer nets, the net structure was drawn at a take-off speed of 2.60 m/min, into the cooling water and solidified. After flattening both sides in the thickness direction, the net structure was cut into a predetermined size and subjected to a drying treatment with hot air at 110° C. for 35 minutes to obtain the net structure.
The obtained net structure was a net structure mainly composed of hollow cross-sectional fibers with a round cross-sectional shape having a fiber diameter of 0.55 mm in the high hardness site and hollow cross-sectional fibers with a round cross-sectional shape having a fiber diameter of 0.93 mm in the low hardness site. The average thickness of the net structure was 40.1 mm, the average thickness of the high hardness site was 40.1 mm, the average thickness of the low hardness site was 40.1 mm, the apparent density of the high hardness site was 0.041 g/cm3, the apparent density of the low hardness site was 0.041 g/cm3, the number of junction points in the high hardness site was 294 pieces/g, and the number of junction points in the low hardness site was 144 pieces/g. In the melting curve measured with a differential scanning calorimeter (DSC), the endothermic peak top temperature appearing at the melting point of the thermoplastic elastomer constituting the continuous filament or lower was 129.0° C. in the high hardness site and in the low hardness site.
Regarding the obtained net structure, the 25% compressive hardness of the high hardness site was 15.0 kg/φ200, the 25% compressive hardness of the low hardness site was 13.1 kg/φ200, and poor texture was not felt in the panelist evaluation, and the evaluation was ⊚. Also, the weight was within the normal range, and also the boundary of hardness was clear. Results are summarized in Tables 1 to 3.
Using a nozzle in which orifices each being a triple-bridged hollow forming orifice for thick fiber having an outer diameter of 5 mm and an inner diameter of 4.4 mm are staggered at a hole-to-hole pitch in the width direction of 9 mm and a hole-to-hole pitch in the thickness direction of 7.8 mm on an effective surface having a length in the width direction of 95 cm and a length in the thickness direction of 54.6 mm (8 lines), the obtained polyester-based thermoplastic elastomer (A-1) was ejected downward of the nozzle at a spinning temperature (melting temperature) of 240° C., at a single hole discharge amount of 3.31 g/min. Cooling water was located at 30 cm below the nozzle surface, and a pair of stainless endless take-off conveyer nets with an opening width of 50 mm interval was located parallel with each other in such a manner that the conveyer nets partially come out above the water surface. On the conveyer nets above the water surface, the molten ejected filament was meandered to form a loop, and a three-dimensional net structure was formed while the contact parts were fused. While both sides of the net structure in a molten state were sandwiched by the take-off conveyer nets, the net structure was drawn at a take-off speed of 1.06 m/min for the part that is to be a high hardness site and 2.76 m/min for the part that is to be a low hardness site, into cooling water and solidified to flatten both sides in the thickness direction. Thereafter, the net structure was cut into a predetermined size and subjected to a drying treatment with hot air at 110° C. for 35 minutes to obtain the net structure.
The obtained net structure was a net structure mainly composed of hollow cross-sectional fibers having a fiber diameter of 0.87 mm and a round cross-sectional shape. The average thickness of the net structure was 48.9 mm, the average thickness of the high hardness site was 48.9 mm, the average thickness of the low hardness site was 49.0 mm, the apparent density of the high hardness site was 0.064 g/cm3, the apparent density of the low hardness site was 0.025 g/cm3, the number of junction points in the high hardness site was 151 pieces/g, and the number of junction points in the low hardness site was 98 pieces/g. In the melting curve measured with a differential scanning calorimeter (DSC), the endothermic peak top temperature appearing at the melting point of the thermoplastic elastomer constituting the continuous filament or lower was 129.2° C. in the high hardness site and in the low hardness site.
Regarding the obtained net structure, the 25% compressive hardness of the high hardness site was 27.5 kg/φ200, the 25% compressive hardness of the low hardness site was 6.2 kg/φ200, and in the panelist evaluation, poor texture was not felt in the high hardness site and the evaluation was ⊚, whereas in the low hardness site, poor texture was felt moderately or strongly, and the evaluation was × to Δ. Although the weight was within the normal design range, the weight was heavier due to the high apparent density in the high hardness site. Also, the boundary of hardness was clear. Results are summarized in Tables 1 to 3.
Using a nozzle in which orifices each having a solid circular cross-sectional shape with an outer diameter of 1 mm are staggered at a hole-to-hole pitch in the width direction of 6 mm and a hole-to-hole pitch in the thickness direction of 5.2 mm on an effective surface having a length in the width direction of 95 cm and a length in the thickness direction of 46.8 mm (10 lines), the obtained polyester-based thermoplastic elastomer (A-1) was ejected downward of the nozzle at a spinning temperature (melting temperature) of 240° C., at a single hole discharge amount of 1.31 g/min. Cooling water was located at 30 cm below the nozzle surface, and a pair of stainless endless take-off conveyer nets with an opening width of 30 mm interval was located parallel with each other in such a manner that the conveyer nets partially come out above the water surface. On the conveyer nets above the water surface, the molten ejected filament was meandered to form a loop, and a three-dimensional net structure was formed while the contact parts were fused. While both sides of the net structure in a molten state were sandwiched by the take-off conveyer nets, the net structure was drawn at a take-off speed of 1.15 m/min for the part that is to be a high hardness site and 3.00 m/min for the part that is to be a low hardness site, into cooling water and solidified to flatten both sides in the thickness direction. Thereafter, the net structure was cut into a predetermined size and subjected to a drying treatment with hot air at 110° C. for 35 minutes to obtain the net structure.
The obtained net structure was a net structure mainly composed of round hollow cross-sectional fibers having a fiber diameter of 0.45 mm and a circular cross-sectional shape. The average thickness of the net structure was 30.2 mm, the average thickness of the high hardness site was 30.1 mm, the average thickness of the low hardness site was 30.3 mm, the apparent density of the high hardness site was 0.064 g/cm3, the apparent density of the low hardness site was 0.025 g/cm3, the number of junction points in the high hardness site was 281 pieces/g, and the number of junction points in the low hardness site was 148 pieces/g. In the melting curve measured with a differential scanning calorimeter (DSC), the endothermic peak top temperature appearing at the melting point of the thermoplastic elastomer constituting the continuous filament or lower was 129.3° C. in the high hardness site and in the low hardness site.
Regarding the obtained net structure, the 25% compressive hardness of the high hardness site was 15.5 kg/φ200, the 25% compressive hardness of the low hardness site was 3.2 kg/φ200, and in the panelist evaluation, evaluation of texture in the high hardness site was ⊚ whereas in the low hardness site, poor texture was felt moderately, and the evaluation was × to Δ. Although the weight was within the normal design range, the weight was heavier due to the high apparent density in the high hardness site. Also, the boundary of hardness was clear. Results are summarized in Tables 1 to 3.
Using a nozzle in which orifices each being a triple-bridged hollow forming orifice for thick fiber having an outer diameter of 5 mm and an inner diameter of 4.4 mm are staggered at a hole-to-hole pitch in the width direction of 9 mm and a hole-to-hole pitch in the thickness direction of 7.8 mm on an effective surface having a length in the width direction of 95 cm and a length in the thickness direction of 54.6 mm (8 lines), the obtained polyester-based thermoplastic elastomer (A-1) was ejected downward of the nozzle at a spinning temperature (melting temperature) of 240° C., at a single hole discharge amount of 4.45 g/min for the part that is to be a high hardness site and at a single hole discharge amount of 2.65 g/min for the part that is to be a low hardness site. Cooling water was located at 36 cm below the nozzle surface, and a pair of stainless endless take-off conveyer nets with an opening width of 45 mm interval was located parallel with each other in such a manner that the conveyer nets partially come out above the water surface. On the conveyer nets above the water surface, the molten ejected filament was meandered to form a loop, and a three-dimensional net structure was formed while the contact parts were fused. While both sides of the net structure in a molten state were sandwiched by the take-off conveyer nets, the net structure was drawn at a take-off speed of 1.77 m/min, into cooling water and solidified to flatten both sides in the thickness direction. Thereafter, the net structure was cut into a predetermined size and subjected to a drying treatment with hot air at 110° C. for 35 minutes to obtain the net structure.
The obtained net structure was a net structure composed of hollow cross-sectional fibers with a round cross-sectional shape having a main fiber diameter of 0.99 mm in the high hardness site and hollow cross-sectional fibers with a round cross-sectional shape having a main fiber diameter of 0.84 mm in the low hardness site. The average thickness of the net structure was 44.3 mm, the average thickness of the high hardness site was 44.3 mm, the average thickness of the low hardness site was 44.3 mm, the apparent density of the high hardness site was 0.049 g/cm3, the apparent density of the low hardness site was 0.029 g/cm3, the number of junction points in the high hardness site was 120 pieces/g, and the number of junction points in the low hardness site was 154 pieces/g. In the melting curve measured with a differential scanning calorimeter (DSC), the endothermic peak top temperature appearing at the melting point of the thermoplastic elastomer constituting the continuous filament or lower was 129.2° C. in the high hardness site and in the low hardness site.
Regarding the obtained net structure, the 25% compressive hardness of the high hardness site was 16.6 kg/φ200, the 25% compressive hardness of the low hardness site was 8.1 kg/φ200, and in the panelist evaluation, evaluation of texture in the high hardness site was ⊚, whereas in the low hardness site, poor texture was felt moderately, and the evaluation was Δ. Also, the weight was within the normal design range, and the boundary of hardness was clear. Results are summarized in Tables 1 to 3.
This application claims priority to Japanese Patent Application No. 2022-060475, filed on Mar. 31, 2022. All of the contents of the Japanese Patent Application No. 2022-060475, filed on Mar. 31, 2022, are incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-060475 | Mar 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/012544 | 3/28/2023 | WO |
